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HETEROGENEOUS WIRELESS NETWORK
USING NON-ORTHOGONAL MULTIPLE ACCESS
METHOD IN 5G FOR
SECRET COMMUNICATION
A thesis submitted to Gujarat Technological University
for the Award of
Doctor of Philosophy
in
Electronics and Communication Engineering
by
Pankaj Manubhai Patel
[139997111012]
Under the supervision of
Dr Chetan B Bhatt
GUJARAT TECHNOLOGICAL UNIVERSITY
AHMEDABAD
SEPTEMBER - 2021
copyPankaj Manubhai Patel
DECLARATION
I declare that the thesis entitled lsquoHeterogeneous Wireless Network using Non-
Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo submitted
by me for the degree of Doctor of Philosophy is the record of research work carried out
by me during the period from January 2014 to November 2021 under the supervision
of Dr Chetan B Bhatt and this has not formed the basis for the award of any degree
diploma associateship fellowship titles in this or any other University or other
institution of higher learning
I further declare that the material obtained from other sources has been duly
acknowledged in the thesis I shall be solely responsible for any plagiarism or other
irregularities if noticed in the thesis
Signature of the Research Scholar Date 17092021
Name of Research Scholar Pankaj Manubhai Patel
Place Ahmedabad
CERTIFICATE
I certify that the work incorporated in the thesis lsquoHeterogeneous Wireless Network
using Non-Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo
was submitted by Shri Pankaj Manubhai Patel was carried out by the candidate under
my supervisionguidance To the best of my knowledge (i) the candidate has not
submitted the same research work to any other institution for any degreediploma
Associateship Fellowship or other similar titles (ii) the thesis submitted is a record of
original research work done by the Research Scholar during the period of study under
my supervision and (iii) the thesis represents independent research work on the part of
the Research Scholar
Signature of Supervisor Date 17092021
Name of Supervisor Dr Chetan B Bhatt
Place Ahmedabad
Coursework Completion Certificate
This is to certify that Mr Pankaj Manubhai Patel enrolment No 139997111012 is a
PhD scholar enrolled in the PhD program in the branch Electronics and
communication Engineering of Gujarat Technological University Ahmedabad
(Please tick the relevant option(s))
HeShe has been exempted from the coursework (successfully completed during
the MPhil Course)
HeShe has been exempted from Research Methodology Course only
(successfully completed during the MPhil Course)
HeShe has successfully completed the PhD coursework for the partial
requirement for the award of PhD Degree His Her performance in the
coursework is as follows
Grade Obtained in Research Methodology
(PH001)
Grade Obtained in Self Study Course
(Core Subject)
(PH002)
BC BB
Supervisorrsquos Sign
Name of supervisor Dr Chetan B Bhat
Originality Report Certificate
It is certified that PhD Thesis titled lsquoHeterogeneous Wireless Network using Non-
Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo by Shri
Pankaj Manubhai Patel has been examined by us We undertake the following
a The thesis has significant new workknowledge as compared to already
published or is under consideration to be published elsewhere No sentence
equation diagram table paragraph or section has been copied verbatim from
previous work unless it is placed under quotation marks and duly referenced
b The work presented is original and the own work of the author (ie There is no
plagiarism) No ideas processes results or words of others have been presented
as the Authors own work
c There is no fabrication of data or results which have been compiledanalyzed
d There is no falsification by manipulating research materials equipment or
processes or changing or omitting data or results such that the research is not
accurately represented in the research record
e The thesis has been checked using (copy of originality report attached) and found
within the limits as per GTU Plagiarism Policy and instructions issued from time
to time (ie Permitted similarity index lt=25)
Signature of the Research Scholar Date 17092021
Name of Research Scholar Pankaj Manubhai Patel
Place Ahmedabad
Signature of Supervisor Date 17092021
Name of Supervisor Dr Chetan B Bhatt
Place Ahmedabad
132
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SODH PAPER FOR PLAGRIASMdocxDocument SODH PAPER FOR PLAGRIASMdocx (D47816804)
1
PhD THESIS Non-Exclusive License to
GUJARAT TECHNOLOGICAL UNIVERSITY
In consideration of being a PhD Research Scholar at GTU and in the interests of the
facilitation of research at GTU and elsewhere I Pankaj Manubhai Patel has Enrollment
No139997111012 hereby grants a non-exclusive royalty-free and perpetual license to
GTU on the following terms
a) GTU is permitted to archive reproduce and distribute my thesis in whole or in part
andor my abstract in whole or in part (referred to collectively as the ldquoWorkrdquo) anywhere
in the world for non-commercial purposes in all forms of media
b) GTU is permitted to authorize sub-lease sub-contract or procure any of the acts
mentioned in paragraph (a)
c) GTU is authorized to submit the Work at any National International Library under
the authority of their ldquoThesis Non-Exclusive Licenserdquo
d) The Universal Copyright Notice (copy) shall appear on all copies made under the authority
of this license e) I undertake to submit my thesis through my University to any Library
and Archives Any abstract submitted with the thesis will be considered to form part of
the thesis
f) I represent that my thesis is my original work does not infringe any rights of others
including privacy rights and that I have the right to make the grant conferred by this
nonexclusive license
g) If third party copyrighted material was included in my thesis for which under the terms
of the Copyright Act written permission from the copyright owners is required I have
obtained such permission from the copyright owners to do the acts mentioned in paragraph
(a) above for the full term of copyright protection
h) I retain copyright ownership and moral rights in my thesis and may deal with the
copyright in my thesis in any way consistent with the rights granted by me to my
university in this non-exclusive license
i) I further promise to inform any person to whom I may hereafter assign or license my
copyright in my thesis of the rights granted by me to my university in this non-exclusive
license
j) I am aware of and agree to accept the conditions and regulations of a PhD including
all policy matters related to authorship and plagiarism
Signature of the Research Scholar
Name of Research Scholar Pankaj Manubhai Patel Date 17092021
Place Ahmedabad
Signature of Supervisor
Name of Supervisor Dr Chetan B Bhatt Date 17092021
Place Ahmedabad
Seal
i
ABSTRACT
The landscape of future fifth-generation (5G) radio access networks is
expected to seamlessly and ubiquitously connect everything and
support higher traffic volumes densely connected wireless devices and
diversified requirements on reliability latency battery lifetime etc as
opposed to the current fourth-generation (4G) cellular networks
Moreover in unexpected or emergencies (such as disaster relief and
service recovery) the deployment of terrestrial infrastructures is
economically infeasible and challenging due to high operational
expenditure as well as sophisticated and volatile environments To
address such novel issues intelligent heterogeneous architecture by
leveraging unmanned aerial vehicles (UAVs) (or commonly known as
drones) has been considered to be a promising new paradigm To
improve the system performance of UAV communication in 5G
networks physical layer techniques are of much concern as they affect
the applications of UAVs significantly In this research work security
aspects of NOMA-based UAV communication network have been
considered for optimization as physical layer security in a wireless
communication network is not as robust as wired communication due to
fading and varying SNR scenarios Here primarily two usersrsquo models
as the trusted and untrusted user communicating with BS have been
optimized for outage-optimal performance considering pair Outage
probability and Secrecy outage probability as performance metrics The
achieved results are extended to multi-user scenarios also and for the
optimal policymaking dynamic programming and Partially Observable
Markov Decision Process (POMDP) optimization approaches have
ii
been simulated and verified The simulated results have shown that
POMDP has potential consideration as a resource scheduling
optimization technique in the NOMA-UAV communication network for
providing secure and more robust performance
iii
Acknowledgment
Completing a PhD is a tough task that requires hard work and a lot of effort This is
often an overwhelming but also great experience that I would not have been able to
complete without the assistance and support of so many people Thus it is my great
pleasure to thank all those people First of all I would like to thank almighty for giving
me the strength to carry out this task I would like to deeply thank Dr Chetan B Bhatt
my supervisor for his guidance encouragement and support over these years This
research work would not have been possible without his constructive pieces of advice his
systematic guidance and his patient support thought out the duration of my research work
I would like to express my sincere gratitude to Dr Harshal A ALOORKAR and Dr
KIRAN R TRIVEDI Dr Mehul Raval my doctoral progress committee members Their
rigorous style of reviewing and constructive feedback with valuable suggestions of Dr
Prakash Gajjar Mr Hitesh Panchal and Mrs Monali Mandli who spent their valuable
time whenever required for discussing aspects of this work and provided relevant material
as well Mr Parth Modi and Mr Jagadish Patankar to initiate and inspired me a lot to
continue my work Mr Mukesh Sharma who help in maintain documents I am also
thankful to my parents and family members who always stood with me in each critical
situation and supported me endlessly I am thankful to all EC departments of various
polytechnic and degree engineer colleges for their cooperation in every possible means
Lastly I would thank all the people who directly or indirectly helped me during this very
important phase of my life
Pankaj Manubhai Patel
vi
List of Abbreviation
3GPP 3rd Generation Partnership Project
5G Fifth Generation
A2G Air to Ground
AWGN Additive White Gaussian Noise
BDM Bit Division Multiplexing
BS Base Station
BPCU Bits Per Channel Use
CDMA Code Division Multiple Access
CR Cognitive Radio
CSI Channel State Information
CNPC Control and Non-Payload Communications
CRN Cognitive Radio Networks
D2D Device-to-Device
DCP Difference of Concave Programing
DOMP Dynamic Optimization Method of Programming
FR Floating Relay
GSM Global System for Mobile Communications
HLPSL High-Level Protocol Specification Language
ICT Information and Communication Technology
IoT Internet of Things
IRS Intelligent Reflecting Surface
IMT Information Management Technology
vi
LDS Low-Density Spreading
LTE Long Term Evolution
LTE-A Long Term Evolution Advance
MCR Multicast Cognitive Radio
MI Mobile Internet
MIMO Massive Multiple-Input Multiple-Output
mm-Wave millimeter Wave
MTC Machine-Type Communication
MUSA Multi-User Mutual Access
NOMA Non-Orthogonal Multiple Access
OFDMA Orthogonal Frequency Division Multiple Access
OMA Orthogonal Multiple Access
OP Outage Probability
POMDP Partially Observable Markov Decision Process
PLS Physical Layer Security
PDMA Pattern Division Multiplexing Control
PUN Primary User Networks
QoS Quality of Service
RIS Reconfigurable Intelligent Surface
RNRF Random Near-Random Far
Rs Target Secrecy Rate
SAGIN Space-Air-Ground Integrated Networks
SIC Successive Interference Cancellation
STBC Space-Time Block Coding
vi
SBF Secrecy Beam Forming
SCMA Sparse Code Multiple Access
SOP Secrecy Outage Probability
TAS Transmit Antenna Selection
TDMA Time Division Multiple Access
UAVC Unmanned Aerial Vehicle Communication
UMTS Universal Mobile Telecommunication Systems
URLLC Ultra-Reliable Low Latency Communication
vii
List of Figures
Figure Title Page
No
11 Usage of wireless sensor network and UAV in the
hazardous disaster control
6
12 UAV network applications types with security services
architecture
8
13 UAV-assisted heterogeneous network architecture 12
14 Security problems in the UAV 15
15 Comparative analysis of NOMA vrsquos OMA 18
21 Vehicular communication NOMA system 28
22 RS-NOMA against an external eavesdropper 31
31 Downlink NOMA network 44
32 Uplink NOMA network 46
33 Multi-two user architecture of NOMA system 49
34 Flow Diagram of the proposed system 50
35 Near and Far User 51
41 Impact on Sop with increase distance between BS and user U2 60
42 Impact on Sop with increase distance between BS and user U2 61
43 Feasible pairing t Vs pair OP 61
44 Infeasible pairing t Vs pair OP 62
45 Secrecy outage probability 63
46 Pair outage probability 63
47 SNR versus Strictly positive secrecy rate 64
48 Power radiated by per MMBs antenna 64
viii
List of Tables
Table Title Page
No
11 Physical layer hazards and measures in UAV wireless
communication network
13
21 Comparative analysis 33
31 List of parameters59 54
41 Simulation parameters 59
ix
Table of Content
Sr
No
Title Page
No
I Abstract I
II Acknowledgment II
III List of Abbreviation III
IV List of Figures Iv
V List of tables V
1 Introduction 1
11 Modern technology and its needs 1
111 Long term evolution of 4G network 2
112 Migration from 4G LTE to 5G for UAV communication 3
12 UAV assisted communication in heterogenous sensor network 5
121 Introduction to UAV Communication network 7
122 Tyews of UAVs 8
1221 UAVs as flying BSs 8
1222 UAVs as aerial UBs 10
13 Unmanned aerial vehicle for 5G network 11
14 Physical layer insecurity in UAV communication network 12
141 Principles of security 13
15 Non-Orthogonal Multiple Access (NOMA) system secured
communication
16
151 Comparison of NOMA Vs OMA 16
1511 Spectral throughput and efficiency 17
1512 User fairness and higher lately 17
1513 Compatibility 17
16 Problem identification 18
17 Motivation 19
18 Aim and objective of the research 20
19 Thesis organization 21
2 Literature review 23
x
21 Integration of UAV Networks for 5G and B5G communication 23
22 UAV-NOMA in physical layer security enhancement 26
23 Research methodology 38
24 Summary 39
3 System model for NOMA-UAV communication 41
31 NOMA -UAV system secured communication for 5G 41
311 The basic scheme of NOMA 41
312 Downlink of NOMA 44
313 Uplink of NOMA 46
314 Comparison of NOMA and OMA 47
32 PLS performance metrics in NOMA -UAV communication 47
321 SOP and OP - two user and multi-user NOMA system 48
322 System Model 48
323 Partially Observable Markov Decision Process-POMDP 50
324 Problem formulation 52
33 Performance Analysis Improving PLS Insecurity of NOMA
System
53
331 The pair OP calculation 53
332 Pseudo-code for the proposed algorithm 55
34 Summary 57
4 Result and discussion 58
41 Performance measure of secured NOMA-UAV communication
model
58
42 Numerical result and discussion 59
421 Feasible amp Infeasible pairing of trusted amp untrusted
users
60
422 The secrecy outage probability and pair outage
probability
62
423 SNR versus strictly positive secrecy rate 63
424 Power radiated by per MMBs antenna
64
43 Conclusion and scope of future work 65
431 Conclusion 65
432 Future scope 66
xi
5 References 67
8
Publications 78
1
CHAPTER -1
INTRODUCTION
11 Modern technology and its needs
Mobile technology has undergone various generational shifts transforming the
cellular framework into a worldwide set of interconnected networks In recent days
the fifth generation (5G) has delivered voice as well as video streaming It has a
very complex range of networking services for more than nine billion users and also
billions of devices that will be connected (Hu 2016) However 5G offers a new
outlet for reflection It involves a radial network architecture for the installation of
communication-type machines 5G network can also include powerful support
applications with widely varying operating parameters 5G is a blend of network
technologies that have been developed The new 5G technology will be able to
exchange information anywhere every time for the benefit of people enterprise
and society and technical environments using a restricted access bandwidth to
carry data Now it is more than a modern series of technologies and as opposed to
previous generations would entail tremendous infrastructure or machinery
upgrades This technology aims to expand on the advances that telecommunications
systems have already achieved The projected standards of efficiency that
technologies would need to resolve are
bull Five times reduce end-end latency
bull Ten to a hundred times the higher complex rate of user data
bull Battery life is ten times longer
bull 10 to 100 times higher number of connected devices
In this research work the UAV-assisted communication over the 5G network has
been proposed with enhanced physical layer security aspects NOMA has been
proposed as the reference framework architecture for UAV communication as one
of the recent popular 5G techniques Along with the advantage of suitability in UAV
communication network NOMA has the disadvantage of insecurity in the physical
layer Here the migration of Long Term Evolution (LTE) to advanced physical layer
2
security for Unmanned Aerial Vehicle communication (UAV) over 5G network has
been proposed and also improve the insecurity of Non-Orthogonal Multiple Access
(NOMA) System We will discuss in the further chapter the proposed work This
chapter describes the introduction and basic concepts of the 5G networks with
methodology techniques and types It states the problem identification motivation
and further aim and objective of this work
111 Long Term Evolution of 4G Network
LTE is customary for 4G wireless broadband trends that provide improved network
capability and gives mobile device users speed It offers high peak data transform
rates in the range of 100 Mbps and 30 Mbps downstream and upstream
respectively It provides a capacity of scalable bandwidth mitigated latency and
backward compatibility with the previous Global System for Mobile
Communications (GSM) and Universal Mobile Telecommunication Systems
(UMTS) technology
The fourth development of cellular networks (4G) has already been developed to
meet the standards of the 3G and 2G families Every 10th year a new mobile
generation claimed to be familiarized with the first 1G system in 1981 tracked by
the 2G system that went on to roll out in 1992 and 3G launched in 2001 growth in
the year 2002 of 4G networks The actual new revolution began in December 1998
with the 3rd Generation Partnership Project (3GPP) With high-quality video and
images 3G networks are designed for multimedia networking with them Peoples
communication can also be enhanced and connectivity to public and private
network information and resources has improved with higher frequencies and new
flexible communication features third-party device applications
With the start of LTE-Advanced several vital demands and improvements are
beginning to emerge Various importance purposed for LTE-Advanced can be
exemplified as follows (Abed)
bull Provides spectrum output with LTE delivered more than three times
bull Spectrum can help scalable bandwidth and convergence of the spectrum
where it is necessary to use a non-contiguous range
3
bull Provides uplink and downlink spectrum output that varies between
15bpsHz and 30bpsHz
bull The edge throughput must be twice that of the user cell in LTE
bull From idle status to connected status the communication latency scenario is
smaller than 50msec and less than 5msec for direct packet transfer
bull Any users total throughput must be three times that of LTE
bull LTE advancement will provide 3GPP as well as LTE compatibility via inter
networking
bull The mobility conditions that are used in LTE are identical
The latest LTE advanced requirements are not yet included in device
specifications there are high-level purposes Before it is fixed in the specifications
and needs to be tested much effort remains to be approved
112 Migration from 4G LTE to 5G for UAV communication
The productive implementation of a UAV communication network in 4G and the
upcoming wireless network is included in identifying combined solutions to test
the correlation with both multitudes and also energy-efficient transmission Then
the process of the UAV-BS to optimize coverage and power It is stated that the
energy efficiency of the UAV-aided communication system is needed Efficient
energy utilization contributes to increased air time in the contact system and
increased joulesbits at a provided energy level Also aerial cell coverage and
ability may be because of various parameters such as antenna gains transmission
strength radio access technology UAV altitude and deployment environment
4G is the fourth generation of network infrastructure technologies to replace 3G and
in addition to the popular 3G4G methods Code Division Multiple Access
(CDMA) Time Division Multiple Access (TDMA) and Orthogonal Frequency
Division Multiple Access (OFDMA) Researchers are designing the latest Non-
Orthogonal Multiple Access (NOMA) technologies to be used because of their
capability to improve the performance of communication networks Non-
4
orthogonality-based device designs have recently been developed for use in
communication networks and drawn considerable interest from researchers
Henceforth Multiple Access (MA) methods can be sub-divided as OMA and
NOMA Each user may utilize orthogonal communication resources to determine
multiple access interference inside a frequency band code and time slot in OMA
Its methods such as First generation (1G)- FDMA 2G -TDMA 3G -CDMA and
4G - OFDMA have been used in previous network generations In NOMA by
producing a higher spectral efficiency however enabling some amount of multiple
entree intrusion in receivers and multiple users may use non-orthogonal resources
simultaneously Recently the credibility of NOMA as a solution to the problems of
the next generation of wireless networks has been increased Compared with OMA
technologies NOMA has been described to improve spectral quality be well-
adjusted with air connectivity and can provide accommodations for multiple
strategies at the same time of frequency Therefore enabling excellent progress to
massively correlated devices
In particular NOMA also affects mitigating interference by using OFDMA as an
orthogonal method or through offering a standard intra-cluster access beam across
multiple users and inter-cluster access in NOMA Recent studies have concentrated
primarily on the provision of Air to Ground (A2G) connectivity services through
optimization of a different point of view
The output of the UAV-based communication network was discussed in the Device
to Device (D2D) implementation setup The proposed system hypothesized
interference caused through D2D network nodes deprived of acknowledging the
occurrence of global BS Also several studies addressed the efficiency of NOMA
It permitted the deployment of fixed-wing to assist coverage in-ground user located
outer location of offloaded BS
NOMA systems are divided into two categories namely code domain and power
domain multiplexing In the power domain user accounts are allocated to different
power coefficients as per their channel complaint to reach optimal device
efficiency Multiple user signals are applied to the side of the sender Then on the
received signal Successive Interference Cancellation (SIC) is implemented to
decipher signals in sequential order until the predicted signal is achieved offering
5
a good trade-off between efficiency of the system and user fairness Different code
domain multiplexing is Sparse Code Multiple Access (SCMA) Low-Density
Spreading (LDS) and Multi-User Mutual Access (MUSA) Compared to power and
code domain multiplexing there are alternate NOMA techniques such as Bit
Division Multiplexing (BDM) and Pattern Division Multiplexing Control (PDMA)
However this multiplexing is capable of improving the efficacy of spectral It
requires a large transfer of bandwidth which is not appropriate for new methods
But on the other side the power domain has direct execution since there is no need
for significant improvements to the current networks It also does not necessitate
bandwidth to increase spectral efficiency In this chapter the main emphasis
depends on the power domain NOMA While OMA strategies can produce the best
results also with necessary receivers due to no mutual intervention among users in
an optimal situation they cannot even resolve increasing problems due to growing
demands on connectivity growth and even beyond
12 UAV assisted communication in heterogeneous sensor network
Wireless communications had created a golden chance for urban and rural
territories The LTE (Long term evolution) and LTE-A (Long term evolution
Advance) had offered the service (with QoS) for all customers through wireless
The traffic properties in the machine type communications (MTC) and the
accumulation of the MI (Mobile Internet) had made the difficulty of implementing
the cellular communication networks Installing base stations was impractical in the
urban areas due to its cost To overcome this issue the UAV suggested that it
contains the merits of compatibility and high battery life and is affordable Most of
the devices like the sensor nodes and professional cameras had been used in UAV-
assisted networks Here the UAV-assisted floating relay (FR) was launched in the
cellular communication networks UAVs were implemented more with WSN
(wireless sensor networks) The base stations were adopted with the UAV So the
MI and MTC traffic challenges were controlled (Yue Li amp Cai 2017)
UAV-assisted Heterogeneous networks had implemented in vast practical
applications UAV helped heterogeneous networks were applied in the military
department In the military the UAV had examined and surveyed the opposing
6
countryrsquos activities for security The UAV-based heterogeneous networks were
used in the military sectors where a novel authentication scheme was introduced
As The one-to-one communication via WSN was considered as secured
communication WSN had the disadvantage of consuming power The
authentication was implemented in the tool of Automated Validation
of Internet Security Protocols and Applications (AVISPA) in which the expression
had been written in the High-Level Protocol Specification Language (HLPSL)
programming language The authentication had evaluated between the user and the
base station Similarly the authentication between the user and the UAV was
calibrated The citizen and economic safety are predicted and conserved through
reliable communication in the military by obtaining foes exploration information
The faithful secured communication was confirmed using AVISPA (Rashid et al
2019)
Figure 11 Usage of wireless sensor network and UAV in the hazardous
disaster control
The integration of the wireless sensor networks and the unmanned aerial vehicle
UAV was analyzed and applied to manage the natural disaster illustrated in Figure
11 The aircraft can prevent the fire spreading drop sensors the temperature map
and biodiversity map by sensors the wildfire can easily route The wild animals can
7
be tracked and the dynamic data of moving animals can be gathered by WSNs The
biologists can fix the sensor in the animals collar the radiation that positively
affects humans can be observed in affected areas The WSNs help to prevent heart
attack of a person by monitoring heart rate The state of health can be known
through a message alarm using a GPRS system
The cooperative networks of WSN and UAV were implemented in the military
sector for the advantageous feature The UAV was providing good connections
overlapping and overall data rate The conventional UAV method aided sensor
networks concentrated only on the single tasks of monitoring accumulating
information and localization The multi-UAV had not been implemented in the
sensor networks The animal colony perception technique was utilized for
scheduling the resourced and the target assignment Functions of multi-data were
used for localization by the target recognition method (Gu Su et al 2018)
The Physical Layer Security (PLS) was achieved through 5G technologies delicate
coding for the PLS dense MIMO multi-input multi-output mm-Wave frequency
band using heterogeneous sensor networks NOMA and full-duplex mode of
communication IoT and Machine-type communications (MTC) emerged in the 5G
systems (Wu et al 2018)
121 Introduction to UAV communication network
The usage of the UAV will develop more in the next era These pre-programmed
aircraft are intended for applications in several civil settings as well as industrial
visualization agriculture rescue and search and then receiving of scientific data
These devices are called the unsuccessful inaccuracy of drones which must be
incorporated into the system of national airspace as well as worldwide The usage
of UAVs in the neutral form is always secure It has a direct inference for the control
and a payload communication system that is utilized to function effectively
Similarly surveillance and navigation operations must be made more accurate and
consistent Due to these critical factors many kinds of research in a UAV testing
development and standardization difficulties are undergone through industries
education and governments
8
Even though civil aircraft had been operating for many years yet UAV offers new
consequences in terms of various flight profiles For example high dynamic
maneuvers and low elevation flights need bandwidth video and different ground
site characteristics namely clutter locations and elevation antennas which are low
This chapter explains the core topic of the proposed work The migration of LTE
4G towards the advanced one of the physical layers for UAV communication It has
higher mobility and lower expense identified in a broad range of applications
122 Types of UAVs
The UAVs have a two-network application with security services such as UAVs as
Flying Base Stations (BSs) and UAVs as Aerial BSs in the presence of
eavesdroppers
(a) UAVs as Flying BSs (b) UAVs as Aerial mobile UEs
Figure 12 UAV network applications types with security services
architecture
1221 UAVs as flying BSs
The required infrastructure can be destroyed in natural disasters particularly
tsunamis earthquakes and snowstorms and the requisite emergency data traffic
cause both overloading and congestion of neighboring mm-Wave (Zeng et al
2016) A capable explanation is to rapidly introduce low-altitude UAVs as flying
9
BSs in such a network breakdown to improve the communication infrastructure to
mitigate cell congestion or site failure thus creating a small aerial cell
In this situation wireless communications can occur in an ad-hoc manner with
UAVs to UEs UAVs to UAVs As highlighted in Figure-12 (a) and control
stations of UAVs to ground It will increase capability dramatically and enlarge the
target of wireless networks in provisional measures as it is possible to create LoS
communication links among UAVs and UEs supported on the ground Yet form an
operating aerial cell system to monitor ground segments of UEs mobility which is
more stable to minimize sporadic connectivity on the other side
Also this can be expanded to allow several UAVs-BSs to be deployed to increase
the exposure area for supporting a wide range of UEs A network period various
UAVs-BSs is entirely independent A new paradigm was introduced through
collaboration between UAVs-BSs to extend the feasibility for a single UAV from
either a stand-alone active sensor to a wireless network over the next generation
There is a growing concern about the privacy problem in tandem with the brief
introduction of this network Wireless protection is the central issue of the
communication level wherever eavesdropping subsidizes for deliberately listening
to a source of secret information which harms the extensive placement of UAV-
BSs
A UAV-BSs is to mount several antennas in the UAV-BSs the benefits of multi-
antenna innovations geographical degree of freedom that offers an ability for UAV-
BSs to transmit eavesdropping airborne beams
Notice that in UAV systems multi-antenna technology can be technically applied
while directly modifying the separation of the antennas The existing system has
shown that transmitted beam forming models can significantly boost the
confidentiality efficiency of wiretap channels for multiple antenna transmitters
Noise may be inserted with the signal to substantially degrade the acknowledged
SINR at the eavesdroppers to prevent the information overflow
10
1222 UAVs as aerial UEs
This has already been demonstrated by reaping the benefits of Wi-Fi and LTE
technologies through field trials (Van der Bergh et al 2016) UAV-UEs typically
get their tasks for a variety of convincing IoT applications mainly in air freight
services like the google wing project Unlike conventional land base package
delivery but UAV delivery has distinctive merits such as
bull Acceleration of land transport as UAVs are not liable to road jams
bull Connection to areas that are difficult to reach
bull Decreasing the use of capital about workforce and electricity
UAV distribution is significantly dependent on having reliable and secure wireless
communication among UAVs and ground BSs especially if the UAV needs control
outside LoS the UAV-UEs are used which can develop LoS connectivity to cellular
BSs The UAV-UEs on the one hand provides high-speed access to data as it can
fly continuously in either direction On the other hand the installation of UAV-UEs
can lead to significant interference with the ground BSs in the execution of their
missions
A wide-scale installation of UAV-UEs is only feasible for this reason if the issues
of interference management are tackled It is widely known that interference
negatively affects wireless networks As highlighted in Figure-12 (b) indeed aerial
and ground UEs are served through a cellular network with a possible eavesdropper
that tries to intercept the message intended for permissible basic UEs
A cost-effective approach is to be used for coordination among ground BS and
UAVs to enhance secure transmission which is part of the UAVs acting as friendly
transmitters to degrade the wiretapping channels efficiency and thus enhance
secrecy efficiency A UAV acting as a mobile jammer can dramatically and
dynamically change its position as near as possible to the earth eavesdropper and
distribute them by sending the radio signals whereas strong LOS connection
characteristics are a beneficial feature with less earthly fading and shadowing
impairment
11
13 Unmanned Aerial Vehicle for 5G Networks
UAVs have technologically advanced as a revolutionary movement in delivering
pervasive connectivity from either the platforms of the sky as aerial
communication particularly for temporary User Equipment (UEs) (B Li et al
2019) Due to fully controllable UAV flexibility through miniaturization as well as
continuous cost reduction low-altitude UAVs are rapid and flexible designed for
operation and reconfiguration They are probable to have higher Line-of-Sight
(LoS) ties to ground UEs
A broad range of applications like inspection of infrastructure precision farming
and disaster area monitoring is becoming accessible in this aspect Moreover
further projects have also been set up to employ aerial platforms for broadband
access to distant elements such as the Google Loon and the Facebook Drone Project
to mention Highly populated UEs are desperate for broadband wireless
communications with the coming 5G period and network providers are supposed
to maintain numerous networks with high demands for wireless data like
multimedia streaming and also video downloads The relentless growth in the
amount of traffic of mobile networks puts a burden on operators in the form of
higher capital and operational expenditure Deploying small cell networks is an
intuitive alternative to outsource cellular traffic
Although in unforeseen or temporary events as mobile environments are
complicated volatile and heterogeneous the implementation of terrestrial
infrastructures is difficult The accessibility of aerial access points to enable
extensive complex connections is one possible solution However in unforeseen or
temporary events as mobile environments are complicated volatile and
heterogeneous the implementation of terrestrial infrastructures is difficult The
accessibility of aerial access points to enable extensive complex connections is one
possible solution UAV communication performance benefits from the simplicity
of the compact transceiver and progressive control methods that obtain broad
exposure and set up internet networks
12
Figure 13 UAV-assisted heterogeneous network architecture
The above Figure 13 is depicted to build flexibility of the network with enhanced
ability and elasticity It is a good network that offers security endowment This is
due to the transmitting information to UAV communication which is tapped
through ground unauthorized user and is known as an eavesdropper
Here through eavesdropper based on the upper layer cryptographic techniques
wireless communication in contradiction of unauthorized access has been protected
However it is very tough to achieve because of key management as well as more
computational difficulties in developing network architecture PLS affects the
characteristics of intrinsic wireless networks as a fascinating preparation such as
interference noise fading loss collecting signal characteristics in malicious
eavesdroppers and techniques of signal processing
14 Physical Layer Insecurity in UAV communication network
Jamming is either a well-defined WSN attack on a physical layer It disrupts the
radio waves being used by nodes of the network The attacker successively
expresses the denial of the simple MAC protocol over the wireless network The
impressive network can be disrupted at which a single frequency is being used
13
throughout a network (Modares et al 2011) In addition jamming can increase
energy consumption in the node by inserting impudent packets The receiver nodes
will also generate resources when receiving the packets In (Jeon 2006) four
different terms of jamming attacks that an intruder could use to interrupt the
wireless network activity Tampering is yet another physical layer assault
Table 11 Physical layer hazards and measures in UAV wireless
communication network
(Kumar et al 2014)
Hazard Security measures
Jamming Channel blacklisting and hopping
Interference Channel hopping and blacklisting
Tampering Security and key modification
Sybil Physical security of the system
Table 11 describes physical layer hazards and their security measures in WSN
which tampering and jamming are considered as the main attack in the physical
layer in WSN
141 Principles of security
The security requirement of UAV communication network is as follows (Kumar et
al 2014)
Confidentiality Ensure that only the approved sensor nodes could get the contents
of the texts
bull Authentication Ensure that the data is introduced from the sound source
bull Integrity Ensure that every received text has not been modified to be sent
by unauthorized users
14
bull Freshness Make confirm that no old information has been reiterated
bull Availability services are feasible at any time through WSN or by a single
node
The standard attacks of the physical layer are as follows (Sastry et al
2013)
bull Jamming The transmission of the radio signal can interfere only with radio
frequencies used through WSN which is known as jamming As the
capacity grows it may influence more significant portions of the network
by transmitting other radio signals The opponent will use a few nodes to
occupy the entire channel This state is called physical layer jamming which
results in a denial of service In this scenario the opponent will not be
permitted to have any knowledge but will be capable of preventing
communication to any nodes
bull Tampering Often the nodes tampered through an opponent This mode is
called tempering Here the attackers can destroy exchange and
electronically confront nodes to obtain information from counter measures
towards jamming that have been planned as spread as well as frequency
hopping
bull A security mechanism is used in WSN to track avoid and recover from
security attacks A wide range of security schemes can be devised to counter
malicious threats which can be classified as high and low levels
bull Secrecy and Authentication Most network sensor applications need
protection from eavesdropping packet alteration and injection Early
networks are used for connection layer cryptography as this approach offers
the easiest deployment of network cryptographic solutions
bull Privacy Like all other conventional networks the radio networks have also
brought secret issues to allow Initially sensor networks are implemented
for legitimate purposes and can eventually be used unexpectedly
Knowledge of active sensor nodes as well as the acquisition of data is
exceptionally crucial
15
bull Critical launch and trust setup The primary prerequisite for setting up a
network is the development of keys (cryptography) Sensor devices
typically have minimal computing capacity and public cryptographic
primitives are too difficult to adopt Critical establishment and strategies
need to be scaled to network with thousands of nodes
bull Secure routing Routing as well as data forwarding is a problem that
confronts to facilitate communication in networks Regrettably the latest
protocols encounter a variety of security flaws
bull Robustness of communication Does An opponent challenges to interrupt
the operation of the network
Figure 14 Security problems in the UAV
Figure 14 illustrated the security difficulties in a UAV The physical layer security
in the UAV wireless networks was examined The UAV had affected by both active
eavesdropper and passive eavesdropper This paper proposed the trajectory design
and cooperative UAV for constraining the eavesdropper NOMA MIMO mm-
Wave frequency band in UAV would cause better spectral efficiency and security
(Xiaofang Sun et al 2019)
UAV implementation of the 5G communication was considered advantageous The
UAV was assumed as the novel wireless network technique for the territory users
and their base stations The UAV had resulted in high altitude So the UAV had
16
considered a superior line of sight At the same time the possibility of security
problems was raised in a UAV The secrecy in the existence of eavesdropper the
jammer in the ground was performed using the UAV UAV aided territory security
was proposed The UAV was involved in inspecting the eavesdropper and hazard
jammers on the base stations territory UAV had targeted the global position system
spoofing for assisting the authentic users and performed the role of an artificial
eavesdropper for excluding the eavesdropper and jammers in the ground (H-M
Wang et al 2019)
15 Non-Orthogonal Multiple Access (NOMA) System Secured
Communication
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
151 Comparison of NOMA Vs OMA
Comparison of the NOMA and OMA can be discussed as follows
17
1511 Spectral throughput and efficiency
In OMA a resource is allotted to the distinct user whether it is good or bad in a
channel scenario like OFDMA Thus the whole process moves from less
throughput and performance
While the same frequency is allotted to the multiple-use at the same time with good
or bad channel operation in NOMA here the weak user gets the allocated for the
resources which the strong user can also use it And the interference can be reduced
by the SIC process on the receptor side of the user Consequently the probability
with the increased spectral efficiency as well the high throughput will be
maximized
1512 User fairness and higher lately
A user of fair channel complaints has higher precedence to be served in OMA In
contrast a user with a poor channel complaint is to remain activity which causes
the issue of user fairness and higher latency Yet OMA cannot assist colossal
connectivity Whereas NOMA helps multiple users with various channel
procedures and offers increased fairness massive connectivity and lower latency
1513 Compatibility
NOMA has compatibility with the current and upcoming scenario meanwhile no
need for necessary changes to the previous methods As an instance NOMA has
been bought up in the 3G Partnership Project LTE Advanced (3GPP LTE) Though
NOMA contains many characteristics that can assist the upcoming generations and
it has some restrictions that can be explored with its full benefits Those restrictions
are as follows
bull Each user has to decrypt the signals of other users until decrypted their
signal the complexity of the receiver would be strengthened in NOMA as
opposed to OMA which creates a long pause
bull Also data on channel quality for all users should be returned to the BS but
this results in substantial CSI input overhead Furthermore if any issues
arise to any consumer during the SIC process the likelihood of consecutive
decrypting errors will be improved
18
Figure 15 Comparative analysis of NOMA vrsquos OMA
As an outcome the number of users is reduced to ignore the spread of such
debugging Another aim of restricting the number of users is that there must be
substantial variations in channel revenues between users with different channel
grievances to provide network reliability
16 Problem Identification
The NOMA-based architectures main feature is to configure trusted and untrusted
users when more than one eavesdropper is present in the dense setting of todayrsquos
and future sophisticated wireless communication networks This research aims to
examine the security efficiency suggested for mission-critical applications in the
NOMA-based UAV communication network The proposed system underpins two
user NOMA frameworks The possibility of paring both users was explored with
PHY performance measures in mind Outage probability (OP) and Secrecy Outage
Probability (SOP) Dynamic Optimization Method Programming (DP) and Partially
Observable Markov Decision Process (POMDP) optimization have also been
analyzed to explore the feasibility of achieving an outage-optimal output for the
pair under the heavy users secrecy outage restriction The optimized theoretical
findings are applied to the multiuser scenario The identifications were tested
through a computer model in which POMDP has shown substantial progress over
the dynamic optimization method to program
19
17 Motivation
Unmanned aerial vehicle (UAV) wireless communications have experienced an
upsurge of interest in both military and civilian applications due to its high
mobility low cost on-demand deployment and inherent line-of-sight air-to-ground
channels However these benefits also make UAV wireless communication
systems vulnerable to malicious eavesdropping attacks
Despite the promising gains brought by UAVs the open nature of air-to-ground
wireless channels makes secure information transfer a challenging issue
specifically on the one hand information signals transmitted over wireless LoS
channels are likely to be intercepted by some undesired receivers which lead to a
risk of information leakage On the other hand wireless UAV transceivers are
vulnerable to malicious jamming attacks Hence security plays an extremely
important role in UAV wireless communications Unfortunately traditional
encryption techniques require high computational complexity leading to a large
amount of energy consumption which may not be suitable for UAV systems As an
alternative physical layer security is computationally efficient and effective in
safeguarding wireless communication networks via exploiting the inherent
randomness of wireless channels As a result various physical layer techniques
have been proposed in the literature for guaranteeing communication security
NOMA is viewed as a promising technique to provide superior spectral efficiency
by multiplexing information signals at different power levels [13] Hence it is
expected that NOMA can bring additional rate and robustness to enhance the
achievable rate in UAV physical layer security communications Consider a
scenario where a UAV acts as a relay to facilitate data delivery to two receivers
with different security clearance levels within a maximum cruising duration T The
receiver with a lower security clearance level and a higher potential with an
eavesdropper Since it has a strong motivation in intercepting signals intended for
a receiver with a higher security clearance Then when the eavesdropper suffers
from a bad channel condition NOMA is adopted to forward both confidential and
public information simultaneously Otherwise UAV only broadcasts the public
information for security issues The mode selection between NOMA and unicast is
20
chosen based on the results of the proposed resource allocation optimization In
particular for maximizing the spectral efficiency one needs to jointly optimize the
transmission scheme resource allocation and UAVrsquos trajectory However the
coupled optimization variables generally result in non-convex optimization
problems which are difficult to solve optimally As an alternative an iterative
suboptimal algorithm based on successive convex approximation can be employed
to facilitate a computationally efficient joint design We have discussed that the
NOMA scheme always outperforms OMA in all the considered scenarios which
demonstrates the spectral efficiency advantage brought by NOMA in striking a
balance between public data rate and confidential data rate
The main motive of this research is to enhance the inherently insecure PHY layer
of the NOMA-based UAV communication network NOMA-UAV communication
network requires feasible paring between trusted amp untrusted users (attacker) for
cooperative communication mainly in real-time field applications The power
allocation factor need to be optimized as per the trustworthiness of the associated
users (reliable user) and keeping the outage probability minimum for secured and
cooperative communications The pair Outage Probability and the SOP have been
optimized jointly for feasible pairing between BS amp the associated Users
18 Aim and Objective of the Research
The proposed works main objective is to examine the design of a NOMA-based
UAV communication network for enhanced Physical Layer security (PLS)
features Remarkably it is anticipated infrastructures and resources to connect
numerous devices and provide various services Researchers these days
concentrating on ways to design a heterogeneous framework like deployed small
cells air and ground-based deploy multifarious communication methods in 5G
such as millimeter-wave (mm-Wave) device-to-device (D2D) massive multiple-
input multiple-output (MIMO) Cognitive Radio (CR) and so on for improving
spectrum and energy efficiency
As a critical need especially for emergency applications the adoption of NOMA
transmission of UAV communication needs to be improved PLS A new optimal
resource allocation algorithm for some more robust and stable communication in
21
single and multiuser scenarios has been suggested here The PLS in dense
heterogeneous sensor networks has improved by the feasible pairing of trusted and
untrusted users (K Cao 2019 T Zhao 2018) In the instance of untrusted users
dynamic programming and POMDP are subjected to the channel conditions
details optimizing OP and SOP as a restricted parameter accompanied by resource
allocation (Davis 2018 L Hou 2018)
The main aim of the proposed research work areas
bull To analyze the underlying NOMA UAV communication framework with
enhanced Physical Layer security (PLS) implications for particular quest
applications
bull To examine the potential pairing of trusted and untrusted users in the
NOMA-based UAV contact network with two users and multiuser scenarios
for certain channel conditions called Channel State Information (CSI)
bull To maximize resource allocation among trusted and untrusted users by
pairing OP and Secret Outage Probability (SOP) as performance measures
with the POMDP optimization method
bull To evaluate POMDP and dynamic programming resource allocation with
two users and multiple users for both protected NOMA-based UAV
communication network scenarios
19 Thesis Organization
Chapter 1 Provides the introduction and basic concept of the proposed work with
the problem identification motivation and aim and objective of the proposed work
Here we described LTE 4G and its advanced techniques than about the NOMA and
its basic scheme UAV concepts represent their types and basic working strategy
Chapter 2 Provides a survey of the existing technologies which is related to the
proposed work The NOMA transmission schemes Merits and De-merits related
to security UAV assisted communication in heterogeneous sensor networks UAV
networks of 5G and beyond communications has been explained then about UAV-
NOMA PHY secured communication techniques as well
22
Chapter 3 Describes the proposed work of improvement of physical layer
insecurity of the NOMA The overflow and its performance measures with
simulated output have been defined in this chapter
Chapter 4 Describes Migrations proposed work from 4G LTE to advanced PHY
techniques for UAV communication The overflow and its performance measures
with simulated output have been explained in this chapter Concludes and explains
the proposed work with its outcome and the future scope of the proposed work
23
CHAPTER 2
LITERATURE REVIEW
21 Integration of UAV Networks for 5G and B5G communication
5G and B5G had been anticipated to give a unique connection among universal
users The UAV had been emerged for its advantage of wireless network and
relaying high data rate The UAV in the 5G and B5G was introduced and 5G and
B5G were updated with the new concept of Space-Air-Ground Integrated Networks
(SAGIN) Three layers were established named physical network communication
link and evaluation Besides the usage among the dense population IoT was
applied in satellite communication In which the IoT had provided the uninterrupted
service with high data rate communication The scope for flying UAVs had been
created for enhancing the number of mobile users with IoT (Ali et al 2018)
5G and B5G had projected the UAV as the vital constituent One to multiple point
transmission can be possibly advance in 5G and B5G The structural design of the
upcoming UAV (multi-tier drones) was driven by the routine of different structures
like the maximum functioning altitude communication overlap coverage and
determination The UAVs practicability (multi-tier drones) among conventional
UAVs (single-tier drones) is scrutinized in that perspective By ascertaining the
circumstances UAV (multi-tier drones) could supplement the older terrestrial
networks with RF Initially UAV (multi-tier drones) and drone-aided wireless
networks were related to finding the tasks The modified UAV (multi-tier drones)
and the drone-administered wireless networks were analyzed The enactments of
UAV (multi-tier drones) were scrutinized in the contest of spectral efficiency in the
downlink networks Their effect had exhibited the detailed network parameters The
UAV distribution (multi-tier drones) was considered advantageous for the spectral
efficiency from the downlink transmission over traditional terrestrial wireless
networks (Sekander et al 2018)
The growth of 5G and B5G wireless networks prominently hang on the
incorporation of the terrestrial and aerial systems in innovative heterogeneous
network architecture They had advanced a creative and tangible multiple UAV
24
made up of cluster UAV ndash base stations and Poisson point process with UAV and
mm-Wave frequency band Ground user equipment and UAV had exhibited as the
Poisson cluster process and then spread around the public cluster in the distinctive
cluster In particular the scrutiny was accompanied by the accumulation of extra
tiers Extra tiers were made up of multi-cluster UAV base stations and single ground
user base stations in the characteristic cluster Four-tier network systems were
designed correspondingly from the subdivision of the above-said base stations
Two-tier and four-tier association patterns were built for discovering the
involvement of the cluster networks The coverage probability for the downlink and
network throughput was derived (Ji et al 2020) The numerous subordinate title
role of the multifaceted communication systems was performed by the UAVs The
UAV was acted as the air relay in the maintenance of ground networks The UAVs
were used in the countryside hilly zones whereas the communication was
inadequate The author anticipated resolving the viable communication difficulty in
5G and B5G vehicular ad-hoc The associate communication pattern established on
the smart UAVs was planned given the crisis condition of the car ad-hoc The smart
UAVs were supporting the vehicular ad-hoc strong communication in real
situations Above and beyond its actual characteristics of the vehicular ad-hoc were
needed to be endangered to avoid the prohibited features from attaining and
exhausting for law-breaking practices Innovative UAV with a secret authentication
key arrangement was recommended in the 5G and B5G vehicular ad-hoc Because
of supporting efficiency the vehicle network which guaranteed communication
confidentiality was not negotiated The suggested pattern was confirmed to be
unaffected by numerous outbreaks by exploiting the broadly applied natural or
random ROR scheme
Furthermore the projected scheme had well calibrated the communication
overhead from the performance estimation (J Zhang et al 2020) The UANs had
obtained a phenomenal role in the research area the emergent sector of aerial
robotics The parcel transport organization monitoring occurrence shooting
surveillance and tracing were the metropolises general operations utilizing the
UAV Various domains would use 5G and B5G to improve UAV networks UAV
ecological unit was advantageous in present 5G and B5G mobile communications
For UAVs intrinsic features they were concerned for flexible movement of three-
25
dimensional space independent actions and smart locations These devices were
provided with extensive scope in cellular networks The author proposed an in-
depth assessment of implementing cooperation between UAV and 5G and B5G In
which UAV had been assimilated as a novel user equipment of aerial in present
mobile communications The UAV had implemented the duty of flying users within
the network coverage named the cellular-connected UAVs in this amalgamation
The author showed a broad examination of the incorporation tasks with 5G and
B5G novelties Continued efforts in the prototyping and validation of mobile
communication UAVs were conducted using the ground trial The paper had
focused on the current growth in 3GPP The social-economic had not been taken
into account which was considered disadvantageous (Mishra amp Natalizio 2020)
The UAV was anticipated as the significant constituent in the 5G and B5G wireless
networks 5G enables the UAV to be used in broadcasting and end-to-end
communications using the small UAV They needed a devoted and endangered
aerial spectrum in the aircraft cargo by letting small UAVs run in space in
supervisory authority The security information was obtained from the link Control
and Non-Payload Communications (CNPC) The security information contained
the regulation of UAV and the line of sight of terrestrial The CNPC application in
the 5G and satellite communication was scrutinized in this paper Payload
communication like mm-Wave networks and UAV were analyzed in this paper The
direction-finding and reconnaissance difficulties were examined UAV
communication systems were scrutinized and the hardware challenges were
discussed (Hosseini et al 2019)
The potential gain from the UAV-assisted data gathering was found in
indiscriminate IoTs The characteristic propagation was represented by utilizing the
complicated channel method (contained small- and large-scale fading) IoTs were
updated in constrain of transmit power (in high) and total energy The multi-antenna
UAV was selected in the IoTs in sequence The virtual MIMO was created by the
communication between UAV and singe antenna IoT in every transmission (W
Feng et al 2018)
The UAV was applied in the aerial coverage surveillance agricultural prediction
constructional areas and power line supervising and blood donation The flight
26
period increment payload capability fast movement and speedy placements were
implied features in the UAV so that the UAV was exploited by the applications of
5G and B5G (Ullah et al 2020)
The UAV was considered a motivation for many emergent usages and reformed
social-economic welfares The wireless networks for the UAV and the base stations
were desired for the UAV function Mobile communications were considered
suitable for finding tracing and regulating the flying UAV The wireless
communications were selected for their features of broad coverage quality of
service and secrecy The wireless communication in the UAV improved
productivity besides the line of sight (G Yang et al 2018)
22 UAV-NOMA in Physical Layer Security enhancement
The NOMA has been applied in the fifth generation (5G) technology The Multicast
Cognitive Radio (MCR) network is implemented using the NOMA and coined as
MCR- MOMA The transmission side is also included with the superimposition
code The decoding was applied at the receiving end So an unknown user is
deduced in their methodology (Meng et al 2020)
The physical layer security for the cooperative NOMA was examined Amplify
and forward decode and forward were taken into consideration for achieving
secure transmission (Chen et al 2018)
The physical layer security of the NOMA was analyzed in the broader network with
varying locality The single and multi-antenna were established in the following
cases The single antenna was taken for an end-to-end connection in a secured
manner And the multi-antenna was used for the connection of base station and
random user Finally achieved security for the multi-antenna on the transmission
side The security of the single antenna was attained by introducing the excluding
area for eliminating eavesdroppers The individual expression of security outage
probability for both single antenna and multi-antenna were derived (Yuanwei Liu
et al 2017)
The secure transmission of NOMA in large-scale applications was investigated
Stochastic Geometry was utilized for placing the eavesdropper and user nodes The
equation for secrecy outage probability was derived and expressed for evaluating
27
secure transmission Security can be improved by expanding the protected zone
(Qin et al 2016)
The power domain NOMA had the disadvantage of decoding data by other
unauthentic users of the same source For reducing unauthentic users the base
station should treat the unauthentic users with different cleaning methods The
secrecy outage probability was investigated for authentic users and unauthentic
users Both users were combined as a pair to the non-uniform distribution of original
and unauthentic users The pair outage probability of genuine users from the secrecy
outage probability restrained NOMA authentic users The derivation for pair outage
probability and the secrecy probability were expressed for calibration The
combined system had been the better security (ElHalawany amp Wu 2018)
The physical layer security was considered problematic in the wireless networks
mainly for keeping the authentic userrsquos data The UAV was acted as the base
station UAV based base station had sent the extensive data to the original users
NOMA with the multi-antenna with mm-Wave frequency band transmission had
enhanced the spectral efficiency The physical layer security was attained by
announcing the space around user locality as the eavesdroppers protected zone
Covering the entire eavesdropper area was considered a resource-consuming way
The shape optimization for the protected location in each UAV base stations
altitudes was introduced The derivations for the secrecy sum rate and the secrecy
outage probability were expressed (Rupasinghe et al 2018)
The vehicular communication system had used cooperative NOMA The secrecy
outage probability was considered in vehicular communication The relay can be
used in both modes (half-duplex and full-duplex) in vehicular communication The
closed derivation for the secrecy outage probability was expressed The security of
the full-duplex NOMA resulted better than that of the half-duplex NOMA The
limitations are that the velocity of the vehicles was not considered Figure 21 is
illustrated the conceptual model of the vehicular communication NOMA system
(Xie et al 2019)
28
Figure 21 Vehicular communication NOMA system
The physical layer security of the uplink NOMA of the large-scale devices was
examined The connection networks had investigated with the approach called
stochastic geometry The new derivation was expressed for the coverage
probability The protected zone restrains eavesdroppers to the authentic users
Efficiency secrecy throughput was examined wiretap channels and the many
original users Constant transmission and variable transmission were collectively
inspected The signal to noise and the movement to interference ratio were derived
drastically (Gomez et al 2017)
The wireless system was executed using Space-Time Block Coding (STBC)
approach in the NOMA of mm-Wave MIMO The technique focused on haphazard
users So the pairing method was introduced mainly for Random Near-Random Far
(RNRF) Here the latent period could be minimized and the RNRF has also been
deduced for the overhead issue The result revealed the systems efficiency with a
proper implementation (Ghavidel et al 2020)
The recent arbitrary beam forming method was proposed in the multiple access
NOMA The pairing had decided to the user places So the evaluation was focused
on the system overhead The result revealed that the proposed work outperformed
29
the existing methods (Aghdam et al 2020) NOMA enhances the reliability of
multi-users transmission The sum rate could be reduced for improving Quality of
Service (QoS) power transmission and signal outage probability The
eavesdropper easily accessed the multi-access systems that cause physical security
during transmission (Z Li et al 2020)
The NOMA had provided spectral efficiency speed transmission of data multiple
networking and less latent period The NOMA utilizes the power domains for
various access Cognitive Radio Networks (CRN) is used to screen illegitimate
users The legitimate users were only permitted in the CRN by the Primary User
Networks (PUN) QoS The cooperative NOMA here implemented with the PUN
and the system performance is enhanced The spectral efficiency can be improved
by the secured transmission The cooperative NOMA was additionally developed
in the CRN with the PLS A new method of cooperative NOMA in the CRN was
examined The PUN technique attains a secure transmission Multiple antennae
were used in this study for reliability and the eavesdropperndashexclusion zone method
is used for better security (B Li et al 2018)
The downlink NOMA for moderate CSI was examined The challenge of the power
domain was rectified by allocating power NOMA The power in NOMA and that
of the OMA was analyzed which resulted in a significantly reduced NOMA (Cui
et al 2016)
Here the users were multiplexed by the power domain So the method was coined
as power domain NOMA The demand arising from the B5G (Beyond 5
Generation) had reached using power domain NOMA Machine learning in the
NOMA was described (Maraqa et al 2020)
The uplink NOMA with the PLS was proposed The uplink NOMA contained a
single base station and multi-users a couple of users combined for NOMA The
known jammer emitted the pseudo-noise to divert the eavesdroppers The study had
suggested the two jammers in the uplink NOMA for secure transmission (N Zhao
et al 2020)
The Intelligent Reflecting Surface (IRS) is designed using downlink NOMA The
multi-access had used the space direction of the beams of closure users The IRS
30
had performed the multi-access for every spatial order by the cell edge users of the
orthogonal beams (Ding amp Poor 2020)
The multi-input single-output NOMA has introduced the technique called Secrecy
Beam Forming (SBF) SBF had utilized the artificial noise for NOMA security
aided users in which the eavesdropperrsquos channels deteriorated The SBFs secure
transmission can be achieved in which high successive interference cancellation is
gained (L Lv et al 2018)
The superposition coding was performed in the transmission pat The successive
interference cancellation was conducted in the receiving position These two
techniques were combined in the novel 5G aided NOMA The basic concepts of
uplink and downlink NOMA were mentioned The dominant condition was
performed in the two user clusters of NOMA The prevailing state had issued the
confirmed spectral efficiency gain in NOMA (Tabassum et al 2016)
The relay scheme in IoT was examined for the secrecy of NOMA This was coined
as relay selection NOMA The base station had transmitted the secret messages to
the two NOMA-aided sensors and eavesdroppers IoT had treated the sensors and
eavesdroppers with different power allocations The expression for certain outage
probability and the strictly positive secure capacity was derived Increasing the
number of the relay would enhance the security in the NOMA-aided IoT The
outage probability for NOMA and OMA were compared The NOMA resulted in
better outage probability in Decode and forward mode (Do et al 2019)
31
Figure 22 RS-NOMA against an external eavesdropper
The NOMA-aided IoT was utilized to fight against the external eavesdropper as
Figure 22 The secured NOMA was proposed The base station sent secret
messages to several authentic destinationsmdashseveral eavesdroppers and unauthentic
users
Nakagami-m fading model was carried out using the multiple antennae in the
channel The security was attained using the max-min transmit antenna selection
scheme Both authentic and unauthentic eavesdroppers were analyzed The closed
derivation for the cumulative distribution of the original user was expressed first
That was compared with the unauthentic user The derivation for the secrecy outage
probability was obtained to identify the level of secrecy performance (Lei et al
2018)
Reconfigurable intelligent surface (RIS) aided NOMA was established for the
secrecy performance The main disadvantage of this model was the chance of using
RIS by the eavesdropper The secret outage probability was derived in this paper
The RIS improved the secrecy of the traditional NOMA The eavesdroppers were
limited from receiving the RIS signal by enhancing the number of intelligent
elements in the RIS A high signal-to-noise ratio was obtained from this experiment
(Liang Yang amp Yuan 2020)
32
The cooperative relaying NOMA was proposed for improving private transmission
in wireless networks Full duplex mode transmitted the jamming signals That
received the required communication at first Secondly the jamming signal
emission was sent by the base station The power allocation for the jamming signal
and information signal was decided on the eavesdropper channel state information
The eavesdropper was jammed by the signal from the first phase with maximum
power Second the derivation of the secrecy outage probability was expressed by
static eavesdropper CSI (Y Cao et al 2020)
The NOMA achieved spectral efficiency and secrecy The security of the multi-
NOMA users was obtained by the successive interference cancellation (SIC)
decoding in the receiving node The conservation of the untrusted NOMA was
concentrated in this study The security can be confirmed by the properly secured
decode processing and allocating power The decoding scheme was implemented
for aiding NOMA users The decoding was performed for enhancing the sum-rate
(Thapar et al 2020) The cognitive radio network in NOMA with the external
eavesdropper was proposed (Mehr et al 2020)
The cooperative NOMA was used in the field of energy harvesting communication
The novel relaying technique was introduced for achieving secrecy The secrecy
outage probability was derived and the derivation was expressed for the three
conditions The first condition was the derivation of CSI with a passive
eavesdropper The second condition was the derivation of CSI with the unauthentic
eavesdropper The third condition was the derivation obtained from the multi-relay
nodes The increased SNR resulted in high security The increase in the number of
users deduced security This was considered a disadvantage (Salem et al 2020)
Satellite communication covered more range of broadcasting So the security
challenge was considered a big difficulty in satellite communication Downlink
NOMA was assessed with an eavesdropper for the examination of secrecy The
paper concentrated on the physical layer security of downlink satellites Here two
methods were proposed The frequency-domain NOMA was considered for gaining
spectral efficiency The multiple user interferences were obtained in the process of
overlapping Introducing a suitable technique can be performed the security for the
number of users The secrecy rate was analyzed for all authentic users (and the
33
eavesdropper) and expressed in the derivation The safety was improved using the
spectral overlap method (Yin et al 2019)
The NOMA was considered as the emerging scheme in the upcoming wireless
networks The secrecy sum rate for the downlink NOMA (with MIMO multiple
inputs multiple outputs) was examined Downlink NOMA had the base station
number of users and the eavesdropper In the limitation of transmit power and
optimal successive interference cancellation the security was expected to enhance
Downlink MIMO NOMA was considered advantageous because of its secrecy
performance and the practical usage of bandwidth The mutual information rate and
the mean square error were causing the secrecy rate optimization to the problem of
biconvex This was rectified through the alternative optimization method and the
second-order cone programming was solved (Tian et al 2017)
Table 21 Comparative analysis
The comparative analysis for the physical layer security was examined in existing
studies
SR
No
Details of Author wise Contribution to NOMA Technology
1 Author (YFeng Yang amp Yan 2017) Secrecy performance in NOMA was
conducted with the help of artificial noise in the full-duplex mode of relaying
Methodology The optimization of the power was calibrated for the source
information and the noise signal The closed derivation for the secrecy outage
probability was expressed
Usage and limitations The physical security was increased
34
2 Author (He Liu Yang amp Lau 2017) NOMA was developed in the constrain
of security
Methodology The secret message had been sent to some users and also to the
eavesdropper The Novel decoding process was conducted for excluding the
unauthentic users The iterative algorithm was used for power optimization
Usage and limitations Transmit power was reduced The quality of service
was availed
3 Author (D Wang et al 2020) The secrecy was performed in the NOMA
The security was developed against the eavesdropper outside
Methodology The channel state information was analyzed for secrecy The
quantization of CSI had performed for secrecy The derivation for the secrecy
and transmission outage probabilities were obtained
Usage and limitations The secrecy rate was enhanced
4 Author (L Lv et al 2020) The physical security of the NOMA was
improved by adding artificial noise jammer and inter-user interference The
mode of full-duplex in the updated version was used in the NOMA
Methodology The eavesdropper can be trapped the superimposed signal from
the source So the secrecy was affected
Usage and limitations The spectrum usage is effective in the NOMA
transmission scheme Numerous connections can be performed in the NOMA
NOMA is considered to be the most advantageous for the upcoming
generation communications The superimposition technique was followed
4 Author (Yue et al 2020) Secrecy performance of the NOMA was developed
with a unique framework
Methodology The eavesdroppers inside the zone and outside the coverage
zone were examined properly in this paper The outage probability for codendash
power domain NOMA was derived
Usage and limitations Safety was acquired for both internal eavesdropper
and external eavesdropper in this scheme
35
5 Author (Guezouli et al 2020) The heterogeneous sensor network of cellular
communication was taken into account
Methodology Unmanned aerial vehicles are utilized the heterogeneous
sensor network of cellular communication
Usage and limitations Extended the life span of the network system The
cost of the hardware components is drastically low The random and the
repeats in the speedy movement The latency is maximized The coverage
period is maximum
6 Author (Yao amp Xu 2019) The security in transmitting a large amount of
information in the wireless network systems are analyzed with unmanned
aerial vehicle UAV
Methodology The numbers of UAVs are arranged in the space The base
station sent the information to the UAV in the space The authentic receivers
have obtained the secured information from the UAV The HPPP
homogeneous Poisson point process is used for distributing the authentic
receiver and eavesdropper in the line of sight
Usage and limitations The increase in the number of safety zone causing the
secured transmission
7 Author (Saacutenchez et al 2020) Physical security can be achieved by the
method of a unique encryption scheme
Methodology The physical layer security of the following schemes is
discussed in this paper mm-wave NOMA massive multi-input multi-output
heterogeneous sensor networks full-duplex mode
Usage and limitations The physical layer security was analyzed for the 5G
supporting technologies Good reliability achieved The less latent obtained
Machine-type communications can be enabled
36
8 Author (Hou et al 2018) The multi-antennas were used in NOMA with
UAV The stochastic geometric approach was examined
Methodology The multi-input multi-output kind of NOMA was utilized In
common the stochastic geometric approach was used for drastically moving
NOMA
Usage and limitations The maximum signal-to-noise ratio was obtained in
this scheme Power optimization was achieved The path loss is less Good
spectral efficiency was obtained
9 Author (Miao et al 2020) The broadcast type of communication was
performed The less weighed three-dimensional space for 5G communication
was analyzed
Methodology Both the performances of multicast and broadcast were
enabled UAV-assisted 5G communication systems are emerging in the
upcoming wireless networks
Usage and limitations Better flexibility in the network Continuous mobility
One lined line of sight
10 Author (Majhi amp Mitra 2020) The secure communication in cognitive radio
by NOMA was propounded
Methodology The antenna strategy of giving minimum outage probability
was concluded from this study
Usage and limitations The limitation is that more spectral efficiency causes
security issues
11 Author (X Zhao amp Sun 2020) Secure communication of the physical layer
in Visible light NOMA Communication was proposed
Methodology Energy optimization in security constrain was propounded for
achieving overall performance
Usage and limitations It is difficult to find optimal results because energy
optimization is the nonconvex issue
37
12 Author (Tuan amp Hong 2020) Secure communication in simultaneous
wireless information and power transfer NOMA was remitted
Methodology Eavesdropper is used for security purposes between the user
and base station using energy relays Known jammer is used for secure
transmission For energy efficiency storing and transferring were propounded
Usage and limitations Jamming requires extra power allocation
13 Author (Vaezi et al 2019) NOMA for 5G in mmWave MIMO cooperative
and cognitive were analyzed in this study
Methodology SWIFT NOMA is useful for weak receivers
MIMO using more antenna
Usage and limitations multi-antenna utilization cause high power
consumption
14 Author (Vaezi et al 2019) Mobile edge computing NOMA was proposed to
optimize power
Methodology Minimum latency and less power consumption
Usage and limitations Transfer power allocation must be calibrated
15 Author (Faraji-Biregani amp Fotohi 2020) Security in UAV communication
was proposed by introducing mobile agents
Methodology Malicious user of UAV was identified
Usage and limitations Three-phase power is essential
16 Author (G Zhang et al 2019) Secure communication in 5G UAV was
propounded by joint trajectory carrying out in physical layer
Methodology Power optimization was proposed for security
Usage and limitations Security in the physical layer was achieved by
optimization of trajectory
17 Author (Fotohi et al 2020) Agent-based self-protection was propounded in
UAN for secure communication
Methodology This method imitates the immune system of human beings
Less cost
Usage and limitations Energy is not optimized properly This approach
needs to consider other malicious attackers
38
18 Author (Shang Liu Ma amp Fan 2019) Vehicle to everything approach was
propounded for security in a UAV
Methodology Security of vehicle to the vehicle was proposed by considering
eavesdroppers active and passive attacks
Usage and limitations High price
19 Author (Kantor et al 2017) The flight path was calibrated in a UAV
Methodology Security performance was achieved by encryption as well as
anonymization
Usage and limitations High in cost and hardware structure occupies more
place
23 Research Methodology
The NOMA-based cellular architecture for UAV communication has been
considered here as reference network architecture Rayleigh fading has been
assumed as a channel characteristic The performance parameters for PHY layer
security are (1) Pair Outage probability (Pair OP) between two users trusted near
user designated as U1 and untrusted far user designated as U2) and (02) Secrecy
Outage Probability (SOP) of trusted near user designated as U1 The aim is to
achieve optimal Pair OP for the given constrained SOP of User U1 so that network
resources can be efficiently allocated to both users without compromising the
secrecy of trusted User U1
The mathematical analysis from reference literature (ElHalawany et al 2018) has
verified and supported the joint optimization of the Pair OP and SOP for the given
power allocation factor in NOMA This research work is extended as providing
more efficient resource allocation using the POMDP algorithm in a given scenario
First the varying distance of untrusted user U2 from BS as a critical selection
parameter that affects Pair OP amp SOP of user U1 and U2 both has been simulated
and the feasible and infeasible pairing of both users have been analyzed The
optimal power allocation factor for feasible pairing as the constrained problem is
optimized by opting for POMDP as a resource allocation algorithm wherein the
SOP of user U1 is strictly maintained for given CSI POMDP provides optimum
39
power allocation factor for trusted and untrusted users pairing as shown in the
proposed flow of POMDP algorithm is used to model a variety of real-world
sequential decision-making problems After the BS has been set up the distance
between the BS and the user is calculated and if space is less than 200m it is
defined as a trusted user While if the range is more than 200m it is described as
untrusted users In the case of trusted users the channel state information (CSI) is
provided to the proposed algorithm POMDP for reliable and efficient resource
allocation
24 Summary
UAVs play a central role in providing network service recovery in a disaster-
stricken region enhancing public safety networks or handling other emergencies
when Ultra-Reliable Low-Latency Communication is required In particular UAV-
assisted communication can be regarded as an important complement to the 5G
cellular networks Surveyed literature related to UAV communications published
over the past several years emphasized the cybersecurity and channel modeling for
UAV communications etc Security is one of the critical issues in communications
Modern communication networks are based on the layered architecture from the
physical layer up to the application layer A great deal of effort has been made to
develop the cryptographic protocols above the physical layer However the
physical layer is not as robust as that in wired communications The physical layer
in wireless communication is more complex than the counterpart in other
communication paradigms The concerns come from not only the noises but also
many types of fading Recently there has been an influential interest in studying
the security issues in the physical layer Security is highlighted as another
challenge and the implementation of physical layer security techniques is seen as
a difficult task PHY security in NOMA systems under the presence of external
eavesdroppers or untrusted relay nodes Upcoming 5G networks for unpredicted or
crisis (disaster management) the placement of terrestrial substructures is
economically infeasible and challenging due to high operational expenditure as well
as sophisticated and volatile environments
To address such novel issues intelligent heterogeneous architecture by leverage
UAV has been well-thought-out to be a promising novel model For advancing the
40
performance of the UAV 5G communication system physical layer techniques are
of many effects as they have impacted the applications of UAVs Security of
NOMA-based UAV communication network has been scrutinized for optimization
as physical layer security
41
CHAPTER-3
SYSTEM MODEL FOR NOMA-UAV
COMMUNICATION
31 NOMA-UAV System Secured Communication for 5G
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
311 The basic scheme of NOMA
The NOMA system allowed several users to be served simultaneously by the
transmitter To transfer a linear combination of different signals towards the
recipient the system of proportional representation superposition coding (SC) The
transformed signal is provided through
σ ඥ119875119896 119878119896119870119896 =1 -------------------------------------- (1)
Where 119927119948 represents the transmit power assigned toward user k th
119930119948 indicates the normalized message used for user k th
42
The instantaneous total converses power is σ 119927119948119922119948=1 The received signal at user kth
and the eavesdropper are offered through
119910119896 = ℎ119896 σ ඥ119875119896 119878119896119870119896=1 + 119899119896 -------------------------- (2)
119910119890 = ℎ119890 σ ඥ119875119896 119878119896119870119896=1 + 119899119890 -------------------------- (3)
Where 119951119948 and 119951119942 indicated the zero-mean Additive White Gaussian Noise
(AWGN) at user k th with variance 1205901198962 and the zero mean AWGN at eavesdropper
with variance 1206481199422 respectively We assume that the noise variances at all the users
are identical
ie 12059012 = ⋯ = 120590119896
2 = 1205901198902
As per NOMAs process the SIC is followed by all users to decrypt the message to
the same decoding order Notice that it is not known what the optimal decoding
order is for the NOMA method that corresponds to secrecy
Therefore the mth message to be encoded to the user might not be the mth message
to the user As such we also have to add the π variable For example if 120587(1) =
3 then the first message to be decoded for the SIC is the message for the user 120645(119947)
forall j lt k before decoding its letter to remove the inter-user interference successively
Then the user 120645(119948) denotes its message while treating the news for all the user
120645(119946)foralli gt k as the interferences The received Signal-to-interference-plus ndashnoise
ratio (SINRs) at user 120587(119896) k lt K and user 120587(119870) to decode their messages are
respectively given by
119878119868119873119877120587119896=
120574120587(119896)119875120587(119896)
1+120574120587(119896) σ 119875120587(119894)119896119894=119896+1
119896 lt 119870 --------------------(4)
119878119868119873119877120587119870= 120574120587(119870)119875120587(119870) --------------------------------------(5)
Were 120574120587(119896) =หℎ120587(119896)ห
2
1205901199062
൘
43
Also the acknowledged SINR at user 120587(119898) to decrypt the message 120633120645(119948) 119896 lt
119898 le 119870 is given by
119878119868119873119877120587119896=
120574120587(119898)119875120587(119896)
1+120574120587(119898) σ 119875120587(119894)119896119894=119896+1
kltmle 119870 --------------(6)
Similarly the acknowledged SINRs by the eavesdropper of the message 120575119896 119896 lt
119870 and the message 120575119896 are respectively given by
119878119868119873119877120587macr
119896=
120574119890119875120587(119896)
1+120574119890 σ 119875120587(119894)119896119894=119896+1
klt119870 ----------------- ------(7)
119878119868119873119877120587macr
119896=
ȁℎ119890ȁ2119875120587(119896)
1205901198902 = 120574119890119875120587(119896) klt119870 ---------------------(8)
Where 120574119890=ȁℎ119890ȁ2
1205901198902൘
Notice that here expressions for the obtained SINRs at eavesdropper overestimate
the skill of eavesdropper Here a worst-case inference from the viewpoint of
legitimate users is made That is the messages have already been decrypted by the
eavesdropper for all users π (j) forall j lt k before attempting to decrypt the message
for the user π (k)
The presumption also assumes that the decrypting order and power distribution are
understood by the eavesdropper The eavesdropper may or may not recognize the
decoding order of the users and the allocation of power may or may not recognize
the messages for all users π (j) forall j lt k before attempting to decode messages for
users π (k) However since the eavesdropper has been unable to alert the authorized
customers of its capacity and the current CSI the approved user would be unable
to know the eavesdroppers details Therefore we have to pursue the worst-case
scenario for the permissible users point of view due to the liberality required by the
safety reports It highlights that the worst-case assumption in the study and design
of transmission schemes with secrecy requirements has been generally adopted
The proposed study has been evaluated using performance measures Here we
analyze NOMA with downlink and uplink networks suggested by SINR and Sum
44
Rate survey High SNR is then simulated to contrast the OMA and NOMA
processes
312 Downlink of NOMA
The Downlink of the NOMA network on the transmitter side is described in Figure
31 SIC method is supposed to be carried out successively on the receiver side of
each user until another signal is restored The coefficients of users are owed in an
inversely proportional manner based on their available bandwidth
Figure 31 Downlink NOMA network
A consumer with a poor available bandwidth has a transmission capacity of a
higher range than a consumer with strong available bandwidth As a consequence
the consumer with the higher power assumes the signals of other users to be noisy
and automatically restores the signal without conducting any SIC operation The
receiver of each consumer detects indications that are stronger than those of the
desired signal These impulses are then deducted from the power and this process
continues until the signal has been calculated Both users decrypt their signaling by
considering other users with lower correlations The signal is calculated as
45
119904 = σ 119886119894119875119904119883119894119871119894=1 -----------------------------------------------(1)
Where Xi is the user ithrsquos information through unit energy
Ps is the capacity of transmission at the BS
ti is the coefficient of power assigned for user i
Although without the need for lack of generality the channel profits are expected
to be graded as ȁℎ1ȁ2 le ȁℎ2ȁ2 le ⋯ ȁℎ119871ȁ2
Where 119945119923 is the coefficient of the channel of the user Lth
The received signal of the Lth user is calculated as
1199101 = ℎ119897119904 + 119899119897 = ℎ119897 σ ξ119886119894119875119904119883119894119871119894=1 + 119899119897 -----------------------------(2)
Where n1 is zero mean Complex Gaussian noise with a variance of 1206482SINR
analysis with the equation (2) the SNR of Lth user to identify the user 119895 le 1with
119895 ne 1
119878119868119873119877119871 = 1198861120574 ȁℎ1ȁ2120574ȁℎ1ȁ2൘ σ 119886119894 + 1119871
119894=119871+1 ------------------------(3)
Where 120632 = 1198751199041205902ൗ represents the SNR
Sum rate analysis After identifying the SINR of the downlink the sum rate will
also be done quickly
The NOMAs downlink data rate of Lth user can be calculated as
1198771119873119874119872119860minus119889 = 1198971199001198922(1 + 119878119868119873119877119871) --------------------(4)
313 Uplink of NOMA
The Uplink NOMA is depicted in Figure 32 where each user sends a signal to the
BS SIC iterations are supported to classify the signals of mobile users If both
channels are identical and BS sends the coefficients of power allocation to mobile
users the received signal can be interpreted as a synchronous uplink to the NOMA
46
119955 = σ ℎ119894ඥ119886119894119875119909119894119871119894=1 +n ----------------------------------(5)
Where hi is the coefficient of the channel for the ith user
119927119961119946 is the extreme transmission capacity supposed to be general to all users
N is zero-mean Gaussian noise with a variance of 1206482
Figure 32 Uplink NOMA
Analysis of SINR The BS decrypts the signals of the users as per the coefficients
of the users and the SINR for the Lth user can be defined as
119878119868119873119877119871 = 119886119897120574ȁℎ119897ȁ2120574 σ 119886119894ȁℎ119894ȁ2 + 1119897minus1
119894=1൘ ----------------------------(6)
Where 120574 = 1198751205902ൗ indicates SNR
Analysis of Sum rate The sum rate of uplink NOMA when 120632 minus infin can be
computed as
119877119904119906119898119873119874119872119860minus119906 asymp 1198971199001198922(120574 σ ȁℎ119897ȁ119871
119894=1 2 ------------------------ (7)
47
314 Comparison of NOMA and OMA
The attainable data rate of the Lth user of OMA intended for both uplink as well as
the downlink is estimated as
119877119904119906119898119874119872119860 = σ 120572 1198971199001198922120574(1 +
120573119897ȁℎ119897ȁ2
120572119897119871119894=1 ) --------------------------(8)
Just for convenience two users should evaluate the summation of uplink rates for
NOMA and OMA The use of both the uplink rate of NOMA and OMA at high
SNR can be calculated as---
119877119904119906119898119873119874119872119860 asymp 1198971199001198922(120574 ȁℎ1ȁ2 + 120574ȁℎ2ȁ2 ------------------------- (9)
equation (7) and (8) it is seen that 119877119904119906119898119874119872119860 le 119877119904119906119898
119873119874119872119860
Here we note 119929119956119958119950119926119924119912 le 119929119956119958119950
119925119926119924119912 shows that NOMA performed better than OMA in
terms of sum rate in both downlinks as well as uplink of two user networks
The sum rate will be calculated after the SNR as the formulation is shown In this
proposed work multiple users are propagated to the process of NOMA and here a
comparison of NOMA as well OMA has been defined The NOMA uplink and
downlink using the OFDMA method for the
32 PLS performance metrics in NOMA -UAV communication
This chapter mainly describes the proposed work to examine the availability of the
outage probability of the pair below an authorized user According to the decryption
of SIC availability and spectrum sharing the unauthorized user can function as an
eavesdropper and obtain an outage probability (OP) for all situations with the
Secrecy Outage Probability (SOP)
321 SOP and OP - two user and multi-user NOMA system
NOMA system has the capability for assigning multiple data over the transmission
signal through high-level coding (Shim amp An 2018) Thus it contains spectrum
efficiency when opposed to OMA But this has a limitation in security As an
48
instance if the eavesdropper is reached then it obtains multiple user data in the
interference of the NOMA signal Thus the security issues are more significant in
this system Here PLS is an available method to rectify the attack intended for
malicious users (Dai et al 2015)
Additionally data should be transmitted confidentially if the root and eavesdropper
networks can be evaluated and the recipient can decrypt the received text At the
same time the eavesdropper is not able to solve the text that has been interrupted
PLS is at the cutting edge of wireless communication security technology to prevent
eavesdropping attacks The SOP is described as the likelihood that the near users
attainable device confidentiality capability will fall under the predefined target
confidentiality rate as set out in (Shim et al 2017)
Through SOP we can calculate the level of protection of the device As an example
the low-secret OP system makes the system more stable in terms of security than
the high SOP system To boost the efficiency of the PLS CSI-based opportunistic
scheduling links to a scheduled destination in a particular time slot It has been
documented as an enticing scheduling scheme (Long Yang et al 2016) because the
various wireless channel has been exploited Opportunistic scheduling is also
considered to be one of the strategies used to increase the confidentiality efficiency
of the NOMA method
322 System Model
Suppose a multi-user NOMA system of downlink containing BS a selection of K
nearer users as N= 119873119894ȁ12 119870 and a range of M far users as F=
119865119895ȁ12 119872 and an eavesdropper E as displayed in Figure 33 More
specifically nearer users should make active use of the SIC methodology to
distinguish far user F Both the legitimate and illegitimate receivers are furnished
through a single antenna and operate in a half-duplex manner
49
Figure 33 Multi-two user architecture of NOMA system (Shim amp An 2018)
Here 119945119935119936 and ȁ119945119935119936ȁ2
Where X120598ሼ119878ሽ 119884120598119873 cup ሼ119864ሽ represent the channel coefficient and the corresponding
channel gain of the X-Y value
Taking into consideration that each wireless channel for Rayleigh block fading 119945119935119936
can be incorporated as an independently distributed random Gaussian variable with
zero mean and affirmative ℷ119935119936 Variance The outcome of channel gain ȁ119945119935119936ȁ2is an
exponential variable randomly through the Probability Density Function (PDF)
119891ȁℎ119883119884ȁ2(119911) = ቀ1
ℷ119883119884ൗ ቁ 119890119909119901 (minus 119911
ℷ119883119884ൗ )
if zge 0 119900119905ℎ119890119903119908119894119904119890119891ȁℎ119883119884ȁ2(119911) = 0 -----------------(1)
Especially the average channel profit can be represented as
ℷ119883119884= ൬119889119883119884
1198890൘ ൰
minus휀
ℒ ------------------(2)
When 120027 is the attenuation of the received signal 119941119935119936 signifies the distance among
X and Y 1199410 indicates the space and 120656 is the exponent of the path loss It is believed
that the source is entirely familiar with the CSI of both legitimate users and
eavesdroppers
50
323 Partially Observable Markov Decision Process-POMDP
Figure 34 Flow Diagram of the proposed system
The proposed overflow is shown in Figure 34 After the BS has been set up the
distance between the BS and the user is calculated and if space is less than 200m
it is defined as a trusted user While if the range is more than 200m it is described
as untrusted users In the event of untrusted users the channel state information is
accessible to the POMDP accompanied by the allocation of resources The study
was carried out after the machine operation Here a NOMA-oriented cellular setup
provided with a BS at the Centre and two users was described in Figure 35
51
Figure 35 Near and Far User
The adjacent user has a high level of security confirmation needed to protect the
layer since the low-security clearance user is situated at a distance away from the
BS P is specified as the highest level of transmitting power In this chapter it is
presumed that all DNS servers are furnished utilizing an individual antenna and all
channels are supposed to be individually static identical to the Rayleigh
dissemination concerning distribution
119862119873(0 120575119898
minus120572
212059601 2Τ
)
In which 120633119950 is the range between the BS and the nodes 119932119950 Here the path-loss
exponent and constant are defined as 120630 and 1206540 Furthermore BS is assumed to
have predicted the position of the user so that a better CSI can be obtained at BS
that is elaborate in user pairing
The BS transmits the superimposed mixture
119909119905 = ඥ1199051199041 + ඥ1 minus 1199051199042 ------------------------------- (3)
In which 1199561 and 1199562 are the unit of power signals received by users 1199321 and 1199322
respectively t is the power allocation coefficient for the adjacent user
1199031 = ℎ1119909119905ξ119875 + 1198991 ------------------------------- (4)
1199032 = ℎ2119909119905ξ119875 + 1198992 ----------------------------------(5)
Where 1199451119886119899119889 1199452 the channel profit link with the fading of small scale since the
BS to the user 1199321 and 1199322 respectively The additional Gaussian noise with variance
52
is denoted 1199511 119886119899119889 1199512 and zero mean 119894119904 119889119890119899119900119905119890119889119886119904 (1199250) and it is assumed
that the BS conveyed SNR is 120646 = 1199271199250
ൗ
In the NOMA technique additional users with more power may decode their signal
by recognizing the adjacent signal as noise without decoding the adjacent user
message In the previous equation 1198801 is supposed to first solve a weak signal by
decoding its own SIC signal1198802 which is an unauthenticated user attempted to
decrypt the nearer user text after decrypting the adjacent usage text after decoding
its own SIC message The following equation has therefore been achieved
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2 ----------------(6)
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2 ----------------(7)
119879119900119905119886119897119904119894119899119903 = 11987811986811987311987721 1198781198681198731198771
1 119878119868119873119877221198781198681198731198771
2 -----------------(8)
Where 119930119920119925119929119950119951
indicates the SINR ratio of user mth that was decoded by 119932119951 for
119898 119899 isin ሼ119894 2ሽ and the channels gain followed an exponential distribution with the
parameter 120649119950=120654120782120633119950minus120630
324 Problem formulation
As a result the BS could achieve and provide better communication for users who
are vulnerable to security threats from unauthenticated users the proposed
framework identified two kinds of QoS energy efficiency that could be considered
essential for addressing the problem In a particular study a pair of OPs was
specified to check the reliability at which the attainable data rate for users is equal
to or greater than the threshold of minimum reach The following issue aimed at
reducing the pair OP to an SOP factor intended for the user 119932120783 that is provided by
Where 1199270is Outage Probability- (OP)
1199271 is Secrecy Outage probability user U1 119930119926119927(119932120783) and
120631 the permissible SOP threshold
53
33 Performance Analysis Improving PLS Insecurity of NOMA
System
331 The Pair OP Calculation
Through Shannons capacity formula and assuming 119914120783119957119945 119886119899119889 119914120784
119957119945 as the
threshold capacities of users 119932120783 119886119899119889 119932120784 respectively the combination of OP
could be offered by
119927119954 = 120783 minus 119928120783119961119928120784 in which 120649119950 = 120784119940119950119957119945
119950 isin ሼ119946 120784ሽ -------------(9)
empty120783 =120649120784
120646(120783+119957+120649120784119957) empty120784 =120649120783
120646119957
119928120783 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ 120782 lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 ------------------------(10)
Case 1empty1 gt empty2 for having the limitation of the allocation of power factor (t)
required to be satisfied (tgt120649120783
120649120783+120649120784+120649120783120649120784) and for this case 119928120784 could be attained as
follows
119928120784 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ
120649120783
120649120783+120649120784+120649120783120649120784lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 --------------(11)
Case 2 empty1 lt empty2 Like case 1 it was stated that the opposite constraint depends
on
t gt 1206491
1206491+1206492+12064911206492 and 1199282 can be evaluated as follows
119928120784 = ൝119942119961119953 ቀ
minusempty120784
120649120783ቁ 120782 lt
120649120783
120649120783+120649120784+120649120783120649120784
120782 119952119957119945119942119955119960119946119956119942 ---------------------(12)
54
Table 31 List of parameters
Parameters Description
N Number of nearer users
M Number of far users
E Eavesdropper
ℎ119909119910 Channel coefficient between 119909119905ℎchannel and 119910119905ℎ users
119889119883119884 The distance among x and y
1198890 Space
120598 An exponent of the path loss
ℒ Attenuation of the received signal
120575119898 the range between the BS and the nodes
1205960 Path loss constant
120572 Path loss exponent
1199041 1199042 Unit of power signals received by users 1198801 and 1198802
T Power allocation factor for the adjacent user
ℎ1119886119899119889ℎ2 Channel coefficient of 1198801 and 1198802with the fading of small
scale
11989911198861198991198891198992 Gaussian noise variance
1198730 Zero mean for Gaussian noise
120588 Signal to noise ratio
119878119868119873119877119898119899
Signal to interference noise ratio of users n and m channels
55
120591119898 Exponential distribution parameters
1198750 Pair of OP
1198781198741198751 119878119874119875(1198801)
120573 The permissible SOP threshold
Table 31 depicts the list of parameters used in the proposed methodology which
are useful for assigning and the values are assigned based on the parameters given
for the experimental evaluation as well This chapter concludes with the basic and
the actual flow of the proposed method to know more about the work in the
simulation process
332 Pseudo-code for the proposed algorithm
Algorithm I
Step 1 Estimate Rayleigh distribution
119862119873(0 120575119898minus120572 2Τ
1205961199001 2Τ
) where
120633119950 is the distance between nodes 119932119950 and the BS
120630 is the path-loss exponent and
120654119952 is the path-loss constant
Step 2 The BS broadcasts the superimposed mixture and input signal as follows
119909119905 = ξ1199051199041 + ξ1 minus 1199051199042
Where 119956120783 and 119956120784 are the unit power signals received by users 119932120783 and 119932120784
respectively 119957 is the Power allocation coefficient for the near user
Step 3 The received signal is as follows
1199031 = ℎ1119909119905ξ119875 + 1198991
1199032 = ℎ2119909119905ξ119875 + 1198992 where
56
119945120783 and 119945120784 are the channel gain associated with the
small-scale fading from the BS to users 119932120783 and 119932120784 respectively
1199511 and 1199512 are the additive white Gaussian noise with zero mean and variance
119925120782
Step 4 the BS transmit signal-to-noise ratio (SNR)
120646 = 119927119925120782
Step 5 Signal-to-Interference-plus-Noise-Ratio (SINR) for the two users 119932120783
decodes the signal of the weak user first then decodes its own signal after using
SIC 119932120784 is an untrusted user and tries to decode the near user message after
decoding its own message using SIC
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588ൗ and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ2ȁ2+1120588ൗ and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2
119879119900119905119886119897119904119894119899119903 = ሼ11987811986811987311987721 1198781198681198731198771
1 11987811986811987311987722 1198781198681198731198771
2ሽ
where 119930119920119925119929119950119951
is the signal-to-interference-plus-noise-ratio (SINR)
of user 119950th decoded by 119932119951 for 119898 119899120598ሼ119894 2ሽ and ȁ119945119950ȁ2 is the
channels gain of 119932119950
Algorithm II
Partially observable Markov decision process
Step 1 Prediction of the maximum capacity of channel with respect to the data rate
119955119943 = 119877(119878119909119863)
S is denoted as states
Let D be the channel characteristics which are considering here as actions
Reward function R
Step 2 The agent receives an observation 119900120598120118which depends on the new state of
the environment 119930prime and on the just taken action 119941 with probability
119926(119952ȁ119956prime 119941)
Step 3 Reward earned at time t is expressed as
57
119903119891119905 = 119877(119878119909119863)119905
Step 4 reward function on belief states
119919 is the belief states over POMDP states
119919119943 is the belief state transition function
119955119943 = 119877(119867119909119863)
Step 5 The reward function is updated based on the belief MDP the agent only
cares about which action will yield the largest expected immediate reward ie the
maximum capacity channel
119861119891 ቀℎ 119889 ℎprimeቁ = 119875119903 (
119900120598120118
ℎprimeȁℎ 119889 119900) 119875119903(119900ȁ119889 ℎ) 119861119891
119875119903(ℎprimeȁℎ 119889 119900) = ቄ1119894119891119905ℎ119890119887119890119897119894119890119891119906119901119889119886119905119890119908119894119905ℎ119886119903119892119906119898119890119899119905119904ℎ 119889 119900119903119890119905119906119903119899119904ℎprime
0119900119905ℎ119890119903119908119894119904119890
119903119891(ℎ 119889) = σ ℎ(119904)119877(119904 119889)119904isin119878
34 SUMMARY
The NOMA-UAV communication framework has been proposed in this research
work and the Physical Layer security aspect has been focused on for optimization
The PLS performance metrics selected are SOP amp Pair OP in the proposed system
model The POMDP framework is general enough to model a variety of real-world
sequential decision-making problems Applications include robot navigation
problems machine maintenance and planning under uncertainty in general Here
we have adopted the User pairing POMDP algorithm for resource allocation in two
users amp multi-user NOMA-UAV communication networks The proposed study has
been evaluated using performance measures by varying distances of trusted amp
untrusted users from the base station as well as for varying SINR conditions The
simulation results and outcomes are discussed in a further chapter
58
CHAPTER 4
RESULT AND DISCUSSION
41 PERFORMANCE MEASURES OF SECURED NOMA-
UAV COMMUNICATION MODEL
Drones or UAV-based communication technology has been thoroughly studied and
adopted by the 3GPP standard UAV systems have been envisaged to form an
integral part of future wireless communication applications due to their dynamic
flexible and flying nature Due to their ability to reach higher altitudes they usually
have dominant LOS channels with the ground nodes This capability can be used to
provide confidentiality to the legitimate receivers against the eavesdroppers This
can be done by deploying UAVs to launch more effective jamming signal attacks
to terrestrial eavesdroppers The conventional cooperative jamming schemes make
an assumption that the locations of terrestrial jammers are fixed which might
compromise the secrecy of the system if the jammers are located far away from the
eavesdroppers and is also not practical as it makes an assumption of perfect CSI of
the jammer to eavesdropper channel
Here in the proposed scenario of the NOMA-UAV communication network two
key PHY layer security metrics SOP amp Pair Outage Probability have been jointly
optimized for a more effective power allocation factor for NOMA cellular
architecture The varying channel characteristics have been analyzed to achieve the
desired SOP with the constrained threshold minimum target secrecy rate for the
two-user scenario POMDP Algorithm iteratively provides the optimized SINR that
has been used to keep trusted users in pair with the untrusted user with minimum
achievable outage probability
The proposed NOMA-UAV System model has been simulated in MATLAB 2019b
version with mainly Communications System Toolbox Optimization Toolbox RF
Toolbox Signal Processing Toolbox Statistics and Machine Learning Toolbox
The simulation has been carried out for two-user pair to achieve desired secrecy
target rate and feasible pairing between trusted user amp untrusted user(eves-dropper)
59
The optimal-outage performance of minimized pair OP subjected to SOP constraint
has been solved by both dynamic programming optimization and POMDP
optimization approaches
The simulation of the proposed framework for the UAV-NOMA communication
network has been carried out and discussed in two parts two user models and a
multi-user model as below mentioned discussion The base station is deployed at
the center of a cell of radius 1000 m There are two users in the system under
consideration The channel between two nodes in the system suffers both the small-
scale fading and path loss effect Small-scale fading follows the exponential
distribution with the mean value 1 The noise signal of all channels has a Gaussian
distribution with 0 mean and variance 1 The path loss exponent α and the path loss
constant PLo are set to 2 and 01 respectively We assume a normalized bandwidth
of 1 Hz The SOP constraint threshold is assumed 01 and the target secrecy rate is
001 The power allocation coefficient is 015 and the BS transmitted SINR is
assumed 15dB for the proposed model As per the NOMA transmission scheme
SINR has been obtained for User 1 amp User 2 both for SIC decoding POMDP
algorithm optimally tunes the SINR value for User 1 amp User 2 that is considered to
select optimal power allocation coefficient for both trusted and untrusted users with
respective SOP of User1
42 Numerical results and Discussion
Table 41 Simulation Parameters
Parameters Values
Untrusted user Distance (d2) 200-1000 (300 700)
BS transmit signal-to-noise ratio (SNR) (120588) in dB 15
Sop constraint constant threshold (β) 01
Power allocation factor (t) 015
Trusted User distance (d1) 2-
60
Cell Radius (rd) 1000 meters
Path loss exponent (α) 2
Path loss constant (PLo) 01
Normalized bandwidth in Hz 1
Target secrecy rate (Rs) 001
No of Bits 100
Pair Outage Probability (P0) 05250
SINR 5319 15305 5162
10247
421 Feasible amp Infeasible pairing of trusted amp Untrusted users
In this section the CSI value broadcasted by Base Station is assumed 15 dB initially
and for varying channel conditions various SINR values of 120646 = minus20 minus10 20 dB
is described with target secrecy rate 0005 and 001 for power allocation coefficient
015 and User 1 distance at 200m is shown in the Figure 41 below
Figure 41 Impact on Sop with increase distance between BS and user U2
61
Varying target secrecy rate threshold from 0005 to 001 the obtained result in
Figure 42 revealed that the 1199321 is a gradually reducing function for the distance of
untrusted user d2 that implies that the increasing value of d2 leads to the
improvement of the SOP of 1198801
Figure42 Impact on Sop with increase distance between BS and user U2
Since the offered constant threshold 120656 in SOP limit1199322 which should be located at
a larger space when compared with a value of threshold to attain the SOP of 1199321
apart from that it is expected the high target secrecy rate maximizes the SOP of 1199321
Here in below figure the power allocation coefficient has been varied from 0 to 1
with threshold value of t and the desired t_sop for feasible pairing
Figure 43 Feasible pairing t Vs pair OP
62
Pair OP in case of rising 1199322 untrusted user in d2 for different BS transfer the SNR
where t= 015 and d1=200mThe infeasible pairing of SOP (1199321) and the OP pair
by the enhanced allocation of the power (t) d1 (200m) d2 (300m) 120646 = 15 dB and
120656 = 0
Figure 44 shows the identical plotting of data by adjusting the unauthenticated
level of the user through converting it to a BS closer distance (d2=300m) Accuracy
is compared and checked with the full spectrum of numerical simulations The
result has shown that the effectiveness is based on a comparative study of the two
consumers of the BS
Figure 44 Infeasible pairing t Vs pair OP
422 The Secrecy Outage Probability amp Pair Outage Probability
Feasible paring in the SOP of pair OP and 1199321 with the improved power allocation
factor t in which d2=700m d1=200m 120646 = 15119889119861 and The result described that
the OP and SOP of the user 1199321 with increased for two various distances of the 1199322
untrusted user The simulation result approves the convex nature 120656 = 0 1of the OP
and the SOP is sequentially decreased depending on t Generally when it enhances
the power owed to the weak user text reduces that develop the ability of 1198802 for
discerning the superior positioned signals therefore enhancing the SOP of 1198801
63
Figure 45 Secrecy outage probability
Figure 46 Pair outage probability
423 SNR versus Strictly Positive Secrecy Rate
Figure 47 proved that the potential for confidentiality is superior to the existing
techniques The proposed application for pre-coding improves the efficiency of the
device The transmission power of the system is the power needed for the
transmission of particular data
64
Figure 47 SNR versus Strictly positive secrecy rate
If there is a growth in the number of users there is a risk of inference in the
transmission of data and thus the reliability of the data rate may be affected Based
on these cases the efficiency of the antenna power to be withheld and occupy the
data determined
424 Power radiated by per MMBs antenna
In the case of multi-users scenario when there are more than two users then the
allocation of an optimized resource block to all users is the key parameter to achieve
desired outage efficiency because strong users require higher SNR for higher data
rates and weak users are allocated minimum threshold SNR for lower data rate
requirements to maintain suitable pairing OP and SOP balance
Figure 48 Power radiated by per MMBs antenna
65
So the POMDP policy optimization has shown better performance over the
dynamic programming approach particularly when more users are active (a greater
number of antennas as in Figure 48 the overall radiated power per BS antenna in
downlink has been considerably reduced
43 CONCLUSION AND SCOPE OF FUTURE WORK
431 Conclusion
Starting with LTE (4G) OFDMA has replaced WCDMA with mobile cellular
communications and will also be used during advanced 5G while Non-Orthogonal
Multiple Access (NOMA) has recently been recognized as a groundbreaking PHY
technology in UAV communication NOMA scheme is used in place to increase the
effective use of small resources such as in UAV communication where the data rate
is very low and critical decision making is of utmost importance
The critical need for UAV communication is a secure PHY layer for mission-
critical applications and as NOMA doesnrsquot promise high security the proposed
research work has been carried out to enhance the insecurities of NOMA-UAV
communication In this proposed research work the probabilities of confidential
outage (SOP) and OP were investigated in the two-user NOMA system Here BS is
required to pair a trusted or permissible user with other untrusted users due to the
unequal distribution of untrusted and trusted users in the cell The SIC is then
applied to the receiver side intended for decoding the message signals The Pair OP
of both users has been analyzed for varying Target Secrecy Rate (Rs) of the trusted
user U1 which provides constraint threshold of the SOP of U1
By varying the distance of Untrusted users from BS the optimal distance and power
allocation factor for the feasible pairing of trusted and untrusted users without
compromising the secrecy outage probability of U1 has been achieved in simulation
results
POMDP has provided the optimal power allocation as a resource allocation
algorithm in the dynamically changing environment of two user NOMA cases
where the distance between BS and untrusted user varies significantly The
performance of secure NOMA-UAV is affected critically by (SOP of User 1) which
66
should be optimally selected to maintain the proposed Pair OP between both users
and the simulation results have supported this optimal outage performance Thus
NOMA-UAV architecture has the potential of providing a secure PHY layer for
mission-critical applications by opting for suitable decision-making resource
algorithm POMDP
431 Scope of Future Work
Furthermore the multiuser scenario with the increased number of Untrusted users
can be analytically verified and simulated in the same direction for NOMA-UAV
communication to improve transmission security and reliability In addition more
adaptive and efficient Resource allocation algorithms for NOMA-UAV networks
with secured performance in real-time applications should be investigated
1
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11
PUBLICATIONS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495449|P a g e
Migration from 4g LTE to Advanced PHY Techniques for
Unmanned Aerial Vehicle (UAV) Communication
Pankaj Patel PHD StudentGujarat Technological UniversityGujarat India
ABSTRACT
UAV (unmanned aerial vehicles) with their high mobility and low cost have found a wide range of applications
during the past few decades Historically UAVs have been primarily used in the military mainly deployed in
hostile territory to reduce pilot losses With continuous cost reduction and device miniaturization small UAVs
are now more easily accessible to the public hence numerous new applications in the civilian and commercial
domains have emerged For the sake of boosting resilience against faults natural disasters and unexpected
traffic the Unmanned Aerial Vehicle (UAV) assisted wireless communication systems can provide a unique
opportunity to cater for such demands in a timely fashion without relying on the overly-engineered cellular
network However for UAV-assisted communication issues of capacity coverage and energy efficiency are
considered of paramount importance Starting with LTE (4G) Orthogonal Frequency Division Multiple Access
(OFDMA) has replaced WCDMA for cellular mobile communications and it will also be employed in advanced
5G yet Non-orthogonal multiple access (NOMA) has been recently recognized as a promising PHY technique
to significantly improve the spectral efficiency of mobile communication networks In this paper we provide an
overview of UAV-aided wireless communications by introducing the basic networking architecture
highlighting the key design considerations as well as the new opportunities to be exploited
Keywords LTE (4G) Non-orthogonal multiple access (NOMA) Unmanned Aerial Vehicle (UAV) Wireless
communication
----------------------------------------------------------------------------------------------------------------------------- ---------
Date Of Submission 26-04-2019 Date Of Acceptance 06-05-2019
----------------------------------------------------------------------------------------------------------------------------- ----------
I INTRODUCTION The use of unmanned aerial vehicles
(UAVs) will grow rapidly in the next decade These
remotely piloted or preprogrammed aircraft are
envisioned for applications in numerous civil
settings including industrial monitoring scientific
data gathering agriculture public safety and search
and rescue Many other applications - presently
unforeseen - will inevitably also arise These
vehicles also known as the unfortunate misnomer of
drones must be integrated into the national
airspace system and into the airspace worldwide A
natural concern in the use of UAV is safety and this
has direct implications for the control and non-
payload communication systems that must be used
to operate it efficiently Similarly navigation and
surveillance functions must be made more reliable
and more accurate Because of these factors many
UAV research development testing and
standardization efforts are underway by
governments industries and academia Despite the
fact that piloted civil aircraft have been flying safely
for decades UAV presents distinct new challenges
in the form of different flight profiles eg low-
elevation flights and more high-dynamic maneuvers
wider required bandwidths eg for video and
different ground site characteristics such as locations
in cluttered areas and lower elevation antennas
In this paper first the evolution of radio
technologies considered in UAV wireless
communication is reviewed in literature survey and
the significant work in the area is highlighted along
with the newest challenges The reminder of this
paper is organized as follows
The promising technology NOMA and its
variants are discussed in section three In Section
four the system model and assumptions are
presented and in section five the comparative
analysis of NOMA with existing popular technology
OFDMA (OMA) is given with simulation
persormance analysis At last the work is concluded
in section five
II LITERATURE SURVEY Drones variously known as unmanned
aerial vehicles (UAVs) unmanned aerial systems
(UAS) or remotely piloted aircraft system (RPAS)
are used in several parts of the world for surveying
and aerial mapping disaster management work
monitoring crop production and infrastructure
activities besides commercial photography and
courier delivery The viability of UAV as a
multipurpose research vehiclehas driven great
RESEARCH ARTICLE OPEN ACCESS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495450|P a g e
interest since recent decades[1] The
basictechnology building blocks responsible for the
current advancesinclude airframes propulsion
systems payloadssafety or protection systems
launch and recovery dataprocessor ground control
station navigation and guidanceand autonomous
flight controllers The following briefsurvey is
focused on the area of navigation guidance
andcontrol of UAVs Various control design for
UAVs has beenproposed ranging from linear to
nonlinear synthesis timeinvariant to parameter
varying and conventional PID tointelligent control
approaches The developed controllershave been
implemented for different aerial platforms
airship(blimp) fixed-wing UAV small scale
helicopteruad-rotors and MAV Wireless
communication systems that include unmanned
aerial vehicles promise to provide cost-effective
wireless connectivity for devices without
infrastructure coverage Compared to terrestrial
communications or those based on high-altitude
platforms on-demand wireless systems with low-
altitude UAVs are in general faster to deploy more
flexibly reconfigured and likely to have better
communication channels due to the presence of
short-range line-of-sight links However the
utilization of highly mobile and energy-constrained
UAVs for wireless communications also introduces
many new challenges In India for the regulation
and safety purpose in commercial and survilence
applications the policy guideliens also introduced
as below
Table 1UAV communication Policy Guidelines for
commercial and surveillance purpose
III MIGRATION FROM 4G LTE TO 5G The fruitful deployment of UAV based
communicationsystems for 4G and beyond future
wireless networks is highlyinvolved in finding joint
solutions to challenge of ubiquitousconnectivity with
both a multitude of devices in a spectralefficient way
as well as with energy-efficient transmissionand
operation of the UAV-BS for maximized and
armonizedcoverage and capacity [2][3] It should be
noted that suitableenergy efficiency for the UAV-
assisted ommunication systemachieves paramount
importance in the overall performance ofthe system
Efficient energy consumption results in
enhancedairtime for the communication system
improving bitsJoulesfor a given energy level
Furthermore coverage and capacityof an aerial cell
are attributed to many factors such as
thetransmission power antenna gains UAV
altitude deploymentenvironment and prominently
radio access technology [4]
4G is the fourth generation of broadband
cellular network technology succeeding 3G and
besides the popular techniques in 3G4G ie
TDMAWCDMAOFDMA a new radio access
technology NOMA is also developed by researchers
to be used in communication networks due to its
capability in increasing the system capacity
Recently non-orthogonality based system designs
are developed to be used in communication
networks and have gained significant attention of
researchers Hence multiple access (MA) techniques
can now be fundamentally categorized as orthogonal
multiple access (OMA) and non-orthogonal
multiple access (NOMA) In OMA each user can
exploit orthogonalcommunication resources either
within a specific time slot frequency band or code in
order to avoid multiple access interference The
previous generations of networks have employed
OMA schemes such as frequency division multiple
access (FDMA) of first generation (1G)time
division multiple access (TDMA) of 2G code
division multiple access (CDMA) of 3G and
orthogonal frequency division multiple access
(OFDMA) of 4G
In NOMA multiple userscan utilize non-
orthogonal resources concurrently by yielding a high
spectral efficiency while allowing some degree of
multiple access interference at receivers Recently
NOMA reputations have climbedsharply as a
fundamental solution to the challenges
encompassingthe next generation wireless networks
[5][6]NOMA has been proved to exhibit improved
spectral efficiencybalanced and air access as
compared to OMAtechnologies[6] with the ability
to cater for multipledevices in the same frequency
time or code resource thusproviding efficient access
to massive connected devices Furthermore NOMA
is also instrumental in reducingthe interference by
employing orthogonal resources as inOrthogonal
Frequency Division Multiple Access
(OFDMA)[7][17] or by sharing a single beam
between multiple users forintra-cluster access and
using NOMA for inter-cluster access[18]Current
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495451|P a g e
studies have focused on provisioning Air to
Ground(A2G) communication services mainly
through placement op- timization under various
viewpoints in literature The performance of UAV
based communication systems hasalso been
addressed for the underlaid Device to Device(D2D)
deployment scenario This work assumed
interferenceraised by D2D network nodes without
considering the presenceof terrestrial BS
Additionally there have been a fewstudies
discussing the performance of NOMA for UAV
basedcommunication system[8] A NOMA enabled
fixedwingUAV deployment was proposed in [8] to
support coveragefor ground users situated outside
BS offloaded location
In general NOMA schemes can be
classified into two types power-domain
multiplexing andcode-domain multiplexing In
power-domain multiplexing different users are
allocated[7][8][9][6][5][1][10] differentpower
coefficients according to their channel conditions in
order to achieve a high systemperformance In
particular multiple usersrsquo information signals are
superimposed at the transmitterside At the receiver
side successive interference cancellation (SIC) is
applied for decoding thesignals one by one until the
desired userrsquos signal is obtained providing a good
trade-offbetween the throughput of the system and
the user fairness In code-domain multiplexing
different users are allocated different codes and
multiplexed over the same time-frequencyresources
such as multi-user shared access (MUSA) sparse
code multiple access (SCMA) and low-density
spreading (LDS) In addition to power-domain
multiplexing and codedomain multiplexing there are
other NOMA schemes such as pattern division
multiple access(PDMA) and bit division
multiplexing (BDM) Although code-domain
multiplexinghas a potential to enhance spectral
efficiency it requires a high transmission bandwidth
andis not easily applicable to the current systems
On the other hand power-domain multiplexinghas a
simple implementation as considerable changes are
not required on the existing networksAlso it does
not require additional bandwidth in order to improve
spectral efficiency Inthis paper the prime focusis on
the power-domain NOMAAlthough OMA
techniques can achieve a good system performance
even with simple receiversbecause of no mutual
interference among users in an ideal setting they
still do not have theability to address the emerging
challenges due to the increasing demands in future
networks andbeyond
The superiority of NOMA over OMA can
besummarized as follows
_ Spectral efficiency and throughput In OMA such
as in OFDMA a specific frequencyresource is
assigned to each user even it experiences a good or
bad channel conditionthus the overall system suffers
from low spectral efficiency and throughput In
contrary inNOMA the same frequency resource is
assigned to multiple mobile users with good and
bad channel conditions at the same time Hence the
resource assigned for the weak user isalso used by
the strong user and the interference can be mitigated
through SIC processesat usersrsquo receivers Therefore
the probability of having improved spectral
efficiency and ahigh throughput will be considerably
increased
_ User fairness low latency and massive
connectivity In OMA for example in OFDMAwith
scheduling the user with a good channel condition
has a higher priority to be servedwhile the user with
a bad channel condition has to wait to access which
leads to a fairnessproblem and high latency This
approach cannot support massive connectivity
HoweverNOMA can serve multiple users with
different channel conditions simultaneously
thereforeit can provide improved user fairness lower
latency and higher massive connectivity
_ Compatibility NOMA is also compatible
with the current and future communication
systemssince it does not require significant
modifications on the existing architecture For
exampleNOMA has been included in third
generation partnership project long-term
evolutionadvanced (3GPP LTE Release 13)
Figure 1Pictorial comparison of NOMA Vs OMA
Although NOMA has many features that
may support next generationsit has some limitations
that should be addressed in order to exploit its full
advantage set Thoselimitations can be pointed out
as follows In NOMA since each user requires to
decode thesignals of some users before decoding its
own signal the receiver computational
complexitywill be increased when compared to
OMA leading to a longer delay Moreover
informationof channel gains of all users should be
fed back to the base station (BS) but this results in
asignificant channel state information (CSI)
feedback overhead Furthermore if any errors
occurduring SIC processes at any user then the error
probability of successive decoding will beincreased
As a result the number of users should be reduced to
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495452|P a g e
avoid such error propagationAnother reason for
restricting the number of users is that considerable
channel gain differencesamong users with different
channel conditions are needed to have a better
network performance
IV NOMA UPLINK AND DOWNLINK
SCENERIO SIMULATION ANALYSIS In this section an overview of NOMA in
downlink and uplink networks is introduced
throughsignal-to-interference-and-noise ratio (SINR)
and sum rate analyses Then high signal-to-
noiseratio (SNR) analysis has been conducted in
order to compare the performances of OMA
andNOMA techniques[10]
A Downlink NOMA Network
At the transmitter side of downlink NOMA
network as shown in Fig 2 the BS transmits
thecombined signal which is a superposition of the
desired signals of multiple users with different
allocated power coefficients to all mobile users At
the receiver of each user SIC process isassumed to
be performed successively until userrsquos signal is
recovered Power coefficients ofusers are allocated
according to their channel conditions in an inversely
proportional mannerThe user with a bad channel
condition is allocated higher transmission power
than the one which has a good channel condition
Thus since the user with the highest transmission
power considers the signals of other users as noise
and recovers its signal immediately without
performing anySIC process However other users
need to perform SIC processes In SIC each userrsquos
receiverfirst detects the signals that are stronger than
its own desired signal Next those signals
aresubtracted from the received signal and this
process continues until the related userrsquos own signal
is determined Finally each user decodes its own
signal by treating other users with lower
powercoefficients as noise The transmitted signal at
the BS can be written as
s = aiPsxi
L
i=1
where xi is the information of user i (Ui)
with unit energy Ps is the transmission power atthe
BS and ai is the power coefficient allocated for user
i subjected to ai = 1Li=1 and a1gea2gehellip geaL since
without loss of generality the channel gains are
assumed to be ordered as h1 2 le h2 2 le⋯ hL 2 where hL is the channel coefficient of Lth
user based on NOMAconcept The received signal
at lth user can be expressed as follows
y1 = hls + nl = hl aiPsxi + nlL
i=1
where nlis zero mean complex additive Gaussian
noise with a variance of σ2
(1) SINR analysis By using (2) the instantaneous
SINR of the lth user to detect the jth user jle l
with jne L can be written as
SINRl = alγ hl 2
γ hl 2 aiLi=l+1 + 1
Where γ = Psσ2 denotes the SNR
(2) Sum rate analysis After finding the SINR
expressions of downlink NOMA the sumrate
analysis can easily be done The downlink
NOMA achievable data rate of lth user can
beexpressed as
RlNOMA-d
= log2 1 + SINRl = log2(1 +alγhl2γhl2 i=l+1Lai+1
B Uplink NOMA Network
In uplink NOMA network as depicted in
Fig 3 each mobile user transmits its signal to the
BS At the BS SIC iterations are carried out in order
to detect the signals of mobile users By assuming
that downlink and uplink channels are reciprocal and
the BS transmits power allocation coefficients to
mobile users the received signal at the BS for
synchronous uplink NOMA can be expressed as
r = hi aiPxi + n
L
i=1
where hi is the channel coefficient of the ith
user Pxi is the maximum transmission power
assumed to be common for all users and n is zero
mean complex additive Gaussian noise with a
variance of σ2
Figure 2Downlink NOMA network
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495453|P a g e
Figure 3 Uplink NOMA network
1) SINR analysis The BS decodes the signals of
users orderly according to power coefficientsof
users and then the SINR for lth user l ne 1 can
be given by
SINRl =alγ hl 2
γ ai hi 2 + 1lminus1i=1
where γ =P
σ2
2) Sum rate analysis The sum rate of uplink
NOMA when γ minus infincan be written as
Rsum NOMA-u asymp log2(γ hl 2L
l=1
C Comparing NOMA and OMA
The achievable data rate of the lth user of OMA for
both uplink and downlink can be expressed
RsumOMA = αl log2(1 +
βlγ hl 2
αl)L
l=1
For the sake of simplicity sum rates of
uplink NOMA and OMA can be compared for
twousers Then using both the sum rate of uplink
NOMA and OMA at high SNR can beexpressed
respectively as
RsumNOMAasymp log2 γ h1 2 + γ h2 2
Here we notice ROMA
sumle RNOMA
sum
Fig shows that NOMA outperforms OMA in terms
of sum rate in both downlink and uplinkof two
user networks
V SIMULATION RESULTS
The Comparative analysis of modelling
Downlink and Uplink NOMA in comparison with
OMA is simulated and findings are presented that
shows superiority of NOMA over OMA with better
spectral efficiency for simulation parameters taken
as power allocation coefficients a1=06 a2=04 and
channel responses h1 2
=0 DB h22=20 DB
parameters
Figure 4NOMA UPLINK
Figure 5 NOMA DOWNLINK
VI CONCLUSION This paper investigated an account of
NOMArsquos applicability for UAV-assisted
communication systems NOMA schemes are
proposed to improve the efficient usage of limited
network sources OMA based approaches that use
time frequency or code domain in an orthogonal
manner cannot effectively utilize radio resources
limiting the number of users that can be served
simultaneously In order to overcome such
drawbacks and to increase the multiple access
efficiency NOMA technique has been recently
proposed Accordingly users are separated in the
power domain Such a power domain based multiple
access scheme provides effective throughput
improvements depending on the channel conditions
The crucial need of UAV communication of
optimum utilization of available licensed spectrum
bandwidth is considered here and simulation results
taken presented that NOMA performs better than
OMA while fulfilling individual user-rate constraint
for both users The research work can be further
carried out investigating joint power and phase
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495454|P a g e
allocation of UAV nodes deployment for efficient
operations
REFERENCES [1] S M I C Y L M I Muhammad Farhan Sohail
Non-Orthogonal Multiple Access for Unmanned
Aerial Vehicle Assisted Communication in IEEE
access 2018
[2] M Mozaffari Drone small cells in the clouds
Design deployment and performance analysis in
IEEE Global Communications Conference 2015
[3] R Z a T J L Y Zeng Wireless
communications with unmanned aerial vehicles
opportunities and challenges in IEEE
communication magazine 2016
[4] I B-Y a H Yanikomeroglu The new frontier in
ran heterogeneity Multi-tier drone-cells IEEE
Communications Magazine pp 48-55 2016
[5] P K S a D I Kim Uav-enabled downlink
wireless system with NOMA access in IEEE
Globecom Workshops Dec 2017
[6] P Xu and K Cumanan Optimal power allocation
scheme for nonorthogonal multiple access with
fairness in IEEE Journal on Selected Areas in
Communications oct 2017
[7] E H a D I K S Ali Non-orthogonal multiple
access (noma) for downlink multiuser mimo
systems User clustering beamforming and power
allocation in IEEE Access 2017
[8] W S M B a M D M Mozaffari Unmanned
aerial vehicle with underlaid device-to-device
communications Performance tradeoffs in IEEE
Transactions on Wireless Communications June
2016
[9] Z D X D a R Z Z Chen An optimization
perspective of the superiority of noma compared to
conventional oma in IEEE Transactions on
Signal Processing Oct 2017
[10] M T Mahmoud Aldababsa1 and S G G K 2 A
Tutorial on Non-Orthogonal Multiple Access
2017
[11] X L Z J W a K J R L Zhu Han Delay
Sensitive Scheduling Schemes for Heterogeneous
QoS over Wireless Networks IEEE
TRANSACTIONS ON WIRELESS
COMMUNICATIONS VOL 6 NO 2
FEBRUARY 2007 vol 6 no 2 2007
[12] Z J W a K J R L Z Han A resource
allocation framework with credit system and user
autonomy over heterogeneous wireless networks
in IEEE Global Telecommunications Conference
2003
[13] N B S a P S S Chen Heterogeneous delay
tolerant task scheduling and energy management in
the smart grid with renewable energy IEEE
Journal of Selected Areas in Communications vol
31 no 07 pp 1258-1267 july 2013
[14] H L Z C a Z H Y Hu Scheduling strategy for
multimedia IEEE Transactions on Vehicular
Technology July 2016
[15] P F a K B L Y Dong High-speed railway
wireless communications efficiency vs fairness
IEEE Transactions on Vehicular Technology vol
63 no 2 pp 925-930 march 2014
[16] T R a Z H Z Chang Queueing game for
spectrum access in cognitive radio networks
IEEE Communications Letters vol 19 no 11 pp
2017-2020 June 2015
[17] Z C L T R a Z H F I Yun Hu Service
Provisioning and User Association for
Heterogeneous Wireless Railway Networks IEEE
Transactions on Communications 2017
[18] H S W Tianti Chen Optimal Scheduling for
Wireless On-Demand Data Packet Delivery to
High-Speed Trains IEEE Transactions on
Vehicular Technology vol 64 no 9 pp 4101 -
4112 september 2015
Pankaj Patel Migration from 4g LTE to Advanced PHY Techniques for Unmanned Aerial
Vehicle Communication International Journal of Engineering Research and Applications
(IJERA) Vol 09 No04 2019 pp 49-54
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Improving Of Physical Layer Insecurity Of The
Non Orthogonal Multiple Access System
Pankaj M Patel Prof Dr Chetan B Bhatt
Abstract The key aspect of the NOMA (power domain non orthogonal) is the user possibility for decoding the messages belonging to another pair users
on similar resources The method interprets a security threat especially in the case where the base station serves the users with various security
clearance or untrusted users The main aspect of NOMA is to serve the multiple users upon the similar radio resources at the minimal inter user
interference expense The system not only permits the serving of particular users with high efficient bandwidth but also permits the scheduling more type
of users than the timely available users In this study we investigated the secrecy outage probability (SOP) and OP in the both two user and multi user
NOMA system where the BS is supposed to pair a trusted or legitimate user with other untrusted users because of the un even distribution of the
untrusted and trusted users in the cell SIC the successive interference cancellation was then implemented at the receiver side for decoding the
message signals With the application of NOMA concept the study investigated the pair outage behavior under the SOP constraints on the trusted users
In specific the SOP and OP of the concerned U1 were obtained in the closed type of expressions The study also provided the understanding the
possibility of obtaining an optimal outage efficiency for pairing under the SOP constraints With certain numerical simulations the study verified the
effectiveness of the analytical derivations with respect to various scenarios
Index Terms NOMA Secrecy outage Probability Successive Interference Cancellation bandwidth channel state information etc
mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash
1 INTRODUCTION The physical layer security and non-orthogonal multiple
access was regarded as the encouraging techniques for the
processing of wireless communication network systems Today
the combination of the two significant communication methods
was studied to guarantee a spectral efficient and secure
wireless transmission Most of the prevailing works
predominantly concentrated on the optimization and efficiency
of the PLS in the existence of untrusted relay nodes and
external eavesdroppers(Arafa et al 2019a)But there occurs a
gap in the theoretical studies to describe the ease of obtaining
the enhanced efficiency in the existence of untrusted users
Recently the network traffic amount have greatly enhanced
particularly with the updated growth in IoT applications in
future To rectify the huge traffic demand upcoming wireless
networks must deliver a best spectral effectiveness and large
connectivity (Sun et al 2018) NOMA is regarded as the best
technology in which various NOMA technique exhibit similar
concept of providing several users at the similar frequency and
time The famous NOMA types are code domain and power
domain that provided enhanced efficiency when compared
with the existing techniques The paper adopted the power
domain on the basis of super position coding (transmitter side)
at the SIC (receiver side) Hence the users could possess the
key for the messages of other users and thereby utilize SIC for
removing the interference (Cao et al 2019) (Zhao et al
2018) Hence various NOMA methods was proposed for
allowing the adjacent users to perform as a relay for improving
the efficiency of the weak users through the resending of
decoded data in a next time slot The weak user could utilize
the MRC technique to integrate the information achieved in
different time slots In addition obtaining a secured
communication is a crucial problem over the vulnerable
wireless networks to security threats mainly because of the
broadcasted transmission nature
The study investigated the secrecy performance and outage
with the untrusted user(Furqan et al 2019) The main aspect
of the study is to analyze the feasibility of achieving the OP of
the pair under a trusted user Because of the decoding facility
and spectrum sharing of SIC the untrusted user could perform
as a eavesdropper
Figure 1 Representation of Base station
Figure 1 depicts the representation of base station The main
aim of the proposed system defined as
bull To investigate the outage probability of the proposed
system
bull To investigate the SOP of the proposed system
bull To derive the accurate expression of the outage
probability for all kind of scenarios and closed form of
expressions for few special cases and verifying them
numerically for yielding a better outage efficiency
2 RELATED WORKS This section describes the different existing techniques and
methods related as our proposed system (Cao et al
2019)suggested two kinds of relay selection process denoted
as AF (amplify and forward) and DF (decode and forward) on
the basis of AORS and DORS for achieving secure and
reliable NOMA systems under the untrusted users The study
derived the accurate and asymptotic closed form of the SOP
expressions and the PSCP obtained by the two methods and
investigated the optimized feature of the two methods The
____________________________________
bull PANKAJ M PATEL is currently pursuing PHD program in Electronics
amp Communication in Gujarat Technological University E-mail
pankajmphd24gmailcom
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complete analysis and the simulation results represented that
both the AORS and DORS characteristically outperformed the
benchmark system apart from obtaining the similar SOP and
the required PSCP at very high Signal to noise ratio (Zhang et
al 2018)Investigated the power allocation and joint subcarrier
issue for NOMA ndashAF two-way relay networks with restrictions
The study focused to optimize the obtainable secrecy
efficiency by designing jointly the SC task power allocation
and user pair scheduling The paper suggested a SCAS-1
technique by assuming the appropriate information about the
channel state information in the relay station followed by the
formulation of SCAS-2The secured power allocation issue is
structured as a convex programming issue and then resolved
by in-depth point techniques The results of simulation
explained that the efficiency of the suggested SSPA algorithms
with and without CJ respectively (Arafa et al
2019b)Considered a downlink system where the base station
is connecting with two appropriate users in two various
scenarios in the unsecured environments which are the
presence of the eavesdropper and untrusted relay
communication In the first process several trusted
cooperative relays is engaged for assisting with the base
station transmission and protect the corresponding signals
from the eavesdropper Several relay methods are framed and
investigated for the following process which are forward and
decode cooperative jamming and AFFor all the technique
secured beam forming signals were formulated at the relays
for maximizing the obtainable secret rate areas For the next
process with untrusted relay the obtained secrecy rate areas
obtained for two various relay schemes which are AF and CF
under two various operation modes In the first process the
prescribed users will receive the signals from the untrusted
relay and the base station for decoding the messages The
study depicted that the efficient relay scheme is highly
dependent on the parameters of the system especially the
nodal distance and the secrecy rate area (Sun et al
2018)Studied the algorithm for resource allocation for MISO
systems where the full duplex BS serve several half duplex
downlink and uplink users on the similar subcarrier The
allocation of the resource have been optimized for maximizing
the weight system output whereas the leakage of information
was restricted and an artificial noise was induced for granting
secured communication with respect to potential
eavesdroppers The study formulated a novel non-convex
optimization issue by considering the imperfect CSI of the
channels and requirements of QoS of legitimate users The
simulation results stated the efficiency of the optimal algorithm
was related to the suboptimal algorithm Apart from that the
suggested MISO NOMA technique not only guarantee uplink
and downlink communication purpose for security but delivers
a characteristic rate of system secrecy when compared with
the conventional MISO and other two baseline methods
(Dang et al 2017)Analysed the outage efficiency of various
multicarrier relay selection techniques for 2 hop OFDM system
in Poisson relay fields The study concentrated on DF relay
systems with more selection schemes The accurate
expressions for the OP are provided in integrals generally
Apart from that asymptomatic derivatives for OP in the SNR
region in the fixed circle area are predicted for both relay
selection techniques in closed forms Consequently several
significant factors that are linked to the cooperative network
were examined comprising OP ratio of two selection
techniques diversity and subcarrier optimization output In
conclusion a structure to analyze the OP of OFDM with
spatially random relay have been constructed that could be
easily altered for analyzing same case with various forwarding
protocols channel conditions and location distributors (Dang
et al 2018)Proposed a full duplex OFDM ndashD2D system in two
hop network where DF relays help the transmission from DUE
transmitter to DUE receiver The study also investigated the
OP issue by integrating the transmit power within the DUE
relays and transmitter and to deliver a suboptimal solution that
can improve the outage performance The investigations are
validated by Monte Carlo simulations These results described
could furnish an insight into full duplex OFDM system and
guides for the application in the next generation network
(Kokshoorn et al 2016) suggested a robust channel algorithm
for mmWave systems on the basis of novel overlapped pattern
design With the use of finite measurements the study
depicted that this decreased measurements was found ENR of
25 dB to obtain the similar PEEFor the appropriate channel
with quickly altering channel information the price might be
acceptable for improving the speed of estimation The study
also proposed a robust channel estimation algorithm where
the additional calculations are carried out when expecting
more estimation error The study depicted that the channel
could be measured more effectively resulting in noteworthy
gains upto 6 dB when comparing with the existing algorithm
(Ali et al 2016) described the variations in the principles of
downlink and uplink NOMA transmissions in a wireless
system The study formulated a maximization issue in a cell
like the user clustering and power allocations Because of the
integral nature of the formulated programming issue the study
solved the issue in to steps which are grouping of users into
clusters and then to optimize the corresponding power
allocations The study proposed a sub optimal scheme that
exploited the gain variations in NOMA groups and clusters into
multiple and single clusters for enhancing the sum-throughput
The results compared the efficiency of OMA and NOMA in
different network scenarios (Lv et al 2017) investigated a
MCR-NOMA where the multicast user functions as relays to
enhance the efficiency of both secondary and primary
networks On the basis of the available CSI three various
secondary user schedule techniques for processing MCR-
NOMA were depicted For evaluating the system efficiency the
study derived the closed form of expressions of OP and order
of diversity for both the networks It has been described that
more spatial temporal diversity could be obtained by using the
CSI for scheduling of the secondary user (Liu et al 2016)
considered a MIMO ndashNOMA scenario for investigating a
dynamic clustering issue in an logical perspective To resolve
the problem of optimization issue three algorithms named top
down A and B bottom up were suggested for realizing various
complexity tradeoff and worst user throughput The study
noted that the top down B algorithm could obtain a better
tradeoff between throughput and complexity amongst the
applied procedures (Fianu and Davis 2018) investigated
three various rules of allocation and demonstrated the optimal
policy as an available inventory function The study also
provided the country level estimation of requirements that are
not met and the determination of the probability distribution
linked with the total undeserved counties The study have
been done for depicting the policy of allocation with respect to
effectiveness and equity (Hou et al 2018) studied the socio
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graphical impact on the mobile video services and thereby
suggested a CTMDP on the basis of resource allocation
technique by considering social graphs as the constraints
With the use of relative value an optimized policy could be
achieved that aimed at increasing the reward regarding the
average system The simulation depicted that the suggested
CTMDP obtained an increased efficiency against the state of
art methods
3 PROPOSED WORK
Fig 2 Proposed flow depicting the overall mechanism
The proposed(Interference mitigation using POMDP) overall flow
is depicted in the figure 2 After setting up of the base station the
distance between the base station and the user was determined
and if the distance is less than 200 meters it is decided as trusted
users and if it is greater than 200 m it is defined as untrusted
users In case of untrusted users the channel state information is
subjected to POMDP (Partially observable Markov Decision
Process) followed by resource allocation The performance
analysis have been done after the system The work considered
a NOMA oriented cellular setup provided with a base station at
the centre and two users as shown in the figure 2 The adjacent
(near) user possess high level of security clearance that is
required for securing with physical layer from the low
securityuntrusted clearance user (U2) that is located at a faraway
distance from the base station P is defined as the maximum
transmit power level (base station)In this paper it is assumed that
all the network nodes are installed with single antenna and further
all the channels are considered to be identical independently
quasi static with Rayleigh distribution with respect to distribution
119862119873(0 120575 frasl
120596 frasl
) In which 120575 is the distance in-between the BS
and nodes 119880 Here path-loss exponent and path-loss constant is
represented as 120572 and 120596 In addition it is assumed that base
station predicted the user location so that a better CSI is
obtainable at base station that is involved in pairing the users
The base station transmits the superimposed mixture
119909 = radic119905 119904 + radic1 minus 119905 119904
In which 119904 119904 are the unit power signals received by users 119880 and
119880 respectively 119905 is the power
allocation coefficient for the adjacent user
119903 = ℎ 119909 radic119875 + 119899
119903 = ℎ 119909 radic119875 + 119899
where ℎ ℎ - the channel gain linked with the
small-scale fading from the base station to users 119880 and 119880
respectively 119899 and 119899 are the extra white Gaussian noise with
variance and zero mean 1198730 and it is assumed that 120588 = 1198751198730 is
the BS convey signal-to-noise ratio (SNR) In NOMA technique
farther user that possess more power
could decode its own signal by considering the adjacent signal as
a noise without decoding the adjacent user message In the
preceding equation it is assumed that U1 first decode the weak
signal followed by decoding its own signal with SICU2 which is
the untrusted user attempted to decode the near user message
after the decoding of the adjacent user messages after the
process of decoding its own message with SICHence the
following equation have been achieved
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119879119900119905119886119897 = 119878119868119873119877 119878119868119873119877
119878119868119873119877 119878119868119873119877
+
where 119878119868119873119877 represented the signal-to-interference-plus-noise-
ratio of user 119898 that was decoded by 119880 for 119898119899120598119894 2+ and the
channels gain of 119880 denoted by |ℎ |
followed an exponential distribution
with the parameter 120577 = 120596 120575
Problem Formulation
Hence the base station should achieve and serve a better
communication for the users who are susceptible to security
threat from untrusted user the proposed system defined two
kinds of QoS efficiency measures that could be regarded to be
important for framing the issue In specific the study defined a pair
of OP to check the reliability of the QoS satisfaction In general
the pair OP is stated as the probability in which the obtainable
data rates dor the users equal to or greater than the least target
threshold The next metric also called as the SOP is the
probability that the non negative secrecy capacity obtained by the
trusted user is more than the threshold value
The following issue aimed at reducing the pair OP subjected to a
SOP factor for the user U1 that is provided by
min
119875
0 lt 119905 lt 05
119878119874119875 le 120573
in which 119875 119878119874119875 and 120573 are the pair OP SOP(119880 ) and the
permissible SOP threshold
4 PERFORMANCE ANALYSIS
Derivation of the Pair OP
With the use of Shannonrsquos capacity formula and considering
119862 and 119862
as the threshold capacities of users 119880 and
user 119880 respectively the OP of the pair could be provided
by
119875 = 1 minus 119876 119909119876
in which
120591 = 2
119898 120598 119894 2+
120601 =
( )
120601 =
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119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 1 120601 gt 120601
For having 120601 gt 120601 the constraint on
the power allocation factor (t) needs to be satisfied
(119905 gt
) and for this case 119876 could be obtained as
follows
119876 = exp (
)
lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 2 120601 lt 120601
Like case 1 it was stated that opposite constraint on
a as (119905 lt
) and
119876 can be derived as follows
119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
The OP of the NOMA pair
119875 = 1 minus 119891(119905)119896 (119905)
lt 119905 lt
1 minus 119891(119905)119896 (119905) 0 lt 119905 lt
in which
119891(119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
Derivation of SOP of 119880
With Shannonrsquos capacity formula the secrecy rate of
user 119880 was provided by
119878119862 = 119869 minus 119869
119869 = log (1 + 119879119900119905119886119897 (r (1)))
119869 = log (1 + 119879119900119905119886119897 (r (2)))
119878119862 is the non-negative secrecy capacity of 119880 Provided the
secrecy capacity in the SOP of 119880 is
119878119874119875 = 1 minus 120584119890
119860 =
120584 =
119879 - the user 119880 secrecy target rate
Theorem 1
Outage-optimal power allocation factor
119905 = radic
( )
In which 119908 =
119908 =
119911 = 1 + 120591
The minimum power allocation factor (119886 )
119905 =
(
)
The optimal OP of the NOMA pair under the SOP constraint
=
( )
( ( ))119890
( )
That is lt 0whih meant that the U1 (SOP) is a reducing function
Of t that results in the optimal power allocation factor that is
greater than 119905 for the satisfaction of secrecy constraining
factorPartially observable Markov decision process S is
represented as statesLet D is the channel features which is
consider here as actions the conditional transition probability
between states is regarded as T Reward function R is
calculated as the prediction of maximum capacity channel with
respect to data rate r = R(S x D) the agent receives an
observation o ϵ 120118 o isin Ω display style oin Omega that
depended on the new environment state S and on the just
took action d with the probability O(o|s d)
Reward received at time t is conveyed as r = R(S x D)
H is the belief states over POMDP states
119867 is the belief state transition function
119903 = 119877(119867 x 119863) is the reward function on the belief states
119861 (ℎ 119889 ℎ ) = sum Pr ( 120118 ℎ |ℎ 119889 119900) Pr(119900|119889 ℎ)
Pr(h |h d o) =
1 if the belief update with arguments h d o returns h 0 otherwise
The reward function is updated on the basis of the belief MDP
r (h d) = sum h(s) R(s d) isin
the agent focus on the largest expected immediate rewardin
other words the maximum capacity channel The section
analyse the accuracy of the analytical derivations under
various settings
Figure 3 The feasible pairing
The SOP of U1 with the increasing untrusted user U2 and
distance (d2) for several BS transmits Signal to Noise Ratio
at 120588 = minus20minus1020 119889119861is depicted in with a=005 and 01 and
d1=200m is depicted in the figure The results stated that the
U1(SOP) is a gradually reducing function as per d2 that
implies that the increasing value of d2 leads to the
improvement of the SOP of U1 Since the provided constant
threshold ϵ in SOP restraint U2must be situated at a larger
space when compared with threshold value to obtain the SOP
of U1 Apart from that it is normal that the high the target
secrecy rate rises the SOP of U1
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Figure 4 The Secrecy outage probability
Feasible Pairing in th SOP of pair OP and U1 with the
enhanced power allocation factor (a) in which d2 = 700 m d1
= 200 m 120588 = 15 dB and ϵ = 01 The results depicted that the
the pair OP and SOP of user U1 with increased a for two (d2)
various distances of the (U2) untrusted user The results
approve the convex nature of the pair OP and the SOP curve
is gradually decreasing on the basis of a Generally during the
increase in a the power assigned to the weak user message
decreases that minimize the ability of U2 for discriminating the
superior positioned signals thereby improving the SOP of U1
Figure 5 The Pair outage probability
Pair OP in case of rising U2 untrusted user in distance (d2)
for different base station transfer the signal to noise ratio(120588 =
5 15 25 dB) where a = 015 and d1 = 200 m
Figure 6The infeasible pairing of secrecy outage
probability of the pair OP and U1
The infeasible pairing of SOP (U1) and the pair outage
probability with the enhanced allocation of the power ad1(200
m)d2(300 m)120588 = 15dB and ϵ = 0
The figure 6 depicted that the
The figure 6 shows the similar plotting of the data by altering
the untrusted user location by transferring it to a BS closer
distance (d2 = 300 m) It also depicted that the U1 SOP
constraint of is disrupted at a because the SOP is more than ϵ
The accuracy is well-matched and verified with all range of
numerical simulation The results noticed that the efficiency is
based on the comparative locations of the two user with the
base station
Figure 7 The figure 7 depicts that SNR versus strictly
positive secrecy rate
The observed graph proves that the secrecy capacity
outperforms the existing techniques The proposed precoding
application increases the performance of the system The
transmission power of the system is the power required to
transmit a particular data When there is an increase in the
number of users there is the possibility of inference in the data
transmission and hence the efficiency of the data rate may be
affected Depending on these instances the efficiency of the
antenna capacity to withheld and accommodate the data
determined
Figure 8 The power radiated by BS antenna
In the figure 8with respect to the simulation setup the
precoding methods are performed based on the radiated
power per BS antenna is depicted The results observed the
better efficiency of the proposed system The proposed proves
to be better when compared with existing linear precoding
methods in the prescribed three metrics thereby stating that
MRT may be utilized for the the examination of the secrecy
capacity Our proposed technique spends less radiatated
power thereby increasing the overall capacity of the system
5 CONCLUSION The NOMA system decodes the messages of other user pairs
on the similar resources thereby promoting user possibility
The technique interprests a security threat in which the BS
serves the untrusted users The study analysed the SOP and
OP in both multi user and two user NOMA system in which the
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base station pairs the trusted user in closed type of
expressions The proposed (Interference mitigation using
POMDP) also enable the understanding of possibility of
achieving outage optimal efficiency to pair under SOP
constraints The numerical verifications verified the efficiency
of the analytical derivations
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Dynamic user clustering and power allocation for
uplink and downlink non-orthogonal multiple access
(NOMA) systems IEEE access 4 6325-6343
[2] ARAFA A SHIN W VAEZI M amp POOR H V
2019a Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
15 210-222
[3] ARAFA A SHIN W VAEZI M amp POOR H V
2019b Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
[4] CAO K WANG B DING H LI T amp GONG F
2019 Optimal Relay Selection for Secure NOMA
Systems under Untrusted Users IEEE Transactions
on Vehicular Technology
[5] DANG S CHEN G amp COON J P 2018
Multicarrier relay selection for full-duplex relay-
assisted OFDM D2D systems IEEE Transactions on
Vehicular Technology 67 7204-7218
[6] DANG S COON J P amp CHEN G 2017 Outage
performance of two-hop OFDM systems with
spatially random decode-and-forward relays IEEE
Access 5 27514-27524
[7] FIANU S amp DAVIS L B 2018 A Markov decision
process model for equitable distribution of supplies
under uncertainty European Journal of Operational
Research 264 1101-1115
[8] FURQAN H M HAMAMREH J amp ARSLAN H
2019 Physical Layer Security for NOMA
Requirements Merits Challenges and
Recommendations arXiv preprint arXiv190505064
[9] HOU L ZHENG K CHATZIMISIOS P amp FENG Y
2018 A Continuous-Time Markov decision process-
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for mobile video services Computer
Communications 118 140-147
[10] KOKSHOORN M CHEN H WANG P LI Y amp
VUCETIC B 2016 Millimeter wave MIMO channel
estimation using overlapped beam patterns and rate
adaptation IEEE Transactions on Signal Processing
65 601-616
[11] LIU Y ELKASHLAN M DING Z amp
KARAGIANNIDIS G K 2016 Fairness of user
clustering in MIMO non-orthogonal multiple access
systems IEEE Communications Letters 20 1465-
1468
[12] LV L CHEN J NI Q amp DING Z 2017 Design of
cooperative non-orthogonal multicast cognitive
multiple access for 5G systems User scheduling and
performance analysis IEEE Transactions on
Communications 65 2641-2656
[13] SUN Y NG D W K ZHU J amp SCHOBER R
2018 Robust and secure resource allocation for full-
duplex MISO multicarrier NOMA systems IEEE
Transactions on Communications 66 4119-4137
[14] ZHANG H YANG N LONG K PAN M
KARAGIANNIDIS G K amp LEUNG V C 2018
Secure communications in NOMA system
Subcarrier assignment and power allocation IEEE
Journal on Selected Areas in Communications 36
1441-1452
[15] ZHAO T LI G ZHANG G amp ZHANG C-X
Security-Enhanced User Pairing for MISO-NOMA
Downlink Transmission 2018 IEEE Global
Communications Conference (GLOBECOM) 2018
IEEE 1-6
copyPankaj Manubhai Patel
DECLARATION
I declare that the thesis entitled lsquoHeterogeneous Wireless Network using Non-
Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo submitted
by me for the degree of Doctor of Philosophy is the record of research work carried out
by me during the period from January 2014 to November 2021 under the supervision
of Dr Chetan B Bhatt and this has not formed the basis for the award of any degree
diploma associateship fellowship titles in this or any other University or other
institution of higher learning
I further declare that the material obtained from other sources has been duly
acknowledged in the thesis I shall be solely responsible for any plagiarism or other
irregularities if noticed in the thesis
Signature of the Research Scholar Date 17092021
Name of Research Scholar Pankaj Manubhai Patel
Place Ahmedabad
CERTIFICATE
I certify that the work incorporated in the thesis lsquoHeterogeneous Wireless Network
using Non-Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo
was submitted by Shri Pankaj Manubhai Patel was carried out by the candidate under
my supervisionguidance To the best of my knowledge (i) the candidate has not
submitted the same research work to any other institution for any degreediploma
Associateship Fellowship or other similar titles (ii) the thesis submitted is a record of
original research work done by the Research Scholar during the period of study under
my supervision and (iii) the thesis represents independent research work on the part of
the Research Scholar
Signature of Supervisor Date 17092021
Name of Supervisor Dr Chetan B Bhatt
Place Ahmedabad
Coursework Completion Certificate
This is to certify that Mr Pankaj Manubhai Patel enrolment No 139997111012 is a
PhD scholar enrolled in the PhD program in the branch Electronics and
communication Engineering of Gujarat Technological University Ahmedabad
(Please tick the relevant option(s))
HeShe has been exempted from the coursework (successfully completed during
the MPhil Course)
HeShe has been exempted from Research Methodology Course only
(successfully completed during the MPhil Course)
HeShe has successfully completed the PhD coursework for the partial
requirement for the award of PhD Degree His Her performance in the
coursework is as follows
Grade Obtained in Research Methodology
(PH001)
Grade Obtained in Self Study Course
(Core Subject)
(PH002)
BC BB
Supervisorrsquos Sign
Name of supervisor Dr Chetan B Bhat
Originality Report Certificate
It is certified that PhD Thesis titled lsquoHeterogeneous Wireless Network using Non-
Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo by Shri
Pankaj Manubhai Patel has been examined by us We undertake the following
a The thesis has significant new workknowledge as compared to already
published or is under consideration to be published elsewhere No sentence
equation diagram table paragraph or section has been copied verbatim from
previous work unless it is placed under quotation marks and duly referenced
b The work presented is original and the own work of the author (ie There is no
plagiarism) No ideas processes results or words of others have been presented
as the Authors own work
c There is no fabrication of data or results which have been compiledanalyzed
d There is no falsification by manipulating research materials equipment or
processes or changing or omitting data or results such that the research is not
accurately represented in the research record
e The thesis has been checked using (copy of originality report attached) and found
within the limits as per GTU Plagiarism Policy and instructions issued from time
to time (ie Permitted similarity index lt=25)
Signature of the Research Scholar Date 17092021
Name of Research Scholar Pankaj Manubhai Patel
Place Ahmedabad
Signature of Supervisor Date 17092021
Name of Supervisor Dr Chetan B Bhatt
Place Ahmedabad
132
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Submitted 2021-09-22 091500
Submitted by
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Submitted by ap_rgandhigtueduin
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URL httpsarxivorgpdf190208992
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Fetched 2020-11-03 060445
1
SODH PAPER FOR PLAGRIASMdocxDocument SODH PAPER FOR PLAGRIASMdocx (D47816804)
1
PhD THESIS Non-Exclusive License to
GUJARAT TECHNOLOGICAL UNIVERSITY
In consideration of being a PhD Research Scholar at GTU and in the interests of the
facilitation of research at GTU and elsewhere I Pankaj Manubhai Patel has Enrollment
No139997111012 hereby grants a non-exclusive royalty-free and perpetual license to
GTU on the following terms
a) GTU is permitted to archive reproduce and distribute my thesis in whole or in part
andor my abstract in whole or in part (referred to collectively as the ldquoWorkrdquo) anywhere
in the world for non-commercial purposes in all forms of media
b) GTU is permitted to authorize sub-lease sub-contract or procure any of the acts
mentioned in paragraph (a)
c) GTU is authorized to submit the Work at any National International Library under
the authority of their ldquoThesis Non-Exclusive Licenserdquo
d) The Universal Copyright Notice (copy) shall appear on all copies made under the authority
of this license e) I undertake to submit my thesis through my University to any Library
and Archives Any abstract submitted with the thesis will be considered to form part of
the thesis
f) I represent that my thesis is my original work does not infringe any rights of others
including privacy rights and that I have the right to make the grant conferred by this
nonexclusive license
g) If third party copyrighted material was included in my thesis for which under the terms
of the Copyright Act written permission from the copyright owners is required I have
obtained such permission from the copyright owners to do the acts mentioned in paragraph
(a) above for the full term of copyright protection
h) I retain copyright ownership and moral rights in my thesis and may deal with the
copyright in my thesis in any way consistent with the rights granted by me to my
university in this non-exclusive license
i) I further promise to inform any person to whom I may hereafter assign or license my
copyright in my thesis of the rights granted by me to my university in this non-exclusive
license
j) I am aware of and agree to accept the conditions and regulations of a PhD including
all policy matters related to authorship and plagiarism
Signature of the Research Scholar
Name of Research Scholar Pankaj Manubhai Patel Date 17092021
Place Ahmedabad
Signature of Supervisor
Name of Supervisor Dr Chetan B Bhatt Date 17092021
Place Ahmedabad
Seal
i
ABSTRACT
The landscape of future fifth-generation (5G) radio access networks is
expected to seamlessly and ubiquitously connect everything and
support higher traffic volumes densely connected wireless devices and
diversified requirements on reliability latency battery lifetime etc as
opposed to the current fourth-generation (4G) cellular networks
Moreover in unexpected or emergencies (such as disaster relief and
service recovery) the deployment of terrestrial infrastructures is
economically infeasible and challenging due to high operational
expenditure as well as sophisticated and volatile environments To
address such novel issues intelligent heterogeneous architecture by
leveraging unmanned aerial vehicles (UAVs) (or commonly known as
drones) has been considered to be a promising new paradigm To
improve the system performance of UAV communication in 5G
networks physical layer techniques are of much concern as they affect
the applications of UAVs significantly In this research work security
aspects of NOMA-based UAV communication network have been
considered for optimization as physical layer security in a wireless
communication network is not as robust as wired communication due to
fading and varying SNR scenarios Here primarily two usersrsquo models
as the trusted and untrusted user communicating with BS have been
optimized for outage-optimal performance considering pair Outage
probability and Secrecy outage probability as performance metrics The
achieved results are extended to multi-user scenarios also and for the
optimal policymaking dynamic programming and Partially Observable
Markov Decision Process (POMDP) optimization approaches have
ii
been simulated and verified The simulated results have shown that
POMDP has potential consideration as a resource scheduling
optimization technique in the NOMA-UAV communication network for
providing secure and more robust performance
iii
Acknowledgment
Completing a PhD is a tough task that requires hard work and a lot of effort This is
often an overwhelming but also great experience that I would not have been able to
complete without the assistance and support of so many people Thus it is my great
pleasure to thank all those people First of all I would like to thank almighty for giving
me the strength to carry out this task I would like to deeply thank Dr Chetan B Bhatt
my supervisor for his guidance encouragement and support over these years This
research work would not have been possible without his constructive pieces of advice his
systematic guidance and his patient support thought out the duration of my research work
I would like to express my sincere gratitude to Dr Harshal A ALOORKAR and Dr
KIRAN R TRIVEDI Dr Mehul Raval my doctoral progress committee members Their
rigorous style of reviewing and constructive feedback with valuable suggestions of Dr
Prakash Gajjar Mr Hitesh Panchal and Mrs Monali Mandli who spent their valuable
time whenever required for discussing aspects of this work and provided relevant material
as well Mr Parth Modi and Mr Jagadish Patankar to initiate and inspired me a lot to
continue my work Mr Mukesh Sharma who help in maintain documents I am also
thankful to my parents and family members who always stood with me in each critical
situation and supported me endlessly I am thankful to all EC departments of various
polytechnic and degree engineer colleges for their cooperation in every possible means
Lastly I would thank all the people who directly or indirectly helped me during this very
important phase of my life
Pankaj Manubhai Patel
vi
List of Abbreviation
3GPP 3rd Generation Partnership Project
5G Fifth Generation
A2G Air to Ground
AWGN Additive White Gaussian Noise
BDM Bit Division Multiplexing
BS Base Station
BPCU Bits Per Channel Use
CDMA Code Division Multiple Access
CR Cognitive Radio
CSI Channel State Information
CNPC Control and Non-Payload Communications
CRN Cognitive Radio Networks
D2D Device-to-Device
DCP Difference of Concave Programing
DOMP Dynamic Optimization Method of Programming
FR Floating Relay
GSM Global System for Mobile Communications
HLPSL High-Level Protocol Specification Language
ICT Information and Communication Technology
IoT Internet of Things
IRS Intelligent Reflecting Surface
IMT Information Management Technology
vi
LDS Low-Density Spreading
LTE Long Term Evolution
LTE-A Long Term Evolution Advance
MCR Multicast Cognitive Radio
MI Mobile Internet
MIMO Massive Multiple-Input Multiple-Output
mm-Wave millimeter Wave
MTC Machine-Type Communication
MUSA Multi-User Mutual Access
NOMA Non-Orthogonal Multiple Access
OFDMA Orthogonal Frequency Division Multiple Access
OMA Orthogonal Multiple Access
OP Outage Probability
POMDP Partially Observable Markov Decision Process
PLS Physical Layer Security
PDMA Pattern Division Multiplexing Control
PUN Primary User Networks
QoS Quality of Service
RIS Reconfigurable Intelligent Surface
RNRF Random Near-Random Far
Rs Target Secrecy Rate
SAGIN Space-Air-Ground Integrated Networks
SIC Successive Interference Cancellation
STBC Space-Time Block Coding
vi
SBF Secrecy Beam Forming
SCMA Sparse Code Multiple Access
SOP Secrecy Outage Probability
TAS Transmit Antenna Selection
TDMA Time Division Multiple Access
UAVC Unmanned Aerial Vehicle Communication
UMTS Universal Mobile Telecommunication Systems
URLLC Ultra-Reliable Low Latency Communication
vii
List of Figures
Figure Title Page
No
11 Usage of wireless sensor network and UAV in the
hazardous disaster control
6
12 UAV network applications types with security services
architecture
8
13 UAV-assisted heterogeneous network architecture 12
14 Security problems in the UAV 15
15 Comparative analysis of NOMA vrsquos OMA 18
21 Vehicular communication NOMA system 28
22 RS-NOMA against an external eavesdropper 31
31 Downlink NOMA network 44
32 Uplink NOMA network 46
33 Multi-two user architecture of NOMA system 49
34 Flow Diagram of the proposed system 50
35 Near and Far User 51
41 Impact on Sop with increase distance between BS and user U2 60
42 Impact on Sop with increase distance between BS and user U2 61
43 Feasible pairing t Vs pair OP 61
44 Infeasible pairing t Vs pair OP 62
45 Secrecy outage probability 63
46 Pair outage probability 63
47 SNR versus Strictly positive secrecy rate 64
48 Power radiated by per MMBs antenna 64
viii
List of Tables
Table Title Page
No
11 Physical layer hazards and measures in UAV wireless
communication network
13
21 Comparative analysis 33
31 List of parameters59 54
41 Simulation parameters 59
ix
Table of Content
Sr
No
Title Page
No
I Abstract I
II Acknowledgment II
III List of Abbreviation III
IV List of Figures Iv
V List of tables V
1 Introduction 1
11 Modern technology and its needs 1
111 Long term evolution of 4G network 2
112 Migration from 4G LTE to 5G for UAV communication 3
12 UAV assisted communication in heterogenous sensor network 5
121 Introduction to UAV Communication network 7
122 Tyews of UAVs 8
1221 UAVs as flying BSs 8
1222 UAVs as aerial UBs 10
13 Unmanned aerial vehicle for 5G network 11
14 Physical layer insecurity in UAV communication network 12
141 Principles of security 13
15 Non-Orthogonal Multiple Access (NOMA) system secured
communication
16
151 Comparison of NOMA Vs OMA 16
1511 Spectral throughput and efficiency 17
1512 User fairness and higher lately 17
1513 Compatibility 17
16 Problem identification 18
17 Motivation 19
18 Aim and objective of the research 20
19 Thesis organization 21
2 Literature review 23
x
21 Integration of UAV Networks for 5G and B5G communication 23
22 UAV-NOMA in physical layer security enhancement 26
23 Research methodology 38
24 Summary 39
3 System model for NOMA-UAV communication 41
31 NOMA -UAV system secured communication for 5G 41
311 The basic scheme of NOMA 41
312 Downlink of NOMA 44
313 Uplink of NOMA 46
314 Comparison of NOMA and OMA 47
32 PLS performance metrics in NOMA -UAV communication 47
321 SOP and OP - two user and multi-user NOMA system 48
322 System Model 48
323 Partially Observable Markov Decision Process-POMDP 50
324 Problem formulation 52
33 Performance Analysis Improving PLS Insecurity of NOMA
System
53
331 The pair OP calculation 53
332 Pseudo-code for the proposed algorithm 55
34 Summary 57
4 Result and discussion 58
41 Performance measure of secured NOMA-UAV communication
model
58
42 Numerical result and discussion 59
421 Feasible amp Infeasible pairing of trusted amp untrusted
users
60
422 The secrecy outage probability and pair outage
probability
62
423 SNR versus strictly positive secrecy rate 63
424 Power radiated by per MMBs antenna
64
43 Conclusion and scope of future work 65
431 Conclusion 65
432 Future scope 66
xi
5 References 67
8
Publications 78
1
CHAPTER -1
INTRODUCTION
11 Modern technology and its needs
Mobile technology has undergone various generational shifts transforming the
cellular framework into a worldwide set of interconnected networks In recent days
the fifth generation (5G) has delivered voice as well as video streaming It has a
very complex range of networking services for more than nine billion users and also
billions of devices that will be connected (Hu 2016) However 5G offers a new
outlet for reflection It involves a radial network architecture for the installation of
communication-type machines 5G network can also include powerful support
applications with widely varying operating parameters 5G is a blend of network
technologies that have been developed The new 5G technology will be able to
exchange information anywhere every time for the benefit of people enterprise
and society and technical environments using a restricted access bandwidth to
carry data Now it is more than a modern series of technologies and as opposed to
previous generations would entail tremendous infrastructure or machinery
upgrades This technology aims to expand on the advances that telecommunications
systems have already achieved The projected standards of efficiency that
technologies would need to resolve are
bull Five times reduce end-end latency
bull Ten to a hundred times the higher complex rate of user data
bull Battery life is ten times longer
bull 10 to 100 times higher number of connected devices
In this research work the UAV-assisted communication over the 5G network has
been proposed with enhanced physical layer security aspects NOMA has been
proposed as the reference framework architecture for UAV communication as one
of the recent popular 5G techniques Along with the advantage of suitability in UAV
communication network NOMA has the disadvantage of insecurity in the physical
layer Here the migration of Long Term Evolution (LTE) to advanced physical layer
2
security for Unmanned Aerial Vehicle communication (UAV) over 5G network has
been proposed and also improve the insecurity of Non-Orthogonal Multiple Access
(NOMA) System We will discuss in the further chapter the proposed work This
chapter describes the introduction and basic concepts of the 5G networks with
methodology techniques and types It states the problem identification motivation
and further aim and objective of this work
111 Long Term Evolution of 4G Network
LTE is customary for 4G wireless broadband trends that provide improved network
capability and gives mobile device users speed It offers high peak data transform
rates in the range of 100 Mbps and 30 Mbps downstream and upstream
respectively It provides a capacity of scalable bandwidth mitigated latency and
backward compatibility with the previous Global System for Mobile
Communications (GSM) and Universal Mobile Telecommunication Systems
(UMTS) technology
The fourth development of cellular networks (4G) has already been developed to
meet the standards of the 3G and 2G families Every 10th year a new mobile
generation claimed to be familiarized with the first 1G system in 1981 tracked by
the 2G system that went on to roll out in 1992 and 3G launched in 2001 growth in
the year 2002 of 4G networks The actual new revolution began in December 1998
with the 3rd Generation Partnership Project (3GPP) With high-quality video and
images 3G networks are designed for multimedia networking with them Peoples
communication can also be enhanced and connectivity to public and private
network information and resources has improved with higher frequencies and new
flexible communication features third-party device applications
With the start of LTE-Advanced several vital demands and improvements are
beginning to emerge Various importance purposed for LTE-Advanced can be
exemplified as follows (Abed)
bull Provides spectrum output with LTE delivered more than three times
bull Spectrum can help scalable bandwidth and convergence of the spectrum
where it is necessary to use a non-contiguous range
3
bull Provides uplink and downlink spectrum output that varies between
15bpsHz and 30bpsHz
bull The edge throughput must be twice that of the user cell in LTE
bull From idle status to connected status the communication latency scenario is
smaller than 50msec and less than 5msec for direct packet transfer
bull Any users total throughput must be three times that of LTE
bull LTE advancement will provide 3GPP as well as LTE compatibility via inter
networking
bull The mobility conditions that are used in LTE are identical
The latest LTE advanced requirements are not yet included in device
specifications there are high-level purposes Before it is fixed in the specifications
and needs to be tested much effort remains to be approved
112 Migration from 4G LTE to 5G for UAV communication
The productive implementation of a UAV communication network in 4G and the
upcoming wireless network is included in identifying combined solutions to test
the correlation with both multitudes and also energy-efficient transmission Then
the process of the UAV-BS to optimize coverage and power It is stated that the
energy efficiency of the UAV-aided communication system is needed Efficient
energy utilization contributes to increased air time in the contact system and
increased joulesbits at a provided energy level Also aerial cell coverage and
ability may be because of various parameters such as antenna gains transmission
strength radio access technology UAV altitude and deployment environment
4G is the fourth generation of network infrastructure technologies to replace 3G and
in addition to the popular 3G4G methods Code Division Multiple Access
(CDMA) Time Division Multiple Access (TDMA) and Orthogonal Frequency
Division Multiple Access (OFDMA) Researchers are designing the latest Non-
Orthogonal Multiple Access (NOMA) technologies to be used because of their
capability to improve the performance of communication networks Non-
4
orthogonality-based device designs have recently been developed for use in
communication networks and drawn considerable interest from researchers
Henceforth Multiple Access (MA) methods can be sub-divided as OMA and
NOMA Each user may utilize orthogonal communication resources to determine
multiple access interference inside a frequency band code and time slot in OMA
Its methods such as First generation (1G)- FDMA 2G -TDMA 3G -CDMA and
4G - OFDMA have been used in previous network generations In NOMA by
producing a higher spectral efficiency however enabling some amount of multiple
entree intrusion in receivers and multiple users may use non-orthogonal resources
simultaneously Recently the credibility of NOMA as a solution to the problems of
the next generation of wireless networks has been increased Compared with OMA
technologies NOMA has been described to improve spectral quality be well-
adjusted with air connectivity and can provide accommodations for multiple
strategies at the same time of frequency Therefore enabling excellent progress to
massively correlated devices
In particular NOMA also affects mitigating interference by using OFDMA as an
orthogonal method or through offering a standard intra-cluster access beam across
multiple users and inter-cluster access in NOMA Recent studies have concentrated
primarily on the provision of Air to Ground (A2G) connectivity services through
optimization of a different point of view
The output of the UAV-based communication network was discussed in the Device
to Device (D2D) implementation setup The proposed system hypothesized
interference caused through D2D network nodes deprived of acknowledging the
occurrence of global BS Also several studies addressed the efficiency of NOMA
It permitted the deployment of fixed-wing to assist coverage in-ground user located
outer location of offloaded BS
NOMA systems are divided into two categories namely code domain and power
domain multiplexing In the power domain user accounts are allocated to different
power coefficients as per their channel complaint to reach optimal device
efficiency Multiple user signals are applied to the side of the sender Then on the
received signal Successive Interference Cancellation (SIC) is implemented to
decipher signals in sequential order until the predicted signal is achieved offering
5
a good trade-off between efficiency of the system and user fairness Different code
domain multiplexing is Sparse Code Multiple Access (SCMA) Low-Density
Spreading (LDS) and Multi-User Mutual Access (MUSA) Compared to power and
code domain multiplexing there are alternate NOMA techniques such as Bit
Division Multiplexing (BDM) and Pattern Division Multiplexing Control (PDMA)
However this multiplexing is capable of improving the efficacy of spectral It
requires a large transfer of bandwidth which is not appropriate for new methods
But on the other side the power domain has direct execution since there is no need
for significant improvements to the current networks It also does not necessitate
bandwidth to increase spectral efficiency In this chapter the main emphasis
depends on the power domain NOMA While OMA strategies can produce the best
results also with necessary receivers due to no mutual intervention among users in
an optimal situation they cannot even resolve increasing problems due to growing
demands on connectivity growth and even beyond
12 UAV assisted communication in heterogeneous sensor network
Wireless communications had created a golden chance for urban and rural
territories The LTE (Long term evolution) and LTE-A (Long term evolution
Advance) had offered the service (with QoS) for all customers through wireless
The traffic properties in the machine type communications (MTC) and the
accumulation of the MI (Mobile Internet) had made the difficulty of implementing
the cellular communication networks Installing base stations was impractical in the
urban areas due to its cost To overcome this issue the UAV suggested that it
contains the merits of compatibility and high battery life and is affordable Most of
the devices like the sensor nodes and professional cameras had been used in UAV-
assisted networks Here the UAV-assisted floating relay (FR) was launched in the
cellular communication networks UAVs were implemented more with WSN
(wireless sensor networks) The base stations were adopted with the UAV So the
MI and MTC traffic challenges were controlled (Yue Li amp Cai 2017)
UAV-assisted Heterogeneous networks had implemented in vast practical
applications UAV helped heterogeneous networks were applied in the military
department In the military the UAV had examined and surveyed the opposing
6
countryrsquos activities for security The UAV-based heterogeneous networks were
used in the military sectors where a novel authentication scheme was introduced
As The one-to-one communication via WSN was considered as secured
communication WSN had the disadvantage of consuming power The
authentication was implemented in the tool of Automated Validation
of Internet Security Protocols and Applications (AVISPA) in which the expression
had been written in the High-Level Protocol Specification Language (HLPSL)
programming language The authentication had evaluated between the user and the
base station Similarly the authentication between the user and the UAV was
calibrated The citizen and economic safety are predicted and conserved through
reliable communication in the military by obtaining foes exploration information
The faithful secured communication was confirmed using AVISPA (Rashid et al
2019)
Figure 11 Usage of wireless sensor network and UAV in the hazardous
disaster control
The integration of the wireless sensor networks and the unmanned aerial vehicle
UAV was analyzed and applied to manage the natural disaster illustrated in Figure
11 The aircraft can prevent the fire spreading drop sensors the temperature map
and biodiversity map by sensors the wildfire can easily route The wild animals can
7
be tracked and the dynamic data of moving animals can be gathered by WSNs The
biologists can fix the sensor in the animals collar the radiation that positively
affects humans can be observed in affected areas The WSNs help to prevent heart
attack of a person by monitoring heart rate The state of health can be known
through a message alarm using a GPRS system
The cooperative networks of WSN and UAV were implemented in the military
sector for the advantageous feature The UAV was providing good connections
overlapping and overall data rate The conventional UAV method aided sensor
networks concentrated only on the single tasks of monitoring accumulating
information and localization The multi-UAV had not been implemented in the
sensor networks The animal colony perception technique was utilized for
scheduling the resourced and the target assignment Functions of multi-data were
used for localization by the target recognition method (Gu Su et al 2018)
The Physical Layer Security (PLS) was achieved through 5G technologies delicate
coding for the PLS dense MIMO multi-input multi-output mm-Wave frequency
band using heterogeneous sensor networks NOMA and full-duplex mode of
communication IoT and Machine-type communications (MTC) emerged in the 5G
systems (Wu et al 2018)
121 Introduction to UAV communication network
The usage of the UAV will develop more in the next era These pre-programmed
aircraft are intended for applications in several civil settings as well as industrial
visualization agriculture rescue and search and then receiving of scientific data
These devices are called the unsuccessful inaccuracy of drones which must be
incorporated into the system of national airspace as well as worldwide The usage
of UAVs in the neutral form is always secure It has a direct inference for the control
and a payload communication system that is utilized to function effectively
Similarly surveillance and navigation operations must be made more accurate and
consistent Due to these critical factors many kinds of research in a UAV testing
development and standardization difficulties are undergone through industries
education and governments
8
Even though civil aircraft had been operating for many years yet UAV offers new
consequences in terms of various flight profiles For example high dynamic
maneuvers and low elevation flights need bandwidth video and different ground
site characteristics namely clutter locations and elevation antennas which are low
This chapter explains the core topic of the proposed work The migration of LTE
4G towards the advanced one of the physical layers for UAV communication It has
higher mobility and lower expense identified in a broad range of applications
122 Types of UAVs
The UAVs have a two-network application with security services such as UAVs as
Flying Base Stations (BSs) and UAVs as Aerial BSs in the presence of
eavesdroppers
(a) UAVs as Flying BSs (b) UAVs as Aerial mobile UEs
Figure 12 UAV network applications types with security services
architecture
1221 UAVs as flying BSs
The required infrastructure can be destroyed in natural disasters particularly
tsunamis earthquakes and snowstorms and the requisite emergency data traffic
cause both overloading and congestion of neighboring mm-Wave (Zeng et al
2016) A capable explanation is to rapidly introduce low-altitude UAVs as flying
9
BSs in such a network breakdown to improve the communication infrastructure to
mitigate cell congestion or site failure thus creating a small aerial cell
In this situation wireless communications can occur in an ad-hoc manner with
UAVs to UEs UAVs to UAVs As highlighted in Figure-12 (a) and control
stations of UAVs to ground It will increase capability dramatically and enlarge the
target of wireless networks in provisional measures as it is possible to create LoS
communication links among UAVs and UEs supported on the ground Yet form an
operating aerial cell system to monitor ground segments of UEs mobility which is
more stable to minimize sporadic connectivity on the other side
Also this can be expanded to allow several UAVs-BSs to be deployed to increase
the exposure area for supporting a wide range of UEs A network period various
UAVs-BSs is entirely independent A new paradigm was introduced through
collaboration between UAVs-BSs to extend the feasibility for a single UAV from
either a stand-alone active sensor to a wireless network over the next generation
There is a growing concern about the privacy problem in tandem with the brief
introduction of this network Wireless protection is the central issue of the
communication level wherever eavesdropping subsidizes for deliberately listening
to a source of secret information which harms the extensive placement of UAV-
BSs
A UAV-BSs is to mount several antennas in the UAV-BSs the benefits of multi-
antenna innovations geographical degree of freedom that offers an ability for UAV-
BSs to transmit eavesdropping airborne beams
Notice that in UAV systems multi-antenna technology can be technically applied
while directly modifying the separation of the antennas The existing system has
shown that transmitted beam forming models can significantly boost the
confidentiality efficiency of wiretap channels for multiple antenna transmitters
Noise may be inserted with the signal to substantially degrade the acknowledged
SINR at the eavesdroppers to prevent the information overflow
10
1222 UAVs as aerial UEs
This has already been demonstrated by reaping the benefits of Wi-Fi and LTE
technologies through field trials (Van der Bergh et al 2016) UAV-UEs typically
get their tasks for a variety of convincing IoT applications mainly in air freight
services like the google wing project Unlike conventional land base package
delivery but UAV delivery has distinctive merits such as
bull Acceleration of land transport as UAVs are not liable to road jams
bull Connection to areas that are difficult to reach
bull Decreasing the use of capital about workforce and electricity
UAV distribution is significantly dependent on having reliable and secure wireless
communication among UAVs and ground BSs especially if the UAV needs control
outside LoS the UAV-UEs are used which can develop LoS connectivity to cellular
BSs The UAV-UEs on the one hand provides high-speed access to data as it can
fly continuously in either direction On the other hand the installation of UAV-UEs
can lead to significant interference with the ground BSs in the execution of their
missions
A wide-scale installation of UAV-UEs is only feasible for this reason if the issues
of interference management are tackled It is widely known that interference
negatively affects wireless networks As highlighted in Figure-12 (b) indeed aerial
and ground UEs are served through a cellular network with a possible eavesdropper
that tries to intercept the message intended for permissible basic UEs
A cost-effective approach is to be used for coordination among ground BS and
UAVs to enhance secure transmission which is part of the UAVs acting as friendly
transmitters to degrade the wiretapping channels efficiency and thus enhance
secrecy efficiency A UAV acting as a mobile jammer can dramatically and
dynamically change its position as near as possible to the earth eavesdropper and
distribute them by sending the radio signals whereas strong LOS connection
characteristics are a beneficial feature with less earthly fading and shadowing
impairment
11
13 Unmanned Aerial Vehicle for 5G Networks
UAVs have technologically advanced as a revolutionary movement in delivering
pervasive connectivity from either the platforms of the sky as aerial
communication particularly for temporary User Equipment (UEs) (B Li et al
2019) Due to fully controllable UAV flexibility through miniaturization as well as
continuous cost reduction low-altitude UAVs are rapid and flexible designed for
operation and reconfiguration They are probable to have higher Line-of-Sight
(LoS) ties to ground UEs
A broad range of applications like inspection of infrastructure precision farming
and disaster area monitoring is becoming accessible in this aspect Moreover
further projects have also been set up to employ aerial platforms for broadband
access to distant elements such as the Google Loon and the Facebook Drone Project
to mention Highly populated UEs are desperate for broadband wireless
communications with the coming 5G period and network providers are supposed
to maintain numerous networks with high demands for wireless data like
multimedia streaming and also video downloads The relentless growth in the
amount of traffic of mobile networks puts a burden on operators in the form of
higher capital and operational expenditure Deploying small cell networks is an
intuitive alternative to outsource cellular traffic
Although in unforeseen or temporary events as mobile environments are
complicated volatile and heterogeneous the implementation of terrestrial
infrastructures is difficult The accessibility of aerial access points to enable
extensive complex connections is one possible solution However in unforeseen or
temporary events as mobile environments are complicated volatile and
heterogeneous the implementation of terrestrial infrastructures is difficult The
accessibility of aerial access points to enable extensive complex connections is one
possible solution UAV communication performance benefits from the simplicity
of the compact transceiver and progressive control methods that obtain broad
exposure and set up internet networks
12
Figure 13 UAV-assisted heterogeneous network architecture
The above Figure 13 is depicted to build flexibility of the network with enhanced
ability and elasticity It is a good network that offers security endowment This is
due to the transmitting information to UAV communication which is tapped
through ground unauthorized user and is known as an eavesdropper
Here through eavesdropper based on the upper layer cryptographic techniques
wireless communication in contradiction of unauthorized access has been protected
However it is very tough to achieve because of key management as well as more
computational difficulties in developing network architecture PLS affects the
characteristics of intrinsic wireless networks as a fascinating preparation such as
interference noise fading loss collecting signal characteristics in malicious
eavesdroppers and techniques of signal processing
14 Physical Layer Insecurity in UAV communication network
Jamming is either a well-defined WSN attack on a physical layer It disrupts the
radio waves being used by nodes of the network The attacker successively
expresses the denial of the simple MAC protocol over the wireless network The
impressive network can be disrupted at which a single frequency is being used
13
throughout a network (Modares et al 2011) In addition jamming can increase
energy consumption in the node by inserting impudent packets The receiver nodes
will also generate resources when receiving the packets In (Jeon 2006) four
different terms of jamming attacks that an intruder could use to interrupt the
wireless network activity Tampering is yet another physical layer assault
Table 11 Physical layer hazards and measures in UAV wireless
communication network
(Kumar et al 2014)
Hazard Security measures
Jamming Channel blacklisting and hopping
Interference Channel hopping and blacklisting
Tampering Security and key modification
Sybil Physical security of the system
Table 11 describes physical layer hazards and their security measures in WSN
which tampering and jamming are considered as the main attack in the physical
layer in WSN
141 Principles of security
The security requirement of UAV communication network is as follows (Kumar et
al 2014)
Confidentiality Ensure that only the approved sensor nodes could get the contents
of the texts
bull Authentication Ensure that the data is introduced from the sound source
bull Integrity Ensure that every received text has not been modified to be sent
by unauthorized users
14
bull Freshness Make confirm that no old information has been reiterated
bull Availability services are feasible at any time through WSN or by a single
node
The standard attacks of the physical layer are as follows (Sastry et al
2013)
bull Jamming The transmission of the radio signal can interfere only with radio
frequencies used through WSN which is known as jamming As the
capacity grows it may influence more significant portions of the network
by transmitting other radio signals The opponent will use a few nodes to
occupy the entire channel This state is called physical layer jamming which
results in a denial of service In this scenario the opponent will not be
permitted to have any knowledge but will be capable of preventing
communication to any nodes
bull Tampering Often the nodes tampered through an opponent This mode is
called tempering Here the attackers can destroy exchange and
electronically confront nodes to obtain information from counter measures
towards jamming that have been planned as spread as well as frequency
hopping
bull A security mechanism is used in WSN to track avoid and recover from
security attacks A wide range of security schemes can be devised to counter
malicious threats which can be classified as high and low levels
bull Secrecy and Authentication Most network sensor applications need
protection from eavesdropping packet alteration and injection Early
networks are used for connection layer cryptography as this approach offers
the easiest deployment of network cryptographic solutions
bull Privacy Like all other conventional networks the radio networks have also
brought secret issues to allow Initially sensor networks are implemented
for legitimate purposes and can eventually be used unexpectedly
Knowledge of active sensor nodes as well as the acquisition of data is
exceptionally crucial
15
bull Critical launch and trust setup The primary prerequisite for setting up a
network is the development of keys (cryptography) Sensor devices
typically have minimal computing capacity and public cryptographic
primitives are too difficult to adopt Critical establishment and strategies
need to be scaled to network with thousands of nodes
bull Secure routing Routing as well as data forwarding is a problem that
confronts to facilitate communication in networks Regrettably the latest
protocols encounter a variety of security flaws
bull Robustness of communication Does An opponent challenges to interrupt
the operation of the network
Figure 14 Security problems in the UAV
Figure 14 illustrated the security difficulties in a UAV The physical layer security
in the UAV wireless networks was examined The UAV had affected by both active
eavesdropper and passive eavesdropper This paper proposed the trajectory design
and cooperative UAV for constraining the eavesdropper NOMA MIMO mm-
Wave frequency band in UAV would cause better spectral efficiency and security
(Xiaofang Sun et al 2019)
UAV implementation of the 5G communication was considered advantageous The
UAV was assumed as the novel wireless network technique for the territory users
and their base stations The UAV had resulted in high altitude So the UAV had
16
considered a superior line of sight At the same time the possibility of security
problems was raised in a UAV The secrecy in the existence of eavesdropper the
jammer in the ground was performed using the UAV UAV aided territory security
was proposed The UAV was involved in inspecting the eavesdropper and hazard
jammers on the base stations territory UAV had targeted the global position system
spoofing for assisting the authentic users and performed the role of an artificial
eavesdropper for excluding the eavesdropper and jammers in the ground (H-M
Wang et al 2019)
15 Non-Orthogonal Multiple Access (NOMA) System Secured
Communication
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
151 Comparison of NOMA Vs OMA
Comparison of the NOMA and OMA can be discussed as follows
17
1511 Spectral throughput and efficiency
In OMA a resource is allotted to the distinct user whether it is good or bad in a
channel scenario like OFDMA Thus the whole process moves from less
throughput and performance
While the same frequency is allotted to the multiple-use at the same time with good
or bad channel operation in NOMA here the weak user gets the allocated for the
resources which the strong user can also use it And the interference can be reduced
by the SIC process on the receptor side of the user Consequently the probability
with the increased spectral efficiency as well the high throughput will be
maximized
1512 User fairness and higher lately
A user of fair channel complaints has higher precedence to be served in OMA In
contrast a user with a poor channel complaint is to remain activity which causes
the issue of user fairness and higher latency Yet OMA cannot assist colossal
connectivity Whereas NOMA helps multiple users with various channel
procedures and offers increased fairness massive connectivity and lower latency
1513 Compatibility
NOMA has compatibility with the current and upcoming scenario meanwhile no
need for necessary changes to the previous methods As an instance NOMA has
been bought up in the 3G Partnership Project LTE Advanced (3GPP LTE) Though
NOMA contains many characteristics that can assist the upcoming generations and
it has some restrictions that can be explored with its full benefits Those restrictions
are as follows
bull Each user has to decrypt the signals of other users until decrypted their
signal the complexity of the receiver would be strengthened in NOMA as
opposed to OMA which creates a long pause
bull Also data on channel quality for all users should be returned to the BS but
this results in substantial CSI input overhead Furthermore if any issues
arise to any consumer during the SIC process the likelihood of consecutive
decrypting errors will be improved
18
Figure 15 Comparative analysis of NOMA vrsquos OMA
As an outcome the number of users is reduced to ignore the spread of such
debugging Another aim of restricting the number of users is that there must be
substantial variations in channel revenues between users with different channel
grievances to provide network reliability
16 Problem Identification
The NOMA-based architectures main feature is to configure trusted and untrusted
users when more than one eavesdropper is present in the dense setting of todayrsquos
and future sophisticated wireless communication networks This research aims to
examine the security efficiency suggested for mission-critical applications in the
NOMA-based UAV communication network The proposed system underpins two
user NOMA frameworks The possibility of paring both users was explored with
PHY performance measures in mind Outage probability (OP) and Secrecy Outage
Probability (SOP) Dynamic Optimization Method Programming (DP) and Partially
Observable Markov Decision Process (POMDP) optimization have also been
analyzed to explore the feasibility of achieving an outage-optimal output for the
pair under the heavy users secrecy outage restriction The optimized theoretical
findings are applied to the multiuser scenario The identifications were tested
through a computer model in which POMDP has shown substantial progress over
the dynamic optimization method to program
19
17 Motivation
Unmanned aerial vehicle (UAV) wireless communications have experienced an
upsurge of interest in both military and civilian applications due to its high
mobility low cost on-demand deployment and inherent line-of-sight air-to-ground
channels However these benefits also make UAV wireless communication
systems vulnerable to malicious eavesdropping attacks
Despite the promising gains brought by UAVs the open nature of air-to-ground
wireless channels makes secure information transfer a challenging issue
specifically on the one hand information signals transmitted over wireless LoS
channels are likely to be intercepted by some undesired receivers which lead to a
risk of information leakage On the other hand wireless UAV transceivers are
vulnerable to malicious jamming attacks Hence security plays an extremely
important role in UAV wireless communications Unfortunately traditional
encryption techniques require high computational complexity leading to a large
amount of energy consumption which may not be suitable for UAV systems As an
alternative physical layer security is computationally efficient and effective in
safeguarding wireless communication networks via exploiting the inherent
randomness of wireless channels As a result various physical layer techniques
have been proposed in the literature for guaranteeing communication security
NOMA is viewed as a promising technique to provide superior spectral efficiency
by multiplexing information signals at different power levels [13] Hence it is
expected that NOMA can bring additional rate and robustness to enhance the
achievable rate in UAV physical layer security communications Consider a
scenario where a UAV acts as a relay to facilitate data delivery to two receivers
with different security clearance levels within a maximum cruising duration T The
receiver with a lower security clearance level and a higher potential with an
eavesdropper Since it has a strong motivation in intercepting signals intended for
a receiver with a higher security clearance Then when the eavesdropper suffers
from a bad channel condition NOMA is adopted to forward both confidential and
public information simultaneously Otherwise UAV only broadcasts the public
information for security issues The mode selection between NOMA and unicast is
20
chosen based on the results of the proposed resource allocation optimization In
particular for maximizing the spectral efficiency one needs to jointly optimize the
transmission scheme resource allocation and UAVrsquos trajectory However the
coupled optimization variables generally result in non-convex optimization
problems which are difficult to solve optimally As an alternative an iterative
suboptimal algorithm based on successive convex approximation can be employed
to facilitate a computationally efficient joint design We have discussed that the
NOMA scheme always outperforms OMA in all the considered scenarios which
demonstrates the spectral efficiency advantage brought by NOMA in striking a
balance between public data rate and confidential data rate
The main motive of this research is to enhance the inherently insecure PHY layer
of the NOMA-based UAV communication network NOMA-UAV communication
network requires feasible paring between trusted amp untrusted users (attacker) for
cooperative communication mainly in real-time field applications The power
allocation factor need to be optimized as per the trustworthiness of the associated
users (reliable user) and keeping the outage probability minimum for secured and
cooperative communications The pair Outage Probability and the SOP have been
optimized jointly for feasible pairing between BS amp the associated Users
18 Aim and Objective of the Research
The proposed works main objective is to examine the design of a NOMA-based
UAV communication network for enhanced Physical Layer security (PLS)
features Remarkably it is anticipated infrastructures and resources to connect
numerous devices and provide various services Researchers these days
concentrating on ways to design a heterogeneous framework like deployed small
cells air and ground-based deploy multifarious communication methods in 5G
such as millimeter-wave (mm-Wave) device-to-device (D2D) massive multiple-
input multiple-output (MIMO) Cognitive Radio (CR) and so on for improving
spectrum and energy efficiency
As a critical need especially for emergency applications the adoption of NOMA
transmission of UAV communication needs to be improved PLS A new optimal
resource allocation algorithm for some more robust and stable communication in
21
single and multiuser scenarios has been suggested here The PLS in dense
heterogeneous sensor networks has improved by the feasible pairing of trusted and
untrusted users (K Cao 2019 T Zhao 2018) In the instance of untrusted users
dynamic programming and POMDP are subjected to the channel conditions
details optimizing OP and SOP as a restricted parameter accompanied by resource
allocation (Davis 2018 L Hou 2018)
The main aim of the proposed research work areas
bull To analyze the underlying NOMA UAV communication framework with
enhanced Physical Layer security (PLS) implications for particular quest
applications
bull To examine the potential pairing of trusted and untrusted users in the
NOMA-based UAV contact network with two users and multiuser scenarios
for certain channel conditions called Channel State Information (CSI)
bull To maximize resource allocation among trusted and untrusted users by
pairing OP and Secret Outage Probability (SOP) as performance measures
with the POMDP optimization method
bull To evaluate POMDP and dynamic programming resource allocation with
two users and multiple users for both protected NOMA-based UAV
communication network scenarios
19 Thesis Organization
Chapter 1 Provides the introduction and basic concept of the proposed work with
the problem identification motivation and aim and objective of the proposed work
Here we described LTE 4G and its advanced techniques than about the NOMA and
its basic scheme UAV concepts represent their types and basic working strategy
Chapter 2 Provides a survey of the existing technologies which is related to the
proposed work The NOMA transmission schemes Merits and De-merits related
to security UAV assisted communication in heterogeneous sensor networks UAV
networks of 5G and beyond communications has been explained then about UAV-
NOMA PHY secured communication techniques as well
22
Chapter 3 Describes the proposed work of improvement of physical layer
insecurity of the NOMA The overflow and its performance measures with
simulated output have been defined in this chapter
Chapter 4 Describes Migrations proposed work from 4G LTE to advanced PHY
techniques for UAV communication The overflow and its performance measures
with simulated output have been explained in this chapter Concludes and explains
the proposed work with its outcome and the future scope of the proposed work
23
CHAPTER 2
LITERATURE REVIEW
21 Integration of UAV Networks for 5G and B5G communication
5G and B5G had been anticipated to give a unique connection among universal
users The UAV had been emerged for its advantage of wireless network and
relaying high data rate The UAV in the 5G and B5G was introduced and 5G and
B5G were updated with the new concept of Space-Air-Ground Integrated Networks
(SAGIN) Three layers were established named physical network communication
link and evaluation Besides the usage among the dense population IoT was
applied in satellite communication In which the IoT had provided the uninterrupted
service with high data rate communication The scope for flying UAVs had been
created for enhancing the number of mobile users with IoT (Ali et al 2018)
5G and B5G had projected the UAV as the vital constituent One to multiple point
transmission can be possibly advance in 5G and B5G The structural design of the
upcoming UAV (multi-tier drones) was driven by the routine of different structures
like the maximum functioning altitude communication overlap coverage and
determination The UAVs practicability (multi-tier drones) among conventional
UAVs (single-tier drones) is scrutinized in that perspective By ascertaining the
circumstances UAV (multi-tier drones) could supplement the older terrestrial
networks with RF Initially UAV (multi-tier drones) and drone-aided wireless
networks were related to finding the tasks The modified UAV (multi-tier drones)
and the drone-administered wireless networks were analyzed The enactments of
UAV (multi-tier drones) were scrutinized in the contest of spectral efficiency in the
downlink networks Their effect had exhibited the detailed network parameters The
UAV distribution (multi-tier drones) was considered advantageous for the spectral
efficiency from the downlink transmission over traditional terrestrial wireless
networks (Sekander et al 2018)
The growth of 5G and B5G wireless networks prominently hang on the
incorporation of the terrestrial and aerial systems in innovative heterogeneous
network architecture They had advanced a creative and tangible multiple UAV
24
made up of cluster UAV ndash base stations and Poisson point process with UAV and
mm-Wave frequency band Ground user equipment and UAV had exhibited as the
Poisson cluster process and then spread around the public cluster in the distinctive
cluster In particular the scrutiny was accompanied by the accumulation of extra
tiers Extra tiers were made up of multi-cluster UAV base stations and single ground
user base stations in the characteristic cluster Four-tier network systems were
designed correspondingly from the subdivision of the above-said base stations
Two-tier and four-tier association patterns were built for discovering the
involvement of the cluster networks The coverage probability for the downlink and
network throughput was derived (Ji et al 2020) The numerous subordinate title
role of the multifaceted communication systems was performed by the UAVs The
UAV was acted as the air relay in the maintenance of ground networks The UAVs
were used in the countryside hilly zones whereas the communication was
inadequate The author anticipated resolving the viable communication difficulty in
5G and B5G vehicular ad-hoc The associate communication pattern established on
the smart UAVs was planned given the crisis condition of the car ad-hoc The smart
UAVs were supporting the vehicular ad-hoc strong communication in real
situations Above and beyond its actual characteristics of the vehicular ad-hoc were
needed to be endangered to avoid the prohibited features from attaining and
exhausting for law-breaking practices Innovative UAV with a secret authentication
key arrangement was recommended in the 5G and B5G vehicular ad-hoc Because
of supporting efficiency the vehicle network which guaranteed communication
confidentiality was not negotiated The suggested pattern was confirmed to be
unaffected by numerous outbreaks by exploiting the broadly applied natural or
random ROR scheme
Furthermore the projected scheme had well calibrated the communication
overhead from the performance estimation (J Zhang et al 2020) The UANs had
obtained a phenomenal role in the research area the emergent sector of aerial
robotics The parcel transport organization monitoring occurrence shooting
surveillance and tracing were the metropolises general operations utilizing the
UAV Various domains would use 5G and B5G to improve UAV networks UAV
ecological unit was advantageous in present 5G and B5G mobile communications
For UAVs intrinsic features they were concerned for flexible movement of three-
25
dimensional space independent actions and smart locations These devices were
provided with extensive scope in cellular networks The author proposed an in-
depth assessment of implementing cooperation between UAV and 5G and B5G In
which UAV had been assimilated as a novel user equipment of aerial in present
mobile communications The UAV had implemented the duty of flying users within
the network coverage named the cellular-connected UAVs in this amalgamation
The author showed a broad examination of the incorporation tasks with 5G and
B5G novelties Continued efforts in the prototyping and validation of mobile
communication UAVs were conducted using the ground trial The paper had
focused on the current growth in 3GPP The social-economic had not been taken
into account which was considered disadvantageous (Mishra amp Natalizio 2020)
The UAV was anticipated as the significant constituent in the 5G and B5G wireless
networks 5G enables the UAV to be used in broadcasting and end-to-end
communications using the small UAV They needed a devoted and endangered
aerial spectrum in the aircraft cargo by letting small UAVs run in space in
supervisory authority The security information was obtained from the link Control
and Non-Payload Communications (CNPC) The security information contained
the regulation of UAV and the line of sight of terrestrial The CNPC application in
the 5G and satellite communication was scrutinized in this paper Payload
communication like mm-Wave networks and UAV were analyzed in this paper The
direction-finding and reconnaissance difficulties were examined UAV
communication systems were scrutinized and the hardware challenges were
discussed (Hosseini et al 2019)
The potential gain from the UAV-assisted data gathering was found in
indiscriminate IoTs The characteristic propagation was represented by utilizing the
complicated channel method (contained small- and large-scale fading) IoTs were
updated in constrain of transmit power (in high) and total energy The multi-antenna
UAV was selected in the IoTs in sequence The virtual MIMO was created by the
communication between UAV and singe antenna IoT in every transmission (W
Feng et al 2018)
The UAV was applied in the aerial coverage surveillance agricultural prediction
constructional areas and power line supervising and blood donation The flight
26
period increment payload capability fast movement and speedy placements were
implied features in the UAV so that the UAV was exploited by the applications of
5G and B5G (Ullah et al 2020)
The UAV was considered a motivation for many emergent usages and reformed
social-economic welfares The wireless networks for the UAV and the base stations
were desired for the UAV function Mobile communications were considered
suitable for finding tracing and regulating the flying UAV The wireless
communications were selected for their features of broad coverage quality of
service and secrecy The wireless communication in the UAV improved
productivity besides the line of sight (G Yang et al 2018)
22 UAV-NOMA in Physical Layer Security enhancement
The NOMA has been applied in the fifth generation (5G) technology The Multicast
Cognitive Radio (MCR) network is implemented using the NOMA and coined as
MCR- MOMA The transmission side is also included with the superimposition
code The decoding was applied at the receiving end So an unknown user is
deduced in their methodology (Meng et al 2020)
The physical layer security for the cooperative NOMA was examined Amplify
and forward decode and forward were taken into consideration for achieving
secure transmission (Chen et al 2018)
The physical layer security of the NOMA was analyzed in the broader network with
varying locality The single and multi-antenna were established in the following
cases The single antenna was taken for an end-to-end connection in a secured
manner And the multi-antenna was used for the connection of base station and
random user Finally achieved security for the multi-antenna on the transmission
side The security of the single antenna was attained by introducing the excluding
area for eliminating eavesdroppers The individual expression of security outage
probability for both single antenna and multi-antenna were derived (Yuanwei Liu
et al 2017)
The secure transmission of NOMA in large-scale applications was investigated
Stochastic Geometry was utilized for placing the eavesdropper and user nodes The
equation for secrecy outage probability was derived and expressed for evaluating
27
secure transmission Security can be improved by expanding the protected zone
(Qin et al 2016)
The power domain NOMA had the disadvantage of decoding data by other
unauthentic users of the same source For reducing unauthentic users the base
station should treat the unauthentic users with different cleaning methods The
secrecy outage probability was investigated for authentic users and unauthentic
users Both users were combined as a pair to the non-uniform distribution of original
and unauthentic users The pair outage probability of genuine users from the secrecy
outage probability restrained NOMA authentic users The derivation for pair outage
probability and the secrecy probability were expressed for calibration The
combined system had been the better security (ElHalawany amp Wu 2018)
The physical layer security was considered problematic in the wireless networks
mainly for keeping the authentic userrsquos data The UAV was acted as the base
station UAV based base station had sent the extensive data to the original users
NOMA with the multi-antenna with mm-Wave frequency band transmission had
enhanced the spectral efficiency The physical layer security was attained by
announcing the space around user locality as the eavesdroppers protected zone
Covering the entire eavesdropper area was considered a resource-consuming way
The shape optimization for the protected location in each UAV base stations
altitudes was introduced The derivations for the secrecy sum rate and the secrecy
outage probability were expressed (Rupasinghe et al 2018)
The vehicular communication system had used cooperative NOMA The secrecy
outage probability was considered in vehicular communication The relay can be
used in both modes (half-duplex and full-duplex) in vehicular communication The
closed derivation for the secrecy outage probability was expressed The security of
the full-duplex NOMA resulted better than that of the half-duplex NOMA The
limitations are that the velocity of the vehicles was not considered Figure 21 is
illustrated the conceptual model of the vehicular communication NOMA system
(Xie et al 2019)
28
Figure 21 Vehicular communication NOMA system
The physical layer security of the uplink NOMA of the large-scale devices was
examined The connection networks had investigated with the approach called
stochastic geometry The new derivation was expressed for the coverage
probability The protected zone restrains eavesdroppers to the authentic users
Efficiency secrecy throughput was examined wiretap channels and the many
original users Constant transmission and variable transmission were collectively
inspected The signal to noise and the movement to interference ratio were derived
drastically (Gomez et al 2017)
The wireless system was executed using Space-Time Block Coding (STBC)
approach in the NOMA of mm-Wave MIMO The technique focused on haphazard
users So the pairing method was introduced mainly for Random Near-Random Far
(RNRF) Here the latent period could be minimized and the RNRF has also been
deduced for the overhead issue The result revealed the systems efficiency with a
proper implementation (Ghavidel et al 2020)
The recent arbitrary beam forming method was proposed in the multiple access
NOMA The pairing had decided to the user places So the evaluation was focused
on the system overhead The result revealed that the proposed work outperformed
29
the existing methods (Aghdam et al 2020) NOMA enhances the reliability of
multi-users transmission The sum rate could be reduced for improving Quality of
Service (QoS) power transmission and signal outage probability The
eavesdropper easily accessed the multi-access systems that cause physical security
during transmission (Z Li et al 2020)
The NOMA had provided spectral efficiency speed transmission of data multiple
networking and less latent period The NOMA utilizes the power domains for
various access Cognitive Radio Networks (CRN) is used to screen illegitimate
users The legitimate users were only permitted in the CRN by the Primary User
Networks (PUN) QoS The cooperative NOMA here implemented with the PUN
and the system performance is enhanced The spectral efficiency can be improved
by the secured transmission The cooperative NOMA was additionally developed
in the CRN with the PLS A new method of cooperative NOMA in the CRN was
examined The PUN technique attains a secure transmission Multiple antennae
were used in this study for reliability and the eavesdropperndashexclusion zone method
is used for better security (B Li et al 2018)
The downlink NOMA for moderate CSI was examined The challenge of the power
domain was rectified by allocating power NOMA The power in NOMA and that
of the OMA was analyzed which resulted in a significantly reduced NOMA (Cui
et al 2016)
Here the users were multiplexed by the power domain So the method was coined
as power domain NOMA The demand arising from the B5G (Beyond 5
Generation) had reached using power domain NOMA Machine learning in the
NOMA was described (Maraqa et al 2020)
The uplink NOMA with the PLS was proposed The uplink NOMA contained a
single base station and multi-users a couple of users combined for NOMA The
known jammer emitted the pseudo-noise to divert the eavesdroppers The study had
suggested the two jammers in the uplink NOMA for secure transmission (N Zhao
et al 2020)
The Intelligent Reflecting Surface (IRS) is designed using downlink NOMA The
multi-access had used the space direction of the beams of closure users The IRS
30
had performed the multi-access for every spatial order by the cell edge users of the
orthogonal beams (Ding amp Poor 2020)
The multi-input single-output NOMA has introduced the technique called Secrecy
Beam Forming (SBF) SBF had utilized the artificial noise for NOMA security
aided users in which the eavesdropperrsquos channels deteriorated The SBFs secure
transmission can be achieved in which high successive interference cancellation is
gained (L Lv et al 2018)
The superposition coding was performed in the transmission pat The successive
interference cancellation was conducted in the receiving position These two
techniques were combined in the novel 5G aided NOMA The basic concepts of
uplink and downlink NOMA were mentioned The dominant condition was
performed in the two user clusters of NOMA The prevailing state had issued the
confirmed spectral efficiency gain in NOMA (Tabassum et al 2016)
The relay scheme in IoT was examined for the secrecy of NOMA This was coined
as relay selection NOMA The base station had transmitted the secret messages to
the two NOMA-aided sensors and eavesdroppers IoT had treated the sensors and
eavesdroppers with different power allocations The expression for certain outage
probability and the strictly positive secure capacity was derived Increasing the
number of the relay would enhance the security in the NOMA-aided IoT The
outage probability for NOMA and OMA were compared The NOMA resulted in
better outage probability in Decode and forward mode (Do et al 2019)
31
Figure 22 RS-NOMA against an external eavesdropper
The NOMA-aided IoT was utilized to fight against the external eavesdropper as
Figure 22 The secured NOMA was proposed The base station sent secret
messages to several authentic destinationsmdashseveral eavesdroppers and unauthentic
users
Nakagami-m fading model was carried out using the multiple antennae in the
channel The security was attained using the max-min transmit antenna selection
scheme Both authentic and unauthentic eavesdroppers were analyzed The closed
derivation for the cumulative distribution of the original user was expressed first
That was compared with the unauthentic user The derivation for the secrecy outage
probability was obtained to identify the level of secrecy performance (Lei et al
2018)
Reconfigurable intelligent surface (RIS) aided NOMA was established for the
secrecy performance The main disadvantage of this model was the chance of using
RIS by the eavesdropper The secret outage probability was derived in this paper
The RIS improved the secrecy of the traditional NOMA The eavesdroppers were
limited from receiving the RIS signal by enhancing the number of intelligent
elements in the RIS A high signal-to-noise ratio was obtained from this experiment
(Liang Yang amp Yuan 2020)
32
The cooperative relaying NOMA was proposed for improving private transmission
in wireless networks Full duplex mode transmitted the jamming signals That
received the required communication at first Secondly the jamming signal
emission was sent by the base station The power allocation for the jamming signal
and information signal was decided on the eavesdropper channel state information
The eavesdropper was jammed by the signal from the first phase with maximum
power Second the derivation of the secrecy outage probability was expressed by
static eavesdropper CSI (Y Cao et al 2020)
The NOMA achieved spectral efficiency and secrecy The security of the multi-
NOMA users was obtained by the successive interference cancellation (SIC)
decoding in the receiving node The conservation of the untrusted NOMA was
concentrated in this study The security can be confirmed by the properly secured
decode processing and allocating power The decoding scheme was implemented
for aiding NOMA users The decoding was performed for enhancing the sum-rate
(Thapar et al 2020) The cognitive radio network in NOMA with the external
eavesdropper was proposed (Mehr et al 2020)
The cooperative NOMA was used in the field of energy harvesting communication
The novel relaying technique was introduced for achieving secrecy The secrecy
outage probability was derived and the derivation was expressed for the three
conditions The first condition was the derivation of CSI with a passive
eavesdropper The second condition was the derivation of CSI with the unauthentic
eavesdropper The third condition was the derivation obtained from the multi-relay
nodes The increased SNR resulted in high security The increase in the number of
users deduced security This was considered a disadvantage (Salem et al 2020)
Satellite communication covered more range of broadcasting So the security
challenge was considered a big difficulty in satellite communication Downlink
NOMA was assessed with an eavesdropper for the examination of secrecy The
paper concentrated on the physical layer security of downlink satellites Here two
methods were proposed The frequency-domain NOMA was considered for gaining
spectral efficiency The multiple user interferences were obtained in the process of
overlapping Introducing a suitable technique can be performed the security for the
number of users The secrecy rate was analyzed for all authentic users (and the
33
eavesdropper) and expressed in the derivation The safety was improved using the
spectral overlap method (Yin et al 2019)
The NOMA was considered as the emerging scheme in the upcoming wireless
networks The secrecy sum rate for the downlink NOMA (with MIMO multiple
inputs multiple outputs) was examined Downlink NOMA had the base station
number of users and the eavesdropper In the limitation of transmit power and
optimal successive interference cancellation the security was expected to enhance
Downlink MIMO NOMA was considered advantageous because of its secrecy
performance and the practical usage of bandwidth The mutual information rate and
the mean square error were causing the secrecy rate optimization to the problem of
biconvex This was rectified through the alternative optimization method and the
second-order cone programming was solved (Tian et al 2017)
Table 21 Comparative analysis
The comparative analysis for the physical layer security was examined in existing
studies
SR
No
Details of Author wise Contribution to NOMA Technology
1 Author (YFeng Yang amp Yan 2017) Secrecy performance in NOMA was
conducted with the help of artificial noise in the full-duplex mode of relaying
Methodology The optimization of the power was calibrated for the source
information and the noise signal The closed derivation for the secrecy outage
probability was expressed
Usage and limitations The physical security was increased
34
2 Author (He Liu Yang amp Lau 2017) NOMA was developed in the constrain
of security
Methodology The secret message had been sent to some users and also to the
eavesdropper The Novel decoding process was conducted for excluding the
unauthentic users The iterative algorithm was used for power optimization
Usage and limitations Transmit power was reduced The quality of service
was availed
3 Author (D Wang et al 2020) The secrecy was performed in the NOMA
The security was developed against the eavesdropper outside
Methodology The channel state information was analyzed for secrecy The
quantization of CSI had performed for secrecy The derivation for the secrecy
and transmission outage probabilities were obtained
Usage and limitations The secrecy rate was enhanced
4 Author (L Lv et al 2020) The physical security of the NOMA was
improved by adding artificial noise jammer and inter-user interference The
mode of full-duplex in the updated version was used in the NOMA
Methodology The eavesdropper can be trapped the superimposed signal from
the source So the secrecy was affected
Usage and limitations The spectrum usage is effective in the NOMA
transmission scheme Numerous connections can be performed in the NOMA
NOMA is considered to be the most advantageous for the upcoming
generation communications The superimposition technique was followed
4 Author (Yue et al 2020) Secrecy performance of the NOMA was developed
with a unique framework
Methodology The eavesdroppers inside the zone and outside the coverage
zone were examined properly in this paper The outage probability for codendash
power domain NOMA was derived
Usage and limitations Safety was acquired for both internal eavesdropper
and external eavesdropper in this scheme
35
5 Author (Guezouli et al 2020) The heterogeneous sensor network of cellular
communication was taken into account
Methodology Unmanned aerial vehicles are utilized the heterogeneous
sensor network of cellular communication
Usage and limitations Extended the life span of the network system The
cost of the hardware components is drastically low The random and the
repeats in the speedy movement The latency is maximized The coverage
period is maximum
6 Author (Yao amp Xu 2019) The security in transmitting a large amount of
information in the wireless network systems are analyzed with unmanned
aerial vehicle UAV
Methodology The numbers of UAVs are arranged in the space The base
station sent the information to the UAV in the space The authentic receivers
have obtained the secured information from the UAV The HPPP
homogeneous Poisson point process is used for distributing the authentic
receiver and eavesdropper in the line of sight
Usage and limitations The increase in the number of safety zone causing the
secured transmission
7 Author (Saacutenchez et al 2020) Physical security can be achieved by the
method of a unique encryption scheme
Methodology The physical layer security of the following schemes is
discussed in this paper mm-wave NOMA massive multi-input multi-output
heterogeneous sensor networks full-duplex mode
Usage and limitations The physical layer security was analyzed for the 5G
supporting technologies Good reliability achieved The less latent obtained
Machine-type communications can be enabled
36
8 Author (Hou et al 2018) The multi-antennas were used in NOMA with
UAV The stochastic geometric approach was examined
Methodology The multi-input multi-output kind of NOMA was utilized In
common the stochastic geometric approach was used for drastically moving
NOMA
Usage and limitations The maximum signal-to-noise ratio was obtained in
this scheme Power optimization was achieved The path loss is less Good
spectral efficiency was obtained
9 Author (Miao et al 2020) The broadcast type of communication was
performed The less weighed three-dimensional space for 5G communication
was analyzed
Methodology Both the performances of multicast and broadcast were
enabled UAV-assisted 5G communication systems are emerging in the
upcoming wireless networks
Usage and limitations Better flexibility in the network Continuous mobility
One lined line of sight
10 Author (Majhi amp Mitra 2020) The secure communication in cognitive radio
by NOMA was propounded
Methodology The antenna strategy of giving minimum outage probability
was concluded from this study
Usage and limitations The limitation is that more spectral efficiency causes
security issues
11 Author (X Zhao amp Sun 2020) Secure communication of the physical layer
in Visible light NOMA Communication was proposed
Methodology Energy optimization in security constrain was propounded for
achieving overall performance
Usage and limitations It is difficult to find optimal results because energy
optimization is the nonconvex issue
37
12 Author (Tuan amp Hong 2020) Secure communication in simultaneous
wireless information and power transfer NOMA was remitted
Methodology Eavesdropper is used for security purposes between the user
and base station using energy relays Known jammer is used for secure
transmission For energy efficiency storing and transferring were propounded
Usage and limitations Jamming requires extra power allocation
13 Author (Vaezi et al 2019) NOMA for 5G in mmWave MIMO cooperative
and cognitive were analyzed in this study
Methodology SWIFT NOMA is useful for weak receivers
MIMO using more antenna
Usage and limitations multi-antenna utilization cause high power
consumption
14 Author (Vaezi et al 2019) Mobile edge computing NOMA was proposed to
optimize power
Methodology Minimum latency and less power consumption
Usage and limitations Transfer power allocation must be calibrated
15 Author (Faraji-Biregani amp Fotohi 2020) Security in UAV communication
was proposed by introducing mobile agents
Methodology Malicious user of UAV was identified
Usage and limitations Three-phase power is essential
16 Author (G Zhang et al 2019) Secure communication in 5G UAV was
propounded by joint trajectory carrying out in physical layer
Methodology Power optimization was proposed for security
Usage and limitations Security in the physical layer was achieved by
optimization of trajectory
17 Author (Fotohi et al 2020) Agent-based self-protection was propounded in
UAN for secure communication
Methodology This method imitates the immune system of human beings
Less cost
Usage and limitations Energy is not optimized properly This approach
needs to consider other malicious attackers
38
18 Author (Shang Liu Ma amp Fan 2019) Vehicle to everything approach was
propounded for security in a UAV
Methodology Security of vehicle to the vehicle was proposed by considering
eavesdroppers active and passive attacks
Usage and limitations High price
19 Author (Kantor et al 2017) The flight path was calibrated in a UAV
Methodology Security performance was achieved by encryption as well as
anonymization
Usage and limitations High in cost and hardware structure occupies more
place
23 Research Methodology
The NOMA-based cellular architecture for UAV communication has been
considered here as reference network architecture Rayleigh fading has been
assumed as a channel characteristic The performance parameters for PHY layer
security are (1) Pair Outage probability (Pair OP) between two users trusted near
user designated as U1 and untrusted far user designated as U2) and (02) Secrecy
Outage Probability (SOP) of trusted near user designated as U1 The aim is to
achieve optimal Pair OP for the given constrained SOP of User U1 so that network
resources can be efficiently allocated to both users without compromising the
secrecy of trusted User U1
The mathematical analysis from reference literature (ElHalawany et al 2018) has
verified and supported the joint optimization of the Pair OP and SOP for the given
power allocation factor in NOMA This research work is extended as providing
more efficient resource allocation using the POMDP algorithm in a given scenario
First the varying distance of untrusted user U2 from BS as a critical selection
parameter that affects Pair OP amp SOP of user U1 and U2 both has been simulated
and the feasible and infeasible pairing of both users have been analyzed The
optimal power allocation factor for feasible pairing as the constrained problem is
optimized by opting for POMDP as a resource allocation algorithm wherein the
SOP of user U1 is strictly maintained for given CSI POMDP provides optimum
39
power allocation factor for trusted and untrusted users pairing as shown in the
proposed flow of POMDP algorithm is used to model a variety of real-world
sequential decision-making problems After the BS has been set up the distance
between the BS and the user is calculated and if space is less than 200m it is
defined as a trusted user While if the range is more than 200m it is described as
untrusted users In the case of trusted users the channel state information (CSI) is
provided to the proposed algorithm POMDP for reliable and efficient resource
allocation
24 Summary
UAVs play a central role in providing network service recovery in a disaster-
stricken region enhancing public safety networks or handling other emergencies
when Ultra-Reliable Low-Latency Communication is required In particular UAV-
assisted communication can be regarded as an important complement to the 5G
cellular networks Surveyed literature related to UAV communications published
over the past several years emphasized the cybersecurity and channel modeling for
UAV communications etc Security is one of the critical issues in communications
Modern communication networks are based on the layered architecture from the
physical layer up to the application layer A great deal of effort has been made to
develop the cryptographic protocols above the physical layer However the
physical layer is not as robust as that in wired communications The physical layer
in wireless communication is more complex than the counterpart in other
communication paradigms The concerns come from not only the noises but also
many types of fading Recently there has been an influential interest in studying
the security issues in the physical layer Security is highlighted as another
challenge and the implementation of physical layer security techniques is seen as
a difficult task PHY security in NOMA systems under the presence of external
eavesdroppers or untrusted relay nodes Upcoming 5G networks for unpredicted or
crisis (disaster management) the placement of terrestrial substructures is
economically infeasible and challenging due to high operational expenditure as well
as sophisticated and volatile environments
To address such novel issues intelligent heterogeneous architecture by leverage
UAV has been well-thought-out to be a promising novel model For advancing the
40
performance of the UAV 5G communication system physical layer techniques are
of many effects as they have impacted the applications of UAVs Security of
NOMA-based UAV communication network has been scrutinized for optimization
as physical layer security
41
CHAPTER-3
SYSTEM MODEL FOR NOMA-UAV
COMMUNICATION
31 NOMA-UAV System Secured Communication for 5G
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
311 The basic scheme of NOMA
The NOMA system allowed several users to be served simultaneously by the
transmitter To transfer a linear combination of different signals towards the
recipient the system of proportional representation superposition coding (SC) The
transformed signal is provided through
σ ඥ119875119896 119878119896119870119896 =1 -------------------------------------- (1)
Where 119927119948 represents the transmit power assigned toward user k th
119930119948 indicates the normalized message used for user k th
42
The instantaneous total converses power is σ 119927119948119922119948=1 The received signal at user kth
and the eavesdropper are offered through
119910119896 = ℎ119896 σ ඥ119875119896 119878119896119870119896=1 + 119899119896 -------------------------- (2)
119910119890 = ℎ119890 σ ඥ119875119896 119878119896119870119896=1 + 119899119890 -------------------------- (3)
Where 119951119948 and 119951119942 indicated the zero-mean Additive White Gaussian Noise
(AWGN) at user k th with variance 1205901198962 and the zero mean AWGN at eavesdropper
with variance 1206481199422 respectively We assume that the noise variances at all the users
are identical
ie 12059012 = ⋯ = 120590119896
2 = 1205901198902
As per NOMAs process the SIC is followed by all users to decrypt the message to
the same decoding order Notice that it is not known what the optimal decoding
order is for the NOMA method that corresponds to secrecy
Therefore the mth message to be encoded to the user might not be the mth message
to the user As such we also have to add the π variable For example if 120587(1) =
3 then the first message to be decoded for the SIC is the message for the user 120645(119947)
forall j lt k before decoding its letter to remove the inter-user interference successively
Then the user 120645(119948) denotes its message while treating the news for all the user
120645(119946)foralli gt k as the interferences The received Signal-to-interference-plus ndashnoise
ratio (SINRs) at user 120587(119896) k lt K and user 120587(119870) to decode their messages are
respectively given by
119878119868119873119877120587119896=
120574120587(119896)119875120587(119896)
1+120574120587(119896) σ 119875120587(119894)119896119894=119896+1
119896 lt 119870 --------------------(4)
119878119868119873119877120587119870= 120574120587(119870)119875120587(119870) --------------------------------------(5)
Were 120574120587(119896) =หℎ120587(119896)ห
2
1205901199062
൘
43
Also the acknowledged SINR at user 120587(119898) to decrypt the message 120633120645(119948) 119896 lt
119898 le 119870 is given by
119878119868119873119877120587119896=
120574120587(119898)119875120587(119896)
1+120574120587(119898) σ 119875120587(119894)119896119894=119896+1
kltmle 119870 --------------(6)
Similarly the acknowledged SINRs by the eavesdropper of the message 120575119896 119896 lt
119870 and the message 120575119896 are respectively given by
119878119868119873119877120587macr
119896=
120574119890119875120587(119896)
1+120574119890 σ 119875120587(119894)119896119894=119896+1
klt119870 ----------------- ------(7)
119878119868119873119877120587macr
119896=
ȁℎ119890ȁ2119875120587(119896)
1205901198902 = 120574119890119875120587(119896) klt119870 ---------------------(8)
Where 120574119890=ȁℎ119890ȁ2
1205901198902൘
Notice that here expressions for the obtained SINRs at eavesdropper overestimate
the skill of eavesdropper Here a worst-case inference from the viewpoint of
legitimate users is made That is the messages have already been decrypted by the
eavesdropper for all users π (j) forall j lt k before attempting to decrypt the message
for the user π (k)
The presumption also assumes that the decrypting order and power distribution are
understood by the eavesdropper The eavesdropper may or may not recognize the
decoding order of the users and the allocation of power may or may not recognize
the messages for all users π (j) forall j lt k before attempting to decode messages for
users π (k) However since the eavesdropper has been unable to alert the authorized
customers of its capacity and the current CSI the approved user would be unable
to know the eavesdroppers details Therefore we have to pursue the worst-case
scenario for the permissible users point of view due to the liberality required by the
safety reports It highlights that the worst-case assumption in the study and design
of transmission schemes with secrecy requirements has been generally adopted
The proposed study has been evaluated using performance measures Here we
analyze NOMA with downlink and uplink networks suggested by SINR and Sum
44
Rate survey High SNR is then simulated to contrast the OMA and NOMA
processes
312 Downlink of NOMA
The Downlink of the NOMA network on the transmitter side is described in Figure
31 SIC method is supposed to be carried out successively on the receiver side of
each user until another signal is restored The coefficients of users are owed in an
inversely proportional manner based on their available bandwidth
Figure 31 Downlink NOMA network
A consumer with a poor available bandwidth has a transmission capacity of a
higher range than a consumer with strong available bandwidth As a consequence
the consumer with the higher power assumes the signals of other users to be noisy
and automatically restores the signal without conducting any SIC operation The
receiver of each consumer detects indications that are stronger than those of the
desired signal These impulses are then deducted from the power and this process
continues until the signal has been calculated Both users decrypt their signaling by
considering other users with lower correlations The signal is calculated as
45
119904 = σ 119886119894119875119904119883119894119871119894=1 -----------------------------------------------(1)
Where Xi is the user ithrsquos information through unit energy
Ps is the capacity of transmission at the BS
ti is the coefficient of power assigned for user i
Although without the need for lack of generality the channel profits are expected
to be graded as ȁℎ1ȁ2 le ȁℎ2ȁ2 le ⋯ ȁℎ119871ȁ2
Where 119945119923 is the coefficient of the channel of the user Lth
The received signal of the Lth user is calculated as
1199101 = ℎ119897119904 + 119899119897 = ℎ119897 σ ξ119886119894119875119904119883119894119871119894=1 + 119899119897 -----------------------------(2)
Where n1 is zero mean Complex Gaussian noise with a variance of 1206482SINR
analysis with the equation (2) the SNR of Lth user to identify the user 119895 le 1with
119895 ne 1
119878119868119873119877119871 = 1198861120574 ȁℎ1ȁ2120574ȁℎ1ȁ2൘ σ 119886119894 + 1119871
119894=119871+1 ------------------------(3)
Where 120632 = 1198751199041205902ൗ represents the SNR
Sum rate analysis After identifying the SINR of the downlink the sum rate will
also be done quickly
The NOMAs downlink data rate of Lth user can be calculated as
1198771119873119874119872119860minus119889 = 1198971199001198922(1 + 119878119868119873119877119871) --------------------(4)
313 Uplink of NOMA
The Uplink NOMA is depicted in Figure 32 where each user sends a signal to the
BS SIC iterations are supported to classify the signals of mobile users If both
channels are identical and BS sends the coefficients of power allocation to mobile
users the received signal can be interpreted as a synchronous uplink to the NOMA
46
119955 = σ ℎ119894ඥ119886119894119875119909119894119871119894=1 +n ----------------------------------(5)
Where hi is the coefficient of the channel for the ith user
119927119961119946 is the extreme transmission capacity supposed to be general to all users
N is zero-mean Gaussian noise with a variance of 1206482
Figure 32 Uplink NOMA
Analysis of SINR The BS decrypts the signals of the users as per the coefficients
of the users and the SINR for the Lth user can be defined as
119878119868119873119877119871 = 119886119897120574ȁℎ119897ȁ2120574 σ 119886119894ȁℎ119894ȁ2 + 1119897minus1
119894=1൘ ----------------------------(6)
Where 120574 = 1198751205902ൗ indicates SNR
Analysis of Sum rate The sum rate of uplink NOMA when 120632 minus infin can be
computed as
119877119904119906119898119873119874119872119860minus119906 asymp 1198971199001198922(120574 σ ȁℎ119897ȁ119871
119894=1 2 ------------------------ (7)
47
314 Comparison of NOMA and OMA
The attainable data rate of the Lth user of OMA intended for both uplink as well as
the downlink is estimated as
119877119904119906119898119874119872119860 = σ 120572 1198971199001198922120574(1 +
120573119897ȁℎ119897ȁ2
120572119897119871119894=1 ) --------------------------(8)
Just for convenience two users should evaluate the summation of uplink rates for
NOMA and OMA The use of both the uplink rate of NOMA and OMA at high
SNR can be calculated as---
119877119904119906119898119873119874119872119860 asymp 1198971199001198922(120574 ȁℎ1ȁ2 + 120574ȁℎ2ȁ2 ------------------------- (9)
equation (7) and (8) it is seen that 119877119904119906119898119874119872119860 le 119877119904119906119898
119873119874119872119860
Here we note 119929119956119958119950119926119924119912 le 119929119956119958119950
119925119926119924119912 shows that NOMA performed better than OMA in
terms of sum rate in both downlinks as well as uplink of two user networks
The sum rate will be calculated after the SNR as the formulation is shown In this
proposed work multiple users are propagated to the process of NOMA and here a
comparison of NOMA as well OMA has been defined The NOMA uplink and
downlink using the OFDMA method for the
32 PLS performance metrics in NOMA -UAV communication
This chapter mainly describes the proposed work to examine the availability of the
outage probability of the pair below an authorized user According to the decryption
of SIC availability and spectrum sharing the unauthorized user can function as an
eavesdropper and obtain an outage probability (OP) for all situations with the
Secrecy Outage Probability (SOP)
321 SOP and OP - two user and multi-user NOMA system
NOMA system has the capability for assigning multiple data over the transmission
signal through high-level coding (Shim amp An 2018) Thus it contains spectrum
efficiency when opposed to OMA But this has a limitation in security As an
48
instance if the eavesdropper is reached then it obtains multiple user data in the
interference of the NOMA signal Thus the security issues are more significant in
this system Here PLS is an available method to rectify the attack intended for
malicious users (Dai et al 2015)
Additionally data should be transmitted confidentially if the root and eavesdropper
networks can be evaluated and the recipient can decrypt the received text At the
same time the eavesdropper is not able to solve the text that has been interrupted
PLS is at the cutting edge of wireless communication security technology to prevent
eavesdropping attacks The SOP is described as the likelihood that the near users
attainable device confidentiality capability will fall under the predefined target
confidentiality rate as set out in (Shim et al 2017)
Through SOP we can calculate the level of protection of the device As an example
the low-secret OP system makes the system more stable in terms of security than
the high SOP system To boost the efficiency of the PLS CSI-based opportunistic
scheduling links to a scheduled destination in a particular time slot It has been
documented as an enticing scheduling scheme (Long Yang et al 2016) because the
various wireless channel has been exploited Opportunistic scheduling is also
considered to be one of the strategies used to increase the confidentiality efficiency
of the NOMA method
322 System Model
Suppose a multi-user NOMA system of downlink containing BS a selection of K
nearer users as N= 119873119894ȁ12 119870 and a range of M far users as F=
119865119895ȁ12 119872 and an eavesdropper E as displayed in Figure 33 More
specifically nearer users should make active use of the SIC methodology to
distinguish far user F Both the legitimate and illegitimate receivers are furnished
through a single antenna and operate in a half-duplex manner
49
Figure 33 Multi-two user architecture of NOMA system (Shim amp An 2018)
Here 119945119935119936 and ȁ119945119935119936ȁ2
Where X120598ሼ119878ሽ 119884120598119873 cup ሼ119864ሽ represent the channel coefficient and the corresponding
channel gain of the X-Y value
Taking into consideration that each wireless channel for Rayleigh block fading 119945119935119936
can be incorporated as an independently distributed random Gaussian variable with
zero mean and affirmative ℷ119935119936 Variance The outcome of channel gain ȁ119945119935119936ȁ2is an
exponential variable randomly through the Probability Density Function (PDF)
119891ȁℎ119883119884ȁ2(119911) = ቀ1
ℷ119883119884ൗ ቁ 119890119909119901 (minus 119911
ℷ119883119884ൗ )
if zge 0 119900119905ℎ119890119903119908119894119904119890119891ȁℎ119883119884ȁ2(119911) = 0 -----------------(1)
Especially the average channel profit can be represented as
ℷ119883119884= ൬119889119883119884
1198890൘ ൰
minus휀
ℒ ------------------(2)
When 120027 is the attenuation of the received signal 119941119935119936 signifies the distance among
X and Y 1199410 indicates the space and 120656 is the exponent of the path loss It is believed
that the source is entirely familiar with the CSI of both legitimate users and
eavesdroppers
50
323 Partially Observable Markov Decision Process-POMDP
Figure 34 Flow Diagram of the proposed system
The proposed overflow is shown in Figure 34 After the BS has been set up the
distance between the BS and the user is calculated and if space is less than 200m
it is defined as a trusted user While if the range is more than 200m it is described
as untrusted users In the event of untrusted users the channel state information is
accessible to the POMDP accompanied by the allocation of resources The study
was carried out after the machine operation Here a NOMA-oriented cellular setup
provided with a BS at the Centre and two users was described in Figure 35
51
Figure 35 Near and Far User
The adjacent user has a high level of security confirmation needed to protect the
layer since the low-security clearance user is situated at a distance away from the
BS P is specified as the highest level of transmitting power In this chapter it is
presumed that all DNS servers are furnished utilizing an individual antenna and all
channels are supposed to be individually static identical to the Rayleigh
dissemination concerning distribution
119862119873(0 120575119898
minus120572
212059601 2Τ
)
In which 120633119950 is the range between the BS and the nodes 119932119950 Here the path-loss
exponent and constant are defined as 120630 and 1206540 Furthermore BS is assumed to
have predicted the position of the user so that a better CSI can be obtained at BS
that is elaborate in user pairing
The BS transmits the superimposed mixture
119909119905 = ඥ1199051199041 + ඥ1 minus 1199051199042 ------------------------------- (3)
In which 1199561 and 1199562 are the unit of power signals received by users 1199321 and 1199322
respectively t is the power allocation coefficient for the adjacent user
1199031 = ℎ1119909119905ξ119875 + 1198991 ------------------------------- (4)
1199032 = ℎ2119909119905ξ119875 + 1198992 ----------------------------------(5)
Where 1199451119886119899119889 1199452 the channel profit link with the fading of small scale since the
BS to the user 1199321 and 1199322 respectively The additional Gaussian noise with variance
52
is denoted 1199511 119886119899119889 1199512 and zero mean 119894119904 119889119890119899119900119905119890119889119886119904 (1199250) and it is assumed
that the BS conveyed SNR is 120646 = 1199271199250
ൗ
In the NOMA technique additional users with more power may decode their signal
by recognizing the adjacent signal as noise without decoding the adjacent user
message In the previous equation 1198801 is supposed to first solve a weak signal by
decoding its own SIC signal1198802 which is an unauthenticated user attempted to
decrypt the nearer user text after decrypting the adjacent usage text after decoding
its own SIC message The following equation has therefore been achieved
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2 ----------------(6)
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2 ----------------(7)
119879119900119905119886119897119904119894119899119903 = 11987811986811987311987721 1198781198681198731198771
1 119878119868119873119877221198781198681198731198771
2 -----------------(8)
Where 119930119920119925119929119950119951
indicates the SINR ratio of user mth that was decoded by 119932119951 for
119898 119899 isin ሼ119894 2ሽ and the channels gain followed an exponential distribution with the
parameter 120649119950=120654120782120633119950minus120630
324 Problem formulation
As a result the BS could achieve and provide better communication for users who
are vulnerable to security threats from unauthenticated users the proposed
framework identified two kinds of QoS energy efficiency that could be considered
essential for addressing the problem In a particular study a pair of OPs was
specified to check the reliability at which the attainable data rate for users is equal
to or greater than the threshold of minimum reach The following issue aimed at
reducing the pair OP to an SOP factor intended for the user 119932120783 that is provided by
Where 1199270is Outage Probability- (OP)
1199271 is Secrecy Outage probability user U1 119930119926119927(119932120783) and
120631 the permissible SOP threshold
53
33 Performance Analysis Improving PLS Insecurity of NOMA
System
331 The Pair OP Calculation
Through Shannons capacity formula and assuming 119914120783119957119945 119886119899119889 119914120784
119957119945 as the
threshold capacities of users 119932120783 119886119899119889 119932120784 respectively the combination of OP
could be offered by
119927119954 = 120783 minus 119928120783119961119928120784 in which 120649119950 = 120784119940119950119957119945
119950 isin ሼ119946 120784ሽ -------------(9)
empty120783 =120649120784
120646(120783+119957+120649120784119957) empty120784 =120649120783
120646119957
119928120783 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ 120782 lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 ------------------------(10)
Case 1empty1 gt empty2 for having the limitation of the allocation of power factor (t)
required to be satisfied (tgt120649120783
120649120783+120649120784+120649120783120649120784) and for this case 119928120784 could be attained as
follows
119928120784 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ
120649120783
120649120783+120649120784+120649120783120649120784lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 --------------(11)
Case 2 empty1 lt empty2 Like case 1 it was stated that the opposite constraint depends
on
t gt 1206491
1206491+1206492+12064911206492 and 1199282 can be evaluated as follows
119928120784 = ൝119942119961119953 ቀ
minusempty120784
120649120783ቁ 120782 lt
120649120783
120649120783+120649120784+120649120783120649120784
120782 119952119957119945119942119955119960119946119956119942 ---------------------(12)
54
Table 31 List of parameters
Parameters Description
N Number of nearer users
M Number of far users
E Eavesdropper
ℎ119909119910 Channel coefficient between 119909119905ℎchannel and 119910119905ℎ users
119889119883119884 The distance among x and y
1198890 Space
120598 An exponent of the path loss
ℒ Attenuation of the received signal
120575119898 the range between the BS and the nodes
1205960 Path loss constant
120572 Path loss exponent
1199041 1199042 Unit of power signals received by users 1198801 and 1198802
T Power allocation factor for the adjacent user
ℎ1119886119899119889ℎ2 Channel coefficient of 1198801 and 1198802with the fading of small
scale
11989911198861198991198891198992 Gaussian noise variance
1198730 Zero mean for Gaussian noise
120588 Signal to noise ratio
119878119868119873119877119898119899
Signal to interference noise ratio of users n and m channels
55
120591119898 Exponential distribution parameters
1198750 Pair of OP
1198781198741198751 119878119874119875(1198801)
120573 The permissible SOP threshold
Table 31 depicts the list of parameters used in the proposed methodology which
are useful for assigning and the values are assigned based on the parameters given
for the experimental evaluation as well This chapter concludes with the basic and
the actual flow of the proposed method to know more about the work in the
simulation process
332 Pseudo-code for the proposed algorithm
Algorithm I
Step 1 Estimate Rayleigh distribution
119862119873(0 120575119898minus120572 2Τ
1205961199001 2Τ
) where
120633119950 is the distance between nodes 119932119950 and the BS
120630 is the path-loss exponent and
120654119952 is the path-loss constant
Step 2 The BS broadcasts the superimposed mixture and input signal as follows
119909119905 = ξ1199051199041 + ξ1 minus 1199051199042
Where 119956120783 and 119956120784 are the unit power signals received by users 119932120783 and 119932120784
respectively 119957 is the Power allocation coefficient for the near user
Step 3 The received signal is as follows
1199031 = ℎ1119909119905ξ119875 + 1198991
1199032 = ℎ2119909119905ξ119875 + 1198992 where
56
119945120783 and 119945120784 are the channel gain associated with the
small-scale fading from the BS to users 119932120783 and 119932120784 respectively
1199511 and 1199512 are the additive white Gaussian noise with zero mean and variance
119925120782
Step 4 the BS transmit signal-to-noise ratio (SNR)
120646 = 119927119925120782
Step 5 Signal-to-Interference-plus-Noise-Ratio (SINR) for the two users 119932120783
decodes the signal of the weak user first then decodes its own signal after using
SIC 119932120784 is an untrusted user and tries to decode the near user message after
decoding its own message using SIC
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588ൗ and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ2ȁ2+1120588ൗ and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2
119879119900119905119886119897119904119894119899119903 = ሼ11987811986811987311987721 1198781198681198731198771
1 11987811986811987311987722 1198781198681198731198771
2ሽ
where 119930119920119925119929119950119951
is the signal-to-interference-plus-noise-ratio (SINR)
of user 119950th decoded by 119932119951 for 119898 119899120598ሼ119894 2ሽ and ȁ119945119950ȁ2 is the
channels gain of 119932119950
Algorithm II
Partially observable Markov decision process
Step 1 Prediction of the maximum capacity of channel with respect to the data rate
119955119943 = 119877(119878119909119863)
S is denoted as states
Let D be the channel characteristics which are considering here as actions
Reward function R
Step 2 The agent receives an observation 119900120598120118which depends on the new state of
the environment 119930prime and on the just taken action 119941 with probability
119926(119952ȁ119956prime 119941)
Step 3 Reward earned at time t is expressed as
57
119903119891119905 = 119877(119878119909119863)119905
Step 4 reward function on belief states
119919 is the belief states over POMDP states
119919119943 is the belief state transition function
119955119943 = 119877(119867119909119863)
Step 5 The reward function is updated based on the belief MDP the agent only
cares about which action will yield the largest expected immediate reward ie the
maximum capacity channel
119861119891 ቀℎ 119889 ℎprimeቁ = 119875119903 (
119900120598120118
ℎprimeȁℎ 119889 119900) 119875119903(119900ȁ119889 ℎ) 119861119891
119875119903(ℎprimeȁℎ 119889 119900) = ቄ1119894119891119905ℎ119890119887119890119897119894119890119891119906119901119889119886119905119890119908119894119905ℎ119886119903119892119906119898119890119899119905119904ℎ 119889 119900119903119890119905119906119903119899119904ℎprime
0119900119905ℎ119890119903119908119894119904119890
119903119891(ℎ 119889) = σ ℎ(119904)119877(119904 119889)119904isin119878
34 SUMMARY
The NOMA-UAV communication framework has been proposed in this research
work and the Physical Layer security aspect has been focused on for optimization
The PLS performance metrics selected are SOP amp Pair OP in the proposed system
model The POMDP framework is general enough to model a variety of real-world
sequential decision-making problems Applications include robot navigation
problems machine maintenance and planning under uncertainty in general Here
we have adopted the User pairing POMDP algorithm for resource allocation in two
users amp multi-user NOMA-UAV communication networks The proposed study has
been evaluated using performance measures by varying distances of trusted amp
untrusted users from the base station as well as for varying SINR conditions The
simulation results and outcomes are discussed in a further chapter
58
CHAPTER 4
RESULT AND DISCUSSION
41 PERFORMANCE MEASURES OF SECURED NOMA-
UAV COMMUNICATION MODEL
Drones or UAV-based communication technology has been thoroughly studied and
adopted by the 3GPP standard UAV systems have been envisaged to form an
integral part of future wireless communication applications due to their dynamic
flexible and flying nature Due to their ability to reach higher altitudes they usually
have dominant LOS channels with the ground nodes This capability can be used to
provide confidentiality to the legitimate receivers against the eavesdroppers This
can be done by deploying UAVs to launch more effective jamming signal attacks
to terrestrial eavesdroppers The conventional cooperative jamming schemes make
an assumption that the locations of terrestrial jammers are fixed which might
compromise the secrecy of the system if the jammers are located far away from the
eavesdroppers and is also not practical as it makes an assumption of perfect CSI of
the jammer to eavesdropper channel
Here in the proposed scenario of the NOMA-UAV communication network two
key PHY layer security metrics SOP amp Pair Outage Probability have been jointly
optimized for a more effective power allocation factor for NOMA cellular
architecture The varying channel characteristics have been analyzed to achieve the
desired SOP with the constrained threshold minimum target secrecy rate for the
two-user scenario POMDP Algorithm iteratively provides the optimized SINR that
has been used to keep trusted users in pair with the untrusted user with minimum
achievable outage probability
The proposed NOMA-UAV System model has been simulated in MATLAB 2019b
version with mainly Communications System Toolbox Optimization Toolbox RF
Toolbox Signal Processing Toolbox Statistics and Machine Learning Toolbox
The simulation has been carried out for two-user pair to achieve desired secrecy
target rate and feasible pairing between trusted user amp untrusted user(eves-dropper)
59
The optimal-outage performance of minimized pair OP subjected to SOP constraint
has been solved by both dynamic programming optimization and POMDP
optimization approaches
The simulation of the proposed framework for the UAV-NOMA communication
network has been carried out and discussed in two parts two user models and a
multi-user model as below mentioned discussion The base station is deployed at
the center of a cell of radius 1000 m There are two users in the system under
consideration The channel between two nodes in the system suffers both the small-
scale fading and path loss effect Small-scale fading follows the exponential
distribution with the mean value 1 The noise signal of all channels has a Gaussian
distribution with 0 mean and variance 1 The path loss exponent α and the path loss
constant PLo are set to 2 and 01 respectively We assume a normalized bandwidth
of 1 Hz The SOP constraint threshold is assumed 01 and the target secrecy rate is
001 The power allocation coefficient is 015 and the BS transmitted SINR is
assumed 15dB for the proposed model As per the NOMA transmission scheme
SINR has been obtained for User 1 amp User 2 both for SIC decoding POMDP
algorithm optimally tunes the SINR value for User 1 amp User 2 that is considered to
select optimal power allocation coefficient for both trusted and untrusted users with
respective SOP of User1
42 Numerical results and Discussion
Table 41 Simulation Parameters
Parameters Values
Untrusted user Distance (d2) 200-1000 (300 700)
BS transmit signal-to-noise ratio (SNR) (120588) in dB 15
Sop constraint constant threshold (β) 01
Power allocation factor (t) 015
Trusted User distance (d1) 2-
60
Cell Radius (rd) 1000 meters
Path loss exponent (α) 2
Path loss constant (PLo) 01
Normalized bandwidth in Hz 1
Target secrecy rate (Rs) 001
No of Bits 100
Pair Outage Probability (P0) 05250
SINR 5319 15305 5162
10247
421 Feasible amp Infeasible pairing of trusted amp Untrusted users
In this section the CSI value broadcasted by Base Station is assumed 15 dB initially
and for varying channel conditions various SINR values of 120646 = minus20 minus10 20 dB
is described with target secrecy rate 0005 and 001 for power allocation coefficient
015 and User 1 distance at 200m is shown in the Figure 41 below
Figure 41 Impact on Sop with increase distance between BS and user U2
61
Varying target secrecy rate threshold from 0005 to 001 the obtained result in
Figure 42 revealed that the 1199321 is a gradually reducing function for the distance of
untrusted user d2 that implies that the increasing value of d2 leads to the
improvement of the SOP of 1198801
Figure42 Impact on Sop with increase distance between BS and user U2
Since the offered constant threshold 120656 in SOP limit1199322 which should be located at
a larger space when compared with a value of threshold to attain the SOP of 1199321
apart from that it is expected the high target secrecy rate maximizes the SOP of 1199321
Here in below figure the power allocation coefficient has been varied from 0 to 1
with threshold value of t and the desired t_sop for feasible pairing
Figure 43 Feasible pairing t Vs pair OP
62
Pair OP in case of rising 1199322 untrusted user in d2 for different BS transfer the SNR
where t= 015 and d1=200mThe infeasible pairing of SOP (1199321) and the OP pair
by the enhanced allocation of the power (t) d1 (200m) d2 (300m) 120646 = 15 dB and
120656 = 0
Figure 44 shows the identical plotting of data by adjusting the unauthenticated
level of the user through converting it to a BS closer distance (d2=300m) Accuracy
is compared and checked with the full spectrum of numerical simulations The
result has shown that the effectiveness is based on a comparative study of the two
consumers of the BS
Figure 44 Infeasible pairing t Vs pair OP
422 The Secrecy Outage Probability amp Pair Outage Probability
Feasible paring in the SOP of pair OP and 1199321 with the improved power allocation
factor t in which d2=700m d1=200m 120646 = 15119889119861 and The result described that
the OP and SOP of the user 1199321 with increased for two various distances of the 1199322
untrusted user The simulation result approves the convex nature 120656 = 0 1of the OP
and the SOP is sequentially decreased depending on t Generally when it enhances
the power owed to the weak user text reduces that develop the ability of 1198802 for
discerning the superior positioned signals therefore enhancing the SOP of 1198801
63
Figure 45 Secrecy outage probability
Figure 46 Pair outage probability
423 SNR versus Strictly Positive Secrecy Rate
Figure 47 proved that the potential for confidentiality is superior to the existing
techniques The proposed application for pre-coding improves the efficiency of the
device The transmission power of the system is the power needed for the
transmission of particular data
64
Figure 47 SNR versus Strictly positive secrecy rate
If there is a growth in the number of users there is a risk of inference in the
transmission of data and thus the reliability of the data rate may be affected Based
on these cases the efficiency of the antenna power to be withheld and occupy the
data determined
424 Power radiated by per MMBs antenna
In the case of multi-users scenario when there are more than two users then the
allocation of an optimized resource block to all users is the key parameter to achieve
desired outage efficiency because strong users require higher SNR for higher data
rates and weak users are allocated minimum threshold SNR for lower data rate
requirements to maintain suitable pairing OP and SOP balance
Figure 48 Power radiated by per MMBs antenna
65
So the POMDP policy optimization has shown better performance over the
dynamic programming approach particularly when more users are active (a greater
number of antennas as in Figure 48 the overall radiated power per BS antenna in
downlink has been considerably reduced
43 CONCLUSION AND SCOPE OF FUTURE WORK
431 Conclusion
Starting with LTE (4G) OFDMA has replaced WCDMA with mobile cellular
communications and will also be used during advanced 5G while Non-Orthogonal
Multiple Access (NOMA) has recently been recognized as a groundbreaking PHY
technology in UAV communication NOMA scheme is used in place to increase the
effective use of small resources such as in UAV communication where the data rate
is very low and critical decision making is of utmost importance
The critical need for UAV communication is a secure PHY layer for mission-
critical applications and as NOMA doesnrsquot promise high security the proposed
research work has been carried out to enhance the insecurities of NOMA-UAV
communication In this proposed research work the probabilities of confidential
outage (SOP) and OP were investigated in the two-user NOMA system Here BS is
required to pair a trusted or permissible user with other untrusted users due to the
unequal distribution of untrusted and trusted users in the cell The SIC is then
applied to the receiver side intended for decoding the message signals The Pair OP
of both users has been analyzed for varying Target Secrecy Rate (Rs) of the trusted
user U1 which provides constraint threshold of the SOP of U1
By varying the distance of Untrusted users from BS the optimal distance and power
allocation factor for the feasible pairing of trusted and untrusted users without
compromising the secrecy outage probability of U1 has been achieved in simulation
results
POMDP has provided the optimal power allocation as a resource allocation
algorithm in the dynamically changing environment of two user NOMA cases
where the distance between BS and untrusted user varies significantly The
performance of secure NOMA-UAV is affected critically by (SOP of User 1) which
66
should be optimally selected to maintain the proposed Pair OP between both users
and the simulation results have supported this optimal outage performance Thus
NOMA-UAV architecture has the potential of providing a secure PHY layer for
mission-critical applications by opting for suitable decision-making resource
algorithm POMDP
431 Scope of Future Work
Furthermore the multiuser scenario with the increased number of Untrusted users
can be analytically verified and simulated in the same direction for NOMA-UAV
communication to improve transmission security and reliability In addition more
adaptive and efficient Resource allocation algorithms for NOMA-UAV networks
with secured performance in real-time applications should be investigated
1
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11
PUBLICATIONS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495449|P a g e
Migration from 4g LTE to Advanced PHY Techniques for
Unmanned Aerial Vehicle (UAV) Communication
Pankaj Patel PHD StudentGujarat Technological UniversityGujarat India
ABSTRACT
UAV (unmanned aerial vehicles) with their high mobility and low cost have found a wide range of applications
during the past few decades Historically UAVs have been primarily used in the military mainly deployed in
hostile territory to reduce pilot losses With continuous cost reduction and device miniaturization small UAVs
are now more easily accessible to the public hence numerous new applications in the civilian and commercial
domains have emerged For the sake of boosting resilience against faults natural disasters and unexpected
traffic the Unmanned Aerial Vehicle (UAV) assisted wireless communication systems can provide a unique
opportunity to cater for such demands in a timely fashion without relying on the overly-engineered cellular
network However for UAV-assisted communication issues of capacity coverage and energy efficiency are
considered of paramount importance Starting with LTE (4G) Orthogonal Frequency Division Multiple Access
(OFDMA) has replaced WCDMA for cellular mobile communications and it will also be employed in advanced
5G yet Non-orthogonal multiple access (NOMA) has been recently recognized as a promising PHY technique
to significantly improve the spectral efficiency of mobile communication networks In this paper we provide an
overview of UAV-aided wireless communications by introducing the basic networking architecture
highlighting the key design considerations as well as the new opportunities to be exploited
Keywords LTE (4G) Non-orthogonal multiple access (NOMA) Unmanned Aerial Vehicle (UAV) Wireless
communication
----------------------------------------------------------------------------------------------------------------------------- ---------
Date Of Submission 26-04-2019 Date Of Acceptance 06-05-2019
----------------------------------------------------------------------------------------------------------------------------- ----------
I INTRODUCTION The use of unmanned aerial vehicles
(UAVs) will grow rapidly in the next decade These
remotely piloted or preprogrammed aircraft are
envisioned for applications in numerous civil
settings including industrial monitoring scientific
data gathering agriculture public safety and search
and rescue Many other applications - presently
unforeseen - will inevitably also arise These
vehicles also known as the unfortunate misnomer of
drones must be integrated into the national
airspace system and into the airspace worldwide A
natural concern in the use of UAV is safety and this
has direct implications for the control and non-
payload communication systems that must be used
to operate it efficiently Similarly navigation and
surveillance functions must be made more reliable
and more accurate Because of these factors many
UAV research development testing and
standardization efforts are underway by
governments industries and academia Despite the
fact that piloted civil aircraft have been flying safely
for decades UAV presents distinct new challenges
in the form of different flight profiles eg low-
elevation flights and more high-dynamic maneuvers
wider required bandwidths eg for video and
different ground site characteristics such as locations
in cluttered areas and lower elevation antennas
In this paper first the evolution of radio
technologies considered in UAV wireless
communication is reviewed in literature survey and
the significant work in the area is highlighted along
with the newest challenges The reminder of this
paper is organized as follows
The promising technology NOMA and its
variants are discussed in section three In Section
four the system model and assumptions are
presented and in section five the comparative
analysis of NOMA with existing popular technology
OFDMA (OMA) is given with simulation
persormance analysis At last the work is concluded
in section five
II LITERATURE SURVEY Drones variously known as unmanned
aerial vehicles (UAVs) unmanned aerial systems
(UAS) or remotely piloted aircraft system (RPAS)
are used in several parts of the world for surveying
and aerial mapping disaster management work
monitoring crop production and infrastructure
activities besides commercial photography and
courier delivery The viability of UAV as a
multipurpose research vehiclehas driven great
RESEARCH ARTICLE OPEN ACCESS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495450|P a g e
interest since recent decades[1] The
basictechnology building blocks responsible for the
current advancesinclude airframes propulsion
systems payloadssafety or protection systems
launch and recovery dataprocessor ground control
station navigation and guidanceand autonomous
flight controllers The following briefsurvey is
focused on the area of navigation guidance
andcontrol of UAVs Various control design for
UAVs has beenproposed ranging from linear to
nonlinear synthesis timeinvariant to parameter
varying and conventional PID tointelligent control
approaches The developed controllershave been
implemented for different aerial platforms
airship(blimp) fixed-wing UAV small scale
helicopteruad-rotors and MAV Wireless
communication systems that include unmanned
aerial vehicles promise to provide cost-effective
wireless connectivity for devices without
infrastructure coverage Compared to terrestrial
communications or those based on high-altitude
platforms on-demand wireless systems with low-
altitude UAVs are in general faster to deploy more
flexibly reconfigured and likely to have better
communication channels due to the presence of
short-range line-of-sight links However the
utilization of highly mobile and energy-constrained
UAVs for wireless communications also introduces
many new challenges In India for the regulation
and safety purpose in commercial and survilence
applications the policy guideliens also introduced
as below
Table 1UAV communication Policy Guidelines for
commercial and surveillance purpose
III MIGRATION FROM 4G LTE TO 5G The fruitful deployment of UAV based
communicationsystems for 4G and beyond future
wireless networks is highlyinvolved in finding joint
solutions to challenge of ubiquitousconnectivity with
both a multitude of devices in a spectralefficient way
as well as with energy-efficient transmissionand
operation of the UAV-BS for maximized and
armonizedcoverage and capacity [2][3] It should be
noted that suitableenergy efficiency for the UAV-
assisted ommunication systemachieves paramount
importance in the overall performance ofthe system
Efficient energy consumption results in
enhancedairtime for the communication system
improving bitsJoulesfor a given energy level
Furthermore coverage and capacityof an aerial cell
are attributed to many factors such as
thetransmission power antenna gains UAV
altitude deploymentenvironment and prominently
radio access technology [4]
4G is the fourth generation of broadband
cellular network technology succeeding 3G and
besides the popular techniques in 3G4G ie
TDMAWCDMAOFDMA a new radio access
technology NOMA is also developed by researchers
to be used in communication networks due to its
capability in increasing the system capacity
Recently non-orthogonality based system designs
are developed to be used in communication
networks and have gained significant attention of
researchers Hence multiple access (MA) techniques
can now be fundamentally categorized as orthogonal
multiple access (OMA) and non-orthogonal
multiple access (NOMA) In OMA each user can
exploit orthogonalcommunication resources either
within a specific time slot frequency band or code in
order to avoid multiple access interference The
previous generations of networks have employed
OMA schemes such as frequency division multiple
access (FDMA) of first generation (1G)time
division multiple access (TDMA) of 2G code
division multiple access (CDMA) of 3G and
orthogonal frequency division multiple access
(OFDMA) of 4G
In NOMA multiple userscan utilize non-
orthogonal resources concurrently by yielding a high
spectral efficiency while allowing some degree of
multiple access interference at receivers Recently
NOMA reputations have climbedsharply as a
fundamental solution to the challenges
encompassingthe next generation wireless networks
[5][6]NOMA has been proved to exhibit improved
spectral efficiencybalanced and air access as
compared to OMAtechnologies[6] with the ability
to cater for multipledevices in the same frequency
time or code resource thusproviding efficient access
to massive connected devices Furthermore NOMA
is also instrumental in reducingthe interference by
employing orthogonal resources as inOrthogonal
Frequency Division Multiple Access
(OFDMA)[7][17] or by sharing a single beam
between multiple users forintra-cluster access and
using NOMA for inter-cluster access[18]Current
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495451|P a g e
studies have focused on provisioning Air to
Ground(A2G) communication services mainly
through placement op- timization under various
viewpoints in literature The performance of UAV
based communication systems hasalso been
addressed for the underlaid Device to Device(D2D)
deployment scenario This work assumed
interferenceraised by D2D network nodes without
considering the presenceof terrestrial BS
Additionally there have been a fewstudies
discussing the performance of NOMA for UAV
basedcommunication system[8] A NOMA enabled
fixedwingUAV deployment was proposed in [8] to
support coveragefor ground users situated outside
BS offloaded location
In general NOMA schemes can be
classified into two types power-domain
multiplexing andcode-domain multiplexing In
power-domain multiplexing different users are
allocated[7][8][9][6][5][1][10] differentpower
coefficients according to their channel conditions in
order to achieve a high systemperformance In
particular multiple usersrsquo information signals are
superimposed at the transmitterside At the receiver
side successive interference cancellation (SIC) is
applied for decoding thesignals one by one until the
desired userrsquos signal is obtained providing a good
trade-offbetween the throughput of the system and
the user fairness In code-domain multiplexing
different users are allocated different codes and
multiplexed over the same time-frequencyresources
such as multi-user shared access (MUSA) sparse
code multiple access (SCMA) and low-density
spreading (LDS) In addition to power-domain
multiplexing and codedomain multiplexing there are
other NOMA schemes such as pattern division
multiple access(PDMA) and bit division
multiplexing (BDM) Although code-domain
multiplexinghas a potential to enhance spectral
efficiency it requires a high transmission bandwidth
andis not easily applicable to the current systems
On the other hand power-domain multiplexinghas a
simple implementation as considerable changes are
not required on the existing networksAlso it does
not require additional bandwidth in order to improve
spectral efficiency Inthis paper the prime focusis on
the power-domain NOMAAlthough OMA
techniques can achieve a good system performance
even with simple receiversbecause of no mutual
interference among users in an ideal setting they
still do not have theability to address the emerging
challenges due to the increasing demands in future
networks andbeyond
The superiority of NOMA over OMA can
besummarized as follows
_ Spectral efficiency and throughput In OMA such
as in OFDMA a specific frequencyresource is
assigned to each user even it experiences a good or
bad channel conditionthus the overall system suffers
from low spectral efficiency and throughput In
contrary inNOMA the same frequency resource is
assigned to multiple mobile users with good and
bad channel conditions at the same time Hence the
resource assigned for the weak user isalso used by
the strong user and the interference can be mitigated
through SIC processesat usersrsquo receivers Therefore
the probability of having improved spectral
efficiency and ahigh throughput will be considerably
increased
_ User fairness low latency and massive
connectivity In OMA for example in OFDMAwith
scheduling the user with a good channel condition
has a higher priority to be servedwhile the user with
a bad channel condition has to wait to access which
leads to a fairnessproblem and high latency This
approach cannot support massive connectivity
HoweverNOMA can serve multiple users with
different channel conditions simultaneously
thereforeit can provide improved user fairness lower
latency and higher massive connectivity
_ Compatibility NOMA is also compatible
with the current and future communication
systemssince it does not require significant
modifications on the existing architecture For
exampleNOMA has been included in third
generation partnership project long-term
evolutionadvanced (3GPP LTE Release 13)
Figure 1Pictorial comparison of NOMA Vs OMA
Although NOMA has many features that
may support next generationsit has some limitations
that should be addressed in order to exploit its full
advantage set Thoselimitations can be pointed out
as follows In NOMA since each user requires to
decode thesignals of some users before decoding its
own signal the receiver computational
complexitywill be increased when compared to
OMA leading to a longer delay Moreover
informationof channel gains of all users should be
fed back to the base station (BS) but this results in
asignificant channel state information (CSI)
feedback overhead Furthermore if any errors
occurduring SIC processes at any user then the error
probability of successive decoding will beincreased
As a result the number of users should be reduced to
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495452|P a g e
avoid such error propagationAnother reason for
restricting the number of users is that considerable
channel gain differencesamong users with different
channel conditions are needed to have a better
network performance
IV NOMA UPLINK AND DOWNLINK
SCENERIO SIMULATION ANALYSIS In this section an overview of NOMA in
downlink and uplink networks is introduced
throughsignal-to-interference-and-noise ratio (SINR)
and sum rate analyses Then high signal-to-
noiseratio (SNR) analysis has been conducted in
order to compare the performances of OMA
andNOMA techniques[10]
A Downlink NOMA Network
At the transmitter side of downlink NOMA
network as shown in Fig 2 the BS transmits
thecombined signal which is a superposition of the
desired signals of multiple users with different
allocated power coefficients to all mobile users At
the receiver of each user SIC process isassumed to
be performed successively until userrsquos signal is
recovered Power coefficients ofusers are allocated
according to their channel conditions in an inversely
proportional mannerThe user with a bad channel
condition is allocated higher transmission power
than the one which has a good channel condition
Thus since the user with the highest transmission
power considers the signals of other users as noise
and recovers its signal immediately without
performing anySIC process However other users
need to perform SIC processes In SIC each userrsquos
receiverfirst detects the signals that are stronger than
its own desired signal Next those signals
aresubtracted from the received signal and this
process continues until the related userrsquos own signal
is determined Finally each user decodes its own
signal by treating other users with lower
powercoefficients as noise The transmitted signal at
the BS can be written as
s = aiPsxi
L
i=1
where xi is the information of user i (Ui)
with unit energy Ps is the transmission power atthe
BS and ai is the power coefficient allocated for user
i subjected to ai = 1Li=1 and a1gea2gehellip geaL since
without loss of generality the channel gains are
assumed to be ordered as h1 2 le h2 2 le⋯ hL 2 where hL is the channel coefficient of Lth
user based on NOMAconcept The received signal
at lth user can be expressed as follows
y1 = hls + nl = hl aiPsxi + nlL
i=1
where nlis zero mean complex additive Gaussian
noise with a variance of σ2
(1) SINR analysis By using (2) the instantaneous
SINR of the lth user to detect the jth user jle l
with jne L can be written as
SINRl = alγ hl 2
γ hl 2 aiLi=l+1 + 1
Where γ = Psσ2 denotes the SNR
(2) Sum rate analysis After finding the SINR
expressions of downlink NOMA the sumrate
analysis can easily be done The downlink
NOMA achievable data rate of lth user can
beexpressed as
RlNOMA-d
= log2 1 + SINRl = log2(1 +alγhl2γhl2 i=l+1Lai+1
B Uplink NOMA Network
In uplink NOMA network as depicted in
Fig 3 each mobile user transmits its signal to the
BS At the BS SIC iterations are carried out in order
to detect the signals of mobile users By assuming
that downlink and uplink channels are reciprocal and
the BS transmits power allocation coefficients to
mobile users the received signal at the BS for
synchronous uplink NOMA can be expressed as
r = hi aiPxi + n
L
i=1
where hi is the channel coefficient of the ith
user Pxi is the maximum transmission power
assumed to be common for all users and n is zero
mean complex additive Gaussian noise with a
variance of σ2
Figure 2Downlink NOMA network
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495453|P a g e
Figure 3 Uplink NOMA network
1) SINR analysis The BS decodes the signals of
users orderly according to power coefficientsof
users and then the SINR for lth user l ne 1 can
be given by
SINRl =alγ hl 2
γ ai hi 2 + 1lminus1i=1
where γ =P
σ2
2) Sum rate analysis The sum rate of uplink
NOMA when γ minus infincan be written as
Rsum NOMA-u asymp log2(γ hl 2L
l=1
C Comparing NOMA and OMA
The achievable data rate of the lth user of OMA for
both uplink and downlink can be expressed
RsumOMA = αl log2(1 +
βlγ hl 2
αl)L
l=1
For the sake of simplicity sum rates of
uplink NOMA and OMA can be compared for
twousers Then using both the sum rate of uplink
NOMA and OMA at high SNR can beexpressed
respectively as
RsumNOMAasymp log2 γ h1 2 + γ h2 2
Here we notice ROMA
sumle RNOMA
sum
Fig shows that NOMA outperforms OMA in terms
of sum rate in both downlink and uplinkof two
user networks
V SIMULATION RESULTS
The Comparative analysis of modelling
Downlink and Uplink NOMA in comparison with
OMA is simulated and findings are presented that
shows superiority of NOMA over OMA with better
spectral efficiency for simulation parameters taken
as power allocation coefficients a1=06 a2=04 and
channel responses h1 2
=0 DB h22=20 DB
parameters
Figure 4NOMA UPLINK
Figure 5 NOMA DOWNLINK
VI CONCLUSION This paper investigated an account of
NOMArsquos applicability for UAV-assisted
communication systems NOMA schemes are
proposed to improve the efficient usage of limited
network sources OMA based approaches that use
time frequency or code domain in an orthogonal
manner cannot effectively utilize radio resources
limiting the number of users that can be served
simultaneously In order to overcome such
drawbacks and to increase the multiple access
efficiency NOMA technique has been recently
proposed Accordingly users are separated in the
power domain Such a power domain based multiple
access scheme provides effective throughput
improvements depending on the channel conditions
The crucial need of UAV communication of
optimum utilization of available licensed spectrum
bandwidth is considered here and simulation results
taken presented that NOMA performs better than
OMA while fulfilling individual user-rate constraint
for both users The research work can be further
carried out investigating joint power and phase
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495454|P a g e
allocation of UAV nodes deployment for efficient
operations
REFERENCES [1] S M I C Y L M I Muhammad Farhan Sohail
Non-Orthogonal Multiple Access for Unmanned
Aerial Vehicle Assisted Communication in IEEE
access 2018
[2] M Mozaffari Drone small cells in the clouds
Design deployment and performance analysis in
IEEE Global Communications Conference 2015
[3] R Z a T J L Y Zeng Wireless
communications with unmanned aerial vehicles
opportunities and challenges in IEEE
communication magazine 2016
[4] I B-Y a H Yanikomeroglu The new frontier in
ran heterogeneity Multi-tier drone-cells IEEE
Communications Magazine pp 48-55 2016
[5] P K S a D I Kim Uav-enabled downlink
wireless system with NOMA access in IEEE
Globecom Workshops Dec 2017
[6] P Xu and K Cumanan Optimal power allocation
scheme for nonorthogonal multiple access with
fairness in IEEE Journal on Selected Areas in
Communications oct 2017
[7] E H a D I K S Ali Non-orthogonal multiple
access (noma) for downlink multiuser mimo
systems User clustering beamforming and power
allocation in IEEE Access 2017
[8] W S M B a M D M Mozaffari Unmanned
aerial vehicle with underlaid device-to-device
communications Performance tradeoffs in IEEE
Transactions on Wireless Communications June
2016
[9] Z D X D a R Z Z Chen An optimization
perspective of the superiority of noma compared to
conventional oma in IEEE Transactions on
Signal Processing Oct 2017
[10] M T Mahmoud Aldababsa1 and S G G K 2 A
Tutorial on Non-Orthogonal Multiple Access
2017
[11] X L Z J W a K J R L Zhu Han Delay
Sensitive Scheduling Schemes for Heterogeneous
QoS over Wireless Networks IEEE
TRANSACTIONS ON WIRELESS
COMMUNICATIONS VOL 6 NO 2
FEBRUARY 2007 vol 6 no 2 2007
[12] Z J W a K J R L Z Han A resource
allocation framework with credit system and user
autonomy over heterogeneous wireless networks
in IEEE Global Telecommunications Conference
2003
[13] N B S a P S S Chen Heterogeneous delay
tolerant task scheduling and energy management in
the smart grid with renewable energy IEEE
Journal of Selected Areas in Communications vol
31 no 07 pp 1258-1267 july 2013
[14] H L Z C a Z H Y Hu Scheduling strategy for
multimedia IEEE Transactions on Vehicular
Technology July 2016
[15] P F a K B L Y Dong High-speed railway
wireless communications efficiency vs fairness
IEEE Transactions on Vehicular Technology vol
63 no 2 pp 925-930 march 2014
[16] T R a Z H Z Chang Queueing game for
spectrum access in cognitive radio networks
IEEE Communications Letters vol 19 no 11 pp
2017-2020 June 2015
[17] Z C L T R a Z H F I Yun Hu Service
Provisioning and User Association for
Heterogeneous Wireless Railway Networks IEEE
Transactions on Communications 2017
[18] H S W Tianti Chen Optimal Scheduling for
Wireless On-Demand Data Packet Delivery to
High-Speed Trains IEEE Transactions on
Vehicular Technology vol 64 no 9 pp 4101 -
4112 september 2015
Pankaj Patel Migration from 4g LTE to Advanced PHY Techniques for Unmanned Aerial
Vehicle Communication International Journal of Engineering Research and Applications
(IJERA) Vol 09 No04 2019 pp 49-54
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Improving Of Physical Layer Insecurity Of The
Non Orthogonal Multiple Access System
Pankaj M Patel Prof Dr Chetan B Bhatt
Abstract The key aspect of the NOMA (power domain non orthogonal) is the user possibility for decoding the messages belonging to another pair users
on similar resources The method interprets a security threat especially in the case where the base station serves the users with various security
clearance or untrusted users The main aspect of NOMA is to serve the multiple users upon the similar radio resources at the minimal inter user
interference expense The system not only permits the serving of particular users with high efficient bandwidth but also permits the scheduling more type
of users than the timely available users In this study we investigated the secrecy outage probability (SOP) and OP in the both two user and multi user
NOMA system where the BS is supposed to pair a trusted or legitimate user with other untrusted users because of the un even distribution of the
untrusted and trusted users in the cell SIC the successive interference cancellation was then implemented at the receiver side for decoding the
message signals With the application of NOMA concept the study investigated the pair outage behavior under the SOP constraints on the trusted users
In specific the SOP and OP of the concerned U1 were obtained in the closed type of expressions The study also provided the understanding the
possibility of obtaining an optimal outage efficiency for pairing under the SOP constraints With certain numerical simulations the study verified the
effectiveness of the analytical derivations with respect to various scenarios
Index Terms NOMA Secrecy outage Probability Successive Interference Cancellation bandwidth channel state information etc
mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash
1 INTRODUCTION The physical layer security and non-orthogonal multiple
access was regarded as the encouraging techniques for the
processing of wireless communication network systems Today
the combination of the two significant communication methods
was studied to guarantee a spectral efficient and secure
wireless transmission Most of the prevailing works
predominantly concentrated on the optimization and efficiency
of the PLS in the existence of untrusted relay nodes and
external eavesdroppers(Arafa et al 2019a)But there occurs a
gap in the theoretical studies to describe the ease of obtaining
the enhanced efficiency in the existence of untrusted users
Recently the network traffic amount have greatly enhanced
particularly with the updated growth in IoT applications in
future To rectify the huge traffic demand upcoming wireless
networks must deliver a best spectral effectiveness and large
connectivity (Sun et al 2018) NOMA is regarded as the best
technology in which various NOMA technique exhibit similar
concept of providing several users at the similar frequency and
time The famous NOMA types are code domain and power
domain that provided enhanced efficiency when compared
with the existing techniques The paper adopted the power
domain on the basis of super position coding (transmitter side)
at the SIC (receiver side) Hence the users could possess the
key for the messages of other users and thereby utilize SIC for
removing the interference (Cao et al 2019) (Zhao et al
2018) Hence various NOMA methods was proposed for
allowing the adjacent users to perform as a relay for improving
the efficiency of the weak users through the resending of
decoded data in a next time slot The weak user could utilize
the MRC technique to integrate the information achieved in
different time slots In addition obtaining a secured
communication is a crucial problem over the vulnerable
wireless networks to security threats mainly because of the
broadcasted transmission nature
The study investigated the secrecy performance and outage
with the untrusted user(Furqan et al 2019) The main aspect
of the study is to analyze the feasibility of achieving the OP of
the pair under a trusted user Because of the decoding facility
and spectrum sharing of SIC the untrusted user could perform
as a eavesdropper
Figure 1 Representation of Base station
Figure 1 depicts the representation of base station The main
aim of the proposed system defined as
bull To investigate the outage probability of the proposed
system
bull To investigate the SOP of the proposed system
bull To derive the accurate expression of the outage
probability for all kind of scenarios and closed form of
expressions for few special cases and verifying them
numerically for yielding a better outage efficiency
2 RELATED WORKS This section describes the different existing techniques and
methods related as our proposed system (Cao et al
2019)suggested two kinds of relay selection process denoted
as AF (amplify and forward) and DF (decode and forward) on
the basis of AORS and DORS for achieving secure and
reliable NOMA systems under the untrusted users The study
derived the accurate and asymptotic closed form of the SOP
expressions and the PSCP obtained by the two methods and
investigated the optimized feature of the two methods The
____________________________________
bull PANKAJ M PATEL is currently pursuing PHD program in Electronics
amp Communication in Gujarat Technological University E-mail
pankajmphd24gmailcom
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complete analysis and the simulation results represented that
both the AORS and DORS characteristically outperformed the
benchmark system apart from obtaining the similar SOP and
the required PSCP at very high Signal to noise ratio (Zhang et
al 2018)Investigated the power allocation and joint subcarrier
issue for NOMA ndashAF two-way relay networks with restrictions
The study focused to optimize the obtainable secrecy
efficiency by designing jointly the SC task power allocation
and user pair scheduling The paper suggested a SCAS-1
technique by assuming the appropriate information about the
channel state information in the relay station followed by the
formulation of SCAS-2The secured power allocation issue is
structured as a convex programming issue and then resolved
by in-depth point techniques The results of simulation
explained that the efficiency of the suggested SSPA algorithms
with and without CJ respectively (Arafa et al
2019b)Considered a downlink system where the base station
is connecting with two appropriate users in two various
scenarios in the unsecured environments which are the
presence of the eavesdropper and untrusted relay
communication In the first process several trusted
cooperative relays is engaged for assisting with the base
station transmission and protect the corresponding signals
from the eavesdropper Several relay methods are framed and
investigated for the following process which are forward and
decode cooperative jamming and AFFor all the technique
secured beam forming signals were formulated at the relays
for maximizing the obtainable secret rate areas For the next
process with untrusted relay the obtained secrecy rate areas
obtained for two various relay schemes which are AF and CF
under two various operation modes In the first process the
prescribed users will receive the signals from the untrusted
relay and the base station for decoding the messages The
study depicted that the efficient relay scheme is highly
dependent on the parameters of the system especially the
nodal distance and the secrecy rate area (Sun et al
2018)Studied the algorithm for resource allocation for MISO
systems where the full duplex BS serve several half duplex
downlink and uplink users on the similar subcarrier The
allocation of the resource have been optimized for maximizing
the weight system output whereas the leakage of information
was restricted and an artificial noise was induced for granting
secured communication with respect to potential
eavesdroppers The study formulated a novel non-convex
optimization issue by considering the imperfect CSI of the
channels and requirements of QoS of legitimate users The
simulation results stated the efficiency of the optimal algorithm
was related to the suboptimal algorithm Apart from that the
suggested MISO NOMA technique not only guarantee uplink
and downlink communication purpose for security but delivers
a characteristic rate of system secrecy when compared with
the conventional MISO and other two baseline methods
(Dang et al 2017)Analysed the outage efficiency of various
multicarrier relay selection techniques for 2 hop OFDM system
in Poisson relay fields The study concentrated on DF relay
systems with more selection schemes The accurate
expressions for the OP are provided in integrals generally
Apart from that asymptomatic derivatives for OP in the SNR
region in the fixed circle area are predicted for both relay
selection techniques in closed forms Consequently several
significant factors that are linked to the cooperative network
were examined comprising OP ratio of two selection
techniques diversity and subcarrier optimization output In
conclusion a structure to analyze the OP of OFDM with
spatially random relay have been constructed that could be
easily altered for analyzing same case with various forwarding
protocols channel conditions and location distributors (Dang
et al 2018)Proposed a full duplex OFDM ndashD2D system in two
hop network where DF relays help the transmission from DUE
transmitter to DUE receiver The study also investigated the
OP issue by integrating the transmit power within the DUE
relays and transmitter and to deliver a suboptimal solution that
can improve the outage performance The investigations are
validated by Monte Carlo simulations These results described
could furnish an insight into full duplex OFDM system and
guides for the application in the next generation network
(Kokshoorn et al 2016) suggested a robust channel algorithm
for mmWave systems on the basis of novel overlapped pattern
design With the use of finite measurements the study
depicted that this decreased measurements was found ENR of
25 dB to obtain the similar PEEFor the appropriate channel
with quickly altering channel information the price might be
acceptable for improving the speed of estimation The study
also proposed a robust channel estimation algorithm where
the additional calculations are carried out when expecting
more estimation error The study depicted that the channel
could be measured more effectively resulting in noteworthy
gains upto 6 dB when comparing with the existing algorithm
(Ali et al 2016) described the variations in the principles of
downlink and uplink NOMA transmissions in a wireless
system The study formulated a maximization issue in a cell
like the user clustering and power allocations Because of the
integral nature of the formulated programming issue the study
solved the issue in to steps which are grouping of users into
clusters and then to optimize the corresponding power
allocations The study proposed a sub optimal scheme that
exploited the gain variations in NOMA groups and clusters into
multiple and single clusters for enhancing the sum-throughput
The results compared the efficiency of OMA and NOMA in
different network scenarios (Lv et al 2017) investigated a
MCR-NOMA where the multicast user functions as relays to
enhance the efficiency of both secondary and primary
networks On the basis of the available CSI three various
secondary user schedule techniques for processing MCR-
NOMA were depicted For evaluating the system efficiency the
study derived the closed form of expressions of OP and order
of diversity for both the networks It has been described that
more spatial temporal diversity could be obtained by using the
CSI for scheduling of the secondary user (Liu et al 2016)
considered a MIMO ndashNOMA scenario for investigating a
dynamic clustering issue in an logical perspective To resolve
the problem of optimization issue three algorithms named top
down A and B bottom up were suggested for realizing various
complexity tradeoff and worst user throughput The study
noted that the top down B algorithm could obtain a better
tradeoff between throughput and complexity amongst the
applied procedures (Fianu and Davis 2018) investigated
three various rules of allocation and demonstrated the optimal
policy as an available inventory function The study also
provided the country level estimation of requirements that are
not met and the determination of the probability distribution
linked with the total undeserved counties The study have
been done for depicting the policy of allocation with respect to
effectiveness and equity (Hou et al 2018) studied the socio
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graphical impact on the mobile video services and thereby
suggested a CTMDP on the basis of resource allocation
technique by considering social graphs as the constraints
With the use of relative value an optimized policy could be
achieved that aimed at increasing the reward regarding the
average system The simulation depicted that the suggested
CTMDP obtained an increased efficiency against the state of
art methods
3 PROPOSED WORK
Fig 2 Proposed flow depicting the overall mechanism
The proposed(Interference mitigation using POMDP) overall flow
is depicted in the figure 2 After setting up of the base station the
distance between the base station and the user was determined
and if the distance is less than 200 meters it is decided as trusted
users and if it is greater than 200 m it is defined as untrusted
users In case of untrusted users the channel state information is
subjected to POMDP (Partially observable Markov Decision
Process) followed by resource allocation The performance
analysis have been done after the system The work considered
a NOMA oriented cellular setup provided with a base station at
the centre and two users as shown in the figure 2 The adjacent
(near) user possess high level of security clearance that is
required for securing with physical layer from the low
securityuntrusted clearance user (U2) that is located at a faraway
distance from the base station P is defined as the maximum
transmit power level (base station)In this paper it is assumed that
all the network nodes are installed with single antenna and further
all the channels are considered to be identical independently
quasi static with Rayleigh distribution with respect to distribution
119862119873(0 120575 frasl
120596 frasl
) In which 120575 is the distance in-between the BS
and nodes 119880 Here path-loss exponent and path-loss constant is
represented as 120572 and 120596 In addition it is assumed that base
station predicted the user location so that a better CSI is
obtainable at base station that is involved in pairing the users
The base station transmits the superimposed mixture
119909 = radic119905 119904 + radic1 minus 119905 119904
In which 119904 119904 are the unit power signals received by users 119880 and
119880 respectively 119905 is the power
allocation coefficient for the adjacent user
119903 = ℎ 119909 radic119875 + 119899
119903 = ℎ 119909 radic119875 + 119899
where ℎ ℎ - the channel gain linked with the
small-scale fading from the base station to users 119880 and 119880
respectively 119899 and 119899 are the extra white Gaussian noise with
variance and zero mean 1198730 and it is assumed that 120588 = 1198751198730 is
the BS convey signal-to-noise ratio (SNR) In NOMA technique
farther user that possess more power
could decode its own signal by considering the adjacent signal as
a noise without decoding the adjacent user message In the
preceding equation it is assumed that U1 first decode the weak
signal followed by decoding its own signal with SICU2 which is
the untrusted user attempted to decode the near user message
after the decoding of the adjacent user messages after the
process of decoding its own message with SICHence the
following equation have been achieved
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119879119900119905119886119897 = 119878119868119873119877 119878119868119873119877
119878119868119873119877 119878119868119873119877
+
where 119878119868119873119877 represented the signal-to-interference-plus-noise-
ratio of user 119898 that was decoded by 119880 for 119898119899120598119894 2+ and the
channels gain of 119880 denoted by |ℎ |
followed an exponential distribution
with the parameter 120577 = 120596 120575
Problem Formulation
Hence the base station should achieve and serve a better
communication for the users who are susceptible to security
threat from untrusted user the proposed system defined two
kinds of QoS efficiency measures that could be regarded to be
important for framing the issue In specific the study defined a pair
of OP to check the reliability of the QoS satisfaction In general
the pair OP is stated as the probability in which the obtainable
data rates dor the users equal to or greater than the least target
threshold The next metric also called as the SOP is the
probability that the non negative secrecy capacity obtained by the
trusted user is more than the threshold value
The following issue aimed at reducing the pair OP subjected to a
SOP factor for the user U1 that is provided by
min
119875
0 lt 119905 lt 05
119878119874119875 le 120573
in which 119875 119878119874119875 and 120573 are the pair OP SOP(119880 ) and the
permissible SOP threshold
4 PERFORMANCE ANALYSIS
Derivation of the Pair OP
With the use of Shannonrsquos capacity formula and considering
119862 and 119862
as the threshold capacities of users 119880 and
user 119880 respectively the OP of the pair could be provided
by
119875 = 1 minus 119876 119909119876
in which
120591 = 2
119898 120598 119894 2+
120601 =
( )
120601 =
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119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 1 120601 gt 120601
For having 120601 gt 120601 the constraint on
the power allocation factor (t) needs to be satisfied
(119905 gt
) and for this case 119876 could be obtained as
follows
119876 = exp (
)
lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 2 120601 lt 120601
Like case 1 it was stated that opposite constraint on
a as (119905 lt
) and
119876 can be derived as follows
119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
The OP of the NOMA pair
119875 = 1 minus 119891(119905)119896 (119905)
lt 119905 lt
1 minus 119891(119905)119896 (119905) 0 lt 119905 lt
in which
119891(119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
Derivation of SOP of 119880
With Shannonrsquos capacity formula the secrecy rate of
user 119880 was provided by
119878119862 = 119869 minus 119869
119869 = log (1 + 119879119900119905119886119897 (r (1)))
119869 = log (1 + 119879119900119905119886119897 (r (2)))
119878119862 is the non-negative secrecy capacity of 119880 Provided the
secrecy capacity in the SOP of 119880 is
119878119874119875 = 1 minus 120584119890
119860 =
120584 =
119879 - the user 119880 secrecy target rate
Theorem 1
Outage-optimal power allocation factor
119905 = radic
( )
In which 119908 =
119908 =
119911 = 1 + 120591
The minimum power allocation factor (119886 )
119905 =
(
)
The optimal OP of the NOMA pair under the SOP constraint
=
( )
( ( ))119890
( )
That is lt 0whih meant that the U1 (SOP) is a reducing function
Of t that results in the optimal power allocation factor that is
greater than 119905 for the satisfaction of secrecy constraining
factorPartially observable Markov decision process S is
represented as statesLet D is the channel features which is
consider here as actions the conditional transition probability
between states is regarded as T Reward function R is
calculated as the prediction of maximum capacity channel with
respect to data rate r = R(S x D) the agent receives an
observation o ϵ 120118 o isin Ω display style oin Omega that
depended on the new environment state S and on the just
took action d with the probability O(o|s d)
Reward received at time t is conveyed as r = R(S x D)
H is the belief states over POMDP states
119867 is the belief state transition function
119903 = 119877(119867 x 119863) is the reward function on the belief states
119861 (ℎ 119889 ℎ ) = sum Pr ( 120118 ℎ |ℎ 119889 119900) Pr(119900|119889 ℎ)
Pr(h |h d o) =
1 if the belief update with arguments h d o returns h 0 otherwise
The reward function is updated on the basis of the belief MDP
r (h d) = sum h(s) R(s d) isin
the agent focus on the largest expected immediate rewardin
other words the maximum capacity channel The section
analyse the accuracy of the analytical derivations under
various settings
Figure 3 The feasible pairing
The SOP of U1 with the increasing untrusted user U2 and
distance (d2) for several BS transmits Signal to Noise Ratio
at 120588 = minus20minus1020 119889119861is depicted in with a=005 and 01 and
d1=200m is depicted in the figure The results stated that the
U1(SOP) is a gradually reducing function as per d2 that
implies that the increasing value of d2 leads to the
improvement of the SOP of U1 Since the provided constant
threshold ϵ in SOP restraint U2must be situated at a larger
space when compared with threshold value to obtain the SOP
of U1 Apart from that it is normal that the high the target
secrecy rate rises the SOP of U1
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Figure 4 The Secrecy outage probability
Feasible Pairing in th SOP of pair OP and U1 with the
enhanced power allocation factor (a) in which d2 = 700 m d1
= 200 m 120588 = 15 dB and ϵ = 01 The results depicted that the
the pair OP and SOP of user U1 with increased a for two (d2)
various distances of the (U2) untrusted user The results
approve the convex nature of the pair OP and the SOP curve
is gradually decreasing on the basis of a Generally during the
increase in a the power assigned to the weak user message
decreases that minimize the ability of U2 for discriminating the
superior positioned signals thereby improving the SOP of U1
Figure 5 The Pair outage probability
Pair OP in case of rising U2 untrusted user in distance (d2)
for different base station transfer the signal to noise ratio(120588 =
5 15 25 dB) where a = 015 and d1 = 200 m
Figure 6The infeasible pairing of secrecy outage
probability of the pair OP and U1
The infeasible pairing of SOP (U1) and the pair outage
probability with the enhanced allocation of the power ad1(200
m)d2(300 m)120588 = 15dB and ϵ = 0
The figure 6 depicted that the
The figure 6 shows the similar plotting of the data by altering
the untrusted user location by transferring it to a BS closer
distance (d2 = 300 m) It also depicted that the U1 SOP
constraint of is disrupted at a because the SOP is more than ϵ
The accuracy is well-matched and verified with all range of
numerical simulation The results noticed that the efficiency is
based on the comparative locations of the two user with the
base station
Figure 7 The figure 7 depicts that SNR versus strictly
positive secrecy rate
The observed graph proves that the secrecy capacity
outperforms the existing techniques The proposed precoding
application increases the performance of the system The
transmission power of the system is the power required to
transmit a particular data When there is an increase in the
number of users there is the possibility of inference in the data
transmission and hence the efficiency of the data rate may be
affected Depending on these instances the efficiency of the
antenna capacity to withheld and accommodate the data
determined
Figure 8 The power radiated by BS antenna
In the figure 8with respect to the simulation setup the
precoding methods are performed based on the radiated
power per BS antenna is depicted The results observed the
better efficiency of the proposed system The proposed proves
to be better when compared with existing linear precoding
methods in the prescribed three metrics thereby stating that
MRT may be utilized for the the examination of the secrecy
capacity Our proposed technique spends less radiatated
power thereby increasing the overall capacity of the system
5 CONCLUSION The NOMA system decodes the messages of other user pairs
on the similar resources thereby promoting user possibility
The technique interprests a security threat in which the BS
serves the untrusted users The study analysed the SOP and
OP in both multi user and two user NOMA system in which the
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base station pairs the trusted user in closed type of
expressions The proposed (Interference mitigation using
POMDP) also enable the understanding of possibility of
achieving outage optimal efficiency to pair under SOP
constraints The numerical verifications verified the efficiency
of the analytical derivations
6 REFERENCES [1] ALI M S TABASSUM H amp HOSSAIN E 2016
Dynamic user clustering and power allocation for
uplink and downlink non-orthogonal multiple access
(NOMA) systems IEEE access 4 6325-6343
[2] ARAFA A SHIN W VAEZI M amp POOR H V
2019a Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
15 210-222
[3] ARAFA A SHIN W VAEZI M amp POOR H V
2019b Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
[4] CAO K WANG B DING H LI T amp GONG F
2019 Optimal Relay Selection for Secure NOMA
Systems under Untrusted Users IEEE Transactions
on Vehicular Technology
[5] DANG S CHEN G amp COON J P 2018
Multicarrier relay selection for full-duplex relay-
assisted OFDM D2D systems IEEE Transactions on
Vehicular Technology 67 7204-7218
[6] DANG S COON J P amp CHEN G 2017 Outage
performance of two-hop OFDM systems with
spatially random decode-and-forward relays IEEE
Access 5 27514-27524
[7] FIANU S amp DAVIS L B 2018 A Markov decision
process model for equitable distribution of supplies
under uncertainty European Journal of Operational
Research 264 1101-1115
[8] FURQAN H M HAMAMREH J amp ARSLAN H
2019 Physical Layer Security for NOMA
Requirements Merits Challenges and
Recommendations arXiv preprint arXiv190505064
[9] HOU L ZHENG K CHATZIMISIOS P amp FENG Y
2018 A Continuous-Time Markov decision process-
based resource allocation scheme in vehicular cloud
for mobile video services Computer
Communications 118 140-147
[10] KOKSHOORN M CHEN H WANG P LI Y amp
VUCETIC B 2016 Millimeter wave MIMO channel
estimation using overlapped beam patterns and rate
adaptation IEEE Transactions on Signal Processing
65 601-616
[11] LIU Y ELKASHLAN M DING Z amp
KARAGIANNIDIS G K 2016 Fairness of user
clustering in MIMO non-orthogonal multiple access
systems IEEE Communications Letters 20 1465-
1468
[12] LV L CHEN J NI Q amp DING Z 2017 Design of
cooperative non-orthogonal multicast cognitive
multiple access for 5G systems User scheduling and
performance analysis IEEE Transactions on
Communications 65 2641-2656
[13] SUN Y NG D W K ZHU J amp SCHOBER R
2018 Robust and secure resource allocation for full-
duplex MISO multicarrier NOMA systems IEEE
Transactions on Communications 66 4119-4137
[14] ZHANG H YANG N LONG K PAN M
KARAGIANNIDIS G K amp LEUNG V C 2018
Secure communications in NOMA system
Subcarrier assignment and power allocation IEEE
Journal on Selected Areas in Communications 36
1441-1452
[15] ZHAO T LI G ZHANG G amp ZHANG C-X
Security-Enhanced User Pairing for MISO-NOMA
Downlink Transmission 2018 IEEE Global
Communications Conference (GLOBECOM) 2018
IEEE 1-6
DECLARATION
I declare that the thesis entitled lsquoHeterogeneous Wireless Network using Non-
Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo submitted
by me for the degree of Doctor of Philosophy is the record of research work carried out
by me during the period from January 2014 to November 2021 under the supervision
of Dr Chetan B Bhatt and this has not formed the basis for the award of any degree
diploma associateship fellowship titles in this or any other University or other
institution of higher learning
I further declare that the material obtained from other sources has been duly
acknowledged in the thesis I shall be solely responsible for any plagiarism or other
irregularities if noticed in the thesis
Signature of the Research Scholar Date 17092021
Name of Research Scholar Pankaj Manubhai Patel
Place Ahmedabad
CERTIFICATE
I certify that the work incorporated in the thesis lsquoHeterogeneous Wireless Network
using Non-Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo
was submitted by Shri Pankaj Manubhai Patel was carried out by the candidate under
my supervisionguidance To the best of my knowledge (i) the candidate has not
submitted the same research work to any other institution for any degreediploma
Associateship Fellowship or other similar titles (ii) the thesis submitted is a record of
original research work done by the Research Scholar during the period of study under
my supervision and (iii) the thesis represents independent research work on the part of
the Research Scholar
Signature of Supervisor Date 17092021
Name of Supervisor Dr Chetan B Bhatt
Place Ahmedabad
Coursework Completion Certificate
This is to certify that Mr Pankaj Manubhai Patel enrolment No 139997111012 is a
PhD scholar enrolled in the PhD program in the branch Electronics and
communication Engineering of Gujarat Technological University Ahmedabad
(Please tick the relevant option(s))
HeShe has been exempted from the coursework (successfully completed during
the MPhil Course)
HeShe has been exempted from Research Methodology Course only
(successfully completed during the MPhil Course)
HeShe has successfully completed the PhD coursework for the partial
requirement for the award of PhD Degree His Her performance in the
coursework is as follows
Grade Obtained in Research Methodology
(PH001)
Grade Obtained in Self Study Course
(Core Subject)
(PH002)
BC BB
Supervisorrsquos Sign
Name of supervisor Dr Chetan B Bhat
Originality Report Certificate
It is certified that PhD Thesis titled lsquoHeterogeneous Wireless Network using Non-
Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo by Shri
Pankaj Manubhai Patel has been examined by us We undertake the following
a The thesis has significant new workknowledge as compared to already
published or is under consideration to be published elsewhere No sentence
equation diagram table paragraph or section has been copied verbatim from
previous work unless it is placed under quotation marks and duly referenced
b The work presented is original and the own work of the author (ie There is no
plagiarism) No ideas processes results or words of others have been presented
as the Authors own work
c There is no fabrication of data or results which have been compiledanalyzed
d There is no falsification by manipulating research materials equipment or
processes or changing or omitting data or results such that the research is not
accurately represented in the research record
e The thesis has been checked using (copy of originality report attached) and found
within the limits as per GTU Plagiarism Policy and instructions issued from time
to time (ie Permitted similarity index lt=25)
Signature of the Research Scholar Date 17092021
Name of Research Scholar Pankaj Manubhai Patel
Place Ahmedabad
Signature of Supervisor Date 17092021
Name of Supervisor Dr Chetan B Bhatt
Place Ahmedabad
132
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Submitted 2021-09-22 091500
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Submitted by ap_rgandhigtueduin
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URL httpsarxivorgpdf190208992
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1
SODH PAPER FOR PLAGRIASMdocxDocument SODH PAPER FOR PLAGRIASMdocx (D47816804)
1
PhD THESIS Non-Exclusive License to
GUJARAT TECHNOLOGICAL UNIVERSITY
In consideration of being a PhD Research Scholar at GTU and in the interests of the
facilitation of research at GTU and elsewhere I Pankaj Manubhai Patel has Enrollment
No139997111012 hereby grants a non-exclusive royalty-free and perpetual license to
GTU on the following terms
a) GTU is permitted to archive reproduce and distribute my thesis in whole or in part
andor my abstract in whole or in part (referred to collectively as the ldquoWorkrdquo) anywhere
in the world for non-commercial purposes in all forms of media
b) GTU is permitted to authorize sub-lease sub-contract or procure any of the acts
mentioned in paragraph (a)
c) GTU is authorized to submit the Work at any National International Library under
the authority of their ldquoThesis Non-Exclusive Licenserdquo
d) The Universal Copyright Notice (copy) shall appear on all copies made under the authority
of this license e) I undertake to submit my thesis through my University to any Library
and Archives Any abstract submitted with the thesis will be considered to form part of
the thesis
f) I represent that my thesis is my original work does not infringe any rights of others
including privacy rights and that I have the right to make the grant conferred by this
nonexclusive license
g) If third party copyrighted material was included in my thesis for which under the terms
of the Copyright Act written permission from the copyright owners is required I have
obtained such permission from the copyright owners to do the acts mentioned in paragraph
(a) above for the full term of copyright protection
h) I retain copyright ownership and moral rights in my thesis and may deal with the
copyright in my thesis in any way consistent with the rights granted by me to my
university in this non-exclusive license
i) I further promise to inform any person to whom I may hereafter assign or license my
copyright in my thesis of the rights granted by me to my university in this non-exclusive
license
j) I am aware of and agree to accept the conditions and regulations of a PhD including
all policy matters related to authorship and plagiarism
Signature of the Research Scholar
Name of Research Scholar Pankaj Manubhai Patel Date 17092021
Place Ahmedabad
Signature of Supervisor
Name of Supervisor Dr Chetan B Bhatt Date 17092021
Place Ahmedabad
Seal
i
ABSTRACT
The landscape of future fifth-generation (5G) radio access networks is
expected to seamlessly and ubiquitously connect everything and
support higher traffic volumes densely connected wireless devices and
diversified requirements on reliability latency battery lifetime etc as
opposed to the current fourth-generation (4G) cellular networks
Moreover in unexpected or emergencies (such as disaster relief and
service recovery) the deployment of terrestrial infrastructures is
economically infeasible and challenging due to high operational
expenditure as well as sophisticated and volatile environments To
address such novel issues intelligent heterogeneous architecture by
leveraging unmanned aerial vehicles (UAVs) (or commonly known as
drones) has been considered to be a promising new paradigm To
improve the system performance of UAV communication in 5G
networks physical layer techniques are of much concern as they affect
the applications of UAVs significantly In this research work security
aspects of NOMA-based UAV communication network have been
considered for optimization as physical layer security in a wireless
communication network is not as robust as wired communication due to
fading and varying SNR scenarios Here primarily two usersrsquo models
as the trusted and untrusted user communicating with BS have been
optimized for outage-optimal performance considering pair Outage
probability and Secrecy outage probability as performance metrics The
achieved results are extended to multi-user scenarios also and for the
optimal policymaking dynamic programming and Partially Observable
Markov Decision Process (POMDP) optimization approaches have
ii
been simulated and verified The simulated results have shown that
POMDP has potential consideration as a resource scheduling
optimization technique in the NOMA-UAV communication network for
providing secure and more robust performance
iii
Acknowledgment
Completing a PhD is a tough task that requires hard work and a lot of effort This is
often an overwhelming but also great experience that I would not have been able to
complete without the assistance and support of so many people Thus it is my great
pleasure to thank all those people First of all I would like to thank almighty for giving
me the strength to carry out this task I would like to deeply thank Dr Chetan B Bhatt
my supervisor for his guidance encouragement and support over these years This
research work would not have been possible without his constructive pieces of advice his
systematic guidance and his patient support thought out the duration of my research work
I would like to express my sincere gratitude to Dr Harshal A ALOORKAR and Dr
KIRAN R TRIVEDI Dr Mehul Raval my doctoral progress committee members Their
rigorous style of reviewing and constructive feedback with valuable suggestions of Dr
Prakash Gajjar Mr Hitesh Panchal and Mrs Monali Mandli who spent their valuable
time whenever required for discussing aspects of this work and provided relevant material
as well Mr Parth Modi and Mr Jagadish Patankar to initiate and inspired me a lot to
continue my work Mr Mukesh Sharma who help in maintain documents I am also
thankful to my parents and family members who always stood with me in each critical
situation and supported me endlessly I am thankful to all EC departments of various
polytechnic and degree engineer colleges for their cooperation in every possible means
Lastly I would thank all the people who directly or indirectly helped me during this very
important phase of my life
Pankaj Manubhai Patel
vi
List of Abbreviation
3GPP 3rd Generation Partnership Project
5G Fifth Generation
A2G Air to Ground
AWGN Additive White Gaussian Noise
BDM Bit Division Multiplexing
BS Base Station
BPCU Bits Per Channel Use
CDMA Code Division Multiple Access
CR Cognitive Radio
CSI Channel State Information
CNPC Control and Non-Payload Communications
CRN Cognitive Radio Networks
D2D Device-to-Device
DCP Difference of Concave Programing
DOMP Dynamic Optimization Method of Programming
FR Floating Relay
GSM Global System for Mobile Communications
HLPSL High-Level Protocol Specification Language
ICT Information and Communication Technology
IoT Internet of Things
IRS Intelligent Reflecting Surface
IMT Information Management Technology
vi
LDS Low-Density Spreading
LTE Long Term Evolution
LTE-A Long Term Evolution Advance
MCR Multicast Cognitive Radio
MI Mobile Internet
MIMO Massive Multiple-Input Multiple-Output
mm-Wave millimeter Wave
MTC Machine-Type Communication
MUSA Multi-User Mutual Access
NOMA Non-Orthogonal Multiple Access
OFDMA Orthogonal Frequency Division Multiple Access
OMA Orthogonal Multiple Access
OP Outage Probability
POMDP Partially Observable Markov Decision Process
PLS Physical Layer Security
PDMA Pattern Division Multiplexing Control
PUN Primary User Networks
QoS Quality of Service
RIS Reconfigurable Intelligent Surface
RNRF Random Near-Random Far
Rs Target Secrecy Rate
SAGIN Space-Air-Ground Integrated Networks
SIC Successive Interference Cancellation
STBC Space-Time Block Coding
vi
SBF Secrecy Beam Forming
SCMA Sparse Code Multiple Access
SOP Secrecy Outage Probability
TAS Transmit Antenna Selection
TDMA Time Division Multiple Access
UAVC Unmanned Aerial Vehicle Communication
UMTS Universal Mobile Telecommunication Systems
URLLC Ultra-Reliable Low Latency Communication
vii
List of Figures
Figure Title Page
No
11 Usage of wireless sensor network and UAV in the
hazardous disaster control
6
12 UAV network applications types with security services
architecture
8
13 UAV-assisted heterogeneous network architecture 12
14 Security problems in the UAV 15
15 Comparative analysis of NOMA vrsquos OMA 18
21 Vehicular communication NOMA system 28
22 RS-NOMA against an external eavesdropper 31
31 Downlink NOMA network 44
32 Uplink NOMA network 46
33 Multi-two user architecture of NOMA system 49
34 Flow Diagram of the proposed system 50
35 Near and Far User 51
41 Impact on Sop with increase distance between BS and user U2 60
42 Impact on Sop with increase distance between BS and user U2 61
43 Feasible pairing t Vs pair OP 61
44 Infeasible pairing t Vs pair OP 62
45 Secrecy outage probability 63
46 Pair outage probability 63
47 SNR versus Strictly positive secrecy rate 64
48 Power radiated by per MMBs antenna 64
viii
List of Tables
Table Title Page
No
11 Physical layer hazards and measures in UAV wireless
communication network
13
21 Comparative analysis 33
31 List of parameters59 54
41 Simulation parameters 59
ix
Table of Content
Sr
No
Title Page
No
I Abstract I
II Acknowledgment II
III List of Abbreviation III
IV List of Figures Iv
V List of tables V
1 Introduction 1
11 Modern technology and its needs 1
111 Long term evolution of 4G network 2
112 Migration from 4G LTE to 5G for UAV communication 3
12 UAV assisted communication in heterogenous sensor network 5
121 Introduction to UAV Communication network 7
122 Tyews of UAVs 8
1221 UAVs as flying BSs 8
1222 UAVs as aerial UBs 10
13 Unmanned aerial vehicle for 5G network 11
14 Physical layer insecurity in UAV communication network 12
141 Principles of security 13
15 Non-Orthogonal Multiple Access (NOMA) system secured
communication
16
151 Comparison of NOMA Vs OMA 16
1511 Spectral throughput and efficiency 17
1512 User fairness and higher lately 17
1513 Compatibility 17
16 Problem identification 18
17 Motivation 19
18 Aim and objective of the research 20
19 Thesis organization 21
2 Literature review 23
x
21 Integration of UAV Networks for 5G and B5G communication 23
22 UAV-NOMA in physical layer security enhancement 26
23 Research methodology 38
24 Summary 39
3 System model for NOMA-UAV communication 41
31 NOMA -UAV system secured communication for 5G 41
311 The basic scheme of NOMA 41
312 Downlink of NOMA 44
313 Uplink of NOMA 46
314 Comparison of NOMA and OMA 47
32 PLS performance metrics in NOMA -UAV communication 47
321 SOP and OP - two user and multi-user NOMA system 48
322 System Model 48
323 Partially Observable Markov Decision Process-POMDP 50
324 Problem formulation 52
33 Performance Analysis Improving PLS Insecurity of NOMA
System
53
331 The pair OP calculation 53
332 Pseudo-code for the proposed algorithm 55
34 Summary 57
4 Result and discussion 58
41 Performance measure of secured NOMA-UAV communication
model
58
42 Numerical result and discussion 59
421 Feasible amp Infeasible pairing of trusted amp untrusted
users
60
422 The secrecy outage probability and pair outage
probability
62
423 SNR versus strictly positive secrecy rate 63
424 Power radiated by per MMBs antenna
64
43 Conclusion and scope of future work 65
431 Conclusion 65
432 Future scope 66
xi
5 References 67
8
Publications 78
1
CHAPTER -1
INTRODUCTION
11 Modern technology and its needs
Mobile technology has undergone various generational shifts transforming the
cellular framework into a worldwide set of interconnected networks In recent days
the fifth generation (5G) has delivered voice as well as video streaming It has a
very complex range of networking services for more than nine billion users and also
billions of devices that will be connected (Hu 2016) However 5G offers a new
outlet for reflection It involves a radial network architecture for the installation of
communication-type machines 5G network can also include powerful support
applications with widely varying operating parameters 5G is a blend of network
technologies that have been developed The new 5G technology will be able to
exchange information anywhere every time for the benefit of people enterprise
and society and technical environments using a restricted access bandwidth to
carry data Now it is more than a modern series of technologies and as opposed to
previous generations would entail tremendous infrastructure or machinery
upgrades This technology aims to expand on the advances that telecommunications
systems have already achieved The projected standards of efficiency that
technologies would need to resolve are
bull Five times reduce end-end latency
bull Ten to a hundred times the higher complex rate of user data
bull Battery life is ten times longer
bull 10 to 100 times higher number of connected devices
In this research work the UAV-assisted communication over the 5G network has
been proposed with enhanced physical layer security aspects NOMA has been
proposed as the reference framework architecture for UAV communication as one
of the recent popular 5G techniques Along with the advantage of suitability in UAV
communication network NOMA has the disadvantage of insecurity in the physical
layer Here the migration of Long Term Evolution (LTE) to advanced physical layer
2
security for Unmanned Aerial Vehicle communication (UAV) over 5G network has
been proposed and also improve the insecurity of Non-Orthogonal Multiple Access
(NOMA) System We will discuss in the further chapter the proposed work This
chapter describes the introduction and basic concepts of the 5G networks with
methodology techniques and types It states the problem identification motivation
and further aim and objective of this work
111 Long Term Evolution of 4G Network
LTE is customary for 4G wireless broadband trends that provide improved network
capability and gives mobile device users speed It offers high peak data transform
rates in the range of 100 Mbps and 30 Mbps downstream and upstream
respectively It provides a capacity of scalable bandwidth mitigated latency and
backward compatibility with the previous Global System for Mobile
Communications (GSM) and Universal Mobile Telecommunication Systems
(UMTS) technology
The fourth development of cellular networks (4G) has already been developed to
meet the standards of the 3G and 2G families Every 10th year a new mobile
generation claimed to be familiarized with the first 1G system in 1981 tracked by
the 2G system that went on to roll out in 1992 and 3G launched in 2001 growth in
the year 2002 of 4G networks The actual new revolution began in December 1998
with the 3rd Generation Partnership Project (3GPP) With high-quality video and
images 3G networks are designed for multimedia networking with them Peoples
communication can also be enhanced and connectivity to public and private
network information and resources has improved with higher frequencies and new
flexible communication features third-party device applications
With the start of LTE-Advanced several vital demands and improvements are
beginning to emerge Various importance purposed for LTE-Advanced can be
exemplified as follows (Abed)
bull Provides spectrum output with LTE delivered more than three times
bull Spectrum can help scalable bandwidth and convergence of the spectrum
where it is necessary to use a non-contiguous range
3
bull Provides uplink and downlink spectrum output that varies between
15bpsHz and 30bpsHz
bull The edge throughput must be twice that of the user cell in LTE
bull From idle status to connected status the communication latency scenario is
smaller than 50msec and less than 5msec for direct packet transfer
bull Any users total throughput must be three times that of LTE
bull LTE advancement will provide 3GPP as well as LTE compatibility via inter
networking
bull The mobility conditions that are used in LTE are identical
The latest LTE advanced requirements are not yet included in device
specifications there are high-level purposes Before it is fixed in the specifications
and needs to be tested much effort remains to be approved
112 Migration from 4G LTE to 5G for UAV communication
The productive implementation of a UAV communication network in 4G and the
upcoming wireless network is included in identifying combined solutions to test
the correlation with both multitudes and also energy-efficient transmission Then
the process of the UAV-BS to optimize coverage and power It is stated that the
energy efficiency of the UAV-aided communication system is needed Efficient
energy utilization contributes to increased air time in the contact system and
increased joulesbits at a provided energy level Also aerial cell coverage and
ability may be because of various parameters such as antenna gains transmission
strength radio access technology UAV altitude and deployment environment
4G is the fourth generation of network infrastructure technologies to replace 3G and
in addition to the popular 3G4G methods Code Division Multiple Access
(CDMA) Time Division Multiple Access (TDMA) and Orthogonal Frequency
Division Multiple Access (OFDMA) Researchers are designing the latest Non-
Orthogonal Multiple Access (NOMA) technologies to be used because of their
capability to improve the performance of communication networks Non-
4
orthogonality-based device designs have recently been developed for use in
communication networks and drawn considerable interest from researchers
Henceforth Multiple Access (MA) methods can be sub-divided as OMA and
NOMA Each user may utilize orthogonal communication resources to determine
multiple access interference inside a frequency band code and time slot in OMA
Its methods such as First generation (1G)- FDMA 2G -TDMA 3G -CDMA and
4G - OFDMA have been used in previous network generations In NOMA by
producing a higher spectral efficiency however enabling some amount of multiple
entree intrusion in receivers and multiple users may use non-orthogonal resources
simultaneously Recently the credibility of NOMA as a solution to the problems of
the next generation of wireless networks has been increased Compared with OMA
technologies NOMA has been described to improve spectral quality be well-
adjusted with air connectivity and can provide accommodations for multiple
strategies at the same time of frequency Therefore enabling excellent progress to
massively correlated devices
In particular NOMA also affects mitigating interference by using OFDMA as an
orthogonal method or through offering a standard intra-cluster access beam across
multiple users and inter-cluster access in NOMA Recent studies have concentrated
primarily on the provision of Air to Ground (A2G) connectivity services through
optimization of a different point of view
The output of the UAV-based communication network was discussed in the Device
to Device (D2D) implementation setup The proposed system hypothesized
interference caused through D2D network nodes deprived of acknowledging the
occurrence of global BS Also several studies addressed the efficiency of NOMA
It permitted the deployment of fixed-wing to assist coverage in-ground user located
outer location of offloaded BS
NOMA systems are divided into two categories namely code domain and power
domain multiplexing In the power domain user accounts are allocated to different
power coefficients as per their channel complaint to reach optimal device
efficiency Multiple user signals are applied to the side of the sender Then on the
received signal Successive Interference Cancellation (SIC) is implemented to
decipher signals in sequential order until the predicted signal is achieved offering
5
a good trade-off between efficiency of the system and user fairness Different code
domain multiplexing is Sparse Code Multiple Access (SCMA) Low-Density
Spreading (LDS) and Multi-User Mutual Access (MUSA) Compared to power and
code domain multiplexing there are alternate NOMA techniques such as Bit
Division Multiplexing (BDM) and Pattern Division Multiplexing Control (PDMA)
However this multiplexing is capable of improving the efficacy of spectral It
requires a large transfer of bandwidth which is not appropriate for new methods
But on the other side the power domain has direct execution since there is no need
for significant improvements to the current networks It also does not necessitate
bandwidth to increase spectral efficiency In this chapter the main emphasis
depends on the power domain NOMA While OMA strategies can produce the best
results also with necessary receivers due to no mutual intervention among users in
an optimal situation they cannot even resolve increasing problems due to growing
demands on connectivity growth and even beyond
12 UAV assisted communication in heterogeneous sensor network
Wireless communications had created a golden chance for urban and rural
territories The LTE (Long term evolution) and LTE-A (Long term evolution
Advance) had offered the service (with QoS) for all customers through wireless
The traffic properties in the machine type communications (MTC) and the
accumulation of the MI (Mobile Internet) had made the difficulty of implementing
the cellular communication networks Installing base stations was impractical in the
urban areas due to its cost To overcome this issue the UAV suggested that it
contains the merits of compatibility and high battery life and is affordable Most of
the devices like the sensor nodes and professional cameras had been used in UAV-
assisted networks Here the UAV-assisted floating relay (FR) was launched in the
cellular communication networks UAVs were implemented more with WSN
(wireless sensor networks) The base stations were adopted with the UAV So the
MI and MTC traffic challenges were controlled (Yue Li amp Cai 2017)
UAV-assisted Heterogeneous networks had implemented in vast practical
applications UAV helped heterogeneous networks were applied in the military
department In the military the UAV had examined and surveyed the opposing
6
countryrsquos activities for security The UAV-based heterogeneous networks were
used in the military sectors where a novel authentication scheme was introduced
As The one-to-one communication via WSN was considered as secured
communication WSN had the disadvantage of consuming power The
authentication was implemented in the tool of Automated Validation
of Internet Security Protocols and Applications (AVISPA) in which the expression
had been written in the High-Level Protocol Specification Language (HLPSL)
programming language The authentication had evaluated between the user and the
base station Similarly the authentication between the user and the UAV was
calibrated The citizen and economic safety are predicted and conserved through
reliable communication in the military by obtaining foes exploration information
The faithful secured communication was confirmed using AVISPA (Rashid et al
2019)
Figure 11 Usage of wireless sensor network and UAV in the hazardous
disaster control
The integration of the wireless sensor networks and the unmanned aerial vehicle
UAV was analyzed and applied to manage the natural disaster illustrated in Figure
11 The aircraft can prevent the fire spreading drop sensors the temperature map
and biodiversity map by sensors the wildfire can easily route The wild animals can
7
be tracked and the dynamic data of moving animals can be gathered by WSNs The
biologists can fix the sensor in the animals collar the radiation that positively
affects humans can be observed in affected areas The WSNs help to prevent heart
attack of a person by monitoring heart rate The state of health can be known
through a message alarm using a GPRS system
The cooperative networks of WSN and UAV were implemented in the military
sector for the advantageous feature The UAV was providing good connections
overlapping and overall data rate The conventional UAV method aided sensor
networks concentrated only on the single tasks of monitoring accumulating
information and localization The multi-UAV had not been implemented in the
sensor networks The animal colony perception technique was utilized for
scheduling the resourced and the target assignment Functions of multi-data were
used for localization by the target recognition method (Gu Su et al 2018)
The Physical Layer Security (PLS) was achieved through 5G technologies delicate
coding for the PLS dense MIMO multi-input multi-output mm-Wave frequency
band using heterogeneous sensor networks NOMA and full-duplex mode of
communication IoT and Machine-type communications (MTC) emerged in the 5G
systems (Wu et al 2018)
121 Introduction to UAV communication network
The usage of the UAV will develop more in the next era These pre-programmed
aircraft are intended for applications in several civil settings as well as industrial
visualization agriculture rescue and search and then receiving of scientific data
These devices are called the unsuccessful inaccuracy of drones which must be
incorporated into the system of national airspace as well as worldwide The usage
of UAVs in the neutral form is always secure It has a direct inference for the control
and a payload communication system that is utilized to function effectively
Similarly surveillance and navigation operations must be made more accurate and
consistent Due to these critical factors many kinds of research in a UAV testing
development and standardization difficulties are undergone through industries
education and governments
8
Even though civil aircraft had been operating for many years yet UAV offers new
consequences in terms of various flight profiles For example high dynamic
maneuvers and low elevation flights need bandwidth video and different ground
site characteristics namely clutter locations and elevation antennas which are low
This chapter explains the core topic of the proposed work The migration of LTE
4G towards the advanced one of the physical layers for UAV communication It has
higher mobility and lower expense identified in a broad range of applications
122 Types of UAVs
The UAVs have a two-network application with security services such as UAVs as
Flying Base Stations (BSs) and UAVs as Aerial BSs in the presence of
eavesdroppers
(a) UAVs as Flying BSs (b) UAVs as Aerial mobile UEs
Figure 12 UAV network applications types with security services
architecture
1221 UAVs as flying BSs
The required infrastructure can be destroyed in natural disasters particularly
tsunamis earthquakes and snowstorms and the requisite emergency data traffic
cause both overloading and congestion of neighboring mm-Wave (Zeng et al
2016) A capable explanation is to rapidly introduce low-altitude UAVs as flying
9
BSs in such a network breakdown to improve the communication infrastructure to
mitigate cell congestion or site failure thus creating a small aerial cell
In this situation wireless communications can occur in an ad-hoc manner with
UAVs to UEs UAVs to UAVs As highlighted in Figure-12 (a) and control
stations of UAVs to ground It will increase capability dramatically and enlarge the
target of wireless networks in provisional measures as it is possible to create LoS
communication links among UAVs and UEs supported on the ground Yet form an
operating aerial cell system to monitor ground segments of UEs mobility which is
more stable to minimize sporadic connectivity on the other side
Also this can be expanded to allow several UAVs-BSs to be deployed to increase
the exposure area for supporting a wide range of UEs A network period various
UAVs-BSs is entirely independent A new paradigm was introduced through
collaboration between UAVs-BSs to extend the feasibility for a single UAV from
either a stand-alone active sensor to a wireless network over the next generation
There is a growing concern about the privacy problem in tandem with the brief
introduction of this network Wireless protection is the central issue of the
communication level wherever eavesdropping subsidizes for deliberately listening
to a source of secret information which harms the extensive placement of UAV-
BSs
A UAV-BSs is to mount several antennas in the UAV-BSs the benefits of multi-
antenna innovations geographical degree of freedom that offers an ability for UAV-
BSs to transmit eavesdropping airborne beams
Notice that in UAV systems multi-antenna technology can be technically applied
while directly modifying the separation of the antennas The existing system has
shown that transmitted beam forming models can significantly boost the
confidentiality efficiency of wiretap channels for multiple antenna transmitters
Noise may be inserted with the signal to substantially degrade the acknowledged
SINR at the eavesdroppers to prevent the information overflow
10
1222 UAVs as aerial UEs
This has already been demonstrated by reaping the benefits of Wi-Fi and LTE
technologies through field trials (Van der Bergh et al 2016) UAV-UEs typically
get their tasks for a variety of convincing IoT applications mainly in air freight
services like the google wing project Unlike conventional land base package
delivery but UAV delivery has distinctive merits such as
bull Acceleration of land transport as UAVs are not liable to road jams
bull Connection to areas that are difficult to reach
bull Decreasing the use of capital about workforce and electricity
UAV distribution is significantly dependent on having reliable and secure wireless
communication among UAVs and ground BSs especially if the UAV needs control
outside LoS the UAV-UEs are used which can develop LoS connectivity to cellular
BSs The UAV-UEs on the one hand provides high-speed access to data as it can
fly continuously in either direction On the other hand the installation of UAV-UEs
can lead to significant interference with the ground BSs in the execution of their
missions
A wide-scale installation of UAV-UEs is only feasible for this reason if the issues
of interference management are tackled It is widely known that interference
negatively affects wireless networks As highlighted in Figure-12 (b) indeed aerial
and ground UEs are served through a cellular network with a possible eavesdropper
that tries to intercept the message intended for permissible basic UEs
A cost-effective approach is to be used for coordination among ground BS and
UAVs to enhance secure transmission which is part of the UAVs acting as friendly
transmitters to degrade the wiretapping channels efficiency and thus enhance
secrecy efficiency A UAV acting as a mobile jammer can dramatically and
dynamically change its position as near as possible to the earth eavesdropper and
distribute them by sending the radio signals whereas strong LOS connection
characteristics are a beneficial feature with less earthly fading and shadowing
impairment
11
13 Unmanned Aerial Vehicle for 5G Networks
UAVs have technologically advanced as a revolutionary movement in delivering
pervasive connectivity from either the platforms of the sky as aerial
communication particularly for temporary User Equipment (UEs) (B Li et al
2019) Due to fully controllable UAV flexibility through miniaturization as well as
continuous cost reduction low-altitude UAVs are rapid and flexible designed for
operation and reconfiguration They are probable to have higher Line-of-Sight
(LoS) ties to ground UEs
A broad range of applications like inspection of infrastructure precision farming
and disaster area monitoring is becoming accessible in this aspect Moreover
further projects have also been set up to employ aerial platforms for broadband
access to distant elements such as the Google Loon and the Facebook Drone Project
to mention Highly populated UEs are desperate for broadband wireless
communications with the coming 5G period and network providers are supposed
to maintain numerous networks with high demands for wireless data like
multimedia streaming and also video downloads The relentless growth in the
amount of traffic of mobile networks puts a burden on operators in the form of
higher capital and operational expenditure Deploying small cell networks is an
intuitive alternative to outsource cellular traffic
Although in unforeseen or temporary events as mobile environments are
complicated volatile and heterogeneous the implementation of terrestrial
infrastructures is difficult The accessibility of aerial access points to enable
extensive complex connections is one possible solution However in unforeseen or
temporary events as mobile environments are complicated volatile and
heterogeneous the implementation of terrestrial infrastructures is difficult The
accessibility of aerial access points to enable extensive complex connections is one
possible solution UAV communication performance benefits from the simplicity
of the compact transceiver and progressive control methods that obtain broad
exposure and set up internet networks
12
Figure 13 UAV-assisted heterogeneous network architecture
The above Figure 13 is depicted to build flexibility of the network with enhanced
ability and elasticity It is a good network that offers security endowment This is
due to the transmitting information to UAV communication which is tapped
through ground unauthorized user and is known as an eavesdropper
Here through eavesdropper based on the upper layer cryptographic techniques
wireless communication in contradiction of unauthorized access has been protected
However it is very tough to achieve because of key management as well as more
computational difficulties in developing network architecture PLS affects the
characteristics of intrinsic wireless networks as a fascinating preparation such as
interference noise fading loss collecting signal characteristics in malicious
eavesdroppers and techniques of signal processing
14 Physical Layer Insecurity in UAV communication network
Jamming is either a well-defined WSN attack on a physical layer It disrupts the
radio waves being used by nodes of the network The attacker successively
expresses the denial of the simple MAC protocol over the wireless network The
impressive network can be disrupted at which a single frequency is being used
13
throughout a network (Modares et al 2011) In addition jamming can increase
energy consumption in the node by inserting impudent packets The receiver nodes
will also generate resources when receiving the packets In (Jeon 2006) four
different terms of jamming attacks that an intruder could use to interrupt the
wireless network activity Tampering is yet another physical layer assault
Table 11 Physical layer hazards and measures in UAV wireless
communication network
(Kumar et al 2014)
Hazard Security measures
Jamming Channel blacklisting and hopping
Interference Channel hopping and blacklisting
Tampering Security and key modification
Sybil Physical security of the system
Table 11 describes physical layer hazards and their security measures in WSN
which tampering and jamming are considered as the main attack in the physical
layer in WSN
141 Principles of security
The security requirement of UAV communication network is as follows (Kumar et
al 2014)
Confidentiality Ensure that only the approved sensor nodes could get the contents
of the texts
bull Authentication Ensure that the data is introduced from the sound source
bull Integrity Ensure that every received text has not been modified to be sent
by unauthorized users
14
bull Freshness Make confirm that no old information has been reiterated
bull Availability services are feasible at any time through WSN or by a single
node
The standard attacks of the physical layer are as follows (Sastry et al
2013)
bull Jamming The transmission of the radio signal can interfere only with radio
frequencies used through WSN which is known as jamming As the
capacity grows it may influence more significant portions of the network
by transmitting other radio signals The opponent will use a few nodes to
occupy the entire channel This state is called physical layer jamming which
results in a denial of service In this scenario the opponent will not be
permitted to have any knowledge but will be capable of preventing
communication to any nodes
bull Tampering Often the nodes tampered through an opponent This mode is
called tempering Here the attackers can destroy exchange and
electronically confront nodes to obtain information from counter measures
towards jamming that have been planned as spread as well as frequency
hopping
bull A security mechanism is used in WSN to track avoid and recover from
security attacks A wide range of security schemes can be devised to counter
malicious threats which can be classified as high and low levels
bull Secrecy and Authentication Most network sensor applications need
protection from eavesdropping packet alteration and injection Early
networks are used for connection layer cryptography as this approach offers
the easiest deployment of network cryptographic solutions
bull Privacy Like all other conventional networks the radio networks have also
brought secret issues to allow Initially sensor networks are implemented
for legitimate purposes and can eventually be used unexpectedly
Knowledge of active sensor nodes as well as the acquisition of data is
exceptionally crucial
15
bull Critical launch and trust setup The primary prerequisite for setting up a
network is the development of keys (cryptography) Sensor devices
typically have minimal computing capacity and public cryptographic
primitives are too difficult to adopt Critical establishment and strategies
need to be scaled to network with thousands of nodes
bull Secure routing Routing as well as data forwarding is a problem that
confronts to facilitate communication in networks Regrettably the latest
protocols encounter a variety of security flaws
bull Robustness of communication Does An opponent challenges to interrupt
the operation of the network
Figure 14 Security problems in the UAV
Figure 14 illustrated the security difficulties in a UAV The physical layer security
in the UAV wireless networks was examined The UAV had affected by both active
eavesdropper and passive eavesdropper This paper proposed the trajectory design
and cooperative UAV for constraining the eavesdropper NOMA MIMO mm-
Wave frequency band in UAV would cause better spectral efficiency and security
(Xiaofang Sun et al 2019)
UAV implementation of the 5G communication was considered advantageous The
UAV was assumed as the novel wireless network technique for the territory users
and their base stations The UAV had resulted in high altitude So the UAV had
16
considered a superior line of sight At the same time the possibility of security
problems was raised in a UAV The secrecy in the existence of eavesdropper the
jammer in the ground was performed using the UAV UAV aided territory security
was proposed The UAV was involved in inspecting the eavesdropper and hazard
jammers on the base stations territory UAV had targeted the global position system
spoofing for assisting the authentic users and performed the role of an artificial
eavesdropper for excluding the eavesdropper and jammers in the ground (H-M
Wang et al 2019)
15 Non-Orthogonal Multiple Access (NOMA) System Secured
Communication
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
151 Comparison of NOMA Vs OMA
Comparison of the NOMA and OMA can be discussed as follows
17
1511 Spectral throughput and efficiency
In OMA a resource is allotted to the distinct user whether it is good or bad in a
channel scenario like OFDMA Thus the whole process moves from less
throughput and performance
While the same frequency is allotted to the multiple-use at the same time with good
or bad channel operation in NOMA here the weak user gets the allocated for the
resources which the strong user can also use it And the interference can be reduced
by the SIC process on the receptor side of the user Consequently the probability
with the increased spectral efficiency as well the high throughput will be
maximized
1512 User fairness and higher lately
A user of fair channel complaints has higher precedence to be served in OMA In
contrast a user with a poor channel complaint is to remain activity which causes
the issue of user fairness and higher latency Yet OMA cannot assist colossal
connectivity Whereas NOMA helps multiple users with various channel
procedures and offers increased fairness massive connectivity and lower latency
1513 Compatibility
NOMA has compatibility with the current and upcoming scenario meanwhile no
need for necessary changes to the previous methods As an instance NOMA has
been bought up in the 3G Partnership Project LTE Advanced (3GPP LTE) Though
NOMA contains many characteristics that can assist the upcoming generations and
it has some restrictions that can be explored with its full benefits Those restrictions
are as follows
bull Each user has to decrypt the signals of other users until decrypted their
signal the complexity of the receiver would be strengthened in NOMA as
opposed to OMA which creates a long pause
bull Also data on channel quality for all users should be returned to the BS but
this results in substantial CSI input overhead Furthermore if any issues
arise to any consumer during the SIC process the likelihood of consecutive
decrypting errors will be improved
18
Figure 15 Comparative analysis of NOMA vrsquos OMA
As an outcome the number of users is reduced to ignore the spread of such
debugging Another aim of restricting the number of users is that there must be
substantial variations in channel revenues between users with different channel
grievances to provide network reliability
16 Problem Identification
The NOMA-based architectures main feature is to configure trusted and untrusted
users when more than one eavesdropper is present in the dense setting of todayrsquos
and future sophisticated wireless communication networks This research aims to
examine the security efficiency suggested for mission-critical applications in the
NOMA-based UAV communication network The proposed system underpins two
user NOMA frameworks The possibility of paring both users was explored with
PHY performance measures in mind Outage probability (OP) and Secrecy Outage
Probability (SOP) Dynamic Optimization Method Programming (DP) and Partially
Observable Markov Decision Process (POMDP) optimization have also been
analyzed to explore the feasibility of achieving an outage-optimal output for the
pair under the heavy users secrecy outage restriction The optimized theoretical
findings are applied to the multiuser scenario The identifications were tested
through a computer model in which POMDP has shown substantial progress over
the dynamic optimization method to program
19
17 Motivation
Unmanned aerial vehicle (UAV) wireless communications have experienced an
upsurge of interest in both military and civilian applications due to its high
mobility low cost on-demand deployment and inherent line-of-sight air-to-ground
channels However these benefits also make UAV wireless communication
systems vulnerable to malicious eavesdropping attacks
Despite the promising gains brought by UAVs the open nature of air-to-ground
wireless channels makes secure information transfer a challenging issue
specifically on the one hand information signals transmitted over wireless LoS
channels are likely to be intercepted by some undesired receivers which lead to a
risk of information leakage On the other hand wireless UAV transceivers are
vulnerable to malicious jamming attacks Hence security plays an extremely
important role in UAV wireless communications Unfortunately traditional
encryption techniques require high computational complexity leading to a large
amount of energy consumption which may not be suitable for UAV systems As an
alternative physical layer security is computationally efficient and effective in
safeguarding wireless communication networks via exploiting the inherent
randomness of wireless channels As a result various physical layer techniques
have been proposed in the literature for guaranteeing communication security
NOMA is viewed as a promising technique to provide superior spectral efficiency
by multiplexing information signals at different power levels [13] Hence it is
expected that NOMA can bring additional rate and robustness to enhance the
achievable rate in UAV physical layer security communications Consider a
scenario where a UAV acts as a relay to facilitate data delivery to two receivers
with different security clearance levels within a maximum cruising duration T The
receiver with a lower security clearance level and a higher potential with an
eavesdropper Since it has a strong motivation in intercepting signals intended for
a receiver with a higher security clearance Then when the eavesdropper suffers
from a bad channel condition NOMA is adopted to forward both confidential and
public information simultaneously Otherwise UAV only broadcasts the public
information for security issues The mode selection between NOMA and unicast is
20
chosen based on the results of the proposed resource allocation optimization In
particular for maximizing the spectral efficiency one needs to jointly optimize the
transmission scheme resource allocation and UAVrsquos trajectory However the
coupled optimization variables generally result in non-convex optimization
problems which are difficult to solve optimally As an alternative an iterative
suboptimal algorithm based on successive convex approximation can be employed
to facilitate a computationally efficient joint design We have discussed that the
NOMA scheme always outperforms OMA in all the considered scenarios which
demonstrates the spectral efficiency advantage brought by NOMA in striking a
balance between public data rate and confidential data rate
The main motive of this research is to enhance the inherently insecure PHY layer
of the NOMA-based UAV communication network NOMA-UAV communication
network requires feasible paring between trusted amp untrusted users (attacker) for
cooperative communication mainly in real-time field applications The power
allocation factor need to be optimized as per the trustworthiness of the associated
users (reliable user) and keeping the outage probability minimum for secured and
cooperative communications The pair Outage Probability and the SOP have been
optimized jointly for feasible pairing between BS amp the associated Users
18 Aim and Objective of the Research
The proposed works main objective is to examine the design of a NOMA-based
UAV communication network for enhanced Physical Layer security (PLS)
features Remarkably it is anticipated infrastructures and resources to connect
numerous devices and provide various services Researchers these days
concentrating on ways to design a heterogeneous framework like deployed small
cells air and ground-based deploy multifarious communication methods in 5G
such as millimeter-wave (mm-Wave) device-to-device (D2D) massive multiple-
input multiple-output (MIMO) Cognitive Radio (CR) and so on for improving
spectrum and energy efficiency
As a critical need especially for emergency applications the adoption of NOMA
transmission of UAV communication needs to be improved PLS A new optimal
resource allocation algorithm for some more robust and stable communication in
21
single and multiuser scenarios has been suggested here The PLS in dense
heterogeneous sensor networks has improved by the feasible pairing of trusted and
untrusted users (K Cao 2019 T Zhao 2018) In the instance of untrusted users
dynamic programming and POMDP are subjected to the channel conditions
details optimizing OP and SOP as a restricted parameter accompanied by resource
allocation (Davis 2018 L Hou 2018)
The main aim of the proposed research work areas
bull To analyze the underlying NOMA UAV communication framework with
enhanced Physical Layer security (PLS) implications for particular quest
applications
bull To examine the potential pairing of trusted and untrusted users in the
NOMA-based UAV contact network with two users and multiuser scenarios
for certain channel conditions called Channel State Information (CSI)
bull To maximize resource allocation among trusted and untrusted users by
pairing OP and Secret Outage Probability (SOP) as performance measures
with the POMDP optimization method
bull To evaluate POMDP and dynamic programming resource allocation with
two users and multiple users for both protected NOMA-based UAV
communication network scenarios
19 Thesis Organization
Chapter 1 Provides the introduction and basic concept of the proposed work with
the problem identification motivation and aim and objective of the proposed work
Here we described LTE 4G and its advanced techniques than about the NOMA and
its basic scheme UAV concepts represent their types and basic working strategy
Chapter 2 Provides a survey of the existing technologies which is related to the
proposed work The NOMA transmission schemes Merits and De-merits related
to security UAV assisted communication in heterogeneous sensor networks UAV
networks of 5G and beyond communications has been explained then about UAV-
NOMA PHY secured communication techniques as well
22
Chapter 3 Describes the proposed work of improvement of physical layer
insecurity of the NOMA The overflow and its performance measures with
simulated output have been defined in this chapter
Chapter 4 Describes Migrations proposed work from 4G LTE to advanced PHY
techniques for UAV communication The overflow and its performance measures
with simulated output have been explained in this chapter Concludes and explains
the proposed work with its outcome and the future scope of the proposed work
23
CHAPTER 2
LITERATURE REVIEW
21 Integration of UAV Networks for 5G and B5G communication
5G and B5G had been anticipated to give a unique connection among universal
users The UAV had been emerged for its advantage of wireless network and
relaying high data rate The UAV in the 5G and B5G was introduced and 5G and
B5G were updated with the new concept of Space-Air-Ground Integrated Networks
(SAGIN) Three layers were established named physical network communication
link and evaluation Besides the usage among the dense population IoT was
applied in satellite communication In which the IoT had provided the uninterrupted
service with high data rate communication The scope for flying UAVs had been
created for enhancing the number of mobile users with IoT (Ali et al 2018)
5G and B5G had projected the UAV as the vital constituent One to multiple point
transmission can be possibly advance in 5G and B5G The structural design of the
upcoming UAV (multi-tier drones) was driven by the routine of different structures
like the maximum functioning altitude communication overlap coverage and
determination The UAVs practicability (multi-tier drones) among conventional
UAVs (single-tier drones) is scrutinized in that perspective By ascertaining the
circumstances UAV (multi-tier drones) could supplement the older terrestrial
networks with RF Initially UAV (multi-tier drones) and drone-aided wireless
networks were related to finding the tasks The modified UAV (multi-tier drones)
and the drone-administered wireless networks were analyzed The enactments of
UAV (multi-tier drones) were scrutinized in the contest of spectral efficiency in the
downlink networks Their effect had exhibited the detailed network parameters The
UAV distribution (multi-tier drones) was considered advantageous for the spectral
efficiency from the downlink transmission over traditional terrestrial wireless
networks (Sekander et al 2018)
The growth of 5G and B5G wireless networks prominently hang on the
incorporation of the terrestrial and aerial systems in innovative heterogeneous
network architecture They had advanced a creative and tangible multiple UAV
24
made up of cluster UAV ndash base stations and Poisson point process with UAV and
mm-Wave frequency band Ground user equipment and UAV had exhibited as the
Poisson cluster process and then spread around the public cluster in the distinctive
cluster In particular the scrutiny was accompanied by the accumulation of extra
tiers Extra tiers were made up of multi-cluster UAV base stations and single ground
user base stations in the characteristic cluster Four-tier network systems were
designed correspondingly from the subdivision of the above-said base stations
Two-tier and four-tier association patterns were built for discovering the
involvement of the cluster networks The coverage probability for the downlink and
network throughput was derived (Ji et al 2020) The numerous subordinate title
role of the multifaceted communication systems was performed by the UAVs The
UAV was acted as the air relay in the maintenance of ground networks The UAVs
were used in the countryside hilly zones whereas the communication was
inadequate The author anticipated resolving the viable communication difficulty in
5G and B5G vehicular ad-hoc The associate communication pattern established on
the smart UAVs was planned given the crisis condition of the car ad-hoc The smart
UAVs were supporting the vehicular ad-hoc strong communication in real
situations Above and beyond its actual characteristics of the vehicular ad-hoc were
needed to be endangered to avoid the prohibited features from attaining and
exhausting for law-breaking practices Innovative UAV with a secret authentication
key arrangement was recommended in the 5G and B5G vehicular ad-hoc Because
of supporting efficiency the vehicle network which guaranteed communication
confidentiality was not negotiated The suggested pattern was confirmed to be
unaffected by numerous outbreaks by exploiting the broadly applied natural or
random ROR scheme
Furthermore the projected scheme had well calibrated the communication
overhead from the performance estimation (J Zhang et al 2020) The UANs had
obtained a phenomenal role in the research area the emergent sector of aerial
robotics The parcel transport organization monitoring occurrence shooting
surveillance and tracing were the metropolises general operations utilizing the
UAV Various domains would use 5G and B5G to improve UAV networks UAV
ecological unit was advantageous in present 5G and B5G mobile communications
For UAVs intrinsic features they were concerned for flexible movement of three-
25
dimensional space independent actions and smart locations These devices were
provided with extensive scope in cellular networks The author proposed an in-
depth assessment of implementing cooperation between UAV and 5G and B5G In
which UAV had been assimilated as a novel user equipment of aerial in present
mobile communications The UAV had implemented the duty of flying users within
the network coverage named the cellular-connected UAVs in this amalgamation
The author showed a broad examination of the incorporation tasks with 5G and
B5G novelties Continued efforts in the prototyping and validation of mobile
communication UAVs were conducted using the ground trial The paper had
focused on the current growth in 3GPP The social-economic had not been taken
into account which was considered disadvantageous (Mishra amp Natalizio 2020)
The UAV was anticipated as the significant constituent in the 5G and B5G wireless
networks 5G enables the UAV to be used in broadcasting and end-to-end
communications using the small UAV They needed a devoted and endangered
aerial spectrum in the aircraft cargo by letting small UAVs run in space in
supervisory authority The security information was obtained from the link Control
and Non-Payload Communications (CNPC) The security information contained
the regulation of UAV and the line of sight of terrestrial The CNPC application in
the 5G and satellite communication was scrutinized in this paper Payload
communication like mm-Wave networks and UAV were analyzed in this paper The
direction-finding and reconnaissance difficulties were examined UAV
communication systems were scrutinized and the hardware challenges were
discussed (Hosseini et al 2019)
The potential gain from the UAV-assisted data gathering was found in
indiscriminate IoTs The characteristic propagation was represented by utilizing the
complicated channel method (contained small- and large-scale fading) IoTs were
updated in constrain of transmit power (in high) and total energy The multi-antenna
UAV was selected in the IoTs in sequence The virtual MIMO was created by the
communication between UAV and singe antenna IoT in every transmission (W
Feng et al 2018)
The UAV was applied in the aerial coverage surveillance agricultural prediction
constructional areas and power line supervising and blood donation The flight
26
period increment payload capability fast movement and speedy placements were
implied features in the UAV so that the UAV was exploited by the applications of
5G and B5G (Ullah et al 2020)
The UAV was considered a motivation for many emergent usages and reformed
social-economic welfares The wireless networks for the UAV and the base stations
were desired for the UAV function Mobile communications were considered
suitable for finding tracing and regulating the flying UAV The wireless
communications were selected for their features of broad coverage quality of
service and secrecy The wireless communication in the UAV improved
productivity besides the line of sight (G Yang et al 2018)
22 UAV-NOMA in Physical Layer Security enhancement
The NOMA has been applied in the fifth generation (5G) technology The Multicast
Cognitive Radio (MCR) network is implemented using the NOMA and coined as
MCR- MOMA The transmission side is also included with the superimposition
code The decoding was applied at the receiving end So an unknown user is
deduced in their methodology (Meng et al 2020)
The physical layer security for the cooperative NOMA was examined Amplify
and forward decode and forward were taken into consideration for achieving
secure transmission (Chen et al 2018)
The physical layer security of the NOMA was analyzed in the broader network with
varying locality The single and multi-antenna were established in the following
cases The single antenna was taken for an end-to-end connection in a secured
manner And the multi-antenna was used for the connection of base station and
random user Finally achieved security for the multi-antenna on the transmission
side The security of the single antenna was attained by introducing the excluding
area for eliminating eavesdroppers The individual expression of security outage
probability for both single antenna and multi-antenna were derived (Yuanwei Liu
et al 2017)
The secure transmission of NOMA in large-scale applications was investigated
Stochastic Geometry was utilized for placing the eavesdropper and user nodes The
equation for secrecy outage probability was derived and expressed for evaluating
27
secure transmission Security can be improved by expanding the protected zone
(Qin et al 2016)
The power domain NOMA had the disadvantage of decoding data by other
unauthentic users of the same source For reducing unauthentic users the base
station should treat the unauthentic users with different cleaning methods The
secrecy outage probability was investigated for authentic users and unauthentic
users Both users were combined as a pair to the non-uniform distribution of original
and unauthentic users The pair outage probability of genuine users from the secrecy
outage probability restrained NOMA authentic users The derivation for pair outage
probability and the secrecy probability were expressed for calibration The
combined system had been the better security (ElHalawany amp Wu 2018)
The physical layer security was considered problematic in the wireless networks
mainly for keeping the authentic userrsquos data The UAV was acted as the base
station UAV based base station had sent the extensive data to the original users
NOMA with the multi-antenna with mm-Wave frequency band transmission had
enhanced the spectral efficiency The physical layer security was attained by
announcing the space around user locality as the eavesdroppers protected zone
Covering the entire eavesdropper area was considered a resource-consuming way
The shape optimization for the protected location in each UAV base stations
altitudes was introduced The derivations for the secrecy sum rate and the secrecy
outage probability were expressed (Rupasinghe et al 2018)
The vehicular communication system had used cooperative NOMA The secrecy
outage probability was considered in vehicular communication The relay can be
used in both modes (half-duplex and full-duplex) in vehicular communication The
closed derivation for the secrecy outage probability was expressed The security of
the full-duplex NOMA resulted better than that of the half-duplex NOMA The
limitations are that the velocity of the vehicles was not considered Figure 21 is
illustrated the conceptual model of the vehicular communication NOMA system
(Xie et al 2019)
28
Figure 21 Vehicular communication NOMA system
The physical layer security of the uplink NOMA of the large-scale devices was
examined The connection networks had investigated with the approach called
stochastic geometry The new derivation was expressed for the coverage
probability The protected zone restrains eavesdroppers to the authentic users
Efficiency secrecy throughput was examined wiretap channels and the many
original users Constant transmission and variable transmission were collectively
inspected The signal to noise and the movement to interference ratio were derived
drastically (Gomez et al 2017)
The wireless system was executed using Space-Time Block Coding (STBC)
approach in the NOMA of mm-Wave MIMO The technique focused on haphazard
users So the pairing method was introduced mainly for Random Near-Random Far
(RNRF) Here the latent period could be minimized and the RNRF has also been
deduced for the overhead issue The result revealed the systems efficiency with a
proper implementation (Ghavidel et al 2020)
The recent arbitrary beam forming method was proposed in the multiple access
NOMA The pairing had decided to the user places So the evaluation was focused
on the system overhead The result revealed that the proposed work outperformed
29
the existing methods (Aghdam et al 2020) NOMA enhances the reliability of
multi-users transmission The sum rate could be reduced for improving Quality of
Service (QoS) power transmission and signal outage probability The
eavesdropper easily accessed the multi-access systems that cause physical security
during transmission (Z Li et al 2020)
The NOMA had provided spectral efficiency speed transmission of data multiple
networking and less latent period The NOMA utilizes the power domains for
various access Cognitive Radio Networks (CRN) is used to screen illegitimate
users The legitimate users were only permitted in the CRN by the Primary User
Networks (PUN) QoS The cooperative NOMA here implemented with the PUN
and the system performance is enhanced The spectral efficiency can be improved
by the secured transmission The cooperative NOMA was additionally developed
in the CRN with the PLS A new method of cooperative NOMA in the CRN was
examined The PUN technique attains a secure transmission Multiple antennae
were used in this study for reliability and the eavesdropperndashexclusion zone method
is used for better security (B Li et al 2018)
The downlink NOMA for moderate CSI was examined The challenge of the power
domain was rectified by allocating power NOMA The power in NOMA and that
of the OMA was analyzed which resulted in a significantly reduced NOMA (Cui
et al 2016)
Here the users were multiplexed by the power domain So the method was coined
as power domain NOMA The demand arising from the B5G (Beyond 5
Generation) had reached using power domain NOMA Machine learning in the
NOMA was described (Maraqa et al 2020)
The uplink NOMA with the PLS was proposed The uplink NOMA contained a
single base station and multi-users a couple of users combined for NOMA The
known jammer emitted the pseudo-noise to divert the eavesdroppers The study had
suggested the two jammers in the uplink NOMA for secure transmission (N Zhao
et al 2020)
The Intelligent Reflecting Surface (IRS) is designed using downlink NOMA The
multi-access had used the space direction of the beams of closure users The IRS
30
had performed the multi-access for every spatial order by the cell edge users of the
orthogonal beams (Ding amp Poor 2020)
The multi-input single-output NOMA has introduced the technique called Secrecy
Beam Forming (SBF) SBF had utilized the artificial noise for NOMA security
aided users in which the eavesdropperrsquos channels deteriorated The SBFs secure
transmission can be achieved in which high successive interference cancellation is
gained (L Lv et al 2018)
The superposition coding was performed in the transmission pat The successive
interference cancellation was conducted in the receiving position These two
techniques were combined in the novel 5G aided NOMA The basic concepts of
uplink and downlink NOMA were mentioned The dominant condition was
performed in the two user clusters of NOMA The prevailing state had issued the
confirmed spectral efficiency gain in NOMA (Tabassum et al 2016)
The relay scheme in IoT was examined for the secrecy of NOMA This was coined
as relay selection NOMA The base station had transmitted the secret messages to
the two NOMA-aided sensors and eavesdroppers IoT had treated the sensors and
eavesdroppers with different power allocations The expression for certain outage
probability and the strictly positive secure capacity was derived Increasing the
number of the relay would enhance the security in the NOMA-aided IoT The
outage probability for NOMA and OMA were compared The NOMA resulted in
better outage probability in Decode and forward mode (Do et al 2019)
31
Figure 22 RS-NOMA against an external eavesdropper
The NOMA-aided IoT was utilized to fight against the external eavesdropper as
Figure 22 The secured NOMA was proposed The base station sent secret
messages to several authentic destinationsmdashseveral eavesdroppers and unauthentic
users
Nakagami-m fading model was carried out using the multiple antennae in the
channel The security was attained using the max-min transmit antenna selection
scheme Both authentic and unauthentic eavesdroppers were analyzed The closed
derivation for the cumulative distribution of the original user was expressed first
That was compared with the unauthentic user The derivation for the secrecy outage
probability was obtained to identify the level of secrecy performance (Lei et al
2018)
Reconfigurable intelligent surface (RIS) aided NOMA was established for the
secrecy performance The main disadvantage of this model was the chance of using
RIS by the eavesdropper The secret outage probability was derived in this paper
The RIS improved the secrecy of the traditional NOMA The eavesdroppers were
limited from receiving the RIS signal by enhancing the number of intelligent
elements in the RIS A high signal-to-noise ratio was obtained from this experiment
(Liang Yang amp Yuan 2020)
32
The cooperative relaying NOMA was proposed for improving private transmission
in wireless networks Full duplex mode transmitted the jamming signals That
received the required communication at first Secondly the jamming signal
emission was sent by the base station The power allocation for the jamming signal
and information signal was decided on the eavesdropper channel state information
The eavesdropper was jammed by the signal from the first phase with maximum
power Second the derivation of the secrecy outage probability was expressed by
static eavesdropper CSI (Y Cao et al 2020)
The NOMA achieved spectral efficiency and secrecy The security of the multi-
NOMA users was obtained by the successive interference cancellation (SIC)
decoding in the receiving node The conservation of the untrusted NOMA was
concentrated in this study The security can be confirmed by the properly secured
decode processing and allocating power The decoding scheme was implemented
for aiding NOMA users The decoding was performed for enhancing the sum-rate
(Thapar et al 2020) The cognitive radio network in NOMA with the external
eavesdropper was proposed (Mehr et al 2020)
The cooperative NOMA was used in the field of energy harvesting communication
The novel relaying technique was introduced for achieving secrecy The secrecy
outage probability was derived and the derivation was expressed for the three
conditions The first condition was the derivation of CSI with a passive
eavesdropper The second condition was the derivation of CSI with the unauthentic
eavesdropper The third condition was the derivation obtained from the multi-relay
nodes The increased SNR resulted in high security The increase in the number of
users deduced security This was considered a disadvantage (Salem et al 2020)
Satellite communication covered more range of broadcasting So the security
challenge was considered a big difficulty in satellite communication Downlink
NOMA was assessed with an eavesdropper for the examination of secrecy The
paper concentrated on the physical layer security of downlink satellites Here two
methods were proposed The frequency-domain NOMA was considered for gaining
spectral efficiency The multiple user interferences were obtained in the process of
overlapping Introducing a suitable technique can be performed the security for the
number of users The secrecy rate was analyzed for all authentic users (and the
33
eavesdropper) and expressed in the derivation The safety was improved using the
spectral overlap method (Yin et al 2019)
The NOMA was considered as the emerging scheme in the upcoming wireless
networks The secrecy sum rate for the downlink NOMA (with MIMO multiple
inputs multiple outputs) was examined Downlink NOMA had the base station
number of users and the eavesdropper In the limitation of transmit power and
optimal successive interference cancellation the security was expected to enhance
Downlink MIMO NOMA was considered advantageous because of its secrecy
performance and the practical usage of bandwidth The mutual information rate and
the mean square error were causing the secrecy rate optimization to the problem of
biconvex This was rectified through the alternative optimization method and the
second-order cone programming was solved (Tian et al 2017)
Table 21 Comparative analysis
The comparative analysis for the physical layer security was examined in existing
studies
SR
No
Details of Author wise Contribution to NOMA Technology
1 Author (YFeng Yang amp Yan 2017) Secrecy performance in NOMA was
conducted with the help of artificial noise in the full-duplex mode of relaying
Methodology The optimization of the power was calibrated for the source
information and the noise signal The closed derivation for the secrecy outage
probability was expressed
Usage and limitations The physical security was increased
34
2 Author (He Liu Yang amp Lau 2017) NOMA was developed in the constrain
of security
Methodology The secret message had been sent to some users and also to the
eavesdropper The Novel decoding process was conducted for excluding the
unauthentic users The iterative algorithm was used for power optimization
Usage and limitations Transmit power was reduced The quality of service
was availed
3 Author (D Wang et al 2020) The secrecy was performed in the NOMA
The security was developed against the eavesdropper outside
Methodology The channel state information was analyzed for secrecy The
quantization of CSI had performed for secrecy The derivation for the secrecy
and transmission outage probabilities were obtained
Usage and limitations The secrecy rate was enhanced
4 Author (L Lv et al 2020) The physical security of the NOMA was
improved by adding artificial noise jammer and inter-user interference The
mode of full-duplex in the updated version was used in the NOMA
Methodology The eavesdropper can be trapped the superimposed signal from
the source So the secrecy was affected
Usage and limitations The spectrum usage is effective in the NOMA
transmission scheme Numerous connections can be performed in the NOMA
NOMA is considered to be the most advantageous for the upcoming
generation communications The superimposition technique was followed
4 Author (Yue et al 2020) Secrecy performance of the NOMA was developed
with a unique framework
Methodology The eavesdroppers inside the zone and outside the coverage
zone were examined properly in this paper The outage probability for codendash
power domain NOMA was derived
Usage and limitations Safety was acquired for both internal eavesdropper
and external eavesdropper in this scheme
35
5 Author (Guezouli et al 2020) The heterogeneous sensor network of cellular
communication was taken into account
Methodology Unmanned aerial vehicles are utilized the heterogeneous
sensor network of cellular communication
Usage and limitations Extended the life span of the network system The
cost of the hardware components is drastically low The random and the
repeats in the speedy movement The latency is maximized The coverage
period is maximum
6 Author (Yao amp Xu 2019) The security in transmitting a large amount of
information in the wireless network systems are analyzed with unmanned
aerial vehicle UAV
Methodology The numbers of UAVs are arranged in the space The base
station sent the information to the UAV in the space The authentic receivers
have obtained the secured information from the UAV The HPPP
homogeneous Poisson point process is used for distributing the authentic
receiver and eavesdropper in the line of sight
Usage and limitations The increase in the number of safety zone causing the
secured transmission
7 Author (Saacutenchez et al 2020) Physical security can be achieved by the
method of a unique encryption scheme
Methodology The physical layer security of the following schemes is
discussed in this paper mm-wave NOMA massive multi-input multi-output
heterogeneous sensor networks full-duplex mode
Usage and limitations The physical layer security was analyzed for the 5G
supporting technologies Good reliability achieved The less latent obtained
Machine-type communications can be enabled
36
8 Author (Hou et al 2018) The multi-antennas were used in NOMA with
UAV The stochastic geometric approach was examined
Methodology The multi-input multi-output kind of NOMA was utilized In
common the stochastic geometric approach was used for drastically moving
NOMA
Usage and limitations The maximum signal-to-noise ratio was obtained in
this scheme Power optimization was achieved The path loss is less Good
spectral efficiency was obtained
9 Author (Miao et al 2020) The broadcast type of communication was
performed The less weighed three-dimensional space for 5G communication
was analyzed
Methodology Both the performances of multicast and broadcast were
enabled UAV-assisted 5G communication systems are emerging in the
upcoming wireless networks
Usage and limitations Better flexibility in the network Continuous mobility
One lined line of sight
10 Author (Majhi amp Mitra 2020) The secure communication in cognitive radio
by NOMA was propounded
Methodology The antenna strategy of giving minimum outage probability
was concluded from this study
Usage and limitations The limitation is that more spectral efficiency causes
security issues
11 Author (X Zhao amp Sun 2020) Secure communication of the physical layer
in Visible light NOMA Communication was proposed
Methodology Energy optimization in security constrain was propounded for
achieving overall performance
Usage and limitations It is difficult to find optimal results because energy
optimization is the nonconvex issue
37
12 Author (Tuan amp Hong 2020) Secure communication in simultaneous
wireless information and power transfer NOMA was remitted
Methodology Eavesdropper is used for security purposes between the user
and base station using energy relays Known jammer is used for secure
transmission For energy efficiency storing and transferring were propounded
Usage and limitations Jamming requires extra power allocation
13 Author (Vaezi et al 2019) NOMA for 5G in mmWave MIMO cooperative
and cognitive were analyzed in this study
Methodology SWIFT NOMA is useful for weak receivers
MIMO using more antenna
Usage and limitations multi-antenna utilization cause high power
consumption
14 Author (Vaezi et al 2019) Mobile edge computing NOMA was proposed to
optimize power
Methodology Minimum latency and less power consumption
Usage and limitations Transfer power allocation must be calibrated
15 Author (Faraji-Biregani amp Fotohi 2020) Security in UAV communication
was proposed by introducing mobile agents
Methodology Malicious user of UAV was identified
Usage and limitations Three-phase power is essential
16 Author (G Zhang et al 2019) Secure communication in 5G UAV was
propounded by joint trajectory carrying out in physical layer
Methodology Power optimization was proposed for security
Usage and limitations Security in the physical layer was achieved by
optimization of trajectory
17 Author (Fotohi et al 2020) Agent-based self-protection was propounded in
UAN for secure communication
Methodology This method imitates the immune system of human beings
Less cost
Usage and limitations Energy is not optimized properly This approach
needs to consider other malicious attackers
38
18 Author (Shang Liu Ma amp Fan 2019) Vehicle to everything approach was
propounded for security in a UAV
Methodology Security of vehicle to the vehicle was proposed by considering
eavesdroppers active and passive attacks
Usage and limitations High price
19 Author (Kantor et al 2017) The flight path was calibrated in a UAV
Methodology Security performance was achieved by encryption as well as
anonymization
Usage and limitations High in cost and hardware structure occupies more
place
23 Research Methodology
The NOMA-based cellular architecture for UAV communication has been
considered here as reference network architecture Rayleigh fading has been
assumed as a channel characteristic The performance parameters for PHY layer
security are (1) Pair Outage probability (Pair OP) between two users trusted near
user designated as U1 and untrusted far user designated as U2) and (02) Secrecy
Outage Probability (SOP) of trusted near user designated as U1 The aim is to
achieve optimal Pair OP for the given constrained SOP of User U1 so that network
resources can be efficiently allocated to both users without compromising the
secrecy of trusted User U1
The mathematical analysis from reference literature (ElHalawany et al 2018) has
verified and supported the joint optimization of the Pair OP and SOP for the given
power allocation factor in NOMA This research work is extended as providing
more efficient resource allocation using the POMDP algorithm in a given scenario
First the varying distance of untrusted user U2 from BS as a critical selection
parameter that affects Pair OP amp SOP of user U1 and U2 both has been simulated
and the feasible and infeasible pairing of both users have been analyzed The
optimal power allocation factor for feasible pairing as the constrained problem is
optimized by opting for POMDP as a resource allocation algorithm wherein the
SOP of user U1 is strictly maintained for given CSI POMDP provides optimum
39
power allocation factor for trusted and untrusted users pairing as shown in the
proposed flow of POMDP algorithm is used to model a variety of real-world
sequential decision-making problems After the BS has been set up the distance
between the BS and the user is calculated and if space is less than 200m it is
defined as a trusted user While if the range is more than 200m it is described as
untrusted users In the case of trusted users the channel state information (CSI) is
provided to the proposed algorithm POMDP for reliable and efficient resource
allocation
24 Summary
UAVs play a central role in providing network service recovery in a disaster-
stricken region enhancing public safety networks or handling other emergencies
when Ultra-Reliable Low-Latency Communication is required In particular UAV-
assisted communication can be regarded as an important complement to the 5G
cellular networks Surveyed literature related to UAV communications published
over the past several years emphasized the cybersecurity and channel modeling for
UAV communications etc Security is one of the critical issues in communications
Modern communication networks are based on the layered architecture from the
physical layer up to the application layer A great deal of effort has been made to
develop the cryptographic protocols above the physical layer However the
physical layer is not as robust as that in wired communications The physical layer
in wireless communication is more complex than the counterpart in other
communication paradigms The concerns come from not only the noises but also
many types of fading Recently there has been an influential interest in studying
the security issues in the physical layer Security is highlighted as another
challenge and the implementation of physical layer security techniques is seen as
a difficult task PHY security in NOMA systems under the presence of external
eavesdroppers or untrusted relay nodes Upcoming 5G networks for unpredicted or
crisis (disaster management) the placement of terrestrial substructures is
economically infeasible and challenging due to high operational expenditure as well
as sophisticated and volatile environments
To address such novel issues intelligent heterogeneous architecture by leverage
UAV has been well-thought-out to be a promising novel model For advancing the
40
performance of the UAV 5G communication system physical layer techniques are
of many effects as they have impacted the applications of UAVs Security of
NOMA-based UAV communication network has been scrutinized for optimization
as physical layer security
41
CHAPTER-3
SYSTEM MODEL FOR NOMA-UAV
COMMUNICATION
31 NOMA-UAV System Secured Communication for 5G
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
311 The basic scheme of NOMA
The NOMA system allowed several users to be served simultaneously by the
transmitter To transfer a linear combination of different signals towards the
recipient the system of proportional representation superposition coding (SC) The
transformed signal is provided through
σ ඥ119875119896 119878119896119870119896 =1 -------------------------------------- (1)
Where 119927119948 represents the transmit power assigned toward user k th
119930119948 indicates the normalized message used for user k th
42
The instantaneous total converses power is σ 119927119948119922119948=1 The received signal at user kth
and the eavesdropper are offered through
119910119896 = ℎ119896 σ ඥ119875119896 119878119896119870119896=1 + 119899119896 -------------------------- (2)
119910119890 = ℎ119890 σ ඥ119875119896 119878119896119870119896=1 + 119899119890 -------------------------- (3)
Where 119951119948 and 119951119942 indicated the zero-mean Additive White Gaussian Noise
(AWGN) at user k th with variance 1205901198962 and the zero mean AWGN at eavesdropper
with variance 1206481199422 respectively We assume that the noise variances at all the users
are identical
ie 12059012 = ⋯ = 120590119896
2 = 1205901198902
As per NOMAs process the SIC is followed by all users to decrypt the message to
the same decoding order Notice that it is not known what the optimal decoding
order is for the NOMA method that corresponds to secrecy
Therefore the mth message to be encoded to the user might not be the mth message
to the user As such we also have to add the π variable For example if 120587(1) =
3 then the first message to be decoded for the SIC is the message for the user 120645(119947)
forall j lt k before decoding its letter to remove the inter-user interference successively
Then the user 120645(119948) denotes its message while treating the news for all the user
120645(119946)foralli gt k as the interferences The received Signal-to-interference-plus ndashnoise
ratio (SINRs) at user 120587(119896) k lt K and user 120587(119870) to decode their messages are
respectively given by
119878119868119873119877120587119896=
120574120587(119896)119875120587(119896)
1+120574120587(119896) σ 119875120587(119894)119896119894=119896+1
119896 lt 119870 --------------------(4)
119878119868119873119877120587119870= 120574120587(119870)119875120587(119870) --------------------------------------(5)
Were 120574120587(119896) =หℎ120587(119896)ห
2
1205901199062
൘
43
Also the acknowledged SINR at user 120587(119898) to decrypt the message 120633120645(119948) 119896 lt
119898 le 119870 is given by
119878119868119873119877120587119896=
120574120587(119898)119875120587(119896)
1+120574120587(119898) σ 119875120587(119894)119896119894=119896+1
kltmle 119870 --------------(6)
Similarly the acknowledged SINRs by the eavesdropper of the message 120575119896 119896 lt
119870 and the message 120575119896 are respectively given by
119878119868119873119877120587macr
119896=
120574119890119875120587(119896)
1+120574119890 σ 119875120587(119894)119896119894=119896+1
klt119870 ----------------- ------(7)
119878119868119873119877120587macr
119896=
ȁℎ119890ȁ2119875120587(119896)
1205901198902 = 120574119890119875120587(119896) klt119870 ---------------------(8)
Where 120574119890=ȁℎ119890ȁ2
1205901198902൘
Notice that here expressions for the obtained SINRs at eavesdropper overestimate
the skill of eavesdropper Here a worst-case inference from the viewpoint of
legitimate users is made That is the messages have already been decrypted by the
eavesdropper for all users π (j) forall j lt k before attempting to decrypt the message
for the user π (k)
The presumption also assumes that the decrypting order and power distribution are
understood by the eavesdropper The eavesdropper may or may not recognize the
decoding order of the users and the allocation of power may or may not recognize
the messages for all users π (j) forall j lt k before attempting to decode messages for
users π (k) However since the eavesdropper has been unable to alert the authorized
customers of its capacity and the current CSI the approved user would be unable
to know the eavesdroppers details Therefore we have to pursue the worst-case
scenario for the permissible users point of view due to the liberality required by the
safety reports It highlights that the worst-case assumption in the study and design
of transmission schemes with secrecy requirements has been generally adopted
The proposed study has been evaluated using performance measures Here we
analyze NOMA with downlink and uplink networks suggested by SINR and Sum
44
Rate survey High SNR is then simulated to contrast the OMA and NOMA
processes
312 Downlink of NOMA
The Downlink of the NOMA network on the transmitter side is described in Figure
31 SIC method is supposed to be carried out successively on the receiver side of
each user until another signal is restored The coefficients of users are owed in an
inversely proportional manner based on their available bandwidth
Figure 31 Downlink NOMA network
A consumer with a poor available bandwidth has a transmission capacity of a
higher range than a consumer with strong available bandwidth As a consequence
the consumer with the higher power assumes the signals of other users to be noisy
and automatically restores the signal without conducting any SIC operation The
receiver of each consumer detects indications that are stronger than those of the
desired signal These impulses are then deducted from the power and this process
continues until the signal has been calculated Both users decrypt their signaling by
considering other users with lower correlations The signal is calculated as
45
119904 = σ 119886119894119875119904119883119894119871119894=1 -----------------------------------------------(1)
Where Xi is the user ithrsquos information through unit energy
Ps is the capacity of transmission at the BS
ti is the coefficient of power assigned for user i
Although without the need for lack of generality the channel profits are expected
to be graded as ȁℎ1ȁ2 le ȁℎ2ȁ2 le ⋯ ȁℎ119871ȁ2
Where 119945119923 is the coefficient of the channel of the user Lth
The received signal of the Lth user is calculated as
1199101 = ℎ119897119904 + 119899119897 = ℎ119897 σ ξ119886119894119875119904119883119894119871119894=1 + 119899119897 -----------------------------(2)
Where n1 is zero mean Complex Gaussian noise with a variance of 1206482SINR
analysis with the equation (2) the SNR of Lth user to identify the user 119895 le 1with
119895 ne 1
119878119868119873119877119871 = 1198861120574 ȁℎ1ȁ2120574ȁℎ1ȁ2൘ σ 119886119894 + 1119871
119894=119871+1 ------------------------(3)
Where 120632 = 1198751199041205902ൗ represents the SNR
Sum rate analysis After identifying the SINR of the downlink the sum rate will
also be done quickly
The NOMAs downlink data rate of Lth user can be calculated as
1198771119873119874119872119860minus119889 = 1198971199001198922(1 + 119878119868119873119877119871) --------------------(4)
313 Uplink of NOMA
The Uplink NOMA is depicted in Figure 32 where each user sends a signal to the
BS SIC iterations are supported to classify the signals of mobile users If both
channels are identical and BS sends the coefficients of power allocation to mobile
users the received signal can be interpreted as a synchronous uplink to the NOMA
46
119955 = σ ℎ119894ඥ119886119894119875119909119894119871119894=1 +n ----------------------------------(5)
Where hi is the coefficient of the channel for the ith user
119927119961119946 is the extreme transmission capacity supposed to be general to all users
N is zero-mean Gaussian noise with a variance of 1206482
Figure 32 Uplink NOMA
Analysis of SINR The BS decrypts the signals of the users as per the coefficients
of the users and the SINR for the Lth user can be defined as
119878119868119873119877119871 = 119886119897120574ȁℎ119897ȁ2120574 σ 119886119894ȁℎ119894ȁ2 + 1119897minus1
119894=1൘ ----------------------------(6)
Where 120574 = 1198751205902ൗ indicates SNR
Analysis of Sum rate The sum rate of uplink NOMA when 120632 minus infin can be
computed as
119877119904119906119898119873119874119872119860minus119906 asymp 1198971199001198922(120574 σ ȁℎ119897ȁ119871
119894=1 2 ------------------------ (7)
47
314 Comparison of NOMA and OMA
The attainable data rate of the Lth user of OMA intended for both uplink as well as
the downlink is estimated as
119877119904119906119898119874119872119860 = σ 120572 1198971199001198922120574(1 +
120573119897ȁℎ119897ȁ2
120572119897119871119894=1 ) --------------------------(8)
Just for convenience two users should evaluate the summation of uplink rates for
NOMA and OMA The use of both the uplink rate of NOMA and OMA at high
SNR can be calculated as---
119877119904119906119898119873119874119872119860 asymp 1198971199001198922(120574 ȁℎ1ȁ2 + 120574ȁℎ2ȁ2 ------------------------- (9)
equation (7) and (8) it is seen that 119877119904119906119898119874119872119860 le 119877119904119906119898
119873119874119872119860
Here we note 119929119956119958119950119926119924119912 le 119929119956119958119950
119925119926119924119912 shows that NOMA performed better than OMA in
terms of sum rate in both downlinks as well as uplink of two user networks
The sum rate will be calculated after the SNR as the formulation is shown In this
proposed work multiple users are propagated to the process of NOMA and here a
comparison of NOMA as well OMA has been defined The NOMA uplink and
downlink using the OFDMA method for the
32 PLS performance metrics in NOMA -UAV communication
This chapter mainly describes the proposed work to examine the availability of the
outage probability of the pair below an authorized user According to the decryption
of SIC availability and spectrum sharing the unauthorized user can function as an
eavesdropper and obtain an outage probability (OP) for all situations with the
Secrecy Outage Probability (SOP)
321 SOP and OP - two user and multi-user NOMA system
NOMA system has the capability for assigning multiple data over the transmission
signal through high-level coding (Shim amp An 2018) Thus it contains spectrum
efficiency when opposed to OMA But this has a limitation in security As an
48
instance if the eavesdropper is reached then it obtains multiple user data in the
interference of the NOMA signal Thus the security issues are more significant in
this system Here PLS is an available method to rectify the attack intended for
malicious users (Dai et al 2015)
Additionally data should be transmitted confidentially if the root and eavesdropper
networks can be evaluated and the recipient can decrypt the received text At the
same time the eavesdropper is not able to solve the text that has been interrupted
PLS is at the cutting edge of wireless communication security technology to prevent
eavesdropping attacks The SOP is described as the likelihood that the near users
attainable device confidentiality capability will fall under the predefined target
confidentiality rate as set out in (Shim et al 2017)
Through SOP we can calculate the level of protection of the device As an example
the low-secret OP system makes the system more stable in terms of security than
the high SOP system To boost the efficiency of the PLS CSI-based opportunistic
scheduling links to a scheduled destination in a particular time slot It has been
documented as an enticing scheduling scheme (Long Yang et al 2016) because the
various wireless channel has been exploited Opportunistic scheduling is also
considered to be one of the strategies used to increase the confidentiality efficiency
of the NOMA method
322 System Model
Suppose a multi-user NOMA system of downlink containing BS a selection of K
nearer users as N= 119873119894ȁ12 119870 and a range of M far users as F=
119865119895ȁ12 119872 and an eavesdropper E as displayed in Figure 33 More
specifically nearer users should make active use of the SIC methodology to
distinguish far user F Both the legitimate and illegitimate receivers are furnished
through a single antenna and operate in a half-duplex manner
49
Figure 33 Multi-two user architecture of NOMA system (Shim amp An 2018)
Here 119945119935119936 and ȁ119945119935119936ȁ2
Where X120598ሼ119878ሽ 119884120598119873 cup ሼ119864ሽ represent the channel coefficient and the corresponding
channel gain of the X-Y value
Taking into consideration that each wireless channel for Rayleigh block fading 119945119935119936
can be incorporated as an independently distributed random Gaussian variable with
zero mean and affirmative ℷ119935119936 Variance The outcome of channel gain ȁ119945119935119936ȁ2is an
exponential variable randomly through the Probability Density Function (PDF)
119891ȁℎ119883119884ȁ2(119911) = ቀ1
ℷ119883119884ൗ ቁ 119890119909119901 (minus 119911
ℷ119883119884ൗ )
if zge 0 119900119905ℎ119890119903119908119894119904119890119891ȁℎ119883119884ȁ2(119911) = 0 -----------------(1)
Especially the average channel profit can be represented as
ℷ119883119884= ൬119889119883119884
1198890൘ ൰
minus휀
ℒ ------------------(2)
When 120027 is the attenuation of the received signal 119941119935119936 signifies the distance among
X and Y 1199410 indicates the space and 120656 is the exponent of the path loss It is believed
that the source is entirely familiar with the CSI of both legitimate users and
eavesdroppers
50
323 Partially Observable Markov Decision Process-POMDP
Figure 34 Flow Diagram of the proposed system
The proposed overflow is shown in Figure 34 After the BS has been set up the
distance between the BS and the user is calculated and if space is less than 200m
it is defined as a trusted user While if the range is more than 200m it is described
as untrusted users In the event of untrusted users the channel state information is
accessible to the POMDP accompanied by the allocation of resources The study
was carried out after the machine operation Here a NOMA-oriented cellular setup
provided with a BS at the Centre and two users was described in Figure 35
51
Figure 35 Near and Far User
The adjacent user has a high level of security confirmation needed to protect the
layer since the low-security clearance user is situated at a distance away from the
BS P is specified as the highest level of transmitting power In this chapter it is
presumed that all DNS servers are furnished utilizing an individual antenna and all
channels are supposed to be individually static identical to the Rayleigh
dissemination concerning distribution
119862119873(0 120575119898
minus120572
212059601 2Τ
)
In which 120633119950 is the range between the BS and the nodes 119932119950 Here the path-loss
exponent and constant are defined as 120630 and 1206540 Furthermore BS is assumed to
have predicted the position of the user so that a better CSI can be obtained at BS
that is elaborate in user pairing
The BS transmits the superimposed mixture
119909119905 = ඥ1199051199041 + ඥ1 minus 1199051199042 ------------------------------- (3)
In which 1199561 and 1199562 are the unit of power signals received by users 1199321 and 1199322
respectively t is the power allocation coefficient for the adjacent user
1199031 = ℎ1119909119905ξ119875 + 1198991 ------------------------------- (4)
1199032 = ℎ2119909119905ξ119875 + 1198992 ----------------------------------(5)
Where 1199451119886119899119889 1199452 the channel profit link with the fading of small scale since the
BS to the user 1199321 and 1199322 respectively The additional Gaussian noise with variance
52
is denoted 1199511 119886119899119889 1199512 and zero mean 119894119904 119889119890119899119900119905119890119889119886119904 (1199250) and it is assumed
that the BS conveyed SNR is 120646 = 1199271199250
ൗ
In the NOMA technique additional users with more power may decode their signal
by recognizing the adjacent signal as noise without decoding the adjacent user
message In the previous equation 1198801 is supposed to first solve a weak signal by
decoding its own SIC signal1198802 which is an unauthenticated user attempted to
decrypt the nearer user text after decrypting the adjacent usage text after decoding
its own SIC message The following equation has therefore been achieved
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2 ----------------(6)
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2 ----------------(7)
119879119900119905119886119897119904119894119899119903 = 11987811986811987311987721 1198781198681198731198771
1 119878119868119873119877221198781198681198731198771
2 -----------------(8)
Where 119930119920119925119929119950119951
indicates the SINR ratio of user mth that was decoded by 119932119951 for
119898 119899 isin ሼ119894 2ሽ and the channels gain followed an exponential distribution with the
parameter 120649119950=120654120782120633119950minus120630
324 Problem formulation
As a result the BS could achieve and provide better communication for users who
are vulnerable to security threats from unauthenticated users the proposed
framework identified two kinds of QoS energy efficiency that could be considered
essential for addressing the problem In a particular study a pair of OPs was
specified to check the reliability at which the attainable data rate for users is equal
to or greater than the threshold of minimum reach The following issue aimed at
reducing the pair OP to an SOP factor intended for the user 119932120783 that is provided by
Where 1199270is Outage Probability- (OP)
1199271 is Secrecy Outage probability user U1 119930119926119927(119932120783) and
120631 the permissible SOP threshold
53
33 Performance Analysis Improving PLS Insecurity of NOMA
System
331 The Pair OP Calculation
Through Shannons capacity formula and assuming 119914120783119957119945 119886119899119889 119914120784
119957119945 as the
threshold capacities of users 119932120783 119886119899119889 119932120784 respectively the combination of OP
could be offered by
119927119954 = 120783 minus 119928120783119961119928120784 in which 120649119950 = 120784119940119950119957119945
119950 isin ሼ119946 120784ሽ -------------(9)
empty120783 =120649120784
120646(120783+119957+120649120784119957) empty120784 =120649120783
120646119957
119928120783 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ 120782 lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 ------------------------(10)
Case 1empty1 gt empty2 for having the limitation of the allocation of power factor (t)
required to be satisfied (tgt120649120783
120649120783+120649120784+120649120783120649120784) and for this case 119928120784 could be attained as
follows
119928120784 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ
120649120783
120649120783+120649120784+120649120783120649120784lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 --------------(11)
Case 2 empty1 lt empty2 Like case 1 it was stated that the opposite constraint depends
on
t gt 1206491
1206491+1206492+12064911206492 and 1199282 can be evaluated as follows
119928120784 = ൝119942119961119953 ቀ
minusempty120784
120649120783ቁ 120782 lt
120649120783
120649120783+120649120784+120649120783120649120784
120782 119952119957119945119942119955119960119946119956119942 ---------------------(12)
54
Table 31 List of parameters
Parameters Description
N Number of nearer users
M Number of far users
E Eavesdropper
ℎ119909119910 Channel coefficient between 119909119905ℎchannel and 119910119905ℎ users
119889119883119884 The distance among x and y
1198890 Space
120598 An exponent of the path loss
ℒ Attenuation of the received signal
120575119898 the range between the BS and the nodes
1205960 Path loss constant
120572 Path loss exponent
1199041 1199042 Unit of power signals received by users 1198801 and 1198802
T Power allocation factor for the adjacent user
ℎ1119886119899119889ℎ2 Channel coefficient of 1198801 and 1198802with the fading of small
scale
11989911198861198991198891198992 Gaussian noise variance
1198730 Zero mean for Gaussian noise
120588 Signal to noise ratio
119878119868119873119877119898119899
Signal to interference noise ratio of users n and m channels
55
120591119898 Exponential distribution parameters
1198750 Pair of OP
1198781198741198751 119878119874119875(1198801)
120573 The permissible SOP threshold
Table 31 depicts the list of parameters used in the proposed methodology which
are useful for assigning and the values are assigned based on the parameters given
for the experimental evaluation as well This chapter concludes with the basic and
the actual flow of the proposed method to know more about the work in the
simulation process
332 Pseudo-code for the proposed algorithm
Algorithm I
Step 1 Estimate Rayleigh distribution
119862119873(0 120575119898minus120572 2Τ
1205961199001 2Τ
) where
120633119950 is the distance between nodes 119932119950 and the BS
120630 is the path-loss exponent and
120654119952 is the path-loss constant
Step 2 The BS broadcasts the superimposed mixture and input signal as follows
119909119905 = ξ1199051199041 + ξ1 minus 1199051199042
Where 119956120783 and 119956120784 are the unit power signals received by users 119932120783 and 119932120784
respectively 119957 is the Power allocation coefficient for the near user
Step 3 The received signal is as follows
1199031 = ℎ1119909119905ξ119875 + 1198991
1199032 = ℎ2119909119905ξ119875 + 1198992 where
56
119945120783 and 119945120784 are the channel gain associated with the
small-scale fading from the BS to users 119932120783 and 119932120784 respectively
1199511 and 1199512 are the additive white Gaussian noise with zero mean and variance
119925120782
Step 4 the BS transmit signal-to-noise ratio (SNR)
120646 = 119927119925120782
Step 5 Signal-to-Interference-plus-Noise-Ratio (SINR) for the two users 119932120783
decodes the signal of the weak user first then decodes its own signal after using
SIC 119932120784 is an untrusted user and tries to decode the near user message after
decoding its own message using SIC
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588ൗ and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ2ȁ2+1120588ൗ and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2
119879119900119905119886119897119904119894119899119903 = ሼ11987811986811987311987721 1198781198681198731198771
1 11987811986811987311987722 1198781198681198731198771
2ሽ
where 119930119920119925119929119950119951
is the signal-to-interference-plus-noise-ratio (SINR)
of user 119950th decoded by 119932119951 for 119898 119899120598ሼ119894 2ሽ and ȁ119945119950ȁ2 is the
channels gain of 119932119950
Algorithm II
Partially observable Markov decision process
Step 1 Prediction of the maximum capacity of channel with respect to the data rate
119955119943 = 119877(119878119909119863)
S is denoted as states
Let D be the channel characteristics which are considering here as actions
Reward function R
Step 2 The agent receives an observation 119900120598120118which depends on the new state of
the environment 119930prime and on the just taken action 119941 with probability
119926(119952ȁ119956prime 119941)
Step 3 Reward earned at time t is expressed as
57
119903119891119905 = 119877(119878119909119863)119905
Step 4 reward function on belief states
119919 is the belief states over POMDP states
119919119943 is the belief state transition function
119955119943 = 119877(119867119909119863)
Step 5 The reward function is updated based on the belief MDP the agent only
cares about which action will yield the largest expected immediate reward ie the
maximum capacity channel
119861119891 ቀℎ 119889 ℎprimeቁ = 119875119903 (
119900120598120118
ℎprimeȁℎ 119889 119900) 119875119903(119900ȁ119889 ℎ) 119861119891
119875119903(ℎprimeȁℎ 119889 119900) = ቄ1119894119891119905ℎ119890119887119890119897119894119890119891119906119901119889119886119905119890119908119894119905ℎ119886119903119892119906119898119890119899119905119904ℎ 119889 119900119903119890119905119906119903119899119904ℎprime
0119900119905ℎ119890119903119908119894119904119890
119903119891(ℎ 119889) = σ ℎ(119904)119877(119904 119889)119904isin119878
34 SUMMARY
The NOMA-UAV communication framework has been proposed in this research
work and the Physical Layer security aspect has been focused on for optimization
The PLS performance metrics selected are SOP amp Pair OP in the proposed system
model The POMDP framework is general enough to model a variety of real-world
sequential decision-making problems Applications include robot navigation
problems machine maintenance and planning under uncertainty in general Here
we have adopted the User pairing POMDP algorithm for resource allocation in two
users amp multi-user NOMA-UAV communication networks The proposed study has
been evaluated using performance measures by varying distances of trusted amp
untrusted users from the base station as well as for varying SINR conditions The
simulation results and outcomes are discussed in a further chapter
58
CHAPTER 4
RESULT AND DISCUSSION
41 PERFORMANCE MEASURES OF SECURED NOMA-
UAV COMMUNICATION MODEL
Drones or UAV-based communication technology has been thoroughly studied and
adopted by the 3GPP standard UAV systems have been envisaged to form an
integral part of future wireless communication applications due to their dynamic
flexible and flying nature Due to their ability to reach higher altitudes they usually
have dominant LOS channels with the ground nodes This capability can be used to
provide confidentiality to the legitimate receivers against the eavesdroppers This
can be done by deploying UAVs to launch more effective jamming signal attacks
to terrestrial eavesdroppers The conventional cooperative jamming schemes make
an assumption that the locations of terrestrial jammers are fixed which might
compromise the secrecy of the system if the jammers are located far away from the
eavesdroppers and is also not practical as it makes an assumption of perfect CSI of
the jammer to eavesdropper channel
Here in the proposed scenario of the NOMA-UAV communication network two
key PHY layer security metrics SOP amp Pair Outage Probability have been jointly
optimized for a more effective power allocation factor for NOMA cellular
architecture The varying channel characteristics have been analyzed to achieve the
desired SOP with the constrained threshold minimum target secrecy rate for the
two-user scenario POMDP Algorithm iteratively provides the optimized SINR that
has been used to keep trusted users in pair with the untrusted user with minimum
achievable outage probability
The proposed NOMA-UAV System model has been simulated in MATLAB 2019b
version with mainly Communications System Toolbox Optimization Toolbox RF
Toolbox Signal Processing Toolbox Statistics and Machine Learning Toolbox
The simulation has been carried out for two-user pair to achieve desired secrecy
target rate and feasible pairing between trusted user amp untrusted user(eves-dropper)
59
The optimal-outage performance of minimized pair OP subjected to SOP constraint
has been solved by both dynamic programming optimization and POMDP
optimization approaches
The simulation of the proposed framework for the UAV-NOMA communication
network has been carried out and discussed in two parts two user models and a
multi-user model as below mentioned discussion The base station is deployed at
the center of a cell of radius 1000 m There are two users in the system under
consideration The channel between two nodes in the system suffers both the small-
scale fading and path loss effect Small-scale fading follows the exponential
distribution with the mean value 1 The noise signal of all channels has a Gaussian
distribution with 0 mean and variance 1 The path loss exponent α and the path loss
constant PLo are set to 2 and 01 respectively We assume a normalized bandwidth
of 1 Hz The SOP constraint threshold is assumed 01 and the target secrecy rate is
001 The power allocation coefficient is 015 and the BS transmitted SINR is
assumed 15dB for the proposed model As per the NOMA transmission scheme
SINR has been obtained for User 1 amp User 2 both for SIC decoding POMDP
algorithm optimally tunes the SINR value for User 1 amp User 2 that is considered to
select optimal power allocation coefficient for both trusted and untrusted users with
respective SOP of User1
42 Numerical results and Discussion
Table 41 Simulation Parameters
Parameters Values
Untrusted user Distance (d2) 200-1000 (300 700)
BS transmit signal-to-noise ratio (SNR) (120588) in dB 15
Sop constraint constant threshold (β) 01
Power allocation factor (t) 015
Trusted User distance (d1) 2-
60
Cell Radius (rd) 1000 meters
Path loss exponent (α) 2
Path loss constant (PLo) 01
Normalized bandwidth in Hz 1
Target secrecy rate (Rs) 001
No of Bits 100
Pair Outage Probability (P0) 05250
SINR 5319 15305 5162
10247
421 Feasible amp Infeasible pairing of trusted amp Untrusted users
In this section the CSI value broadcasted by Base Station is assumed 15 dB initially
and for varying channel conditions various SINR values of 120646 = minus20 minus10 20 dB
is described with target secrecy rate 0005 and 001 for power allocation coefficient
015 and User 1 distance at 200m is shown in the Figure 41 below
Figure 41 Impact on Sop with increase distance between BS and user U2
61
Varying target secrecy rate threshold from 0005 to 001 the obtained result in
Figure 42 revealed that the 1199321 is a gradually reducing function for the distance of
untrusted user d2 that implies that the increasing value of d2 leads to the
improvement of the SOP of 1198801
Figure42 Impact on Sop with increase distance between BS and user U2
Since the offered constant threshold 120656 in SOP limit1199322 which should be located at
a larger space when compared with a value of threshold to attain the SOP of 1199321
apart from that it is expected the high target secrecy rate maximizes the SOP of 1199321
Here in below figure the power allocation coefficient has been varied from 0 to 1
with threshold value of t and the desired t_sop for feasible pairing
Figure 43 Feasible pairing t Vs pair OP
62
Pair OP in case of rising 1199322 untrusted user in d2 for different BS transfer the SNR
where t= 015 and d1=200mThe infeasible pairing of SOP (1199321) and the OP pair
by the enhanced allocation of the power (t) d1 (200m) d2 (300m) 120646 = 15 dB and
120656 = 0
Figure 44 shows the identical plotting of data by adjusting the unauthenticated
level of the user through converting it to a BS closer distance (d2=300m) Accuracy
is compared and checked with the full spectrum of numerical simulations The
result has shown that the effectiveness is based on a comparative study of the two
consumers of the BS
Figure 44 Infeasible pairing t Vs pair OP
422 The Secrecy Outage Probability amp Pair Outage Probability
Feasible paring in the SOP of pair OP and 1199321 with the improved power allocation
factor t in which d2=700m d1=200m 120646 = 15119889119861 and The result described that
the OP and SOP of the user 1199321 with increased for two various distances of the 1199322
untrusted user The simulation result approves the convex nature 120656 = 0 1of the OP
and the SOP is sequentially decreased depending on t Generally when it enhances
the power owed to the weak user text reduces that develop the ability of 1198802 for
discerning the superior positioned signals therefore enhancing the SOP of 1198801
63
Figure 45 Secrecy outage probability
Figure 46 Pair outage probability
423 SNR versus Strictly Positive Secrecy Rate
Figure 47 proved that the potential for confidentiality is superior to the existing
techniques The proposed application for pre-coding improves the efficiency of the
device The transmission power of the system is the power needed for the
transmission of particular data
64
Figure 47 SNR versus Strictly positive secrecy rate
If there is a growth in the number of users there is a risk of inference in the
transmission of data and thus the reliability of the data rate may be affected Based
on these cases the efficiency of the antenna power to be withheld and occupy the
data determined
424 Power radiated by per MMBs antenna
In the case of multi-users scenario when there are more than two users then the
allocation of an optimized resource block to all users is the key parameter to achieve
desired outage efficiency because strong users require higher SNR for higher data
rates and weak users are allocated minimum threshold SNR for lower data rate
requirements to maintain suitable pairing OP and SOP balance
Figure 48 Power radiated by per MMBs antenna
65
So the POMDP policy optimization has shown better performance over the
dynamic programming approach particularly when more users are active (a greater
number of antennas as in Figure 48 the overall radiated power per BS antenna in
downlink has been considerably reduced
43 CONCLUSION AND SCOPE OF FUTURE WORK
431 Conclusion
Starting with LTE (4G) OFDMA has replaced WCDMA with mobile cellular
communications and will also be used during advanced 5G while Non-Orthogonal
Multiple Access (NOMA) has recently been recognized as a groundbreaking PHY
technology in UAV communication NOMA scheme is used in place to increase the
effective use of small resources such as in UAV communication where the data rate
is very low and critical decision making is of utmost importance
The critical need for UAV communication is a secure PHY layer for mission-
critical applications and as NOMA doesnrsquot promise high security the proposed
research work has been carried out to enhance the insecurities of NOMA-UAV
communication In this proposed research work the probabilities of confidential
outage (SOP) and OP were investigated in the two-user NOMA system Here BS is
required to pair a trusted or permissible user with other untrusted users due to the
unequal distribution of untrusted and trusted users in the cell The SIC is then
applied to the receiver side intended for decoding the message signals The Pair OP
of both users has been analyzed for varying Target Secrecy Rate (Rs) of the trusted
user U1 which provides constraint threshold of the SOP of U1
By varying the distance of Untrusted users from BS the optimal distance and power
allocation factor for the feasible pairing of trusted and untrusted users without
compromising the secrecy outage probability of U1 has been achieved in simulation
results
POMDP has provided the optimal power allocation as a resource allocation
algorithm in the dynamically changing environment of two user NOMA cases
where the distance between BS and untrusted user varies significantly The
performance of secure NOMA-UAV is affected critically by (SOP of User 1) which
66
should be optimally selected to maintain the proposed Pair OP between both users
and the simulation results have supported this optimal outage performance Thus
NOMA-UAV architecture has the potential of providing a secure PHY layer for
mission-critical applications by opting for suitable decision-making resource
algorithm POMDP
431 Scope of Future Work
Furthermore the multiuser scenario with the increased number of Untrusted users
can be analytically verified and simulated in the same direction for NOMA-UAV
communication to improve transmission security and reliability In addition more
adaptive and efficient Resource allocation algorithms for NOMA-UAV networks
with secured performance in real-time applications should be investigated
1
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Kantor I Srivastava A N Pasko D M Batla H amp Ubhi G (2017) Secure
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11
PUBLICATIONS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495449|P a g e
Migration from 4g LTE to Advanced PHY Techniques for
Unmanned Aerial Vehicle (UAV) Communication
Pankaj Patel PHD StudentGujarat Technological UniversityGujarat India
ABSTRACT
UAV (unmanned aerial vehicles) with their high mobility and low cost have found a wide range of applications
during the past few decades Historically UAVs have been primarily used in the military mainly deployed in
hostile territory to reduce pilot losses With continuous cost reduction and device miniaturization small UAVs
are now more easily accessible to the public hence numerous new applications in the civilian and commercial
domains have emerged For the sake of boosting resilience against faults natural disasters and unexpected
traffic the Unmanned Aerial Vehicle (UAV) assisted wireless communication systems can provide a unique
opportunity to cater for such demands in a timely fashion without relying on the overly-engineered cellular
network However for UAV-assisted communication issues of capacity coverage and energy efficiency are
considered of paramount importance Starting with LTE (4G) Orthogonal Frequency Division Multiple Access
(OFDMA) has replaced WCDMA for cellular mobile communications and it will also be employed in advanced
5G yet Non-orthogonal multiple access (NOMA) has been recently recognized as a promising PHY technique
to significantly improve the spectral efficiency of mobile communication networks In this paper we provide an
overview of UAV-aided wireless communications by introducing the basic networking architecture
highlighting the key design considerations as well as the new opportunities to be exploited
Keywords LTE (4G) Non-orthogonal multiple access (NOMA) Unmanned Aerial Vehicle (UAV) Wireless
communication
----------------------------------------------------------------------------------------------------------------------------- ---------
Date Of Submission 26-04-2019 Date Of Acceptance 06-05-2019
----------------------------------------------------------------------------------------------------------------------------- ----------
I INTRODUCTION The use of unmanned aerial vehicles
(UAVs) will grow rapidly in the next decade These
remotely piloted or preprogrammed aircraft are
envisioned for applications in numerous civil
settings including industrial monitoring scientific
data gathering agriculture public safety and search
and rescue Many other applications - presently
unforeseen - will inevitably also arise These
vehicles also known as the unfortunate misnomer of
drones must be integrated into the national
airspace system and into the airspace worldwide A
natural concern in the use of UAV is safety and this
has direct implications for the control and non-
payload communication systems that must be used
to operate it efficiently Similarly navigation and
surveillance functions must be made more reliable
and more accurate Because of these factors many
UAV research development testing and
standardization efforts are underway by
governments industries and academia Despite the
fact that piloted civil aircraft have been flying safely
for decades UAV presents distinct new challenges
in the form of different flight profiles eg low-
elevation flights and more high-dynamic maneuvers
wider required bandwidths eg for video and
different ground site characteristics such as locations
in cluttered areas and lower elevation antennas
In this paper first the evolution of radio
technologies considered in UAV wireless
communication is reviewed in literature survey and
the significant work in the area is highlighted along
with the newest challenges The reminder of this
paper is organized as follows
The promising technology NOMA and its
variants are discussed in section three In Section
four the system model and assumptions are
presented and in section five the comparative
analysis of NOMA with existing popular technology
OFDMA (OMA) is given with simulation
persormance analysis At last the work is concluded
in section five
II LITERATURE SURVEY Drones variously known as unmanned
aerial vehicles (UAVs) unmanned aerial systems
(UAS) or remotely piloted aircraft system (RPAS)
are used in several parts of the world for surveying
and aerial mapping disaster management work
monitoring crop production and infrastructure
activities besides commercial photography and
courier delivery The viability of UAV as a
multipurpose research vehiclehas driven great
RESEARCH ARTICLE OPEN ACCESS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495450|P a g e
interest since recent decades[1] The
basictechnology building blocks responsible for the
current advancesinclude airframes propulsion
systems payloadssafety or protection systems
launch and recovery dataprocessor ground control
station navigation and guidanceand autonomous
flight controllers The following briefsurvey is
focused on the area of navigation guidance
andcontrol of UAVs Various control design for
UAVs has beenproposed ranging from linear to
nonlinear synthesis timeinvariant to parameter
varying and conventional PID tointelligent control
approaches The developed controllershave been
implemented for different aerial platforms
airship(blimp) fixed-wing UAV small scale
helicopteruad-rotors and MAV Wireless
communication systems that include unmanned
aerial vehicles promise to provide cost-effective
wireless connectivity for devices without
infrastructure coverage Compared to terrestrial
communications or those based on high-altitude
platforms on-demand wireless systems with low-
altitude UAVs are in general faster to deploy more
flexibly reconfigured and likely to have better
communication channels due to the presence of
short-range line-of-sight links However the
utilization of highly mobile and energy-constrained
UAVs for wireless communications also introduces
many new challenges In India for the regulation
and safety purpose in commercial and survilence
applications the policy guideliens also introduced
as below
Table 1UAV communication Policy Guidelines for
commercial and surveillance purpose
III MIGRATION FROM 4G LTE TO 5G The fruitful deployment of UAV based
communicationsystems for 4G and beyond future
wireless networks is highlyinvolved in finding joint
solutions to challenge of ubiquitousconnectivity with
both a multitude of devices in a spectralefficient way
as well as with energy-efficient transmissionand
operation of the UAV-BS for maximized and
armonizedcoverage and capacity [2][3] It should be
noted that suitableenergy efficiency for the UAV-
assisted ommunication systemachieves paramount
importance in the overall performance ofthe system
Efficient energy consumption results in
enhancedairtime for the communication system
improving bitsJoulesfor a given energy level
Furthermore coverage and capacityof an aerial cell
are attributed to many factors such as
thetransmission power antenna gains UAV
altitude deploymentenvironment and prominently
radio access technology [4]
4G is the fourth generation of broadband
cellular network technology succeeding 3G and
besides the popular techniques in 3G4G ie
TDMAWCDMAOFDMA a new radio access
technology NOMA is also developed by researchers
to be used in communication networks due to its
capability in increasing the system capacity
Recently non-orthogonality based system designs
are developed to be used in communication
networks and have gained significant attention of
researchers Hence multiple access (MA) techniques
can now be fundamentally categorized as orthogonal
multiple access (OMA) and non-orthogonal
multiple access (NOMA) In OMA each user can
exploit orthogonalcommunication resources either
within a specific time slot frequency band or code in
order to avoid multiple access interference The
previous generations of networks have employed
OMA schemes such as frequency division multiple
access (FDMA) of first generation (1G)time
division multiple access (TDMA) of 2G code
division multiple access (CDMA) of 3G and
orthogonal frequency division multiple access
(OFDMA) of 4G
In NOMA multiple userscan utilize non-
orthogonal resources concurrently by yielding a high
spectral efficiency while allowing some degree of
multiple access interference at receivers Recently
NOMA reputations have climbedsharply as a
fundamental solution to the challenges
encompassingthe next generation wireless networks
[5][6]NOMA has been proved to exhibit improved
spectral efficiencybalanced and air access as
compared to OMAtechnologies[6] with the ability
to cater for multipledevices in the same frequency
time or code resource thusproviding efficient access
to massive connected devices Furthermore NOMA
is also instrumental in reducingthe interference by
employing orthogonal resources as inOrthogonal
Frequency Division Multiple Access
(OFDMA)[7][17] or by sharing a single beam
between multiple users forintra-cluster access and
using NOMA for inter-cluster access[18]Current
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495451|P a g e
studies have focused on provisioning Air to
Ground(A2G) communication services mainly
through placement op- timization under various
viewpoints in literature The performance of UAV
based communication systems hasalso been
addressed for the underlaid Device to Device(D2D)
deployment scenario This work assumed
interferenceraised by D2D network nodes without
considering the presenceof terrestrial BS
Additionally there have been a fewstudies
discussing the performance of NOMA for UAV
basedcommunication system[8] A NOMA enabled
fixedwingUAV deployment was proposed in [8] to
support coveragefor ground users situated outside
BS offloaded location
In general NOMA schemes can be
classified into two types power-domain
multiplexing andcode-domain multiplexing In
power-domain multiplexing different users are
allocated[7][8][9][6][5][1][10] differentpower
coefficients according to their channel conditions in
order to achieve a high systemperformance In
particular multiple usersrsquo information signals are
superimposed at the transmitterside At the receiver
side successive interference cancellation (SIC) is
applied for decoding thesignals one by one until the
desired userrsquos signal is obtained providing a good
trade-offbetween the throughput of the system and
the user fairness In code-domain multiplexing
different users are allocated different codes and
multiplexed over the same time-frequencyresources
such as multi-user shared access (MUSA) sparse
code multiple access (SCMA) and low-density
spreading (LDS) In addition to power-domain
multiplexing and codedomain multiplexing there are
other NOMA schemes such as pattern division
multiple access(PDMA) and bit division
multiplexing (BDM) Although code-domain
multiplexinghas a potential to enhance spectral
efficiency it requires a high transmission bandwidth
andis not easily applicable to the current systems
On the other hand power-domain multiplexinghas a
simple implementation as considerable changes are
not required on the existing networksAlso it does
not require additional bandwidth in order to improve
spectral efficiency Inthis paper the prime focusis on
the power-domain NOMAAlthough OMA
techniques can achieve a good system performance
even with simple receiversbecause of no mutual
interference among users in an ideal setting they
still do not have theability to address the emerging
challenges due to the increasing demands in future
networks andbeyond
The superiority of NOMA over OMA can
besummarized as follows
_ Spectral efficiency and throughput In OMA such
as in OFDMA a specific frequencyresource is
assigned to each user even it experiences a good or
bad channel conditionthus the overall system suffers
from low spectral efficiency and throughput In
contrary inNOMA the same frequency resource is
assigned to multiple mobile users with good and
bad channel conditions at the same time Hence the
resource assigned for the weak user isalso used by
the strong user and the interference can be mitigated
through SIC processesat usersrsquo receivers Therefore
the probability of having improved spectral
efficiency and ahigh throughput will be considerably
increased
_ User fairness low latency and massive
connectivity In OMA for example in OFDMAwith
scheduling the user with a good channel condition
has a higher priority to be servedwhile the user with
a bad channel condition has to wait to access which
leads to a fairnessproblem and high latency This
approach cannot support massive connectivity
HoweverNOMA can serve multiple users with
different channel conditions simultaneously
thereforeit can provide improved user fairness lower
latency and higher massive connectivity
_ Compatibility NOMA is also compatible
with the current and future communication
systemssince it does not require significant
modifications on the existing architecture For
exampleNOMA has been included in third
generation partnership project long-term
evolutionadvanced (3GPP LTE Release 13)
Figure 1Pictorial comparison of NOMA Vs OMA
Although NOMA has many features that
may support next generationsit has some limitations
that should be addressed in order to exploit its full
advantage set Thoselimitations can be pointed out
as follows In NOMA since each user requires to
decode thesignals of some users before decoding its
own signal the receiver computational
complexitywill be increased when compared to
OMA leading to a longer delay Moreover
informationof channel gains of all users should be
fed back to the base station (BS) but this results in
asignificant channel state information (CSI)
feedback overhead Furthermore if any errors
occurduring SIC processes at any user then the error
probability of successive decoding will beincreased
As a result the number of users should be reduced to
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495452|P a g e
avoid such error propagationAnother reason for
restricting the number of users is that considerable
channel gain differencesamong users with different
channel conditions are needed to have a better
network performance
IV NOMA UPLINK AND DOWNLINK
SCENERIO SIMULATION ANALYSIS In this section an overview of NOMA in
downlink and uplink networks is introduced
throughsignal-to-interference-and-noise ratio (SINR)
and sum rate analyses Then high signal-to-
noiseratio (SNR) analysis has been conducted in
order to compare the performances of OMA
andNOMA techniques[10]
A Downlink NOMA Network
At the transmitter side of downlink NOMA
network as shown in Fig 2 the BS transmits
thecombined signal which is a superposition of the
desired signals of multiple users with different
allocated power coefficients to all mobile users At
the receiver of each user SIC process isassumed to
be performed successively until userrsquos signal is
recovered Power coefficients ofusers are allocated
according to their channel conditions in an inversely
proportional mannerThe user with a bad channel
condition is allocated higher transmission power
than the one which has a good channel condition
Thus since the user with the highest transmission
power considers the signals of other users as noise
and recovers its signal immediately without
performing anySIC process However other users
need to perform SIC processes In SIC each userrsquos
receiverfirst detects the signals that are stronger than
its own desired signal Next those signals
aresubtracted from the received signal and this
process continues until the related userrsquos own signal
is determined Finally each user decodes its own
signal by treating other users with lower
powercoefficients as noise The transmitted signal at
the BS can be written as
s = aiPsxi
L
i=1
where xi is the information of user i (Ui)
with unit energy Ps is the transmission power atthe
BS and ai is the power coefficient allocated for user
i subjected to ai = 1Li=1 and a1gea2gehellip geaL since
without loss of generality the channel gains are
assumed to be ordered as h1 2 le h2 2 le⋯ hL 2 where hL is the channel coefficient of Lth
user based on NOMAconcept The received signal
at lth user can be expressed as follows
y1 = hls + nl = hl aiPsxi + nlL
i=1
where nlis zero mean complex additive Gaussian
noise with a variance of σ2
(1) SINR analysis By using (2) the instantaneous
SINR of the lth user to detect the jth user jle l
with jne L can be written as
SINRl = alγ hl 2
γ hl 2 aiLi=l+1 + 1
Where γ = Psσ2 denotes the SNR
(2) Sum rate analysis After finding the SINR
expressions of downlink NOMA the sumrate
analysis can easily be done The downlink
NOMA achievable data rate of lth user can
beexpressed as
RlNOMA-d
= log2 1 + SINRl = log2(1 +alγhl2γhl2 i=l+1Lai+1
B Uplink NOMA Network
In uplink NOMA network as depicted in
Fig 3 each mobile user transmits its signal to the
BS At the BS SIC iterations are carried out in order
to detect the signals of mobile users By assuming
that downlink and uplink channels are reciprocal and
the BS transmits power allocation coefficients to
mobile users the received signal at the BS for
synchronous uplink NOMA can be expressed as
r = hi aiPxi + n
L
i=1
where hi is the channel coefficient of the ith
user Pxi is the maximum transmission power
assumed to be common for all users and n is zero
mean complex additive Gaussian noise with a
variance of σ2
Figure 2Downlink NOMA network
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495453|P a g e
Figure 3 Uplink NOMA network
1) SINR analysis The BS decodes the signals of
users orderly according to power coefficientsof
users and then the SINR for lth user l ne 1 can
be given by
SINRl =alγ hl 2
γ ai hi 2 + 1lminus1i=1
where γ =P
σ2
2) Sum rate analysis The sum rate of uplink
NOMA when γ minus infincan be written as
Rsum NOMA-u asymp log2(γ hl 2L
l=1
C Comparing NOMA and OMA
The achievable data rate of the lth user of OMA for
both uplink and downlink can be expressed
RsumOMA = αl log2(1 +
βlγ hl 2
αl)L
l=1
For the sake of simplicity sum rates of
uplink NOMA and OMA can be compared for
twousers Then using both the sum rate of uplink
NOMA and OMA at high SNR can beexpressed
respectively as
RsumNOMAasymp log2 γ h1 2 + γ h2 2
Here we notice ROMA
sumle RNOMA
sum
Fig shows that NOMA outperforms OMA in terms
of sum rate in both downlink and uplinkof two
user networks
V SIMULATION RESULTS
The Comparative analysis of modelling
Downlink and Uplink NOMA in comparison with
OMA is simulated and findings are presented that
shows superiority of NOMA over OMA with better
spectral efficiency for simulation parameters taken
as power allocation coefficients a1=06 a2=04 and
channel responses h1 2
=0 DB h22=20 DB
parameters
Figure 4NOMA UPLINK
Figure 5 NOMA DOWNLINK
VI CONCLUSION This paper investigated an account of
NOMArsquos applicability for UAV-assisted
communication systems NOMA schemes are
proposed to improve the efficient usage of limited
network sources OMA based approaches that use
time frequency or code domain in an orthogonal
manner cannot effectively utilize radio resources
limiting the number of users that can be served
simultaneously In order to overcome such
drawbacks and to increase the multiple access
efficiency NOMA technique has been recently
proposed Accordingly users are separated in the
power domain Such a power domain based multiple
access scheme provides effective throughput
improvements depending on the channel conditions
The crucial need of UAV communication of
optimum utilization of available licensed spectrum
bandwidth is considered here and simulation results
taken presented that NOMA performs better than
OMA while fulfilling individual user-rate constraint
for both users The research work can be further
carried out investigating joint power and phase
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495454|P a g e
allocation of UAV nodes deployment for efficient
operations
REFERENCES [1] S M I C Y L M I Muhammad Farhan Sohail
Non-Orthogonal Multiple Access for Unmanned
Aerial Vehicle Assisted Communication in IEEE
access 2018
[2] M Mozaffari Drone small cells in the clouds
Design deployment and performance analysis in
IEEE Global Communications Conference 2015
[3] R Z a T J L Y Zeng Wireless
communications with unmanned aerial vehicles
opportunities and challenges in IEEE
communication magazine 2016
[4] I B-Y a H Yanikomeroglu The new frontier in
ran heterogeneity Multi-tier drone-cells IEEE
Communications Magazine pp 48-55 2016
[5] P K S a D I Kim Uav-enabled downlink
wireless system with NOMA access in IEEE
Globecom Workshops Dec 2017
[6] P Xu and K Cumanan Optimal power allocation
scheme for nonorthogonal multiple access with
fairness in IEEE Journal on Selected Areas in
Communications oct 2017
[7] E H a D I K S Ali Non-orthogonal multiple
access (noma) for downlink multiuser mimo
systems User clustering beamforming and power
allocation in IEEE Access 2017
[8] W S M B a M D M Mozaffari Unmanned
aerial vehicle with underlaid device-to-device
communications Performance tradeoffs in IEEE
Transactions on Wireless Communications June
2016
[9] Z D X D a R Z Z Chen An optimization
perspective of the superiority of noma compared to
conventional oma in IEEE Transactions on
Signal Processing Oct 2017
[10] M T Mahmoud Aldababsa1 and S G G K 2 A
Tutorial on Non-Orthogonal Multiple Access
2017
[11] X L Z J W a K J R L Zhu Han Delay
Sensitive Scheduling Schemes for Heterogeneous
QoS over Wireless Networks IEEE
TRANSACTIONS ON WIRELESS
COMMUNICATIONS VOL 6 NO 2
FEBRUARY 2007 vol 6 no 2 2007
[12] Z J W a K J R L Z Han A resource
allocation framework with credit system and user
autonomy over heterogeneous wireless networks
in IEEE Global Telecommunications Conference
2003
[13] N B S a P S S Chen Heterogeneous delay
tolerant task scheduling and energy management in
the smart grid with renewable energy IEEE
Journal of Selected Areas in Communications vol
31 no 07 pp 1258-1267 july 2013
[14] H L Z C a Z H Y Hu Scheduling strategy for
multimedia IEEE Transactions on Vehicular
Technology July 2016
[15] P F a K B L Y Dong High-speed railway
wireless communications efficiency vs fairness
IEEE Transactions on Vehicular Technology vol
63 no 2 pp 925-930 march 2014
[16] T R a Z H Z Chang Queueing game for
spectrum access in cognitive radio networks
IEEE Communications Letters vol 19 no 11 pp
2017-2020 June 2015
[17] Z C L T R a Z H F I Yun Hu Service
Provisioning and User Association for
Heterogeneous Wireless Railway Networks IEEE
Transactions on Communications 2017
[18] H S W Tianti Chen Optimal Scheduling for
Wireless On-Demand Data Packet Delivery to
High-Speed Trains IEEE Transactions on
Vehicular Technology vol 64 no 9 pp 4101 -
4112 september 2015
Pankaj Patel Migration from 4g LTE to Advanced PHY Techniques for Unmanned Aerial
Vehicle Communication International Journal of Engineering Research and Applications
(IJERA) Vol 09 No04 2019 pp 49-54
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Improving Of Physical Layer Insecurity Of The
Non Orthogonal Multiple Access System
Pankaj M Patel Prof Dr Chetan B Bhatt
Abstract The key aspect of the NOMA (power domain non orthogonal) is the user possibility for decoding the messages belonging to another pair users
on similar resources The method interprets a security threat especially in the case where the base station serves the users with various security
clearance or untrusted users The main aspect of NOMA is to serve the multiple users upon the similar radio resources at the minimal inter user
interference expense The system not only permits the serving of particular users with high efficient bandwidth but also permits the scheduling more type
of users than the timely available users In this study we investigated the secrecy outage probability (SOP) and OP in the both two user and multi user
NOMA system where the BS is supposed to pair a trusted or legitimate user with other untrusted users because of the un even distribution of the
untrusted and trusted users in the cell SIC the successive interference cancellation was then implemented at the receiver side for decoding the
message signals With the application of NOMA concept the study investigated the pair outage behavior under the SOP constraints on the trusted users
In specific the SOP and OP of the concerned U1 were obtained in the closed type of expressions The study also provided the understanding the
possibility of obtaining an optimal outage efficiency for pairing under the SOP constraints With certain numerical simulations the study verified the
effectiveness of the analytical derivations with respect to various scenarios
Index Terms NOMA Secrecy outage Probability Successive Interference Cancellation bandwidth channel state information etc
mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash
1 INTRODUCTION The physical layer security and non-orthogonal multiple
access was regarded as the encouraging techniques for the
processing of wireless communication network systems Today
the combination of the two significant communication methods
was studied to guarantee a spectral efficient and secure
wireless transmission Most of the prevailing works
predominantly concentrated on the optimization and efficiency
of the PLS in the existence of untrusted relay nodes and
external eavesdroppers(Arafa et al 2019a)But there occurs a
gap in the theoretical studies to describe the ease of obtaining
the enhanced efficiency in the existence of untrusted users
Recently the network traffic amount have greatly enhanced
particularly with the updated growth in IoT applications in
future To rectify the huge traffic demand upcoming wireless
networks must deliver a best spectral effectiveness and large
connectivity (Sun et al 2018) NOMA is regarded as the best
technology in which various NOMA technique exhibit similar
concept of providing several users at the similar frequency and
time The famous NOMA types are code domain and power
domain that provided enhanced efficiency when compared
with the existing techniques The paper adopted the power
domain on the basis of super position coding (transmitter side)
at the SIC (receiver side) Hence the users could possess the
key for the messages of other users and thereby utilize SIC for
removing the interference (Cao et al 2019) (Zhao et al
2018) Hence various NOMA methods was proposed for
allowing the adjacent users to perform as a relay for improving
the efficiency of the weak users through the resending of
decoded data in a next time slot The weak user could utilize
the MRC technique to integrate the information achieved in
different time slots In addition obtaining a secured
communication is a crucial problem over the vulnerable
wireless networks to security threats mainly because of the
broadcasted transmission nature
The study investigated the secrecy performance and outage
with the untrusted user(Furqan et al 2019) The main aspect
of the study is to analyze the feasibility of achieving the OP of
the pair under a trusted user Because of the decoding facility
and spectrum sharing of SIC the untrusted user could perform
as a eavesdropper
Figure 1 Representation of Base station
Figure 1 depicts the representation of base station The main
aim of the proposed system defined as
bull To investigate the outage probability of the proposed
system
bull To investigate the SOP of the proposed system
bull To derive the accurate expression of the outage
probability for all kind of scenarios and closed form of
expressions for few special cases and verifying them
numerically for yielding a better outage efficiency
2 RELATED WORKS This section describes the different existing techniques and
methods related as our proposed system (Cao et al
2019)suggested two kinds of relay selection process denoted
as AF (amplify and forward) and DF (decode and forward) on
the basis of AORS and DORS for achieving secure and
reliable NOMA systems under the untrusted users The study
derived the accurate and asymptotic closed form of the SOP
expressions and the PSCP obtained by the two methods and
investigated the optimized feature of the two methods The
____________________________________
bull PANKAJ M PATEL is currently pursuing PHD program in Electronics
amp Communication in Gujarat Technological University E-mail
pankajmphd24gmailcom
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complete analysis and the simulation results represented that
both the AORS and DORS characteristically outperformed the
benchmark system apart from obtaining the similar SOP and
the required PSCP at very high Signal to noise ratio (Zhang et
al 2018)Investigated the power allocation and joint subcarrier
issue for NOMA ndashAF two-way relay networks with restrictions
The study focused to optimize the obtainable secrecy
efficiency by designing jointly the SC task power allocation
and user pair scheduling The paper suggested a SCAS-1
technique by assuming the appropriate information about the
channel state information in the relay station followed by the
formulation of SCAS-2The secured power allocation issue is
structured as a convex programming issue and then resolved
by in-depth point techniques The results of simulation
explained that the efficiency of the suggested SSPA algorithms
with and without CJ respectively (Arafa et al
2019b)Considered a downlink system where the base station
is connecting with two appropriate users in two various
scenarios in the unsecured environments which are the
presence of the eavesdropper and untrusted relay
communication In the first process several trusted
cooperative relays is engaged for assisting with the base
station transmission and protect the corresponding signals
from the eavesdropper Several relay methods are framed and
investigated for the following process which are forward and
decode cooperative jamming and AFFor all the technique
secured beam forming signals were formulated at the relays
for maximizing the obtainable secret rate areas For the next
process with untrusted relay the obtained secrecy rate areas
obtained for two various relay schemes which are AF and CF
under two various operation modes In the first process the
prescribed users will receive the signals from the untrusted
relay and the base station for decoding the messages The
study depicted that the efficient relay scheme is highly
dependent on the parameters of the system especially the
nodal distance and the secrecy rate area (Sun et al
2018)Studied the algorithm for resource allocation for MISO
systems where the full duplex BS serve several half duplex
downlink and uplink users on the similar subcarrier The
allocation of the resource have been optimized for maximizing
the weight system output whereas the leakage of information
was restricted and an artificial noise was induced for granting
secured communication with respect to potential
eavesdroppers The study formulated a novel non-convex
optimization issue by considering the imperfect CSI of the
channels and requirements of QoS of legitimate users The
simulation results stated the efficiency of the optimal algorithm
was related to the suboptimal algorithm Apart from that the
suggested MISO NOMA technique not only guarantee uplink
and downlink communication purpose for security but delivers
a characteristic rate of system secrecy when compared with
the conventional MISO and other two baseline methods
(Dang et al 2017)Analysed the outage efficiency of various
multicarrier relay selection techniques for 2 hop OFDM system
in Poisson relay fields The study concentrated on DF relay
systems with more selection schemes The accurate
expressions for the OP are provided in integrals generally
Apart from that asymptomatic derivatives for OP in the SNR
region in the fixed circle area are predicted for both relay
selection techniques in closed forms Consequently several
significant factors that are linked to the cooperative network
were examined comprising OP ratio of two selection
techniques diversity and subcarrier optimization output In
conclusion a structure to analyze the OP of OFDM with
spatially random relay have been constructed that could be
easily altered for analyzing same case with various forwarding
protocols channel conditions and location distributors (Dang
et al 2018)Proposed a full duplex OFDM ndashD2D system in two
hop network where DF relays help the transmission from DUE
transmitter to DUE receiver The study also investigated the
OP issue by integrating the transmit power within the DUE
relays and transmitter and to deliver a suboptimal solution that
can improve the outage performance The investigations are
validated by Monte Carlo simulations These results described
could furnish an insight into full duplex OFDM system and
guides for the application in the next generation network
(Kokshoorn et al 2016) suggested a robust channel algorithm
for mmWave systems on the basis of novel overlapped pattern
design With the use of finite measurements the study
depicted that this decreased measurements was found ENR of
25 dB to obtain the similar PEEFor the appropriate channel
with quickly altering channel information the price might be
acceptable for improving the speed of estimation The study
also proposed a robust channel estimation algorithm where
the additional calculations are carried out when expecting
more estimation error The study depicted that the channel
could be measured more effectively resulting in noteworthy
gains upto 6 dB when comparing with the existing algorithm
(Ali et al 2016) described the variations in the principles of
downlink and uplink NOMA transmissions in a wireless
system The study formulated a maximization issue in a cell
like the user clustering and power allocations Because of the
integral nature of the formulated programming issue the study
solved the issue in to steps which are grouping of users into
clusters and then to optimize the corresponding power
allocations The study proposed a sub optimal scheme that
exploited the gain variations in NOMA groups and clusters into
multiple and single clusters for enhancing the sum-throughput
The results compared the efficiency of OMA and NOMA in
different network scenarios (Lv et al 2017) investigated a
MCR-NOMA where the multicast user functions as relays to
enhance the efficiency of both secondary and primary
networks On the basis of the available CSI three various
secondary user schedule techniques for processing MCR-
NOMA were depicted For evaluating the system efficiency the
study derived the closed form of expressions of OP and order
of diversity for both the networks It has been described that
more spatial temporal diversity could be obtained by using the
CSI for scheduling of the secondary user (Liu et al 2016)
considered a MIMO ndashNOMA scenario for investigating a
dynamic clustering issue in an logical perspective To resolve
the problem of optimization issue three algorithms named top
down A and B bottom up were suggested for realizing various
complexity tradeoff and worst user throughput The study
noted that the top down B algorithm could obtain a better
tradeoff between throughput and complexity amongst the
applied procedures (Fianu and Davis 2018) investigated
three various rules of allocation and demonstrated the optimal
policy as an available inventory function The study also
provided the country level estimation of requirements that are
not met and the determination of the probability distribution
linked with the total undeserved counties The study have
been done for depicting the policy of allocation with respect to
effectiveness and equity (Hou et al 2018) studied the socio
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graphical impact on the mobile video services and thereby
suggested a CTMDP on the basis of resource allocation
technique by considering social graphs as the constraints
With the use of relative value an optimized policy could be
achieved that aimed at increasing the reward regarding the
average system The simulation depicted that the suggested
CTMDP obtained an increased efficiency against the state of
art methods
3 PROPOSED WORK
Fig 2 Proposed flow depicting the overall mechanism
The proposed(Interference mitigation using POMDP) overall flow
is depicted in the figure 2 After setting up of the base station the
distance between the base station and the user was determined
and if the distance is less than 200 meters it is decided as trusted
users and if it is greater than 200 m it is defined as untrusted
users In case of untrusted users the channel state information is
subjected to POMDP (Partially observable Markov Decision
Process) followed by resource allocation The performance
analysis have been done after the system The work considered
a NOMA oriented cellular setup provided with a base station at
the centre and two users as shown in the figure 2 The adjacent
(near) user possess high level of security clearance that is
required for securing with physical layer from the low
securityuntrusted clearance user (U2) that is located at a faraway
distance from the base station P is defined as the maximum
transmit power level (base station)In this paper it is assumed that
all the network nodes are installed with single antenna and further
all the channels are considered to be identical independently
quasi static with Rayleigh distribution with respect to distribution
119862119873(0 120575 frasl
120596 frasl
) In which 120575 is the distance in-between the BS
and nodes 119880 Here path-loss exponent and path-loss constant is
represented as 120572 and 120596 In addition it is assumed that base
station predicted the user location so that a better CSI is
obtainable at base station that is involved in pairing the users
The base station transmits the superimposed mixture
119909 = radic119905 119904 + radic1 minus 119905 119904
In which 119904 119904 are the unit power signals received by users 119880 and
119880 respectively 119905 is the power
allocation coefficient for the adjacent user
119903 = ℎ 119909 radic119875 + 119899
119903 = ℎ 119909 radic119875 + 119899
where ℎ ℎ - the channel gain linked with the
small-scale fading from the base station to users 119880 and 119880
respectively 119899 and 119899 are the extra white Gaussian noise with
variance and zero mean 1198730 and it is assumed that 120588 = 1198751198730 is
the BS convey signal-to-noise ratio (SNR) In NOMA technique
farther user that possess more power
could decode its own signal by considering the adjacent signal as
a noise without decoding the adjacent user message In the
preceding equation it is assumed that U1 first decode the weak
signal followed by decoding its own signal with SICU2 which is
the untrusted user attempted to decode the near user message
after the decoding of the adjacent user messages after the
process of decoding its own message with SICHence the
following equation have been achieved
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119879119900119905119886119897 = 119878119868119873119877 119878119868119873119877
119878119868119873119877 119878119868119873119877
+
where 119878119868119873119877 represented the signal-to-interference-plus-noise-
ratio of user 119898 that was decoded by 119880 for 119898119899120598119894 2+ and the
channels gain of 119880 denoted by |ℎ |
followed an exponential distribution
with the parameter 120577 = 120596 120575
Problem Formulation
Hence the base station should achieve and serve a better
communication for the users who are susceptible to security
threat from untrusted user the proposed system defined two
kinds of QoS efficiency measures that could be regarded to be
important for framing the issue In specific the study defined a pair
of OP to check the reliability of the QoS satisfaction In general
the pair OP is stated as the probability in which the obtainable
data rates dor the users equal to or greater than the least target
threshold The next metric also called as the SOP is the
probability that the non negative secrecy capacity obtained by the
trusted user is more than the threshold value
The following issue aimed at reducing the pair OP subjected to a
SOP factor for the user U1 that is provided by
min
119875
0 lt 119905 lt 05
119878119874119875 le 120573
in which 119875 119878119874119875 and 120573 are the pair OP SOP(119880 ) and the
permissible SOP threshold
4 PERFORMANCE ANALYSIS
Derivation of the Pair OP
With the use of Shannonrsquos capacity formula and considering
119862 and 119862
as the threshold capacities of users 119880 and
user 119880 respectively the OP of the pair could be provided
by
119875 = 1 minus 119876 119909119876
in which
120591 = 2
119898 120598 119894 2+
120601 =
( )
120601 =
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119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 1 120601 gt 120601
For having 120601 gt 120601 the constraint on
the power allocation factor (t) needs to be satisfied
(119905 gt
) and for this case 119876 could be obtained as
follows
119876 = exp (
)
lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 2 120601 lt 120601
Like case 1 it was stated that opposite constraint on
a as (119905 lt
) and
119876 can be derived as follows
119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
The OP of the NOMA pair
119875 = 1 minus 119891(119905)119896 (119905)
lt 119905 lt
1 minus 119891(119905)119896 (119905) 0 lt 119905 lt
in which
119891(119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
Derivation of SOP of 119880
With Shannonrsquos capacity formula the secrecy rate of
user 119880 was provided by
119878119862 = 119869 minus 119869
119869 = log (1 + 119879119900119905119886119897 (r (1)))
119869 = log (1 + 119879119900119905119886119897 (r (2)))
119878119862 is the non-negative secrecy capacity of 119880 Provided the
secrecy capacity in the SOP of 119880 is
119878119874119875 = 1 minus 120584119890
119860 =
120584 =
119879 - the user 119880 secrecy target rate
Theorem 1
Outage-optimal power allocation factor
119905 = radic
( )
In which 119908 =
119908 =
119911 = 1 + 120591
The minimum power allocation factor (119886 )
119905 =
(
)
The optimal OP of the NOMA pair under the SOP constraint
=
( )
( ( ))119890
( )
That is lt 0whih meant that the U1 (SOP) is a reducing function
Of t that results in the optimal power allocation factor that is
greater than 119905 for the satisfaction of secrecy constraining
factorPartially observable Markov decision process S is
represented as statesLet D is the channel features which is
consider here as actions the conditional transition probability
between states is regarded as T Reward function R is
calculated as the prediction of maximum capacity channel with
respect to data rate r = R(S x D) the agent receives an
observation o ϵ 120118 o isin Ω display style oin Omega that
depended on the new environment state S and on the just
took action d with the probability O(o|s d)
Reward received at time t is conveyed as r = R(S x D)
H is the belief states over POMDP states
119867 is the belief state transition function
119903 = 119877(119867 x 119863) is the reward function on the belief states
119861 (ℎ 119889 ℎ ) = sum Pr ( 120118 ℎ |ℎ 119889 119900) Pr(119900|119889 ℎ)
Pr(h |h d o) =
1 if the belief update with arguments h d o returns h 0 otherwise
The reward function is updated on the basis of the belief MDP
r (h d) = sum h(s) R(s d) isin
the agent focus on the largest expected immediate rewardin
other words the maximum capacity channel The section
analyse the accuracy of the analytical derivations under
various settings
Figure 3 The feasible pairing
The SOP of U1 with the increasing untrusted user U2 and
distance (d2) for several BS transmits Signal to Noise Ratio
at 120588 = minus20minus1020 119889119861is depicted in with a=005 and 01 and
d1=200m is depicted in the figure The results stated that the
U1(SOP) is a gradually reducing function as per d2 that
implies that the increasing value of d2 leads to the
improvement of the SOP of U1 Since the provided constant
threshold ϵ in SOP restraint U2must be situated at a larger
space when compared with threshold value to obtain the SOP
of U1 Apart from that it is normal that the high the target
secrecy rate rises the SOP of U1
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Figure 4 The Secrecy outage probability
Feasible Pairing in th SOP of pair OP and U1 with the
enhanced power allocation factor (a) in which d2 = 700 m d1
= 200 m 120588 = 15 dB and ϵ = 01 The results depicted that the
the pair OP and SOP of user U1 with increased a for two (d2)
various distances of the (U2) untrusted user The results
approve the convex nature of the pair OP and the SOP curve
is gradually decreasing on the basis of a Generally during the
increase in a the power assigned to the weak user message
decreases that minimize the ability of U2 for discriminating the
superior positioned signals thereby improving the SOP of U1
Figure 5 The Pair outage probability
Pair OP in case of rising U2 untrusted user in distance (d2)
for different base station transfer the signal to noise ratio(120588 =
5 15 25 dB) where a = 015 and d1 = 200 m
Figure 6The infeasible pairing of secrecy outage
probability of the pair OP and U1
The infeasible pairing of SOP (U1) and the pair outage
probability with the enhanced allocation of the power ad1(200
m)d2(300 m)120588 = 15dB and ϵ = 0
The figure 6 depicted that the
The figure 6 shows the similar plotting of the data by altering
the untrusted user location by transferring it to a BS closer
distance (d2 = 300 m) It also depicted that the U1 SOP
constraint of is disrupted at a because the SOP is more than ϵ
The accuracy is well-matched and verified with all range of
numerical simulation The results noticed that the efficiency is
based on the comparative locations of the two user with the
base station
Figure 7 The figure 7 depicts that SNR versus strictly
positive secrecy rate
The observed graph proves that the secrecy capacity
outperforms the existing techniques The proposed precoding
application increases the performance of the system The
transmission power of the system is the power required to
transmit a particular data When there is an increase in the
number of users there is the possibility of inference in the data
transmission and hence the efficiency of the data rate may be
affected Depending on these instances the efficiency of the
antenna capacity to withheld and accommodate the data
determined
Figure 8 The power radiated by BS antenna
In the figure 8with respect to the simulation setup the
precoding methods are performed based on the radiated
power per BS antenna is depicted The results observed the
better efficiency of the proposed system The proposed proves
to be better when compared with existing linear precoding
methods in the prescribed three metrics thereby stating that
MRT may be utilized for the the examination of the secrecy
capacity Our proposed technique spends less radiatated
power thereby increasing the overall capacity of the system
5 CONCLUSION The NOMA system decodes the messages of other user pairs
on the similar resources thereby promoting user possibility
The technique interprests a security threat in which the BS
serves the untrusted users The study analysed the SOP and
OP in both multi user and two user NOMA system in which the
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base station pairs the trusted user in closed type of
expressions The proposed (Interference mitigation using
POMDP) also enable the understanding of possibility of
achieving outage optimal efficiency to pair under SOP
constraints The numerical verifications verified the efficiency
of the analytical derivations
6 REFERENCES [1] ALI M S TABASSUM H amp HOSSAIN E 2016
Dynamic user clustering and power allocation for
uplink and downlink non-orthogonal multiple access
(NOMA) systems IEEE access 4 6325-6343
[2] ARAFA A SHIN W VAEZI M amp POOR H V
2019a Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
15 210-222
[3] ARAFA A SHIN W VAEZI M amp POOR H V
2019b Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
[4] CAO K WANG B DING H LI T amp GONG F
2019 Optimal Relay Selection for Secure NOMA
Systems under Untrusted Users IEEE Transactions
on Vehicular Technology
[5] DANG S CHEN G amp COON J P 2018
Multicarrier relay selection for full-duplex relay-
assisted OFDM D2D systems IEEE Transactions on
Vehicular Technology 67 7204-7218
[6] DANG S COON J P amp CHEN G 2017 Outage
performance of two-hop OFDM systems with
spatially random decode-and-forward relays IEEE
Access 5 27514-27524
[7] FIANU S amp DAVIS L B 2018 A Markov decision
process model for equitable distribution of supplies
under uncertainty European Journal of Operational
Research 264 1101-1115
[8] FURQAN H M HAMAMREH J amp ARSLAN H
2019 Physical Layer Security for NOMA
Requirements Merits Challenges and
Recommendations arXiv preprint arXiv190505064
[9] HOU L ZHENG K CHATZIMISIOS P amp FENG Y
2018 A Continuous-Time Markov decision process-
based resource allocation scheme in vehicular cloud
for mobile video services Computer
Communications 118 140-147
[10] KOKSHOORN M CHEN H WANG P LI Y amp
VUCETIC B 2016 Millimeter wave MIMO channel
estimation using overlapped beam patterns and rate
adaptation IEEE Transactions on Signal Processing
65 601-616
[11] LIU Y ELKASHLAN M DING Z amp
KARAGIANNIDIS G K 2016 Fairness of user
clustering in MIMO non-orthogonal multiple access
systems IEEE Communications Letters 20 1465-
1468
[12] LV L CHEN J NI Q amp DING Z 2017 Design of
cooperative non-orthogonal multicast cognitive
multiple access for 5G systems User scheduling and
performance analysis IEEE Transactions on
Communications 65 2641-2656
[13] SUN Y NG D W K ZHU J amp SCHOBER R
2018 Robust and secure resource allocation for full-
duplex MISO multicarrier NOMA systems IEEE
Transactions on Communications 66 4119-4137
[14] ZHANG H YANG N LONG K PAN M
KARAGIANNIDIS G K amp LEUNG V C 2018
Secure communications in NOMA system
Subcarrier assignment and power allocation IEEE
Journal on Selected Areas in Communications 36
1441-1452
[15] ZHAO T LI G ZHANG G amp ZHANG C-X
Security-Enhanced User Pairing for MISO-NOMA
Downlink Transmission 2018 IEEE Global
Communications Conference (GLOBECOM) 2018
IEEE 1-6
CERTIFICATE
I certify that the work incorporated in the thesis lsquoHeterogeneous Wireless Network
using Non-Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo
was submitted by Shri Pankaj Manubhai Patel was carried out by the candidate under
my supervisionguidance To the best of my knowledge (i) the candidate has not
submitted the same research work to any other institution for any degreediploma
Associateship Fellowship or other similar titles (ii) the thesis submitted is a record of
original research work done by the Research Scholar during the period of study under
my supervision and (iii) the thesis represents independent research work on the part of
the Research Scholar
Signature of Supervisor Date 17092021
Name of Supervisor Dr Chetan B Bhatt
Place Ahmedabad
Coursework Completion Certificate
This is to certify that Mr Pankaj Manubhai Patel enrolment No 139997111012 is a
PhD scholar enrolled in the PhD program in the branch Electronics and
communication Engineering of Gujarat Technological University Ahmedabad
(Please tick the relevant option(s))
HeShe has been exempted from the coursework (successfully completed during
the MPhil Course)
HeShe has been exempted from Research Methodology Course only
(successfully completed during the MPhil Course)
HeShe has successfully completed the PhD coursework for the partial
requirement for the award of PhD Degree His Her performance in the
coursework is as follows
Grade Obtained in Research Methodology
(PH001)
Grade Obtained in Self Study Course
(Core Subject)
(PH002)
BC BB
Supervisorrsquos Sign
Name of supervisor Dr Chetan B Bhat
Originality Report Certificate
It is certified that PhD Thesis titled lsquoHeterogeneous Wireless Network using Non-
Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo by Shri
Pankaj Manubhai Patel has been examined by us We undertake the following
a The thesis has significant new workknowledge as compared to already
published or is under consideration to be published elsewhere No sentence
equation diagram table paragraph or section has been copied verbatim from
previous work unless it is placed under quotation marks and duly referenced
b The work presented is original and the own work of the author (ie There is no
plagiarism) No ideas processes results or words of others have been presented
as the Authors own work
c There is no fabrication of data or results which have been compiledanalyzed
d There is no falsification by manipulating research materials equipment or
processes or changing or omitting data or results such that the research is not
accurately represented in the research record
e The thesis has been checked using (copy of originality report attached) and found
within the limits as per GTU Plagiarism Policy and instructions issued from time
to time (ie Permitted similarity index lt=25)
Signature of the Research Scholar Date 17092021
Name of Research Scholar Pankaj Manubhai Patel
Place Ahmedabad
Signature of Supervisor Date 17092021
Name of Supervisor Dr Chetan B Bhatt
Place Ahmedabad
132
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SODH PAPER FOR PLAGRIASMdocxDocument SODH PAPER FOR PLAGRIASMdocx (D47816804)
1
PhD THESIS Non-Exclusive License to
GUJARAT TECHNOLOGICAL UNIVERSITY
In consideration of being a PhD Research Scholar at GTU and in the interests of the
facilitation of research at GTU and elsewhere I Pankaj Manubhai Patel has Enrollment
No139997111012 hereby grants a non-exclusive royalty-free and perpetual license to
GTU on the following terms
a) GTU is permitted to archive reproduce and distribute my thesis in whole or in part
andor my abstract in whole or in part (referred to collectively as the ldquoWorkrdquo) anywhere
in the world for non-commercial purposes in all forms of media
b) GTU is permitted to authorize sub-lease sub-contract or procure any of the acts
mentioned in paragraph (a)
c) GTU is authorized to submit the Work at any National International Library under
the authority of their ldquoThesis Non-Exclusive Licenserdquo
d) The Universal Copyright Notice (copy) shall appear on all copies made under the authority
of this license e) I undertake to submit my thesis through my University to any Library
and Archives Any abstract submitted with the thesis will be considered to form part of
the thesis
f) I represent that my thesis is my original work does not infringe any rights of others
including privacy rights and that I have the right to make the grant conferred by this
nonexclusive license
g) If third party copyrighted material was included in my thesis for which under the terms
of the Copyright Act written permission from the copyright owners is required I have
obtained such permission from the copyright owners to do the acts mentioned in paragraph
(a) above for the full term of copyright protection
h) I retain copyright ownership and moral rights in my thesis and may deal with the
copyright in my thesis in any way consistent with the rights granted by me to my
university in this non-exclusive license
i) I further promise to inform any person to whom I may hereafter assign or license my
copyright in my thesis of the rights granted by me to my university in this non-exclusive
license
j) I am aware of and agree to accept the conditions and regulations of a PhD including
all policy matters related to authorship and plagiarism
Signature of the Research Scholar
Name of Research Scholar Pankaj Manubhai Patel Date 17092021
Place Ahmedabad
Signature of Supervisor
Name of Supervisor Dr Chetan B Bhatt Date 17092021
Place Ahmedabad
Seal
i
ABSTRACT
The landscape of future fifth-generation (5G) radio access networks is
expected to seamlessly and ubiquitously connect everything and
support higher traffic volumes densely connected wireless devices and
diversified requirements on reliability latency battery lifetime etc as
opposed to the current fourth-generation (4G) cellular networks
Moreover in unexpected or emergencies (such as disaster relief and
service recovery) the deployment of terrestrial infrastructures is
economically infeasible and challenging due to high operational
expenditure as well as sophisticated and volatile environments To
address such novel issues intelligent heterogeneous architecture by
leveraging unmanned aerial vehicles (UAVs) (or commonly known as
drones) has been considered to be a promising new paradigm To
improve the system performance of UAV communication in 5G
networks physical layer techniques are of much concern as they affect
the applications of UAVs significantly In this research work security
aspects of NOMA-based UAV communication network have been
considered for optimization as physical layer security in a wireless
communication network is not as robust as wired communication due to
fading and varying SNR scenarios Here primarily two usersrsquo models
as the trusted and untrusted user communicating with BS have been
optimized for outage-optimal performance considering pair Outage
probability and Secrecy outage probability as performance metrics The
achieved results are extended to multi-user scenarios also and for the
optimal policymaking dynamic programming and Partially Observable
Markov Decision Process (POMDP) optimization approaches have
ii
been simulated and verified The simulated results have shown that
POMDP has potential consideration as a resource scheduling
optimization technique in the NOMA-UAV communication network for
providing secure and more robust performance
iii
Acknowledgment
Completing a PhD is a tough task that requires hard work and a lot of effort This is
often an overwhelming but also great experience that I would not have been able to
complete without the assistance and support of so many people Thus it is my great
pleasure to thank all those people First of all I would like to thank almighty for giving
me the strength to carry out this task I would like to deeply thank Dr Chetan B Bhatt
my supervisor for his guidance encouragement and support over these years This
research work would not have been possible without his constructive pieces of advice his
systematic guidance and his patient support thought out the duration of my research work
I would like to express my sincere gratitude to Dr Harshal A ALOORKAR and Dr
KIRAN R TRIVEDI Dr Mehul Raval my doctoral progress committee members Their
rigorous style of reviewing and constructive feedback with valuable suggestions of Dr
Prakash Gajjar Mr Hitesh Panchal and Mrs Monali Mandli who spent their valuable
time whenever required for discussing aspects of this work and provided relevant material
as well Mr Parth Modi and Mr Jagadish Patankar to initiate and inspired me a lot to
continue my work Mr Mukesh Sharma who help in maintain documents I am also
thankful to my parents and family members who always stood with me in each critical
situation and supported me endlessly I am thankful to all EC departments of various
polytechnic and degree engineer colleges for their cooperation in every possible means
Lastly I would thank all the people who directly or indirectly helped me during this very
important phase of my life
Pankaj Manubhai Patel
vi
List of Abbreviation
3GPP 3rd Generation Partnership Project
5G Fifth Generation
A2G Air to Ground
AWGN Additive White Gaussian Noise
BDM Bit Division Multiplexing
BS Base Station
BPCU Bits Per Channel Use
CDMA Code Division Multiple Access
CR Cognitive Radio
CSI Channel State Information
CNPC Control and Non-Payload Communications
CRN Cognitive Radio Networks
D2D Device-to-Device
DCP Difference of Concave Programing
DOMP Dynamic Optimization Method of Programming
FR Floating Relay
GSM Global System for Mobile Communications
HLPSL High-Level Protocol Specification Language
ICT Information and Communication Technology
IoT Internet of Things
IRS Intelligent Reflecting Surface
IMT Information Management Technology
vi
LDS Low-Density Spreading
LTE Long Term Evolution
LTE-A Long Term Evolution Advance
MCR Multicast Cognitive Radio
MI Mobile Internet
MIMO Massive Multiple-Input Multiple-Output
mm-Wave millimeter Wave
MTC Machine-Type Communication
MUSA Multi-User Mutual Access
NOMA Non-Orthogonal Multiple Access
OFDMA Orthogonal Frequency Division Multiple Access
OMA Orthogonal Multiple Access
OP Outage Probability
POMDP Partially Observable Markov Decision Process
PLS Physical Layer Security
PDMA Pattern Division Multiplexing Control
PUN Primary User Networks
QoS Quality of Service
RIS Reconfigurable Intelligent Surface
RNRF Random Near-Random Far
Rs Target Secrecy Rate
SAGIN Space-Air-Ground Integrated Networks
SIC Successive Interference Cancellation
STBC Space-Time Block Coding
vi
SBF Secrecy Beam Forming
SCMA Sparse Code Multiple Access
SOP Secrecy Outage Probability
TAS Transmit Antenna Selection
TDMA Time Division Multiple Access
UAVC Unmanned Aerial Vehicle Communication
UMTS Universal Mobile Telecommunication Systems
URLLC Ultra-Reliable Low Latency Communication
vii
List of Figures
Figure Title Page
No
11 Usage of wireless sensor network and UAV in the
hazardous disaster control
6
12 UAV network applications types with security services
architecture
8
13 UAV-assisted heterogeneous network architecture 12
14 Security problems in the UAV 15
15 Comparative analysis of NOMA vrsquos OMA 18
21 Vehicular communication NOMA system 28
22 RS-NOMA against an external eavesdropper 31
31 Downlink NOMA network 44
32 Uplink NOMA network 46
33 Multi-two user architecture of NOMA system 49
34 Flow Diagram of the proposed system 50
35 Near and Far User 51
41 Impact on Sop with increase distance between BS and user U2 60
42 Impact on Sop with increase distance between BS and user U2 61
43 Feasible pairing t Vs pair OP 61
44 Infeasible pairing t Vs pair OP 62
45 Secrecy outage probability 63
46 Pair outage probability 63
47 SNR versus Strictly positive secrecy rate 64
48 Power radiated by per MMBs antenna 64
viii
List of Tables
Table Title Page
No
11 Physical layer hazards and measures in UAV wireless
communication network
13
21 Comparative analysis 33
31 List of parameters59 54
41 Simulation parameters 59
ix
Table of Content
Sr
No
Title Page
No
I Abstract I
II Acknowledgment II
III List of Abbreviation III
IV List of Figures Iv
V List of tables V
1 Introduction 1
11 Modern technology and its needs 1
111 Long term evolution of 4G network 2
112 Migration from 4G LTE to 5G for UAV communication 3
12 UAV assisted communication in heterogenous sensor network 5
121 Introduction to UAV Communication network 7
122 Tyews of UAVs 8
1221 UAVs as flying BSs 8
1222 UAVs as aerial UBs 10
13 Unmanned aerial vehicle for 5G network 11
14 Physical layer insecurity in UAV communication network 12
141 Principles of security 13
15 Non-Orthogonal Multiple Access (NOMA) system secured
communication
16
151 Comparison of NOMA Vs OMA 16
1511 Spectral throughput and efficiency 17
1512 User fairness and higher lately 17
1513 Compatibility 17
16 Problem identification 18
17 Motivation 19
18 Aim and objective of the research 20
19 Thesis organization 21
2 Literature review 23
x
21 Integration of UAV Networks for 5G and B5G communication 23
22 UAV-NOMA in physical layer security enhancement 26
23 Research methodology 38
24 Summary 39
3 System model for NOMA-UAV communication 41
31 NOMA -UAV system secured communication for 5G 41
311 The basic scheme of NOMA 41
312 Downlink of NOMA 44
313 Uplink of NOMA 46
314 Comparison of NOMA and OMA 47
32 PLS performance metrics in NOMA -UAV communication 47
321 SOP and OP - two user and multi-user NOMA system 48
322 System Model 48
323 Partially Observable Markov Decision Process-POMDP 50
324 Problem formulation 52
33 Performance Analysis Improving PLS Insecurity of NOMA
System
53
331 The pair OP calculation 53
332 Pseudo-code for the proposed algorithm 55
34 Summary 57
4 Result and discussion 58
41 Performance measure of secured NOMA-UAV communication
model
58
42 Numerical result and discussion 59
421 Feasible amp Infeasible pairing of trusted amp untrusted
users
60
422 The secrecy outage probability and pair outage
probability
62
423 SNR versus strictly positive secrecy rate 63
424 Power radiated by per MMBs antenna
64
43 Conclusion and scope of future work 65
431 Conclusion 65
432 Future scope 66
xi
5 References 67
8
Publications 78
1
CHAPTER -1
INTRODUCTION
11 Modern technology and its needs
Mobile technology has undergone various generational shifts transforming the
cellular framework into a worldwide set of interconnected networks In recent days
the fifth generation (5G) has delivered voice as well as video streaming It has a
very complex range of networking services for more than nine billion users and also
billions of devices that will be connected (Hu 2016) However 5G offers a new
outlet for reflection It involves a radial network architecture for the installation of
communication-type machines 5G network can also include powerful support
applications with widely varying operating parameters 5G is a blend of network
technologies that have been developed The new 5G technology will be able to
exchange information anywhere every time for the benefit of people enterprise
and society and technical environments using a restricted access bandwidth to
carry data Now it is more than a modern series of technologies and as opposed to
previous generations would entail tremendous infrastructure or machinery
upgrades This technology aims to expand on the advances that telecommunications
systems have already achieved The projected standards of efficiency that
technologies would need to resolve are
bull Five times reduce end-end latency
bull Ten to a hundred times the higher complex rate of user data
bull Battery life is ten times longer
bull 10 to 100 times higher number of connected devices
In this research work the UAV-assisted communication over the 5G network has
been proposed with enhanced physical layer security aspects NOMA has been
proposed as the reference framework architecture for UAV communication as one
of the recent popular 5G techniques Along with the advantage of suitability in UAV
communication network NOMA has the disadvantage of insecurity in the physical
layer Here the migration of Long Term Evolution (LTE) to advanced physical layer
2
security for Unmanned Aerial Vehicle communication (UAV) over 5G network has
been proposed and also improve the insecurity of Non-Orthogonal Multiple Access
(NOMA) System We will discuss in the further chapter the proposed work This
chapter describes the introduction and basic concepts of the 5G networks with
methodology techniques and types It states the problem identification motivation
and further aim and objective of this work
111 Long Term Evolution of 4G Network
LTE is customary for 4G wireless broadband trends that provide improved network
capability and gives mobile device users speed It offers high peak data transform
rates in the range of 100 Mbps and 30 Mbps downstream and upstream
respectively It provides a capacity of scalable bandwidth mitigated latency and
backward compatibility with the previous Global System for Mobile
Communications (GSM) and Universal Mobile Telecommunication Systems
(UMTS) technology
The fourth development of cellular networks (4G) has already been developed to
meet the standards of the 3G and 2G families Every 10th year a new mobile
generation claimed to be familiarized with the first 1G system in 1981 tracked by
the 2G system that went on to roll out in 1992 and 3G launched in 2001 growth in
the year 2002 of 4G networks The actual new revolution began in December 1998
with the 3rd Generation Partnership Project (3GPP) With high-quality video and
images 3G networks are designed for multimedia networking with them Peoples
communication can also be enhanced and connectivity to public and private
network information and resources has improved with higher frequencies and new
flexible communication features third-party device applications
With the start of LTE-Advanced several vital demands and improvements are
beginning to emerge Various importance purposed for LTE-Advanced can be
exemplified as follows (Abed)
bull Provides spectrum output with LTE delivered more than three times
bull Spectrum can help scalable bandwidth and convergence of the spectrum
where it is necessary to use a non-contiguous range
3
bull Provides uplink and downlink spectrum output that varies between
15bpsHz and 30bpsHz
bull The edge throughput must be twice that of the user cell in LTE
bull From idle status to connected status the communication latency scenario is
smaller than 50msec and less than 5msec for direct packet transfer
bull Any users total throughput must be three times that of LTE
bull LTE advancement will provide 3GPP as well as LTE compatibility via inter
networking
bull The mobility conditions that are used in LTE are identical
The latest LTE advanced requirements are not yet included in device
specifications there are high-level purposes Before it is fixed in the specifications
and needs to be tested much effort remains to be approved
112 Migration from 4G LTE to 5G for UAV communication
The productive implementation of a UAV communication network in 4G and the
upcoming wireless network is included in identifying combined solutions to test
the correlation with both multitudes and also energy-efficient transmission Then
the process of the UAV-BS to optimize coverage and power It is stated that the
energy efficiency of the UAV-aided communication system is needed Efficient
energy utilization contributes to increased air time in the contact system and
increased joulesbits at a provided energy level Also aerial cell coverage and
ability may be because of various parameters such as antenna gains transmission
strength radio access technology UAV altitude and deployment environment
4G is the fourth generation of network infrastructure technologies to replace 3G and
in addition to the popular 3G4G methods Code Division Multiple Access
(CDMA) Time Division Multiple Access (TDMA) and Orthogonal Frequency
Division Multiple Access (OFDMA) Researchers are designing the latest Non-
Orthogonal Multiple Access (NOMA) technologies to be used because of their
capability to improve the performance of communication networks Non-
4
orthogonality-based device designs have recently been developed for use in
communication networks and drawn considerable interest from researchers
Henceforth Multiple Access (MA) methods can be sub-divided as OMA and
NOMA Each user may utilize orthogonal communication resources to determine
multiple access interference inside a frequency band code and time slot in OMA
Its methods such as First generation (1G)- FDMA 2G -TDMA 3G -CDMA and
4G - OFDMA have been used in previous network generations In NOMA by
producing a higher spectral efficiency however enabling some amount of multiple
entree intrusion in receivers and multiple users may use non-orthogonal resources
simultaneously Recently the credibility of NOMA as a solution to the problems of
the next generation of wireless networks has been increased Compared with OMA
technologies NOMA has been described to improve spectral quality be well-
adjusted with air connectivity and can provide accommodations for multiple
strategies at the same time of frequency Therefore enabling excellent progress to
massively correlated devices
In particular NOMA also affects mitigating interference by using OFDMA as an
orthogonal method or through offering a standard intra-cluster access beam across
multiple users and inter-cluster access in NOMA Recent studies have concentrated
primarily on the provision of Air to Ground (A2G) connectivity services through
optimization of a different point of view
The output of the UAV-based communication network was discussed in the Device
to Device (D2D) implementation setup The proposed system hypothesized
interference caused through D2D network nodes deprived of acknowledging the
occurrence of global BS Also several studies addressed the efficiency of NOMA
It permitted the deployment of fixed-wing to assist coverage in-ground user located
outer location of offloaded BS
NOMA systems are divided into two categories namely code domain and power
domain multiplexing In the power domain user accounts are allocated to different
power coefficients as per their channel complaint to reach optimal device
efficiency Multiple user signals are applied to the side of the sender Then on the
received signal Successive Interference Cancellation (SIC) is implemented to
decipher signals in sequential order until the predicted signal is achieved offering
5
a good trade-off between efficiency of the system and user fairness Different code
domain multiplexing is Sparse Code Multiple Access (SCMA) Low-Density
Spreading (LDS) and Multi-User Mutual Access (MUSA) Compared to power and
code domain multiplexing there are alternate NOMA techniques such as Bit
Division Multiplexing (BDM) and Pattern Division Multiplexing Control (PDMA)
However this multiplexing is capable of improving the efficacy of spectral It
requires a large transfer of bandwidth which is not appropriate for new methods
But on the other side the power domain has direct execution since there is no need
for significant improvements to the current networks It also does not necessitate
bandwidth to increase spectral efficiency In this chapter the main emphasis
depends on the power domain NOMA While OMA strategies can produce the best
results also with necessary receivers due to no mutual intervention among users in
an optimal situation they cannot even resolve increasing problems due to growing
demands on connectivity growth and even beyond
12 UAV assisted communication in heterogeneous sensor network
Wireless communications had created a golden chance for urban and rural
territories The LTE (Long term evolution) and LTE-A (Long term evolution
Advance) had offered the service (with QoS) for all customers through wireless
The traffic properties in the machine type communications (MTC) and the
accumulation of the MI (Mobile Internet) had made the difficulty of implementing
the cellular communication networks Installing base stations was impractical in the
urban areas due to its cost To overcome this issue the UAV suggested that it
contains the merits of compatibility and high battery life and is affordable Most of
the devices like the sensor nodes and professional cameras had been used in UAV-
assisted networks Here the UAV-assisted floating relay (FR) was launched in the
cellular communication networks UAVs were implemented more with WSN
(wireless sensor networks) The base stations were adopted with the UAV So the
MI and MTC traffic challenges were controlled (Yue Li amp Cai 2017)
UAV-assisted Heterogeneous networks had implemented in vast practical
applications UAV helped heterogeneous networks were applied in the military
department In the military the UAV had examined and surveyed the opposing
6
countryrsquos activities for security The UAV-based heterogeneous networks were
used in the military sectors where a novel authentication scheme was introduced
As The one-to-one communication via WSN was considered as secured
communication WSN had the disadvantage of consuming power The
authentication was implemented in the tool of Automated Validation
of Internet Security Protocols and Applications (AVISPA) in which the expression
had been written in the High-Level Protocol Specification Language (HLPSL)
programming language The authentication had evaluated between the user and the
base station Similarly the authentication between the user and the UAV was
calibrated The citizen and economic safety are predicted and conserved through
reliable communication in the military by obtaining foes exploration information
The faithful secured communication was confirmed using AVISPA (Rashid et al
2019)
Figure 11 Usage of wireless sensor network and UAV in the hazardous
disaster control
The integration of the wireless sensor networks and the unmanned aerial vehicle
UAV was analyzed and applied to manage the natural disaster illustrated in Figure
11 The aircraft can prevent the fire spreading drop sensors the temperature map
and biodiversity map by sensors the wildfire can easily route The wild animals can
7
be tracked and the dynamic data of moving animals can be gathered by WSNs The
biologists can fix the sensor in the animals collar the radiation that positively
affects humans can be observed in affected areas The WSNs help to prevent heart
attack of a person by monitoring heart rate The state of health can be known
through a message alarm using a GPRS system
The cooperative networks of WSN and UAV were implemented in the military
sector for the advantageous feature The UAV was providing good connections
overlapping and overall data rate The conventional UAV method aided sensor
networks concentrated only on the single tasks of monitoring accumulating
information and localization The multi-UAV had not been implemented in the
sensor networks The animal colony perception technique was utilized for
scheduling the resourced and the target assignment Functions of multi-data were
used for localization by the target recognition method (Gu Su et al 2018)
The Physical Layer Security (PLS) was achieved through 5G technologies delicate
coding for the PLS dense MIMO multi-input multi-output mm-Wave frequency
band using heterogeneous sensor networks NOMA and full-duplex mode of
communication IoT and Machine-type communications (MTC) emerged in the 5G
systems (Wu et al 2018)
121 Introduction to UAV communication network
The usage of the UAV will develop more in the next era These pre-programmed
aircraft are intended for applications in several civil settings as well as industrial
visualization agriculture rescue and search and then receiving of scientific data
These devices are called the unsuccessful inaccuracy of drones which must be
incorporated into the system of national airspace as well as worldwide The usage
of UAVs in the neutral form is always secure It has a direct inference for the control
and a payload communication system that is utilized to function effectively
Similarly surveillance and navigation operations must be made more accurate and
consistent Due to these critical factors many kinds of research in a UAV testing
development and standardization difficulties are undergone through industries
education and governments
8
Even though civil aircraft had been operating for many years yet UAV offers new
consequences in terms of various flight profiles For example high dynamic
maneuvers and low elevation flights need bandwidth video and different ground
site characteristics namely clutter locations and elevation antennas which are low
This chapter explains the core topic of the proposed work The migration of LTE
4G towards the advanced one of the physical layers for UAV communication It has
higher mobility and lower expense identified in a broad range of applications
122 Types of UAVs
The UAVs have a two-network application with security services such as UAVs as
Flying Base Stations (BSs) and UAVs as Aerial BSs in the presence of
eavesdroppers
(a) UAVs as Flying BSs (b) UAVs as Aerial mobile UEs
Figure 12 UAV network applications types with security services
architecture
1221 UAVs as flying BSs
The required infrastructure can be destroyed in natural disasters particularly
tsunamis earthquakes and snowstorms and the requisite emergency data traffic
cause both overloading and congestion of neighboring mm-Wave (Zeng et al
2016) A capable explanation is to rapidly introduce low-altitude UAVs as flying
9
BSs in such a network breakdown to improve the communication infrastructure to
mitigate cell congestion or site failure thus creating a small aerial cell
In this situation wireless communications can occur in an ad-hoc manner with
UAVs to UEs UAVs to UAVs As highlighted in Figure-12 (a) and control
stations of UAVs to ground It will increase capability dramatically and enlarge the
target of wireless networks in provisional measures as it is possible to create LoS
communication links among UAVs and UEs supported on the ground Yet form an
operating aerial cell system to monitor ground segments of UEs mobility which is
more stable to minimize sporadic connectivity on the other side
Also this can be expanded to allow several UAVs-BSs to be deployed to increase
the exposure area for supporting a wide range of UEs A network period various
UAVs-BSs is entirely independent A new paradigm was introduced through
collaboration between UAVs-BSs to extend the feasibility for a single UAV from
either a stand-alone active sensor to a wireless network over the next generation
There is a growing concern about the privacy problem in tandem with the brief
introduction of this network Wireless protection is the central issue of the
communication level wherever eavesdropping subsidizes for deliberately listening
to a source of secret information which harms the extensive placement of UAV-
BSs
A UAV-BSs is to mount several antennas in the UAV-BSs the benefits of multi-
antenna innovations geographical degree of freedom that offers an ability for UAV-
BSs to transmit eavesdropping airborne beams
Notice that in UAV systems multi-antenna technology can be technically applied
while directly modifying the separation of the antennas The existing system has
shown that transmitted beam forming models can significantly boost the
confidentiality efficiency of wiretap channels for multiple antenna transmitters
Noise may be inserted with the signal to substantially degrade the acknowledged
SINR at the eavesdroppers to prevent the information overflow
10
1222 UAVs as aerial UEs
This has already been demonstrated by reaping the benefits of Wi-Fi and LTE
technologies through field trials (Van der Bergh et al 2016) UAV-UEs typically
get their tasks for a variety of convincing IoT applications mainly in air freight
services like the google wing project Unlike conventional land base package
delivery but UAV delivery has distinctive merits such as
bull Acceleration of land transport as UAVs are not liable to road jams
bull Connection to areas that are difficult to reach
bull Decreasing the use of capital about workforce and electricity
UAV distribution is significantly dependent on having reliable and secure wireless
communication among UAVs and ground BSs especially if the UAV needs control
outside LoS the UAV-UEs are used which can develop LoS connectivity to cellular
BSs The UAV-UEs on the one hand provides high-speed access to data as it can
fly continuously in either direction On the other hand the installation of UAV-UEs
can lead to significant interference with the ground BSs in the execution of their
missions
A wide-scale installation of UAV-UEs is only feasible for this reason if the issues
of interference management are tackled It is widely known that interference
negatively affects wireless networks As highlighted in Figure-12 (b) indeed aerial
and ground UEs are served through a cellular network with a possible eavesdropper
that tries to intercept the message intended for permissible basic UEs
A cost-effective approach is to be used for coordination among ground BS and
UAVs to enhance secure transmission which is part of the UAVs acting as friendly
transmitters to degrade the wiretapping channels efficiency and thus enhance
secrecy efficiency A UAV acting as a mobile jammer can dramatically and
dynamically change its position as near as possible to the earth eavesdropper and
distribute them by sending the radio signals whereas strong LOS connection
characteristics are a beneficial feature with less earthly fading and shadowing
impairment
11
13 Unmanned Aerial Vehicle for 5G Networks
UAVs have technologically advanced as a revolutionary movement in delivering
pervasive connectivity from either the platforms of the sky as aerial
communication particularly for temporary User Equipment (UEs) (B Li et al
2019) Due to fully controllable UAV flexibility through miniaturization as well as
continuous cost reduction low-altitude UAVs are rapid and flexible designed for
operation and reconfiguration They are probable to have higher Line-of-Sight
(LoS) ties to ground UEs
A broad range of applications like inspection of infrastructure precision farming
and disaster area monitoring is becoming accessible in this aspect Moreover
further projects have also been set up to employ aerial platforms for broadband
access to distant elements such as the Google Loon and the Facebook Drone Project
to mention Highly populated UEs are desperate for broadband wireless
communications with the coming 5G period and network providers are supposed
to maintain numerous networks with high demands for wireless data like
multimedia streaming and also video downloads The relentless growth in the
amount of traffic of mobile networks puts a burden on operators in the form of
higher capital and operational expenditure Deploying small cell networks is an
intuitive alternative to outsource cellular traffic
Although in unforeseen or temporary events as mobile environments are
complicated volatile and heterogeneous the implementation of terrestrial
infrastructures is difficult The accessibility of aerial access points to enable
extensive complex connections is one possible solution However in unforeseen or
temporary events as mobile environments are complicated volatile and
heterogeneous the implementation of terrestrial infrastructures is difficult The
accessibility of aerial access points to enable extensive complex connections is one
possible solution UAV communication performance benefits from the simplicity
of the compact transceiver and progressive control methods that obtain broad
exposure and set up internet networks
12
Figure 13 UAV-assisted heterogeneous network architecture
The above Figure 13 is depicted to build flexibility of the network with enhanced
ability and elasticity It is a good network that offers security endowment This is
due to the transmitting information to UAV communication which is tapped
through ground unauthorized user and is known as an eavesdropper
Here through eavesdropper based on the upper layer cryptographic techniques
wireless communication in contradiction of unauthorized access has been protected
However it is very tough to achieve because of key management as well as more
computational difficulties in developing network architecture PLS affects the
characteristics of intrinsic wireless networks as a fascinating preparation such as
interference noise fading loss collecting signal characteristics in malicious
eavesdroppers and techniques of signal processing
14 Physical Layer Insecurity in UAV communication network
Jamming is either a well-defined WSN attack on a physical layer It disrupts the
radio waves being used by nodes of the network The attacker successively
expresses the denial of the simple MAC protocol over the wireless network The
impressive network can be disrupted at which a single frequency is being used
13
throughout a network (Modares et al 2011) In addition jamming can increase
energy consumption in the node by inserting impudent packets The receiver nodes
will also generate resources when receiving the packets In (Jeon 2006) four
different terms of jamming attacks that an intruder could use to interrupt the
wireless network activity Tampering is yet another physical layer assault
Table 11 Physical layer hazards and measures in UAV wireless
communication network
(Kumar et al 2014)
Hazard Security measures
Jamming Channel blacklisting and hopping
Interference Channel hopping and blacklisting
Tampering Security and key modification
Sybil Physical security of the system
Table 11 describes physical layer hazards and their security measures in WSN
which tampering and jamming are considered as the main attack in the physical
layer in WSN
141 Principles of security
The security requirement of UAV communication network is as follows (Kumar et
al 2014)
Confidentiality Ensure that only the approved sensor nodes could get the contents
of the texts
bull Authentication Ensure that the data is introduced from the sound source
bull Integrity Ensure that every received text has not been modified to be sent
by unauthorized users
14
bull Freshness Make confirm that no old information has been reiterated
bull Availability services are feasible at any time through WSN or by a single
node
The standard attacks of the physical layer are as follows (Sastry et al
2013)
bull Jamming The transmission of the radio signal can interfere only with radio
frequencies used through WSN which is known as jamming As the
capacity grows it may influence more significant portions of the network
by transmitting other radio signals The opponent will use a few nodes to
occupy the entire channel This state is called physical layer jamming which
results in a denial of service In this scenario the opponent will not be
permitted to have any knowledge but will be capable of preventing
communication to any nodes
bull Tampering Often the nodes tampered through an opponent This mode is
called tempering Here the attackers can destroy exchange and
electronically confront nodes to obtain information from counter measures
towards jamming that have been planned as spread as well as frequency
hopping
bull A security mechanism is used in WSN to track avoid and recover from
security attacks A wide range of security schemes can be devised to counter
malicious threats which can be classified as high and low levels
bull Secrecy and Authentication Most network sensor applications need
protection from eavesdropping packet alteration and injection Early
networks are used for connection layer cryptography as this approach offers
the easiest deployment of network cryptographic solutions
bull Privacy Like all other conventional networks the radio networks have also
brought secret issues to allow Initially sensor networks are implemented
for legitimate purposes and can eventually be used unexpectedly
Knowledge of active sensor nodes as well as the acquisition of data is
exceptionally crucial
15
bull Critical launch and trust setup The primary prerequisite for setting up a
network is the development of keys (cryptography) Sensor devices
typically have minimal computing capacity and public cryptographic
primitives are too difficult to adopt Critical establishment and strategies
need to be scaled to network with thousands of nodes
bull Secure routing Routing as well as data forwarding is a problem that
confronts to facilitate communication in networks Regrettably the latest
protocols encounter a variety of security flaws
bull Robustness of communication Does An opponent challenges to interrupt
the operation of the network
Figure 14 Security problems in the UAV
Figure 14 illustrated the security difficulties in a UAV The physical layer security
in the UAV wireless networks was examined The UAV had affected by both active
eavesdropper and passive eavesdropper This paper proposed the trajectory design
and cooperative UAV for constraining the eavesdropper NOMA MIMO mm-
Wave frequency band in UAV would cause better spectral efficiency and security
(Xiaofang Sun et al 2019)
UAV implementation of the 5G communication was considered advantageous The
UAV was assumed as the novel wireless network technique for the territory users
and their base stations The UAV had resulted in high altitude So the UAV had
16
considered a superior line of sight At the same time the possibility of security
problems was raised in a UAV The secrecy in the existence of eavesdropper the
jammer in the ground was performed using the UAV UAV aided territory security
was proposed The UAV was involved in inspecting the eavesdropper and hazard
jammers on the base stations territory UAV had targeted the global position system
spoofing for assisting the authentic users and performed the role of an artificial
eavesdropper for excluding the eavesdropper and jammers in the ground (H-M
Wang et al 2019)
15 Non-Orthogonal Multiple Access (NOMA) System Secured
Communication
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
151 Comparison of NOMA Vs OMA
Comparison of the NOMA and OMA can be discussed as follows
17
1511 Spectral throughput and efficiency
In OMA a resource is allotted to the distinct user whether it is good or bad in a
channel scenario like OFDMA Thus the whole process moves from less
throughput and performance
While the same frequency is allotted to the multiple-use at the same time with good
or bad channel operation in NOMA here the weak user gets the allocated for the
resources which the strong user can also use it And the interference can be reduced
by the SIC process on the receptor side of the user Consequently the probability
with the increased spectral efficiency as well the high throughput will be
maximized
1512 User fairness and higher lately
A user of fair channel complaints has higher precedence to be served in OMA In
contrast a user with a poor channel complaint is to remain activity which causes
the issue of user fairness and higher latency Yet OMA cannot assist colossal
connectivity Whereas NOMA helps multiple users with various channel
procedures and offers increased fairness massive connectivity and lower latency
1513 Compatibility
NOMA has compatibility with the current and upcoming scenario meanwhile no
need for necessary changes to the previous methods As an instance NOMA has
been bought up in the 3G Partnership Project LTE Advanced (3GPP LTE) Though
NOMA contains many characteristics that can assist the upcoming generations and
it has some restrictions that can be explored with its full benefits Those restrictions
are as follows
bull Each user has to decrypt the signals of other users until decrypted their
signal the complexity of the receiver would be strengthened in NOMA as
opposed to OMA which creates a long pause
bull Also data on channel quality for all users should be returned to the BS but
this results in substantial CSI input overhead Furthermore if any issues
arise to any consumer during the SIC process the likelihood of consecutive
decrypting errors will be improved
18
Figure 15 Comparative analysis of NOMA vrsquos OMA
As an outcome the number of users is reduced to ignore the spread of such
debugging Another aim of restricting the number of users is that there must be
substantial variations in channel revenues between users with different channel
grievances to provide network reliability
16 Problem Identification
The NOMA-based architectures main feature is to configure trusted and untrusted
users when more than one eavesdropper is present in the dense setting of todayrsquos
and future sophisticated wireless communication networks This research aims to
examine the security efficiency suggested for mission-critical applications in the
NOMA-based UAV communication network The proposed system underpins two
user NOMA frameworks The possibility of paring both users was explored with
PHY performance measures in mind Outage probability (OP) and Secrecy Outage
Probability (SOP) Dynamic Optimization Method Programming (DP) and Partially
Observable Markov Decision Process (POMDP) optimization have also been
analyzed to explore the feasibility of achieving an outage-optimal output for the
pair under the heavy users secrecy outage restriction The optimized theoretical
findings are applied to the multiuser scenario The identifications were tested
through a computer model in which POMDP has shown substantial progress over
the dynamic optimization method to program
19
17 Motivation
Unmanned aerial vehicle (UAV) wireless communications have experienced an
upsurge of interest in both military and civilian applications due to its high
mobility low cost on-demand deployment and inherent line-of-sight air-to-ground
channels However these benefits also make UAV wireless communication
systems vulnerable to malicious eavesdropping attacks
Despite the promising gains brought by UAVs the open nature of air-to-ground
wireless channels makes secure information transfer a challenging issue
specifically on the one hand information signals transmitted over wireless LoS
channels are likely to be intercepted by some undesired receivers which lead to a
risk of information leakage On the other hand wireless UAV transceivers are
vulnerable to malicious jamming attacks Hence security plays an extremely
important role in UAV wireless communications Unfortunately traditional
encryption techniques require high computational complexity leading to a large
amount of energy consumption which may not be suitable for UAV systems As an
alternative physical layer security is computationally efficient and effective in
safeguarding wireless communication networks via exploiting the inherent
randomness of wireless channels As a result various physical layer techniques
have been proposed in the literature for guaranteeing communication security
NOMA is viewed as a promising technique to provide superior spectral efficiency
by multiplexing information signals at different power levels [13] Hence it is
expected that NOMA can bring additional rate and robustness to enhance the
achievable rate in UAV physical layer security communications Consider a
scenario where a UAV acts as a relay to facilitate data delivery to two receivers
with different security clearance levels within a maximum cruising duration T The
receiver with a lower security clearance level and a higher potential with an
eavesdropper Since it has a strong motivation in intercepting signals intended for
a receiver with a higher security clearance Then when the eavesdropper suffers
from a bad channel condition NOMA is adopted to forward both confidential and
public information simultaneously Otherwise UAV only broadcasts the public
information for security issues The mode selection between NOMA and unicast is
20
chosen based on the results of the proposed resource allocation optimization In
particular for maximizing the spectral efficiency one needs to jointly optimize the
transmission scheme resource allocation and UAVrsquos trajectory However the
coupled optimization variables generally result in non-convex optimization
problems which are difficult to solve optimally As an alternative an iterative
suboptimal algorithm based on successive convex approximation can be employed
to facilitate a computationally efficient joint design We have discussed that the
NOMA scheme always outperforms OMA in all the considered scenarios which
demonstrates the spectral efficiency advantage brought by NOMA in striking a
balance between public data rate and confidential data rate
The main motive of this research is to enhance the inherently insecure PHY layer
of the NOMA-based UAV communication network NOMA-UAV communication
network requires feasible paring between trusted amp untrusted users (attacker) for
cooperative communication mainly in real-time field applications The power
allocation factor need to be optimized as per the trustworthiness of the associated
users (reliable user) and keeping the outage probability minimum for secured and
cooperative communications The pair Outage Probability and the SOP have been
optimized jointly for feasible pairing between BS amp the associated Users
18 Aim and Objective of the Research
The proposed works main objective is to examine the design of a NOMA-based
UAV communication network for enhanced Physical Layer security (PLS)
features Remarkably it is anticipated infrastructures and resources to connect
numerous devices and provide various services Researchers these days
concentrating on ways to design a heterogeneous framework like deployed small
cells air and ground-based deploy multifarious communication methods in 5G
such as millimeter-wave (mm-Wave) device-to-device (D2D) massive multiple-
input multiple-output (MIMO) Cognitive Radio (CR) and so on for improving
spectrum and energy efficiency
As a critical need especially for emergency applications the adoption of NOMA
transmission of UAV communication needs to be improved PLS A new optimal
resource allocation algorithm for some more robust and stable communication in
21
single and multiuser scenarios has been suggested here The PLS in dense
heterogeneous sensor networks has improved by the feasible pairing of trusted and
untrusted users (K Cao 2019 T Zhao 2018) In the instance of untrusted users
dynamic programming and POMDP are subjected to the channel conditions
details optimizing OP and SOP as a restricted parameter accompanied by resource
allocation (Davis 2018 L Hou 2018)
The main aim of the proposed research work areas
bull To analyze the underlying NOMA UAV communication framework with
enhanced Physical Layer security (PLS) implications for particular quest
applications
bull To examine the potential pairing of trusted and untrusted users in the
NOMA-based UAV contact network with two users and multiuser scenarios
for certain channel conditions called Channel State Information (CSI)
bull To maximize resource allocation among trusted and untrusted users by
pairing OP and Secret Outage Probability (SOP) as performance measures
with the POMDP optimization method
bull To evaluate POMDP and dynamic programming resource allocation with
two users and multiple users for both protected NOMA-based UAV
communication network scenarios
19 Thesis Organization
Chapter 1 Provides the introduction and basic concept of the proposed work with
the problem identification motivation and aim and objective of the proposed work
Here we described LTE 4G and its advanced techniques than about the NOMA and
its basic scheme UAV concepts represent their types and basic working strategy
Chapter 2 Provides a survey of the existing technologies which is related to the
proposed work The NOMA transmission schemes Merits and De-merits related
to security UAV assisted communication in heterogeneous sensor networks UAV
networks of 5G and beyond communications has been explained then about UAV-
NOMA PHY secured communication techniques as well
22
Chapter 3 Describes the proposed work of improvement of physical layer
insecurity of the NOMA The overflow and its performance measures with
simulated output have been defined in this chapter
Chapter 4 Describes Migrations proposed work from 4G LTE to advanced PHY
techniques for UAV communication The overflow and its performance measures
with simulated output have been explained in this chapter Concludes and explains
the proposed work with its outcome and the future scope of the proposed work
23
CHAPTER 2
LITERATURE REVIEW
21 Integration of UAV Networks for 5G and B5G communication
5G and B5G had been anticipated to give a unique connection among universal
users The UAV had been emerged for its advantage of wireless network and
relaying high data rate The UAV in the 5G and B5G was introduced and 5G and
B5G were updated with the new concept of Space-Air-Ground Integrated Networks
(SAGIN) Three layers were established named physical network communication
link and evaluation Besides the usage among the dense population IoT was
applied in satellite communication In which the IoT had provided the uninterrupted
service with high data rate communication The scope for flying UAVs had been
created for enhancing the number of mobile users with IoT (Ali et al 2018)
5G and B5G had projected the UAV as the vital constituent One to multiple point
transmission can be possibly advance in 5G and B5G The structural design of the
upcoming UAV (multi-tier drones) was driven by the routine of different structures
like the maximum functioning altitude communication overlap coverage and
determination The UAVs practicability (multi-tier drones) among conventional
UAVs (single-tier drones) is scrutinized in that perspective By ascertaining the
circumstances UAV (multi-tier drones) could supplement the older terrestrial
networks with RF Initially UAV (multi-tier drones) and drone-aided wireless
networks were related to finding the tasks The modified UAV (multi-tier drones)
and the drone-administered wireless networks were analyzed The enactments of
UAV (multi-tier drones) were scrutinized in the contest of spectral efficiency in the
downlink networks Their effect had exhibited the detailed network parameters The
UAV distribution (multi-tier drones) was considered advantageous for the spectral
efficiency from the downlink transmission over traditional terrestrial wireless
networks (Sekander et al 2018)
The growth of 5G and B5G wireless networks prominently hang on the
incorporation of the terrestrial and aerial systems in innovative heterogeneous
network architecture They had advanced a creative and tangible multiple UAV
24
made up of cluster UAV ndash base stations and Poisson point process with UAV and
mm-Wave frequency band Ground user equipment and UAV had exhibited as the
Poisson cluster process and then spread around the public cluster in the distinctive
cluster In particular the scrutiny was accompanied by the accumulation of extra
tiers Extra tiers were made up of multi-cluster UAV base stations and single ground
user base stations in the characteristic cluster Four-tier network systems were
designed correspondingly from the subdivision of the above-said base stations
Two-tier and four-tier association patterns were built for discovering the
involvement of the cluster networks The coverage probability for the downlink and
network throughput was derived (Ji et al 2020) The numerous subordinate title
role of the multifaceted communication systems was performed by the UAVs The
UAV was acted as the air relay in the maintenance of ground networks The UAVs
were used in the countryside hilly zones whereas the communication was
inadequate The author anticipated resolving the viable communication difficulty in
5G and B5G vehicular ad-hoc The associate communication pattern established on
the smart UAVs was planned given the crisis condition of the car ad-hoc The smart
UAVs were supporting the vehicular ad-hoc strong communication in real
situations Above and beyond its actual characteristics of the vehicular ad-hoc were
needed to be endangered to avoid the prohibited features from attaining and
exhausting for law-breaking practices Innovative UAV with a secret authentication
key arrangement was recommended in the 5G and B5G vehicular ad-hoc Because
of supporting efficiency the vehicle network which guaranteed communication
confidentiality was not negotiated The suggested pattern was confirmed to be
unaffected by numerous outbreaks by exploiting the broadly applied natural or
random ROR scheme
Furthermore the projected scheme had well calibrated the communication
overhead from the performance estimation (J Zhang et al 2020) The UANs had
obtained a phenomenal role in the research area the emergent sector of aerial
robotics The parcel transport organization monitoring occurrence shooting
surveillance and tracing were the metropolises general operations utilizing the
UAV Various domains would use 5G and B5G to improve UAV networks UAV
ecological unit was advantageous in present 5G and B5G mobile communications
For UAVs intrinsic features they were concerned for flexible movement of three-
25
dimensional space independent actions and smart locations These devices were
provided with extensive scope in cellular networks The author proposed an in-
depth assessment of implementing cooperation between UAV and 5G and B5G In
which UAV had been assimilated as a novel user equipment of aerial in present
mobile communications The UAV had implemented the duty of flying users within
the network coverage named the cellular-connected UAVs in this amalgamation
The author showed a broad examination of the incorporation tasks with 5G and
B5G novelties Continued efforts in the prototyping and validation of mobile
communication UAVs were conducted using the ground trial The paper had
focused on the current growth in 3GPP The social-economic had not been taken
into account which was considered disadvantageous (Mishra amp Natalizio 2020)
The UAV was anticipated as the significant constituent in the 5G and B5G wireless
networks 5G enables the UAV to be used in broadcasting and end-to-end
communications using the small UAV They needed a devoted and endangered
aerial spectrum in the aircraft cargo by letting small UAVs run in space in
supervisory authority The security information was obtained from the link Control
and Non-Payload Communications (CNPC) The security information contained
the regulation of UAV and the line of sight of terrestrial The CNPC application in
the 5G and satellite communication was scrutinized in this paper Payload
communication like mm-Wave networks and UAV were analyzed in this paper The
direction-finding and reconnaissance difficulties were examined UAV
communication systems were scrutinized and the hardware challenges were
discussed (Hosseini et al 2019)
The potential gain from the UAV-assisted data gathering was found in
indiscriminate IoTs The characteristic propagation was represented by utilizing the
complicated channel method (contained small- and large-scale fading) IoTs were
updated in constrain of transmit power (in high) and total energy The multi-antenna
UAV was selected in the IoTs in sequence The virtual MIMO was created by the
communication between UAV and singe antenna IoT in every transmission (W
Feng et al 2018)
The UAV was applied in the aerial coverage surveillance agricultural prediction
constructional areas and power line supervising and blood donation The flight
26
period increment payload capability fast movement and speedy placements were
implied features in the UAV so that the UAV was exploited by the applications of
5G and B5G (Ullah et al 2020)
The UAV was considered a motivation for many emergent usages and reformed
social-economic welfares The wireless networks for the UAV and the base stations
were desired for the UAV function Mobile communications were considered
suitable for finding tracing and regulating the flying UAV The wireless
communications were selected for their features of broad coverage quality of
service and secrecy The wireless communication in the UAV improved
productivity besides the line of sight (G Yang et al 2018)
22 UAV-NOMA in Physical Layer Security enhancement
The NOMA has been applied in the fifth generation (5G) technology The Multicast
Cognitive Radio (MCR) network is implemented using the NOMA and coined as
MCR- MOMA The transmission side is also included with the superimposition
code The decoding was applied at the receiving end So an unknown user is
deduced in their methodology (Meng et al 2020)
The physical layer security for the cooperative NOMA was examined Amplify
and forward decode and forward were taken into consideration for achieving
secure transmission (Chen et al 2018)
The physical layer security of the NOMA was analyzed in the broader network with
varying locality The single and multi-antenna were established in the following
cases The single antenna was taken for an end-to-end connection in a secured
manner And the multi-antenna was used for the connection of base station and
random user Finally achieved security for the multi-antenna on the transmission
side The security of the single antenna was attained by introducing the excluding
area for eliminating eavesdroppers The individual expression of security outage
probability for both single antenna and multi-antenna were derived (Yuanwei Liu
et al 2017)
The secure transmission of NOMA in large-scale applications was investigated
Stochastic Geometry was utilized for placing the eavesdropper and user nodes The
equation for secrecy outage probability was derived and expressed for evaluating
27
secure transmission Security can be improved by expanding the protected zone
(Qin et al 2016)
The power domain NOMA had the disadvantage of decoding data by other
unauthentic users of the same source For reducing unauthentic users the base
station should treat the unauthentic users with different cleaning methods The
secrecy outage probability was investigated for authentic users and unauthentic
users Both users were combined as a pair to the non-uniform distribution of original
and unauthentic users The pair outage probability of genuine users from the secrecy
outage probability restrained NOMA authentic users The derivation for pair outage
probability and the secrecy probability were expressed for calibration The
combined system had been the better security (ElHalawany amp Wu 2018)
The physical layer security was considered problematic in the wireless networks
mainly for keeping the authentic userrsquos data The UAV was acted as the base
station UAV based base station had sent the extensive data to the original users
NOMA with the multi-antenna with mm-Wave frequency band transmission had
enhanced the spectral efficiency The physical layer security was attained by
announcing the space around user locality as the eavesdroppers protected zone
Covering the entire eavesdropper area was considered a resource-consuming way
The shape optimization for the protected location in each UAV base stations
altitudes was introduced The derivations for the secrecy sum rate and the secrecy
outage probability were expressed (Rupasinghe et al 2018)
The vehicular communication system had used cooperative NOMA The secrecy
outage probability was considered in vehicular communication The relay can be
used in both modes (half-duplex and full-duplex) in vehicular communication The
closed derivation for the secrecy outage probability was expressed The security of
the full-duplex NOMA resulted better than that of the half-duplex NOMA The
limitations are that the velocity of the vehicles was not considered Figure 21 is
illustrated the conceptual model of the vehicular communication NOMA system
(Xie et al 2019)
28
Figure 21 Vehicular communication NOMA system
The physical layer security of the uplink NOMA of the large-scale devices was
examined The connection networks had investigated with the approach called
stochastic geometry The new derivation was expressed for the coverage
probability The protected zone restrains eavesdroppers to the authentic users
Efficiency secrecy throughput was examined wiretap channels and the many
original users Constant transmission and variable transmission were collectively
inspected The signal to noise and the movement to interference ratio were derived
drastically (Gomez et al 2017)
The wireless system was executed using Space-Time Block Coding (STBC)
approach in the NOMA of mm-Wave MIMO The technique focused on haphazard
users So the pairing method was introduced mainly for Random Near-Random Far
(RNRF) Here the latent period could be minimized and the RNRF has also been
deduced for the overhead issue The result revealed the systems efficiency with a
proper implementation (Ghavidel et al 2020)
The recent arbitrary beam forming method was proposed in the multiple access
NOMA The pairing had decided to the user places So the evaluation was focused
on the system overhead The result revealed that the proposed work outperformed
29
the existing methods (Aghdam et al 2020) NOMA enhances the reliability of
multi-users transmission The sum rate could be reduced for improving Quality of
Service (QoS) power transmission and signal outage probability The
eavesdropper easily accessed the multi-access systems that cause physical security
during transmission (Z Li et al 2020)
The NOMA had provided spectral efficiency speed transmission of data multiple
networking and less latent period The NOMA utilizes the power domains for
various access Cognitive Radio Networks (CRN) is used to screen illegitimate
users The legitimate users were only permitted in the CRN by the Primary User
Networks (PUN) QoS The cooperative NOMA here implemented with the PUN
and the system performance is enhanced The spectral efficiency can be improved
by the secured transmission The cooperative NOMA was additionally developed
in the CRN with the PLS A new method of cooperative NOMA in the CRN was
examined The PUN technique attains a secure transmission Multiple antennae
were used in this study for reliability and the eavesdropperndashexclusion zone method
is used for better security (B Li et al 2018)
The downlink NOMA for moderate CSI was examined The challenge of the power
domain was rectified by allocating power NOMA The power in NOMA and that
of the OMA was analyzed which resulted in a significantly reduced NOMA (Cui
et al 2016)
Here the users were multiplexed by the power domain So the method was coined
as power domain NOMA The demand arising from the B5G (Beyond 5
Generation) had reached using power domain NOMA Machine learning in the
NOMA was described (Maraqa et al 2020)
The uplink NOMA with the PLS was proposed The uplink NOMA contained a
single base station and multi-users a couple of users combined for NOMA The
known jammer emitted the pseudo-noise to divert the eavesdroppers The study had
suggested the two jammers in the uplink NOMA for secure transmission (N Zhao
et al 2020)
The Intelligent Reflecting Surface (IRS) is designed using downlink NOMA The
multi-access had used the space direction of the beams of closure users The IRS
30
had performed the multi-access for every spatial order by the cell edge users of the
orthogonal beams (Ding amp Poor 2020)
The multi-input single-output NOMA has introduced the technique called Secrecy
Beam Forming (SBF) SBF had utilized the artificial noise for NOMA security
aided users in which the eavesdropperrsquos channels deteriorated The SBFs secure
transmission can be achieved in which high successive interference cancellation is
gained (L Lv et al 2018)
The superposition coding was performed in the transmission pat The successive
interference cancellation was conducted in the receiving position These two
techniques were combined in the novel 5G aided NOMA The basic concepts of
uplink and downlink NOMA were mentioned The dominant condition was
performed in the two user clusters of NOMA The prevailing state had issued the
confirmed spectral efficiency gain in NOMA (Tabassum et al 2016)
The relay scheme in IoT was examined for the secrecy of NOMA This was coined
as relay selection NOMA The base station had transmitted the secret messages to
the two NOMA-aided sensors and eavesdroppers IoT had treated the sensors and
eavesdroppers with different power allocations The expression for certain outage
probability and the strictly positive secure capacity was derived Increasing the
number of the relay would enhance the security in the NOMA-aided IoT The
outage probability for NOMA and OMA were compared The NOMA resulted in
better outage probability in Decode and forward mode (Do et al 2019)
31
Figure 22 RS-NOMA against an external eavesdropper
The NOMA-aided IoT was utilized to fight against the external eavesdropper as
Figure 22 The secured NOMA was proposed The base station sent secret
messages to several authentic destinationsmdashseveral eavesdroppers and unauthentic
users
Nakagami-m fading model was carried out using the multiple antennae in the
channel The security was attained using the max-min transmit antenna selection
scheme Both authentic and unauthentic eavesdroppers were analyzed The closed
derivation for the cumulative distribution of the original user was expressed first
That was compared with the unauthentic user The derivation for the secrecy outage
probability was obtained to identify the level of secrecy performance (Lei et al
2018)
Reconfigurable intelligent surface (RIS) aided NOMA was established for the
secrecy performance The main disadvantage of this model was the chance of using
RIS by the eavesdropper The secret outage probability was derived in this paper
The RIS improved the secrecy of the traditional NOMA The eavesdroppers were
limited from receiving the RIS signal by enhancing the number of intelligent
elements in the RIS A high signal-to-noise ratio was obtained from this experiment
(Liang Yang amp Yuan 2020)
32
The cooperative relaying NOMA was proposed for improving private transmission
in wireless networks Full duplex mode transmitted the jamming signals That
received the required communication at first Secondly the jamming signal
emission was sent by the base station The power allocation for the jamming signal
and information signal was decided on the eavesdropper channel state information
The eavesdropper was jammed by the signal from the first phase with maximum
power Second the derivation of the secrecy outage probability was expressed by
static eavesdropper CSI (Y Cao et al 2020)
The NOMA achieved spectral efficiency and secrecy The security of the multi-
NOMA users was obtained by the successive interference cancellation (SIC)
decoding in the receiving node The conservation of the untrusted NOMA was
concentrated in this study The security can be confirmed by the properly secured
decode processing and allocating power The decoding scheme was implemented
for aiding NOMA users The decoding was performed for enhancing the sum-rate
(Thapar et al 2020) The cognitive radio network in NOMA with the external
eavesdropper was proposed (Mehr et al 2020)
The cooperative NOMA was used in the field of energy harvesting communication
The novel relaying technique was introduced for achieving secrecy The secrecy
outage probability was derived and the derivation was expressed for the three
conditions The first condition was the derivation of CSI with a passive
eavesdropper The second condition was the derivation of CSI with the unauthentic
eavesdropper The third condition was the derivation obtained from the multi-relay
nodes The increased SNR resulted in high security The increase in the number of
users deduced security This was considered a disadvantage (Salem et al 2020)
Satellite communication covered more range of broadcasting So the security
challenge was considered a big difficulty in satellite communication Downlink
NOMA was assessed with an eavesdropper for the examination of secrecy The
paper concentrated on the physical layer security of downlink satellites Here two
methods were proposed The frequency-domain NOMA was considered for gaining
spectral efficiency The multiple user interferences were obtained in the process of
overlapping Introducing a suitable technique can be performed the security for the
number of users The secrecy rate was analyzed for all authentic users (and the
33
eavesdropper) and expressed in the derivation The safety was improved using the
spectral overlap method (Yin et al 2019)
The NOMA was considered as the emerging scheme in the upcoming wireless
networks The secrecy sum rate for the downlink NOMA (with MIMO multiple
inputs multiple outputs) was examined Downlink NOMA had the base station
number of users and the eavesdropper In the limitation of transmit power and
optimal successive interference cancellation the security was expected to enhance
Downlink MIMO NOMA was considered advantageous because of its secrecy
performance and the practical usage of bandwidth The mutual information rate and
the mean square error were causing the secrecy rate optimization to the problem of
biconvex This was rectified through the alternative optimization method and the
second-order cone programming was solved (Tian et al 2017)
Table 21 Comparative analysis
The comparative analysis for the physical layer security was examined in existing
studies
SR
No
Details of Author wise Contribution to NOMA Technology
1 Author (YFeng Yang amp Yan 2017) Secrecy performance in NOMA was
conducted with the help of artificial noise in the full-duplex mode of relaying
Methodology The optimization of the power was calibrated for the source
information and the noise signal The closed derivation for the secrecy outage
probability was expressed
Usage and limitations The physical security was increased
34
2 Author (He Liu Yang amp Lau 2017) NOMA was developed in the constrain
of security
Methodology The secret message had been sent to some users and also to the
eavesdropper The Novel decoding process was conducted for excluding the
unauthentic users The iterative algorithm was used for power optimization
Usage and limitations Transmit power was reduced The quality of service
was availed
3 Author (D Wang et al 2020) The secrecy was performed in the NOMA
The security was developed against the eavesdropper outside
Methodology The channel state information was analyzed for secrecy The
quantization of CSI had performed for secrecy The derivation for the secrecy
and transmission outage probabilities were obtained
Usage and limitations The secrecy rate was enhanced
4 Author (L Lv et al 2020) The physical security of the NOMA was
improved by adding artificial noise jammer and inter-user interference The
mode of full-duplex in the updated version was used in the NOMA
Methodology The eavesdropper can be trapped the superimposed signal from
the source So the secrecy was affected
Usage and limitations The spectrum usage is effective in the NOMA
transmission scheme Numerous connections can be performed in the NOMA
NOMA is considered to be the most advantageous for the upcoming
generation communications The superimposition technique was followed
4 Author (Yue et al 2020) Secrecy performance of the NOMA was developed
with a unique framework
Methodology The eavesdroppers inside the zone and outside the coverage
zone were examined properly in this paper The outage probability for codendash
power domain NOMA was derived
Usage and limitations Safety was acquired for both internal eavesdropper
and external eavesdropper in this scheme
35
5 Author (Guezouli et al 2020) The heterogeneous sensor network of cellular
communication was taken into account
Methodology Unmanned aerial vehicles are utilized the heterogeneous
sensor network of cellular communication
Usage and limitations Extended the life span of the network system The
cost of the hardware components is drastically low The random and the
repeats in the speedy movement The latency is maximized The coverage
period is maximum
6 Author (Yao amp Xu 2019) The security in transmitting a large amount of
information in the wireless network systems are analyzed with unmanned
aerial vehicle UAV
Methodology The numbers of UAVs are arranged in the space The base
station sent the information to the UAV in the space The authentic receivers
have obtained the secured information from the UAV The HPPP
homogeneous Poisson point process is used for distributing the authentic
receiver and eavesdropper in the line of sight
Usage and limitations The increase in the number of safety zone causing the
secured transmission
7 Author (Saacutenchez et al 2020) Physical security can be achieved by the
method of a unique encryption scheme
Methodology The physical layer security of the following schemes is
discussed in this paper mm-wave NOMA massive multi-input multi-output
heterogeneous sensor networks full-duplex mode
Usage and limitations The physical layer security was analyzed for the 5G
supporting technologies Good reliability achieved The less latent obtained
Machine-type communications can be enabled
36
8 Author (Hou et al 2018) The multi-antennas were used in NOMA with
UAV The stochastic geometric approach was examined
Methodology The multi-input multi-output kind of NOMA was utilized In
common the stochastic geometric approach was used for drastically moving
NOMA
Usage and limitations The maximum signal-to-noise ratio was obtained in
this scheme Power optimization was achieved The path loss is less Good
spectral efficiency was obtained
9 Author (Miao et al 2020) The broadcast type of communication was
performed The less weighed three-dimensional space for 5G communication
was analyzed
Methodology Both the performances of multicast and broadcast were
enabled UAV-assisted 5G communication systems are emerging in the
upcoming wireless networks
Usage and limitations Better flexibility in the network Continuous mobility
One lined line of sight
10 Author (Majhi amp Mitra 2020) The secure communication in cognitive radio
by NOMA was propounded
Methodology The antenna strategy of giving minimum outage probability
was concluded from this study
Usage and limitations The limitation is that more spectral efficiency causes
security issues
11 Author (X Zhao amp Sun 2020) Secure communication of the physical layer
in Visible light NOMA Communication was proposed
Methodology Energy optimization in security constrain was propounded for
achieving overall performance
Usage and limitations It is difficult to find optimal results because energy
optimization is the nonconvex issue
37
12 Author (Tuan amp Hong 2020) Secure communication in simultaneous
wireless information and power transfer NOMA was remitted
Methodology Eavesdropper is used for security purposes between the user
and base station using energy relays Known jammer is used for secure
transmission For energy efficiency storing and transferring were propounded
Usage and limitations Jamming requires extra power allocation
13 Author (Vaezi et al 2019) NOMA for 5G in mmWave MIMO cooperative
and cognitive were analyzed in this study
Methodology SWIFT NOMA is useful for weak receivers
MIMO using more antenna
Usage and limitations multi-antenna utilization cause high power
consumption
14 Author (Vaezi et al 2019) Mobile edge computing NOMA was proposed to
optimize power
Methodology Minimum latency and less power consumption
Usage and limitations Transfer power allocation must be calibrated
15 Author (Faraji-Biregani amp Fotohi 2020) Security in UAV communication
was proposed by introducing mobile agents
Methodology Malicious user of UAV was identified
Usage and limitations Three-phase power is essential
16 Author (G Zhang et al 2019) Secure communication in 5G UAV was
propounded by joint trajectory carrying out in physical layer
Methodology Power optimization was proposed for security
Usage and limitations Security in the physical layer was achieved by
optimization of trajectory
17 Author (Fotohi et al 2020) Agent-based self-protection was propounded in
UAN for secure communication
Methodology This method imitates the immune system of human beings
Less cost
Usage and limitations Energy is not optimized properly This approach
needs to consider other malicious attackers
38
18 Author (Shang Liu Ma amp Fan 2019) Vehicle to everything approach was
propounded for security in a UAV
Methodology Security of vehicle to the vehicle was proposed by considering
eavesdroppers active and passive attacks
Usage and limitations High price
19 Author (Kantor et al 2017) The flight path was calibrated in a UAV
Methodology Security performance was achieved by encryption as well as
anonymization
Usage and limitations High in cost and hardware structure occupies more
place
23 Research Methodology
The NOMA-based cellular architecture for UAV communication has been
considered here as reference network architecture Rayleigh fading has been
assumed as a channel characteristic The performance parameters for PHY layer
security are (1) Pair Outage probability (Pair OP) between two users trusted near
user designated as U1 and untrusted far user designated as U2) and (02) Secrecy
Outage Probability (SOP) of trusted near user designated as U1 The aim is to
achieve optimal Pair OP for the given constrained SOP of User U1 so that network
resources can be efficiently allocated to both users without compromising the
secrecy of trusted User U1
The mathematical analysis from reference literature (ElHalawany et al 2018) has
verified and supported the joint optimization of the Pair OP and SOP for the given
power allocation factor in NOMA This research work is extended as providing
more efficient resource allocation using the POMDP algorithm in a given scenario
First the varying distance of untrusted user U2 from BS as a critical selection
parameter that affects Pair OP amp SOP of user U1 and U2 both has been simulated
and the feasible and infeasible pairing of both users have been analyzed The
optimal power allocation factor for feasible pairing as the constrained problem is
optimized by opting for POMDP as a resource allocation algorithm wherein the
SOP of user U1 is strictly maintained for given CSI POMDP provides optimum
39
power allocation factor for trusted and untrusted users pairing as shown in the
proposed flow of POMDP algorithm is used to model a variety of real-world
sequential decision-making problems After the BS has been set up the distance
between the BS and the user is calculated and if space is less than 200m it is
defined as a trusted user While if the range is more than 200m it is described as
untrusted users In the case of trusted users the channel state information (CSI) is
provided to the proposed algorithm POMDP for reliable and efficient resource
allocation
24 Summary
UAVs play a central role in providing network service recovery in a disaster-
stricken region enhancing public safety networks or handling other emergencies
when Ultra-Reliable Low-Latency Communication is required In particular UAV-
assisted communication can be regarded as an important complement to the 5G
cellular networks Surveyed literature related to UAV communications published
over the past several years emphasized the cybersecurity and channel modeling for
UAV communications etc Security is one of the critical issues in communications
Modern communication networks are based on the layered architecture from the
physical layer up to the application layer A great deal of effort has been made to
develop the cryptographic protocols above the physical layer However the
physical layer is not as robust as that in wired communications The physical layer
in wireless communication is more complex than the counterpart in other
communication paradigms The concerns come from not only the noises but also
many types of fading Recently there has been an influential interest in studying
the security issues in the physical layer Security is highlighted as another
challenge and the implementation of physical layer security techniques is seen as
a difficult task PHY security in NOMA systems under the presence of external
eavesdroppers or untrusted relay nodes Upcoming 5G networks for unpredicted or
crisis (disaster management) the placement of terrestrial substructures is
economically infeasible and challenging due to high operational expenditure as well
as sophisticated and volatile environments
To address such novel issues intelligent heterogeneous architecture by leverage
UAV has been well-thought-out to be a promising novel model For advancing the
40
performance of the UAV 5G communication system physical layer techniques are
of many effects as they have impacted the applications of UAVs Security of
NOMA-based UAV communication network has been scrutinized for optimization
as physical layer security
41
CHAPTER-3
SYSTEM MODEL FOR NOMA-UAV
COMMUNICATION
31 NOMA-UAV System Secured Communication for 5G
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
311 The basic scheme of NOMA
The NOMA system allowed several users to be served simultaneously by the
transmitter To transfer a linear combination of different signals towards the
recipient the system of proportional representation superposition coding (SC) The
transformed signal is provided through
σ ඥ119875119896 119878119896119870119896 =1 -------------------------------------- (1)
Where 119927119948 represents the transmit power assigned toward user k th
119930119948 indicates the normalized message used for user k th
42
The instantaneous total converses power is σ 119927119948119922119948=1 The received signal at user kth
and the eavesdropper are offered through
119910119896 = ℎ119896 σ ඥ119875119896 119878119896119870119896=1 + 119899119896 -------------------------- (2)
119910119890 = ℎ119890 σ ඥ119875119896 119878119896119870119896=1 + 119899119890 -------------------------- (3)
Where 119951119948 and 119951119942 indicated the zero-mean Additive White Gaussian Noise
(AWGN) at user k th with variance 1205901198962 and the zero mean AWGN at eavesdropper
with variance 1206481199422 respectively We assume that the noise variances at all the users
are identical
ie 12059012 = ⋯ = 120590119896
2 = 1205901198902
As per NOMAs process the SIC is followed by all users to decrypt the message to
the same decoding order Notice that it is not known what the optimal decoding
order is for the NOMA method that corresponds to secrecy
Therefore the mth message to be encoded to the user might not be the mth message
to the user As such we also have to add the π variable For example if 120587(1) =
3 then the first message to be decoded for the SIC is the message for the user 120645(119947)
forall j lt k before decoding its letter to remove the inter-user interference successively
Then the user 120645(119948) denotes its message while treating the news for all the user
120645(119946)foralli gt k as the interferences The received Signal-to-interference-plus ndashnoise
ratio (SINRs) at user 120587(119896) k lt K and user 120587(119870) to decode their messages are
respectively given by
119878119868119873119877120587119896=
120574120587(119896)119875120587(119896)
1+120574120587(119896) σ 119875120587(119894)119896119894=119896+1
119896 lt 119870 --------------------(4)
119878119868119873119877120587119870= 120574120587(119870)119875120587(119870) --------------------------------------(5)
Were 120574120587(119896) =หℎ120587(119896)ห
2
1205901199062
൘
43
Also the acknowledged SINR at user 120587(119898) to decrypt the message 120633120645(119948) 119896 lt
119898 le 119870 is given by
119878119868119873119877120587119896=
120574120587(119898)119875120587(119896)
1+120574120587(119898) σ 119875120587(119894)119896119894=119896+1
kltmle 119870 --------------(6)
Similarly the acknowledged SINRs by the eavesdropper of the message 120575119896 119896 lt
119870 and the message 120575119896 are respectively given by
119878119868119873119877120587macr
119896=
120574119890119875120587(119896)
1+120574119890 σ 119875120587(119894)119896119894=119896+1
klt119870 ----------------- ------(7)
119878119868119873119877120587macr
119896=
ȁℎ119890ȁ2119875120587(119896)
1205901198902 = 120574119890119875120587(119896) klt119870 ---------------------(8)
Where 120574119890=ȁℎ119890ȁ2
1205901198902൘
Notice that here expressions for the obtained SINRs at eavesdropper overestimate
the skill of eavesdropper Here a worst-case inference from the viewpoint of
legitimate users is made That is the messages have already been decrypted by the
eavesdropper for all users π (j) forall j lt k before attempting to decrypt the message
for the user π (k)
The presumption also assumes that the decrypting order and power distribution are
understood by the eavesdropper The eavesdropper may or may not recognize the
decoding order of the users and the allocation of power may or may not recognize
the messages for all users π (j) forall j lt k before attempting to decode messages for
users π (k) However since the eavesdropper has been unable to alert the authorized
customers of its capacity and the current CSI the approved user would be unable
to know the eavesdroppers details Therefore we have to pursue the worst-case
scenario for the permissible users point of view due to the liberality required by the
safety reports It highlights that the worst-case assumption in the study and design
of transmission schemes with secrecy requirements has been generally adopted
The proposed study has been evaluated using performance measures Here we
analyze NOMA with downlink and uplink networks suggested by SINR and Sum
44
Rate survey High SNR is then simulated to contrast the OMA and NOMA
processes
312 Downlink of NOMA
The Downlink of the NOMA network on the transmitter side is described in Figure
31 SIC method is supposed to be carried out successively on the receiver side of
each user until another signal is restored The coefficients of users are owed in an
inversely proportional manner based on their available bandwidth
Figure 31 Downlink NOMA network
A consumer with a poor available bandwidth has a transmission capacity of a
higher range than a consumer with strong available bandwidth As a consequence
the consumer with the higher power assumes the signals of other users to be noisy
and automatically restores the signal without conducting any SIC operation The
receiver of each consumer detects indications that are stronger than those of the
desired signal These impulses are then deducted from the power and this process
continues until the signal has been calculated Both users decrypt their signaling by
considering other users with lower correlations The signal is calculated as
45
119904 = σ 119886119894119875119904119883119894119871119894=1 -----------------------------------------------(1)
Where Xi is the user ithrsquos information through unit energy
Ps is the capacity of transmission at the BS
ti is the coefficient of power assigned for user i
Although without the need for lack of generality the channel profits are expected
to be graded as ȁℎ1ȁ2 le ȁℎ2ȁ2 le ⋯ ȁℎ119871ȁ2
Where 119945119923 is the coefficient of the channel of the user Lth
The received signal of the Lth user is calculated as
1199101 = ℎ119897119904 + 119899119897 = ℎ119897 σ ξ119886119894119875119904119883119894119871119894=1 + 119899119897 -----------------------------(2)
Where n1 is zero mean Complex Gaussian noise with a variance of 1206482SINR
analysis with the equation (2) the SNR of Lth user to identify the user 119895 le 1with
119895 ne 1
119878119868119873119877119871 = 1198861120574 ȁℎ1ȁ2120574ȁℎ1ȁ2൘ σ 119886119894 + 1119871
119894=119871+1 ------------------------(3)
Where 120632 = 1198751199041205902ൗ represents the SNR
Sum rate analysis After identifying the SINR of the downlink the sum rate will
also be done quickly
The NOMAs downlink data rate of Lth user can be calculated as
1198771119873119874119872119860minus119889 = 1198971199001198922(1 + 119878119868119873119877119871) --------------------(4)
313 Uplink of NOMA
The Uplink NOMA is depicted in Figure 32 where each user sends a signal to the
BS SIC iterations are supported to classify the signals of mobile users If both
channels are identical and BS sends the coefficients of power allocation to mobile
users the received signal can be interpreted as a synchronous uplink to the NOMA
46
119955 = σ ℎ119894ඥ119886119894119875119909119894119871119894=1 +n ----------------------------------(5)
Where hi is the coefficient of the channel for the ith user
119927119961119946 is the extreme transmission capacity supposed to be general to all users
N is zero-mean Gaussian noise with a variance of 1206482
Figure 32 Uplink NOMA
Analysis of SINR The BS decrypts the signals of the users as per the coefficients
of the users and the SINR for the Lth user can be defined as
119878119868119873119877119871 = 119886119897120574ȁℎ119897ȁ2120574 σ 119886119894ȁℎ119894ȁ2 + 1119897minus1
119894=1൘ ----------------------------(6)
Where 120574 = 1198751205902ൗ indicates SNR
Analysis of Sum rate The sum rate of uplink NOMA when 120632 minus infin can be
computed as
119877119904119906119898119873119874119872119860minus119906 asymp 1198971199001198922(120574 σ ȁℎ119897ȁ119871
119894=1 2 ------------------------ (7)
47
314 Comparison of NOMA and OMA
The attainable data rate of the Lth user of OMA intended for both uplink as well as
the downlink is estimated as
119877119904119906119898119874119872119860 = σ 120572 1198971199001198922120574(1 +
120573119897ȁℎ119897ȁ2
120572119897119871119894=1 ) --------------------------(8)
Just for convenience two users should evaluate the summation of uplink rates for
NOMA and OMA The use of both the uplink rate of NOMA and OMA at high
SNR can be calculated as---
119877119904119906119898119873119874119872119860 asymp 1198971199001198922(120574 ȁℎ1ȁ2 + 120574ȁℎ2ȁ2 ------------------------- (9)
equation (7) and (8) it is seen that 119877119904119906119898119874119872119860 le 119877119904119906119898
119873119874119872119860
Here we note 119929119956119958119950119926119924119912 le 119929119956119958119950
119925119926119924119912 shows that NOMA performed better than OMA in
terms of sum rate in both downlinks as well as uplink of two user networks
The sum rate will be calculated after the SNR as the formulation is shown In this
proposed work multiple users are propagated to the process of NOMA and here a
comparison of NOMA as well OMA has been defined The NOMA uplink and
downlink using the OFDMA method for the
32 PLS performance metrics in NOMA -UAV communication
This chapter mainly describes the proposed work to examine the availability of the
outage probability of the pair below an authorized user According to the decryption
of SIC availability and spectrum sharing the unauthorized user can function as an
eavesdropper and obtain an outage probability (OP) for all situations with the
Secrecy Outage Probability (SOP)
321 SOP and OP - two user and multi-user NOMA system
NOMA system has the capability for assigning multiple data over the transmission
signal through high-level coding (Shim amp An 2018) Thus it contains spectrum
efficiency when opposed to OMA But this has a limitation in security As an
48
instance if the eavesdropper is reached then it obtains multiple user data in the
interference of the NOMA signal Thus the security issues are more significant in
this system Here PLS is an available method to rectify the attack intended for
malicious users (Dai et al 2015)
Additionally data should be transmitted confidentially if the root and eavesdropper
networks can be evaluated and the recipient can decrypt the received text At the
same time the eavesdropper is not able to solve the text that has been interrupted
PLS is at the cutting edge of wireless communication security technology to prevent
eavesdropping attacks The SOP is described as the likelihood that the near users
attainable device confidentiality capability will fall under the predefined target
confidentiality rate as set out in (Shim et al 2017)
Through SOP we can calculate the level of protection of the device As an example
the low-secret OP system makes the system more stable in terms of security than
the high SOP system To boost the efficiency of the PLS CSI-based opportunistic
scheduling links to a scheduled destination in a particular time slot It has been
documented as an enticing scheduling scheme (Long Yang et al 2016) because the
various wireless channel has been exploited Opportunistic scheduling is also
considered to be one of the strategies used to increase the confidentiality efficiency
of the NOMA method
322 System Model
Suppose a multi-user NOMA system of downlink containing BS a selection of K
nearer users as N= 119873119894ȁ12 119870 and a range of M far users as F=
119865119895ȁ12 119872 and an eavesdropper E as displayed in Figure 33 More
specifically nearer users should make active use of the SIC methodology to
distinguish far user F Both the legitimate and illegitimate receivers are furnished
through a single antenna and operate in a half-duplex manner
49
Figure 33 Multi-two user architecture of NOMA system (Shim amp An 2018)
Here 119945119935119936 and ȁ119945119935119936ȁ2
Where X120598ሼ119878ሽ 119884120598119873 cup ሼ119864ሽ represent the channel coefficient and the corresponding
channel gain of the X-Y value
Taking into consideration that each wireless channel for Rayleigh block fading 119945119935119936
can be incorporated as an independently distributed random Gaussian variable with
zero mean and affirmative ℷ119935119936 Variance The outcome of channel gain ȁ119945119935119936ȁ2is an
exponential variable randomly through the Probability Density Function (PDF)
119891ȁℎ119883119884ȁ2(119911) = ቀ1
ℷ119883119884ൗ ቁ 119890119909119901 (minus 119911
ℷ119883119884ൗ )
if zge 0 119900119905ℎ119890119903119908119894119904119890119891ȁℎ119883119884ȁ2(119911) = 0 -----------------(1)
Especially the average channel profit can be represented as
ℷ119883119884= ൬119889119883119884
1198890൘ ൰
minus휀
ℒ ------------------(2)
When 120027 is the attenuation of the received signal 119941119935119936 signifies the distance among
X and Y 1199410 indicates the space and 120656 is the exponent of the path loss It is believed
that the source is entirely familiar with the CSI of both legitimate users and
eavesdroppers
50
323 Partially Observable Markov Decision Process-POMDP
Figure 34 Flow Diagram of the proposed system
The proposed overflow is shown in Figure 34 After the BS has been set up the
distance between the BS and the user is calculated and if space is less than 200m
it is defined as a trusted user While if the range is more than 200m it is described
as untrusted users In the event of untrusted users the channel state information is
accessible to the POMDP accompanied by the allocation of resources The study
was carried out after the machine operation Here a NOMA-oriented cellular setup
provided with a BS at the Centre and two users was described in Figure 35
51
Figure 35 Near and Far User
The adjacent user has a high level of security confirmation needed to protect the
layer since the low-security clearance user is situated at a distance away from the
BS P is specified as the highest level of transmitting power In this chapter it is
presumed that all DNS servers are furnished utilizing an individual antenna and all
channels are supposed to be individually static identical to the Rayleigh
dissemination concerning distribution
119862119873(0 120575119898
minus120572
212059601 2Τ
)
In which 120633119950 is the range between the BS and the nodes 119932119950 Here the path-loss
exponent and constant are defined as 120630 and 1206540 Furthermore BS is assumed to
have predicted the position of the user so that a better CSI can be obtained at BS
that is elaborate in user pairing
The BS transmits the superimposed mixture
119909119905 = ඥ1199051199041 + ඥ1 minus 1199051199042 ------------------------------- (3)
In which 1199561 and 1199562 are the unit of power signals received by users 1199321 and 1199322
respectively t is the power allocation coefficient for the adjacent user
1199031 = ℎ1119909119905ξ119875 + 1198991 ------------------------------- (4)
1199032 = ℎ2119909119905ξ119875 + 1198992 ----------------------------------(5)
Where 1199451119886119899119889 1199452 the channel profit link with the fading of small scale since the
BS to the user 1199321 and 1199322 respectively The additional Gaussian noise with variance
52
is denoted 1199511 119886119899119889 1199512 and zero mean 119894119904 119889119890119899119900119905119890119889119886119904 (1199250) and it is assumed
that the BS conveyed SNR is 120646 = 1199271199250
ൗ
In the NOMA technique additional users with more power may decode their signal
by recognizing the adjacent signal as noise without decoding the adjacent user
message In the previous equation 1198801 is supposed to first solve a weak signal by
decoding its own SIC signal1198802 which is an unauthenticated user attempted to
decrypt the nearer user text after decrypting the adjacent usage text after decoding
its own SIC message The following equation has therefore been achieved
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2 ----------------(6)
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2 ----------------(7)
119879119900119905119886119897119904119894119899119903 = 11987811986811987311987721 1198781198681198731198771
1 119878119868119873119877221198781198681198731198771
2 -----------------(8)
Where 119930119920119925119929119950119951
indicates the SINR ratio of user mth that was decoded by 119932119951 for
119898 119899 isin ሼ119894 2ሽ and the channels gain followed an exponential distribution with the
parameter 120649119950=120654120782120633119950minus120630
324 Problem formulation
As a result the BS could achieve and provide better communication for users who
are vulnerable to security threats from unauthenticated users the proposed
framework identified two kinds of QoS energy efficiency that could be considered
essential for addressing the problem In a particular study a pair of OPs was
specified to check the reliability at which the attainable data rate for users is equal
to or greater than the threshold of minimum reach The following issue aimed at
reducing the pair OP to an SOP factor intended for the user 119932120783 that is provided by
Where 1199270is Outage Probability- (OP)
1199271 is Secrecy Outage probability user U1 119930119926119927(119932120783) and
120631 the permissible SOP threshold
53
33 Performance Analysis Improving PLS Insecurity of NOMA
System
331 The Pair OP Calculation
Through Shannons capacity formula and assuming 119914120783119957119945 119886119899119889 119914120784
119957119945 as the
threshold capacities of users 119932120783 119886119899119889 119932120784 respectively the combination of OP
could be offered by
119927119954 = 120783 minus 119928120783119961119928120784 in which 120649119950 = 120784119940119950119957119945
119950 isin ሼ119946 120784ሽ -------------(9)
empty120783 =120649120784
120646(120783+119957+120649120784119957) empty120784 =120649120783
120646119957
119928120783 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ 120782 lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 ------------------------(10)
Case 1empty1 gt empty2 for having the limitation of the allocation of power factor (t)
required to be satisfied (tgt120649120783
120649120783+120649120784+120649120783120649120784) and for this case 119928120784 could be attained as
follows
119928120784 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ
120649120783
120649120783+120649120784+120649120783120649120784lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 --------------(11)
Case 2 empty1 lt empty2 Like case 1 it was stated that the opposite constraint depends
on
t gt 1206491
1206491+1206492+12064911206492 and 1199282 can be evaluated as follows
119928120784 = ൝119942119961119953 ቀ
minusempty120784
120649120783ቁ 120782 lt
120649120783
120649120783+120649120784+120649120783120649120784
120782 119952119957119945119942119955119960119946119956119942 ---------------------(12)
54
Table 31 List of parameters
Parameters Description
N Number of nearer users
M Number of far users
E Eavesdropper
ℎ119909119910 Channel coefficient between 119909119905ℎchannel and 119910119905ℎ users
119889119883119884 The distance among x and y
1198890 Space
120598 An exponent of the path loss
ℒ Attenuation of the received signal
120575119898 the range between the BS and the nodes
1205960 Path loss constant
120572 Path loss exponent
1199041 1199042 Unit of power signals received by users 1198801 and 1198802
T Power allocation factor for the adjacent user
ℎ1119886119899119889ℎ2 Channel coefficient of 1198801 and 1198802with the fading of small
scale
11989911198861198991198891198992 Gaussian noise variance
1198730 Zero mean for Gaussian noise
120588 Signal to noise ratio
119878119868119873119877119898119899
Signal to interference noise ratio of users n and m channels
55
120591119898 Exponential distribution parameters
1198750 Pair of OP
1198781198741198751 119878119874119875(1198801)
120573 The permissible SOP threshold
Table 31 depicts the list of parameters used in the proposed methodology which
are useful for assigning and the values are assigned based on the parameters given
for the experimental evaluation as well This chapter concludes with the basic and
the actual flow of the proposed method to know more about the work in the
simulation process
332 Pseudo-code for the proposed algorithm
Algorithm I
Step 1 Estimate Rayleigh distribution
119862119873(0 120575119898minus120572 2Τ
1205961199001 2Τ
) where
120633119950 is the distance between nodes 119932119950 and the BS
120630 is the path-loss exponent and
120654119952 is the path-loss constant
Step 2 The BS broadcasts the superimposed mixture and input signal as follows
119909119905 = ξ1199051199041 + ξ1 minus 1199051199042
Where 119956120783 and 119956120784 are the unit power signals received by users 119932120783 and 119932120784
respectively 119957 is the Power allocation coefficient for the near user
Step 3 The received signal is as follows
1199031 = ℎ1119909119905ξ119875 + 1198991
1199032 = ℎ2119909119905ξ119875 + 1198992 where
56
119945120783 and 119945120784 are the channel gain associated with the
small-scale fading from the BS to users 119932120783 and 119932120784 respectively
1199511 and 1199512 are the additive white Gaussian noise with zero mean and variance
119925120782
Step 4 the BS transmit signal-to-noise ratio (SNR)
120646 = 119927119925120782
Step 5 Signal-to-Interference-plus-Noise-Ratio (SINR) for the two users 119932120783
decodes the signal of the weak user first then decodes its own signal after using
SIC 119932120784 is an untrusted user and tries to decode the near user message after
decoding its own message using SIC
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588ൗ and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ2ȁ2+1120588ൗ and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2
119879119900119905119886119897119904119894119899119903 = ሼ11987811986811987311987721 1198781198681198731198771
1 11987811986811987311987722 1198781198681198731198771
2ሽ
where 119930119920119925119929119950119951
is the signal-to-interference-plus-noise-ratio (SINR)
of user 119950th decoded by 119932119951 for 119898 119899120598ሼ119894 2ሽ and ȁ119945119950ȁ2 is the
channels gain of 119932119950
Algorithm II
Partially observable Markov decision process
Step 1 Prediction of the maximum capacity of channel with respect to the data rate
119955119943 = 119877(119878119909119863)
S is denoted as states
Let D be the channel characteristics which are considering here as actions
Reward function R
Step 2 The agent receives an observation 119900120598120118which depends on the new state of
the environment 119930prime and on the just taken action 119941 with probability
119926(119952ȁ119956prime 119941)
Step 3 Reward earned at time t is expressed as
57
119903119891119905 = 119877(119878119909119863)119905
Step 4 reward function on belief states
119919 is the belief states over POMDP states
119919119943 is the belief state transition function
119955119943 = 119877(119867119909119863)
Step 5 The reward function is updated based on the belief MDP the agent only
cares about which action will yield the largest expected immediate reward ie the
maximum capacity channel
119861119891 ቀℎ 119889 ℎprimeቁ = 119875119903 (
119900120598120118
ℎprimeȁℎ 119889 119900) 119875119903(119900ȁ119889 ℎ) 119861119891
119875119903(ℎprimeȁℎ 119889 119900) = ቄ1119894119891119905ℎ119890119887119890119897119894119890119891119906119901119889119886119905119890119908119894119905ℎ119886119903119892119906119898119890119899119905119904ℎ 119889 119900119903119890119905119906119903119899119904ℎprime
0119900119905ℎ119890119903119908119894119904119890
119903119891(ℎ 119889) = σ ℎ(119904)119877(119904 119889)119904isin119878
34 SUMMARY
The NOMA-UAV communication framework has been proposed in this research
work and the Physical Layer security aspect has been focused on for optimization
The PLS performance metrics selected are SOP amp Pair OP in the proposed system
model The POMDP framework is general enough to model a variety of real-world
sequential decision-making problems Applications include robot navigation
problems machine maintenance and planning under uncertainty in general Here
we have adopted the User pairing POMDP algorithm for resource allocation in two
users amp multi-user NOMA-UAV communication networks The proposed study has
been evaluated using performance measures by varying distances of trusted amp
untrusted users from the base station as well as for varying SINR conditions The
simulation results and outcomes are discussed in a further chapter
58
CHAPTER 4
RESULT AND DISCUSSION
41 PERFORMANCE MEASURES OF SECURED NOMA-
UAV COMMUNICATION MODEL
Drones or UAV-based communication technology has been thoroughly studied and
adopted by the 3GPP standard UAV systems have been envisaged to form an
integral part of future wireless communication applications due to their dynamic
flexible and flying nature Due to their ability to reach higher altitudes they usually
have dominant LOS channels with the ground nodes This capability can be used to
provide confidentiality to the legitimate receivers against the eavesdroppers This
can be done by deploying UAVs to launch more effective jamming signal attacks
to terrestrial eavesdroppers The conventional cooperative jamming schemes make
an assumption that the locations of terrestrial jammers are fixed which might
compromise the secrecy of the system if the jammers are located far away from the
eavesdroppers and is also not practical as it makes an assumption of perfect CSI of
the jammer to eavesdropper channel
Here in the proposed scenario of the NOMA-UAV communication network two
key PHY layer security metrics SOP amp Pair Outage Probability have been jointly
optimized for a more effective power allocation factor for NOMA cellular
architecture The varying channel characteristics have been analyzed to achieve the
desired SOP with the constrained threshold minimum target secrecy rate for the
two-user scenario POMDP Algorithm iteratively provides the optimized SINR that
has been used to keep trusted users in pair with the untrusted user with minimum
achievable outage probability
The proposed NOMA-UAV System model has been simulated in MATLAB 2019b
version with mainly Communications System Toolbox Optimization Toolbox RF
Toolbox Signal Processing Toolbox Statistics and Machine Learning Toolbox
The simulation has been carried out for two-user pair to achieve desired secrecy
target rate and feasible pairing between trusted user amp untrusted user(eves-dropper)
59
The optimal-outage performance of minimized pair OP subjected to SOP constraint
has been solved by both dynamic programming optimization and POMDP
optimization approaches
The simulation of the proposed framework for the UAV-NOMA communication
network has been carried out and discussed in two parts two user models and a
multi-user model as below mentioned discussion The base station is deployed at
the center of a cell of radius 1000 m There are two users in the system under
consideration The channel between two nodes in the system suffers both the small-
scale fading and path loss effect Small-scale fading follows the exponential
distribution with the mean value 1 The noise signal of all channels has a Gaussian
distribution with 0 mean and variance 1 The path loss exponent α and the path loss
constant PLo are set to 2 and 01 respectively We assume a normalized bandwidth
of 1 Hz The SOP constraint threshold is assumed 01 and the target secrecy rate is
001 The power allocation coefficient is 015 and the BS transmitted SINR is
assumed 15dB for the proposed model As per the NOMA transmission scheme
SINR has been obtained for User 1 amp User 2 both for SIC decoding POMDP
algorithm optimally tunes the SINR value for User 1 amp User 2 that is considered to
select optimal power allocation coefficient for both trusted and untrusted users with
respective SOP of User1
42 Numerical results and Discussion
Table 41 Simulation Parameters
Parameters Values
Untrusted user Distance (d2) 200-1000 (300 700)
BS transmit signal-to-noise ratio (SNR) (120588) in dB 15
Sop constraint constant threshold (β) 01
Power allocation factor (t) 015
Trusted User distance (d1) 2-
60
Cell Radius (rd) 1000 meters
Path loss exponent (α) 2
Path loss constant (PLo) 01
Normalized bandwidth in Hz 1
Target secrecy rate (Rs) 001
No of Bits 100
Pair Outage Probability (P0) 05250
SINR 5319 15305 5162
10247
421 Feasible amp Infeasible pairing of trusted amp Untrusted users
In this section the CSI value broadcasted by Base Station is assumed 15 dB initially
and for varying channel conditions various SINR values of 120646 = minus20 minus10 20 dB
is described with target secrecy rate 0005 and 001 for power allocation coefficient
015 and User 1 distance at 200m is shown in the Figure 41 below
Figure 41 Impact on Sop with increase distance between BS and user U2
61
Varying target secrecy rate threshold from 0005 to 001 the obtained result in
Figure 42 revealed that the 1199321 is a gradually reducing function for the distance of
untrusted user d2 that implies that the increasing value of d2 leads to the
improvement of the SOP of 1198801
Figure42 Impact on Sop with increase distance between BS and user U2
Since the offered constant threshold 120656 in SOP limit1199322 which should be located at
a larger space when compared with a value of threshold to attain the SOP of 1199321
apart from that it is expected the high target secrecy rate maximizes the SOP of 1199321
Here in below figure the power allocation coefficient has been varied from 0 to 1
with threshold value of t and the desired t_sop for feasible pairing
Figure 43 Feasible pairing t Vs pair OP
62
Pair OP in case of rising 1199322 untrusted user in d2 for different BS transfer the SNR
where t= 015 and d1=200mThe infeasible pairing of SOP (1199321) and the OP pair
by the enhanced allocation of the power (t) d1 (200m) d2 (300m) 120646 = 15 dB and
120656 = 0
Figure 44 shows the identical plotting of data by adjusting the unauthenticated
level of the user through converting it to a BS closer distance (d2=300m) Accuracy
is compared and checked with the full spectrum of numerical simulations The
result has shown that the effectiveness is based on a comparative study of the two
consumers of the BS
Figure 44 Infeasible pairing t Vs pair OP
422 The Secrecy Outage Probability amp Pair Outage Probability
Feasible paring in the SOP of pair OP and 1199321 with the improved power allocation
factor t in which d2=700m d1=200m 120646 = 15119889119861 and The result described that
the OP and SOP of the user 1199321 with increased for two various distances of the 1199322
untrusted user The simulation result approves the convex nature 120656 = 0 1of the OP
and the SOP is sequentially decreased depending on t Generally when it enhances
the power owed to the weak user text reduces that develop the ability of 1198802 for
discerning the superior positioned signals therefore enhancing the SOP of 1198801
63
Figure 45 Secrecy outage probability
Figure 46 Pair outage probability
423 SNR versus Strictly Positive Secrecy Rate
Figure 47 proved that the potential for confidentiality is superior to the existing
techniques The proposed application for pre-coding improves the efficiency of the
device The transmission power of the system is the power needed for the
transmission of particular data
64
Figure 47 SNR versus Strictly positive secrecy rate
If there is a growth in the number of users there is a risk of inference in the
transmission of data and thus the reliability of the data rate may be affected Based
on these cases the efficiency of the antenna power to be withheld and occupy the
data determined
424 Power radiated by per MMBs antenna
In the case of multi-users scenario when there are more than two users then the
allocation of an optimized resource block to all users is the key parameter to achieve
desired outage efficiency because strong users require higher SNR for higher data
rates and weak users are allocated minimum threshold SNR for lower data rate
requirements to maintain suitable pairing OP and SOP balance
Figure 48 Power radiated by per MMBs antenna
65
So the POMDP policy optimization has shown better performance over the
dynamic programming approach particularly when more users are active (a greater
number of antennas as in Figure 48 the overall radiated power per BS antenna in
downlink has been considerably reduced
43 CONCLUSION AND SCOPE OF FUTURE WORK
431 Conclusion
Starting with LTE (4G) OFDMA has replaced WCDMA with mobile cellular
communications and will also be used during advanced 5G while Non-Orthogonal
Multiple Access (NOMA) has recently been recognized as a groundbreaking PHY
technology in UAV communication NOMA scheme is used in place to increase the
effective use of small resources such as in UAV communication where the data rate
is very low and critical decision making is of utmost importance
The critical need for UAV communication is a secure PHY layer for mission-
critical applications and as NOMA doesnrsquot promise high security the proposed
research work has been carried out to enhance the insecurities of NOMA-UAV
communication In this proposed research work the probabilities of confidential
outage (SOP) and OP were investigated in the two-user NOMA system Here BS is
required to pair a trusted or permissible user with other untrusted users due to the
unequal distribution of untrusted and trusted users in the cell The SIC is then
applied to the receiver side intended for decoding the message signals The Pair OP
of both users has been analyzed for varying Target Secrecy Rate (Rs) of the trusted
user U1 which provides constraint threshold of the SOP of U1
By varying the distance of Untrusted users from BS the optimal distance and power
allocation factor for the feasible pairing of trusted and untrusted users without
compromising the secrecy outage probability of U1 has been achieved in simulation
results
POMDP has provided the optimal power allocation as a resource allocation
algorithm in the dynamically changing environment of two user NOMA cases
where the distance between BS and untrusted user varies significantly The
performance of secure NOMA-UAV is affected critically by (SOP of User 1) which
66
should be optimally selected to maintain the proposed Pair OP between both users
and the simulation results have supported this optimal outage performance Thus
NOMA-UAV architecture has the potential of providing a secure PHY layer for
mission-critical applications by opting for suitable decision-making resource
algorithm POMDP
431 Scope of Future Work
Furthermore the multiuser scenario with the increased number of Untrusted users
can be analytically verified and simulated in the same direction for NOMA-UAV
communication to improve transmission security and reliability In addition more
adaptive and efficient Resource allocation algorithms for NOMA-UAV networks
with secured performance in real-time applications should be investigated
1
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Kantor I Srivastava A N Pasko D M Batla H amp Ubhi G (2017) Secure
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11
PUBLICATIONS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495449|P a g e
Migration from 4g LTE to Advanced PHY Techniques for
Unmanned Aerial Vehicle (UAV) Communication
Pankaj Patel PHD StudentGujarat Technological UniversityGujarat India
ABSTRACT
UAV (unmanned aerial vehicles) with their high mobility and low cost have found a wide range of applications
during the past few decades Historically UAVs have been primarily used in the military mainly deployed in
hostile territory to reduce pilot losses With continuous cost reduction and device miniaturization small UAVs
are now more easily accessible to the public hence numerous new applications in the civilian and commercial
domains have emerged For the sake of boosting resilience against faults natural disasters and unexpected
traffic the Unmanned Aerial Vehicle (UAV) assisted wireless communication systems can provide a unique
opportunity to cater for such demands in a timely fashion without relying on the overly-engineered cellular
network However for UAV-assisted communication issues of capacity coverage and energy efficiency are
considered of paramount importance Starting with LTE (4G) Orthogonal Frequency Division Multiple Access
(OFDMA) has replaced WCDMA for cellular mobile communications and it will also be employed in advanced
5G yet Non-orthogonal multiple access (NOMA) has been recently recognized as a promising PHY technique
to significantly improve the spectral efficiency of mobile communication networks In this paper we provide an
overview of UAV-aided wireless communications by introducing the basic networking architecture
highlighting the key design considerations as well as the new opportunities to be exploited
Keywords LTE (4G) Non-orthogonal multiple access (NOMA) Unmanned Aerial Vehicle (UAV) Wireless
communication
----------------------------------------------------------------------------------------------------------------------------- ---------
Date Of Submission 26-04-2019 Date Of Acceptance 06-05-2019
----------------------------------------------------------------------------------------------------------------------------- ----------
I INTRODUCTION The use of unmanned aerial vehicles
(UAVs) will grow rapidly in the next decade These
remotely piloted or preprogrammed aircraft are
envisioned for applications in numerous civil
settings including industrial monitoring scientific
data gathering agriculture public safety and search
and rescue Many other applications - presently
unforeseen - will inevitably also arise These
vehicles also known as the unfortunate misnomer of
drones must be integrated into the national
airspace system and into the airspace worldwide A
natural concern in the use of UAV is safety and this
has direct implications for the control and non-
payload communication systems that must be used
to operate it efficiently Similarly navigation and
surveillance functions must be made more reliable
and more accurate Because of these factors many
UAV research development testing and
standardization efforts are underway by
governments industries and academia Despite the
fact that piloted civil aircraft have been flying safely
for decades UAV presents distinct new challenges
in the form of different flight profiles eg low-
elevation flights and more high-dynamic maneuvers
wider required bandwidths eg for video and
different ground site characteristics such as locations
in cluttered areas and lower elevation antennas
In this paper first the evolution of radio
technologies considered in UAV wireless
communication is reviewed in literature survey and
the significant work in the area is highlighted along
with the newest challenges The reminder of this
paper is organized as follows
The promising technology NOMA and its
variants are discussed in section three In Section
four the system model and assumptions are
presented and in section five the comparative
analysis of NOMA with existing popular technology
OFDMA (OMA) is given with simulation
persormance analysis At last the work is concluded
in section five
II LITERATURE SURVEY Drones variously known as unmanned
aerial vehicles (UAVs) unmanned aerial systems
(UAS) or remotely piloted aircraft system (RPAS)
are used in several parts of the world for surveying
and aerial mapping disaster management work
monitoring crop production and infrastructure
activities besides commercial photography and
courier delivery The viability of UAV as a
multipurpose research vehiclehas driven great
RESEARCH ARTICLE OPEN ACCESS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495450|P a g e
interest since recent decades[1] The
basictechnology building blocks responsible for the
current advancesinclude airframes propulsion
systems payloadssafety or protection systems
launch and recovery dataprocessor ground control
station navigation and guidanceand autonomous
flight controllers The following briefsurvey is
focused on the area of navigation guidance
andcontrol of UAVs Various control design for
UAVs has beenproposed ranging from linear to
nonlinear synthesis timeinvariant to parameter
varying and conventional PID tointelligent control
approaches The developed controllershave been
implemented for different aerial platforms
airship(blimp) fixed-wing UAV small scale
helicopteruad-rotors and MAV Wireless
communication systems that include unmanned
aerial vehicles promise to provide cost-effective
wireless connectivity for devices without
infrastructure coverage Compared to terrestrial
communications or those based on high-altitude
platforms on-demand wireless systems with low-
altitude UAVs are in general faster to deploy more
flexibly reconfigured and likely to have better
communication channels due to the presence of
short-range line-of-sight links However the
utilization of highly mobile and energy-constrained
UAVs for wireless communications also introduces
many new challenges In India for the regulation
and safety purpose in commercial and survilence
applications the policy guideliens also introduced
as below
Table 1UAV communication Policy Guidelines for
commercial and surveillance purpose
III MIGRATION FROM 4G LTE TO 5G The fruitful deployment of UAV based
communicationsystems for 4G and beyond future
wireless networks is highlyinvolved in finding joint
solutions to challenge of ubiquitousconnectivity with
both a multitude of devices in a spectralefficient way
as well as with energy-efficient transmissionand
operation of the UAV-BS for maximized and
armonizedcoverage and capacity [2][3] It should be
noted that suitableenergy efficiency for the UAV-
assisted ommunication systemachieves paramount
importance in the overall performance ofthe system
Efficient energy consumption results in
enhancedairtime for the communication system
improving bitsJoulesfor a given energy level
Furthermore coverage and capacityof an aerial cell
are attributed to many factors such as
thetransmission power antenna gains UAV
altitude deploymentenvironment and prominently
radio access technology [4]
4G is the fourth generation of broadband
cellular network technology succeeding 3G and
besides the popular techniques in 3G4G ie
TDMAWCDMAOFDMA a new radio access
technology NOMA is also developed by researchers
to be used in communication networks due to its
capability in increasing the system capacity
Recently non-orthogonality based system designs
are developed to be used in communication
networks and have gained significant attention of
researchers Hence multiple access (MA) techniques
can now be fundamentally categorized as orthogonal
multiple access (OMA) and non-orthogonal
multiple access (NOMA) In OMA each user can
exploit orthogonalcommunication resources either
within a specific time slot frequency band or code in
order to avoid multiple access interference The
previous generations of networks have employed
OMA schemes such as frequency division multiple
access (FDMA) of first generation (1G)time
division multiple access (TDMA) of 2G code
division multiple access (CDMA) of 3G and
orthogonal frequency division multiple access
(OFDMA) of 4G
In NOMA multiple userscan utilize non-
orthogonal resources concurrently by yielding a high
spectral efficiency while allowing some degree of
multiple access interference at receivers Recently
NOMA reputations have climbedsharply as a
fundamental solution to the challenges
encompassingthe next generation wireless networks
[5][6]NOMA has been proved to exhibit improved
spectral efficiencybalanced and air access as
compared to OMAtechnologies[6] with the ability
to cater for multipledevices in the same frequency
time or code resource thusproviding efficient access
to massive connected devices Furthermore NOMA
is also instrumental in reducingthe interference by
employing orthogonal resources as inOrthogonal
Frequency Division Multiple Access
(OFDMA)[7][17] or by sharing a single beam
between multiple users forintra-cluster access and
using NOMA for inter-cluster access[18]Current
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495451|P a g e
studies have focused on provisioning Air to
Ground(A2G) communication services mainly
through placement op- timization under various
viewpoints in literature The performance of UAV
based communication systems hasalso been
addressed for the underlaid Device to Device(D2D)
deployment scenario This work assumed
interferenceraised by D2D network nodes without
considering the presenceof terrestrial BS
Additionally there have been a fewstudies
discussing the performance of NOMA for UAV
basedcommunication system[8] A NOMA enabled
fixedwingUAV deployment was proposed in [8] to
support coveragefor ground users situated outside
BS offloaded location
In general NOMA schemes can be
classified into two types power-domain
multiplexing andcode-domain multiplexing In
power-domain multiplexing different users are
allocated[7][8][9][6][5][1][10] differentpower
coefficients according to their channel conditions in
order to achieve a high systemperformance In
particular multiple usersrsquo information signals are
superimposed at the transmitterside At the receiver
side successive interference cancellation (SIC) is
applied for decoding thesignals one by one until the
desired userrsquos signal is obtained providing a good
trade-offbetween the throughput of the system and
the user fairness In code-domain multiplexing
different users are allocated different codes and
multiplexed over the same time-frequencyresources
such as multi-user shared access (MUSA) sparse
code multiple access (SCMA) and low-density
spreading (LDS) In addition to power-domain
multiplexing and codedomain multiplexing there are
other NOMA schemes such as pattern division
multiple access(PDMA) and bit division
multiplexing (BDM) Although code-domain
multiplexinghas a potential to enhance spectral
efficiency it requires a high transmission bandwidth
andis not easily applicable to the current systems
On the other hand power-domain multiplexinghas a
simple implementation as considerable changes are
not required on the existing networksAlso it does
not require additional bandwidth in order to improve
spectral efficiency Inthis paper the prime focusis on
the power-domain NOMAAlthough OMA
techniques can achieve a good system performance
even with simple receiversbecause of no mutual
interference among users in an ideal setting they
still do not have theability to address the emerging
challenges due to the increasing demands in future
networks andbeyond
The superiority of NOMA over OMA can
besummarized as follows
_ Spectral efficiency and throughput In OMA such
as in OFDMA a specific frequencyresource is
assigned to each user even it experiences a good or
bad channel conditionthus the overall system suffers
from low spectral efficiency and throughput In
contrary inNOMA the same frequency resource is
assigned to multiple mobile users with good and
bad channel conditions at the same time Hence the
resource assigned for the weak user isalso used by
the strong user and the interference can be mitigated
through SIC processesat usersrsquo receivers Therefore
the probability of having improved spectral
efficiency and ahigh throughput will be considerably
increased
_ User fairness low latency and massive
connectivity In OMA for example in OFDMAwith
scheduling the user with a good channel condition
has a higher priority to be servedwhile the user with
a bad channel condition has to wait to access which
leads to a fairnessproblem and high latency This
approach cannot support massive connectivity
HoweverNOMA can serve multiple users with
different channel conditions simultaneously
thereforeit can provide improved user fairness lower
latency and higher massive connectivity
_ Compatibility NOMA is also compatible
with the current and future communication
systemssince it does not require significant
modifications on the existing architecture For
exampleNOMA has been included in third
generation partnership project long-term
evolutionadvanced (3GPP LTE Release 13)
Figure 1Pictorial comparison of NOMA Vs OMA
Although NOMA has many features that
may support next generationsit has some limitations
that should be addressed in order to exploit its full
advantage set Thoselimitations can be pointed out
as follows In NOMA since each user requires to
decode thesignals of some users before decoding its
own signal the receiver computational
complexitywill be increased when compared to
OMA leading to a longer delay Moreover
informationof channel gains of all users should be
fed back to the base station (BS) but this results in
asignificant channel state information (CSI)
feedback overhead Furthermore if any errors
occurduring SIC processes at any user then the error
probability of successive decoding will beincreased
As a result the number of users should be reduced to
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495452|P a g e
avoid such error propagationAnother reason for
restricting the number of users is that considerable
channel gain differencesamong users with different
channel conditions are needed to have a better
network performance
IV NOMA UPLINK AND DOWNLINK
SCENERIO SIMULATION ANALYSIS In this section an overview of NOMA in
downlink and uplink networks is introduced
throughsignal-to-interference-and-noise ratio (SINR)
and sum rate analyses Then high signal-to-
noiseratio (SNR) analysis has been conducted in
order to compare the performances of OMA
andNOMA techniques[10]
A Downlink NOMA Network
At the transmitter side of downlink NOMA
network as shown in Fig 2 the BS transmits
thecombined signal which is a superposition of the
desired signals of multiple users with different
allocated power coefficients to all mobile users At
the receiver of each user SIC process isassumed to
be performed successively until userrsquos signal is
recovered Power coefficients ofusers are allocated
according to their channel conditions in an inversely
proportional mannerThe user with a bad channel
condition is allocated higher transmission power
than the one which has a good channel condition
Thus since the user with the highest transmission
power considers the signals of other users as noise
and recovers its signal immediately without
performing anySIC process However other users
need to perform SIC processes In SIC each userrsquos
receiverfirst detects the signals that are stronger than
its own desired signal Next those signals
aresubtracted from the received signal and this
process continues until the related userrsquos own signal
is determined Finally each user decodes its own
signal by treating other users with lower
powercoefficients as noise The transmitted signal at
the BS can be written as
s = aiPsxi
L
i=1
where xi is the information of user i (Ui)
with unit energy Ps is the transmission power atthe
BS and ai is the power coefficient allocated for user
i subjected to ai = 1Li=1 and a1gea2gehellip geaL since
without loss of generality the channel gains are
assumed to be ordered as h1 2 le h2 2 le⋯ hL 2 where hL is the channel coefficient of Lth
user based on NOMAconcept The received signal
at lth user can be expressed as follows
y1 = hls + nl = hl aiPsxi + nlL
i=1
where nlis zero mean complex additive Gaussian
noise with a variance of σ2
(1) SINR analysis By using (2) the instantaneous
SINR of the lth user to detect the jth user jle l
with jne L can be written as
SINRl = alγ hl 2
γ hl 2 aiLi=l+1 + 1
Where γ = Psσ2 denotes the SNR
(2) Sum rate analysis After finding the SINR
expressions of downlink NOMA the sumrate
analysis can easily be done The downlink
NOMA achievable data rate of lth user can
beexpressed as
RlNOMA-d
= log2 1 + SINRl = log2(1 +alγhl2γhl2 i=l+1Lai+1
B Uplink NOMA Network
In uplink NOMA network as depicted in
Fig 3 each mobile user transmits its signal to the
BS At the BS SIC iterations are carried out in order
to detect the signals of mobile users By assuming
that downlink and uplink channels are reciprocal and
the BS transmits power allocation coefficients to
mobile users the received signal at the BS for
synchronous uplink NOMA can be expressed as
r = hi aiPxi + n
L
i=1
where hi is the channel coefficient of the ith
user Pxi is the maximum transmission power
assumed to be common for all users and n is zero
mean complex additive Gaussian noise with a
variance of σ2
Figure 2Downlink NOMA network
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495453|P a g e
Figure 3 Uplink NOMA network
1) SINR analysis The BS decodes the signals of
users orderly according to power coefficientsof
users and then the SINR for lth user l ne 1 can
be given by
SINRl =alγ hl 2
γ ai hi 2 + 1lminus1i=1
where γ =P
σ2
2) Sum rate analysis The sum rate of uplink
NOMA when γ minus infincan be written as
Rsum NOMA-u asymp log2(γ hl 2L
l=1
C Comparing NOMA and OMA
The achievable data rate of the lth user of OMA for
both uplink and downlink can be expressed
RsumOMA = αl log2(1 +
βlγ hl 2
αl)L
l=1
For the sake of simplicity sum rates of
uplink NOMA and OMA can be compared for
twousers Then using both the sum rate of uplink
NOMA and OMA at high SNR can beexpressed
respectively as
RsumNOMAasymp log2 γ h1 2 + γ h2 2
Here we notice ROMA
sumle RNOMA
sum
Fig shows that NOMA outperforms OMA in terms
of sum rate in both downlink and uplinkof two
user networks
V SIMULATION RESULTS
The Comparative analysis of modelling
Downlink and Uplink NOMA in comparison with
OMA is simulated and findings are presented that
shows superiority of NOMA over OMA with better
spectral efficiency for simulation parameters taken
as power allocation coefficients a1=06 a2=04 and
channel responses h1 2
=0 DB h22=20 DB
parameters
Figure 4NOMA UPLINK
Figure 5 NOMA DOWNLINK
VI CONCLUSION This paper investigated an account of
NOMArsquos applicability for UAV-assisted
communication systems NOMA schemes are
proposed to improve the efficient usage of limited
network sources OMA based approaches that use
time frequency or code domain in an orthogonal
manner cannot effectively utilize radio resources
limiting the number of users that can be served
simultaneously In order to overcome such
drawbacks and to increase the multiple access
efficiency NOMA technique has been recently
proposed Accordingly users are separated in the
power domain Such a power domain based multiple
access scheme provides effective throughput
improvements depending on the channel conditions
The crucial need of UAV communication of
optimum utilization of available licensed spectrum
bandwidth is considered here and simulation results
taken presented that NOMA performs better than
OMA while fulfilling individual user-rate constraint
for both users The research work can be further
carried out investigating joint power and phase
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495454|P a g e
allocation of UAV nodes deployment for efficient
operations
REFERENCES [1] S M I C Y L M I Muhammad Farhan Sohail
Non-Orthogonal Multiple Access for Unmanned
Aerial Vehicle Assisted Communication in IEEE
access 2018
[2] M Mozaffari Drone small cells in the clouds
Design deployment and performance analysis in
IEEE Global Communications Conference 2015
[3] R Z a T J L Y Zeng Wireless
communications with unmanned aerial vehicles
opportunities and challenges in IEEE
communication magazine 2016
[4] I B-Y a H Yanikomeroglu The new frontier in
ran heterogeneity Multi-tier drone-cells IEEE
Communications Magazine pp 48-55 2016
[5] P K S a D I Kim Uav-enabled downlink
wireless system with NOMA access in IEEE
Globecom Workshops Dec 2017
[6] P Xu and K Cumanan Optimal power allocation
scheme for nonorthogonal multiple access with
fairness in IEEE Journal on Selected Areas in
Communications oct 2017
[7] E H a D I K S Ali Non-orthogonal multiple
access (noma) for downlink multiuser mimo
systems User clustering beamforming and power
allocation in IEEE Access 2017
[8] W S M B a M D M Mozaffari Unmanned
aerial vehicle with underlaid device-to-device
communications Performance tradeoffs in IEEE
Transactions on Wireless Communications June
2016
[9] Z D X D a R Z Z Chen An optimization
perspective of the superiority of noma compared to
conventional oma in IEEE Transactions on
Signal Processing Oct 2017
[10] M T Mahmoud Aldababsa1 and S G G K 2 A
Tutorial on Non-Orthogonal Multiple Access
2017
[11] X L Z J W a K J R L Zhu Han Delay
Sensitive Scheduling Schemes for Heterogeneous
QoS over Wireless Networks IEEE
TRANSACTIONS ON WIRELESS
COMMUNICATIONS VOL 6 NO 2
FEBRUARY 2007 vol 6 no 2 2007
[12] Z J W a K J R L Z Han A resource
allocation framework with credit system and user
autonomy over heterogeneous wireless networks
in IEEE Global Telecommunications Conference
2003
[13] N B S a P S S Chen Heterogeneous delay
tolerant task scheduling and energy management in
the smart grid with renewable energy IEEE
Journal of Selected Areas in Communications vol
31 no 07 pp 1258-1267 july 2013
[14] H L Z C a Z H Y Hu Scheduling strategy for
multimedia IEEE Transactions on Vehicular
Technology July 2016
[15] P F a K B L Y Dong High-speed railway
wireless communications efficiency vs fairness
IEEE Transactions on Vehicular Technology vol
63 no 2 pp 925-930 march 2014
[16] T R a Z H Z Chang Queueing game for
spectrum access in cognitive radio networks
IEEE Communications Letters vol 19 no 11 pp
2017-2020 June 2015
[17] Z C L T R a Z H F I Yun Hu Service
Provisioning and User Association for
Heterogeneous Wireless Railway Networks IEEE
Transactions on Communications 2017
[18] H S W Tianti Chen Optimal Scheduling for
Wireless On-Demand Data Packet Delivery to
High-Speed Trains IEEE Transactions on
Vehicular Technology vol 64 no 9 pp 4101 -
4112 september 2015
Pankaj Patel Migration from 4g LTE to Advanced PHY Techniques for Unmanned Aerial
Vehicle Communication International Journal of Engineering Research and Applications
(IJERA) Vol 09 No04 2019 pp 49-54
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Improving Of Physical Layer Insecurity Of The
Non Orthogonal Multiple Access System
Pankaj M Patel Prof Dr Chetan B Bhatt
Abstract The key aspect of the NOMA (power domain non orthogonal) is the user possibility for decoding the messages belonging to another pair users
on similar resources The method interprets a security threat especially in the case where the base station serves the users with various security
clearance or untrusted users The main aspect of NOMA is to serve the multiple users upon the similar radio resources at the minimal inter user
interference expense The system not only permits the serving of particular users with high efficient bandwidth but also permits the scheduling more type
of users than the timely available users In this study we investigated the secrecy outage probability (SOP) and OP in the both two user and multi user
NOMA system where the BS is supposed to pair a trusted or legitimate user with other untrusted users because of the un even distribution of the
untrusted and trusted users in the cell SIC the successive interference cancellation was then implemented at the receiver side for decoding the
message signals With the application of NOMA concept the study investigated the pair outage behavior under the SOP constraints on the trusted users
In specific the SOP and OP of the concerned U1 were obtained in the closed type of expressions The study also provided the understanding the
possibility of obtaining an optimal outage efficiency for pairing under the SOP constraints With certain numerical simulations the study verified the
effectiveness of the analytical derivations with respect to various scenarios
Index Terms NOMA Secrecy outage Probability Successive Interference Cancellation bandwidth channel state information etc
mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash
1 INTRODUCTION The physical layer security and non-orthogonal multiple
access was regarded as the encouraging techniques for the
processing of wireless communication network systems Today
the combination of the two significant communication methods
was studied to guarantee a spectral efficient and secure
wireless transmission Most of the prevailing works
predominantly concentrated on the optimization and efficiency
of the PLS in the existence of untrusted relay nodes and
external eavesdroppers(Arafa et al 2019a)But there occurs a
gap in the theoretical studies to describe the ease of obtaining
the enhanced efficiency in the existence of untrusted users
Recently the network traffic amount have greatly enhanced
particularly with the updated growth in IoT applications in
future To rectify the huge traffic demand upcoming wireless
networks must deliver a best spectral effectiveness and large
connectivity (Sun et al 2018) NOMA is regarded as the best
technology in which various NOMA technique exhibit similar
concept of providing several users at the similar frequency and
time The famous NOMA types are code domain and power
domain that provided enhanced efficiency when compared
with the existing techniques The paper adopted the power
domain on the basis of super position coding (transmitter side)
at the SIC (receiver side) Hence the users could possess the
key for the messages of other users and thereby utilize SIC for
removing the interference (Cao et al 2019) (Zhao et al
2018) Hence various NOMA methods was proposed for
allowing the adjacent users to perform as a relay for improving
the efficiency of the weak users through the resending of
decoded data in a next time slot The weak user could utilize
the MRC technique to integrate the information achieved in
different time slots In addition obtaining a secured
communication is a crucial problem over the vulnerable
wireless networks to security threats mainly because of the
broadcasted transmission nature
The study investigated the secrecy performance and outage
with the untrusted user(Furqan et al 2019) The main aspect
of the study is to analyze the feasibility of achieving the OP of
the pair under a trusted user Because of the decoding facility
and spectrum sharing of SIC the untrusted user could perform
as a eavesdropper
Figure 1 Representation of Base station
Figure 1 depicts the representation of base station The main
aim of the proposed system defined as
bull To investigate the outage probability of the proposed
system
bull To investigate the SOP of the proposed system
bull To derive the accurate expression of the outage
probability for all kind of scenarios and closed form of
expressions for few special cases and verifying them
numerically for yielding a better outage efficiency
2 RELATED WORKS This section describes the different existing techniques and
methods related as our proposed system (Cao et al
2019)suggested two kinds of relay selection process denoted
as AF (amplify and forward) and DF (decode and forward) on
the basis of AORS and DORS for achieving secure and
reliable NOMA systems under the untrusted users The study
derived the accurate and asymptotic closed form of the SOP
expressions and the PSCP obtained by the two methods and
investigated the optimized feature of the two methods The
____________________________________
bull PANKAJ M PATEL is currently pursuing PHD program in Electronics
amp Communication in Gujarat Technological University E-mail
pankajmphd24gmailcom
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complete analysis and the simulation results represented that
both the AORS and DORS characteristically outperformed the
benchmark system apart from obtaining the similar SOP and
the required PSCP at very high Signal to noise ratio (Zhang et
al 2018)Investigated the power allocation and joint subcarrier
issue for NOMA ndashAF two-way relay networks with restrictions
The study focused to optimize the obtainable secrecy
efficiency by designing jointly the SC task power allocation
and user pair scheduling The paper suggested a SCAS-1
technique by assuming the appropriate information about the
channel state information in the relay station followed by the
formulation of SCAS-2The secured power allocation issue is
structured as a convex programming issue and then resolved
by in-depth point techniques The results of simulation
explained that the efficiency of the suggested SSPA algorithms
with and without CJ respectively (Arafa et al
2019b)Considered a downlink system where the base station
is connecting with two appropriate users in two various
scenarios in the unsecured environments which are the
presence of the eavesdropper and untrusted relay
communication In the first process several trusted
cooperative relays is engaged for assisting with the base
station transmission and protect the corresponding signals
from the eavesdropper Several relay methods are framed and
investigated for the following process which are forward and
decode cooperative jamming and AFFor all the technique
secured beam forming signals were formulated at the relays
for maximizing the obtainable secret rate areas For the next
process with untrusted relay the obtained secrecy rate areas
obtained for two various relay schemes which are AF and CF
under two various operation modes In the first process the
prescribed users will receive the signals from the untrusted
relay and the base station for decoding the messages The
study depicted that the efficient relay scheme is highly
dependent on the parameters of the system especially the
nodal distance and the secrecy rate area (Sun et al
2018)Studied the algorithm for resource allocation for MISO
systems where the full duplex BS serve several half duplex
downlink and uplink users on the similar subcarrier The
allocation of the resource have been optimized for maximizing
the weight system output whereas the leakage of information
was restricted and an artificial noise was induced for granting
secured communication with respect to potential
eavesdroppers The study formulated a novel non-convex
optimization issue by considering the imperfect CSI of the
channels and requirements of QoS of legitimate users The
simulation results stated the efficiency of the optimal algorithm
was related to the suboptimal algorithm Apart from that the
suggested MISO NOMA technique not only guarantee uplink
and downlink communication purpose for security but delivers
a characteristic rate of system secrecy when compared with
the conventional MISO and other two baseline methods
(Dang et al 2017)Analysed the outage efficiency of various
multicarrier relay selection techniques for 2 hop OFDM system
in Poisson relay fields The study concentrated on DF relay
systems with more selection schemes The accurate
expressions for the OP are provided in integrals generally
Apart from that asymptomatic derivatives for OP in the SNR
region in the fixed circle area are predicted for both relay
selection techniques in closed forms Consequently several
significant factors that are linked to the cooperative network
were examined comprising OP ratio of two selection
techniques diversity and subcarrier optimization output In
conclusion a structure to analyze the OP of OFDM with
spatially random relay have been constructed that could be
easily altered for analyzing same case with various forwarding
protocols channel conditions and location distributors (Dang
et al 2018)Proposed a full duplex OFDM ndashD2D system in two
hop network where DF relays help the transmission from DUE
transmitter to DUE receiver The study also investigated the
OP issue by integrating the transmit power within the DUE
relays and transmitter and to deliver a suboptimal solution that
can improve the outage performance The investigations are
validated by Monte Carlo simulations These results described
could furnish an insight into full duplex OFDM system and
guides for the application in the next generation network
(Kokshoorn et al 2016) suggested a robust channel algorithm
for mmWave systems on the basis of novel overlapped pattern
design With the use of finite measurements the study
depicted that this decreased measurements was found ENR of
25 dB to obtain the similar PEEFor the appropriate channel
with quickly altering channel information the price might be
acceptable for improving the speed of estimation The study
also proposed a robust channel estimation algorithm where
the additional calculations are carried out when expecting
more estimation error The study depicted that the channel
could be measured more effectively resulting in noteworthy
gains upto 6 dB when comparing with the existing algorithm
(Ali et al 2016) described the variations in the principles of
downlink and uplink NOMA transmissions in a wireless
system The study formulated a maximization issue in a cell
like the user clustering and power allocations Because of the
integral nature of the formulated programming issue the study
solved the issue in to steps which are grouping of users into
clusters and then to optimize the corresponding power
allocations The study proposed a sub optimal scheme that
exploited the gain variations in NOMA groups and clusters into
multiple and single clusters for enhancing the sum-throughput
The results compared the efficiency of OMA and NOMA in
different network scenarios (Lv et al 2017) investigated a
MCR-NOMA where the multicast user functions as relays to
enhance the efficiency of both secondary and primary
networks On the basis of the available CSI three various
secondary user schedule techniques for processing MCR-
NOMA were depicted For evaluating the system efficiency the
study derived the closed form of expressions of OP and order
of diversity for both the networks It has been described that
more spatial temporal diversity could be obtained by using the
CSI for scheduling of the secondary user (Liu et al 2016)
considered a MIMO ndashNOMA scenario for investigating a
dynamic clustering issue in an logical perspective To resolve
the problem of optimization issue three algorithms named top
down A and B bottom up were suggested for realizing various
complexity tradeoff and worst user throughput The study
noted that the top down B algorithm could obtain a better
tradeoff between throughput and complexity amongst the
applied procedures (Fianu and Davis 2018) investigated
three various rules of allocation and demonstrated the optimal
policy as an available inventory function The study also
provided the country level estimation of requirements that are
not met and the determination of the probability distribution
linked with the total undeserved counties The study have
been done for depicting the policy of allocation with respect to
effectiveness and equity (Hou et al 2018) studied the socio
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graphical impact on the mobile video services and thereby
suggested a CTMDP on the basis of resource allocation
technique by considering social graphs as the constraints
With the use of relative value an optimized policy could be
achieved that aimed at increasing the reward regarding the
average system The simulation depicted that the suggested
CTMDP obtained an increased efficiency against the state of
art methods
3 PROPOSED WORK
Fig 2 Proposed flow depicting the overall mechanism
The proposed(Interference mitigation using POMDP) overall flow
is depicted in the figure 2 After setting up of the base station the
distance between the base station and the user was determined
and if the distance is less than 200 meters it is decided as trusted
users and if it is greater than 200 m it is defined as untrusted
users In case of untrusted users the channel state information is
subjected to POMDP (Partially observable Markov Decision
Process) followed by resource allocation The performance
analysis have been done after the system The work considered
a NOMA oriented cellular setup provided with a base station at
the centre and two users as shown in the figure 2 The adjacent
(near) user possess high level of security clearance that is
required for securing with physical layer from the low
securityuntrusted clearance user (U2) that is located at a faraway
distance from the base station P is defined as the maximum
transmit power level (base station)In this paper it is assumed that
all the network nodes are installed with single antenna and further
all the channels are considered to be identical independently
quasi static with Rayleigh distribution with respect to distribution
119862119873(0 120575 frasl
120596 frasl
) In which 120575 is the distance in-between the BS
and nodes 119880 Here path-loss exponent and path-loss constant is
represented as 120572 and 120596 In addition it is assumed that base
station predicted the user location so that a better CSI is
obtainable at base station that is involved in pairing the users
The base station transmits the superimposed mixture
119909 = radic119905 119904 + radic1 minus 119905 119904
In which 119904 119904 are the unit power signals received by users 119880 and
119880 respectively 119905 is the power
allocation coefficient for the adjacent user
119903 = ℎ 119909 radic119875 + 119899
119903 = ℎ 119909 radic119875 + 119899
where ℎ ℎ - the channel gain linked with the
small-scale fading from the base station to users 119880 and 119880
respectively 119899 and 119899 are the extra white Gaussian noise with
variance and zero mean 1198730 and it is assumed that 120588 = 1198751198730 is
the BS convey signal-to-noise ratio (SNR) In NOMA technique
farther user that possess more power
could decode its own signal by considering the adjacent signal as
a noise without decoding the adjacent user message In the
preceding equation it is assumed that U1 first decode the weak
signal followed by decoding its own signal with SICU2 which is
the untrusted user attempted to decode the near user message
after the decoding of the adjacent user messages after the
process of decoding its own message with SICHence the
following equation have been achieved
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119879119900119905119886119897 = 119878119868119873119877 119878119868119873119877
119878119868119873119877 119878119868119873119877
+
where 119878119868119873119877 represented the signal-to-interference-plus-noise-
ratio of user 119898 that was decoded by 119880 for 119898119899120598119894 2+ and the
channels gain of 119880 denoted by |ℎ |
followed an exponential distribution
with the parameter 120577 = 120596 120575
Problem Formulation
Hence the base station should achieve and serve a better
communication for the users who are susceptible to security
threat from untrusted user the proposed system defined two
kinds of QoS efficiency measures that could be regarded to be
important for framing the issue In specific the study defined a pair
of OP to check the reliability of the QoS satisfaction In general
the pair OP is stated as the probability in which the obtainable
data rates dor the users equal to or greater than the least target
threshold The next metric also called as the SOP is the
probability that the non negative secrecy capacity obtained by the
trusted user is more than the threshold value
The following issue aimed at reducing the pair OP subjected to a
SOP factor for the user U1 that is provided by
min
119875
0 lt 119905 lt 05
119878119874119875 le 120573
in which 119875 119878119874119875 and 120573 are the pair OP SOP(119880 ) and the
permissible SOP threshold
4 PERFORMANCE ANALYSIS
Derivation of the Pair OP
With the use of Shannonrsquos capacity formula and considering
119862 and 119862
as the threshold capacities of users 119880 and
user 119880 respectively the OP of the pair could be provided
by
119875 = 1 minus 119876 119909119876
in which
120591 = 2
119898 120598 119894 2+
120601 =
( )
120601 =
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119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 1 120601 gt 120601
For having 120601 gt 120601 the constraint on
the power allocation factor (t) needs to be satisfied
(119905 gt
) and for this case 119876 could be obtained as
follows
119876 = exp (
)
lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 2 120601 lt 120601
Like case 1 it was stated that opposite constraint on
a as (119905 lt
) and
119876 can be derived as follows
119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
The OP of the NOMA pair
119875 = 1 minus 119891(119905)119896 (119905)
lt 119905 lt
1 minus 119891(119905)119896 (119905) 0 lt 119905 lt
in which
119891(119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
Derivation of SOP of 119880
With Shannonrsquos capacity formula the secrecy rate of
user 119880 was provided by
119878119862 = 119869 minus 119869
119869 = log (1 + 119879119900119905119886119897 (r (1)))
119869 = log (1 + 119879119900119905119886119897 (r (2)))
119878119862 is the non-negative secrecy capacity of 119880 Provided the
secrecy capacity in the SOP of 119880 is
119878119874119875 = 1 minus 120584119890
119860 =
120584 =
119879 - the user 119880 secrecy target rate
Theorem 1
Outage-optimal power allocation factor
119905 = radic
( )
In which 119908 =
119908 =
119911 = 1 + 120591
The minimum power allocation factor (119886 )
119905 =
(
)
The optimal OP of the NOMA pair under the SOP constraint
=
( )
( ( ))119890
( )
That is lt 0whih meant that the U1 (SOP) is a reducing function
Of t that results in the optimal power allocation factor that is
greater than 119905 for the satisfaction of secrecy constraining
factorPartially observable Markov decision process S is
represented as statesLet D is the channel features which is
consider here as actions the conditional transition probability
between states is regarded as T Reward function R is
calculated as the prediction of maximum capacity channel with
respect to data rate r = R(S x D) the agent receives an
observation o ϵ 120118 o isin Ω display style oin Omega that
depended on the new environment state S and on the just
took action d with the probability O(o|s d)
Reward received at time t is conveyed as r = R(S x D)
H is the belief states over POMDP states
119867 is the belief state transition function
119903 = 119877(119867 x 119863) is the reward function on the belief states
119861 (ℎ 119889 ℎ ) = sum Pr ( 120118 ℎ |ℎ 119889 119900) Pr(119900|119889 ℎ)
Pr(h |h d o) =
1 if the belief update with arguments h d o returns h 0 otherwise
The reward function is updated on the basis of the belief MDP
r (h d) = sum h(s) R(s d) isin
the agent focus on the largest expected immediate rewardin
other words the maximum capacity channel The section
analyse the accuracy of the analytical derivations under
various settings
Figure 3 The feasible pairing
The SOP of U1 with the increasing untrusted user U2 and
distance (d2) for several BS transmits Signal to Noise Ratio
at 120588 = minus20minus1020 119889119861is depicted in with a=005 and 01 and
d1=200m is depicted in the figure The results stated that the
U1(SOP) is a gradually reducing function as per d2 that
implies that the increasing value of d2 leads to the
improvement of the SOP of U1 Since the provided constant
threshold ϵ in SOP restraint U2must be situated at a larger
space when compared with threshold value to obtain the SOP
of U1 Apart from that it is normal that the high the target
secrecy rate rises the SOP of U1
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Figure 4 The Secrecy outage probability
Feasible Pairing in th SOP of pair OP and U1 with the
enhanced power allocation factor (a) in which d2 = 700 m d1
= 200 m 120588 = 15 dB and ϵ = 01 The results depicted that the
the pair OP and SOP of user U1 with increased a for two (d2)
various distances of the (U2) untrusted user The results
approve the convex nature of the pair OP and the SOP curve
is gradually decreasing on the basis of a Generally during the
increase in a the power assigned to the weak user message
decreases that minimize the ability of U2 for discriminating the
superior positioned signals thereby improving the SOP of U1
Figure 5 The Pair outage probability
Pair OP in case of rising U2 untrusted user in distance (d2)
for different base station transfer the signal to noise ratio(120588 =
5 15 25 dB) where a = 015 and d1 = 200 m
Figure 6The infeasible pairing of secrecy outage
probability of the pair OP and U1
The infeasible pairing of SOP (U1) and the pair outage
probability with the enhanced allocation of the power ad1(200
m)d2(300 m)120588 = 15dB and ϵ = 0
The figure 6 depicted that the
The figure 6 shows the similar plotting of the data by altering
the untrusted user location by transferring it to a BS closer
distance (d2 = 300 m) It also depicted that the U1 SOP
constraint of is disrupted at a because the SOP is more than ϵ
The accuracy is well-matched and verified with all range of
numerical simulation The results noticed that the efficiency is
based on the comparative locations of the two user with the
base station
Figure 7 The figure 7 depicts that SNR versus strictly
positive secrecy rate
The observed graph proves that the secrecy capacity
outperforms the existing techniques The proposed precoding
application increases the performance of the system The
transmission power of the system is the power required to
transmit a particular data When there is an increase in the
number of users there is the possibility of inference in the data
transmission and hence the efficiency of the data rate may be
affected Depending on these instances the efficiency of the
antenna capacity to withheld and accommodate the data
determined
Figure 8 The power radiated by BS antenna
In the figure 8with respect to the simulation setup the
precoding methods are performed based on the radiated
power per BS antenna is depicted The results observed the
better efficiency of the proposed system The proposed proves
to be better when compared with existing linear precoding
methods in the prescribed three metrics thereby stating that
MRT may be utilized for the the examination of the secrecy
capacity Our proposed technique spends less radiatated
power thereby increasing the overall capacity of the system
5 CONCLUSION The NOMA system decodes the messages of other user pairs
on the similar resources thereby promoting user possibility
The technique interprests a security threat in which the BS
serves the untrusted users The study analysed the SOP and
OP in both multi user and two user NOMA system in which the
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base station pairs the trusted user in closed type of
expressions The proposed (Interference mitigation using
POMDP) also enable the understanding of possibility of
achieving outage optimal efficiency to pair under SOP
constraints The numerical verifications verified the efficiency
of the analytical derivations
6 REFERENCES [1] ALI M S TABASSUM H amp HOSSAIN E 2016
Dynamic user clustering and power allocation for
uplink and downlink non-orthogonal multiple access
(NOMA) systems IEEE access 4 6325-6343
[2] ARAFA A SHIN W VAEZI M amp POOR H V
2019a Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
15 210-222
[3] ARAFA A SHIN W VAEZI M amp POOR H V
2019b Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
[4] CAO K WANG B DING H LI T amp GONG F
2019 Optimal Relay Selection for Secure NOMA
Systems under Untrusted Users IEEE Transactions
on Vehicular Technology
[5] DANG S CHEN G amp COON J P 2018
Multicarrier relay selection for full-duplex relay-
assisted OFDM D2D systems IEEE Transactions on
Vehicular Technology 67 7204-7218
[6] DANG S COON J P amp CHEN G 2017 Outage
performance of two-hop OFDM systems with
spatially random decode-and-forward relays IEEE
Access 5 27514-27524
[7] FIANU S amp DAVIS L B 2018 A Markov decision
process model for equitable distribution of supplies
under uncertainty European Journal of Operational
Research 264 1101-1115
[8] FURQAN H M HAMAMREH J amp ARSLAN H
2019 Physical Layer Security for NOMA
Requirements Merits Challenges and
Recommendations arXiv preprint arXiv190505064
[9] HOU L ZHENG K CHATZIMISIOS P amp FENG Y
2018 A Continuous-Time Markov decision process-
based resource allocation scheme in vehicular cloud
for mobile video services Computer
Communications 118 140-147
[10] KOKSHOORN M CHEN H WANG P LI Y amp
VUCETIC B 2016 Millimeter wave MIMO channel
estimation using overlapped beam patterns and rate
adaptation IEEE Transactions on Signal Processing
65 601-616
[11] LIU Y ELKASHLAN M DING Z amp
KARAGIANNIDIS G K 2016 Fairness of user
clustering in MIMO non-orthogonal multiple access
systems IEEE Communications Letters 20 1465-
1468
[12] LV L CHEN J NI Q amp DING Z 2017 Design of
cooperative non-orthogonal multicast cognitive
multiple access for 5G systems User scheduling and
performance analysis IEEE Transactions on
Communications 65 2641-2656
[13] SUN Y NG D W K ZHU J amp SCHOBER R
2018 Robust and secure resource allocation for full-
duplex MISO multicarrier NOMA systems IEEE
Transactions on Communications 66 4119-4137
[14] ZHANG H YANG N LONG K PAN M
KARAGIANNIDIS G K amp LEUNG V C 2018
Secure communications in NOMA system
Subcarrier assignment and power allocation IEEE
Journal on Selected Areas in Communications 36
1441-1452
[15] ZHAO T LI G ZHANG G amp ZHANG C-X
Security-Enhanced User Pairing for MISO-NOMA
Downlink Transmission 2018 IEEE Global
Communications Conference (GLOBECOM) 2018
IEEE 1-6
Coursework Completion Certificate
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PhD scholar enrolled in the PhD program in the branch Electronics and
communication Engineering of Gujarat Technological University Ahmedabad
(Please tick the relevant option(s))
HeShe has been exempted from the coursework (successfully completed during
the MPhil Course)
HeShe has been exempted from Research Methodology Course only
(successfully completed during the MPhil Course)
HeShe has successfully completed the PhD coursework for the partial
requirement for the award of PhD Degree His Her performance in the
coursework is as follows
Grade Obtained in Research Methodology
(PH001)
Grade Obtained in Self Study Course
(Core Subject)
(PH002)
BC BB
Supervisorrsquos Sign
Name of supervisor Dr Chetan B Bhat
Originality Report Certificate
It is certified that PhD Thesis titled lsquoHeterogeneous Wireless Network using Non-
Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo by Shri
Pankaj Manubhai Patel has been examined by us We undertake the following
a The thesis has significant new workknowledge as compared to already
published or is under consideration to be published elsewhere No sentence
equation diagram table paragraph or section has been copied verbatim from
previous work unless it is placed under quotation marks and duly referenced
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e The thesis has been checked using (copy of originality report attached) and found
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Signature of the Research Scholar Date 17092021
Name of Research Scholar Pankaj Manubhai Patel
Place Ahmedabad
Signature of Supervisor Date 17092021
Name of Supervisor Dr Chetan B Bhatt
Place Ahmedabad
132
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1
PhD THESIS Non-Exclusive License to
GUJARAT TECHNOLOGICAL UNIVERSITY
In consideration of being a PhD Research Scholar at GTU and in the interests of the
facilitation of research at GTU and elsewhere I Pankaj Manubhai Patel has Enrollment
No139997111012 hereby grants a non-exclusive royalty-free and perpetual license to
GTU on the following terms
a) GTU is permitted to archive reproduce and distribute my thesis in whole or in part
andor my abstract in whole or in part (referred to collectively as the ldquoWorkrdquo) anywhere
in the world for non-commercial purposes in all forms of media
b) GTU is permitted to authorize sub-lease sub-contract or procure any of the acts
mentioned in paragraph (a)
c) GTU is authorized to submit the Work at any National International Library under
the authority of their ldquoThesis Non-Exclusive Licenserdquo
d) The Universal Copyright Notice (copy) shall appear on all copies made under the authority
of this license e) I undertake to submit my thesis through my University to any Library
and Archives Any abstract submitted with the thesis will be considered to form part of
the thesis
f) I represent that my thesis is my original work does not infringe any rights of others
including privacy rights and that I have the right to make the grant conferred by this
nonexclusive license
g) If third party copyrighted material was included in my thesis for which under the terms
of the Copyright Act written permission from the copyright owners is required I have
obtained such permission from the copyright owners to do the acts mentioned in paragraph
(a) above for the full term of copyright protection
h) I retain copyright ownership and moral rights in my thesis and may deal with the
copyright in my thesis in any way consistent with the rights granted by me to my
university in this non-exclusive license
i) I further promise to inform any person to whom I may hereafter assign or license my
copyright in my thesis of the rights granted by me to my university in this non-exclusive
license
j) I am aware of and agree to accept the conditions and regulations of a PhD including
all policy matters related to authorship and plagiarism
Signature of the Research Scholar
Name of Research Scholar Pankaj Manubhai Patel Date 17092021
Place Ahmedabad
Signature of Supervisor
Name of Supervisor Dr Chetan B Bhatt Date 17092021
Place Ahmedabad
Seal
i
ABSTRACT
The landscape of future fifth-generation (5G) radio access networks is
expected to seamlessly and ubiquitously connect everything and
support higher traffic volumes densely connected wireless devices and
diversified requirements on reliability latency battery lifetime etc as
opposed to the current fourth-generation (4G) cellular networks
Moreover in unexpected or emergencies (such as disaster relief and
service recovery) the deployment of terrestrial infrastructures is
economically infeasible and challenging due to high operational
expenditure as well as sophisticated and volatile environments To
address such novel issues intelligent heterogeneous architecture by
leveraging unmanned aerial vehicles (UAVs) (or commonly known as
drones) has been considered to be a promising new paradigm To
improve the system performance of UAV communication in 5G
networks physical layer techniques are of much concern as they affect
the applications of UAVs significantly In this research work security
aspects of NOMA-based UAV communication network have been
considered for optimization as physical layer security in a wireless
communication network is not as robust as wired communication due to
fading and varying SNR scenarios Here primarily two usersrsquo models
as the trusted and untrusted user communicating with BS have been
optimized for outage-optimal performance considering pair Outage
probability and Secrecy outage probability as performance metrics The
achieved results are extended to multi-user scenarios also and for the
optimal policymaking dynamic programming and Partially Observable
Markov Decision Process (POMDP) optimization approaches have
ii
been simulated and verified The simulated results have shown that
POMDP has potential consideration as a resource scheduling
optimization technique in the NOMA-UAV communication network for
providing secure and more robust performance
iii
Acknowledgment
Completing a PhD is a tough task that requires hard work and a lot of effort This is
often an overwhelming but also great experience that I would not have been able to
complete without the assistance and support of so many people Thus it is my great
pleasure to thank all those people First of all I would like to thank almighty for giving
me the strength to carry out this task I would like to deeply thank Dr Chetan B Bhatt
my supervisor for his guidance encouragement and support over these years This
research work would not have been possible without his constructive pieces of advice his
systematic guidance and his patient support thought out the duration of my research work
I would like to express my sincere gratitude to Dr Harshal A ALOORKAR and Dr
KIRAN R TRIVEDI Dr Mehul Raval my doctoral progress committee members Their
rigorous style of reviewing and constructive feedback with valuable suggestions of Dr
Prakash Gajjar Mr Hitesh Panchal and Mrs Monali Mandli who spent their valuable
time whenever required for discussing aspects of this work and provided relevant material
as well Mr Parth Modi and Mr Jagadish Patankar to initiate and inspired me a lot to
continue my work Mr Mukesh Sharma who help in maintain documents I am also
thankful to my parents and family members who always stood with me in each critical
situation and supported me endlessly I am thankful to all EC departments of various
polytechnic and degree engineer colleges for their cooperation in every possible means
Lastly I would thank all the people who directly or indirectly helped me during this very
important phase of my life
Pankaj Manubhai Patel
vi
List of Abbreviation
3GPP 3rd Generation Partnership Project
5G Fifth Generation
A2G Air to Ground
AWGN Additive White Gaussian Noise
BDM Bit Division Multiplexing
BS Base Station
BPCU Bits Per Channel Use
CDMA Code Division Multiple Access
CR Cognitive Radio
CSI Channel State Information
CNPC Control and Non-Payload Communications
CRN Cognitive Radio Networks
D2D Device-to-Device
DCP Difference of Concave Programing
DOMP Dynamic Optimization Method of Programming
FR Floating Relay
GSM Global System for Mobile Communications
HLPSL High-Level Protocol Specification Language
ICT Information and Communication Technology
IoT Internet of Things
IRS Intelligent Reflecting Surface
IMT Information Management Technology
vi
LDS Low-Density Spreading
LTE Long Term Evolution
LTE-A Long Term Evolution Advance
MCR Multicast Cognitive Radio
MI Mobile Internet
MIMO Massive Multiple-Input Multiple-Output
mm-Wave millimeter Wave
MTC Machine-Type Communication
MUSA Multi-User Mutual Access
NOMA Non-Orthogonal Multiple Access
OFDMA Orthogonal Frequency Division Multiple Access
OMA Orthogonal Multiple Access
OP Outage Probability
POMDP Partially Observable Markov Decision Process
PLS Physical Layer Security
PDMA Pattern Division Multiplexing Control
PUN Primary User Networks
QoS Quality of Service
RIS Reconfigurable Intelligent Surface
RNRF Random Near-Random Far
Rs Target Secrecy Rate
SAGIN Space-Air-Ground Integrated Networks
SIC Successive Interference Cancellation
STBC Space-Time Block Coding
vi
SBF Secrecy Beam Forming
SCMA Sparse Code Multiple Access
SOP Secrecy Outage Probability
TAS Transmit Antenna Selection
TDMA Time Division Multiple Access
UAVC Unmanned Aerial Vehicle Communication
UMTS Universal Mobile Telecommunication Systems
URLLC Ultra-Reliable Low Latency Communication
vii
List of Figures
Figure Title Page
No
11 Usage of wireless sensor network and UAV in the
hazardous disaster control
6
12 UAV network applications types with security services
architecture
8
13 UAV-assisted heterogeneous network architecture 12
14 Security problems in the UAV 15
15 Comparative analysis of NOMA vrsquos OMA 18
21 Vehicular communication NOMA system 28
22 RS-NOMA against an external eavesdropper 31
31 Downlink NOMA network 44
32 Uplink NOMA network 46
33 Multi-two user architecture of NOMA system 49
34 Flow Diagram of the proposed system 50
35 Near and Far User 51
41 Impact on Sop with increase distance between BS and user U2 60
42 Impact on Sop with increase distance between BS and user U2 61
43 Feasible pairing t Vs pair OP 61
44 Infeasible pairing t Vs pair OP 62
45 Secrecy outage probability 63
46 Pair outage probability 63
47 SNR versus Strictly positive secrecy rate 64
48 Power radiated by per MMBs antenna 64
viii
List of Tables
Table Title Page
No
11 Physical layer hazards and measures in UAV wireless
communication network
13
21 Comparative analysis 33
31 List of parameters59 54
41 Simulation parameters 59
ix
Table of Content
Sr
No
Title Page
No
I Abstract I
II Acknowledgment II
III List of Abbreviation III
IV List of Figures Iv
V List of tables V
1 Introduction 1
11 Modern technology and its needs 1
111 Long term evolution of 4G network 2
112 Migration from 4G LTE to 5G for UAV communication 3
12 UAV assisted communication in heterogenous sensor network 5
121 Introduction to UAV Communication network 7
122 Tyews of UAVs 8
1221 UAVs as flying BSs 8
1222 UAVs as aerial UBs 10
13 Unmanned aerial vehicle for 5G network 11
14 Physical layer insecurity in UAV communication network 12
141 Principles of security 13
15 Non-Orthogonal Multiple Access (NOMA) system secured
communication
16
151 Comparison of NOMA Vs OMA 16
1511 Spectral throughput and efficiency 17
1512 User fairness and higher lately 17
1513 Compatibility 17
16 Problem identification 18
17 Motivation 19
18 Aim and objective of the research 20
19 Thesis organization 21
2 Literature review 23
x
21 Integration of UAV Networks for 5G and B5G communication 23
22 UAV-NOMA in physical layer security enhancement 26
23 Research methodology 38
24 Summary 39
3 System model for NOMA-UAV communication 41
31 NOMA -UAV system secured communication for 5G 41
311 The basic scheme of NOMA 41
312 Downlink of NOMA 44
313 Uplink of NOMA 46
314 Comparison of NOMA and OMA 47
32 PLS performance metrics in NOMA -UAV communication 47
321 SOP and OP - two user and multi-user NOMA system 48
322 System Model 48
323 Partially Observable Markov Decision Process-POMDP 50
324 Problem formulation 52
33 Performance Analysis Improving PLS Insecurity of NOMA
System
53
331 The pair OP calculation 53
332 Pseudo-code for the proposed algorithm 55
34 Summary 57
4 Result and discussion 58
41 Performance measure of secured NOMA-UAV communication
model
58
42 Numerical result and discussion 59
421 Feasible amp Infeasible pairing of trusted amp untrusted
users
60
422 The secrecy outage probability and pair outage
probability
62
423 SNR versus strictly positive secrecy rate 63
424 Power radiated by per MMBs antenna
64
43 Conclusion and scope of future work 65
431 Conclusion 65
432 Future scope 66
xi
5 References 67
8
Publications 78
1
CHAPTER -1
INTRODUCTION
11 Modern technology and its needs
Mobile technology has undergone various generational shifts transforming the
cellular framework into a worldwide set of interconnected networks In recent days
the fifth generation (5G) has delivered voice as well as video streaming It has a
very complex range of networking services for more than nine billion users and also
billions of devices that will be connected (Hu 2016) However 5G offers a new
outlet for reflection It involves a radial network architecture for the installation of
communication-type machines 5G network can also include powerful support
applications with widely varying operating parameters 5G is a blend of network
technologies that have been developed The new 5G technology will be able to
exchange information anywhere every time for the benefit of people enterprise
and society and technical environments using a restricted access bandwidth to
carry data Now it is more than a modern series of technologies and as opposed to
previous generations would entail tremendous infrastructure or machinery
upgrades This technology aims to expand on the advances that telecommunications
systems have already achieved The projected standards of efficiency that
technologies would need to resolve are
bull Five times reduce end-end latency
bull Ten to a hundred times the higher complex rate of user data
bull Battery life is ten times longer
bull 10 to 100 times higher number of connected devices
In this research work the UAV-assisted communication over the 5G network has
been proposed with enhanced physical layer security aspects NOMA has been
proposed as the reference framework architecture for UAV communication as one
of the recent popular 5G techniques Along with the advantage of suitability in UAV
communication network NOMA has the disadvantage of insecurity in the physical
layer Here the migration of Long Term Evolution (LTE) to advanced physical layer
2
security for Unmanned Aerial Vehicle communication (UAV) over 5G network has
been proposed and also improve the insecurity of Non-Orthogonal Multiple Access
(NOMA) System We will discuss in the further chapter the proposed work This
chapter describes the introduction and basic concepts of the 5G networks with
methodology techniques and types It states the problem identification motivation
and further aim and objective of this work
111 Long Term Evolution of 4G Network
LTE is customary for 4G wireless broadband trends that provide improved network
capability and gives mobile device users speed It offers high peak data transform
rates in the range of 100 Mbps and 30 Mbps downstream and upstream
respectively It provides a capacity of scalable bandwidth mitigated latency and
backward compatibility with the previous Global System for Mobile
Communications (GSM) and Universal Mobile Telecommunication Systems
(UMTS) technology
The fourth development of cellular networks (4G) has already been developed to
meet the standards of the 3G and 2G families Every 10th year a new mobile
generation claimed to be familiarized with the first 1G system in 1981 tracked by
the 2G system that went on to roll out in 1992 and 3G launched in 2001 growth in
the year 2002 of 4G networks The actual new revolution began in December 1998
with the 3rd Generation Partnership Project (3GPP) With high-quality video and
images 3G networks are designed for multimedia networking with them Peoples
communication can also be enhanced and connectivity to public and private
network information and resources has improved with higher frequencies and new
flexible communication features third-party device applications
With the start of LTE-Advanced several vital demands and improvements are
beginning to emerge Various importance purposed for LTE-Advanced can be
exemplified as follows (Abed)
bull Provides spectrum output with LTE delivered more than three times
bull Spectrum can help scalable bandwidth and convergence of the spectrum
where it is necessary to use a non-contiguous range
3
bull Provides uplink and downlink spectrum output that varies between
15bpsHz and 30bpsHz
bull The edge throughput must be twice that of the user cell in LTE
bull From idle status to connected status the communication latency scenario is
smaller than 50msec and less than 5msec for direct packet transfer
bull Any users total throughput must be three times that of LTE
bull LTE advancement will provide 3GPP as well as LTE compatibility via inter
networking
bull The mobility conditions that are used in LTE are identical
The latest LTE advanced requirements are not yet included in device
specifications there are high-level purposes Before it is fixed in the specifications
and needs to be tested much effort remains to be approved
112 Migration from 4G LTE to 5G for UAV communication
The productive implementation of a UAV communication network in 4G and the
upcoming wireless network is included in identifying combined solutions to test
the correlation with both multitudes and also energy-efficient transmission Then
the process of the UAV-BS to optimize coverage and power It is stated that the
energy efficiency of the UAV-aided communication system is needed Efficient
energy utilization contributes to increased air time in the contact system and
increased joulesbits at a provided energy level Also aerial cell coverage and
ability may be because of various parameters such as antenna gains transmission
strength radio access technology UAV altitude and deployment environment
4G is the fourth generation of network infrastructure technologies to replace 3G and
in addition to the popular 3G4G methods Code Division Multiple Access
(CDMA) Time Division Multiple Access (TDMA) and Orthogonal Frequency
Division Multiple Access (OFDMA) Researchers are designing the latest Non-
Orthogonal Multiple Access (NOMA) technologies to be used because of their
capability to improve the performance of communication networks Non-
4
orthogonality-based device designs have recently been developed for use in
communication networks and drawn considerable interest from researchers
Henceforth Multiple Access (MA) methods can be sub-divided as OMA and
NOMA Each user may utilize orthogonal communication resources to determine
multiple access interference inside a frequency band code and time slot in OMA
Its methods such as First generation (1G)- FDMA 2G -TDMA 3G -CDMA and
4G - OFDMA have been used in previous network generations In NOMA by
producing a higher spectral efficiency however enabling some amount of multiple
entree intrusion in receivers and multiple users may use non-orthogonal resources
simultaneously Recently the credibility of NOMA as a solution to the problems of
the next generation of wireless networks has been increased Compared with OMA
technologies NOMA has been described to improve spectral quality be well-
adjusted with air connectivity and can provide accommodations for multiple
strategies at the same time of frequency Therefore enabling excellent progress to
massively correlated devices
In particular NOMA also affects mitigating interference by using OFDMA as an
orthogonal method or through offering a standard intra-cluster access beam across
multiple users and inter-cluster access in NOMA Recent studies have concentrated
primarily on the provision of Air to Ground (A2G) connectivity services through
optimization of a different point of view
The output of the UAV-based communication network was discussed in the Device
to Device (D2D) implementation setup The proposed system hypothesized
interference caused through D2D network nodes deprived of acknowledging the
occurrence of global BS Also several studies addressed the efficiency of NOMA
It permitted the deployment of fixed-wing to assist coverage in-ground user located
outer location of offloaded BS
NOMA systems are divided into two categories namely code domain and power
domain multiplexing In the power domain user accounts are allocated to different
power coefficients as per their channel complaint to reach optimal device
efficiency Multiple user signals are applied to the side of the sender Then on the
received signal Successive Interference Cancellation (SIC) is implemented to
decipher signals in sequential order until the predicted signal is achieved offering
5
a good trade-off between efficiency of the system and user fairness Different code
domain multiplexing is Sparse Code Multiple Access (SCMA) Low-Density
Spreading (LDS) and Multi-User Mutual Access (MUSA) Compared to power and
code domain multiplexing there are alternate NOMA techniques such as Bit
Division Multiplexing (BDM) and Pattern Division Multiplexing Control (PDMA)
However this multiplexing is capable of improving the efficacy of spectral It
requires a large transfer of bandwidth which is not appropriate for new methods
But on the other side the power domain has direct execution since there is no need
for significant improvements to the current networks It also does not necessitate
bandwidth to increase spectral efficiency In this chapter the main emphasis
depends on the power domain NOMA While OMA strategies can produce the best
results also with necessary receivers due to no mutual intervention among users in
an optimal situation they cannot even resolve increasing problems due to growing
demands on connectivity growth and even beyond
12 UAV assisted communication in heterogeneous sensor network
Wireless communications had created a golden chance for urban and rural
territories The LTE (Long term evolution) and LTE-A (Long term evolution
Advance) had offered the service (with QoS) for all customers through wireless
The traffic properties in the machine type communications (MTC) and the
accumulation of the MI (Mobile Internet) had made the difficulty of implementing
the cellular communication networks Installing base stations was impractical in the
urban areas due to its cost To overcome this issue the UAV suggested that it
contains the merits of compatibility and high battery life and is affordable Most of
the devices like the sensor nodes and professional cameras had been used in UAV-
assisted networks Here the UAV-assisted floating relay (FR) was launched in the
cellular communication networks UAVs were implemented more with WSN
(wireless sensor networks) The base stations were adopted with the UAV So the
MI and MTC traffic challenges were controlled (Yue Li amp Cai 2017)
UAV-assisted Heterogeneous networks had implemented in vast practical
applications UAV helped heterogeneous networks were applied in the military
department In the military the UAV had examined and surveyed the opposing
6
countryrsquos activities for security The UAV-based heterogeneous networks were
used in the military sectors where a novel authentication scheme was introduced
As The one-to-one communication via WSN was considered as secured
communication WSN had the disadvantage of consuming power The
authentication was implemented in the tool of Automated Validation
of Internet Security Protocols and Applications (AVISPA) in which the expression
had been written in the High-Level Protocol Specification Language (HLPSL)
programming language The authentication had evaluated between the user and the
base station Similarly the authentication between the user and the UAV was
calibrated The citizen and economic safety are predicted and conserved through
reliable communication in the military by obtaining foes exploration information
The faithful secured communication was confirmed using AVISPA (Rashid et al
2019)
Figure 11 Usage of wireless sensor network and UAV in the hazardous
disaster control
The integration of the wireless sensor networks and the unmanned aerial vehicle
UAV was analyzed and applied to manage the natural disaster illustrated in Figure
11 The aircraft can prevent the fire spreading drop sensors the temperature map
and biodiversity map by sensors the wildfire can easily route The wild animals can
7
be tracked and the dynamic data of moving animals can be gathered by WSNs The
biologists can fix the sensor in the animals collar the radiation that positively
affects humans can be observed in affected areas The WSNs help to prevent heart
attack of a person by monitoring heart rate The state of health can be known
through a message alarm using a GPRS system
The cooperative networks of WSN and UAV were implemented in the military
sector for the advantageous feature The UAV was providing good connections
overlapping and overall data rate The conventional UAV method aided sensor
networks concentrated only on the single tasks of monitoring accumulating
information and localization The multi-UAV had not been implemented in the
sensor networks The animal colony perception technique was utilized for
scheduling the resourced and the target assignment Functions of multi-data were
used for localization by the target recognition method (Gu Su et al 2018)
The Physical Layer Security (PLS) was achieved through 5G technologies delicate
coding for the PLS dense MIMO multi-input multi-output mm-Wave frequency
band using heterogeneous sensor networks NOMA and full-duplex mode of
communication IoT and Machine-type communications (MTC) emerged in the 5G
systems (Wu et al 2018)
121 Introduction to UAV communication network
The usage of the UAV will develop more in the next era These pre-programmed
aircraft are intended for applications in several civil settings as well as industrial
visualization agriculture rescue and search and then receiving of scientific data
These devices are called the unsuccessful inaccuracy of drones which must be
incorporated into the system of national airspace as well as worldwide The usage
of UAVs in the neutral form is always secure It has a direct inference for the control
and a payload communication system that is utilized to function effectively
Similarly surveillance and navigation operations must be made more accurate and
consistent Due to these critical factors many kinds of research in a UAV testing
development and standardization difficulties are undergone through industries
education and governments
8
Even though civil aircraft had been operating for many years yet UAV offers new
consequences in terms of various flight profiles For example high dynamic
maneuvers and low elevation flights need bandwidth video and different ground
site characteristics namely clutter locations and elevation antennas which are low
This chapter explains the core topic of the proposed work The migration of LTE
4G towards the advanced one of the physical layers for UAV communication It has
higher mobility and lower expense identified in a broad range of applications
122 Types of UAVs
The UAVs have a two-network application with security services such as UAVs as
Flying Base Stations (BSs) and UAVs as Aerial BSs in the presence of
eavesdroppers
(a) UAVs as Flying BSs (b) UAVs as Aerial mobile UEs
Figure 12 UAV network applications types with security services
architecture
1221 UAVs as flying BSs
The required infrastructure can be destroyed in natural disasters particularly
tsunamis earthquakes and snowstorms and the requisite emergency data traffic
cause both overloading and congestion of neighboring mm-Wave (Zeng et al
2016) A capable explanation is to rapidly introduce low-altitude UAVs as flying
9
BSs in such a network breakdown to improve the communication infrastructure to
mitigate cell congestion or site failure thus creating a small aerial cell
In this situation wireless communications can occur in an ad-hoc manner with
UAVs to UEs UAVs to UAVs As highlighted in Figure-12 (a) and control
stations of UAVs to ground It will increase capability dramatically and enlarge the
target of wireless networks in provisional measures as it is possible to create LoS
communication links among UAVs and UEs supported on the ground Yet form an
operating aerial cell system to monitor ground segments of UEs mobility which is
more stable to minimize sporadic connectivity on the other side
Also this can be expanded to allow several UAVs-BSs to be deployed to increase
the exposure area for supporting a wide range of UEs A network period various
UAVs-BSs is entirely independent A new paradigm was introduced through
collaboration between UAVs-BSs to extend the feasibility for a single UAV from
either a stand-alone active sensor to a wireless network over the next generation
There is a growing concern about the privacy problem in tandem with the brief
introduction of this network Wireless protection is the central issue of the
communication level wherever eavesdropping subsidizes for deliberately listening
to a source of secret information which harms the extensive placement of UAV-
BSs
A UAV-BSs is to mount several antennas in the UAV-BSs the benefits of multi-
antenna innovations geographical degree of freedom that offers an ability for UAV-
BSs to transmit eavesdropping airborne beams
Notice that in UAV systems multi-antenna technology can be technically applied
while directly modifying the separation of the antennas The existing system has
shown that transmitted beam forming models can significantly boost the
confidentiality efficiency of wiretap channels for multiple antenna transmitters
Noise may be inserted with the signal to substantially degrade the acknowledged
SINR at the eavesdroppers to prevent the information overflow
10
1222 UAVs as aerial UEs
This has already been demonstrated by reaping the benefits of Wi-Fi and LTE
technologies through field trials (Van der Bergh et al 2016) UAV-UEs typically
get their tasks for a variety of convincing IoT applications mainly in air freight
services like the google wing project Unlike conventional land base package
delivery but UAV delivery has distinctive merits such as
bull Acceleration of land transport as UAVs are not liable to road jams
bull Connection to areas that are difficult to reach
bull Decreasing the use of capital about workforce and electricity
UAV distribution is significantly dependent on having reliable and secure wireless
communication among UAVs and ground BSs especially if the UAV needs control
outside LoS the UAV-UEs are used which can develop LoS connectivity to cellular
BSs The UAV-UEs on the one hand provides high-speed access to data as it can
fly continuously in either direction On the other hand the installation of UAV-UEs
can lead to significant interference with the ground BSs in the execution of their
missions
A wide-scale installation of UAV-UEs is only feasible for this reason if the issues
of interference management are tackled It is widely known that interference
negatively affects wireless networks As highlighted in Figure-12 (b) indeed aerial
and ground UEs are served through a cellular network with a possible eavesdropper
that tries to intercept the message intended for permissible basic UEs
A cost-effective approach is to be used for coordination among ground BS and
UAVs to enhance secure transmission which is part of the UAVs acting as friendly
transmitters to degrade the wiretapping channels efficiency and thus enhance
secrecy efficiency A UAV acting as a mobile jammer can dramatically and
dynamically change its position as near as possible to the earth eavesdropper and
distribute them by sending the radio signals whereas strong LOS connection
characteristics are a beneficial feature with less earthly fading and shadowing
impairment
11
13 Unmanned Aerial Vehicle for 5G Networks
UAVs have technologically advanced as a revolutionary movement in delivering
pervasive connectivity from either the platforms of the sky as aerial
communication particularly for temporary User Equipment (UEs) (B Li et al
2019) Due to fully controllable UAV flexibility through miniaturization as well as
continuous cost reduction low-altitude UAVs are rapid and flexible designed for
operation and reconfiguration They are probable to have higher Line-of-Sight
(LoS) ties to ground UEs
A broad range of applications like inspection of infrastructure precision farming
and disaster area monitoring is becoming accessible in this aspect Moreover
further projects have also been set up to employ aerial platforms for broadband
access to distant elements such as the Google Loon and the Facebook Drone Project
to mention Highly populated UEs are desperate for broadband wireless
communications with the coming 5G period and network providers are supposed
to maintain numerous networks with high demands for wireless data like
multimedia streaming and also video downloads The relentless growth in the
amount of traffic of mobile networks puts a burden on operators in the form of
higher capital and operational expenditure Deploying small cell networks is an
intuitive alternative to outsource cellular traffic
Although in unforeseen or temporary events as mobile environments are
complicated volatile and heterogeneous the implementation of terrestrial
infrastructures is difficult The accessibility of aerial access points to enable
extensive complex connections is one possible solution However in unforeseen or
temporary events as mobile environments are complicated volatile and
heterogeneous the implementation of terrestrial infrastructures is difficult The
accessibility of aerial access points to enable extensive complex connections is one
possible solution UAV communication performance benefits from the simplicity
of the compact transceiver and progressive control methods that obtain broad
exposure and set up internet networks
12
Figure 13 UAV-assisted heterogeneous network architecture
The above Figure 13 is depicted to build flexibility of the network with enhanced
ability and elasticity It is a good network that offers security endowment This is
due to the transmitting information to UAV communication which is tapped
through ground unauthorized user and is known as an eavesdropper
Here through eavesdropper based on the upper layer cryptographic techniques
wireless communication in contradiction of unauthorized access has been protected
However it is very tough to achieve because of key management as well as more
computational difficulties in developing network architecture PLS affects the
characteristics of intrinsic wireless networks as a fascinating preparation such as
interference noise fading loss collecting signal characteristics in malicious
eavesdroppers and techniques of signal processing
14 Physical Layer Insecurity in UAV communication network
Jamming is either a well-defined WSN attack on a physical layer It disrupts the
radio waves being used by nodes of the network The attacker successively
expresses the denial of the simple MAC protocol over the wireless network The
impressive network can be disrupted at which a single frequency is being used
13
throughout a network (Modares et al 2011) In addition jamming can increase
energy consumption in the node by inserting impudent packets The receiver nodes
will also generate resources when receiving the packets In (Jeon 2006) four
different terms of jamming attacks that an intruder could use to interrupt the
wireless network activity Tampering is yet another physical layer assault
Table 11 Physical layer hazards and measures in UAV wireless
communication network
(Kumar et al 2014)
Hazard Security measures
Jamming Channel blacklisting and hopping
Interference Channel hopping and blacklisting
Tampering Security and key modification
Sybil Physical security of the system
Table 11 describes physical layer hazards and their security measures in WSN
which tampering and jamming are considered as the main attack in the physical
layer in WSN
141 Principles of security
The security requirement of UAV communication network is as follows (Kumar et
al 2014)
Confidentiality Ensure that only the approved sensor nodes could get the contents
of the texts
bull Authentication Ensure that the data is introduced from the sound source
bull Integrity Ensure that every received text has not been modified to be sent
by unauthorized users
14
bull Freshness Make confirm that no old information has been reiterated
bull Availability services are feasible at any time through WSN or by a single
node
The standard attacks of the physical layer are as follows (Sastry et al
2013)
bull Jamming The transmission of the radio signal can interfere only with radio
frequencies used through WSN which is known as jamming As the
capacity grows it may influence more significant portions of the network
by transmitting other radio signals The opponent will use a few nodes to
occupy the entire channel This state is called physical layer jamming which
results in a denial of service In this scenario the opponent will not be
permitted to have any knowledge but will be capable of preventing
communication to any nodes
bull Tampering Often the nodes tampered through an opponent This mode is
called tempering Here the attackers can destroy exchange and
electronically confront nodes to obtain information from counter measures
towards jamming that have been planned as spread as well as frequency
hopping
bull A security mechanism is used in WSN to track avoid and recover from
security attacks A wide range of security schemes can be devised to counter
malicious threats which can be classified as high and low levels
bull Secrecy and Authentication Most network sensor applications need
protection from eavesdropping packet alteration and injection Early
networks are used for connection layer cryptography as this approach offers
the easiest deployment of network cryptographic solutions
bull Privacy Like all other conventional networks the radio networks have also
brought secret issues to allow Initially sensor networks are implemented
for legitimate purposes and can eventually be used unexpectedly
Knowledge of active sensor nodes as well as the acquisition of data is
exceptionally crucial
15
bull Critical launch and trust setup The primary prerequisite for setting up a
network is the development of keys (cryptography) Sensor devices
typically have minimal computing capacity and public cryptographic
primitives are too difficult to adopt Critical establishment and strategies
need to be scaled to network with thousands of nodes
bull Secure routing Routing as well as data forwarding is a problem that
confronts to facilitate communication in networks Regrettably the latest
protocols encounter a variety of security flaws
bull Robustness of communication Does An opponent challenges to interrupt
the operation of the network
Figure 14 Security problems in the UAV
Figure 14 illustrated the security difficulties in a UAV The physical layer security
in the UAV wireless networks was examined The UAV had affected by both active
eavesdropper and passive eavesdropper This paper proposed the trajectory design
and cooperative UAV for constraining the eavesdropper NOMA MIMO mm-
Wave frequency band in UAV would cause better spectral efficiency and security
(Xiaofang Sun et al 2019)
UAV implementation of the 5G communication was considered advantageous The
UAV was assumed as the novel wireless network technique for the territory users
and their base stations The UAV had resulted in high altitude So the UAV had
16
considered a superior line of sight At the same time the possibility of security
problems was raised in a UAV The secrecy in the existence of eavesdropper the
jammer in the ground was performed using the UAV UAV aided territory security
was proposed The UAV was involved in inspecting the eavesdropper and hazard
jammers on the base stations territory UAV had targeted the global position system
spoofing for assisting the authentic users and performed the role of an artificial
eavesdropper for excluding the eavesdropper and jammers in the ground (H-M
Wang et al 2019)
15 Non-Orthogonal Multiple Access (NOMA) System Secured
Communication
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
151 Comparison of NOMA Vs OMA
Comparison of the NOMA and OMA can be discussed as follows
17
1511 Spectral throughput and efficiency
In OMA a resource is allotted to the distinct user whether it is good or bad in a
channel scenario like OFDMA Thus the whole process moves from less
throughput and performance
While the same frequency is allotted to the multiple-use at the same time with good
or bad channel operation in NOMA here the weak user gets the allocated for the
resources which the strong user can also use it And the interference can be reduced
by the SIC process on the receptor side of the user Consequently the probability
with the increased spectral efficiency as well the high throughput will be
maximized
1512 User fairness and higher lately
A user of fair channel complaints has higher precedence to be served in OMA In
contrast a user with a poor channel complaint is to remain activity which causes
the issue of user fairness and higher latency Yet OMA cannot assist colossal
connectivity Whereas NOMA helps multiple users with various channel
procedures and offers increased fairness massive connectivity and lower latency
1513 Compatibility
NOMA has compatibility with the current and upcoming scenario meanwhile no
need for necessary changes to the previous methods As an instance NOMA has
been bought up in the 3G Partnership Project LTE Advanced (3GPP LTE) Though
NOMA contains many characteristics that can assist the upcoming generations and
it has some restrictions that can be explored with its full benefits Those restrictions
are as follows
bull Each user has to decrypt the signals of other users until decrypted their
signal the complexity of the receiver would be strengthened in NOMA as
opposed to OMA which creates a long pause
bull Also data on channel quality for all users should be returned to the BS but
this results in substantial CSI input overhead Furthermore if any issues
arise to any consumer during the SIC process the likelihood of consecutive
decrypting errors will be improved
18
Figure 15 Comparative analysis of NOMA vrsquos OMA
As an outcome the number of users is reduced to ignore the spread of such
debugging Another aim of restricting the number of users is that there must be
substantial variations in channel revenues between users with different channel
grievances to provide network reliability
16 Problem Identification
The NOMA-based architectures main feature is to configure trusted and untrusted
users when more than one eavesdropper is present in the dense setting of todayrsquos
and future sophisticated wireless communication networks This research aims to
examine the security efficiency suggested for mission-critical applications in the
NOMA-based UAV communication network The proposed system underpins two
user NOMA frameworks The possibility of paring both users was explored with
PHY performance measures in mind Outage probability (OP) and Secrecy Outage
Probability (SOP) Dynamic Optimization Method Programming (DP) and Partially
Observable Markov Decision Process (POMDP) optimization have also been
analyzed to explore the feasibility of achieving an outage-optimal output for the
pair under the heavy users secrecy outage restriction The optimized theoretical
findings are applied to the multiuser scenario The identifications were tested
through a computer model in which POMDP has shown substantial progress over
the dynamic optimization method to program
19
17 Motivation
Unmanned aerial vehicle (UAV) wireless communications have experienced an
upsurge of interest in both military and civilian applications due to its high
mobility low cost on-demand deployment and inherent line-of-sight air-to-ground
channels However these benefits also make UAV wireless communication
systems vulnerable to malicious eavesdropping attacks
Despite the promising gains brought by UAVs the open nature of air-to-ground
wireless channels makes secure information transfer a challenging issue
specifically on the one hand information signals transmitted over wireless LoS
channels are likely to be intercepted by some undesired receivers which lead to a
risk of information leakage On the other hand wireless UAV transceivers are
vulnerable to malicious jamming attacks Hence security plays an extremely
important role in UAV wireless communications Unfortunately traditional
encryption techniques require high computational complexity leading to a large
amount of energy consumption which may not be suitable for UAV systems As an
alternative physical layer security is computationally efficient and effective in
safeguarding wireless communication networks via exploiting the inherent
randomness of wireless channels As a result various physical layer techniques
have been proposed in the literature for guaranteeing communication security
NOMA is viewed as a promising technique to provide superior spectral efficiency
by multiplexing information signals at different power levels [13] Hence it is
expected that NOMA can bring additional rate and robustness to enhance the
achievable rate in UAV physical layer security communications Consider a
scenario where a UAV acts as a relay to facilitate data delivery to two receivers
with different security clearance levels within a maximum cruising duration T The
receiver with a lower security clearance level and a higher potential with an
eavesdropper Since it has a strong motivation in intercepting signals intended for
a receiver with a higher security clearance Then when the eavesdropper suffers
from a bad channel condition NOMA is adopted to forward both confidential and
public information simultaneously Otherwise UAV only broadcasts the public
information for security issues The mode selection between NOMA and unicast is
20
chosen based on the results of the proposed resource allocation optimization In
particular for maximizing the spectral efficiency one needs to jointly optimize the
transmission scheme resource allocation and UAVrsquos trajectory However the
coupled optimization variables generally result in non-convex optimization
problems which are difficult to solve optimally As an alternative an iterative
suboptimal algorithm based on successive convex approximation can be employed
to facilitate a computationally efficient joint design We have discussed that the
NOMA scheme always outperforms OMA in all the considered scenarios which
demonstrates the spectral efficiency advantage brought by NOMA in striking a
balance between public data rate and confidential data rate
The main motive of this research is to enhance the inherently insecure PHY layer
of the NOMA-based UAV communication network NOMA-UAV communication
network requires feasible paring between trusted amp untrusted users (attacker) for
cooperative communication mainly in real-time field applications The power
allocation factor need to be optimized as per the trustworthiness of the associated
users (reliable user) and keeping the outage probability minimum for secured and
cooperative communications The pair Outage Probability and the SOP have been
optimized jointly for feasible pairing between BS amp the associated Users
18 Aim and Objective of the Research
The proposed works main objective is to examine the design of a NOMA-based
UAV communication network for enhanced Physical Layer security (PLS)
features Remarkably it is anticipated infrastructures and resources to connect
numerous devices and provide various services Researchers these days
concentrating on ways to design a heterogeneous framework like deployed small
cells air and ground-based deploy multifarious communication methods in 5G
such as millimeter-wave (mm-Wave) device-to-device (D2D) massive multiple-
input multiple-output (MIMO) Cognitive Radio (CR) and so on for improving
spectrum and energy efficiency
As a critical need especially for emergency applications the adoption of NOMA
transmission of UAV communication needs to be improved PLS A new optimal
resource allocation algorithm for some more robust and stable communication in
21
single and multiuser scenarios has been suggested here The PLS in dense
heterogeneous sensor networks has improved by the feasible pairing of trusted and
untrusted users (K Cao 2019 T Zhao 2018) In the instance of untrusted users
dynamic programming and POMDP are subjected to the channel conditions
details optimizing OP and SOP as a restricted parameter accompanied by resource
allocation (Davis 2018 L Hou 2018)
The main aim of the proposed research work areas
bull To analyze the underlying NOMA UAV communication framework with
enhanced Physical Layer security (PLS) implications for particular quest
applications
bull To examine the potential pairing of trusted and untrusted users in the
NOMA-based UAV contact network with two users and multiuser scenarios
for certain channel conditions called Channel State Information (CSI)
bull To maximize resource allocation among trusted and untrusted users by
pairing OP and Secret Outage Probability (SOP) as performance measures
with the POMDP optimization method
bull To evaluate POMDP and dynamic programming resource allocation with
two users and multiple users for both protected NOMA-based UAV
communication network scenarios
19 Thesis Organization
Chapter 1 Provides the introduction and basic concept of the proposed work with
the problem identification motivation and aim and objective of the proposed work
Here we described LTE 4G and its advanced techniques than about the NOMA and
its basic scheme UAV concepts represent their types and basic working strategy
Chapter 2 Provides a survey of the existing technologies which is related to the
proposed work The NOMA transmission schemes Merits and De-merits related
to security UAV assisted communication in heterogeneous sensor networks UAV
networks of 5G and beyond communications has been explained then about UAV-
NOMA PHY secured communication techniques as well
22
Chapter 3 Describes the proposed work of improvement of physical layer
insecurity of the NOMA The overflow and its performance measures with
simulated output have been defined in this chapter
Chapter 4 Describes Migrations proposed work from 4G LTE to advanced PHY
techniques for UAV communication The overflow and its performance measures
with simulated output have been explained in this chapter Concludes and explains
the proposed work with its outcome and the future scope of the proposed work
23
CHAPTER 2
LITERATURE REVIEW
21 Integration of UAV Networks for 5G and B5G communication
5G and B5G had been anticipated to give a unique connection among universal
users The UAV had been emerged for its advantage of wireless network and
relaying high data rate The UAV in the 5G and B5G was introduced and 5G and
B5G were updated with the new concept of Space-Air-Ground Integrated Networks
(SAGIN) Three layers were established named physical network communication
link and evaluation Besides the usage among the dense population IoT was
applied in satellite communication In which the IoT had provided the uninterrupted
service with high data rate communication The scope for flying UAVs had been
created for enhancing the number of mobile users with IoT (Ali et al 2018)
5G and B5G had projected the UAV as the vital constituent One to multiple point
transmission can be possibly advance in 5G and B5G The structural design of the
upcoming UAV (multi-tier drones) was driven by the routine of different structures
like the maximum functioning altitude communication overlap coverage and
determination The UAVs practicability (multi-tier drones) among conventional
UAVs (single-tier drones) is scrutinized in that perspective By ascertaining the
circumstances UAV (multi-tier drones) could supplement the older terrestrial
networks with RF Initially UAV (multi-tier drones) and drone-aided wireless
networks were related to finding the tasks The modified UAV (multi-tier drones)
and the drone-administered wireless networks were analyzed The enactments of
UAV (multi-tier drones) were scrutinized in the contest of spectral efficiency in the
downlink networks Their effect had exhibited the detailed network parameters The
UAV distribution (multi-tier drones) was considered advantageous for the spectral
efficiency from the downlink transmission over traditional terrestrial wireless
networks (Sekander et al 2018)
The growth of 5G and B5G wireless networks prominently hang on the
incorporation of the terrestrial and aerial systems in innovative heterogeneous
network architecture They had advanced a creative and tangible multiple UAV
24
made up of cluster UAV ndash base stations and Poisson point process with UAV and
mm-Wave frequency band Ground user equipment and UAV had exhibited as the
Poisson cluster process and then spread around the public cluster in the distinctive
cluster In particular the scrutiny was accompanied by the accumulation of extra
tiers Extra tiers were made up of multi-cluster UAV base stations and single ground
user base stations in the characteristic cluster Four-tier network systems were
designed correspondingly from the subdivision of the above-said base stations
Two-tier and four-tier association patterns were built for discovering the
involvement of the cluster networks The coverage probability for the downlink and
network throughput was derived (Ji et al 2020) The numerous subordinate title
role of the multifaceted communication systems was performed by the UAVs The
UAV was acted as the air relay in the maintenance of ground networks The UAVs
were used in the countryside hilly zones whereas the communication was
inadequate The author anticipated resolving the viable communication difficulty in
5G and B5G vehicular ad-hoc The associate communication pattern established on
the smart UAVs was planned given the crisis condition of the car ad-hoc The smart
UAVs were supporting the vehicular ad-hoc strong communication in real
situations Above and beyond its actual characteristics of the vehicular ad-hoc were
needed to be endangered to avoid the prohibited features from attaining and
exhausting for law-breaking practices Innovative UAV with a secret authentication
key arrangement was recommended in the 5G and B5G vehicular ad-hoc Because
of supporting efficiency the vehicle network which guaranteed communication
confidentiality was not negotiated The suggested pattern was confirmed to be
unaffected by numerous outbreaks by exploiting the broadly applied natural or
random ROR scheme
Furthermore the projected scheme had well calibrated the communication
overhead from the performance estimation (J Zhang et al 2020) The UANs had
obtained a phenomenal role in the research area the emergent sector of aerial
robotics The parcel transport organization monitoring occurrence shooting
surveillance and tracing were the metropolises general operations utilizing the
UAV Various domains would use 5G and B5G to improve UAV networks UAV
ecological unit was advantageous in present 5G and B5G mobile communications
For UAVs intrinsic features they were concerned for flexible movement of three-
25
dimensional space independent actions and smart locations These devices were
provided with extensive scope in cellular networks The author proposed an in-
depth assessment of implementing cooperation between UAV and 5G and B5G In
which UAV had been assimilated as a novel user equipment of aerial in present
mobile communications The UAV had implemented the duty of flying users within
the network coverage named the cellular-connected UAVs in this amalgamation
The author showed a broad examination of the incorporation tasks with 5G and
B5G novelties Continued efforts in the prototyping and validation of mobile
communication UAVs were conducted using the ground trial The paper had
focused on the current growth in 3GPP The social-economic had not been taken
into account which was considered disadvantageous (Mishra amp Natalizio 2020)
The UAV was anticipated as the significant constituent in the 5G and B5G wireless
networks 5G enables the UAV to be used in broadcasting and end-to-end
communications using the small UAV They needed a devoted and endangered
aerial spectrum in the aircraft cargo by letting small UAVs run in space in
supervisory authority The security information was obtained from the link Control
and Non-Payload Communications (CNPC) The security information contained
the regulation of UAV and the line of sight of terrestrial The CNPC application in
the 5G and satellite communication was scrutinized in this paper Payload
communication like mm-Wave networks and UAV were analyzed in this paper The
direction-finding and reconnaissance difficulties were examined UAV
communication systems were scrutinized and the hardware challenges were
discussed (Hosseini et al 2019)
The potential gain from the UAV-assisted data gathering was found in
indiscriminate IoTs The characteristic propagation was represented by utilizing the
complicated channel method (contained small- and large-scale fading) IoTs were
updated in constrain of transmit power (in high) and total energy The multi-antenna
UAV was selected in the IoTs in sequence The virtual MIMO was created by the
communication between UAV and singe antenna IoT in every transmission (W
Feng et al 2018)
The UAV was applied in the aerial coverage surveillance agricultural prediction
constructional areas and power line supervising and blood donation The flight
26
period increment payload capability fast movement and speedy placements were
implied features in the UAV so that the UAV was exploited by the applications of
5G and B5G (Ullah et al 2020)
The UAV was considered a motivation for many emergent usages and reformed
social-economic welfares The wireless networks for the UAV and the base stations
were desired for the UAV function Mobile communications were considered
suitable for finding tracing and regulating the flying UAV The wireless
communications were selected for their features of broad coverage quality of
service and secrecy The wireless communication in the UAV improved
productivity besides the line of sight (G Yang et al 2018)
22 UAV-NOMA in Physical Layer Security enhancement
The NOMA has been applied in the fifth generation (5G) technology The Multicast
Cognitive Radio (MCR) network is implemented using the NOMA and coined as
MCR- MOMA The transmission side is also included with the superimposition
code The decoding was applied at the receiving end So an unknown user is
deduced in their methodology (Meng et al 2020)
The physical layer security for the cooperative NOMA was examined Amplify
and forward decode and forward were taken into consideration for achieving
secure transmission (Chen et al 2018)
The physical layer security of the NOMA was analyzed in the broader network with
varying locality The single and multi-antenna were established in the following
cases The single antenna was taken for an end-to-end connection in a secured
manner And the multi-antenna was used for the connection of base station and
random user Finally achieved security for the multi-antenna on the transmission
side The security of the single antenna was attained by introducing the excluding
area for eliminating eavesdroppers The individual expression of security outage
probability for both single antenna and multi-antenna were derived (Yuanwei Liu
et al 2017)
The secure transmission of NOMA in large-scale applications was investigated
Stochastic Geometry was utilized for placing the eavesdropper and user nodes The
equation for secrecy outage probability was derived and expressed for evaluating
27
secure transmission Security can be improved by expanding the protected zone
(Qin et al 2016)
The power domain NOMA had the disadvantage of decoding data by other
unauthentic users of the same source For reducing unauthentic users the base
station should treat the unauthentic users with different cleaning methods The
secrecy outage probability was investigated for authentic users and unauthentic
users Both users were combined as a pair to the non-uniform distribution of original
and unauthentic users The pair outage probability of genuine users from the secrecy
outage probability restrained NOMA authentic users The derivation for pair outage
probability and the secrecy probability were expressed for calibration The
combined system had been the better security (ElHalawany amp Wu 2018)
The physical layer security was considered problematic in the wireless networks
mainly for keeping the authentic userrsquos data The UAV was acted as the base
station UAV based base station had sent the extensive data to the original users
NOMA with the multi-antenna with mm-Wave frequency band transmission had
enhanced the spectral efficiency The physical layer security was attained by
announcing the space around user locality as the eavesdroppers protected zone
Covering the entire eavesdropper area was considered a resource-consuming way
The shape optimization for the protected location in each UAV base stations
altitudes was introduced The derivations for the secrecy sum rate and the secrecy
outage probability were expressed (Rupasinghe et al 2018)
The vehicular communication system had used cooperative NOMA The secrecy
outage probability was considered in vehicular communication The relay can be
used in both modes (half-duplex and full-duplex) in vehicular communication The
closed derivation for the secrecy outage probability was expressed The security of
the full-duplex NOMA resulted better than that of the half-duplex NOMA The
limitations are that the velocity of the vehicles was not considered Figure 21 is
illustrated the conceptual model of the vehicular communication NOMA system
(Xie et al 2019)
28
Figure 21 Vehicular communication NOMA system
The physical layer security of the uplink NOMA of the large-scale devices was
examined The connection networks had investigated with the approach called
stochastic geometry The new derivation was expressed for the coverage
probability The protected zone restrains eavesdroppers to the authentic users
Efficiency secrecy throughput was examined wiretap channels and the many
original users Constant transmission and variable transmission were collectively
inspected The signal to noise and the movement to interference ratio were derived
drastically (Gomez et al 2017)
The wireless system was executed using Space-Time Block Coding (STBC)
approach in the NOMA of mm-Wave MIMO The technique focused on haphazard
users So the pairing method was introduced mainly for Random Near-Random Far
(RNRF) Here the latent period could be minimized and the RNRF has also been
deduced for the overhead issue The result revealed the systems efficiency with a
proper implementation (Ghavidel et al 2020)
The recent arbitrary beam forming method was proposed in the multiple access
NOMA The pairing had decided to the user places So the evaluation was focused
on the system overhead The result revealed that the proposed work outperformed
29
the existing methods (Aghdam et al 2020) NOMA enhances the reliability of
multi-users transmission The sum rate could be reduced for improving Quality of
Service (QoS) power transmission and signal outage probability The
eavesdropper easily accessed the multi-access systems that cause physical security
during transmission (Z Li et al 2020)
The NOMA had provided spectral efficiency speed transmission of data multiple
networking and less latent period The NOMA utilizes the power domains for
various access Cognitive Radio Networks (CRN) is used to screen illegitimate
users The legitimate users were only permitted in the CRN by the Primary User
Networks (PUN) QoS The cooperative NOMA here implemented with the PUN
and the system performance is enhanced The spectral efficiency can be improved
by the secured transmission The cooperative NOMA was additionally developed
in the CRN with the PLS A new method of cooperative NOMA in the CRN was
examined The PUN technique attains a secure transmission Multiple antennae
were used in this study for reliability and the eavesdropperndashexclusion zone method
is used for better security (B Li et al 2018)
The downlink NOMA for moderate CSI was examined The challenge of the power
domain was rectified by allocating power NOMA The power in NOMA and that
of the OMA was analyzed which resulted in a significantly reduced NOMA (Cui
et al 2016)
Here the users were multiplexed by the power domain So the method was coined
as power domain NOMA The demand arising from the B5G (Beyond 5
Generation) had reached using power domain NOMA Machine learning in the
NOMA was described (Maraqa et al 2020)
The uplink NOMA with the PLS was proposed The uplink NOMA contained a
single base station and multi-users a couple of users combined for NOMA The
known jammer emitted the pseudo-noise to divert the eavesdroppers The study had
suggested the two jammers in the uplink NOMA for secure transmission (N Zhao
et al 2020)
The Intelligent Reflecting Surface (IRS) is designed using downlink NOMA The
multi-access had used the space direction of the beams of closure users The IRS
30
had performed the multi-access for every spatial order by the cell edge users of the
orthogonal beams (Ding amp Poor 2020)
The multi-input single-output NOMA has introduced the technique called Secrecy
Beam Forming (SBF) SBF had utilized the artificial noise for NOMA security
aided users in which the eavesdropperrsquos channels deteriorated The SBFs secure
transmission can be achieved in which high successive interference cancellation is
gained (L Lv et al 2018)
The superposition coding was performed in the transmission pat The successive
interference cancellation was conducted in the receiving position These two
techniques were combined in the novel 5G aided NOMA The basic concepts of
uplink and downlink NOMA were mentioned The dominant condition was
performed in the two user clusters of NOMA The prevailing state had issued the
confirmed spectral efficiency gain in NOMA (Tabassum et al 2016)
The relay scheme in IoT was examined for the secrecy of NOMA This was coined
as relay selection NOMA The base station had transmitted the secret messages to
the two NOMA-aided sensors and eavesdroppers IoT had treated the sensors and
eavesdroppers with different power allocations The expression for certain outage
probability and the strictly positive secure capacity was derived Increasing the
number of the relay would enhance the security in the NOMA-aided IoT The
outage probability for NOMA and OMA were compared The NOMA resulted in
better outage probability in Decode and forward mode (Do et al 2019)
31
Figure 22 RS-NOMA against an external eavesdropper
The NOMA-aided IoT was utilized to fight against the external eavesdropper as
Figure 22 The secured NOMA was proposed The base station sent secret
messages to several authentic destinationsmdashseveral eavesdroppers and unauthentic
users
Nakagami-m fading model was carried out using the multiple antennae in the
channel The security was attained using the max-min transmit antenna selection
scheme Both authentic and unauthentic eavesdroppers were analyzed The closed
derivation for the cumulative distribution of the original user was expressed first
That was compared with the unauthentic user The derivation for the secrecy outage
probability was obtained to identify the level of secrecy performance (Lei et al
2018)
Reconfigurable intelligent surface (RIS) aided NOMA was established for the
secrecy performance The main disadvantage of this model was the chance of using
RIS by the eavesdropper The secret outage probability was derived in this paper
The RIS improved the secrecy of the traditional NOMA The eavesdroppers were
limited from receiving the RIS signal by enhancing the number of intelligent
elements in the RIS A high signal-to-noise ratio was obtained from this experiment
(Liang Yang amp Yuan 2020)
32
The cooperative relaying NOMA was proposed for improving private transmission
in wireless networks Full duplex mode transmitted the jamming signals That
received the required communication at first Secondly the jamming signal
emission was sent by the base station The power allocation for the jamming signal
and information signal was decided on the eavesdropper channel state information
The eavesdropper was jammed by the signal from the first phase with maximum
power Second the derivation of the secrecy outage probability was expressed by
static eavesdropper CSI (Y Cao et al 2020)
The NOMA achieved spectral efficiency and secrecy The security of the multi-
NOMA users was obtained by the successive interference cancellation (SIC)
decoding in the receiving node The conservation of the untrusted NOMA was
concentrated in this study The security can be confirmed by the properly secured
decode processing and allocating power The decoding scheme was implemented
for aiding NOMA users The decoding was performed for enhancing the sum-rate
(Thapar et al 2020) The cognitive radio network in NOMA with the external
eavesdropper was proposed (Mehr et al 2020)
The cooperative NOMA was used in the field of energy harvesting communication
The novel relaying technique was introduced for achieving secrecy The secrecy
outage probability was derived and the derivation was expressed for the three
conditions The first condition was the derivation of CSI with a passive
eavesdropper The second condition was the derivation of CSI with the unauthentic
eavesdropper The third condition was the derivation obtained from the multi-relay
nodes The increased SNR resulted in high security The increase in the number of
users deduced security This was considered a disadvantage (Salem et al 2020)
Satellite communication covered more range of broadcasting So the security
challenge was considered a big difficulty in satellite communication Downlink
NOMA was assessed with an eavesdropper for the examination of secrecy The
paper concentrated on the physical layer security of downlink satellites Here two
methods were proposed The frequency-domain NOMA was considered for gaining
spectral efficiency The multiple user interferences were obtained in the process of
overlapping Introducing a suitable technique can be performed the security for the
number of users The secrecy rate was analyzed for all authentic users (and the
33
eavesdropper) and expressed in the derivation The safety was improved using the
spectral overlap method (Yin et al 2019)
The NOMA was considered as the emerging scheme in the upcoming wireless
networks The secrecy sum rate for the downlink NOMA (with MIMO multiple
inputs multiple outputs) was examined Downlink NOMA had the base station
number of users and the eavesdropper In the limitation of transmit power and
optimal successive interference cancellation the security was expected to enhance
Downlink MIMO NOMA was considered advantageous because of its secrecy
performance and the practical usage of bandwidth The mutual information rate and
the mean square error were causing the secrecy rate optimization to the problem of
biconvex This was rectified through the alternative optimization method and the
second-order cone programming was solved (Tian et al 2017)
Table 21 Comparative analysis
The comparative analysis for the physical layer security was examined in existing
studies
SR
No
Details of Author wise Contribution to NOMA Technology
1 Author (YFeng Yang amp Yan 2017) Secrecy performance in NOMA was
conducted with the help of artificial noise in the full-duplex mode of relaying
Methodology The optimization of the power was calibrated for the source
information and the noise signal The closed derivation for the secrecy outage
probability was expressed
Usage and limitations The physical security was increased
34
2 Author (He Liu Yang amp Lau 2017) NOMA was developed in the constrain
of security
Methodology The secret message had been sent to some users and also to the
eavesdropper The Novel decoding process was conducted for excluding the
unauthentic users The iterative algorithm was used for power optimization
Usage and limitations Transmit power was reduced The quality of service
was availed
3 Author (D Wang et al 2020) The secrecy was performed in the NOMA
The security was developed against the eavesdropper outside
Methodology The channel state information was analyzed for secrecy The
quantization of CSI had performed for secrecy The derivation for the secrecy
and transmission outage probabilities were obtained
Usage and limitations The secrecy rate was enhanced
4 Author (L Lv et al 2020) The physical security of the NOMA was
improved by adding artificial noise jammer and inter-user interference The
mode of full-duplex in the updated version was used in the NOMA
Methodology The eavesdropper can be trapped the superimposed signal from
the source So the secrecy was affected
Usage and limitations The spectrum usage is effective in the NOMA
transmission scheme Numerous connections can be performed in the NOMA
NOMA is considered to be the most advantageous for the upcoming
generation communications The superimposition technique was followed
4 Author (Yue et al 2020) Secrecy performance of the NOMA was developed
with a unique framework
Methodology The eavesdroppers inside the zone and outside the coverage
zone were examined properly in this paper The outage probability for codendash
power domain NOMA was derived
Usage and limitations Safety was acquired for both internal eavesdropper
and external eavesdropper in this scheme
35
5 Author (Guezouli et al 2020) The heterogeneous sensor network of cellular
communication was taken into account
Methodology Unmanned aerial vehicles are utilized the heterogeneous
sensor network of cellular communication
Usage and limitations Extended the life span of the network system The
cost of the hardware components is drastically low The random and the
repeats in the speedy movement The latency is maximized The coverage
period is maximum
6 Author (Yao amp Xu 2019) The security in transmitting a large amount of
information in the wireless network systems are analyzed with unmanned
aerial vehicle UAV
Methodology The numbers of UAVs are arranged in the space The base
station sent the information to the UAV in the space The authentic receivers
have obtained the secured information from the UAV The HPPP
homogeneous Poisson point process is used for distributing the authentic
receiver and eavesdropper in the line of sight
Usage and limitations The increase in the number of safety zone causing the
secured transmission
7 Author (Saacutenchez et al 2020) Physical security can be achieved by the
method of a unique encryption scheme
Methodology The physical layer security of the following schemes is
discussed in this paper mm-wave NOMA massive multi-input multi-output
heterogeneous sensor networks full-duplex mode
Usage and limitations The physical layer security was analyzed for the 5G
supporting technologies Good reliability achieved The less latent obtained
Machine-type communications can be enabled
36
8 Author (Hou et al 2018) The multi-antennas were used in NOMA with
UAV The stochastic geometric approach was examined
Methodology The multi-input multi-output kind of NOMA was utilized In
common the stochastic geometric approach was used for drastically moving
NOMA
Usage and limitations The maximum signal-to-noise ratio was obtained in
this scheme Power optimization was achieved The path loss is less Good
spectral efficiency was obtained
9 Author (Miao et al 2020) The broadcast type of communication was
performed The less weighed three-dimensional space for 5G communication
was analyzed
Methodology Both the performances of multicast and broadcast were
enabled UAV-assisted 5G communication systems are emerging in the
upcoming wireless networks
Usage and limitations Better flexibility in the network Continuous mobility
One lined line of sight
10 Author (Majhi amp Mitra 2020) The secure communication in cognitive radio
by NOMA was propounded
Methodology The antenna strategy of giving minimum outage probability
was concluded from this study
Usage and limitations The limitation is that more spectral efficiency causes
security issues
11 Author (X Zhao amp Sun 2020) Secure communication of the physical layer
in Visible light NOMA Communication was proposed
Methodology Energy optimization in security constrain was propounded for
achieving overall performance
Usage and limitations It is difficult to find optimal results because energy
optimization is the nonconvex issue
37
12 Author (Tuan amp Hong 2020) Secure communication in simultaneous
wireless information and power transfer NOMA was remitted
Methodology Eavesdropper is used for security purposes between the user
and base station using energy relays Known jammer is used for secure
transmission For energy efficiency storing and transferring were propounded
Usage and limitations Jamming requires extra power allocation
13 Author (Vaezi et al 2019) NOMA for 5G in mmWave MIMO cooperative
and cognitive were analyzed in this study
Methodology SWIFT NOMA is useful for weak receivers
MIMO using more antenna
Usage and limitations multi-antenna utilization cause high power
consumption
14 Author (Vaezi et al 2019) Mobile edge computing NOMA was proposed to
optimize power
Methodology Minimum latency and less power consumption
Usage and limitations Transfer power allocation must be calibrated
15 Author (Faraji-Biregani amp Fotohi 2020) Security in UAV communication
was proposed by introducing mobile agents
Methodology Malicious user of UAV was identified
Usage and limitations Three-phase power is essential
16 Author (G Zhang et al 2019) Secure communication in 5G UAV was
propounded by joint trajectory carrying out in physical layer
Methodology Power optimization was proposed for security
Usage and limitations Security in the physical layer was achieved by
optimization of trajectory
17 Author (Fotohi et al 2020) Agent-based self-protection was propounded in
UAN for secure communication
Methodology This method imitates the immune system of human beings
Less cost
Usage and limitations Energy is not optimized properly This approach
needs to consider other malicious attackers
38
18 Author (Shang Liu Ma amp Fan 2019) Vehicle to everything approach was
propounded for security in a UAV
Methodology Security of vehicle to the vehicle was proposed by considering
eavesdroppers active and passive attacks
Usage and limitations High price
19 Author (Kantor et al 2017) The flight path was calibrated in a UAV
Methodology Security performance was achieved by encryption as well as
anonymization
Usage and limitations High in cost and hardware structure occupies more
place
23 Research Methodology
The NOMA-based cellular architecture for UAV communication has been
considered here as reference network architecture Rayleigh fading has been
assumed as a channel characteristic The performance parameters for PHY layer
security are (1) Pair Outage probability (Pair OP) between two users trusted near
user designated as U1 and untrusted far user designated as U2) and (02) Secrecy
Outage Probability (SOP) of trusted near user designated as U1 The aim is to
achieve optimal Pair OP for the given constrained SOP of User U1 so that network
resources can be efficiently allocated to both users without compromising the
secrecy of trusted User U1
The mathematical analysis from reference literature (ElHalawany et al 2018) has
verified and supported the joint optimization of the Pair OP and SOP for the given
power allocation factor in NOMA This research work is extended as providing
more efficient resource allocation using the POMDP algorithm in a given scenario
First the varying distance of untrusted user U2 from BS as a critical selection
parameter that affects Pair OP amp SOP of user U1 and U2 both has been simulated
and the feasible and infeasible pairing of both users have been analyzed The
optimal power allocation factor for feasible pairing as the constrained problem is
optimized by opting for POMDP as a resource allocation algorithm wherein the
SOP of user U1 is strictly maintained for given CSI POMDP provides optimum
39
power allocation factor for trusted and untrusted users pairing as shown in the
proposed flow of POMDP algorithm is used to model a variety of real-world
sequential decision-making problems After the BS has been set up the distance
between the BS and the user is calculated and if space is less than 200m it is
defined as a trusted user While if the range is more than 200m it is described as
untrusted users In the case of trusted users the channel state information (CSI) is
provided to the proposed algorithm POMDP for reliable and efficient resource
allocation
24 Summary
UAVs play a central role in providing network service recovery in a disaster-
stricken region enhancing public safety networks or handling other emergencies
when Ultra-Reliable Low-Latency Communication is required In particular UAV-
assisted communication can be regarded as an important complement to the 5G
cellular networks Surveyed literature related to UAV communications published
over the past several years emphasized the cybersecurity and channel modeling for
UAV communications etc Security is one of the critical issues in communications
Modern communication networks are based on the layered architecture from the
physical layer up to the application layer A great deal of effort has been made to
develop the cryptographic protocols above the physical layer However the
physical layer is not as robust as that in wired communications The physical layer
in wireless communication is more complex than the counterpart in other
communication paradigms The concerns come from not only the noises but also
many types of fading Recently there has been an influential interest in studying
the security issues in the physical layer Security is highlighted as another
challenge and the implementation of physical layer security techniques is seen as
a difficult task PHY security in NOMA systems under the presence of external
eavesdroppers or untrusted relay nodes Upcoming 5G networks for unpredicted or
crisis (disaster management) the placement of terrestrial substructures is
economically infeasible and challenging due to high operational expenditure as well
as sophisticated and volatile environments
To address such novel issues intelligent heterogeneous architecture by leverage
UAV has been well-thought-out to be a promising novel model For advancing the
40
performance of the UAV 5G communication system physical layer techniques are
of many effects as they have impacted the applications of UAVs Security of
NOMA-based UAV communication network has been scrutinized for optimization
as physical layer security
41
CHAPTER-3
SYSTEM MODEL FOR NOMA-UAV
COMMUNICATION
31 NOMA-UAV System Secured Communication for 5G
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
311 The basic scheme of NOMA
The NOMA system allowed several users to be served simultaneously by the
transmitter To transfer a linear combination of different signals towards the
recipient the system of proportional representation superposition coding (SC) The
transformed signal is provided through
σ ඥ119875119896 119878119896119870119896 =1 -------------------------------------- (1)
Where 119927119948 represents the transmit power assigned toward user k th
119930119948 indicates the normalized message used for user k th
42
The instantaneous total converses power is σ 119927119948119922119948=1 The received signal at user kth
and the eavesdropper are offered through
119910119896 = ℎ119896 σ ඥ119875119896 119878119896119870119896=1 + 119899119896 -------------------------- (2)
119910119890 = ℎ119890 σ ඥ119875119896 119878119896119870119896=1 + 119899119890 -------------------------- (3)
Where 119951119948 and 119951119942 indicated the zero-mean Additive White Gaussian Noise
(AWGN) at user k th with variance 1205901198962 and the zero mean AWGN at eavesdropper
with variance 1206481199422 respectively We assume that the noise variances at all the users
are identical
ie 12059012 = ⋯ = 120590119896
2 = 1205901198902
As per NOMAs process the SIC is followed by all users to decrypt the message to
the same decoding order Notice that it is not known what the optimal decoding
order is for the NOMA method that corresponds to secrecy
Therefore the mth message to be encoded to the user might not be the mth message
to the user As such we also have to add the π variable For example if 120587(1) =
3 then the first message to be decoded for the SIC is the message for the user 120645(119947)
forall j lt k before decoding its letter to remove the inter-user interference successively
Then the user 120645(119948) denotes its message while treating the news for all the user
120645(119946)foralli gt k as the interferences The received Signal-to-interference-plus ndashnoise
ratio (SINRs) at user 120587(119896) k lt K and user 120587(119870) to decode their messages are
respectively given by
119878119868119873119877120587119896=
120574120587(119896)119875120587(119896)
1+120574120587(119896) σ 119875120587(119894)119896119894=119896+1
119896 lt 119870 --------------------(4)
119878119868119873119877120587119870= 120574120587(119870)119875120587(119870) --------------------------------------(5)
Were 120574120587(119896) =หℎ120587(119896)ห
2
1205901199062
൘
43
Also the acknowledged SINR at user 120587(119898) to decrypt the message 120633120645(119948) 119896 lt
119898 le 119870 is given by
119878119868119873119877120587119896=
120574120587(119898)119875120587(119896)
1+120574120587(119898) σ 119875120587(119894)119896119894=119896+1
kltmle 119870 --------------(6)
Similarly the acknowledged SINRs by the eavesdropper of the message 120575119896 119896 lt
119870 and the message 120575119896 are respectively given by
119878119868119873119877120587macr
119896=
120574119890119875120587(119896)
1+120574119890 σ 119875120587(119894)119896119894=119896+1
klt119870 ----------------- ------(7)
119878119868119873119877120587macr
119896=
ȁℎ119890ȁ2119875120587(119896)
1205901198902 = 120574119890119875120587(119896) klt119870 ---------------------(8)
Where 120574119890=ȁℎ119890ȁ2
1205901198902൘
Notice that here expressions for the obtained SINRs at eavesdropper overestimate
the skill of eavesdropper Here a worst-case inference from the viewpoint of
legitimate users is made That is the messages have already been decrypted by the
eavesdropper for all users π (j) forall j lt k before attempting to decrypt the message
for the user π (k)
The presumption also assumes that the decrypting order and power distribution are
understood by the eavesdropper The eavesdropper may or may not recognize the
decoding order of the users and the allocation of power may or may not recognize
the messages for all users π (j) forall j lt k before attempting to decode messages for
users π (k) However since the eavesdropper has been unable to alert the authorized
customers of its capacity and the current CSI the approved user would be unable
to know the eavesdroppers details Therefore we have to pursue the worst-case
scenario for the permissible users point of view due to the liberality required by the
safety reports It highlights that the worst-case assumption in the study and design
of transmission schemes with secrecy requirements has been generally adopted
The proposed study has been evaluated using performance measures Here we
analyze NOMA with downlink and uplink networks suggested by SINR and Sum
44
Rate survey High SNR is then simulated to contrast the OMA and NOMA
processes
312 Downlink of NOMA
The Downlink of the NOMA network on the transmitter side is described in Figure
31 SIC method is supposed to be carried out successively on the receiver side of
each user until another signal is restored The coefficients of users are owed in an
inversely proportional manner based on their available bandwidth
Figure 31 Downlink NOMA network
A consumer with a poor available bandwidth has a transmission capacity of a
higher range than a consumer with strong available bandwidth As a consequence
the consumer with the higher power assumes the signals of other users to be noisy
and automatically restores the signal without conducting any SIC operation The
receiver of each consumer detects indications that are stronger than those of the
desired signal These impulses are then deducted from the power and this process
continues until the signal has been calculated Both users decrypt their signaling by
considering other users with lower correlations The signal is calculated as
45
119904 = σ 119886119894119875119904119883119894119871119894=1 -----------------------------------------------(1)
Where Xi is the user ithrsquos information through unit energy
Ps is the capacity of transmission at the BS
ti is the coefficient of power assigned for user i
Although without the need for lack of generality the channel profits are expected
to be graded as ȁℎ1ȁ2 le ȁℎ2ȁ2 le ⋯ ȁℎ119871ȁ2
Where 119945119923 is the coefficient of the channel of the user Lth
The received signal of the Lth user is calculated as
1199101 = ℎ119897119904 + 119899119897 = ℎ119897 σ ξ119886119894119875119904119883119894119871119894=1 + 119899119897 -----------------------------(2)
Where n1 is zero mean Complex Gaussian noise with a variance of 1206482SINR
analysis with the equation (2) the SNR of Lth user to identify the user 119895 le 1with
119895 ne 1
119878119868119873119877119871 = 1198861120574 ȁℎ1ȁ2120574ȁℎ1ȁ2൘ σ 119886119894 + 1119871
119894=119871+1 ------------------------(3)
Where 120632 = 1198751199041205902ൗ represents the SNR
Sum rate analysis After identifying the SINR of the downlink the sum rate will
also be done quickly
The NOMAs downlink data rate of Lth user can be calculated as
1198771119873119874119872119860minus119889 = 1198971199001198922(1 + 119878119868119873119877119871) --------------------(4)
313 Uplink of NOMA
The Uplink NOMA is depicted in Figure 32 where each user sends a signal to the
BS SIC iterations are supported to classify the signals of mobile users If both
channels are identical and BS sends the coefficients of power allocation to mobile
users the received signal can be interpreted as a synchronous uplink to the NOMA
46
119955 = σ ℎ119894ඥ119886119894119875119909119894119871119894=1 +n ----------------------------------(5)
Where hi is the coefficient of the channel for the ith user
119927119961119946 is the extreme transmission capacity supposed to be general to all users
N is zero-mean Gaussian noise with a variance of 1206482
Figure 32 Uplink NOMA
Analysis of SINR The BS decrypts the signals of the users as per the coefficients
of the users and the SINR for the Lth user can be defined as
119878119868119873119877119871 = 119886119897120574ȁℎ119897ȁ2120574 σ 119886119894ȁℎ119894ȁ2 + 1119897minus1
119894=1൘ ----------------------------(6)
Where 120574 = 1198751205902ൗ indicates SNR
Analysis of Sum rate The sum rate of uplink NOMA when 120632 minus infin can be
computed as
119877119904119906119898119873119874119872119860minus119906 asymp 1198971199001198922(120574 σ ȁℎ119897ȁ119871
119894=1 2 ------------------------ (7)
47
314 Comparison of NOMA and OMA
The attainable data rate of the Lth user of OMA intended for both uplink as well as
the downlink is estimated as
119877119904119906119898119874119872119860 = σ 120572 1198971199001198922120574(1 +
120573119897ȁℎ119897ȁ2
120572119897119871119894=1 ) --------------------------(8)
Just for convenience two users should evaluate the summation of uplink rates for
NOMA and OMA The use of both the uplink rate of NOMA and OMA at high
SNR can be calculated as---
119877119904119906119898119873119874119872119860 asymp 1198971199001198922(120574 ȁℎ1ȁ2 + 120574ȁℎ2ȁ2 ------------------------- (9)
equation (7) and (8) it is seen that 119877119904119906119898119874119872119860 le 119877119904119906119898
119873119874119872119860
Here we note 119929119956119958119950119926119924119912 le 119929119956119958119950
119925119926119924119912 shows that NOMA performed better than OMA in
terms of sum rate in both downlinks as well as uplink of two user networks
The sum rate will be calculated after the SNR as the formulation is shown In this
proposed work multiple users are propagated to the process of NOMA and here a
comparison of NOMA as well OMA has been defined The NOMA uplink and
downlink using the OFDMA method for the
32 PLS performance metrics in NOMA -UAV communication
This chapter mainly describes the proposed work to examine the availability of the
outage probability of the pair below an authorized user According to the decryption
of SIC availability and spectrum sharing the unauthorized user can function as an
eavesdropper and obtain an outage probability (OP) for all situations with the
Secrecy Outage Probability (SOP)
321 SOP and OP - two user and multi-user NOMA system
NOMA system has the capability for assigning multiple data over the transmission
signal through high-level coding (Shim amp An 2018) Thus it contains spectrum
efficiency when opposed to OMA But this has a limitation in security As an
48
instance if the eavesdropper is reached then it obtains multiple user data in the
interference of the NOMA signal Thus the security issues are more significant in
this system Here PLS is an available method to rectify the attack intended for
malicious users (Dai et al 2015)
Additionally data should be transmitted confidentially if the root and eavesdropper
networks can be evaluated and the recipient can decrypt the received text At the
same time the eavesdropper is not able to solve the text that has been interrupted
PLS is at the cutting edge of wireless communication security technology to prevent
eavesdropping attacks The SOP is described as the likelihood that the near users
attainable device confidentiality capability will fall under the predefined target
confidentiality rate as set out in (Shim et al 2017)
Through SOP we can calculate the level of protection of the device As an example
the low-secret OP system makes the system more stable in terms of security than
the high SOP system To boost the efficiency of the PLS CSI-based opportunistic
scheduling links to a scheduled destination in a particular time slot It has been
documented as an enticing scheduling scheme (Long Yang et al 2016) because the
various wireless channel has been exploited Opportunistic scheduling is also
considered to be one of the strategies used to increase the confidentiality efficiency
of the NOMA method
322 System Model
Suppose a multi-user NOMA system of downlink containing BS a selection of K
nearer users as N= 119873119894ȁ12 119870 and a range of M far users as F=
119865119895ȁ12 119872 and an eavesdropper E as displayed in Figure 33 More
specifically nearer users should make active use of the SIC methodology to
distinguish far user F Both the legitimate and illegitimate receivers are furnished
through a single antenna and operate in a half-duplex manner
49
Figure 33 Multi-two user architecture of NOMA system (Shim amp An 2018)
Here 119945119935119936 and ȁ119945119935119936ȁ2
Where X120598ሼ119878ሽ 119884120598119873 cup ሼ119864ሽ represent the channel coefficient and the corresponding
channel gain of the X-Y value
Taking into consideration that each wireless channel for Rayleigh block fading 119945119935119936
can be incorporated as an independently distributed random Gaussian variable with
zero mean and affirmative ℷ119935119936 Variance The outcome of channel gain ȁ119945119935119936ȁ2is an
exponential variable randomly through the Probability Density Function (PDF)
119891ȁℎ119883119884ȁ2(119911) = ቀ1
ℷ119883119884ൗ ቁ 119890119909119901 (minus 119911
ℷ119883119884ൗ )
if zge 0 119900119905ℎ119890119903119908119894119904119890119891ȁℎ119883119884ȁ2(119911) = 0 -----------------(1)
Especially the average channel profit can be represented as
ℷ119883119884= ൬119889119883119884
1198890൘ ൰
minus휀
ℒ ------------------(2)
When 120027 is the attenuation of the received signal 119941119935119936 signifies the distance among
X and Y 1199410 indicates the space and 120656 is the exponent of the path loss It is believed
that the source is entirely familiar with the CSI of both legitimate users and
eavesdroppers
50
323 Partially Observable Markov Decision Process-POMDP
Figure 34 Flow Diagram of the proposed system
The proposed overflow is shown in Figure 34 After the BS has been set up the
distance between the BS and the user is calculated and if space is less than 200m
it is defined as a trusted user While if the range is more than 200m it is described
as untrusted users In the event of untrusted users the channel state information is
accessible to the POMDP accompanied by the allocation of resources The study
was carried out after the machine operation Here a NOMA-oriented cellular setup
provided with a BS at the Centre and two users was described in Figure 35
51
Figure 35 Near and Far User
The adjacent user has a high level of security confirmation needed to protect the
layer since the low-security clearance user is situated at a distance away from the
BS P is specified as the highest level of transmitting power In this chapter it is
presumed that all DNS servers are furnished utilizing an individual antenna and all
channels are supposed to be individually static identical to the Rayleigh
dissemination concerning distribution
119862119873(0 120575119898
minus120572
212059601 2Τ
)
In which 120633119950 is the range between the BS and the nodes 119932119950 Here the path-loss
exponent and constant are defined as 120630 and 1206540 Furthermore BS is assumed to
have predicted the position of the user so that a better CSI can be obtained at BS
that is elaborate in user pairing
The BS transmits the superimposed mixture
119909119905 = ඥ1199051199041 + ඥ1 minus 1199051199042 ------------------------------- (3)
In which 1199561 and 1199562 are the unit of power signals received by users 1199321 and 1199322
respectively t is the power allocation coefficient for the adjacent user
1199031 = ℎ1119909119905ξ119875 + 1198991 ------------------------------- (4)
1199032 = ℎ2119909119905ξ119875 + 1198992 ----------------------------------(5)
Where 1199451119886119899119889 1199452 the channel profit link with the fading of small scale since the
BS to the user 1199321 and 1199322 respectively The additional Gaussian noise with variance
52
is denoted 1199511 119886119899119889 1199512 and zero mean 119894119904 119889119890119899119900119905119890119889119886119904 (1199250) and it is assumed
that the BS conveyed SNR is 120646 = 1199271199250
ൗ
In the NOMA technique additional users with more power may decode their signal
by recognizing the adjacent signal as noise without decoding the adjacent user
message In the previous equation 1198801 is supposed to first solve a weak signal by
decoding its own SIC signal1198802 which is an unauthenticated user attempted to
decrypt the nearer user text after decrypting the adjacent usage text after decoding
its own SIC message The following equation has therefore been achieved
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2 ----------------(6)
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2 ----------------(7)
119879119900119905119886119897119904119894119899119903 = 11987811986811987311987721 1198781198681198731198771
1 119878119868119873119877221198781198681198731198771
2 -----------------(8)
Where 119930119920119925119929119950119951
indicates the SINR ratio of user mth that was decoded by 119932119951 for
119898 119899 isin ሼ119894 2ሽ and the channels gain followed an exponential distribution with the
parameter 120649119950=120654120782120633119950minus120630
324 Problem formulation
As a result the BS could achieve and provide better communication for users who
are vulnerable to security threats from unauthenticated users the proposed
framework identified two kinds of QoS energy efficiency that could be considered
essential for addressing the problem In a particular study a pair of OPs was
specified to check the reliability at which the attainable data rate for users is equal
to or greater than the threshold of minimum reach The following issue aimed at
reducing the pair OP to an SOP factor intended for the user 119932120783 that is provided by
Where 1199270is Outage Probability- (OP)
1199271 is Secrecy Outage probability user U1 119930119926119927(119932120783) and
120631 the permissible SOP threshold
53
33 Performance Analysis Improving PLS Insecurity of NOMA
System
331 The Pair OP Calculation
Through Shannons capacity formula and assuming 119914120783119957119945 119886119899119889 119914120784
119957119945 as the
threshold capacities of users 119932120783 119886119899119889 119932120784 respectively the combination of OP
could be offered by
119927119954 = 120783 minus 119928120783119961119928120784 in which 120649119950 = 120784119940119950119957119945
119950 isin ሼ119946 120784ሽ -------------(9)
empty120783 =120649120784
120646(120783+119957+120649120784119957) empty120784 =120649120783
120646119957
119928120783 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ 120782 lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 ------------------------(10)
Case 1empty1 gt empty2 for having the limitation of the allocation of power factor (t)
required to be satisfied (tgt120649120783
120649120783+120649120784+120649120783120649120784) and for this case 119928120784 could be attained as
follows
119928120784 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ
120649120783
120649120783+120649120784+120649120783120649120784lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 --------------(11)
Case 2 empty1 lt empty2 Like case 1 it was stated that the opposite constraint depends
on
t gt 1206491
1206491+1206492+12064911206492 and 1199282 can be evaluated as follows
119928120784 = ൝119942119961119953 ቀ
minusempty120784
120649120783ቁ 120782 lt
120649120783
120649120783+120649120784+120649120783120649120784
120782 119952119957119945119942119955119960119946119956119942 ---------------------(12)
54
Table 31 List of parameters
Parameters Description
N Number of nearer users
M Number of far users
E Eavesdropper
ℎ119909119910 Channel coefficient between 119909119905ℎchannel and 119910119905ℎ users
119889119883119884 The distance among x and y
1198890 Space
120598 An exponent of the path loss
ℒ Attenuation of the received signal
120575119898 the range between the BS and the nodes
1205960 Path loss constant
120572 Path loss exponent
1199041 1199042 Unit of power signals received by users 1198801 and 1198802
T Power allocation factor for the adjacent user
ℎ1119886119899119889ℎ2 Channel coefficient of 1198801 and 1198802with the fading of small
scale
11989911198861198991198891198992 Gaussian noise variance
1198730 Zero mean for Gaussian noise
120588 Signal to noise ratio
119878119868119873119877119898119899
Signal to interference noise ratio of users n and m channels
55
120591119898 Exponential distribution parameters
1198750 Pair of OP
1198781198741198751 119878119874119875(1198801)
120573 The permissible SOP threshold
Table 31 depicts the list of parameters used in the proposed methodology which
are useful for assigning and the values are assigned based on the parameters given
for the experimental evaluation as well This chapter concludes with the basic and
the actual flow of the proposed method to know more about the work in the
simulation process
332 Pseudo-code for the proposed algorithm
Algorithm I
Step 1 Estimate Rayleigh distribution
119862119873(0 120575119898minus120572 2Τ
1205961199001 2Τ
) where
120633119950 is the distance between nodes 119932119950 and the BS
120630 is the path-loss exponent and
120654119952 is the path-loss constant
Step 2 The BS broadcasts the superimposed mixture and input signal as follows
119909119905 = ξ1199051199041 + ξ1 minus 1199051199042
Where 119956120783 and 119956120784 are the unit power signals received by users 119932120783 and 119932120784
respectively 119957 is the Power allocation coefficient for the near user
Step 3 The received signal is as follows
1199031 = ℎ1119909119905ξ119875 + 1198991
1199032 = ℎ2119909119905ξ119875 + 1198992 where
56
119945120783 and 119945120784 are the channel gain associated with the
small-scale fading from the BS to users 119932120783 and 119932120784 respectively
1199511 and 1199512 are the additive white Gaussian noise with zero mean and variance
119925120782
Step 4 the BS transmit signal-to-noise ratio (SNR)
120646 = 119927119925120782
Step 5 Signal-to-Interference-plus-Noise-Ratio (SINR) for the two users 119932120783
decodes the signal of the weak user first then decodes its own signal after using
SIC 119932120784 is an untrusted user and tries to decode the near user message after
decoding its own message using SIC
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588ൗ and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ2ȁ2+1120588ൗ and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2
119879119900119905119886119897119904119894119899119903 = ሼ11987811986811987311987721 1198781198681198731198771
1 11987811986811987311987722 1198781198681198731198771
2ሽ
where 119930119920119925119929119950119951
is the signal-to-interference-plus-noise-ratio (SINR)
of user 119950th decoded by 119932119951 for 119898 119899120598ሼ119894 2ሽ and ȁ119945119950ȁ2 is the
channels gain of 119932119950
Algorithm II
Partially observable Markov decision process
Step 1 Prediction of the maximum capacity of channel with respect to the data rate
119955119943 = 119877(119878119909119863)
S is denoted as states
Let D be the channel characteristics which are considering here as actions
Reward function R
Step 2 The agent receives an observation 119900120598120118which depends on the new state of
the environment 119930prime and on the just taken action 119941 with probability
119926(119952ȁ119956prime 119941)
Step 3 Reward earned at time t is expressed as
57
119903119891119905 = 119877(119878119909119863)119905
Step 4 reward function on belief states
119919 is the belief states over POMDP states
119919119943 is the belief state transition function
119955119943 = 119877(119867119909119863)
Step 5 The reward function is updated based on the belief MDP the agent only
cares about which action will yield the largest expected immediate reward ie the
maximum capacity channel
119861119891 ቀℎ 119889 ℎprimeቁ = 119875119903 (
119900120598120118
ℎprimeȁℎ 119889 119900) 119875119903(119900ȁ119889 ℎ) 119861119891
119875119903(ℎprimeȁℎ 119889 119900) = ቄ1119894119891119905ℎ119890119887119890119897119894119890119891119906119901119889119886119905119890119908119894119905ℎ119886119903119892119906119898119890119899119905119904ℎ 119889 119900119903119890119905119906119903119899119904ℎprime
0119900119905ℎ119890119903119908119894119904119890
119903119891(ℎ 119889) = σ ℎ(119904)119877(119904 119889)119904isin119878
34 SUMMARY
The NOMA-UAV communication framework has been proposed in this research
work and the Physical Layer security aspect has been focused on for optimization
The PLS performance metrics selected are SOP amp Pair OP in the proposed system
model The POMDP framework is general enough to model a variety of real-world
sequential decision-making problems Applications include robot navigation
problems machine maintenance and planning under uncertainty in general Here
we have adopted the User pairing POMDP algorithm for resource allocation in two
users amp multi-user NOMA-UAV communication networks The proposed study has
been evaluated using performance measures by varying distances of trusted amp
untrusted users from the base station as well as for varying SINR conditions The
simulation results and outcomes are discussed in a further chapter
58
CHAPTER 4
RESULT AND DISCUSSION
41 PERFORMANCE MEASURES OF SECURED NOMA-
UAV COMMUNICATION MODEL
Drones or UAV-based communication technology has been thoroughly studied and
adopted by the 3GPP standard UAV systems have been envisaged to form an
integral part of future wireless communication applications due to their dynamic
flexible and flying nature Due to their ability to reach higher altitudes they usually
have dominant LOS channels with the ground nodes This capability can be used to
provide confidentiality to the legitimate receivers against the eavesdroppers This
can be done by deploying UAVs to launch more effective jamming signal attacks
to terrestrial eavesdroppers The conventional cooperative jamming schemes make
an assumption that the locations of terrestrial jammers are fixed which might
compromise the secrecy of the system if the jammers are located far away from the
eavesdroppers and is also not practical as it makes an assumption of perfect CSI of
the jammer to eavesdropper channel
Here in the proposed scenario of the NOMA-UAV communication network two
key PHY layer security metrics SOP amp Pair Outage Probability have been jointly
optimized for a more effective power allocation factor for NOMA cellular
architecture The varying channel characteristics have been analyzed to achieve the
desired SOP with the constrained threshold minimum target secrecy rate for the
two-user scenario POMDP Algorithm iteratively provides the optimized SINR that
has been used to keep trusted users in pair with the untrusted user with minimum
achievable outage probability
The proposed NOMA-UAV System model has been simulated in MATLAB 2019b
version with mainly Communications System Toolbox Optimization Toolbox RF
Toolbox Signal Processing Toolbox Statistics and Machine Learning Toolbox
The simulation has been carried out for two-user pair to achieve desired secrecy
target rate and feasible pairing between trusted user amp untrusted user(eves-dropper)
59
The optimal-outage performance of minimized pair OP subjected to SOP constraint
has been solved by both dynamic programming optimization and POMDP
optimization approaches
The simulation of the proposed framework for the UAV-NOMA communication
network has been carried out and discussed in two parts two user models and a
multi-user model as below mentioned discussion The base station is deployed at
the center of a cell of radius 1000 m There are two users in the system under
consideration The channel between two nodes in the system suffers both the small-
scale fading and path loss effect Small-scale fading follows the exponential
distribution with the mean value 1 The noise signal of all channels has a Gaussian
distribution with 0 mean and variance 1 The path loss exponent α and the path loss
constant PLo are set to 2 and 01 respectively We assume a normalized bandwidth
of 1 Hz The SOP constraint threshold is assumed 01 and the target secrecy rate is
001 The power allocation coefficient is 015 and the BS transmitted SINR is
assumed 15dB for the proposed model As per the NOMA transmission scheme
SINR has been obtained for User 1 amp User 2 both for SIC decoding POMDP
algorithm optimally tunes the SINR value for User 1 amp User 2 that is considered to
select optimal power allocation coefficient for both trusted and untrusted users with
respective SOP of User1
42 Numerical results and Discussion
Table 41 Simulation Parameters
Parameters Values
Untrusted user Distance (d2) 200-1000 (300 700)
BS transmit signal-to-noise ratio (SNR) (120588) in dB 15
Sop constraint constant threshold (β) 01
Power allocation factor (t) 015
Trusted User distance (d1) 2-
60
Cell Radius (rd) 1000 meters
Path loss exponent (α) 2
Path loss constant (PLo) 01
Normalized bandwidth in Hz 1
Target secrecy rate (Rs) 001
No of Bits 100
Pair Outage Probability (P0) 05250
SINR 5319 15305 5162
10247
421 Feasible amp Infeasible pairing of trusted amp Untrusted users
In this section the CSI value broadcasted by Base Station is assumed 15 dB initially
and for varying channel conditions various SINR values of 120646 = minus20 minus10 20 dB
is described with target secrecy rate 0005 and 001 for power allocation coefficient
015 and User 1 distance at 200m is shown in the Figure 41 below
Figure 41 Impact on Sop with increase distance between BS and user U2
61
Varying target secrecy rate threshold from 0005 to 001 the obtained result in
Figure 42 revealed that the 1199321 is a gradually reducing function for the distance of
untrusted user d2 that implies that the increasing value of d2 leads to the
improvement of the SOP of 1198801
Figure42 Impact on Sop with increase distance between BS and user U2
Since the offered constant threshold 120656 in SOP limit1199322 which should be located at
a larger space when compared with a value of threshold to attain the SOP of 1199321
apart from that it is expected the high target secrecy rate maximizes the SOP of 1199321
Here in below figure the power allocation coefficient has been varied from 0 to 1
with threshold value of t and the desired t_sop for feasible pairing
Figure 43 Feasible pairing t Vs pair OP
62
Pair OP in case of rising 1199322 untrusted user in d2 for different BS transfer the SNR
where t= 015 and d1=200mThe infeasible pairing of SOP (1199321) and the OP pair
by the enhanced allocation of the power (t) d1 (200m) d2 (300m) 120646 = 15 dB and
120656 = 0
Figure 44 shows the identical plotting of data by adjusting the unauthenticated
level of the user through converting it to a BS closer distance (d2=300m) Accuracy
is compared and checked with the full spectrum of numerical simulations The
result has shown that the effectiveness is based on a comparative study of the two
consumers of the BS
Figure 44 Infeasible pairing t Vs pair OP
422 The Secrecy Outage Probability amp Pair Outage Probability
Feasible paring in the SOP of pair OP and 1199321 with the improved power allocation
factor t in which d2=700m d1=200m 120646 = 15119889119861 and The result described that
the OP and SOP of the user 1199321 with increased for two various distances of the 1199322
untrusted user The simulation result approves the convex nature 120656 = 0 1of the OP
and the SOP is sequentially decreased depending on t Generally when it enhances
the power owed to the weak user text reduces that develop the ability of 1198802 for
discerning the superior positioned signals therefore enhancing the SOP of 1198801
63
Figure 45 Secrecy outage probability
Figure 46 Pair outage probability
423 SNR versus Strictly Positive Secrecy Rate
Figure 47 proved that the potential for confidentiality is superior to the existing
techniques The proposed application for pre-coding improves the efficiency of the
device The transmission power of the system is the power needed for the
transmission of particular data
64
Figure 47 SNR versus Strictly positive secrecy rate
If there is a growth in the number of users there is a risk of inference in the
transmission of data and thus the reliability of the data rate may be affected Based
on these cases the efficiency of the antenna power to be withheld and occupy the
data determined
424 Power radiated by per MMBs antenna
In the case of multi-users scenario when there are more than two users then the
allocation of an optimized resource block to all users is the key parameter to achieve
desired outage efficiency because strong users require higher SNR for higher data
rates and weak users are allocated minimum threshold SNR for lower data rate
requirements to maintain suitable pairing OP and SOP balance
Figure 48 Power radiated by per MMBs antenna
65
So the POMDP policy optimization has shown better performance over the
dynamic programming approach particularly when more users are active (a greater
number of antennas as in Figure 48 the overall radiated power per BS antenna in
downlink has been considerably reduced
43 CONCLUSION AND SCOPE OF FUTURE WORK
431 Conclusion
Starting with LTE (4G) OFDMA has replaced WCDMA with mobile cellular
communications and will also be used during advanced 5G while Non-Orthogonal
Multiple Access (NOMA) has recently been recognized as a groundbreaking PHY
technology in UAV communication NOMA scheme is used in place to increase the
effective use of small resources such as in UAV communication where the data rate
is very low and critical decision making is of utmost importance
The critical need for UAV communication is a secure PHY layer for mission-
critical applications and as NOMA doesnrsquot promise high security the proposed
research work has been carried out to enhance the insecurities of NOMA-UAV
communication In this proposed research work the probabilities of confidential
outage (SOP) and OP were investigated in the two-user NOMA system Here BS is
required to pair a trusted or permissible user with other untrusted users due to the
unequal distribution of untrusted and trusted users in the cell The SIC is then
applied to the receiver side intended for decoding the message signals The Pair OP
of both users has been analyzed for varying Target Secrecy Rate (Rs) of the trusted
user U1 which provides constraint threshold of the SOP of U1
By varying the distance of Untrusted users from BS the optimal distance and power
allocation factor for the feasible pairing of trusted and untrusted users without
compromising the secrecy outage probability of U1 has been achieved in simulation
results
POMDP has provided the optimal power allocation as a resource allocation
algorithm in the dynamically changing environment of two user NOMA cases
where the distance between BS and untrusted user varies significantly The
performance of secure NOMA-UAV is affected critically by (SOP of User 1) which
66
should be optimally selected to maintain the proposed Pair OP between both users
and the simulation results have supported this optimal outage performance Thus
NOMA-UAV architecture has the potential of providing a secure PHY layer for
mission-critical applications by opting for suitable decision-making resource
algorithm POMDP
431 Scope of Future Work
Furthermore the multiuser scenario with the increased number of Untrusted users
can be analytically verified and simulated in the same direction for NOMA-UAV
communication to improve transmission security and reliability In addition more
adaptive and efficient Resource allocation algorithms for NOMA-UAV networks
with secured performance in real-time applications should be investigated
1
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11
PUBLICATIONS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495449|P a g e
Migration from 4g LTE to Advanced PHY Techniques for
Unmanned Aerial Vehicle (UAV) Communication
Pankaj Patel PHD StudentGujarat Technological UniversityGujarat India
ABSTRACT
UAV (unmanned aerial vehicles) with their high mobility and low cost have found a wide range of applications
during the past few decades Historically UAVs have been primarily used in the military mainly deployed in
hostile territory to reduce pilot losses With continuous cost reduction and device miniaturization small UAVs
are now more easily accessible to the public hence numerous new applications in the civilian and commercial
domains have emerged For the sake of boosting resilience against faults natural disasters and unexpected
traffic the Unmanned Aerial Vehicle (UAV) assisted wireless communication systems can provide a unique
opportunity to cater for such demands in a timely fashion without relying on the overly-engineered cellular
network However for UAV-assisted communication issues of capacity coverage and energy efficiency are
considered of paramount importance Starting with LTE (4G) Orthogonal Frequency Division Multiple Access
(OFDMA) has replaced WCDMA for cellular mobile communications and it will also be employed in advanced
5G yet Non-orthogonal multiple access (NOMA) has been recently recognized as a promising PHY technique
to significantly improve the spectral efficiency of mobile communication networks In this paper we provide an
overview of UAV-aided wireless communications by introducing the basic networking architecture
highlighting the key design considerations as well as the new opportunities to be exploited
Keywords LTE (4G) Non-orthogonal multiple access (NOMA) Unmanned Aerial Vehicle (UAV) Wireless
communication
----------------------------------------------------------------------------------------------------------------------------- ---------
Date Of Submission 26-04-2019 Date Of Acceptance 06-05-2019
----------------------------------------------------------------------------------------------------------------------------- ----------
I INTRODUCTION The use of unmanned aerial vehicles
(UAVs) will grow rapidly in the next decade These
remotely piloted or preprogrammed aircraft are
envisioned for applications in numerous civil
settings including industrial monitoring scientific
data gathering agriculture public safety and search
and rescue Many other applications - presently
unforeseen - will inevitably also arise These
vehicles also known as the unfortunate misnomer of
drones must be integrated into the national
airspace system and into the airspace worldwide A
natural concern in the use of UAV is safety and this
has direct implications for the control and non-
payload communication systems that must be used
to operate it efficiently Similarly navigation and
surveillance functions must be made more reliable
and more accurate Because of these factors many
UAV research development testing and
standardization efforts are underway by
governments industries and academia Despite the
fact that piloted civil aircraft have been flying safely
for decades UAV presents distinct new challenges
in the form of different flight profiles eg low-
elevation flights and more high-dynamic maneuvers
wider required bandwidths eg for video and
different ground site characteristics such as locations
in cluttered areas and lower elevation antennas
In this paper first the evolution of radio
technologies considered in UAV wireless
communication is reviewed in literature survey and
the significant work in the area is highlighted along
with the newest challenges The reminder of this
paper is organized as follows
The promising technology NOMA and its
variants are discussed in section three In Section
four the system model and assumptions are
presented and in section five the comparative
analysis of NOMA with existing popular technology
OFDMA (OMA) is given with simulation
persormance analysis At last the work is concluded
in section five
II LITERATURE SURVEY Drones variously known as unmanned
aerial vehicles (UAVs) unmanned aerial systems
(UAS) or remotely piloted aircraft system (RPAS)
are used in several parts of the world for surveying
and aerial mapping disaster management work
monitoring crop production and infrastructure
activities besides commercial photography and
courier delivery The viability of UAV as a
multipurpose research vehiclehas driven great
RESEARCH ARTICLE OPEN ACCESS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495450|P a g e
interest since recent decades[1] The
basictechnology building blocks responsible for the
current advancesinclude airframes propulsion
systems payloadssafety or protection systems
launch and recovery dataprocessor ground control
station navigation and guidanceand autonomous
flight controllers The following briefsurvey is
focused on the area of navigation guidance
andcontrol of UAVs Various control design for
UAVs has beenproposed ranging from linear to
nonlinear synthesis timeinvariant to parameter
varying and conventional PID tointelligent control
approaches The developed controllershave been
implemented for different aerial platforms
airship(blimp) fixed-wing UAV small scale
helicopteruad-rotors and MAV Wireless
communication systems that include unmanned
aerial vehicles promise to provide cost-effective
wireless connectivity for devices without
infrastructure coverage Compared to terrestrial
communications or those based on high-altitude
platforms on-demand wireless systems with low-
altitude UAVs are in general faster to deploy more
flexibly reconfigured and likely to have better
communication channels due to the presence of
short-range line-of-sight links However the
utilization of highly mobile and energy-constrained
UAVs for wireless communications also introduces
many new challenges In India for the regulation
and safety purpose in commercial and survilence
applications the policy guideliens also introduced
as below
Table 1UAV communication Policy Guidelines for
commercial and surveillance purpose
III MIGRATION FROM 4G LTE TO 5G The fruitful deployment of UAV based
communicationsystems for 4G and beyond future
wireless networks is highlyinvolved in finding joint
solutions to challenge of ubiquitousconnectivity with
both a multitude of devices in a spectralefficient way
as well as with energy-efficient transmissionand
operation of the UAV-BS for maximized and
armonizedcoverage and capacity [2][3] It should be
noted that suitableenergy efficiency for the UAV-
assisted ommunication systemachieves paramount
importance in the overall performance ofthe system
Efficient energy consumption results in
enhancedairtime for the communication system
improving bitsJoulesfor a given energy level
Furthermore coverage and capacityof an aerial cell
are attributed to many factors such as
thetransmission power antenna gains UAV
altitude deploymentenvironment and prominently
radio access technology [4]
4G is the fourth generation of broadband
cellular network technology succeeding 3G and
besides the popular techniques in 3G4G ie
TDMAWCDMAOFDMA a new radio access
technology NOMA is also developed by researchers
to be used in communication networks due to its
capability in increasing the system capacity
Recently non-orthogonality based system designs
are developed to be used in communication
networks and have gained significant attention of
researchers Hence multiple access (MA) techniques
can now be fundamentally categorized as orthogonal
multiple access (OMA) and non-orthogonal
multiple access (NOMA) In OMA each user can
exploit orthogonalcommunication resources either
within a specific time slot frequency band or code in
order to avoid multiple access interference The
previous generations of networks have employed
OMA schemes such as frequency division multiple
access (FDMA) of first generation (1G)time
division multiple access (TDMA) of 2G code
division multiple access (CDMA) of 3G and
orthogonal frequency division multiple access
(OFDMA) of 4G
In NOMA multiple userscan utilize non-
orthogonal resources concurrently by yielding a high
spectral efficiency while allowing some degree of
multiple access interference at receivers Recently
NOMA reputations have climbedsharply as a
fundamental solution to the challenges
encompassingthe next generation wireless networks
[5][6]NOMA has been proved to exhibit improved
spectral efficiencybalanced and air access as
compared to OMAtechnologies[6] with the ability
to cater for multipledevices in the same frequency
time or code resource thusproviding efficient access
to massive connected devices Furthermore NOMA
is also instrumental in reducingthe interference by
employing orthogonal resources as inOrthogonal
Frequency Division Multiple Access
(OFDMA)[7][17] or by sharing a single beam
between multiple users forintra-cluster access and
using NOMA for inter-cluster access[18]Current
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495451|P a g e
studies have focused on provisioning Air to
Ground(A2G) communication services mainly
through placement op- timization under various
viewpoints in literature The performance of UAV
based communication systems hasalso been
addressed for the underlaid Device to Device(D2D)
deployment scenario This work assumed
interferenceraised by D2D network nodes without
considering the presenceof terrestrial BS
Additionally there have been a fewstudies
discussing the performance of NOMA for UAV
basedcommunication system[8] A NOMA enabled
fixedwingUAV deployment was proposed in [8] to
support coveragefor ground users situated outside
BS offloaded location
In general NOMA schemes can be
classified into two types power-domain
multiplexing andcode-domain multiplexing In
power-domain multiplexing different users are
allocated[7][8][9][6][5][1][10] differentpower
coefficients according to their channel conditions in
order to achieve a high systemperformance In
particular multiple usersrsquo information signals are
superimposed at the transmitterside At the receiver
side successive interference cancellation (SIC) is
applied for decoding thesignals one by one until the
desired userrsquos signal is obtained providing a good
trade-offbetween the throughput of the system and
the user fairness In code-domain multiplexing
different users are allocated different codes and
multiplexed over the same time-frequencyresources
such as multi-user shared access (MUSA) sparse
code multiple access (SCMA) and low-density
spreading (LDS) In addition to power-domain
multiplexing and codedomain multiplexing there are
other NOMA schemes such as pattern division
multiple access(PDMA) and bit division
multiplexing (BDM) Although code-domain
multiplexinghas a potential to enhance spectral
efficiency it requires a high transmission bandwidth
andis not easily applicable to the current systems
On the other hand power-domain multiplexinghas a
simple implementation as considerable changes are
not required on the existing networksAlso it does
not require additional bandwidth in order to improve
spectral efficiency Inthis paper the prime focusis on
the power-domain NOMAAlthough OMA
techniques can achieve a good system performance
even with simple receiversbecause of no mutual
interference among users in an ideal setting they
still do not have theability to address the emerging
challenges due to the increasing demands in future
networks andbeyond
The superiority of NOMA over OMA can
besummarized as follows
_ Spectral efficiency and throughput In OMA such
as in OFDMA a specific frequencyresource is
assigned to each user even it experiences a good or
bad channel conditionthus the overall system suffers
from low spectral efficiency and throughput In
contrary inNOMA the same frequency resource is
assigned to multiple mobile users with good and
bad channel conditions at the same time Hence the
resource assigned for the weak user isalso used by
the strong user and the interference can be mitigated
through SIC processesat usersrsquo receivers Therefore
the probability of having improved spectral
efficiency and ahigh throughput will be considerably
increased
_ User fairness low latency and massive
connectivity In OMA for example in OFDMAwith
scheduling the user with a good channel condition
has a higher priority to be servedwhile the user with
a bad channel condition has to wait to access which
leads to a fairnessproblem and high latency This
approach cannot support massive connectivity
HoweverNOMA can serve multiple users with
different channel conditions simultaneously
thereforeit can provide improved user fairness lower
latency and higher massive connectivity
_ Compatibility NOMA is also compatible
with the current and future communication
systemssince it does not require significant
modifications on the existing architecture For
exampleNOMA has been included in third
generation partnership project long-term
evolutionadvanced (3GPP LTE Release 13)
Figure 1Pictorial comparison of NOMA Vs OMA
Although NOMA has many features that
may support next generationsit has some limitations
that should be addressed in order to exploit its full
advantage set Thoselimitations can be pointed out
as follows In NOMA since each user requires to
decode thesignals of some users before decoding its
own signal the receiver computational
complexitywill be increased when compared to
OMA leading to a longer delay Moreover
informationof channel gains of all users should be
fed back to the base station (BS) but this results in
asignificant channel state information (CSI)
feedback overhead Furthermore if any errors
occurduring SIC processes at any user then the error
probability of successive decoding will beincreased
As a result the number of users should be reduced to
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495452|P a g e
avoid such error propagationAnother reason for
restricting the number of users is that considerable
channel gain differencesamong users with different
channel conditions are needed to have a better
network performance
IV NOMA UPLINK AND DOWNLINK
SCENERIO SIMULATION ANALYSIS In this section an overview of NOMA in
downlink and uplink networks is introduced
throughsignal-to-interference-and-noise ratio (SINR)
and sum rate analyses Then high signal-to-
noiseratio (SNR) analysis has been conducted in
order to compare the performances of OMA
andNOMA techniques[10]
A Downlink NOMA Network
At the transmitter side of downlink NOMA
network as shown in Fig 2 the BS transmits
thecombined signal which is a superposition of the
desired signals of multiple users with different
allocated power coefficients to all mobile users At
the receiver of each user SIC process isassumed to
be performed successively until userrsquos signal is
recovered Power coefficients ofusers are allocated
according to their channel conditions in an inversely
proportional mannerThe user with a bad channel
condition is allocated higher transmission power
than the one which has a good channel condition
Thus since the user with the highest transmission
power considers the signals of other users as noise
and recovers its signal immediately without
performing anySIC process However other users
need to perform SIC processes In SIC each userrsquos
receiverfirst detects the signals that are stronger than
its own desired signal Next those signals
aresubtracted from the received signal and this
process continues until the related userrsquos own signal
is determined Finally each user decodes its own
signal by treating other users with lower
powercoefficients as noise The transmitted signal at
the BS can be written as
s = aiPsxi
L
i=1
where xi is the information of user i (Ui)
with unit energy Ps is the transmission power atthe
BS and ai is the power coefficient allocated for user
i subjected to ai = 1Li=1 and a1gea2gehellip geaL since
without loss of generality the channel gains are
assumed to be ordered as h1 2 le h2 2 le⋯ hL 2 where hL is the channel coefficient of Lth
user based on NOMAconcept The received signal
at lth user can be expressed as follows
y1 = hls + nl = hl aiPsxi + nlL
i=1
where nlis zero mean complex additive Gaussian
noise with a variance of σ2
(1) SINR analysis By using (2) the instantaneous
SINR of the lth user to detect the jth user jle l
with jne L can be written as
SINRl = alγ hl 2
γ hl 2 aiLi=l+1 + 1
Where γ = Psσ2 denotes the SNR
(2) Sum rate analysis After finding the SINR
expressions of downlink NOMA the sumrate
analysis can easily be done The downlink
NOMA achievable data rate of lth user can
beexpressed as
RlNOMA-d
= log2 1 + SINRl = log2(1 +alγhl2γhl2 i=l+1Lai+1
B Uplink NOMA Network
In uplink NOMA network as depicted in
Fig 3 each mobile user transmits its signal to the
BS At the BS SIC iterations are carried out in order
to detect the signals of mobile users By assuming
that downlink and uplink channels are reciprocal and
the BS transmits power allocation coefficients to
mobile users the received signal at the BS for
synchronous uplink NOMA can be expressed as
r = hi aiPxi + n
L
i=1
where hi is the channel coefficient of the ith
user Pxi is the maximum transmission power
assumed to be common for all users and n is zero
mean complex additive Gaussian noise with a
variance of σ2
Figure 2Downlink NOMA network
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495453|P a g e
Figure 3 Uplink NOMA network
1) SINR analysis The BS decodes the signals of
users orderly according to power coefficientsof
users and then the SINR for lth user l ne 1 can
be given by
SINRl =alγ hl 2
γ ai hi 2 + 1lminus1i=1
where γ =P
σ2
2) Sum rate analysis The sum rate of uplink
NOMA when γ minus infincan be written as
Rsum NOMA-u asymp log2(γ hl 2L
l=1
C Comparing NOMA and OMA
The achievable data rate of the lth user of OMA for
both uplink and downlink can be expressed
RsumOMA = αl log2(1 +
βlγ hl 2
αl)L
l=1
For the sake of simplicity sum rates of
uplink NOMA and OMA can be compared for
twousers Then using both the sum rate of uplink
NOMA and OMA at high SNR can beexpressed
respectively as
RsumNOMAasymp log2 γ h1 2 + γ h2 2
Here we notice ROMA
sumle RNOMA
sum
Fig shows that NOMA outperforms OMA in terms
of sum rate in both downlink and uplinkof two
user networks
V SIMULATION RESULTS
The Comparative analysis of modelling
Downlink and Uplink NOMA in comparison with
OMA is simulated and findings are presented that
shows superiority of NOMA over OMA with better
spectral efficiency for simulation parameters taken
as power allocation coefficients a1=06 a2=04 and
channel responses h1 2
=0 DB h22=20 DB
parameters
Figure 4NOMA UPLINK
Figure 5 NOMA DOWNLINK
VI CONCLUSION This paper investigated an account of
NOMArsquos applicability for UAV-assisted
communication systems NOMA schemes are
proposed to improve the efficient usage of limited
network sources OMA based approaches that use
time frequency or code domain in an orthogonal
manner cannot effectively utilize radio resources
limiting the number of users that can be served
simultaneously In order to overcome such
drawbacks and to increase the multiple access
efficiency NOMA technique has been recently
proposed Accordingly users are separated in the
power domain Such a power domain based multiple
access scheme provides effective throughput
improvements depending on the channel conditions
The crucial need of UAV communication of
optimum utilization of available licensed spectrum
bandwidth is considered here and simulation results
taken presented that NOMA performs better than
OMA while fulfilling individual user-rate constraint
for both users The research work can be further
carried out investigating joint power and phase
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495454|P a g e
allocation of UAV nodes deployment for efficient
operations
REFERENCES [1] S M I C Y L M I Muhammad Farhan Sohail
Non-Orthogonal Multiple Access for Unmanned
Aerial Vehicle Assisted Communication in IEEE
access 2018
[2] M Mozaffari Drone small cells in the clouds
Design deployment and performance analysis in
IEEE Global Communications Conference 2015
[3] R Z a T J L Y Zeng Wireless
communications with unmanned aerial vehicles
opportunities and challenges in IEEE
communication magazine 2016
[4] I B-Y a H Yanikomeroglu The new frontier in
ran heterogeneity Multi-tier drone-cells IEEE
Communications Magazine pp 48-55 2016
[5] P K S a D I Kim Uav-enabled downlink
wireless system with NOMA access in IEEE
Globecom Workshops Dec 2017
[6] P Xu and K Cumanan Optimal power allocation
scheme for nonorthogonal multiple access with
fairness in IEEE Journal on Selected Areas in
Communications oct 2017
[7] E H a D I K S Ali Non-orthogonal multiple
access (noma) for downlink multiuser mimo
systems User clustering beamforming and power
allocation in IEEE Access 2017
[8] W S M B a M D M Mozaffari Unmanned
aerial vehicle with underlaid device-to-device
communications Performance tradeoffs in IEEE
Transactions on Wireless Communications June
2016
[9] Z D X D a R Z Z Chen An optimization
perspective of the superiority of noma compared to
conventional oma in IEEE Transactions on
Signal Processing Oct 2017
[10] M T Mahmoud Aldababsa1 and S G G K 2 A
Tutorial on Non-Orthogonal Multiple Access
2017
[11] X L Z J W a K J R L Zhu Han Delay
Sensitive Scheduling Schemes for Heterogeneous
QoS over Wireless Networks IEEE
TRANSACTIONS ON WIRELESS
COMMUNICATIONS VOL 6 NO 2
FEBRUARY 2007 vol 6 no 2 2007
[12] Z J W a K J R L Z Han A resource
allocation framework with credit system and user
autonomy over heterogeneous wireless networks
in IEEE Global Telecommunications Conference
2003
[13] N B S a P S S Chen Heterogeneous delay
tolerant task scheduling and energy management in
the smart grid with renewable energy IEEE
Journal of Selected Areas in Communications vol
31 no 07 pp 1258-1267 july 2013
[14] H L Z C a Z H Y Hu Scheduling strategy for
multimedia IEEE Transactions on Vehicular
Technology July 2016
[15] P F a K B L Y Dong High-speed railway
wireless communications efficiency vs fairness
IEEE Transactions on Vehicular Technology vol
63 no 2 pp 925-930 march 2014
[16] T R a Z H Z Chang Queueing game for
spectrum access in cognitive radio networks
IEEE Communications Letters vol 19 no 11 pp
2017-2020 June 2015
[17] Z C L T R a Z H F I Yun Hu Service
Provisioning and User Association for
Heterogeneous Wireless Railway Networks IEEE
Transactions on Communications 2017
[18] H S W Tianti Chen Optimal Scheduling for
Wireless On-Demand Data Packet Delivery to
High-Speed Trains IEEE Transactions on
Vehicular Technology vol 64 no 9 pp 4101 -
4112 september 2015
Pankaj Patel Migration from 4g LTE to Advanced PHY Techniques for Unmanned Aerial
Vehicle Communication International Journal of Engineering Research and Applications
(IJERA) Vol 09 No04 2019 pp 49-54
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Improving Of Physical Layer Insecurity Of The
Non Orthogonal Multiple Access System
Pankaj M Patel Prof Dr Chetan B Bhatt
Abstract The key aspect of the NOMA (power domain non orthogonal) is the user possibility for decoding the messages belonging to another pair users
on similar resources The method interprets a security threat especially in the case where the base station serves the users with various security
clearance or untrusted users The main aspect of NOMA is to serve the multiple users upon the similar radio resources at the minimal inter user
interference expense The system not only permits the serving of particular users with high efficient bandwidth but also permits the scheduling more type
of users than the timely available users In this study we investigated the secrecy outage probability (SOP) and OP in the both two user and multi user
NOMA system where the BS is supposed to pair a trusted or legitimate user with other untrusted users because of the un even distribution of the
untrusted and trusted users in the cell SIC the successive interference cancellation was then implemented at the receiver side for decoding the
message signals With the application of NOMA concept the study investigated the pair outage behavior under the SOP constraints on the trusted users
In specific the SOP and OP of the concerned U1 were obtained in the closed type of expressions The study also provided the understanding the
possibility of obtaining an optimal outage efficiency for pairing under the SOP constraints With certain numerical simulations the study verified the
effectiveness of the analytical derivations with respect to various scenarios
Index Terms NOMA Secrecy outage Probability Successive Interference Cancellation bandwidth channel state information etc
mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash
1 INTRODUCTION The physical layer security and non-orthogonal multiple
access was regarded as the encouraging techniques for the
processing of wireless communication network systems Today
the combination of the two significant communication methods
was studied to guarantee a spectral efficient and secure
wireless transmission Most of the prevailing works
predominantly concentrated on the optimization and efficiency
of the PLS in the existence of untrusted relay nodes and
external eavesdroppers(Arafa et al 2019a)But there occurs a
gap in the theoretical studies to describe the ease of obtaining
the enhanced efficiency in the existence of untrusted users
Recently the network traffic amount have greatly enhanced
particularly with the updated growth in IoT applications in
future To rectify the huge traffic demand upcoming wireless
networks must deliver a best spectral effectiveness and large
connectivity (Sun et al 2018) NOMA is regarded as the best
technology in which various NOMA technique exhibit similar
concept of providing several users at the similar frequency and
time The famous NOMA types are code domain and power
domain that provided enhanced efficiency when compared
with the existing techniques The paper adopted the power
domain on the basis of super position coding (transmitter side)
at the SIC (receiver side) Hence the users could possess the
key for the messages of other users and thereby utilize SIC for
removing the interference (Cao et al 2019) (Zhao et al
2018) Hence various NOMA methods was proposed for
allowing the adjacent users to perform as a relay for improving
the efficiency of the weak users through the resending of
decoded data in a next time slot The weak user could utilize
the MRC technique to integrate the information achieved in
different time slots In addition obtaining a secured
communication is a crucial problem over the vulnerable
wireless networks to security threats mainly because of the
broadcasted transmission nature
The study investigated the secrecy performance and outage
with the untrusted user(Furqan et al 2019) The main aspect
of the study is to analyze the feasibility of achieving the OP of
the pair under a trusted user Because of the decoding facility
and spectrum sharing of SIC the untrusted user could perform
as a eavesdropper
Figure 1 Representation of Base station
Figure 1 depicts the representation of base station The main
aim of the proposed system defined as
bull To investigate the outage probability of the proposed
system
bull To investigate the SOP of the proposed system
bull To derive the accurate expression of the outage
probability for all kind of scenarios and closed form of
expressions for few special cases and verifying them
numerically for yielding a better outage efficiency
2 RELATED WORKS This section describes the different existing techniques and
methods related as our proposed system (Cao et al
2019)suggested two kinds of relay selection process denoted
as AF (amplify and forward) and DF (decode and forward) on
the basis of AORS and DORS for achieving secure and
reliable NOMA systems under the untrusted users The study
derived the accurate and asymptotic closed form of the SOP
expressions and the PSCP obtained by the two methods and
investigated the optimized feature of the two methods The
____________________________________
bull PANKAJ M PATEL is currently pursuing PHD program in Electronics
amp Communication in Gujarat Technological University E-mail
pankajmphd24gmailcom
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complete analysis and the simulation results represented that
both the AORS and DORS characteristically outperformed the
benchmark system apart from obtaining the similar SOP and
the required PSCP at very high Signal to noise ratio (Zhang et
al 2018)Investigated the power allocation and joint subcarrier
issue for NOMA ndashAF two-way relay networks with restrictions
The study focused to optimize the obtainable secrecy
efficiency by designing jointly the SC task power allocation
and user pair scheduling The paper suggested a SCAS-1
technique by assuming the appropriate information about the
channel state information in the relay station followed by the
formulation of SCAS-2The secured power allocation issue is
structured as a convex programming issue and then resolved
by in-depth point techniques The results of simulation
explained that the efficiency of the suggested SSPA algorithms
with and without CJ respectively (Arafa et al
2019b)Considered a downlink system where the base station
is connecting with two appropriate users in two various
scenarios in the unsecured environments which are the
presence of the eavesdropper and untrusted relay
communication In the first process several trusted
cooperative relays is engaged for assisting with the base
station transmission and protect the corresponding signals
from the eavesdropper Several relay methods are framed and
investigated for the following process which are forward and
decode cooperative jamming and AFFor all the technique
secured beam forming signals were formulated at the relays
for maximizing the obtainable secret rate areas For the next
process with untrusted relay the obtained secrecy rate areas
obtained for two various relay schemes which are AF and CF
under two various operation modes In the first process the
prescribed users will receive the signals from the untrusted
relay and the base station for decoding the messages The
study depicted that the efficient relay scheme is highly
dependent on the parameters of the system especially the
nodal distance and the secrecy rate area (Sun et al
2018)Studied the algorithm for resource allocation for MISO
systems where the full duplex BS serve several half duplex
downlink and uplink users on the similar subcarrier The
allocation of the resource have been optimized for maximizing
the weight system output whereas the leakage of information
was restricted and an artificial noise was induced for granting
secured communication with respect to potential
eavesdroppers The study formulated a novel non-convex
optimization issue by considering the imperfect CSI of the
channels and requirements of QoS of legitimate users The
simulation results stated the efficiency of the optimal algorithm
was related to the suboptimal algorithm Apart from that the
suggested MISO NOMA technique not only guarantee uplink
and downlink communication purpose for security but delivers
a characteristic rate of system secrecy when compared with
the conventional MISO and other two baseline methods
(Dang et al 2017)Analysed the outage efficiency of various
multicarrier relay selection techniques for 2 hop OFDM system
in Poisson relay fields The study concentrated on DF relay
systems with more selection schemes The accurate
expressions for the OP are provided in integrals generally
Apart from that asymptomatic derivatives for OP in the SNR
region in the fixed circle area are predicted for both relay
selection techniques in closed forms Consequently several
significant factors that are linked to the cooperative network
were examined comprising OP ratio of two selection
techniques diversity and subcarrier optimization output In
conclusion a structure to analyze the OP of OFDM with
spatially random relay have been constructed that could be
easily altered for analyzing same case with various forwarding
protocols channel conditions and location distributors (Dang
et al 2018)Proposed a full duplex OFDM ndashD2D system in two
hop network where DF relays help the transmission from DUE
transmitter to DUE receiver The study also investigated the
OP issue by integrating the transmit power within the DUE
relays and transmitter and to deliver a suboptimal solution that
can improve the outage performance The investigations are
validated by Monte Carlo simulations These results described
could furnish an insight into full duplex OFDM system and
guides for the application in the next generation network
(Kokshoorn et al 2016) suggested a robust channel algorithm
for mmWave systems on the basis of novel overlapped pattern
design With the use of finite measurements the study
depicted that this decreased measurements was found ENR of
25 dB to obtain the similar PEEFor the appropriate channel
with quickly altering channel information the price might be
acceptable for improving the speed of estimation The study
also proposed a robust channel estimation algorithm where
the additional calculations are carried out when expecting
more estimation error The study depicted that the channel
could be measured more effectively resulting in noteworthy
gains upto 6 dB when comparing with the existing algorithm
(Ali et al 2016) described the variations in the principles of
downlink and uplink NOMA transmissions in a wireless
system The study formulated a maximization issue in a cell
like the user clustering and power allocations Because of the
integral nature of the formulated programming issue the study
solved the issue in to steps which are grouping of users into
clusters and then to optimize the corresponding power
allocations The study proposed a sub optimal scheme that
exploited the gain variations in NOMA groups and clusters into
multiple and single clusters for enhancing the sum-throughput
The results compared the efficiency of OMA and NOMA in
different network scenarios (Lv et al 2017) investigated a
MCR-NOMA where the multicast user functions as relays to
enhance the efficiency of both secondary and primary
networks On the basis of the available CSI three various
secondary user schedule techniques for processing MCR-
NOMA were depicted For evaluating the system efficiency the
study derived the closed form of expressions of OP and order
of diversity for both the networks It has been described that
more spatial temporal diversity could be obtained by using the
CSI for scheduling of the secondary user (Liu et al 2016)
considered a MIMO ndashNOMA scenario for investigating a
dynamic clustering issue in an logical perspective To resolve
the problem of optimization issue three algorithms named top
down A and B bottom up were suggested for realizing various
complexity tradeoff and worst user throughput The study
noted that the top down B algorithm could obtain a better
tradeoff between throughput and complexity amongst the
applied procedures (Fianu and Davis 2018) investigated
three various rules of allocation and demonstrated the optimal
policy as an available inventory function The study also
provided the country level estimation of requirements that are
not met and the determination of the probability distribution
linked with the total undeserved counties The study have
been done for depicting the policy of allocation with respect to
effectiveness and equity (Hou et al 2018) studied the socio
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graphical impact on the mobile video services and thereby
suggested a CTMDP on the basis of resource allocation
technique by considering social graphs as the constraints
With the use of relative value an optimized policy could be
achieved that aimed at increasing the reward regarding the
average system The simulation depicted that the suggested
CTMDP obtained an increased efficiency against the state of
art methods
3 PROPOSED WORK
Fig 2 Proposed flow depicting the overall mechanism
The proposed(Interference mitigation using POMDP) overall flow
is depicted in the figure 2 After setting up of the base station the
distance between the base station and the user was determined
and if the distance is less than 200 meters it is decided as trusted
users and if it is greater than 200 m it is defined as untrusted
users In case of untrusted users the channel state information is
subjected to POMDP (Partially observable Markov Decision
Process) followed by resource allocation The performance
analysis have been done after the system The work considered
a NOMA oriented cellular setup provided with a base station at
the centre and two users as shown in the figure 2 The adjacent
(near) user possess high level of security clearance that is
required for securing with physical layer from the low
securityuntrusted clearance user (U2) that is located at a faraway
distance from the base station P is defined as the maximum
transmit power level (base station)In this paper it is assumed that
all the network nodes are installed with single antenna and further
all the channels are considered to be identical independently
quasi static with Rayleigh distribution with respect to distribution
119862119873(0 120575 frasl
120596 frasl
) In which 120575 is the distance in-between the BS
and nodes 119880 Here path-loss exponent and path-loss constant is
represented as 120572 and 120596 In addition it is assumed that base
station predicted the user location so that a better CSI is
obtainable at base station that is involved in pairing the users
The base station transmits the superimposed mixture
119909 = radic119905 119904 + radic1 minus 119905 119904
In which 119904 119904 are the unit power signals received by users 119880 and
119880 respectively 119905 is the power
allocation coefficient for the adjacent user
119903 = ℎ 119909 radic119875 + 119899
119903 = ℎ 119909 radic119875 + 119899
where ℎ ℎ - the channel gain linked with the
small-scale fading from the base station to users 119880 and 119880
respectively 119899 and 119899 are the extra white Gaussian noise with
variance and zero mean 1198730 and it is assumed that 120588 = 1198751198730 is
the BS convey signal-to-noise ratio (SNR) In NOMA technique
farther user that possess more power
could decode its own signal by considering the adjacent signal as
a noise without decoding the adjacent user message In the
preceding equation it is assumed that U1 first decode the weak
signal followed by decoding its own signal with SICU2 which is
the untrusted user attempted to decode the near user message
after the decoding of the adjacent user messages after the
process of decoding its own message with SICHence the
following equation have been achieved
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119879119900119905119886119897 = 119878119868119873119877 119878119868119873119877
119878119868119873119877 119878119868119873119877
+
where 119878119868119873119877 represented the signal-to-interference-plus-noise-
ratio of user 119898 that was decoded by 119880 for 119898119899120598119894 2+ and the
channels gain of 119880 denoted by |ℎ |
followed an exponential distribution
with the parameter 120577 = 120596 120575
Problem Formulation
Hence the base station should achieve and serve a better
communication for the users who are susceptible to security
threat from untrusted user the proposed system defined two
kinds of QoS efficiency measures that could be regarded to be
important for framing the issue In specific the study defined a pair
of OP to check the reliability of the QoS satisfaction In general
the pair OP is stated as the probability in which the obtainable
data rates dor the users equal to or greater than the least target
threshold The next metric also called as the SOP is the
probability that the non negative secrecy capacity obtained by the
trusted user is more than the threshold value
The following issue aimed at reducing the pair OP subjected to a
SOP factor for the user U1 that is provided by
min
119875
0 lt 119905 lt 05
119878119874119875 le 120573
in which 119875 119878119874119875 and 120573 are the pair OP SOP(119880 ) and the
permissible SOP threshold
4 PERFORMANCE ANALYSIS
Derivation of the Pair OP
With the use of Shannonrsquos capacity formula and considering
119862 and 119862
as the threshold capacities of users 119880 and
user 119880 respectively the OP of the pair could be provided
by
119875 = 1 minus 119876 119909119876
in which
120591 = 2
119898 120598 119894 2+
120601 =
( )
120601 =
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119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 1 120601 gt 120601
For having 120601 gt 120601 the constraint on
the power allocation factor (t) needs to be satisfied
(119905 gt
) and for this case 119876 could be obtained as
follows
119876 = exp (
)
lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 2 120601 lt 120601
Like case 1 it was stated that opposite constraint on
a as (119905 lt
) and
119876 can be derived as follows
119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
The OP of the NOMA pair
119875 = 1 minus 119891(119905)119896 (119905)
lt 119905 lt
1 minus 119891(119905)119896 (119905) 0 lt 119905 lt
in which
119891(119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
Derivation of SOP of 119880
With Shannonrsquos capacity formula the secrecy rate of
user 119880 was provided by
119878119862 = 119869 minus 119869
119869 = log (1 + 119879119900119905119886119897 (r (1)))
119869 = log (1 + 119879119900119905119886119897 (r (2)))
119878119862 is the non-negative secrecy capacity of 119880 Provided the
secrecy capacity in the SOP of 119880 is
119878119874119875 = 1 minus 120584119890
119860 =
120584 =
119879 - the user 119880 secrecy target rate
Theorem 1
Outage-optimal power allocation factor
119905 = radic
( )
In which 119908 =
119908 =
119911 = 1 + 120591
The minimum power allocation factor (119886 )
119905 =
(
)
The optimal OP of the NOMA pair under the SOP constraint
=
( )
( ( ))119890
( )
That is lt 0whih meant that the U1 (SOP) is a reducing function
Of t that results in the optimal power allocation factor that is
greater than 119905 for the satisfaction of secrecy constraining
factorPartially observable Markov decision process S is
represented as statesLet D is the channel features which is
consider here as actions the conditional transition probability
between states is regarded as T Reward function R is
calculated as the prediction of maximum capacity channel with
respect to data rate r = R(S x D) the agent receives an
observation o ϵ 120118 o isin Ω display style oin Omega that
depended on the new environment state S and on the just
took action d with the probability O(o|s d)
Reward received at time t is conveyed as r = R(S x D)
H is the belief states over POMDP states
119867 is the belief state transition function
119903 = 119877(119867 x 119863) is the reward function on the belief states
119861 (ℎ 119889 ℎ ) = sum Pr ( 120118 ℎ |ℎ 119889 119900) Pr(119900|119889 ℎ)
Pr(h |h d o) =
1 if the belief update with arguments h d o returns h 0 otherwise
The reward function is updated on the basis of the belief MDP
r (h d) = sum h(s) R(s d) isin
the agent focus on the largest expected immediate rewardin
other words the maximum capacity channel The section
analyse the accuracy of the analytical derivations under
various settings
Figure 3 The feasible pairing
The SOP of U1 with the increasing untrusted user U2 and
distance (d2) for several BS transmits Signal to Noise Ratio
at 120588 = minus20minus1020 119889119861is depicted in with a=005 and 01 and
d1=200m is depicted in the figure The results stated that the
U1(SOP) is a gradually reducing function as per d2 that
implies that the increasing value of d2 leads to the
improvement of the SOP of U1 Since the provided constant
threshold ϵ in SOP restraint U2must be situated at a larger
space when compared with threshold value to obtain the SOP
of U1 Apart from that it is normal that the high the target
secrecy rate rises the SOP of U1
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Figure 4 The Secrecy outage probability
Feasible Pairing in th SOP of pair OP and U1 with the
enhanced power allocation factor (a) in which d2 = 700 m d1
= 200 m 120588 = 15 dB and ϵ = 01 The results depicted that the
the pair OP and SOP of user U1 with increased a for two (d2)
various distances of the (U2) untrusted user The results
approve the convex nature of the pair OP and the SOP curve
is gradually decreasing on the basis of a Generally during the
increase in a the power assigned to the weak user message
decreases that minimize the ability of U2 for discriminating the
superior positioned signals thereby improving the SOP of U1
Figure 5 The Pair outage probability
Pair OP in case of rising U2 untrusted user in distance (d2)
for different base station transfer the signal to noise ratio(120588 =
5 15 25 dB) where a = 015 and d1 = 200 m
Figure 6The infeasible pairing of secrecy outage
probability of the pair OP and U1
The infeasible pairing of SOP (U1) and the pair outage
probability with the enhanced allocation of the power ad1(200
m)d2(300 m)120588 = 15dB and ϵ = 0
The figure 6 depicted that the
The figure 6 shows the similar plotting of the data by altering
the untrusted user location by transferring it to a BS closer
distance (d2 = 300 m) It also depicted that the U1 SOP
constraint of is disrupted at a because the SOP is more than ϵ
The accuracy is well-matched and verified with all range of
numerical simulation The results noticed that the efficiency is
based on the comparative locations of the two user with the
base station
Figure 7 The figure 7 depicts that SNR versus strictly
positive secrecy rate
The observed graph proves that the secrecy capacity
outperforms the existing techniques The proposed precoding
application increases the performance of the system The
transmission power of the system is the power required to
transmit a particular data When there is an increase in the
number of users there is the possibility of inference in the data
transmission and hence the efficiency of the data rate may be
affected Depending on these instances the efficiency of the
antenna capacity to withheld and accommodate the data
determined
Figure 8 The power radiated by BS antenna
In the figure 8with respect to the simulation setup the
precoding methods are performed based on the radiated
power per BS antenna is depicted The results observed the
better efficiency of the proposed system The proposed proves
to be better when compared with existing linear precoding
methods in the prescribed three metrics thereby stating that
MRT may be utilized for the the examination of the secrecy
capacity Our proposed technique spends less radiatated
power thereby increasing the overall capacity of the system
5 CONCLUSION The NOMA system decodes the messages of other user pairs
on the similar resources thereby promoting user possibility
The technique interprests a security threat in which the BS
serves the untrusted users The study analysed the SOP and
OP in both multi user and two user NOMA system in which the
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base station pairs the trusted user in closed type of
expressions The proposed (Interference mitigation using
POMDP) also enable the understanding of possibility of
achieving outage optimal efficiency to pair under SOP
constraints The numerical verifications verified the efficiency
of the analytical derivations
6 REFERENCES [1] ALI M S TABASSUM H amp HOSSAIN E 2016
Dynamic user clustering and power allocation for
uplink and downlink non-orthogonal multiple access
(NOMA) systems IEEE access 4 6325-6343
[2] ARAFA A SHIN W VAEZI M amp POOR H V
2019a Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
15 210-222
[3] ARAFA A SHIN W VAEZI M amp POOR H V
2019b Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
[4] CAO K WANG B DING H LI T amp GONG F
2019 Optimal Relay Selection for Secure NOMA
Systems under Untrusted Users IEEE Transactions
on Vehicular Technology
[5] DANG S CHEN G amp COON J P 2018
Multicarrier relay selection for full-duplex relay-
assisted OFDM D2D systems IEEE Transactions on
Vehicular Technology 67 7204-7218
[6] DANG S COON J P amp CHEN G 2017 Outage
performance of two-hop OFDM systems with
spatially random decode-and-forward relays IEEE
Access 5 27514-27524
[7] FIANU S amp DAVIS L B 2018 A Markov decision
process model for equitable distribution of supplies
under uncertainty European Journal of Operational
Research 264 1101-1115
[8] FURQAN H M HAMAMREH J amp ARSLAN H
2019 Physical Layer Security for NOMA
Requirements Merits Challenges and
Recommendations arXiv preprint arXiv190505064
[9] HOU L ZHENG K CHATZIMISIOS P amp FENG Y
2018 A Continuous-Time Markov decision process-
based resource allocation scheme in vehicular cloud
for mobile video services Computer
Communications 118 140-147
[10] KOKSHOORN M CHEN H WANG P LI Y amp
VUCETIC B 2016 Millimeter wave MIMO channel
estimation using overlapped beam patterns and rate
adaptation IEEE Transactions on Signal Processing
65 601-616
[11] LIU Y ELKASHLAN M DING Z amp
KARAGIANNIDIS G K 2016 Fairness of user
clustering in MIMO non-orthogonal multiple access
systems IEEE Communications Letters 20 1465-
1468
[12] LV L CHEN J NI Q amp DING Z 2017 Design of
cooperative non-orthogonal multicast cognitive
multiple access for 5G systems User scheduling and
performance analysis IEEE Transactions on
Communications 65 2641-2656
[13] SUN Y NG D W K ZHU J amp SCHOBER R
2018 Robust and secure resource allocation for full-
duplex MISO multicarrier NOMA systems IEEE
Transactions on Communications 66 4119-4137
[14] ZHANG H YANG N LONG K PAN M
KARAGIANNIDIS G K amp LEUNG V C 2018
Secure communications in NOMA system
Subcarrier assignment and power allocation IEEE
Journal on Selected Areas in Communications 36
1441-1452
[15] ZHAO T LI G ZHANG G amp ZHANG C-X
Security-Enhanced User Pairing for MISO-NOMA
Downlink Transmission 2018 IEEE Global
Communications Conference (GLOBECOM) 2018
IEEE 1-6
Originality Report Certificate
It is certified that PhD Thesis titled lsquoHeterogeneous Wireless Network using Non-
Orthogonal Multiple Access Method in 5G for Secret Communicationrsquo by Shri
Pankaj Manubhai Patel has been examined by us We undertake the following
a The thesis has significant new workknowledge as compared to already
published or is under consideration to be published elsewhere No sentence
equation diagram table paragraph or section has been copied verbatim from
previous work unless it is placed under quotation marks and duly referenced
b The work presented is original and the own work of the author (ie There is no
plagiarism) No ideas processes results or words of others have been presented
as the Authors own work
c There is no fabrication of data or results which have been compiledanalyzed
d There is no falsification by manipulating research materials equipment or
processes or changing or omitting data or results such that the research is not
accurately represented in the research record
e The thesis has been checked using (copy of originality report attached) and found
within the limits as per GTU Plagiarism Policy and instructions issued from time
to time (ie Permitted similarity index lt=25)
Signature of the Research Scholar Date 17092021
Name of Research Scholar Pankaj Manubhai Patel
Place Ahmedabad
Signature of Supervisor Date 17092021
Name of Supervisor Dr Chetan B Bhatt
Place Ahmedabad
132
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SODH PAPER FOR PLAGRIASMdocxDocument SODH PAPER FOR PLAGRIASMdocx (D47816804)
1
PhD THESIS Non-Exclusive License to
GUJARAT TECHNOLOGICAL UNIVERSITY
In consideration of being a PhD Research Scholar at GTU and in the interests of the
facilitation of research at GTU and elsewhere I Pankaj Manubhai Patel has Enrollment
No139997111012 hereby grants a non-exclusive royalty-free and perpetual license to
GTU on the following terms
a) GTU is permitted to archive reproduce and distribute my thesis in whole or in part
andor my abstract in whole or in part (referred to collectively as the ldquoWorkrdquo) anywhere
in the world for non-commercial purposes in all forms of media
b) GTU is permitted to authorize sub-lease sub-contract or procure any of the acts
mentioned in paragraph (a)
c) GTU is authorized to submit the Work at any National International Library under
the authority of their ldquoThesis Non-Exclusive Licenserdquo
d) The Universal Copyright Notice (copy) shall appear on all copies made under the authority
of this license e) I undertake to submit my thesis through my University to any Library
and Archives Any abstract submitted with the thesis will be considered to form part of
the thesis
f) I represent that my thesis is my original work does not infringe any rights of others
including privacy rights and that I have the right to make the grant conferred by this
nonexclusive license
g) If third party copyrighted material was included in my thesis for which under the terms
of the Copyright Act written permission from the copyright owners is required I have
obtained such permission from the copyright owners to do the acts mentioned in paragraph
(a) above for the full term of copyright protection
h) I retain copyright ownership and moral rights in my thesis and may deal with the
copyright in my thesis in any way consistent with the rights granted by me to my
university in this non-exclusive license
i) I further promise to inform any person to whom I may hereafter assign or license my
copyright in my thesis of the rights granted by me to my university in this non-exclusive
license
j) I am aware of and agree to accept the conditions and regulations of a PhD including
all policy matters related to authorship and plagiarism
Signature of the Research Scholar
Name of Research Scholar Pankaj Manubhai Patel Date 17092021
Place Ahmedabad
Signature of Supervisor
Name of Supervisor Dr Chetan B Bhatt Date 17092021
Place Ahmedabad
Seal
i
ABSTRACT
The landscape of future fifth-generation (5G) radio access networks is
expected to seamlessly and ubiquitously connect everything and
support higher traffic volumes densely connected wireless devices and
diversified requirements on reliability latency battery lifetime etc as
opposed to the current fourth-generation (4G) cellular networks
Moreover in unexpected or emergencies (such as disaster relief and
service recovery) the deployment of terrestrial infrastructures is
economically infeasible and challenging due to high operational
expenditure as well as sophisticated and volatile environments To
address such novel issues intelligent heterogeneous architecture by
leveraging unmanned aerial vehicles (UAVs) (or commonly known as
drones) has been considered to be a promising new paradigm To
improve the system performance of UAV communication in 5G
networks physical layer techniques are of much concern as they affect
the applications of UAVs significantly In this research work security
aspects of NOMA-based UAV communication network have been
considered for optimization as physical layer security in a wireless
communication network is not as robust as wired communication due to
fading and varying SNR scenarios Here primarily two usersrsquo models
as the trusted and untrusted user communicating with BS have been
optimized for outage-optimal performance considering pair Outage
probability and Secrecy outage probability as performance metrics The
achieved results are extended to multi-user scenarios also and for the
optimal policymaking dynamic programming and Partially Observable
Markov Decision Process (POMDP) optimization approaches have
ii
been simulated and verified The simulated results have shown that
POMDP has potential consideration as a resource scheduling
optimization technique in the NOMA-UAV communication network for
providing secure and more robust performance
iii
Acknowledgment
Completing a PhD is a tough task that requires hard work and a lot of effort This is
often an overwhelming but also great experience that I would not have been able to
complete without the assistance and support of so many people Thus it is my great
pleasure to thank all those people First of all I would like to thank almighty for giving
me the strength to carry out this task I would like to deeply thank Dr Chetan B Bhatt
my supervisor for his guidance encouragement and support over these years This
research work would not have been possible without his constructive pieces of advice his
systematic guidance and his patient support thought out the duration of my research work
I would like to express my sincere gratitude to Dr Harshal A ALOORKAR and Dr
KIRAN R TRIVEDI Dr Mehul Raval my doctoral progress committee members Their
rigorous style of reviewing and constructive feedback with valuable suggestions of Dr
Prakash Gajjar Mr Hitesh Panchal and Mrs Monali Mandli who spent their valuable
time whenever required for discussing aspects of this work and provided relevant material
as well Mr Parth Modi and Mr Jagadish Patankar to initiate and inspired me a lot to
continue my work Mr Mukesh Sharma who help in maintain documents I am also
thankful to my parents and family members who always stood with me in each critical
situation and supported me endlessly I am thankful to all EC departments of various
polytechnic and degree engineer colleges for their cooperation in every possible means
Lastly I would thank all the people who directly or indirectly helped me during this very
important phase of my life
Pankaj Manubhai Patel
vi
List of Abbreviation
3GPP 3rd Generation Partnership Project
5G Fifth Generation
A2G Air to Ground
AWGN Additive White Gaussian Noise
BDM Bit Division Multiplexing
BS Base Station
BPCU Bits Per Channel Use
CDMA Code Division Multiple Access
CR Cognitive Radio
CSI Channel State Information
CNPC Control and Non-Payload Communications
CRN Cognitive Radio Networks
D2D Device-to-Device
DCP Difference of Concave Programing
DOMP Dynamic Optimization Method of Programming
FR Floating Relay
GSM Global System for Mobile Communications
HLPSL High-Level Protocol Specification Language
ICT Information and Communication Technology
IoT Internet of Things
IRS Intelligent Reflecting Surface
IMT Information Management Technology
vi
LDS Low-Density Spreading
LTE Long Term Evolution
LTE-A Long Term Evolution Advance
MCR Multicast Cognitive Radio
MI Mobile Internet
MIMO Massive Multiple-Input Multiple-Output
mm-Wave millimeter Wave
MTC Machine-Type Communication
MUSA Multi-User Mutual Access
NOMA Non-Orthogonal Multiple Access
OFDMA Orthogonal Frequency Division Multiple Access
OMA Orthogonal Multiple Access
OP Outage Probability
POMDP Partially Observable Markov Decision Process
PLS Physical Layer Security
PDMA Pattern Division Multiplexing Control
PUN Primary User Networks
QoS Quality of Service
RIS Reconfigurable Intelligent Surface
RNRF Random Near-Random Far
Rs Target Secrecy Rate
SAGIN Space-Air-Ground Integrated Networks
SIC Successive Interference Cancellation
STBC Space-Time Block Coding
vi
SBF Secrecy Beam Forming
SCMA Sparse Code Multiple Access
SOP Secrecy Outage Probability
TAS Transmit Antenna Selection
TDMA Time Division Multiple Access
UAVC Unmanned Aerial Vehicle Communication
UMTS Universal Mobile Telecommunication Systems
URLLC Ultra-Reliable Low Latency Communication
vii
List of Figures
Figure Title Page
No
11 Usage of wireless sensor network and UAV in the
hazardous disaster control
6
12 UAV network applications types with security services
architecture
8
13 UAV-assisted heterogeneous network architecture 12
14 Security problems in the UAV 15
15 Comparative analysis of NOMA vrsquos OMA 18
21 Vehicular communication NOMA system 28
22 RS-NOMA against an external eavesdropper 31
31 Downlink NOMA network 44
32 Uplink NOMA network 46
33 Multi-two user architecture of NOMA system 49
34 Flow Diagram of the proposed system 50
35 Near and Far User 51
41 Impact on Sop with increase distance between BS and user U2 60
42 Impact on Sop with increase distance between BS and user U2 61
43 Feasible pairing t Vs pair OP 61
44 Infeasible pairing t Vs pair OP 62
45 Secrecy outage probability 63
46 Pair outage probability 63
47 SNR versus Strictly positive secrecy rate 64
48 Power radiated by per MMBs antenna 64
viii
List of Tables
Table Title Page
No
11 Physical layer hazards and measures in UAV wireless
communication network
13
21 Comparative analysis 33
31 List of parameters59 54
41 Simulation parameters 59
ix
Table of Content
Sr
No
Title Page
No
I Abstract I
II Acknowledgment II
III List of Abbreviation III
IV List of Figures Iv
V List of tables V
1 Introduction 1
11 Modern technology and its needs 1
111 Long term evolution of 4G network 2
112 Migration from 4G LTE to 5G for UAV communication 3
12 UAV assisted communication in heterogenous sensor network 5
121 Introduction to UAV Communication network 7
122 Tyews of UAVs 8
1221 UAVs as flying BSs 8
1222 UAVs as aerial UBs 10
13 Unmanned aerial vehicle for 5G network 11
14 Physical layer insecurity in UAV communication network 12
141 Principles of security 13
15 Non-Orthogonal Multiple Access (NOMA) system secured
communication
16
151 Comparison of NOMA Vs OMA 16
1511 Spectral throughput and efficiency 17
1512 User fairness and higher lately 17
1513 Compatibility 17
16 Problem identification 18
17 Motivation 19
18 Aim and objective of the research 20
19 Thesis organization 21
2 Literature review 23
x
21 Integration of UAV Networks for 5G and B5G communication 23
22 UAV-NOMA in physical layer security enhancement 26
23 Research methodology 38
24 Summary 39
3 System model for NOMA-UAV communication 41
31 NOMA -UAV system secured communication for 5G 41
311 The basic scheme of NOMA 41
312 Downlink of NOMA 44
313 Uplink of NOMA 46
314 Comparison of NOMA and OMA 47
32 PLS performance metrics in NOMA -UAV communication 47
321 SOP and OP - two user and multi-user NOMA system 48
322 System Model 48
323 Partially Observable Markov Decision Process-POMDP 50
324 Problem formulation 52
33 Performance Analysis Improving PLS Insecurity of NOMA
System
53
331 The pair OP calculation 53
332 Pseudo-code for the proposed algorithm 55
34 Summary 57
4 Result and discussion 58
41 Performance measure of secured NOMA-UAV communication
model
58
42 Numerical result and discussion 59
421 Feasible amp Infeasible pairing of trusted amp untrusted
users
60
422 The secrecy outage probability and pair outage
probability
62
423 SNR versus strictly positive secrecy rate 63
424 Power radiated by per MMBs antenna
64
43 Conclusion and scope of future work 65
431 Conclusion 65
432 Future scope 66
xi
5 References 67
8
Publications 78
1
CHAPTER -1
INTRODUCTION
11 Modern technology and its needs
Mobile technology has undergone various generational shifts transforming the
cellular framework into a worldwide set of interconnected networks In recent days
the fifth generation (5G) has delivered voice as well as video streaming It has a
very complex range of networking services for more than nine billion users and also
billions of devices that will be connected (Hu 2016) However 5G offers a new
outlet for reflection It involves a radial network architecture for the installation of
communication-type machines 5G network can also include powerful support
applications with widely varying operating parameters 5G is a blend of network
technologies that have been developed The new 5G technology will be able to
exchange information anywhere every time for the benefit of people enterprise
and society and technical environments using a restricted access bandwidth to
carry data Now it is more than a modern series of technologies and as opposed to
previous generations would entail tremendous infrastructure or machinery
upgrades This technology aims to expand on the advances that telecommunications
systems have already achieved The projected standards of efficiency that
technologies would need to resolve are
bull Five times reduce end-end latency
bull Ten to a hundred times the higher complex rate of user data
bull Battery life is ten times longer
bull 10 to 100 times higher number of connected devices
In this research work the UAV-assisted communication over the 5G network has
been proposed with enhanced physical layer security aspects NOMA has been
proposed as the reference framework architecture for UAV communication as one
of the recent popular 5G techniques Along with the advantage of suitability in UAV
communication network NOMA has the disadvantage of insecurity in the physical
layer Here the migration of Long Term Evolution (LTE) to advanced physical layer
2
security for Unmanned Aerial Vehicle communication (UAV) over 5G network has
been proposed and also improve the insecurity of Non-Orthogonal Multiple Access
(NOMA) System We will discuss in the further chapter the proposed work This
chapter describes the introduction and basic concepts of the 5G networks with
methodology techniques and types It states the problem identification motivation
and further aim and objective of this work
111 Long Term Evolution of 4G Network
LTE is customary for 4G wireless broadband trends that provide improved network
capability and gives mobile device users speed It offers high peak data transform
rates in the range of 100 Mbps and 30 Mbps downstream and upstream
respectively It provides a capacity of scalable bandwidth mitigated latency and
backward compatibility with the previous Global System for Mobile
Communications (GSM) and Universal Mobile Telecommunication Systems
(UMTS) technology
The fourth development of cellular networks (4G) has already been developed to
meet the standards of the 3G and 2G families Every 10th year a new mobile
generation claimed to be familiarized with the first 1G system in 1981 tracked by
the 2G system that went on to roll out in 1992 and 3G launched in 2001 growth in
the year 2002 of 4G networks The actual new revolution began in December 1998
with the 3rd Generation Partnership Project (3GPP) With high-quality video and
images 3G networks are designed for multimedia networking with them Peoples
communication can also be enhanced and connectivity to public and private
network information and resources has improved with higher frequencies and new
flexible communication features third-party device applications
With the start of LTE-Advanced several vital demands and improvements are
beginning to emerge Various importance purposed for LTE-Advanced can be
exemplified as follows (Abed)
bull Provides spectrum output with LTE delivered more than three times
bull Spectrum can help scalable bandwidth and convergence of the spectrum
where it is necessary to use a non-contiguous range
3
bull Provides uplink and downlink spectrum output that varies between
15bpsHz and 30bpsHz
bull The edge throughput must be twice that of the user cell in LTE
bull From idle status to connected status the communication latency scenario is
smaller than 50msec and less than 5msec for direct packet transfer
bull Any users total throughput must be three times that of LTE
bull LTE advancement will provide 3GPP as well as LTE compatibility via inter
networking
bull The mobility conditions that are used in LTE are identical
The latest LTE advanced requirements are not yet included in device
specifications there are high-level purposes Before it is fixed in the specifications
and needs to be tested much effort remains to be approved
112 Migration from 4G LTE to 5G for UAV communication
The productive implementation of a UAV communication network in 4G and the
upcoming wireless network is included in identifying combined solutions to test
the correlation with both multitudes and also energy-efficient transmission Then
the process of the UAV-BS to optimize coverage and power It is stated that the
energy efficiency of the UAV-aided communication system is needed Efficient
energy utilization contributes to increased air time in the contact system and
increased joulesbits at a provided energy level Also aerial cell coverage and
ability may be because of various parameters such as antenna gains transmission
strength radio access technology UAV altitude and deployment environment
4G is the fourth generation of network infrastructure technologies to replace 3G and
in addition to the popular 3G4G methods Code Division Multiple Access
(CDMA) Time Division Multiple Access (TDMA) and Orthogonal Frequency
Division Multiple Access (OFDMA) Researchers are designing the latest Non-
Orthogonal Multiple Access (NOMA) technologies to be used because of their
capability to improve the performance of communication networks Non-
4
orthogonality-based device designs have recently been developed for use in
communication networks and drawn considerable interest from researchers
Henceforth Multiple Access (MA) methods can be sub-divided as OMA and
NOMA Each user may utilize orthogonal communication resources to determine
multiple access interference inside a frequency band code and time slot in OMA
Its methods such as First generation (1G)- FDMA 2G -TDMA 3G -CDMA and
4G - OFDMA have been used in previous network generations In NOMA by
producing a higher spectral efficiency however enabling some amount of multiple
entree intrusion in receivers and multiple users may use non-orthogonal resources
simultaneously Recently the credibility of NOMA as a solution to the problems of
the next generation of wireless networks has been increased Compared with OMA
technologies NOMA has been described to improve spectral quality be well-
adjusted with air connectivity and can provide accommodations for multiple
strategies at the same time of frequency Therefore enabling excellent progress to
massively correlated devices
In particular NOMA also affects mitigating interference by using OFDMA as an
orthogonal method or through offering a standard intra-cluster access beam across
multiple users and inter-cluster access in NOMA Recent studies have concentrated
primarily on the provision of Air to Ground (A2G) connectivity services through
optimization of a different point of view
The output of the UAV-based communication network was discussed in the Device
to Device (D2D) implementation setup The proposed system hypothesized
interference caused through D2D network nodes deprived of acknowledging the
occurrence of global BS Also several studies addressed the efficiency of NOMA
It permitted the deployment of fixed-wing to assist coverage in-ground user located
outer location of offloaded BS
NOMA systems are divided into two categories namely code domain and power
domain multiplexing In the power domain user accounts are allocated to different
power coefficients as per their channel complaint to reach optimal device
efficiency Multiple user signals are applied to the side of the sender Then on the
received signal Successive Interference Cancellation (SIC) is implemented to
decipher signals in sequential order until the predicted signal is achieved offering
5
a good trade-off between efficiency of the system and user fairness Different code
domain multiplexing is Sparse Code Multiple Access (SCMA) Low-Density
Spreading (LDS) and Multi-User Mutual Access (MUSA) Compared to power and
code domain multiplexing there are alternate NOMA techniques such as Bit
Division Multiplexing (BDM) and Pattern Division Multiplexing Control (PDMA)
However this multiplexing is capable of improving the efficacy of spectral It
requires a large transfer of bandwidth which is not appropriate for new methods
But on the other side the power domain has direct execution since there is no need
for significant improvements to the current networks It also does not necessitate
bandwidth to increase spectral efficiency In this chapter the main emphasis
depends on the power domain NOMA While OMA strategies can produce the best
results also with necessary receivers due to no mutual intervention among users in
an optimal situation they cannot even resolve increasing problems due to growing
demands on connectivity growth and even beyond
12 UAV assisted communication in heterogeneous sensor network
Wireless communications had created a golden chance for urban and rural
territories The LTE (Long term evolution) and LTE-A (Long term evolution
Advance) had offered the service (with QoS) for all customers through wireless
The traffic properties in the machine type communications (MTC) and the
accumulation of the MI (Mobile Internet) had made the difficulty of implementing
the cellular communication networks Installing base stations was impractical in the
urban areas due to its cost To overcome this issue the UAV suggested that it
contains the merits of compatibility and high battery life and is affordable Most of
the devices like the sensor nodes and professional cameras had been used in UAV-
assisted networks Here the UAV-assisted floating relay (FR) was launched in the
cellular communication networks UAVs were implemented more with WSN
(wireless sensor networks) The base stations were adopted with the UAV So the
MI and MTC traffic challenges were controlled (Yue Li amp Cai 2017)
UAV-assisted Heterogeneous networks had implemented in vast practical
applications UAV helped heterogeneous networks were applied in the military
department In the military the UAV had examined and surveyed the opposing
6
countryrsquos activities for security The UAV-based heterogeneous networks were
used in the military sectors where a novel authentication scheme was introduced
As The one-to-one communication via WSN was considered as secured
communication WSN had the disadvantage of consuming power The
authentication was implemented in the tool of Automated Validation
of Internet Security Protocols and Applications (AVISPA) in which the expression
had been written in the High-Level Protocol Specification Language (HLPSL)
programming language The authentication had evaluated between the user and the
base station Similarly the authentication between the user and the UAV was
calibrated The citizen and economic safety are predicted and conserved through
reliable communication in the military by obtaining foes exploration information
The faithful secured communication was confirmed using AVISPA (Rashid et al
2019)
Figure 11 Usage of wireless sensor network and UAV in the hazardous
disaster control
The integration of the wireless sensor networks and the unmanned aerial vehicle
UAV was analyzed and applied to manage the natural disaster illustrated in Figure
11 The aircraft can prevent the fire spreading drop sensors the temperature map
and biodiversity map by sensors the wildfire can easily route The wild animals can
7
be tracked and the dynamic data of moving animals can be gathered by WSNs The
biologists can fix the sensor in the animals collar the radiation that positively
affects humans can be observed in affected areas The WSNs help to prevent heart
attack of a person by monitoring heart rate The state of health can be known
through a message alarm using a GPRS system
The cooperative networks of WSN and UAV were implemented in the military
sector for the advantageous feature The UAV was providing good connections
overlapping and overall data rate The conventional UAV method aided sensor
networks concentrated only on the single tasks of monitoring accumulating
information and localization The multi-UAV had not been implemented in the
sensor networks The animal colony perception technique was utilized for
scheduling the resourced and the target assignment Functions of multi-data were
used for localization by the target recognition method (Gu Su et al 2018)
The Physical Layer Security (PLS) was achieved through 5G technologies delicate
coding for the PLS dense MIMO multi-input multi-output mm-Wave frequency
band using heterogeneous sensor networks NOMA and full-duplex mode of
communication IoT and Machine-type communications (MTC) emerged in the 5G
systems (Wu et al 2018)
121 Introduction to UAV communication network
The usage of the UAV will develop more in the next era These pre-programmed
aircraft are intended for applications in several civil settings as well as industrial
visualization agriculture rescue and search and then receiving of scientific data
These devices are called the unsuccessful inaccuracy of drones which must be
incorporated into the system of national airspace as well as worldwide The usage
of UAVs in the neutral form is always secure It has a direct inference for the control
and a payload communication system that is utilized to function effectively
Similarly surveillance and navigation operations must be made more accurate and
consistent Due to these critical factors many kinds of research in a UAV testing
development and standardization difficulties are undergone through industries
education and governments
8
Even though civil aircraft had been operating for many years yet UAV offers new
consequences in terms of various flight profiles For example high dynamic
maneuvers and low elevation flights need bandwidth video and different ground
site characteristics namely clutter locations and elevation antennas which are low
This chapter explains the core topic of the proposed work The migration of LTE
4G towards the advanced one of the physical layers for UAV communication It has
higher mobility and lower expense identified in a broad range of applications
122 Types of UAVs
The UAVs have a two-network application with security services such as UAVs as
Flying Base Stations (BSs) and UAVs as Aerial BSs in the presence of
eavesdroppers
(a) UAVs as Flying BSs (b) UAVs as Aerial mobile UEs
Figure 12 UAV network applications types with security services
architecture
1221 UAVs as flying BSs
The required infrastructure can be destroyed in natural disasters particularly
tsunamis earthquakes and snowstorms and the requisite emergency data traffic
cause both overloading and congestion of neighboring mm-Wave (Zeng et al
2016) A capable explanation is to rapidly introduce low-altitude UAVs as flying
9
BSs in such a network breakdown to improve the communication infrastructure to
mitigate cell congestion or site failure thus creating a small aerial cell
In this situation wireless communications can occur in an ad-hoc manner with
UAVs to UEs UAVs to UAVs As highlighted in Figure-12 (a) and control
stations of UAVs to ground It will increase capability dramatically and enlarge the
target of wireless networks in provisional measures as it is possible to create LoS
communication links among UAVs and UEs supported on the ground Yet form an
operating aerial cell system to monitor ground segments of UEs mobility which is
more stable to minimize sporadic connectivity on the other side
Also this can be expanded to allow several UAVs-BSs to be deployed to increase
the exposure area for supporting a wide range of UEs A network period various
UAVs-BSs is entirely independent A new paradigm was introduced through
collaboration between UAVs-BSs to extend the feasibility for a single UAV from
either a stand-alone active sensor to a wireless network over the next generation
There is a growing concern about the privacy problem in tandem with the brief
introduction of this network Wireless protection is the central issue of the
communication level wherever eavesdropping subsidizes for deliberately listening
to a source of secret information which harms the extensive placement of UAV-
BSs
A UAV-BSs is to mount several antennas in the UAV-BSs the benefits of multi-
antenna innovations geographical degree of freedom that offers an ability for UAV-
BSs to transmit eavesdropping airborne beams
Notice that in UAV systems multi-antenna technology can be technically applied
while directly modifying the separation of the antennas The existing system has
shown that transmitted beam forming models can significantly boost the
confidentiality efficiency of wiretap channels for multiple antenna transmitters
Noise may be inserted with the signal to substantially degrade the acknowledged
SINR at the eavesdroppers to prevent the information overflow
10
1222 UAVs as aerial UEs
This has already been demonstrated by reaping the benefits of Wi-Fi and LTE
technologies through field trials (Van der Bergh et al 2016) UAV-UEs typically
get their tasks for a variety of convincing IoT applications mainly in air freight
services like the google wing project Unlike conventional land base package
delivery but UAV delivery has distinctive merits such as
bull Acceleration of land transport as UAVs are not liable to road jams
bull Connection to areas that are difficult to reach
bull Decreasing the use of capital about workforce and electricity
UAV distribution is significantly dependent on having reliable and secure wireless
communication among UAVs and ground BSs especially if the UAV needs control
outside LoS the UAV-UEs are used which can develop LoS connectivity to cellular
BSs The UAV-UEs on the one hand provides high-speed access to data as it can
fly continuously in either direction On the other hand the installation of UAV-UEs
can lead to significant interference with the ground BSs in the execution of their
missions
A wide-scale installation of UAV-UEs is only feasible for this reason if the issues
of interference management are tackled It is widely known that interference
negatively affects wireless networks As highlighted in Figure-12 (b) indeed aerial
and ground UEs are served through a cellular network with a possible eavesdropper
that tries to intercept the message intended for permissible basic UEs
A cost-effective approach is to be used for coordination among ground BS and
UAVs to enhance secure transmission which is part of the UAVs acting as friendly
transmitters to degrade the wiretapping channels efficiency and thus enhance
secrecy efficiency A UAV acting as a mobile jammer can dramatically and
dynamically change its position as near as possible to the earth eavesdropper and
distribute them by sending the radio signals whereas strong LOS connection
characteristics are a beneficial feature with less earthly fading and shadowing
impairment
11
13 Unmanned Aerial Vehicle for 5G Networks
UAVs have technologically advanced as a revolutionary movement in delivering
pervasive connectivity from either the platforms of the sky as aerial
communication particularly for temporary User Equipment (UEs) (B Li et al
2019) Due to fully controllable UAV flexibility through miniaturization as well as
continuous cost reduction low-altitude UAVs are rapid and flexible designed for
operation and reconfiguration They are probable to have higher Line-of-Sight
(LoS) ties to ground UEs
A broad range of applications like inspection of infrastructure precision farming
and disaster area monitoring is becoming accessible in this aspect Moreover
further projects have also been set up to employ aerial platforms for broadband
access to distant elements such as the Google Loon and the Facebook Drone Project
to mention Highly populated UEs are desperate for broadband wireless
communications with the coming 5G period and network providers are supposed
to maintain numerous networks with high demands for wireless data like
multimedia streaming and also video downloads The relentless growth in the
amount of traffic of mobile networks puts a burden on operators in the form of
higher capital and operational expenditure Deploying small cell networks is an
intuitive alternative to outsource cellular traffic
Although in unforeseen or temporary events as mobile environments are
complicated volatile and heterogeneous the implementation of terrestrial
infrastructures is difficult The accessibility of aerial access points to enable
extensive complex connections is one possible solution However in unforeseen or
temporary events as mobile environments are complicated volatile and
heterogeneous the implementation of terrestrial infrastructures is difficult The
accessibility of aerial access points to enable extensive complex connections is one
possible solution UAV communication performance benefits from the simplicity
of the compact transceiver and progressive control methods that obtain broad
exposure and set up internet networks
12
Figure 13 UAV-assisted heterogeneous network architecture
The above Figure 13 is depicted to build flexibility of the network with enhanced
ability and elasticity It is a good network that offers security endowment This is
due to the transmitting information to UAV communication which is tapped
through ground unauthorized user and is known as an eavesdropper
Here through eavesdropper based on the upper layer cryptographic techniques
wireless communication in contradiction of unauthorized access has been protected
However it is very tough to achieve because of key management as well as more
computational difficulties in developing network architecture PLS affects the
characteristics of intrinsic wireless networks as a fascinating preparation such as
interference noise fading loss collecting signal characteristics in malicious
eavesdroppers and techniques of signal processing
14 Physical Layer Insecurity in UAV communication network
Jamming is either a well-defined WSN attack on a physical layer It disrupts the
radio waves being used by nodes of the network The attacker successively
expresses the denial of the simple MAC protocol over the wireless network The
impressive network can be disrupted at which a single frequency is being used
13
throughout a network (Modares et al 2011) In addition jamming can increase
energy consumption in the node by inserting impudent packets The receiver nodes
will also generate resources when receiving the packets In (Jeon 2006) four
different terms of jamming attacks that an intruder could use to interrupt the
wireless network activity Tampering is yet another physical layer assault
Table 11 Physical layer hazards and measures in UAV wireless
communication network
(Kumar et al 2014)
Hazard Security measures
Jamming Channel blacklisting and hopping
Interference Channel hopping and blacklisting
Tampering Security and key modification
Sybil Physical security of the system
Table 11 describes physical layer hazards and their security measures in WSN
which tampering and jamming are considered as the main attack in the physical
layer in WSN
141 Principles of security
The security requirement of UAV communication network is as follows (Kumar et
al 2014)
Confidentiality Ensure that only the approved sensor nodes could get the contents
of the texts
bull Authentication Ensure that the data is introduced from the sound source
bull Integrity Ensure that every received text has not been modified to be sent
by unauthorized users
14
bull Freshness Make confirm that no old information has been reiterated
bull Availability services are feasible at any time through WSN or by a single
node
The standard attacks of the physical layer are as follows (Sastry et al
2013)
bull Jamming The transmission of the radio signal can interfere only with radio
frequencies used through WSN which is known as jamming As the
capacity grows it may influence more significant portions of the network
by transmitting other radio signals The opponent will use a few nodes to
occupy the entire channel This state is called physical layer jamming which
results in a denial of service In this scenario the opponent will not be
permitted to have any knowledge but will be capable of preventing
communication to any nodes
bull Tampering Often the nodes tampered through an opponent This mode is
called tempering Here the attackers can destroy exchange and
electronically confront nodes to obtain information from counter measures
towards jamming that have been planned as spread as well as frequency
hopping
bull A security mechanism is used in WSN to track avoid and recover from
security attacks A wide range of security schemes can be devised to counter
malicious threats which can be classified as high and low levels
bull Secrecy and Authentication Most network sensor applications need
protection from eavesdropping packet alteration and injection Early
networks are used for connection layer cryptography as this approach offers
the easiest deployment of network cryptographic solutions
bull Privacy Like all other conventional networks the radio networks have also
brought secret issues to allow Initially sensor networks are implemented
for legitimate purposes and can eventually be used unexpectedly
Knowledge of active sensor nodes as well as the acquisition of data is
exceptionally crucial
15
bull Critical launch and trust setup The primary prerequisite for setting up a
network is the development of keys (cryptography) Sensor devices
typically have minimal computing capacity and public cryptographic
primitives are too difficult to adopt Critical establishment and strategies
need to be scaled to network with thousands of nodes
bull Secure routing Routing as well as data forwarding is a problem that
confronts to facilitate communication in networks Regrettably the latest
protocols encounter a variety of security flaws
bull Robustness of communication Does An opponent challenges to interrupt
the operation of the network
Figure 14 Security problems in the UAV
Figure 14 illustrated the security difficulties in a UAV The physical layer security
in the UAV wireless networks was examined The UAV had affected by both active
eavesdropper and passive eavesdropper This paper proposed the trajectory design
and cooperative UAV for constraining the eavesdropper NOMA MIMO mm-
Wave frequency band in UAV would cause better spectral efficiency and security
(Xiaofang Sun et al 2019)
UAV implementation of the 5G communication was considered advantageous The
UAV was assumed as the novel wireless network technique for the territory users
and their base stations The UAV had resulted in high altitude So the UAV had
16
considered a superior line of sight At the same time the possibility of security
problems was raised in a UAV The secrecy in the existence of eavesdropper the
jammer in the ground was performed using the UAV UAV aided territory security
was proposed The UAV was involved in inspecting the eavesdropper and hazard
jammers on the base stations territory UAV had targeted the global position system
spoofing for assisting the authentic users and performed the role of an artificial
eavesdropper for excluding the eavesdropper and jammers in the ground (H-M
Wang et al 2019)
15 Non-Orthogonal Multiple Access (NOMA) System Secured
Communication
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
151 Comparison of NOMA Vs OMA
Comparison of the NOMA and OMA can be discussed as follows
17
1511 Spectral throughput and efficiency
In OMA a resource is allotted to the distinct user whether it is good or bad in a
channel scenario like OFDMA Thus the whole process moves from less
throughput and performance
While the same frequency is allotted to the multiple-use at the same time with good
or bad channel operation in NOMA here the weak user gets the allocated for the
resources which the strong user can also use it And the interference can be reduced
by the SIC process on the receptor side of the user Consequently the probability
with the increased spectral efficiency as well the high throughput will be
maximized
1512 User fairness and higher lately
A user of fair channel complaints has higher precedence to be served in OMA In
contrast a user with a poor channel complaint is to remain activity which causes
the issue of user fairness and higher latency Yet OMA cannot assist colossal
connectivity Whereas NOMA helps multiple users with various channel
procedures and offers increased fairness massive connectivity and lower latency
1513 Compatibility
NOMA has compatibility with the current and upcoming scenario meanwhile no
need for necessary changes to the previous methods As an instance NOMA has
been bought up in the 3G Partnership Project LTE Advanced (3GPP LTE) Though
NOMA contains many characteristics that can assist the upcoming generations and
it has some restrictions that can be explored with its full benefits Those restrictions
are as follows
bull Each user has to decrypt the signals of other users until decrypted their
signal the complexity of the receiver would be strengthened in NOMA as
opposed to OMA which creates a long pause
bull Also data on channel quality for all users should be returned to the BS but
this results in substantial CSI input overhead Furthermore if any issues
arise to any consumer during the SIC process the likelihood of consecutive
decrypting errors will be improved
18
Figure 15 Comparative analysis of NOMA vrsquos OMA
As an outcome the number of users is reduced to ignore the spread of such
debugging Another aim of restricting the number of users is that there must be
substantial variations in channel revenues between users with different channel
grievances to provide network reliability
16 Problem Identification
The NOMA-based architectures main feature is to configure trusted and untrusted
users when more than one eavesdropper is present in the dense setting of todayrsquos
and future sophisticated wireless communication networks This research aims to
examine the security efficiency suggested for mission-critical applications in the
NOMA-based UAV communication network The proposed system underpins two
user NOMA frameworks The possibility of paring both users was explored with
PHY performance measures in mind Outage probability (OP) and Secrecy Outage
Probability (SOP) Dynamic Optimization Method Programming (DP) and Partially
Observable Markov Decision Process (POMDP) optimization have also been
analyzed to explore the feasibility of achieving an outage-optimal output for the
pair under the heavy users secrecy outage restriction The optimized theoretical
findings are applied to the multiuser scenario The identifications were tested
through a computer model in which POMDP has shown substantial progress over
the dynamic optimization method to program
19
17 Motivation
Unmanned aerial vehicle (UAV) wireless communications have experienced an
upsurge of interest in both military and civilian applications due to its high
mobility low cost on-demand deployment and inherent line-of-sight air-to-ground
channels However these benefits also make UAV wireless communication
systems vulnerable to malicious eavesdropping attacks
Despite the promising gains brought by UAVs the open nature of air-to-ground
wireless channels makes secure information transfer a challenging issue
specifically on the one hand information signals transmitted over wireless LoS
channels are likely to be intercepted by some undesired receivers which lead to a
risk of information leakage On the other hand wireless UAV transceivers are
vulnerable to malicious jamming attacks Hence security plays an extremely
important role in UAV wireless communications Unfortunately traditional
encryption techniques require high computational complexity leading to a large
amount of energy consumption which may not be suitable for UAV systems As an
alternative physical layer security is computationally efficient and effective in
safeguarding wireless communication networks via exploiting the inherent
randomness of wireless channels As a result various physical layer techniques
have been proposed in the literature for guaranteeing communication security
NOMA is viewed as a promising technique to provide superior spectral efficiency
by multiplexing information signals at different power levels [13] Hence it is
expected that NOMA can bring additional rate and robustness to enhance the
achievable rate in UAV physical layer security communications Consider a
scenario where a UAV acts as a relay to facilitate data delivery to two receivers
with different security clearance levels within a maximum cruising duration T The
receiver with a lower security clearance level and a higher potential with an
eavesdropper Since it has a strong motivation in intercepting signals intended for
a receiver with a higher security clearance Then when the eavesdropper suffers
from a bad channel condition NOMA is adopted to forward both confidential and
public information simultaneously Otherwise UAV only broadcasts the public
information for security issues The mode selection between NOMA and unicast is
20
chosen based on the results of the proposed resource allocation optimization In
particular for maximizing the spectral efficiency one needs to jointly optimize the
transmission scheme resource allocation and UAVrsquos trajectory However the
coupled optimization variables generally result in non-convex optimization
problems which are difficult to solve optimally As an alternative an iterative
suboptimal algorithm based on successive convex approximation can be employed
to facilitate a computationally efficient joint design We have discussed that the
NOMA scheme always outperforms OMA in all the considered scenarios which
demonstrates the spectral efficiency advantage brought by NOMA in striking a
balance between public data rate and confidential data rate
The main motive of this research is to enhance the inherently insecure PHY layer
of the NOMA-based UAV communication network NOMA-UAV communication
network requires feasible paring between trusted amp untrusted users (attacker) for
cooperative communication mainly in real-time field applications The power
allocation factor need to be optimized as per the trustworthiness of the associated
users (reliable user) and keeping the outage probability minimum for secured and
cooperative communications The pair Outage Probability and the SOP have been
optimized jointly for feasible pairing between BS amp the associated Users
18 Aim and Objective of the Research
The proposed works main objective is to examine the design of a NOMA-based
UAV communication network for enhanced Physical Layer security (PLS)
features Remarkably it is anticipated infrastructures and resources to connect
numerous devices and provide various services Researchers these days
concentrating on ways to design a heterogeneous framework like deployed small
cells air and ground-based deploy multifarious communication methods in 5G
such as millimeter-wave (mm-Wave) device-to-device (D2D) massive multiple-
input multiple-output (MIMO) Cognitive Radio (CR) and so on for improving
spectrum and energy efficiency
As a critical need especially for emergency applications the adoption of NOMA
transmission of UAV communication needs to be improved PLS A new optimal
resource allocation algorithm for some more robust and stable communication in
21
single and multiuser scenarios has been suggested here The PLS in dense
heterogeneous sensor networks has improved by the feasible pairing of trusted and
untrusted users (K Cao 2019 T Zhao 2018) In the instance of untrusted users
dynamic programming and POMDP are subjected to the channel conditions
details optimizing OP and SOP as a restricted parameter accompanied by resource
allocation (Davis 2018 L Hou 2018)
The main aim of the proposed research work areas
bull To analyze the underlying NOMA UAV communication framework with
enhanced Physical Layer security (PLS) implications for particular quest
applications
bull To examine the potential pairing of trusted and untrusted users in the
NOMA-based UAV contact network with two users and multiuser scenarios
for certain channel conditions called Channel State Information (CSI)
bull To maximize resource allocation among trusted and untrusted users by
pairing OP and Secret Outage Probability (SOP) as performance measures
with the POMDP optimization method
bull To evaluate POMDP and dynamic programming resource allocation with
two users and multiple users for both protected NOMA-based UAV
communication network scenarios
19 Thesis Organization
Chapter 1 Provides the introduction and basic concept of the proposed work with
the problem identification motivation and aim and objective of the proposed work
Here we described LTE 4G and its advanced techniques than about the NOMA and
its basic scheme UAV concepts represent their types and basic working strategy
Chapter 2 Provides a survey of the existing technologies which is related to the
proposed work The NOMA transmission schemes Merits and De-merits related
to security UAV assisted communication in heterogeneous sensor networks UAV
networks of 5G and beyond communications has been explained then about UAV-
NOMA PHY secured communication techniques as well
22
Chapter 3 Describes the proposed work of improvement of physical layer
insecurity of the NOMA The overflow and its performance measures with
simulated output have been defined in this chapter
Chapter 4 Describes Migrations proposed work from 4G LTE to advanced PHY
techniques for UAV communication The overflow and its performance measures
with simulated output have been explained in this chapter Concludes and explains
the proposed work with its outcome and the future scope of the proposed work
23
CHAPTER 2
LITERATURE REVIEW
21 Integration of UAV Networks for 5G and B5G communication
5G and B5G had been anticipated to give a unique connection among universal
users The UAV had been emerged for its advantage of wireless network and
relaying high data rate The UAV in the 5G and B5G was introduced and 5G and
B5G were updated with the new concept of Space-Air-Ground Integrated Networks
(SAGIN) Three layers were established named physical network communication
link and evaluation Besides the usage among the dense population IoT was
applied in satellite communication In which the IoT had provided the uninterrupted
service with high data rate communication The scope for flying UAVs had been
created for enhancing the number of mobile users with IoT (Ali et al 2018)
5G and B5G had projected the UAV as the vital constituent One to multiple point
transmission can be possibly advance in 5G and B5G The structural design of the
upcoming UAV (multi-tier drones) was driven by the routine of different structures
like the maximum functioning altitude communication overlap coverage and
determination The UAVs practicability (multi-tier drones) among conventional
UAVs (single-tier drones) is scrutinized in that perspective By ascertaining the
circumstances UAV (multi-tier drones) could supplement the older terrestrial
networks with RF Initially UAV (multi-tier drones) and drone-aided wireless
networks were related to finding the tasks The modified UAV (multi-tier drones)
and the drone-administered wireless networks were analyzed The enactments of
UAV (multi-tier drones) were scrutinized in the contest of spectral efficiency in the
downlink networks Their effect had exhibited the detailed network parameters The
UAV distribution (multi-tier drones) was considered advantageous for the spectral
efficiency from the downlink transmission over traditional terrestrial wireless
networks (Sekander et al 2018)
The growth of 5G and B5G wireless networks prominently hang on the
incorporation of the terrestrial and aerial systems in innovative heterogeneous
network architecture They had advanced a creative and tangible multiple UAV
24
made up of cluster UAV ndash base stations and Poisson point process with UAV and
mm-Wave frequency band Ground user equipment and UAV had exhibited as the
Poisson cluster process and then spread around the public cluster in the distinctive
cluster In particular the scrutiny was accompanied by the accumulation of extra
tiers Extra tiers were made up of multi-cluster UAV base stations and single ground
user base stations in the characteristic cluster Four-tier network systems were
designed correspondingly from the subdivision of the above-said base stations
Two-tier and four-tier association patterns were built for discovering the
involvement of the cluster networks The coverage probability for the downlink and
network throughput was derived (Ji et al 2020) The numerous subordinate title
role of the multifaceted communication systems was performed by the UAVs The
UAV was acted as the air relay in the maintenance of ground networks The UAVs
were used in the countryside hilly zones whereas the communication was
inadequate The author anticipated resolving the viable communication difficulty in
5G and B5G vehicular ad-hoc The associate communication pattern established on
the smart UAVs was planned given the crisis condition of the car ad-hoc The smart
UAVs were supporting the vehicular ad-hoc strong communication in real
situations Above and beyond its actual characteristics of the vehicular ad-hoc were
needed to be endangered to avoid the prohibited features from attaining and
exhausting for law-breaking practices Innovative UAV with a secret authentication
key arrangement was recommended in the 5G and B5G vehicular ad-hoc Because
of supporting efficiency the vehicle network which guaranteed communication
confidentiality was not negotiated The suggested pattern was confirmed to be
unaffected by numerous outbreaks by exploiting the broadly applied natural or
random ROR scheme
Furthermore the projected scheme had well calibrated the communication
overhead from the performance estimation (J Zhang et al 2020) The UANs had
obtained a phenomenal role in the research area the emergent sector of aerial
robotics The parcel transport organization monitoring occurrence shooting
surveillance and tracing were the metropolises general operations utilizing the
UAV Various domains would use 5G and B5G to improve UAV networks UAV
ecological unit was advantageous in present 5G and B5G mobile communications
For UAVs intrinsic features they were concerned for flexible movement of three-
25
dimensional space independent actions and smart locations These devices were
provided with extensive scope in cellular networks The author proposed an in-
depth assessment of implementing cooperation between UAV and 5G and B5G In
which UAV had been assimilated as a novel user equipment of aerial in present
mobile communications The UAV had implemented the duty of flying users within
the network coverage named the cellular-connected UAVs in this amalgamation
The author showed a broad examination of the incorporation tasks with 5G and
B5G novelties Continued efforts in the prototyping and validation of mobile
communication UAVs were conducted using the ground trial The paper had
focused on the current growth in 3GPP The social-economic had not been taken
into account which was considered disadvantageous (Mishra amp Natalizio 2020)
The UAV was anticipated as the significant constituent in the 5G and B5G wireless
networks 5G enables the UAV to be used in broadcasting and end-to-end
communications using the small UAV They needed a devoted and endangered
aerial spectrum in the aircraft cargo by letting small UAVs run in space in
supervisory authority The security information was obtained from the link Control
and Non-Payload Communications (CNPC) The security information contained
the regulation of UAV and the line of sight of terrestrial The CNPC application in
the 5G and satellite communication was scrutinized in this paper Payload
communication like mm-Wave networks and UAV were analyzed in this paper The
direction-finding and reconnaissance difficulties were examined UAV
communication systems were scrutinized and the hardware challenges were
discussed (Hosseini et al 2019)
The potential gain from the UAV-assisted data gathering was found in
indiscriminate IoTs The characteristic propagation was represented by utilizing the
complicated channel method (contained small- and large-scale fading) IoTs were
updated in constrain of transmit power (in high) and total energy The multi-antenna
UAV was selected in the IoTs in sequence The virtual MIMO was created by the
communication between UAV and singe antenna IoT in every transmission (W
Feng et al 2018)
The UAV was applied in the aerial coverage surveillance agricultural prediction
constructional areas and power line supervising and blood donation The flight
26
period increment payload capability fast movement and speedy placements were
implied features in the UAV so that the UAV was exploited by the applications of
5G and B5G (Ullah et al 2020)
The UAV was considered a motivation for many emergent usages and reformed
social-economic welfares The wireless networks for the UAV and the base stations
were desired for the UAV function Mobile communications were considered
suitable for finding tracing and regulating the flying UAV The wireless
communications were selected for their features of broad coverage quality of
service and secrecy The wireless communication in the UAV improved
productivity besides the line of sight (G Yang et al 2018)
22 UAV-NOMA in Physical Layer Security enhancement
The NOMA has been applied in the fifth generation (5G) technology The Multicast
Cognitive Radio (MCR) network is implemented using the NOMA and coined as
MCR- MOMA The transmission side is also included with the superimposition
code The decoding was applied at the receiving end So an unknown user is
deduced in their methodology (Meng et al 2020)
The physical layer security for the cooperative NOMA was examined Amplify
and forward decode and forward were taken into consideration for achieving
secure transmission (Chen et al 2018)
The physical layer security of the NOMA was analyzed in the broader network with
varying locality The single and multi-antenna were established in the following
cases The single antenna was taken for an end-to-end connection in a secured
manner And the multi-antenna was used for the connection of base station and
random user Finally achieved security for the multi-antenna on the transmission
side The security of the single antenna was attained by introducing the excluding
area for eliminating eavesdroppers The individual expression of security outage
probability for both single antenna and multi-antenna were derived (Yuanwei Liu
et al 2017)
The secure transmission of NOMA in large-scale applications was investigated
Stochastic Geometry was utilized for placing the eavesdropper and user nodes The
equation for secrecy outage probability was derived and expressed for evaluating
27
secure transmission Security can be improved by expanding the protected zone
(Qin et al 2016)
The power domain NOMA had the disadvantage of decoding data by other
unauthentic users of the same source For reducing unauthentic users the base
station should treat the unauthentic users with different cleaning methods The
secrecy outage probability was investigated for authentic users and unauthentic
users Both users were combined as a pair to the non-uniform distribution of original
and unauthentic users The pair outage probability of genuine users from the secrecy
outage probability restrained NOMA authentic users The derivation for pair outage
probability and the secrecy probability were expressed for calibration The
combined system had been the better security (ElHalawany amp Wu 2018)
The physical layer security was considered problematic in the wireless networks
mainly for keeping the authentic userrsquos data The UAV was acted as the base
station UAV based base station had sent the extensive data to the original users
NOMA with the multi-antenna with mm-Wave frequency band transmission had
enhanced the spectral efficiency The physical layer security was attained by
announcing the space around user locality as the eavesdroppers protected zone
Covering the entire eavesdropper area was considered a resource-consuming way
The shape optimization for the protected location in each UAV base stations
altitudes was introduced The derivations for the secrecy sum rate and the secrecy
outage probability were expressed (Rupasinghe et al 2018)
The vehicular communication system had used cooperative NOMA The secrecy
outage probability was considered in vehicular communication The relay can be
used in both modes (half-duplex and full-duplex) in vehicular communication The
closed derivation for the secrecy outage probability was expressed The security of
the full-duplex NOMA resulted better than that of the half-duplex NOMA The
limitations are that the velocity of the vehicles was not considered Figure 21 is
illustrated the conceptual model of the vehicular communication NOMA system
(Xie et al 2019)
28
Figure 21 Vehicular communication NOMA system
The physical layer security of the uplink NOMA of the large-scale devices was
examined The connection networks had investigated with the approach called
stochastic geometry The new derivation was expressed for the coverage
probability The protected zone restrains eavesdroppers to the authentic users
Efficiency secrecy throughput was examined wiretap channels and the many
original users Constant transmission and variable transmission were collectively
inspected The signal to noise and the movement to interference ratio were derived
drastically (Gomez et al 2017)
The wireless system was executed using Space-Time Block Coding (STBC)
approach in the NOMA of mm-Wave MIMO The technique focused on haphazard
users So the pairing method was introduced mainly for Random Near-Random Far
(RNRF) Here the latent period could be minimized and the RNRF has also been
deduced for the overhead issue The result revealed the systems efficiency with a
proper implementation (Ghavidel et al 2020)
The recent arbitrary beam forming method was proposed in the multiple access
NOMA The pairing had decided to the user places So the evaluation was focused
on the system overhead The result revealed that the proposed work outperformed
29
the existing methods (Aghdam et al 2020) NOMA enhances the reliability of
multi-users transmission The sum rate could be reduced for improving Quality of
Service (QoS) power transmission and signal outage probability The
eavesdropper easily accessed the multi-access systems that cause physical security
during transmission (Z Li et al 2020)
The NOMA had provided spectral efficiency speed transmission of data multiple
networking and less latent period The NOMA utilizes the power domains for
various access Cognitive Radio Networks (CRN) is used to screen illegitimate
users The legitimate users were only permitted in the CRN by the Primary User
Networks (PUN) QoS The cooperative NOMA here implemented with the PUN
and the system performance is enhanced The spectral efficiency can be improved
by the secured transmission The cooperative NOMA was additionally developed
in the CRN with the PLS A new method of cooperative NOMA in the CRN was
examined The PUN technique attains a secure transmission Multiple antennae
were used in this study for reliability and the eavesdropperndashexclusion zone method
is used for better security (B Li et al 2018)
The downlink NOMA for moderate CSI was examined The challenge of the power
domain was rectified by allocating power NOMA The power in NOMA and that
of the OMA was analyzed which resulted in a significantly reduced NOMA (Cui
et al 2016)
Here the users were multiplexed by the power domain So the method was coined
as power domain NOMA The demand arising from the B5G (Beyond 5
Generation) had reached using power domain NOMA Machine learning in the
NOMA was described (Maraqa et al 2020)
The uplink NOMA with the PLS was proposed The uplink NOMA contained a
single base station and multi-users a couple of users combined for NOMA The
known jammer emitted the pseudo-noise to divert the eavesdroppers The study had
suggested the two jammers in the uplink NOMA for secure transmission (N Zhao
et al 2020)
The Intelligent Reflecting Surface (IRS) is designed using downlink NOMA The
multi-access had used the space direction of the beams of closure users The IRS
30
had performed the multi-access for every spatial order by the cell edge users of the
orthogonal beams (Ding amp Poor 2020)
The multi-input single-output NOMA has introduced the technique called Secrecy
Beam Forming (SBF) SBF had utilized the artificial noise for NOMA security
aided users in which the eavesdropperrsquos channels deteriorated The SBFs secure
transmission can be achieved in which high successive interference cancellation is
gained (L Lv et al 2018)
The superposition coding was performed in the transmission pat The successive
interference cancellation was conducted in the receiving position These two
techniques were combined in the novel 5G aided NOMA The basic concepts of
uplink and downlink NOMA were mentioned The dominant condition was
performed in the two user clusters of NOMA The prevailing state had issued the
confirmed spectral efficiency gain in NOMA (Tabassum et al 2016)
The relay scheme in IoT was examined for the secrecy of NOMA This was coined
as relay selection NOMA The base station had transmitted the secret messages to
the two NOMA-aided sensors and eavesdroppers IoT had treated the sensors and
eavesdroppers with different power allocations The expression for certain outage
probability and the strictly positive secure capacity was derived Increasing the
number of the relay would enhance the security in the NOMA-aided IoT The
outage probability for NOMA and OMA were compared The NOMA resulted in
better outage probability in Decode and forward mode (Do et al 2019)
31
Figure 22 RS-NOMA against an external eavesdropper
The NOMA-aided IoT was utilized to fight against the external eavesdropper as
Figure 22 The secured NOMA was proposed The base station sent secret
messages to several authentic destinationsmdashseveral eavesdroppers and unauthentic
users
Nakagami-m fading model was carried out using the multiple antennae in the
channel The security was attained using the max-min transmit antenna selection
scheme Both authentic and unauthentic eavesdroppers were analyzed The closed
derivation for the cumulative distribution of the original user was expressed first
That was compared with the unauthentic user The derivation for the secrecy outage
probability was obtained to identify the level of secrecy performance (Lei et al
2018)
Reconfigurable intelligent surface (RIS) aided NOMA was established for the
secrecy performance The main disadvantage of this model was the chance of using
RIS by the eavesdropper The secret outage probability was derived in this paper
The RIS improved the secrecy of the traditional NOMA The eavesdroppers were
limited from receiving the RIS signal by enhancing the number of intelligent
elements in the RIS A high signal-to-noise ratio was obtained from this experiment
(Liang Yang amp Yuan 2020)
32
The cooperative relaying NOMA was proposed for improving private transmission
in wireless networks Full duplex mode transmitted the jamming signals That
received the required communication at first Secondly the jamming signal
emission was sent by the base station The power allocation for the jamming signal
and information signal was decided on the eavesdropper channel state information
The eavesdropper was jammed by the signal from the first phase with maximum
power Second the derivation of the secrecy outage probability was expressed by
static eavesdropper CSI (Y Cao et al 2020)
The NOMA achieved spectral efficiency and secrecy The security of the multi-
NOMA users was obtained by the successive interference cancellation (SIC)
decoding in the receiving node The conservation of the untrusted NOMA was
concentrated in this study The security can be confirmed by the properly secured
decode processing and allocating power The decoding scheme was implemented
for aiding NOMA users The decoding was performed for enhancing the sum-rate
(Thapar et al 2020) The cognitive radio network in NOMA with the external
eavesdropper was proposed (Mehr et al 2020)
The cooperative NOMA was used in the field of energy harvesting communication
The novel relaying technique was introduced for achieving secrecy The secrecy
outage probability was derived and the derivation was expressed for the three
conditions The first condition was the derivation of CSI with a passive
eavesdropper The second condition was the derivation of CSI with the unauthentic
eavesdropper The third condition was the derivation obtained from the multi-relay
nodes The increased SNR resulted in high security The increase in the number of
users deduced security This was considered a disadvantage (Salem et al 2020)
Satellite communication covered more range of broadcasting So the security
challenge was considered a big difficulty in satellite communication Downlink
NOMA was assessed with an eavesdropper for the examination of secrecy The
paper concentrated on the physical layer security of downlink satellites Here two
methods were proposed The frequency-domain NOMA was considered for gaining
spectral efficiency The multiple user interferences were obtained in the process of
overlapping Introducing a suitable technique can be performed the security for the
number of users The secrecy rate was analyzed for all authentic users (and the
33
eavesdropper) and expressed in the derivation The safety was improved using the
spectral overlap method (Yin et al 2019)
The NOMA was considered as the emerging scheme in the upcoming wireless
networks The secrecy sum rate for the downlink NOMA (with MIMO multiple
inputs multiple outputs) was examined Downlink NOMA had the base station
number of users and the eavesdropper In the limitation of transmit power and
optimal successive interference cancellation the security was expected to enhance
Downlink MIMO NOMA was considered advantageous because of its secrecy
performance and the practical usage of bandwidth The mutual information rate and
the mean square error were causing the secrecy rate optimization to the problem of
biconvex This was rectified through the alternative optimization method and the
second-order cone programming was solved (Tian et al 2017)
Table 21 Comparative analysis
The comparative analysis for the physical layer security was examined in existing
studies
SR
No
Details of Author wise Contribution to NOMA Technology
1 Author (YFeng Yang amp Yan 2017) Secrecy performance in NOMA was
conducted with the help of artificial noise in the full-duplex mode of relaying
Methodology The optimization of the power was calibrated for the source
information and the noise signal The closed derivation for the secrecy outage
probability was expressed
Usage and limitations The physical security was increased
34
2 Author (He Liu Yang amp Lau 2017) NOMA was developed in the constrain
of security
Methodology The secret message had been sent to some users and also to the
eavesdropper The Novel decoding process was conducted for excluding the
unauthentic users The iterative algorithm was used for power optimization
Usage and limitations Transmit power was reduced The quality of service
was availed
3 Author (D Wang et al 2020) The secrecy was performed in the NOMA
The security was developed against the eavesdropper outside
Methodology The channel state information was analyzed for secrecy The
quantization of CSI had performed for secrecy The derivation for the secrecy
and transmission outage probabilities were obtained
Usage and limitations The secrecy rate was enhanced
4 Author (L Lv et al 2020) The physical security of the NOMA was
improved by adding artificial noise jammer and inter-user interference The
mode of full-duplex in the updated version was used in the NOMA
Methodology The eavesdropper can be trapped the superimposed signal from
the source So the secrecy was affected
Usage and limitations The spectrum usage is effective in the NOMA
transmission scheme Numerous connections can be performed in the NOMA
NOMA is considered to be the most advantageous for the upcoming
generation communications The superimposition technique was followed
4 Author (Yue et al 2020) Secrecy performance of the NOMA was developed
with a unique framework
Methodology The eavesdroppers inside the zone and outside the coverage
zone were examined properly in this paper The outage probability for codendash
power domain NOMA was derived
Usage and limitations Safety was acquired for both internal eavesdropper
and external eavesdropper in this scheme
35
5 Author (Guezouli et al 2020) The heterogeneous sensor network of cellular
communication was taken into account
Methodology Unmanned aerial vehicles are utilized the heterogeneous
sensor network of cellular communication
Usage and limitations Extended the life span of the network system The
cost of the hardware components is drastically low The random and the
repeats in the speedy movement The latency is maximized The coverage
period is maximum
6 Author (Yao amp Xu 2019) The security in transmitting a large amount of
information in the wireless network systems are analyzed with unmanned
aerial vehicle UAV
Methodology The numbers of UAVs are arranged in the space The base
station sent the information to the UAV in the space The authentic receivers
have obtained the secured information from the UAV The HPPP
homogeneous Poisson point process is used for distributing the authentic
receiver and eavesdropper in the line of sight
Usage and limitations The increase in the number of safety zone causing the
secured transmission
7 Author (Saacutenchez et al 2020) Physical security can be achieved by the
method of a unique encryption scheme
Methodology The physical layer security of the following schemes is
discussed in this paper mm-wave NOMA massive multi-input multi-output
heterogeneous sensor networks full-duplex mode
Usage and limitations The physical layer security was analyzed for the 5G
supporting technologies Good reliability achieved The less latent obtained
Machine-type communications can be enabled
36
8 Author (Hou et al 2018) The multi-antennas were used in NOMA with
UAV The stochastic geometric approach was examined
Methodology The multi-input multi-output kind of NOMA was utilized In
common the stochastic geometric approach was used for drastically moving
NOMA
Usage and limitations The maximum signal-to-noise ratio was obtained in
this scheme Power optimization was achieved The path loss is less Good
spectral efficiency was obtained
9 Author (Miao et al 2020) The broadcast type of communication was
performed The less weighed three-dimensional space for 5G communication
was analyzed
Methodology Both the performances of multicast and broadcast were
enabled UAV-assisted 5G communication systems are emerging in the
upcoming wireless networks
Usage and limitations Better flexibility in the network Continuous mobility
One lined line of sight
10 Author (Majhi amp Mitra 2020) The secure communication in cognitive radio
by NOMA was propounded
Methodology The antenna strategy of giving minimum outage probability
was concluded from this study
Usage and limitations The limitation is that more spectral efficiency causes
security issues
11 Author (X Zhao amp Sun 2020) Secure communication of the physical layer
in Visible light NOMA Communication was proposed
Methodology Energy optimization in security constrain was propounded for
achieving overall performance
Usage and limitations It is difficult to find optimal results because energy
optimization is the nonconvex issue
37
12 Author (Tuan amp Hong 2020) Secure communication in simultaneous
wireless information and power transfer NOMA was remitted
Methodology Eavesdropper is used for security purposes between the user
and base station using energy relays Known jammer is used for secure
transmission For energy efficiency storing and transferring were propounded
Usage and limitations Jamming requires extra power allocation
13 Author (Vaezi et al 2019) NOMA for 5G in mmWave MIMO cooperative
and cognitive were analyzed in this study
Methodology SWIFT NOMA is useful for weak receivers
MIMO using more antenna
Usage and limitations multi-antenna utilization cause high power
consumption
14 Author (Vaezi et al 2019) Mobile edge computing NOMA was proposed to
optimize power
Methodology Minimum latency and less power consumption
Usage and limitations Transfer power allocation must be calibrated
15 Author (Faraji-Biregani amp Fotohi 2020) Security in UAV communication
was proposed by introducing mobile agents
Methodology Malicious user of UAV was identified
Usage and limitations Three-phase power is essential
16 Author (G Zhang et al 2019) Secure communication in 5G UAV was
propounded by joint trajectory carrying out in physical layer
Methodology Power optimization was proposed for security
Usage and limitations Security in the physical layer was achieved by
optimization of trajectory
17 Author (Fotohi et al 2020) Agent-based self-protection was propounded in
UAN for secure communication
Methodology This method imitates the immune system of human beings
Less cost
Usage and limitations Energy is not optimized properly This approach
needs to consider other malicious attackers
38
18 Author (Shang Liu Ma amp Fan 2019) Vehicle to everything approach was
propounded for security in a UAV
Methodology Security of vehicle to the vehicle was proposed by considering
eavesdroppers active and passive attacks
Usage and limitations High price
19 Author (Kantor et al 2017) The flight path was calibrated in a UAV
Methodology Security performance was achieved by encryption as well as
anonymization
Usage and limitations High in cost and hardware structure occupies more
place
23 Research Methodology
The NOMA-based cellular architecture for UAV communication has been
considered here as reference network architecture Rayleigh fading has been
assumed as a channel characteristic The performance parameters for PHY layer
security are (1) Pair Outage probability (Pair OP) between two users trusted near
user designated as U1 and untrusted far user designated as U2) and (02) Secrecy
Outage Probability (SOP) of trusted near user designated as U1 The aim is to
achieve optimal Pair OP for the given constrained SOP of User U1 so that network
resources can be efficiently allocated to both users without compromising the
secrecy of trusted User U1
The mathematical analysis from reference literature (ElHalawany et al 2018) has
verified and supported the joint optimization of the Pair OP and SOP for the given
power allocation factor in NOMA This research work is extended as providing
more efficient resource allocation using the POMDP algorithm in a given scenario
First the varying distance of untrusted user U2 from BS as a critical selection
parameter that affects Pair OP amp SOP of user U1 and U2 both has been simulated
and the feasible and infeasible pairing of both users have been analyzed The
optimal power allocation factor for feasible pairing as the constrained problem is
optimized by opting for POMDP as a resource allocation algorithm wherein the
SOP of user U1 is strictly maintained for given CSI POMDP provides optimum
39
power allocation factor for trusted and untrusted users pairing as shown in the
proposed flow of POMDP algorithm is used to model a variety of real-world
sequential decision-making problems After the BS has been set up the distance
between the BS and the user is calculated and if space is less than 200m it is
defined as a trusted user While if the range is more than 200m it is described as
untrusted users In the case of trusted users the channel state information (CSI) is
provided to the proposed algorithm POMDP for reliable and efficient resource
allocation
24 Summary
UAVs play a central role in providing network service recovery in a disaster-
stricken region enhancing public safety networks or handling other emergencies
when Ultra-Reliable Low-Latency Communication is required In particular UAV-
assisted communication can be regarded as an important complement to the 5G
cellular networks Surveyed literature related to UAV communications published
over the past several years emphasized the cybersecurity and channel modeling for
UAV communications etc Security is one of the critical issues in communications
Modern communication networks are based on the layered architecture from the
physical layer up to the application layer A great deal of effort has been made to
develop the cryptographic protocols above the physical layer However the
physical layer is not as robust as that in wired communications The physical layer
in wireless communication is more complex than the counterpart in other
communication paradigms The concerns come from not only the noises but also
many types of fading Recently there has been an influential interest in studying
the security issues in the physical layer Security is highlighted as another
challenge and the implementation of physical layer security techniques is seen as
a difficult task PHY security in NOMA systems under the presence of external
eavesdroppers or untrusted relay nodes Upcoming 5G networks for unpredicted or
crisis (disaster management) the placement of terrestrial substructures is
economically infeasible and challenging due to high operational expenditure as well
as sophisticated and volatile environments
To address such novel issues intelligent heterogeneous architecture by leverage
UAV has been well-thought-out to be a promising novel model For advancing the
40
performance of the UAV 5G communication system physical layer techniques are
of many effects as they have impacted the applications of UAVs Security of
NOMA-based UAV communication network has been scrutinized for optimization
as physical layer security
41
CHAPTER-3
SYSTEM MODEL FOR NOMA-UAV
COMMUNICATION
31 NOMA-UAV System Secured Communication for 5G
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
311 The basic scheme of NOMA
The NOMA system allowed several users to be served simultaneously by the
transmitter To transfer a linear combination of different signals towards the
recipient the system of proportional representation superposition coding (SC) The
transformed signal is provided through
σ ඥ119875119896 119878119896119870119896 =1 -------------------------------------- (1)
Where 119927119948 represents the transmit power assigned toward user k th
119930119948 indicates the normalized message used for user k th
42
The instantaneous total converses power is σ 119927119948119922119948=1 The received signal at user kth
and the eavesdropper are offered through
119910119896 = ℎ119896 σ ඥ119875119896 119878119896119870119896=1 + 119899119896 -------------------------- (2)
119910119890 = ℎ119890 σ ඥ119875119896 119878119896119870119896=1 + 119899119890 -------------------------- (3)
Where 119951119948 and 119951119942 indicated the zero-mean Additive White Gaussian Noise
(AWGN) at user k th with variance 1205901198962 and the zero mean AWGN at eavesdropper
with variance 1206481199422 respectively We assume that the noise variances at all the users
are identical
ie 12059012 = ⋯ = 120590119896
2 = 1205901198902
As per NOMAs process the SIC is followed by all users to decrypt the message to
the same decoding order Notice that it is not known what the optimal decoding
order is for the NOMA method that corresponds to secrecy
Therefore the mth message to be encoded to the user might not be the mth message
to the user As such we also have to add the π variable For example if 120587(1) =
3 then the first message to be decoded for the SIC is the message for the user 120645(119947)
forall j lt k before decoding its letter to remove the inter-user interference successively
Then the user 120645(119948) denotes its message while treating the news for all the user
120645(119946)foralli gt k as the interferences The received Signal-to-interference-plus ndashnoise
ratio (SINRs) at user 120587(119896) k lt K and user 120587(119870) to decode their messages are
respectively given by
119878119868119873119877120587119896=
120574120587(119896)119875120587(119896)
1+120574120587(119896) σ 119875120587(119894)119896119894=119896+1
119896 lt 119870 --------------------(4)
119878119868119873119877120587119870= 120574120587(119870)119875120587(119870) --------------------------------------(5)
Were 120574120587(119896) =หℎ120587(119896)ห
2
1205901199062
൘
43
Also the acknowledged SINR at user 120587(119898) to decrypt the message 120633120645(119948) 119896 lt
119898 le 119870 is given by
119878119868119873119877120587119896=
120574120587(119898)119875120587(119896)
1+120574120587(119898) σ 119875120587(119894)119896119894=119896+1
kltmle 119870 --------------(6)
Similarly the acknowledged SINRs by the eavesdropper of the message 120575119896 119896 lt
119870 and the message 120575119896 are respectively given by
119878119868119873119877120587macr
119896=
120574119890119875120587(119896)
1+120574119890 σ 119875120587(119894)119896119894=119896+1
klt119870 ----------------- ------(7)
119878119868119873119877120587macr
119896=
ȁℎ119890ȁ2119875120587(119896)
1205901198902 = 120574119890119875120587(119896) klt119870 ---------------------(8)
Where 120574119890=ȁℎ119890ȁ2
1205901198902൘
Notice that here expressions for the obtained SINRs at eavesdropper overestimate
the skill of eavesdropper Here a worst-case inference from the viewpoint of
legitimate users is made That is the messages have already been decrypted by the
eavesdropper for all users π (j) forall j lt k before attempting to decrypt the message
for the user π (k)
The presumption also assumes that the decrypting order and power distribution are
understood by the eavesdropper The eavesdropper may or may not recognize the
decoding order of the users and the allocation of power may or may not recognize
the messages for all users π (j) forall j lt k before attempting to decode messages for
users π (k) However since the eavesdropper has been unable to alert the authorized
customers of its capacity and the current CSI the approved user would be unable
to know the eavesdroppers details Therefore we have to pursue the worst-case
scenario for the permissible users point of view due to the liberality required by the
safety reports It highlights that the worst-case assumption in the study and design
of transmission schemes with secrecy requirements has been generally adopted
The proposed study has been evaluated using performance measures Here we
analyze NOMA with downlink and uplink networks suggested by SINR and Sum
44
Rate survey High SNR is then simulated to contrast the OMA and NOMA
processes
312 Downlink of NOMA
The Downlink of the NOMA network on the transmitter side is described in Figure
31 SIC method is supposed to be carried out successively on the receiver side of
each user until another signal is restored The coefficients of users are owed in an
inversely proportional manner based on their available bandwidth
Figure 31 Downlink NOMA network
A consumer with a poor available bandwidth has a transmission capacity of a
higher range than a consumer with strong available bandwidth As a consequence
the consumer with the higher power assumes the signals of other users to be noisy
and automatically restores the signal without conducting any SIC operation The
receiver of each consumer detects indications that are stronger than those of the
desired signal These impulses are then deducted from the power and this process
continues until the signal has been calculated Both users decrypt their signaling by
considering other users with lower correlations The signal is calculated as
45
119904 = σ 119886119894119875119904119883119894119871119894=1 -----------------------------------------------(1)
Where Xi is the user ithrsquos information through unit energy
Ps is the capacity of transmission at the BS
ti is the coefficient of power assigned for user i
Although without the need for lack of generality the channel profits are expected
to be graded as ȁℎ1ȁ2 le ȁℎ2ȁ2 le ⋯ ȁℎ119871ȁ2
Where 119945119923 is the coefficient of the channel of the user Lth
The received signal of the Lth user is calculated as
1199101 = ℎ119897119904 + 119899119897 = ℎ119897 σ ξ119886119894119875119904119883119894119871119894=1 + 119899119897 -----------------------------(2)
Where n1 is zero mean Complex Gaussian noise with a variance of 1206482SINR
analysis with the equation (2) the SNR of Lth user to identify the user 119895 le 1with
119895 ne 1
119878119868119873119877119871 = 1198861120574 ȁℎ1ȁ2120574ȁℎ1ȁ2൘ σ 119886119894 + 1119871
119894=119871+1 ------------------------(3)
Where 120632 = 1198751199041205902ൗ represents the SNR
Sum rate analysis After identifying the SINR of the downlink the sum rate will
also be done quickly
The NOMAs downlink data rate of Lth user can be calculated as
1198771119873119874119872119860minus119889 = 1198971199001198922(1 + 119878119868119873119877119871) --------------------(4)
313 Uplink of NOMA
The Uplink NOMA is depicted in Figure 32 where each user sends a signal to the
BS SIC iterations are supported to classify the signals of mobile users If both
channels are identical and BS sends the coefficients of power allocation to mobile
users the received signal can be interpreted as a synchronous uplink to the NOMA
46
119955 = σ ℎ119894ඥ119886119894119875119909119894119871119894=1 +n ----------------------------------(5)
Where hi is the coefficient of the channel for the ith user
119927119961119946 is the extreme transmission capacity supposed to be general to all users
N is zero-mean Gaussian noise with a variance of 1206482
Figure 32 Uplink NOMA
Analysis of SINR The BS decrypts the signals of the users as per the coefficients
of the users and the SINR for the Lth user can be defined as
119878119868119873119877119871 = 119886119897120574ȁℎ119897ȁ2120574 σ 119886119894ȁℎ119894ȁ2 + 1119897minus1
119894=1൘ ----------------------------(6)
Where 120574 = 1198751205902ൗ indicates SNR
Analysis of Sum rate The sum rate of uplink NOMA when 120632 minus infin can be
computed as
119877119904119906119898119873119874119872119860minus119906 asymp 1198971199001198922(120574 σ ȁℎ119897ȁ119871
119894=1 2 ------------------------ (7)
47
314 Comparison of NOMA and OMA
The attainable data rate of the Lth user of OMA intended for both uplink as well as
the downlink is estimated as
119877119904119906119898119874119872119860 = σ 120572 1198971199001198922120574(1 +
120573119897ȁℎ119897ȁ2
120572119897119871119894=1 ) --------------------------(8)
Just for convenience two users should evaluate the summation of uplink rates for
NOMA and OMA The use of both the uplink rate of NOMA and OMA at high
SNR can be calculated as---
119877119904119906119898119873119874119872119860 asymp 1198971199001198922(120574 ȁℎ1ȁ2 + 120574ȁℎ2ȁ2 ------------------------- (9)
equation (7) and (8) it is seen that 119877119904119906119898119874119872119860 le 119877119904119906119898
119873119874119872119860
Here we note 119929119956119958119950119926119924119912 le 119929119956119958119950
119925119926119924119912 shows that NOMA performed better than OMA in
terms of sum rate in both downlinks as well as uplink of two user networks
The sum rate will be calculated after the SNR as the formulation is shown In this
proposed work multiple users are propagated to the process of NOMA and here a
comparison of NOMA as well OMA has been defined The NOMA uplink and
downlink using the OFDMA method for the
32 PLS performance metrics in NOMA -UAV communication
This chapter mainly describes the proposed work to examine the availability of the
outage probability of the pair below an authorized user According to the decryption
of SIC availability and spectrum sharing the unauthorized user can function as an
eavesdropper and obtain an outage probability (OP) for all situations with the
Secrecy Outage Probability (SOP)
321 SOP and OP - two user and multi-user NOMA system
NOMA system has the capability for assigning multiple data over the transmission
signal through high-level coding (Shim amp An 2018) Thus it contains spectrum
efficiency when opposed to OMA But this has a limitation in security As an
48
instance if the eavesdropper is reached then it obtains multiple user data in the
interference of the NOMA signal Thus the security issues are more significant in
this system Here PLS is an available method to rectify the attack intended for
malicious users (Dai et al 2015)
Additionally data should be transmitted confidentially if the root and eavesdropper
networks can be evaluated and the recipient can decrypt the received text At the
same time the eavesdropper is not able to solve the text that has been interrupted
PLS is at the cutting edge of wireless communication security technology to prevent
eavesdropping attacks The SOP is described as the likelihood that the near users
attainable device confidentiality capability will fall under the predefined target
confidentiality rate as set out in (Shim et al 2017)
Through SOP we can calculate the level of protection of the device As an example
the low-secret OP system makes the system more stable in terms of security than
the high SOP system To boost the efficiency of the PLS CSI-based opportunistic
scheduling links to a scheduled destination in a particular time slot It has been
documented as an enticing scheduling scheme (Long Yang et al 2016) because the
various wireless channel has been exploited Opportunistic scheduling is also
considered to be one of the strategies used to increase the confidentiality efficiency
of the NOMA method
322 System Model
Suppose a multi-user NOMA system of downlink containing BS a selection of K
nearer users as N= 119873119894ȁ12 119870 and a range of M far users as F=
119865119895ȁ12 119872 and an eavesdropper E as displayed in Figure 33 More
specifically nearer users should make active use of the SIC methodology to
distinguish far user F Both the legitimate and illegitimate receivers are furnished
through a single antenna and operate in a half-duplex manner
49
Figure 33 Multi-two user architecture of NOMA system (Shim amp An 2018)
Here 119945119935119936 and ȁ119945119935119936ȁ2
Where X120598ሼ119878ሽ 119884120598119873 cup ሼ119864ሽ represent the channel coefficient and the corresponding
channel gain of the X-Y value
Taking into consideration that each wireless channel for Rayleigh block fading 119945119935119936
can be incorporated as an independently distributed random Gaussian variable with
zero mean and affirmative ℷ119935119936 Variance The outcome of channel gain ȁ119945119935119936ȁ2is an
exponential variable randomly through the Probability Density Function (PDF)
119891ȁℎ119883119884ȁ2(119911) = ቀ1
ℷ119883119884ൗ ቁ 119890119909119901 (minus 119911
ℷ119883119884ൗ )
if zge 0 119900119905ℎ119890119903119908119894119904119890119891ȁℎ119883119884ȁ2(119911) = 0 -----------------(1)
Especially the average channel profit can be represented as
ℷ119883119884= ൬119889119883119884
1198890൘ ൰
minus휀
ℒ ------------------(2)
When 120027 is the attenuation of the received signal 119941119935119936 signifies the distance among
X and Y 1199410 indicates the space and 120656 is the exponent of the path loss It is believed
that the source is entirely familiar with the CSI of both legitimate users and
eavesdroppers
50
323 Partially Observable Markov Decision Process-POMDP
Figure 34 Flow Diagram of the proposed system
The proposed overflow is shown in Figure 34 After the BS has been set up the
distance between the BS and the user is calculated and if space is less than 200m
it is defined as a trusted user While if the range is more than 200m it is described
as untrusted users In the event of untrusted users the channel state information is
accessible to the POMDP accompanied by the allocation of resources The study
was carried out after the machine operation Here a NOMA-oriented cellular setup
provided with a BS at the Centre and two users was described in Figure 35
51
Figure 35 Near and Far User
The adjacent user has a high level of security confirmation needed to protect the
layer since the low-security clearance user is situated at a distance away from the
BS P is specified as the highest level of transmitting power In this chapter it is
presumed that all DNS servers are furnished utilizing an individual antenna and all
channels are supposed to be individually static identical to the Rayleigh
dissemination concerning distribution
119862119873(0 120575119898
minus120572
212059601 2Τ
)
In which 120633119950 is the range between the BS and the nodes 119932119950 Here the path-loss
exponent and constant are defined as 120630 and 1206540 Furthermore BS is assumed to
have predicted the position of the user so that a better CSI can be obtained at BS
that is elaborate in user pairing
The BS transmits the superimposed mixture
119909119905 = ඥ1199051199041 + ඥ1 minus 1199051199042 ------------------------------- (3)
In which 1199561 and 1199562 are the unit of power signals received by users 1199321 and 1199322
respectively t is the power allocation coefficient for the adjacent user
1199031 = ℎ1119909119905ξ119875 + 1198991 ------------------------------- (4)
1199032 = ℎ2119909119905ξ119875 + 1198992 ----------------------------------(5)
Where 1199451119886119899119889 1199452 the channel profit link with the fading of small scale since the
BS to the user 1199321 and 1199322 respectively The additional Gaussian noise with variance
52
is denoted 1199511 119886119899119889 1199512 and zero mean 119894119904 119889119890119899119900119905119890119889119886119904 (1199250) and it is assumed
that the BS conveyed SNR is 120646 = 1199271199250
ൗ
In the NOMA technique additional users with more power may decode their signal
by recognizing the adjacent signal as noise without decoding the adjacent user
message In the previous equation 1198801 is supposed to first solve a weak signal by
decoding its own SIC signal1198802 which is an unauthenticated user attempted to
decrypt the nearer user text after decrypting the adjacent usage text after decoding
its own SIC message The following equation has therefore been achieved
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2 ----------------(6)
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2 ----------------(7)
119879119900119905119886119897119904119894119899119903 = 11987811986811987311987721 1198781198681198731198771
1 119878119868119873119877221198781198681198731198771
2 -----------------(8)
Where 119930119920119925119929119950119951
indicates the SINR ratio of user mth that was decoded by 119932119951 for
119898 119899 isin ሼ119894 2ሽ and the channels gain followed an exponential distribution with the
parameter 120649119950=120654120782120633119950minus120630
324 Problem formulation
As a result the BS could achieve and provide better communication for users who
are vulnerable to security threats from unauthenticated users the proposed
framework identified two kinds of QoS energy efficiency that could be considered
essential for addressing the problem In a particular study a pair of OPs was
specified to check the reliability at which the attainable data rate for users is equal
to or greater than the threshold of minimum reach The following issue aimed at
reducing the pair OP to an SOP factor intended for the user 119932120783 that is provided by
Where 1199270is Outage Probability- (OP)
1199271 is Secrecy Outage probability user U1 119930119926119927(119932120783) and
120631 the permissible SOP threshold
53
33 Performance Analysis Improving PLS Insecurity of NOMA
System
331 The Pair OP Calculation
Through Shannons capacity formula and assuming 119914120783119957119945 119886119899119889 119914120784
119957119945 as the
threshold capacities of users 119932120783 119886119899119889 119932120784 respectively the combination of OP
could be offered by
119927119954 = 120783 minus 119928120783119961119928120784 in which 120649119950 = 120784119940119950119957119945
119950 isin ሼ119946 120784ሽ -------------(9)
empty120783 =120649120784
120646(120783+119957+120649120784119957) empty120784 =120649120783
120646119957
119928120783 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ 120782 lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 ------------------------(10)
Case 1empty1 gt empty2 for having the limitation of the allocation of power factor (t)
required to be satisfied (tgt120649120783
120649120783+120649120784+120649120783120649120784) and for this case 119928120784 could be attained as
follows
119928120784 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ
120649120783
120649120783+120649120784+120649120783120649120784lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 --------------(11)
Case 2 empty1 lt empty2 Like case 1 it was stated that the opposite constraint depends
on
t gt 1206491
1206491+1206492+12064911206492 and 1199282 can be evaluated as follows
119928120784 = ൝119942119961119953 ቀ
minusempty120784
120649120783ቁ 120782 lt
120649120783
120649120783+120649120784+120649120783120649120784
120782 119952119957119945119942119955119960119946119956119942 ---------------------(12)
54
Table 31 List of parameters
Parameters Description
N Number of nearer users
M Number of far users
E Eavesdropper
ℎ119909119910 Channel coefficient between 119909119905ℎchannel and 119910119905ℎ users
119889119883119884 The distance among x and y
1198890 Space
120598 An exponent of the path loss
ℒ Attenuation of the received signal
120575119898 the range between the BS and the nodes
1205960 Path loss constant
120572 Path loss exponent
1199041 1199042 Unit of power signals received by users 1198801 and 1198802
T Power allocation factor for the adjacent user
ℎ1119886119899119889ℎ2 Channel coefficient of 1198801 and 1198802with the fading of small
scale
11989911198861198991198891198992 Gaussian noise variance
1198730 Zero mean for Gaussian noise
120588 Signal to noise ratio
119878119868119873119877119898119899
Signal to interference noise ratio of users n and m channels
55
120591119898 Exponential distribution parameters
1198750 Pair of OP
1198781198741198751 119878119874119875(1198801)
120573 The permissible SOP threshold
Table 31 depicts the list of parameters used in the proposed methodology which
are useful for assigning and the values are assigned based on the parameters given
for the experimental evaluation as well This chapter concludes with the basic and
the actual flow of the proposed method to know more about the work in the
simulation process
332 Pseudo-code for the proposed algorithm
Algorithm I
Step 1 Estimate Rayleigh distribution
119862119873(0 120575119898minus120572 2Τ
1205961199001 2Τ
) where
120633119950 is the distance between nodes 119932119950 and the BS
120630 is the path-loss exponent and
120654119952 is the path-loss constant
Step 2 The BS broadcasts the superimposed mixture and input signal as follows
119909119905 = ξ1199051199041 + ξ1 minus 1199051199042
Where 119956120783 and 119956120784 are the unit power signals received by users 119932120783 and 119932120784
respectively 119957 is the Power allocation coefficient for the near user
Step 3 The received signal is as follows
1199031 = ℎ1119909119905ξ119875 + 1198991
1199032 = ℎ2119909119905ξ119875 + 1198992 where
56
119945120783 and 119945120784 are the channel gain associated with the
small-scale fading from the BS to users 119932120783 and 119932120784 respectively
1199511 and 1199512 are the additive white Gaussian noise with zero mean and variance
119925120782
Step 4 the BS transmit signal-to-noise ratio (SNR)
120646 = 119927119925120782
Step 5 Signal-to-Interference-plus-Noise-Ratio (SINR) for the two users 119932120783
decodes the signal of the weak user first then decodes its own signal after using
SIC 119932120784 is an untrusted user and tries to decode the near user message after
decoding its own message using SIC
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588ൗ and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ2ȁ2+1120588ൗ and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2
119879119900119905119886119897119904119894119899119903 = ሼ11987811986811987311987721 1198781198681198731198771
1 11987811986811987311987722 1198781198681198731198771
2ሽ
where 119930119920119925119929119950119951
is the signal-to-interference-plus-noise-ratio (SINR)
of user 119950th decoded by 119932119951 for 119898 119899120598ሼ119894 2ሽ and ȁ119945119950ȁ2 is the
channels gain of 119932119950
Algorithm II
Partially observable Markov decision process
Step 1 Prediction of the maximum capacity of channel with respect to the data rate
119955119943 = 119877(119878119909119863)
S is denoted as states
Let D be the channel characteristics which are considering here as actions
Reward function R
Step 2 The agent receives an observation 119900120598120118which depends on the new state of
the environment 119930prime and on the just taken action 119941 with probability
119926(119952ȁ119956prime 119941)
Step 3 Reward earned at time t is expressed as
57
119903119891119905 = 119877(119878119909119863)119905
Step 4 reward function on belief states
119919 is the belief states over POMDP states
119919119943 is the belief state transition function
119955119943 = 119877(119867119909119863)
Step 5 The reward function is updated based on the belief MDP the agent only
cares about which action will yield the largest expected immediate reward ie the
maximum capacity channel
119861119891 ቀℎ 119889 ℎprimeቁ = 119875119903 (
119900120598120118
ℎprimeȁℎ 119889 119900) 119875119903(119900ȁ119889 ℎ) 119861119891
119875119903(ℎprimeȁℎ 119889 119900) = ቄ1119894119891119905ℎ119890119887119890119897119894119890119891119906119901119889119886119905119890119908119894119905ℎ119886119903119892119906119898119890119899119905119904ℎ 119889 119900119903119890119905119906119903119899119904ℎprime
0119900119905ℎ119890119903119908119894119904119890
119903119891(ℎ 119889) = σ ℎ(119904)119877(119904 119889)119904isin119878
34 SUMMARY
The NOMA-UAV communication framework has been proposed in this research
work and the Physical Layer security aspect has been focused on for optimization
The PLS performance metrics selected are SOP amp Pair OP in the proposed system
model The POMDP framework is general enough to model a variety of real-world
sequential decision-making problems Applications include robot navigation
problems machine maintenance and planning under uncertainty in general Here
we have adopted the User pairing POMDP algorithm for resource allocation in two
users amp multi-user NOMA-UAV communication networks The proposed study has
been evaluated using performance measures by varying distances of trusted amp
untrusted users from the base station as well as for varying SINR conditions The
simulation results and outcomes are discussed in a further chapter
58
CHAPTER 4
RESULT AND DISCUSSION
41 PERFORMANCE MEASURES OF SECURED NOMA-
UAV COMMUNICATION MODEL
Drones or UAV-based communication technology has been thoroughly studied and
adopted by the 3GPP standard UAV systems have been envisaged to form an
integral part of future wireless communication applications due to their dynamic
flexible and flying nature Due to their ability to reach higher altitudes they usually
have dominant LOS channels with the ground nodes This capability can be used to
provide confidentiality to the legitimate receivers against the eavesdroppers This
can be done by deploying UAVs to launch more effective jamming signal attacks
to terrestrial eavesdroppers The conventional cooperative jamming schemes make
an assumption that the locations of terrestrial jammers are fixed which might
compromise the secrecy of the system if the jammers are located far away from the
eavesdroppers and is also not practical as it makes an assumption of perfect CSI of
the jammer to eavesdropper channel
Here in the proposed scenario of the NOMA-UAV communication network two
key PHY layer security metrics SOP amp Pair Outage Probability have been jointly
optimized for a more effective power allocation factor for NOMA cellular
architecture The varying channel characteristics have been analyzed to achieve the
desired SOP with the constrained threshold minimum target secrecy rate for the
two-user scenario POMDP Algorithm iteratively provides the optimized SINR that
has been used to keep trusted users in pair with the untrusted user with minimum
achievable outage probability
The proposed NOMA-UAV System model has been simulated in MATLAB 2019b
version with mainly Communications System Toolbox Optimization Toolbox RF
Toolbox Signal Processing Toolbox Statistics and Machine Learning Toolbox
The simulation has been carried out for two-user pair to achieve desired secrecy
target rate and feasible pairing between trusted user amp untrusted user(eves-dropper)
59
The optimal-outage performance of minimized pair OP subjected to SOP constraint
has been solved by both dynamic programming optimization and POMDP
optimization approaches
The simulation of the proposed framework for the UAV-NOMA communication
network has been carried out and discussed in two parts two user models and a
multi-user model as below mentioned discussion The base station is deployed at
the center of a cell of radius 1000 m There are two users in the system under
consideration The channel between two nodes in the system suffers both the small-
scale fading and path loss effect Small-scale fading follows the exponential
distribution with the mean value 1 The noise signal of all channels has a Gaussian
distribution with 0 mean and variance 1 The path loss exponent α and the path loss
constant PLo are set to 2 and 01 respectively We assume a normalized bandwidth
of 1 Hz The SOP constraint threshold is assumed 01 and the target secrecy rate is
001 The power allocation coefficient is 015 and the BS transmitted SINR is
assumed 15dB for the proposed model As per the NOMA transmission scheme
SINR has been obtained for User 1 amp User 2 both for SIC decoding POMDP
algorithm optimally tunes the SINR value for User 1 amp User 2 that is considered to
select optimal power allocation coefficient for both trusted and untrusted users with
respective SOP of User1
42 Numerical results and Discussion
Table 41 Simulation Parameters
Parameters Values
Untrusted user Distance (d2) 200-1000 (300 700)
BS transmit signal-to-noise ratio (SNR) (120588) in dB 15
Sop constraint constant threshold (β) 01
Power allocation factor (t) 015
Trusted User distance (d1) 2-
60
Cell Radius (rd) 1000 meters
Path loss exponent (α) 2
Path loss constant (PLo) 01
Normalized bandwidth in Hz 1
Target secrecy rate (Rs) 001
No of Bits 100
Pair Outage Probability (P0) 05250
SINR 5319 15305 5162
10247
421 Feasible amp Infeasible pairing of trusted amp Untrusted users
In this section the CSI value broadcasted by Base Station is assumed 15 dB initially
and for varying channel conditions various SINR values of 120646 = minus20 minus10 20 dB
is described with target secrecy rate 0005 and 001 for power allocation coefficient
015 and User 1 distance at 200m is shown in the Figure 41 below
Figure 41 Impact on Sop with increase distance between BS and user U2
61
Varying target secrecy rate threshold from 0005 to 001 the obtained result in
Figure 42 revealed that the 1199321 is a gradually reducing function for the distance of
untrusted user d2 that implies that the increasing value of d2 leads to the
improvement of the SOP of 1198801
Figure42 Impact on Sop with increase distance between BS and user U2
Since the offered constant threshold 120656 in SOP limit1199322 which should be located at
a larger space when compared with a value of threshold to attain the SOP of 1199321
apart from that it is expected the high target secrecy rate maximizes the SOP of 1199321
Here in below figure the power allocation coefficient has been varied from 0 to 1
with threshold value of t and the desired t_sop for feasible pairing
Figure 43 Feasible pairing t Vs pair OP
62
Pair OP in case of rising 1199322 untrusted user in d2 for different BS transfer the SNR
where t= 015 and d1=200mThe infeasible pairing of SOP (1199321) and the OP pair
by the enhanced allocation of the power (t) d1 (200m) d2 (300m) 120646 = 15 dB and
120656 = 0
Figure 44 shows the identical plotting of data by adjusting the unauthenticated
level of the user through converting it to a BS closer distance (d2=300m) Accuracy
is compared and checked with the full spectrum of numerical simulations The
result has shown that the effectiveness is based on a comparative study of the two
consumers of the BS
Figure 44 Infeasible pairing t Vs pair OP
422 The Secrecy Outage Probability amp Pair Outage Probability
Feasible paring in the SOP of pair OP and 1199321 with the improved power allocation
factor t in which d2=700m d1=200m 120646 = 15119889119861 and The result described that
the OP and SOP of the user 1199321 with increased for two various distances of the 1199322
untrusted user The simulation result approves the convex nature 120656 = 0 1of the OP
and the SOP is sequentially decreased depending on t Generally when it enhances
the power owed to the weak user text reduces that develop the ability of 1198802 for
discerning the superior positioned signals therefore enhancing the SOP of 1198801
63
Figure 45 Secrecy outage probability
Figure 46 Pair outage probability
423 SNR versus Strictly Positive Secrecy Rate
Figure 47 proved that the potential for confidentiality is superior to the existing
techniques The proposed application for pre-coding improves the efficiency of the
device The transmission power of the system is the power needed for the
transmission of particular data
64
Figure 47 SNR versus Strictly positive secrecy rate
If there is a growth in the number of users there is a risk of inference in the
transmission of data and thus the reliability of the data rate may be affected Based
on these cases the efficiency of the antenna power to be withheld and occupy the
data determined
424 Power radiated by per MMBs antenna
In the case of multi-users scenario when there are more than two users then the
allocation of an optimized resource block to all users is the key parameter to achieve
desired outage efficiency because strong users require higher SNR for higher data
rates and weak users are allocated minimum threshold SNR for lower data rate
requirements to maintain suitable pairing OP and SOP balance
Figure 48 Power radiated by per MMBs antenna
65
So the POMDP policy optimization has shown better performance over the
dynamic programming approach particularly when more users are active (a greater
number of antennas as in Figure 48 the overall radiated power per BS antenna in
downlink has been considerably reduced
43 CONCLUSION AND SCOPE OF FUTURE WORK
431 Conclusion
Starting with LTE (4G) OFDMA has replaced WCDMA with mobile cellular
communications and will also be used during advanced 5G while Non-Orthogonal
Multiple Access (NOMA) has recently been recognized as a groundbreaking PHY
technology in UAV communication NOMA scheme is used in place to increase the
effective use of small resources such as in UAV communication where the data rate
is very low and critical decision making is of utmost importance
The critical need for UAV communication is a secure PHY layer for mission-
critical applications and as NOMA doesnrsquot promise high security the proposed
research work has been carried out to enhance the insecurities of NOMA-UAV
communication In this proposed research work the probabilities of confidential
outage (SOP) and OP were investigated in the two-user NOMA system Here BS is
required to pair a trusted or permissible user with other untrusted users due to the
unequal distribution of untrusted and trusted users in the cell The SIC is then
applied to the receiver side intended for decoding the message signals The Pair OP
of both users has been analyzed for varying Target Secrecy Rate (Rs) of the trusted
user U1 which provides constraint threshold of the SOP of U1
By varying the distance of Untrusted users from BS the optimal distance and power
allocation factor for the feasible pairing of trusted and untrusted users without
compromising the secrecy outage probability of U1 has been achieved in simulation
results
POMDP has provided the optimal power allocation as a resource allocation
algorithm in the dynamically changing environment of two user NOMA cases
where the distance between BS and untrusted user varies significantly The
performance of secure NOMA-UAV is affected critically by (SOP of User 1) which
66
should be optimally selected to maintain the proposed Pair OP between both users
and the simulation results have supported this optimal outage performance Thus
NOMA-UAV architecture has the potential of providing a secure PHY layer for
mission-critical applications by opting for suitable decision-making resource
algorithm POMDP
431 Scope of Future Work
Furthermore the multiuser scenario with the increased number of Untrusted users
can be analytically verified and simulated in the same direction for NOMA-UAV
communication to improve transmission security and reliability In addition more
adaptive and efficient Resource allocation algorithms for NOMA-UAV networks
with secured performance in real-time applications should be investigated
1
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Liu Y Pan G Zhang H amp Song M (2016) On the capacity comparison
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Liu Y Qin Z Elkashlan M Gao Y amp Hanzo L (2017) Enhancing the
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11
PUBLICATIONS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495449|P a g e
Migration from 4g LTE to Advanced PHY Techniques for
Unmanned Aerial Vehicle (UAV) Communication
Pankaj Patel PHD StudentGujarat Technological UniversityGujarat India
ABSTRACT
UAV (unmanned aerial vehicles) with their high mobility and low cost have found a wide range of applications
during the past few decades Historically UAVs have been primarily used in the military mainly deployed in
hostile territory to reduce pilot losses With continuous cost reduction and device miniaturization small UAVs
are now more easily accessible to the public hence numerous new applications in the civilian and commercial
domains have emerged For the sake of boosting resilience against faults natural disasters and unexpected
traffic the Unmanned Aerial Vehicle (UAV) assisted wireless communication systems can provide a unique
opportunity to cater for such demands in a timely fashion without relying on the overly-engineered cellular
network However for UAV-assisted communication issues of capacity coverage and energy efficiency are
considered of paramount importance Starting with LTE (4G) Orthogonal Frequency Division Multiple Access
(OFDMA) has replaced WCDMA for cellular mobile communications and it will also be employed in advanced
5G yet Non-orthogonal multiple access (NOMA) has been recently recognized as a promising PHY technique
to significantly improve the spectral efficiency of mobile communication networks In this paper we provide an
overview of UAV-aided wireless communications by introducing the basic networking architecture
highlighting the key design considerations as well as the new opportunities to be exploited
Keywords LTE (4G) Non-orthogonal multiple access (NOMA) Unmanned Aerial Vehicle (UAV) Wireless
communication
----------------------------------------------------------------------------------------------------------------------------- ---------
Date Of Submission 26-04-2019 Date Of Acceptance 06-05-2019
----------------------------------------------------------------------------------------------------------------------------- ----------
I INTRODUCTION The use of unmanned aerial vehicles
(UAVs) will grow rapidly in the next decade These
remotely piloted or preprogrammed aircraft are
envisioned for applications in numerous civil
settings including industrial monitoring scientific
data gathering agriculture public safety and search
and rescue Many other applications - presently
unforeseen - will inevitably also arise These
vehicles also known as the unfortunate misnomer of
drones must be integrated into the national
airspace system and into the airspace worldwide A
natural concern in the use of UAV is safety and this
has direct implications for the control and non-
payload communication systems that must be used
to operate it efficiently Similarly navigation and
surveillance functions must be made more reliable
and more accurate Because of these factors many
UAV research development testing and
standardization efforts are underway by
governments industries and academia Despite the
fact that piloted civil aircraft have been flying safely
for decades UAV presents distinct new challenges
in the form of different flight profiles eg low-
elevation flights and more high-dynamic maneuvers
wider required bandwidths eg for video and
different ground site characteristics such as locations
in cluttered areas and lower elevation antennas
In this paper first the evolution of radio
technologies considered in UAV wireless
communication is reviewed in literature survey and
the significant work in the area is highlighted along
with the newest challenges The reminder of this
paper is organized as follows
The promising technology NOMA and its
variants are discussed in section three In Section
four the system model and assumptions are
presented and in section five the comparative
analysis of NOMA with existing popular technology
OFDMA (OMA) is given with simulation
persormance analysis At last the work is concluded
in section five
II LITERATURE SURVEY Drones variously known as unmanned
aerial vehicles (UAVs) unmanned aerial systems
(UAS) or remotely piloted aircraft system (RPAS)
are used in several parts of the world for surveying
and aerial mapping disaster management work
monitoring crop production and infrastructure
activities besides commercial photography and
courier delivery The viability of UAV as a
multipurpose research vehiclehas driven great
RESEARCH ARTICLE OPEN ACCESS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495450|P a g e
interest since recent decades[1] The
basictechnology building blocks responsible for the
current advancesinclude airframes propulsion
systems payloadssafety or protection systems
launch and recovery dataprocessor ground control
station navigation and guidanceand autonomous
flight controllers The following briefsurvey is
focused on the area of navigation guidance
andcontrol of UAVs Various control design for
UAVs has beenproposed ranging from linear to
nonlinear synthesis timeinvariant to parameter
varying and conventional PID tointelligent control
approaches The developed controllershave been
implemented for different aerial platforms
airship(blimp) fixed-wing UAV small scale
helicopteruad-rotors and MAV Wireless
communication systems that include unmanned
aerial vehicles promise to provide cost-effective
wireless connectivity for devices without
infrastructure coverage Compared to terrestrial
communications or those based on high-altitude
platforms on-demand wireless systems with low-
altitude UAVs are in general faster to deploy more
flexibly reconfigured and likely to have better
communication channels due to the presence of
short-range line-of-sight links However the
utilization of highly mobile and energy-constrained
UAVs for wireless communications also introduces
many new challenges In India for the regulation
and safety purpose in commercial and survilence
applications the policy guideliens also introduced
as below
Table 1UAV communication Policy Guidelines for
commercial and surveillance purpose
III MIGRATION FROM 4G LTE TO 5G The fruitful deployment of UAV based
communicationsystems for 4G and beyond future
wireless networks is highlyinvolved in finding joint
solutions to challenge of ubiquitousconnectivity with
both a multitude of devices in a spectralefficient way
as well as with energy-efficient transmissionand
operation of the UAV-BS for maximized and
armonizedcoverage and capacity [2][3] It should be
noted that suitableenergy efficiency for the UAV-
assisted ommunication systemachieves paramount
importance in the overall performance ofthe system
Efficient energy consumption results in
enhancedairtime for the communication system
improving bitsJoulesfor a given energy level
Furthermore coverage and capacityof an aerial cell
are attributed to many factors such as
thetransmission power antenna gains UAV
altitude deploymentenvironment and prominently
radio access technology [4]
4G is the fourth generation of broadband
cellular network technology succeeding 3G and
besides the popular techniques in 3G4G ie
TDMAWCDMAOFDMA a new radio access
technology NOMA is also developed by researchers
to be used in communication networks due to its
capability in increasing the system capacity
Recently non-orthogonality based system designs
are developed to be used in communication
networks and have gained significant attention of
researchers Hence multiple access (MA) techniques
can now be fundamentally categorized as orthogonal
multiple access (OMA) and non-orthogonal
multiple access (NOMA) In OMA each user can
exploit orthogonalcommunication resources either
within a specific time slot frequency band or code in
order to avoid multiple access interference The
previous generations of networks have employed
OMA schemes such as frequency division multiple
access (FDMA) of first generation (1G)time
division multiple access (TDMA) of 2G code
division multiple access (CDMA) of 3G and
orthogonal frequency division multiple access
(OFDMA) of 4G
In NOMA multiple userscan utilize non-
orthogonal resources concurrently by yielding a high
spectral efficiency while allowing some degree of
multiple access interference at receivers Recently
NOMA reputations have climbedsharply as a
fundamental solution to the challenges
encompassingthe next generation wireless networks
[5][6]NOMA has been proved to exhibit improved
spectral efficiencybalanced and air access as
compared to OMAtechnologies[6] with the ability
to cater for multipledevices in the same frequency
time or code resource thusproviding efficient access
to massive connected devices Furthermore NOMA
is also instrumental in reducingthe interference by
employing orthogonal resources as inOrthogonal
Frequency Division Multiple Access
(OFDMA)[7][17] or by sharing a single beam
between multiple users forintra-cluster access and
using NOMA for inter-cluster access[18]Current
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495451|P a g e
studies have focused on provisioning Air to
Ground(A2G) communication services mainly
through placement op- timization under various
viewpoints in literature The performance of UAV
based communication systems hasalso been
addressed for the underlaid Device to Device(D2D)
deployment scenario This work assumed
interferenceraised by D2D network nodes without
considering the presenceof terrestrial BS
Additionally there have been a fewstudies
discussing the performance of NOMA for UAV
basedcommunication system[8] A NOMA enabled
fixedwingUAV deployment was proposed in [8] to
support coveragefor ground users situated outside
BS offloaded location
In general NOMA schemes can be
classified into two types power-domain
multiplexing andcode-domain multiplexing In
power-domain multiplexing different users are
allocated[7][8][9][6][5][1][10] differentpower
coefficients according to their channel conditions in
order to achieve a high systemperformance In
particular multiple usersrsquo information signals are
superimposed at the transmitterside At the receiver
side successive interference cancellation (SIC) is
applied for decoding thesignals one by one until the
desired userrsquos signal is obtained providing a good
trade-offbetween the throughput of the system and
the user fairness In code-domain multiplexing
different users are allocated different codes and
multiplexed over the same time-frequencyresources
such as multi-user shared access (MUSA) sparse
code multiple access (SCMA) and low-density
spreading (LDS) In addition to power-domain
multiplexing and codedomain multiplexing there are
other NOMA schemes such as pattern division
multiple access(PDMA) and bit division
multiplexing (BDM) Although code-domain
multiplexinghas a potential to enhance spectral
efficiency it requires a high transmission bandwidth
andis not easily applicable to the current systems
On the other hand power-domain multiplexinghas a
simple implementation as considerable changes are
not required on the existing networksAlso it does
not require additional bandwidth in order to improve
spectral efficiency Inthis paper the prime focusis on
the power-domain NOMAAlthough OMA
techniques can achieve a good system performance
even with simple receiversbecause of no mutual
interference among users in an ideal setting they
still do not have theability to address the emerging
challenges due to the increasing demands in future
networks andbeyond
The superiority of NOMA over OMA can
besummarized as follows
_ Spectral efficiency and throughput In OMA such
as in OFDMA a specific frequencyresource is
assigned to each user even it experiences a good or
bad channel conditionthus the overall system suffers
from low spectral efficiency and throughput In
contrary inNOMA the same frequency resource is
assigned to multiple mobile users with good and
bad channel conditions at the same time Hence the
resource assigned for the weak user isalso used by
the strong user and the interference can be mitigated
through SIC processesat usersrsquo receivers Therefore
the probability of having improved spectral
efficiency and ahigh throughput will be considerably
increased
_ User fairness low latency and massive
connectivity In OMA for example in OFDMAwith
scheduling the user with a good channel condition
has a higher priority to be servedwhile the user with
a bad channel condition has to wait to access which
leads to a fairnessproblem and high latency This
approach cannot support massive connectivity
HoweverNOMA can serve multiple users with
different channel conditions simultaneously
thereforeit can provide improved user fairness lower
latency and higher massive connectivity
_ Compatibility NOMA is also compatible
with the current and future communication
systemssince it does not require significant
modifications on the existing architecture For
exampleNOMA has been included in third
generation partnership project long-term
evolutionadvanced (3GPP LTE Release 13)
Figure 1Pictorial comparison of NOMA Vs OMA
Although NOMA has many features that
may support next generationsit has some limitations
that should be addressed in order to exploit its full
advantage set Thoselimitations can be pointed out
as follows In NOMA since each user requires to
decode thesignals of some users before decoding its
own signal the receiver computational
complexitywill be increased when compared to
OMA leading to a longer delay Moreover
informationof channel gains of all users should be
fed back to the base station (BS) but this results in
asignificant channel state information (CSI)
feedback overhead Furthermore if any errors
occurduring SIC processes at any user then the error
probability of successive decoding will beincreased
As a result the number of users should be reduced to
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495452|P a g e
avoid such error propagationAnother reason for
restricting the number of users is that considerable
channel gain differencesamong users with different
channel conditions are needed to have a better
network performance
IV NOMA UPLINK AND DOWNLINK
SCENERIO SIMULATION ANALYSIS In this section an overview of NOMA in
downlink and uplink networks is introduced
throughsignal-to-interference-and-noise ratio (SINR)
and sum rate analyses Then high signal-to-
noiseratio (SNR) analysis has been conducted in
order to compare the performances of OMA
andNOMA techniques[10]
A Downlink NOMA Network
At the transmitter side of downlink NOMA
network as shown in Fig 2 the BS transmits
thecombined signal which is a superposition of the
desired signals of multiple users with different
allocated power coefficients to all mobile users At
the receiver of each user SIC process isassumed to
be performed successively until userrsquos signal is
recovered Power coefficients ofusers are allocated
according to their channel conditions in an inversely
proportional mannerThe user with a bad channel
condition is allocated higher transmission power
than the one which has a good channel condition
Thus since the user with the highest transmission
power considers the signals of other users as noise
and recovers its signal immediately without
performing anySIC process However other users
need to perform SIC processes In SIC each userrsquos
receiverfirst detects the signals that are stronger than
its own desired signal Next those signals
aresubtracted from the received signal and this
process continues until the related userrsquos own signal
is determined Finally each user decodes its own
signal by treating other users with lower
powercoefficients as noise The transmitted signal at
the BS can be written as
s = aiPsxi
L
i=1
where xi is the information of user i (Ui)
with unit energy Ps is the transmission power atthe
BS and ai is the power coefficient allocated for user
i subjected to ai = 1Li=1 and a1gea2gehellip geaL since
without loss of generality the channel gains are
assumed to be ordered as h1 2 le h2 2 le⋯ hL 2 where hL is the channel coefficient of Lth
user based on NOMAconcept The received signal
at lth user can be expressed as follows
y1 = hls + nl = hl aiPsxi + nlL
i=1
where nlis zero mean complex additive Gaussian
noise with a variance of σ2
(1) SINR analysis By using (2) the instantaneous
SINR of the lth user to detect the jth user jle l
with jne L can be written as
SINRl = alγ hl 2
γ hl 2 aiLi=l+1 + 1
Where γ = Psσ2 denotes the SNR
(2) Sum rate analysis After finding the SINR
expressions of downlink NOMA the sumrate
analysis can easily be done The downlink
NOMA achievable data rate of lth user can
beexpressed as
RlNOMA-d
= log2 1 + SINRl = log2(1 +alγhl2γhl2 i=l+1Lai+1
B Uplink NOMA Network
In uplink NOMA network as depicted in
Fig 3 each mobile user transmits its signal to the
BS At the BS SIC iterations are carried out in order
to detect the signals of mobile users By assuming
that downlink and uplink channels are reciprocal and
the BS transmits power allocation coefficients to
mobile users the received signal at the BS for
synchronous uplink NOMA can be expressed as
r = hi aiPxi + n
L
i=1
where hi is the channel coefficient of the ith
user Pxi is the maximum transmission power
assumed to be common for all users and n is zero
mean complex additive Gaussian noise with a
variance of σ2
Figure 2Downlink NOMA network
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495453|P a g e
Figure 3 Uplink NOMA network
1) SINR analysis The BS decodes the signals of
users orderly according to power coefficientsof
users and then the SINR for lth user l ne 1 can
be given by
SINRl =alγ hl 2
γ ai hi 2 + 1lminus1i=1
where γ =P
σ2
2) Sum rate analysis The sum rate of uplink
NOMA when γ minus infincan be written as
Rsum NOMA-u asymp log2(γ hl 2L
l=1
C Comparing NOMA and OMA
The achievable data rate of the lth user of OMA for
both uplink and downlink can be expressed
RsumOMA = αl log2(1 +
βlγ hl 2
αl)L
l=1
For the sake of simplicity sum rates of
uplink NOMA and OMA can be compared for
twousers Then using both the sum rate of uplink
NOMA and OMA at high SNR can beexpressed
respectively as
RsumNOMAasymp log2 γ h1 2 + γ h2 2
Here we notice ROMA
sumle RNOMA
sum
Fig shows that NOMA outperforms OMA in terms
of sum rate in both downlink and uplinkof two
user networks
V SIMULATION RESULTS
The Comparative analysis of modelling
Downlink and Uplink NOMA in comparison with
OMA is simulated and findings are presented that
shows superiority of NOMA over OMA with better
spectral efficiency for simulation parameters taken
as power allocation coefficients a1=06 a2=04 and
channel responses h1 2
=0 DB h22=20 DB
parameters
Figure 4NOMA UPLINK
Figure 5 NOMA DOWNLINK
VI CONCLUSION This paper investigated an account of
NOMArsquos applicability for UAV-assisted
communication systems NOMA schemes are
proposed to improve the efficient usage of limited
network sources OMA based approaches that use
time frequency or code domain in an orthogonal
manner cannot effectively utilize radio resources
limiting the number of users that can be served
simultaneously In order to overcome such
drawbacks and to increase the multiple access
efficiency NOMA technique has been recently
proposed Accordingly users are separated in the
power domain Such a power domain based multiple
access scheme provides effective throughput
improvements depending on the channel conditions
The crucial need of UAV communication of
optimum utilization of available licensed spectrum
bandwidth is considered here and simulation results
taken presented that NOMA performs better than
OMA while fulfilling individual user-rate constraint
for both users The research work can be further
carried out investigating joint power and phase
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495454|P a g e
allocation of UAV nodes deployment for efficient
operations
REFERENCES [1] S M I C Y L M I Muhammad Farhan Sohail
Non-Orthogonal Multiple Access for Unmanned
Aerial Vehicle Assisted Communication in IEEE
access 2018
[2] M Mozaffari Drone small cells in the clouds
Design deployment and performance analysis in
IEEE Global Communications Conference 2015
[3] R Z a T J L Y Zeng Wireless
communications with unmanned aerial vehicles
opportunities and challenges in IEEE
communication magazine 2016
[4] I B-Y a H Yanikomeroglu The new frontier in
ran heterogeneity Multi-tier drone-cells IEEE
Communications Magazine pp 48-55 2016
[5] P K S a D I Kim Uav-enabled downlink
wireless system with NOMA access in IEEE
Globecom Workshops Dec 2017
[6] P Xu and K Cumanan Optimal power allocation
scheme for nonorthogonal multiple access with
fairness in IEEE Journal on Selected Areas in
Communications oct 2017
[7] E H a D I K S Ali Non-orthogonal multiple
access (noma) for downlink multiuser mimo
systems User clustering beamforming and power
allocation in IEEE Access 2017
[8] W S M B a M D M Mozaffari Unmanned
aerial vehicle with underlaid device-to-device
communications Performance tradeoffs in IEEE
Transactions on Wireless Communications June
2016
[9] Z D X D a R Z Z Chen An optimization
perspective of the superiority of noma compared to
conventional oma in IEEE Transactions on
Signal Processing Oct 2017
[10] M T Mahmoud Aldababsa1 and S G G K 2 A
Tutorial on Non-Orthogonal Multiple Access
2017
[11] X L Z J W a K J R L Zhu Han Delay
Sensitive Scheduling Schemes for Heterogeneous
QoS over Wireless Networks IEEE
TRANSACTIONS ON WIRELESS
COMMUNICATIONS VOL 6 NO 2
FEBRUARY 2007 vol 6 no 2 2007
[12] Z J W a K J R L Z Han A resource
allocation framework with credit system and user
autonomy over heterogeneous wireless networks
in IEEE Global Telecommunications Conference
2003
[13] N B S a P S S Chen Heterogeneous delay
tolerant task scheduling and energy management in
the smart grid with renewable energy IEEE
Journal of Selected Areas in Communications vol
31 no 07 pp 1258-1267 july 2013
[14] H L Z C a Z H Y Hu Scheduling strategy for
multimedia IEEE Transactions on Vehicular
Technology July 2016
[15] P F a K B L Y Dong High-speed railway
wireless communications efficiency vs fairness
IEEE Transactions on Vehicular Technology vol
63 no 2 pp 925-930 march 2014
[16] T R a Z H Z Chang Queueing game for
spectrum access in cognitive radio networks
IEEE Communications Letters vol 19 no 11 pp
2017-2020 June 2015
[17] Z C L T R a Z H F I Yun Hu Service
Provisioning and User Association for
Heterogeneous Wireless Railway Networks IEEE
Transactions on Communications 2017
[18] H S W Tianti Chen Optimal Scheduling for
Wireless On-Demand Data Packet Delivery to
High-Speed Trains IEEE Transactions on
Vehicular Technology vol 64 no 9 pp 4101 -
4112 september 2015
Pankaj Patel Migration from 4g LTE to Advanced PHY Techniques for Unmanned Aerial
Vehicle Communication International Journal of Engineering Research and Applications
(IJERA) Vol 09 No04 2019 pp 49-54
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Improving Of Physical Layer Insecurity Of The
Non Orthogonal Multiple Access System
Pankaj M Patel Prof Dr Chetan B Bhatt
Abstract The key aspect of the NOMA (power domain non orthogonal) is the user possibility for decoding the messages belonging to another pair users
on similar resources The method interprets a security threat especially in the case where the base station serves the users with various security
clearance or untrusted users The main aspect of NOMA is to serve the multiple users upon the similar radio resources at the minimal inter user
interference expense The system not only permits the serving of particular users with high efficient bandwidth but also permits the scheduling more type
of users than the timely available users In this study we investigated the secrecy outage probability (SOP) and OP in the both two user and multi user
NOMA system where the BS is supposed to pair a trusted or legitimate user with other untrusted users because of the un even distribution of the
untrusted and trusted users in the cell SIC the successive interference cancellation was then implemented at the receiver side for decoding the
message signals With the application of NOMA concept the study investigated the pair outage behavior under the SOP constraints on the trusted users
In specific the SOP and OP of the concerned U1 were obtained in the closed type of expressions The study also provided the understanding the
possibility of obtaining an optimal outage efficiency for pairing under the SOP constraints With certain numerical simulations the study verified the
effectiveness of the analytical derivations with respect to various scenarios
Index Terms NOMA Secrecy outage Probability Successive Interference Cancellation bandwidth channel state information etc
mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash
1 INTRODUCTION The physical layer security and non-orthogonal multiple
access was regarded as the encouraging techniques for the
processing of wireless communication network systems Today
the combination of the two significant communication methods
was studied to guarantee a spectral efficient and secure
wireless transmission Most of the prevailing works
predominantly concentrated on the optimization and efficiency
of the PLS in the existence of untrusted relay nodes and
external eavesdroppers(Arafa et al 2019a)But there occurs a
gap in the theoretical studies to describe the ease of obtaining
the enhanced efficiency in the existence of untrusted users
Recently the network traffic amount have greatly enhanced
particularly with the updated growth in IoT applications in
future To rectify the huge traffic demand upcoming wireless
networks must deliver a best spectral effectiveness and large
connectivity (Sun et al 2018) NOMA is regarded as the best
technology in which various NOMA technique exhibit similar
concept of providing several users at the similar frequency and
time The famous NOMA types are code domain and power
domain that provided enhanced efficiency when compared
with the existing techniques The paper adopted the power
domain on the basis of super position coding (transmitter side)
at the SIC (receiver side) Hence the users could possess the
key for the messages of other users and thereby utilize SIC for
removing the interference (Cao et al 2019) (Zhao et al
2018) Hence various NOMA methods was proposed for
allowing the adjacent users to perform as a relay for improving
the efficiency of the weak users through the resending of
decoded data in a next time slot The weak user could utilize
the MRC technique to integrate the information achieved in
different time slots In addition obtaining a secured
communication is a crucial problem over the vulnerable
wireless networks to security threats mainly because of the
broadcasted transmission nature
The study investigated the secrecy performance and outage
with the untrusted user(Furqan et al 2019) The main aspect
of the study is to analyze the feasibility of achieving the OP of
the pair under a trusted user Because of the decoding facility
and spectrum sharing of SIC the untrusted user could perform
as a eavesdropper
Figure 1 Representation of Base station
Figure 1 depicts the representation of base station The main
aim of the proposed system defined as
bull To investigate the outage probability of the proposed
system
bull To investigate the SOP of the proposed system
bull To derive the accurate expression of the outage
probability for all kind of scenarios and closed form of
expressions for few special cases and verifying them
numerically for yielding a better outage efficiency
2 RELATED WORKS This section describes the different existing techniques and
methods related as our proposed system (Cao et al
2019)suggested two kinds of relay selection process denoted
as AF (amplify and forward) and DF (decode and forward) on
the basis of AORS and DORS for achieving secure and
reliable NOMA systems under the untrusted users The study
derived the accurate and asymptotic closed form of the SOP
expressions and the PSCP obtained by the two methods and
investigated the optimized feature of the two methods The
____________________________________
bull PANKAJ M PATEL is currently pursuing PHD program in Electronics
amp Communication in Gujarat Technological University E-mail
pankajmphd24gmailcom
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complete analysis and the simulation results represented that
both the AORS and DORS characteristically outperformed the
benchmark system apart from obtaining the similar SOP and
the required PSCP at very high Signal to noise ratio (Zhang et
al 2018)Investigated the power allocation and joint subcarrier
issue for NOMA ndashAF two-way relay networks with restrictions
The study focused to optimize the obtainable secrecy
efficiency by designing jointly the SC task power allocation
and user pair scheduling The paper suggested a SCAS-1
technique by assuming the appropriate information about the
channel state information in the relay station followed by the
formulation of SCAS-2The secured power allocation issue is
structured as a convex programming issue and then resolved
by in-depth point techniques The results of simulation
explained that the efficiency of the suggested SSPA algorithms
with and without CJ respectively (Arafa et al
2019b)Considered a downlink system where the base station
is connecting with two appropriate users in two various
scenarios in the unsecured environments which are the
presence of the eavesdropper and untrusted relay
communication In the first process several trusted
cooperative relays is engaged for assisting with the base
station transmission and protect the corresponding signals
from the eavesdropper Several relay methods are framed and
investigated for the following process which are forward and
decode cooperative jamming and AFFor all the technique
secured beam forming signals were formulated at the relays
for maximizing the obtainable secret rate areas For the next
process with untrusted relay the obtained secrecy rate areas
obtained for two various relay schemes which are AF and CF
under two various operation modes In the first process the
prescribed users will receive the signals from the untrusted
relay and the base station for decoding the messages The
study depicted that the efficient relay scheme is highly
dependent on the parameters of the system especially the
nodal distance and the secrecy rate area (Sun et al
2018)Studied the algorithm for resource allocation for MISO
systems where the full duplex BS serve several half duplex
downlink and uplink users on the similar subcarrier The
allocation of the resource have been optimized for maximizing
the weight system output whereas the leakage of information
was restricted and an artificial noise was induced for granting
secured communication with respect to potential
eavesdroppers The study formulated a novel non-convex
optimization issue by considering the imperfect CSI of the
channels and requirements of QoS of legitimate users The
simulation results stated the efficiency of the optimal algorithm
was related to the suboptimal algorithm Apart from that the
suggested MISO NOMA technique not only guarantee uplink
and downlink communication purpose for security but delivers
a characteristic rate of system secrecy when compared with
the conventional MISO and other two baseline methods
(Dang et al 2017)Analysed the outage efficiency of various
multicarrier relay selection techniques for 2 hop OFDM system
in Poisson relay fields The study concentrated on DF relay
systems with more selection schemes The accurate
expressions for the OP are provided in integrals generally
Apart from that asymptomatic derivatives for OP in the SNR
region in the fixed circle area are predicted for both relay
selection techniques in closed forms Consequently several
significant factors that are linked to the cooperative network
were examined comprising OP ratio of two selection
techniques diversity and subcarrier optimization output In
conclusion a structure to analyze the OP of OFDM with
spatially random relay have been constructed that could be
easily altered for analyzing same case with various forwarding
protocols channel conditions and location distributors (Dang
et al 2018)Proposed a full duplex OFDM ndashD2D system in two
hop network where DF relays help the transmission from DUE
transmitter to DUE receiver The study also investigated the
OP issue by integrating the transmit power within the DUE
relays and transmitter and to deliver a suboptimal solution that
can improve the outage performance The investigations are
validated by Monte Carlo simulations These results described
could furnish an insight into full duplex OFDM system and
guides for the application in the next generation network
(Kokshoorn et al 2016) suggested a robust channel algorithm
for mmWave systems on the basis of novel overlapped pattern
design With the use of finite measurements the study
depicted that this decreased measurements was found ENR of
25 dB to obtain the similar PEEFor the appropriate channel
with quickly altering channel information the price might be
acceptable for improving the speed of estimation The study
also proposed a robust channel estimation algorithm where
the additional calculations are carried out when expecting
more estimation error The study depicted that the channel
could be measured more effectively resulting in noteworthy
gains upto 6 dB when comparing with the existing algorithm
(Ali et al 2016) described the variations in the principles of
downlink and uplink NOMA transmissions in a wireless
system The study formulated a maximization issue in a cell
like the user clustering and power allocations Because of the
integral nature of the formulated programming issue the study
solved the issue in to steps which are grouping of users into
clusters and then to optimize the corresponding power
allocations The study proposed a sub optimal scheme that
exploited the gain variations in NOMA groups and clusters into
multiple and single clusters for enhancing the sum-throughput
The results compared the efficiency of OMA and NOMA in
different network scenarios (Lv et al 2017) investigated a
MCR-NOMA where the multicast user functions as relays to
enhance the efficiency of both secondary and primary
networks On the basis of the available CSI three various
secondary user schedule techniques for processing MCR-
NOMA were depicted For evaluating the system efficiency the
study derived the closed form of expressions of OP and order
of diversity for both the networks It has been described that
more spatial temporal diversity could be obtained by using the
CSI for scheduling of the secondary user (Liu et al 2016)
considered a MIMO ndashNOMA scenario for investigating a
dynamic clustering issue in an logical perspective To resolve
the problem of optimization issue three algorithms named top
down A and B bottom up were suggested for realizing various
complexity tradeoff and worst user throughput The study
noted that the top down B algorithm could obtain a better
tradeoff between throughput and complexity amongst the
applied procedures (Fianu and Davis 2018) investigated
three various rules of allocation and demonstrated the optimal
policy as an available inventory function The study also
provided the country level estimation of requirements that are
not met and the determination of the probability distribution
linked with the total undeserved counties The study have
been done for depicting the policy of allocation with respect to
effectiveness and equity (Hou et al 2018) studied the socio
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graphical impact on the mobile video services and thereby
suggested a CTMDP on the basis of resource allocation
technique by considering social graphs as the constraints
With the use of relative value an optimized policy could be
achieved that aimed at increasing the reward regarding the
average system The simulation depicted that the suggested
CTMDP obtained an increased efficiency against the state of
art methods
3 PROPOSED WORK
Fig 2 Proposed flow depicting the overall mechanism
The proposed(Interference mitigation using POMDP) overall flow
is depicted in the figure 2 After setting up of the base station the
distance between the base station and the user was determined
and if the distance is less than 200 meters it is decided as trusted
users and if it is greater than 200 m it is defined as untrusted
users In case of untrusted users the channel state information is
subjected to POMDP (Partially observable Markov Decision
Process) followed by resource allocation The performance
analysis have been done after the system The work considered
a NOMA oriented cellular setup provided with a base station at
the centre and two users as shown in the figure 2 The adjacent
(near) user possess high level of security clearance that is
required for securing with physical layer from the low
securityuntrusted clearance user (U2) that is located at a faraway
distance from the base station P is defined as the maximum
transmit power level (base station)In this paper it is assumed that
all the network nodes are installed with single antenna and further
all the channels are considered to be identical independently
quasi static with Rayleigh distribution with respect to distribution
119862119873(0 120575 frasl
120596 frasl
) In which 120575 is the distance in-between the BS
and nodes 119880 Here path-loss exponent and path-loss constant is
represented as 120572 and 120596 In addition it is assumed that base
station predicted the user location so that a better CSI is
obtainable at base station that is involved in pairing the users
The base station transmits the superimposed mixture
119909 = radic119905 119904 + radic1 minus 119905 119904
In which 119904 119904 are the unit power signals received by users 119880 and
119880 respectively 119905 is the power
allocation coefficient for the adjacent user
119903 = ℎ 119909 radic119875 + 119899
119903 = ℎ 119909 radic119875 + 119899
where ℎ ℎ - the channel gain linked with the
small-scale fading from the base station to users 119880 and 119880
respectively 119899 and 119899 are the extra white Gaussian noise with
variance and zero mean 1198730 and it is assumed that 120588 = 1198751198730 is
the BS convey signal-to-noise ratio (SNR) In NOMA technique
farther user that possess more power
could decode its own signal by considering the adjacent signal as
a noise without decoding the adjacent user message In the
preceding equation it is assumed that U1 first decode the weak
signal followed by decoding its own signal with SICU2 which is
the untrusted user attempted to decode the near user message
after the decoding of the adjacent user messages after the
process of decoding its own message with SICHence the
following equation have been achieved
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119879119900119905119886119897 = 119878119868119873119877 119878119868119873119877
119878119868119873119877 119878119868119873119877
+
where 119878119868119873119877 represented the signal-to-interference-plus-noise-
ratio of user 119898 that was decoded by 119880 for 119898119899120598119894 2+ and the
channels gain of 119880 denoted by |ℎ |
followed an exponential distribution
with the parameter 120577 = 120596 120575
Problem Formulation
Hence the base station should achieve and serve a better
communication for the users who are susceptible to security
threat from untrusted user the proposed system defined two
kinds of QoS efficiency measures that could be regarded to be
important for framing the issue In specific the study defined a pair
of OP to check the reliability of the QoS satisfaction In general
the pair OP is stated as the probability in which the obtainable
data rates dor the users equal to or greater than the least target
threshold The next metric also called as the SOP is the
probability that the non negative secrecy capacity obtained by the
trusted user is more than the threshold value
The following issue aimed at reducing the pair OP subjected to a
SOP factor for the user U1 that is provided by
min
119875
0 lt 119905 lt 05
119878119874119875 le 120573
in which 119875 119878119874119875 and 120573 are the pair OP SOP(119880 ) and the
permissible SOP threshold
4 PERFORMANCE ANALYSIS
Derivation of the Pair OP
With the use of Shannonrsquos capacity formula and considering
119862 and 119862
as the threshold capacities of users 119880 and
user 119880 respectively the OP of the pair could be provided
by
119875 = 1 minus 119876 119909119876
in which
120591 = 2
119898 120598 119894 2+
120601 =
( )
120601 =
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119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 1 120601 gt 120601
For having 120601 gt 120601 the constraint on
the power allocation factor (t) needs to be satisfied
(119905 gt
) and for this case 119876 could be obtained as
follows
119876 = exp (
)
lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 2 120601 lt 120601
Like case 1 it was stated that opposite constraint on
a as (119905 lt
) and
119876 can be derived as follows
119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
The OP of the NOMA pair
119875 = 1 minus 119891(119905)119896 (119905)
lt 119905 lt
1 minus 119891(119905)119896 (119905) 0 lt 119905 lt
in which
119891(119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
Derivation of SOP of 119880
With Shannonrsquos capacity formula the secrecy rate of
user 119880 was provided by
119878119862 = 119869 minus 119869
119869 = log (1 + 119879119900119905119886119897 (r (1)))
119869 = log (1 + 119879119900119905119886119897 (r (2)))
119878119862 is the non-negative secrecy capacity of 119880 Provided the
secrecy capacity in the SOP of 119880 is
119878119874119875 = 1 minus 120584119890
119860 =
120584 =
119879 - the user 119880 secrecy target rate
Theorem 1
Outage-optimal power allocation factor
119905 = radic
( )
In which 119908 =
119908 =
119911 = 1 + 120591
The minimum power allocation factor (119886 )
119905 =
(
)
The optimal OP of the NOMA pair under the SOP constraint
=
( )
( ( ))119890
( )
That is lt 0whih meant that the U1 (SOP) is a reducing function
Of t that results in the optimal power allocation factor that is
greater than 119905 for the satisfaction of secrecy constraining
factorPartially observable Markov decision process S is
represented as statesLet D is the channel features which is
consider here as actions the conditional transition probability
between states is regarded as T Reward function R is
calculated as the prediction of maximum capacity channel with
respect to data rate r = R(S x D) the agent receives an
observation o ϵ 120118 o isin Ω display style oin Omega that
depended on the new environment state S and on the just
took action d with the probability O(o|s d)
Reward received at time t is conveyed as r = R(S x D)
H is the belief states over POMDP states
119867 is the belief state transition function
119903 = 119877(119867 x 119863) is the reward function on the belief states
119861 (ℎ 119889 ℎ ) = sum Pr ( 120118 ℎ |ℎ 119889 119900) Pr(119900|119889 ℎ)
Pr(h |h d o) =
1 if the belief update with arguments h d o returns h 0 otherwise
The reward function is updated on the basis of the belief MDP
r (h d) = sum h(s) R(s d) isin
the agent focus on the largest expected immediate rewardin
other words the maximum capacity channel The section
analyse the accuracy of the analytical derivations under
various settings
Figure 3 The feasible pairing
The SOP of U1 with the increasing untrusted user U2 and
distance (d2) for several BS transmits Signal to Noise Ratio
at 120588 = minus20minus1020 119889119861is depicted in with a=005 and 01 and
d1=200m is depicted in the figure The results stated that the
U1(SOP) is a gradually reducing function as per d2 that
implies that the increasing value of d2 leads to the
improvement of the SOP of U1 Since the provided constant
threshold ϵ in SOP restraint U2must be situated at a larger
space when compared with threshold value to obtain the SOP
of U1 Apart from that it is normal that the high the target
secrecy rate rises the SOP of U1
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Figure 4 The Secrecy outage probability
Feasible Pairing in th SOP of pair OP and U1 with the
enhanced power allocation factor (a) in which d2 = 700 m d1
= 200 m 120588 = 15 dB and ϵ = 01 The results depicted that the
the pair OP and SOP of user U1 with increased a for two (d2)
various distances of the (U2) untrusted user The results
approve the convex nature of the pair OP and the SOP curve
is gradually decreasing on the basis of a Generally during the
increase in a the power assigned to the weak user message
decreases that minimize the ability of U2 for discriminating the
superior positioned signals thereby improving the SOP of U1
Figure 5 The Pair outage probability
Pair OP in case of rising U2 untrusted user in distance (d2)
for different base station transfer the signal to noise ratio(120588 =
5 15 25 dB) where a = 015 and d1 = 200 m
Figure 6The infeasible pairing of secrecy outage
probability of the pair OP and U1
The infeasible pairing of SOP (U1) and the pair outage
probability with the enhanced allocation of the power ad1(200
m)d2(300 m)120588 = 15dB and ϵ = 0
The figure 6 depicted that the
The figure 6 shows the similar plotting of the data by altering
the untrusted user location by transferring it to a BS closer
distance (d2 = 300 m) It also depicted that the U1 SOP
constraint of is disrupted at a because the SOP is more than ϵ
The accuracy is well-matched and verified with all range of
numerical simulation The results noticed that the efficiency is
based on the comparative locations of the two user with the
base station
Figure 7 The figure 7 depicts that SNR versus strictly
positive secrecy rate
The observed graph proves that the secrecy capacity
outperforms the existing techniques The proposed precoding
application increases the performance of the system The
transmission power of the system is the power required to
transmit a particular data When there is an increase in the
number of users there is the possibility of inference in the data
transmission and hence the efficiency of the data rate may be
affected Depending on these instances the efficiency of the
antenna capacity to withheld and accommodate the data
determined
Figure 8 The power radiated by BS antenna
In the figure 8with respect to the simulation setup the
precoding methods are performed based on the radiated
power per BS antenna is depicted The results observed the
better efficiency of the proposed system The proposed proves
to be better when compared with existing linear precoding
methods in the prescribed three metrics thereby stating that
MRT may be utilized for the the examination of the secrecy
capacity Our proposed technique spends less radiatated
power thereby increasing the overall capacity of the system
5 CONCLUSION The NOMA system decodes the messages of other user pairs
on the similar resources thereby promoting user possibility
The technique interprests a security threat in which the BS
serves the untrusted users The study analysed the SOP and
OP in both multi user and two user NOMA system in which the
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base station pairs the trusted user in closed type of
expressions The proposed (Interference mitigation using
POMDP) also enable the understanding of possibility of
achieving outage optimal efficiency to pair under SOP
constraints The numerical verifications verified the efficiency
of the analytical derivations
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Dynamic user clustering and power allocation for
uplink and downlink non-orthogonal multiple access
(NOMA) systems IEEE access 4 6325-6343
[2] ARAFA A SHIN W VAEZI M amp POOR H V
2019a Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
15 210-222
[3] ARAFA A SHIN W VAEZI M amp POOR H V
2019b Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
[4] CAO K WANG B DING H LI T amp GONG F
2019 Optimal Relay Selection for Secure NOMA
Systems under Untrusted Users IEEE Transactions
on Vehicular Technology
[5] DANG S CHEN G amp COON J P 2018
Multicarrier relay selection for full-duplex relay-
assisted OFDM D2D systems IEEE Transactions on
Vehicular Technology 67 7204-7218
[6] DANG S COON J P amp CHEN G 2017 Outage
performance of two-hop OFDM systems with
spatially random decode-and-forward relays IEEE
Access 5 27514-27524
[7] FIANU S amp DAVIS L B 2018 A Markov decision
process model for equitable distribution of supplies
under uncertainty European Journal of Operational
Research 264 1101-1115
[8] FURQAN H M HAMAMREH J amp ARSLAN H
2019 Physical Layer Security for NOMA
Requirements Merits Challenges and
Recommendations arXiv preprint arXiv190505064
[9] HOU L ZHENG K CHATZIMISIOS P amp FENG Y
2018 A Continuous-Time Markov decision process-
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for mobile video services Computer
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[10] KOKSHOORN M CHEN H WANG P LI Y amp
VUCETIC B 2016 Millimeter wave MIMO channel
estimation using overlapped beam patterns and rate
adaptation IEEE Transactions on Signal Processing
65 601-616
[11] LIU Y ELKASHLAN M DING Z amp
KARAGIANNIDIS G K 2016 Fairness of user
clustering in MIMO non-orthogonal multiple access
systems IEEE Communications Letters 20 1465-
1468
[12] LV L CHEN J NI Q amp DING Z 2017 Design of
cooperative non-orthogonal multicast cognitive
multiple access for 5G systems User scheduling and
performance analysis IEEE Transactions on
Communications 65 2641-2656
[13] SUN Y NG D W K ZHU J amp SCHOBER R
2018 Robust and secure resource allocation for full-
duplex MISO multicarrier NOMA systems IEEE
Transactions on Communications 66 4119-4137
[14] ZHANG H YANG N LONG K PAN M
KARAGIANNIDIS G K amp LEUNG V C 2018
Secure communications in NOMA system
Subcarrier assignment and power allocation IEEE
Journal on Selected Areas in Communications 36
1441-1452
[15] ZHAO T LI G ZHANG G amp ZHANG C-X
Security-Enhanced User Pairing for MISO-NOMA
Downlink Transmission 2018 IEEE Global
Communications Conference (GLOBECOM) 2018
IEEE 1-6
132
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1
PhD THESIS Non-Exclusive License to
GUJARAT TECHNOLOGICAL UNIVERSITY
In consideration of being a PhD Research Scholar at GTU and in the interests of the
facilitation of research at GTU and elsewhere I Pankaj Manubhai Patel has Enrollment
No139997111012 hereby grants a non-exclusive royalty-free and perpetual license to
GTU on the following terms
a) GTU is permitted to archive reproduce and distribute my thesis in whole or in part
andor my abstract in whole or in part (referred to collectively as the ldquoWorkrdquo) anywhere
in the world for non-commercial purposes in all forms of media
b) GTU is permitted to authorize sub-lease sub-contract or procure any of the acts
mentioned in paragraph (a)
c) GTU is authorized to submit the Work at any National International Library under
the authority of their ldquoThesis Non-Exclusive Licenserdquo
d) The Universal Copyright Notice (copy) shall appear on all copies made under the authority
of this license e) I undertake to submit my thesis through my University to any Library
and Archives Any abstract submitted with the thesis will be considered to form part of
the thesis
f) I represent that my thesis is my original work does not infringe any rights of others
including privacy rights and that I have the right to make the grant conferred by this
nonexclusive license
g) If third party copyrighted material was included in my thesis for which under the terms
of the Copyright Act written permission from the copyright owners is required I have
obtained such permission from the copyright owners to do the acts mentioned in paragraph
(a) above for the full term of copyright protection
h) I retain copyright ownership and moral rights in my thesis and may deal with the
copyright in my thesis in any way consistent with the rights granted by me to my
university in this non-exclusive license
i) I further promise to inform any person to whom I may hereafter assign or license my
copyright in my thesis of the rights granted by me to my university in this non-exclusive
license
j) I am aware of and agree to accept the conditions and regulations of a PhD including
all policy matters related to authorship and plagiarism
Signature of the Research Scholar
Name of Research Scholar Pankaj Manubhai Patel Date 17092021
Place Ahmedabad
Signature of Supervisor
Name of Supervisor Dr Chetan B Bhatt Date 17092021
Place Ahmedabad
Seal
i
ABSTRACT
The landscape of future fifth-generation (5G) radio access networks is
expected to seamlessly and ubiquitously connect everything and
support higher traffic volumes densely connected wireless devices and
diversified requirements on reliability latency battery lifetime etc as
opposed to the current fourth-generation (4G) cellular networks
Moreover in unexpected or emergencies (such as disaster relief and
service recovery) the deployment of terrestrial infrastructures is
economically infeasible and challenging due to high operational
expenditure as well as sophisticated and volatile environments To
address such novel issues intelligent heterogeneous architecture by
leveraging unmanned aerial vehicles (UAVs) (or commonly known as
drones) has been considered to be a promising new paradigm To
improve the system performance of UAV communication in 5G
networks physical layer techniques are of much concern as they affect
the applications of UAVs significantly In this research work security
aspects of NOMA-based UAV communication network have been
considered for optimization as physical layer security in a wireless
communication network is not as robust as wired communication due to
fading and varying SNR scenarios Here primarily two usersrsquo models
as the trusted and untrusted user communicating with BS have been
optimized for outage-optimal performance considering pair Outage
probability and Secrecy outage probability as performance metrics The
achieved results are extended to multi-user scenarios also and for the
optimal policymaking dynamic programming and Partially Observable
Markov Decision Process (POMDP) optimization approaches have
ii
been simulated and verified The simulated results have shown that
POMDP has potential consideration as a resource scheduling
optimization technique in the NOMA-UAV communication network for
providing secure and more robust performance
iii
Acknowledgment
Completing a PhD is a tough task that requires hard work and a lot of effort This is
often an overwhelming but also great experience that I would not have been able to
complete without the assistance and support of so many people Thus it is my great
pleasure to thank all those people First of all I would like to thank almighty for giving
me the strength to carry out this task I would like to deeply thank Dr Chetan B Bhatt
my supervisor for his guidance encouragement and support over these years This
research work would not have been possible without his constructive pieces of advice his
systematic guidance and his patient support thought out the duration of my research work
I would like to express my sincere gratitude to Dr Harshal A ALOORKAR and Dr
KIRAN R TRIVEDI Dr Mehul Raval my doctoral progress committee members Their
rigorous style of reviewing and constructive feedback with valuable suggestions of Dr
Prakash Gajjar Mr Hitesh Panchal and Mrs Monali Mandli who spent their valuable
time whenever required for discussing aspects of this work and provided relevant material
as well Mr Parth Modi and Mr Jagadish Patankar to initiate and inspired me a lot to
continue my work Mr Mukesh Sharma who help in maintain documents I am also
thankful to my parents and family members who always stood with me in each critical
situation and supported me endlessly I am thankful to all EC departments of various
polytechnic and degree engineer colleges for their cooperation in every possible means
Lastly I would thank all the people who directly or indirectly helped me during this very
important phase of my life
Pankaj Manubhai Patel
vi
List of Abbreviation
3GPP 3rd Generation Partnership Project
5G Fifth Generation
A2G Air to Ground
AWGN Additive White Gaussian Noise
BDM Bit Division Multiplexing
BS Base Station
BPCU Bits Per Channel Use
CDMA Code Division Multiple Access
CR Cognitive Radio
CSI Channel State Information
CNPC Control and Non-Payload Communications
CRN Cognitive Radio Networks
D2D Device-to-Device
DCP Difference of Concave Programing
DOMP Dynamic Optimization Method of Programming
FR Floating Relay
GSM Global System for Mobile Communications
HLPSL High-Level Protocol Specification Language
ICT Information and Communication Technology
IoT Internet of Things
IRS Intelligent Reflecting Surface
IMT Information Management Technology
vi
LDS Low-Density Spreading
LTE Long Term Evolution
LTE-A Long Term Evolution Advance
MCR Multicast Cognitive Radio
MI Mobile Internet
MIMO Massive Multiple-Input Multiple-Output
mm-Wave millimeter Wave
MTC Machine-Type Communication
MUSA Multi-User Mutual Access
NOMA Non-Orthogonal Multiple Access
OFDMA Orthogonal Frequency Division Multiple Access
OMA Orthogonal Multiple Access
OP Outage Probability
POMDP Partially Observable Markov Decision Process
PLS Physical Layer Security
PDMA Pattern Division Multiplexing Control
PUN Primary User Networks
QoS Quality of Service
RIS Reconfigurable Intelligent Surface
RNRF Random Near-Random Far
Rs Target Secrecy Rate
SAGIN Space-Air-Ground Integrated Networks
SIC Successive Interference Cancellation
STBC Space-Time Block Coding
vi
SBF Secrecy Beam Forming
SCMA Sparse Code Multiple Access
SOP Secrecy Outage Probability
TAS Transmit Antenna Selection
TDMA Time Division Multiple Access
UAVC Unmanned Aerial Vehicle Communication
UMTS Universal Mobile Telecommunication Systems
URLLC Ultra-Reliable Low Latency Communication
vii
List of Figures
Figure Title Page
No
11 Usage of wireless sensor network and UAV in the
hazardous disaster control
6
12 UAV network applications types with security services
architecture
8
13 UAV-assisted heterogeneous network architecture 12
14 Security problems in the UAV 15
15 Comparative analysis of NOMA vrsquos OMA 18
21 Vehicular communication NOMA system 28
22 RS-NOMA against an external eavesdropper 31
31 Downlink NOMA network 44
32 Uplink NOMA network 46
33 Multi-two user architecture of NOMA system 49
34 Flow Diagram of the proposed system 50
35 Near and Far User 51
41 Impact on Sop with increase distance between BS and user U2 60
42 Impact on Sop with increase distance between BS and user U2 61
43 Feasible pairing t Vs pair OP 61
44 Infeasible pairing t Vs pair OP 62
45 Secrecy outage probability 63
46 Pair outage probability 63
47 SNR versus Strictly positive secrecy rate 64
48 Power radiated by per MMBs antenna 64
viii
List of Tables
Table Title Page
No
11 Physical layer hazards and measures in UAV wireless
communication network
13
21 Comparative analysis 33
31 List of parameters59 54
41 Simulation parameters 59
ix
Table of Content
Sr
No
Title Page
No
I Abstract I
II Acknowledgment II
III List of Abbreviation III
IV List of Figures Iv
V List of tables V
1 Introduction 1
11 Modern technology and its needs 1
111 Long term evolution of 4G network 2
112 Migration from 4G LTE to 5G for UAV communication 3
12 UAV assisted communication in heterogenous sensor network 5
121 Introduction to UAV Communication network 7
122 Tyews of UAVs 8
1221 UAVs as flying BSs 8
1222 UAVs as aerial UBs 10
13 Unmanned aerial vehicle for 5G network 11
14 Physical layer insecurity in UAV communication network 12
141 Principles of security 13
15 Non-Orthogonal Multiple Access (NOMA) system secured
communication
16
151 Comparison of NOMA Vs OMA 16
1511 Spectral throughput and efficiency 17
1512 User fairness and higher lately 17
1513 Compatibility 17
16 Problem identification 18
17 Motivation 19
18 Aim and objective of the research 20
19 Thesis organization 21
2 Literature review 23
x
21 Integration of UAV Networks for 5G and B5G communication 23
22 UAV-NOMA in physical layer security enhancement 26
23 Research methodology 38
24 Summary 39
3 System model for NOMA-UAV communication 41
31 NOMA -UAV system secured communication for 5G 41
311 The basic scheme of NOMA 41
312 Downlink of NOMA 44
313 Uplink of NOMA 46
314 Comparison of NOMA and OMA 47
32 PLS performance metrics in NOMA -UAV communication 47
321 SOP and OP - two user and multi-user NOMA system 48
322 System Model 48
323 Partially Observable Markov Decision Process-POMDP 50
324 Problem formulation 52
33 Performance Analysis Improving PLS Insecurity of NOMA
System
53
331 The pair OP calculation 53
332 Pseudo-code for the proposed algorithm 55
34 Summary 57
4 Result and discussion 58
41 Performance measure of secured NOMA-UAV communication
model
58
42 Numerical result and discussion 59
421 Feasible amp Infeasible pairing of trusted amp untrusted
users
60
422 The secrecy outage probability and pair outage
probability
62
423 SNR versus strictly positive secrecy rate 63
424 Power radiated by per MMBs antenna
64
43 Conclusion and scope of future work 65
431 Conclusion 65
432 Future scope 66
xi
5 References 67
8
Publications 78
1
CHAPTER -1
INTRODUCTION
11 Modern technology and its needs
Mobile technology has undergone various generational shifts transforming the
cellular framework into a worldwide set of interconnected networks In recent days
the fifth generation (5G) has delivered voice as well as video streaming It has a
very complex range of networking services for more than nine billion users and also
billions of devices that will be connected (Hu 2016) However 5G offers a new
outlet for reflection It involves a radial network architecture for the installation of
communication-type machines 5G network can also include powerful support
applications with widely varying operating parameters 5G is a blend of network
technologies that have been developed The new 5G technology will be able to
exchange information anywhere every time for the benefit of people enterprise
and society and technical environments using a restricted access bandwidth to
carry data Now it is more than a modern series of technologies and as opposed to
previous generations would entail tremendous infrastructure or machinery
upgrades This technology aims to expand on the advances that telecommunications
systems have already achieved The projected standards of efficiency that
technologies would need to resolve are
bull Five times reduce end-end latency
bull Ten to a hundred times the higher complex rate of user data
bull Battery life is ten times longer
bull 10 to 100 times higher number of connected devices
In this research work the UAV-assisted communication over the 5G network has
been proposed with enhanced physical layer security aspects NOMA has been
proposed as the reference framework architecture for UAV communication as one
of the recent popular 5G techniques Along with the advantage of suitability in UAV
communication network NOMA has the disadvantage of insecurity in the physical
layer Here the migration of Long Term Evolution (LTE) to advanced physical layer
2
security for Unmanned Aerial Vehicle communication (UAV) over 5G network has
been proposed and also improve the insecurity of Non-Orthogonal Multiple Access
(NOMA) System We will discuss in the further chapter the proposed work This
chapter describes the introduction and basic concepts of the 5G networks with
methodology techniques and types It states the problem identification motivation
and further aim and objective of this work
111 Long Term Evolution of 4G Network
LTE is customary for 4G wireless broadband trends that provide improved network
capability and gives mobile device users speed It offers high peak data transform
rates in the range of 100 Mbps and 30 Mbps downstream and upstream
respectively It provides a capacity of scalable bandwidth mitigated latency and
backward compatibility with the previous Global System for Mobile
Communications (GSM) and Universal Mobile Telecommunication Systems
(UMTS) technology
The fourth development of cellular networks (4G) has already been developed to
meet the standards of the 3G and 2G families Every 10th year a new mobile
generation claimed to be familiarized with the first 1G system in 1981 tracked by
the 2G system that went on to roll out in 1992 and 3G launched in 2001 growth in
the year 2002 of 4G networks The actual new revolution began in December 1998
with the 3rd Generation Partnership Project (3GPP) With high-quality video and
images 3G networks are designed for multimedia networking with them Peoples
communication can also be enhanced and connectivity to public and private
network information and resources has improved with higher frequencies and new
flexible communication features third-party device applications
With the start of LTE-Advanced several vital demands and improvements are
beginning to emerge Various importance purposed for LTE-Advanced can be
exemplified as follows (Abed)
bull Provides spectrum output with LTE delivered more than three times
bull Spectrum can help scalable bandwidth and convergence of the spectrum
where it is necessary to use a non-contiguous range
3
bull Provides uplink and downlink spectrum output that varies between
15bpsHz and 30bpsHz
bull The edge throughput must be twice that of the user cell in LTE
bull From idle status to connected status the communication latency scenario is
smaller than 50msec and less than 5msec for direct packet transfer
bull Any users total throughput must be three times that of LTE
bull LTE advancement will provide 3GPP as well as LTE compatibility via inter
networking
bull The mobility conditions that are used in LTE are identical
The latest LTE advanced requirements are not yet included in device
specifications there are high-level purposes Before it is fixed in the specifications
and needs to be tested much effort remains to be approved
112 Migration from 4G LTE to 5G for UAV communication
The productive implementation of a UAV communication network in 4G and the
upcoming wireless network is included in identifying combined solutions to test
the correlation with both multitudes and also energy-efficient transmission Then
the process of the UAV-BS to optimize coverage and power It is stated that the
energy efficiency of the UAV-aided communication system is needed Efficient
energy utilization contributes to increased air time in the contact system and
increased joulesbits at a provided energy level Also aerial cell coverage and
ability may be because of various parameters such as antenna gains transmission
strength radio access technology UAV altitude and deployment environment
4G is the fourth generation of network infrastructure technologies to replace 3G and
in addition to the popular 3G4G methods Code Division Multiple Access
(CDMA) Time Division Multiple Access (TDMA) and Orthogonal Frequency
Division Multiple Access (OFDMA) Researchers are designing the latest Non-
Orthogonal Multiple Access (NOMA) technologies to be used because of their
capability to improve the performance of communication networks Non-
4
orthogonality-based device designs have recently been developed for use in
communication networks and drawn considerable interest from researchers
Henceforth Multiple Access (MA) methods can be sub-divided as OMA and
NOMA Each user may utilize orthogonal communication resources to determine
multiple access interference inside a frequency band code and time slot in OMA
Its methods such as First generation (1G)- FDMA 2G -TDMA 3G -CDMA and
4G - OFDMA have been used in previous network generations In NOMA by
producing a higher spectral efficiency however enabling some amount of multiple
entree intrusion in receivers and multiple users may use non-orthogonal resources
simultaneously Recently the credibility of NOMA as a solution to the problems of
the next generation of wireless networks has been increased Compared with OMA
technologies NOMA has been described to improve spectral quality be well-
adjusted with air connectivity and can provide accommodations for multiple
strategies at the same time of frequency Therefore enabling excellent progress to
massively correlated devices
In particular NOMA also affects mitigating interference by using OFDMA as an
orthogonal method or through offering a standard intra-cluster access beam across
multiple users and inter-cluster access in NOMA Recent studies have concentrated
primarily on the provision of Air to Ground (A2G) connectivity services through
optimization of a different point of view
The output of the UAV-based communication network was discussed in the Device
to Device (D2D) implementation setup The proposed system hypothesized
interference caused through D2D network nodes deprived of acknowledging the
occurrence of global BS Also several studies addressed the efficiency of NOMA
It permitted the deployment of fixed-wing to assist coverage in-ground user located
outer location of offloaded BS
NOMA systems are divided into two categories namely code domain and power
domain multiplexing In the power domain user accounts are allocated to different
power coefficients as per their channel complaint to reach optimal device
efficiency Multiple user signals are applied to the side of the sender Then on the
received signal Successive Interference Cancellation (SIC) is implemented to
decipher signals in sequential order until the predicted signal is achieved offering
5
a good trade-off between efficiency of the system and user fairness Different code
domain multiplexing is Sparse Code Multiple Access (SCMA) Low-Density
Spreading (LDS) and Multi-User Mutual Access (MUSA) Compared to power and
code domain multiplexing there are alternate NOMA techniques such as Bit
Division Multiplexing (BDM) and Pattern Division Multiplexing Control (PDMA)
However this multiplexing is capable of improving the efficacy of spectral It
requires a large transfer of bandwidth which is not appropriate for new methods
But on the other side the power domain has direct execution since there is no need
for significant improvements to the current networks It also does not necessitate
bandwidth to increase spectral efficiency In this chapter the main emphasis
depends on the power domain NOMA While OMA strategies can produce the best
results also with necessary receivers due to no mutual intervention among users in
an optimal situation they cannot even resolve increasing problems due to growing
demands on connectivity growth and even beyond
12 UAV assisted communication in heterogeneous sensor network
Wireless communications had created a golden chance for urban and rural
territories The LTE (Long term evolution) and LTE-A (Long term evolution
Advance) had offered the service (with QoS) for all customers through wireless
The traffic properties in the machine type communications (MTC) and the
accumulation of the MI (Mobile Internet) had made the difficulty of implementing
the cellular communication networks Installing base stations was impractical in the
urban areas due to its cost To overcome this issue the UAV suggested that it
contains the merits of compatibility and high battery life and is affordable Most of
the devices like the sensor nodes and professional cameras had been used in UAV-
assisted networks Here the UAV-assisted floating relay (FR) was launched in the
cellular communication networks UAVs were implemented more with WSN
(wireless sensor networks) The base stations were adopted with the UAV So the
MI and MTC traffic challenges were controlled (Yue Li amp Cai 2017)
UAV-assisted Heterogeneous networks had implemented in vast practical
applications UAV helped heterogeneous networks were applied in the military
department In the military the UAV had examined and surveyed the opposing
6
countryrsquos activities for security The UAV-based heterogeneous networks were
used in the military sectors where a novel authentication scheme was introduced
As The one-to-one communication via WSN was considered as secured
communication WSN had the disadvantage of consuming power The
authentication was implemented in the tool of Automated Validation
of Internet Security Protocols and Applications (AVISPA) in which the expression
had been written in the High-Level Protocol Specification Language (HLPSL)
programming language The authentication had evaluated between the user and the
base station Similarly the authentication between the user and the UAV was
calibrated The citizen and economic safety are predicted and conserved through
reliable communication in the military by obtaining foes exploration information
The faithful secured communication was confirmed using AVISPA (Rashid et al
2019)
Figure 11 Usage of wireless sensor network and UAV in the hazardous
disaster control
The integration of the wireless sensor networks and the unmanned aerial vehicle
UAV was analyzed and applied to manage the natural disaster illustrated in Figure
11 The aircraft can prevent the fire spreading drop sensors the temperature map
and biodiversity map by sensors the wildfire can easily route The wild animals can
7
be tracked and the dynamic data of moving animals can be gathered by WSNs The
biologists can fix the sensor in the animals collar the radiation that positively
affects humans can be observed in affected areas The WSNs help to prevent heart
attack of a person by monitoring heart rate The state of health can be known
through a message alarm using a GPRS system
The cooperative networks of WSN and UAV were implemented in the military
sector for the advantageous feature The UAV was providing good connections
overlapping and overall data rate The conventional UAV method aided sensor
networks concentrated only on the single tasks of monitoring accumulating
information and localization The multi-UAV had not been implemented in the
sensor networks The animal colony perception technique was utilized for
scheduling the resourced and the target assignment Functions of multi-data were
used for localization by the target recognition method (Gu Su et al 2018)
The Physical Layer Security (PLS) was achieved through 5G technologies delicate
coding for the PLS dense MIMO multi-input multi-output mm-Wave frequency
band using heterogeneous sensor networks NOMA and full-duplex mode of
communication IoT and Machine-type communications (MTC) emerged in the 5G
systems (Wu et al 2018)
121 Introduction to UAV communication network
The usage of the UAV will develop more in the next era These pre-programmed
aircraft are intended for applications in several civil settings as well as industrial
visualization agriculture rescue and search and then receiving of scientific data
These devices are called the unsuccessful inaccuracy of drones which must be
incorporated into the system of national airspace as well as worldwide The usage
of UAVs in the neutral form is always secure It has a direct inference for the control
and a payload communication system that is utilized to function effectively
Similarly surveillance and navigation operations must be made more accurate and
consistent Due to these critical factors many kinds of research in a UAV testing
development and standardization difficulties are undergone through industries
education and governments
8
Even though civil aircraft had been operating for many years yet UAV offers new
consequences in terms of various flight profiles For example high dynamic
maneuvers and low elevation flights need bandwidth video and different ground
site characteristics namely clutter locations and elevation antennas which are low
This chapter explains the core topic of the proposed work The migration of LTE
4G towards the advanced one of the physical layers for UAV communication It has
higher mobility and lower expense identified in a broad range of applications
122 Types of UAVs
The UAVs have a two-network application with security services such as UAVs as
Flying Base Stations (BSs) and UAVs as Aerial BSs in the presence of
eavesdroppers
(a) UAVs as Flying BSs (b) UAVs as Aerial mobile UEs
Figure 12 UAV network applications types with security services
architecture
1221 UAVs as flying BSs
The required infrastructure can be destroyed in natural disasters particularly
tsunamis earthquakes and snowstorms and the requisite emergency data traffic
cause both overloading and congestion of neighboring mm-Wave (Zeng et al
2016) A capable explanation is to rapidly introduce low-altitude UAVs as flying
9
BSs in such a network breakdown to improve the communication infrastructure to
mitigate cell congestion or site failure thus creating a small aerial cell
In this situation wireless communications can occur in an ad-hoc manner with
UAVs to UEs UAVs to UAVs As highlighted in Figure-12 (a) and control
stations of UAVs to ground It will increase capability dramatically and enlarge the
target of wireless networks in provisional measures as it is possible to create LoS
communication links among UAVs and UEs supported on the ground Yet form an
operating aerial cell system to monitor ground segments of UEs mobility which is
more stable to minimize sporadic connectivity on the other side
Also this can be expanded to allow several UAVs-BSs to be deployed to increase
the exposure area for supporting a wide range of UEs A network period various
UAVs-BSs is entirely independent A new paradigm was introduced through
collaboration between UAVs-BSs to extend the feasibility for a single UAV from
either a stand-alone active sensor to a wireless network over the next generation
There is a growing concern about the privacy problem in tandem with the brief
introduction of this network Wireless protection is the central issue of the
communication level wherever eavesdropping subsidizes for deliberately listening
to a source of secret information which harms the extensive placement of UAV-
BSs
A UAV-BSs is to mount several antennas in the UAV-BSs the benefits of multi-
antenna innovations geographical degree of freedom that offers an ability for UAV-
BSs to transmit eavesdropping airborne beams
Notice that in UAV systems multi-antenna technology can be technically applied
while directly modifying the separation of the antennas The existing system has
shown that transmitted beam forming models can significantly boost the
confidentiality efficiency of wiretap channels for multiple antenna transmitters
Noise may be inserted with the signal to substantially degrade the acknowledged
SINR at the eavesdroppers to prevent the information overflow
10
1222 UAVs as aerial UEs
This has already been demonstrated by reaping the benefits of Wi-Fi and LTE
technologies through field trials (Van der Bergh et al 2016) UAV-UEs typically
get their tasks for a variety of convincing IoT applications mainly in air freight
services like the google wing project Unlike conventional land base package
delivery but UAV delivery has distinctive merits such as
bull Acceleration of land transport as UAVs are not liable to road jams
bull Connection to areas that are difficult to reach
bull Decreasing the use of capital about workforce and electricity
UAV distribution is significantly dependent on having reliable and secure wireless
communication among UAVs and ground BSs especially if the UAV needs control
outside LoS the UAV-UEs are used which can develop LoS connectivity to cellular
BSs The UAV-UEs on the one hand provides high-speed access to data as it can
fly continuously in either direction On the other hand the installation of UAV-UEs
can lead to significant interference with the ground BSs in the execution of their
missions
A wide-scale installation of UAV-UEs is only feasible for this reason if the issues
of interference management are tackled It is widely known that interference
negatively affects wireless networks As highlighted in Figure-12 (b) indeed aerial
and ground UEs are served through a cellular network with a possible eavesdropper
that tries to intercept the message intended for permissible basic UEs
A cost-effective approach is to be used for coordination among ground BS and
UAVs to enhance secure transmission which is part of the UAVs acting as friendly
transmitters to degrade the wiretapping channels efficiency and thus enhance
secrecy efficiency A UAV acting as a mobile jammer can dramatically and
dynamically change its position as near as possible to the earth eavesdropper and
distribute them by sending the radio signals whereas strong LOS connection
characteristics are a beneficial feature with less earthly fading and shadowing
impairment
11
13 Unmanned Aerial Vehicle for 5G Networks
UAVs have technologically advanced as a revolutionary movement in delivering
pervasive connectivity from either the platforms of the sky as aerial
communication particularly for temporary User Equipment (UEs) (B Li et al
2019) Due to fully controllable UAV flexibility through miniaturization as well as
continuous cost reduction low-altitude UAVs are rapid and flexible designed for
operation and reconfiguration They are probable to have higher Line-of-Sight
(LoS) ties to ground UEs
A broad range of applications like inspection of infrastructure precision farming
and disaster area monitoring is becoming accessible in this aspect Moreover
further projects have also been set up to employ aerial platforms for broadband
access to distant elements such as the Google Loon and the Facebook Drone Project
to mention Highly populated UEs are desperate for broadband wireless
communications with the coming 5G period and network providers are supposed
to maintain numerous networks with high demands for wireless data like
multimedia streaming and also video downloads The relentless growth in the
amount of traffic of mobile networks puts a burden on operators in the form of
higher capital and operational expenditure Deploying small cell networks is an
intuitive alternative to outsource cellular traffic
Although in unforeseen or temporary events as mobile environments are
complicated volatile and heterogeneous the implementation of terrestrial
infrastructures is difficult The accessibility of aerial access points to enable
extensive complex connections is one possible solution However in unforeseen or
temporary events as mobile environments are complicated volatile and
heterogeneous the implementation of terrestrial infrastructures is difficult The
accessibility of aerial access points to enable extensive complex connections is one
possible solution UAV communication performance benefits from the simplicity
of the compact transceiver and progressive control methods that obtain broad
exposure and set up internet networks
12
Figure 13 UAV-assisted heterogeneous network architecture
The above Figure 13 is depicted to build flexibility of the network with enhanced
ability and elasticity It is a good network that offers security endowment This is
due to the transmitting information to UAV communication which is tapped
through ground unauthorized user and is known as an eavesdropper
Here through eavesdropper based on the upper layer cryptographic techniques
wireless communication in contradiction of unauthorized access has been protected
However it is very tough to achieve because of key management as well as more
computational difficulties in developing network architecture PLS affects the
characteristics of intrinsic wireless networks as a fascinating preparation such as
interference noise fading loss collecting signal characteristics in malicious
eavesdroppers and techniques of signal processing
14 Physical Layer Insecurity in UAV communication network
Jamming is either a well-defined WSN attack on a physical layer It disrupts the
radio waves being used by nodes of the network The attacker successively
expresses the denial of the simple MAC protocol over the wireless network The
impressive network can be disrupted at which a single frequency is being used
13
throughout a network (Modares et al 2011) In addition jamming can increase
energy consumption in the node by inserting impudent packets The receiver nodes
will also generate resources when receiving the packets In (Jeon 2006) four
different terms of jamming attacks that an intruder could use to interrupt the
wireless network activity Tampering is yet another physical layer assault
Table 11 Physical layer hazards and measures in UAV wireless
communication network
(Kumar et al 2014)
Hazard Security measures
Jamming Channel blacklisting and hopping
Interference Channel hopping and blacklisting
Tampering Security and key modification
Sybil Physical security of the system
Table 11 describes physical layer hazards and their security measures in WSN
which tampering and jamming are considered as the main attack in the physical
layer in WSN
141 Principles of security
The security requirement of UAV communication network is as follows (Kumar et
al 2014)
Confidentiality Ensure that only the approved sensor nodes could get the contents
of the texts
bull Authentication Ensure that the data is introduced from the sound source
bull Integrity Ensure that every received text has not been modified to be sent
by unauthorized users
14
bull Freshness Make confirm that no old information has been reiterated
bull Availability services are feasible at any time through WSN or by a single
node
The standard attacks of the physical layer are as follows (Sastry et al
2013)
bull Jamming The transmission of the radio signal can interfere only with radio
frequencies used through WSN which is known as jamming As the
capacity grows it may influence more significant portions of the network
by transmitting other radio signals The opponent will use a few nodes to
occupy the entire channel This state is called physical layer jamming which
results in a denial of service In this scenario the opponent will not be
permitted to have any knowledge but will be capable of preventing
communication to any nodes
bull Tampering Often the nodes tampered through an opponent This mode is
called tempering Here the attackers can destroy exchange and
electronically confront nodes to obtain information from counter measures
towards jamming that have been planned as spread as well as frequency
hopping
bull A security mechanism is used in WSN to track avoid and recover from
security attacks A wide range of security schemes can be devised to counter
malicious threats which can be classified as high and low levels
bull Secrecy and Authentication Most network sensor applications need
protection from eavesdropping packet alteration and injection Early
networks are used for connection layer cryptography as this approach offers
the easiest deployment of network cryptographic solutions
bull Privacy Like all other conventional networks the radio networks have also
brought secret issues to allow Initially sensor networks are implemented
for legitimate purposes and can eventually be used unexpectedly
Knowledge of active sensor nodes as well as the acquisition of data is
exceptionally crucial
15
bull Critical launch and trust setup The primary prerequisite for setting up a
network is the development of keys (cryptography) Sensor devices
typically have minimal computing capacity and public cryptographic
primitives are too difficult to adopt Critical establishment and strategies
need to be scaled to network with thousands of nodes
bull Secure routing Routing as well as data forwarding is a problem that
confronts to facilitate communication in networks Regrettably the latest
protocols encounter a variety of security flaws
bull Robustness of communication Does An opponent challenges to interrupt
the operation of the network
Figure 14 Security problems in the UAV
Figure 14 illustrated the security difficulties in a UAV The physical layer security
in the UAV wireless networks was examined The UAV had affected by both active
eavesdropper and passive eavesdropper This paper proposed the trajectory design
and cooperative UAV for constraining the eavesdropper NOMA MIMO mm-
Wave frequency band in UAV would cause better spectral efficiency and security
(Xiaofang Sun et al 2019)
UAV implementation of the 5G communication was considered advantageous The
UAV was assumed as the novel wireless network technique for the territory users
and their base stations The UAV had resulted in high altitude So the UAV had
16
considered a superior line of sight At the same time the possibility of security
problems was raised in a UAV The secrecy in the existence of eavesdropper the
jammer in the ground was performed using the UAV UAV aided territory security
was proposed The UAV was involved in inspecting the eavesdropper and hazard
jammers on the base stations territory UAV had targeted the global position system
spoofing for assisting the authentic users and performed the role of an artificial
eavesdropper for excluding the eavesdropper and jammers in the ground (H-M
Wang et al 2019)
15 Non-Orthogonal Multiple Access (NOMA) System Secured
Communication
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
151 Comparison of NOMA Vs OMA
Comparison of the NOMA and OMA can be discussed as follows
17
1511 Spectral throughput and efficiency
In OMA a resource is allotted to the distinct user whether it is good or bad in a
channel scenario like OFDMA Thus the whole process moves from less
throughput and performance
While the same frequency is allotted to the multiple-use at the same time with good
or bad channel operation in NOMA here the weak user gets the allocated for the
resources which the strong user can also use it And the interference can be reduced
by the SIC process on the receptor side of the user Consequently the probability
with the increased spectral efficiency as well the high throughput will be
maximized
1512 User fairness and higher lately
A user of fair channel complaints has higher precedence to be served in OMA In
contrast a user with a poor channel complaint is to remain activity which causes
the issue of user fairness and higher latency Yet OMA cannot assist colossal
connectivity Whereas NOMA helps multiple users with various channel
procedures and offers increased fairness massive connectivity and lower latency
1513 Compatibility
NOMA has compatibility with the current and upcoming scenario meanwhile no
need for necessary changes to the previous methods As an instance NOMA has
been bought up in the 3G Partnership Project LTE Advanced (3GPP LTE) Though
NOMA contains many characteristics that can assist the upcoming generations and
it has some restrictions that can be explored with its full benefits Those restrictions
are as follows
bull Each user has to decrypt the signals of other users until decrypted their
signal the complexity of the receiver would be strengthened in NOMA as
opposed to OMA which creates a long pause
bull Also data on channel quality for all users should be returned to the BS but
this results in substantial CSI input overhead Furthermore if any issues
arise to any consumer during the SIC process the likelihood of consecutive
decrypting errors will be improved
18
Figure 15 Comparative analysis of NOMA vrsquos OMA
As an outcome the number of users is reduced to ignore the spread of such
debugging Another aim of restricting the number of users is that there must be
substantial variations in channel revenues between users with different channel
grievances to provide network reliability
16 Problem Identification
The NOMA-based architectures main feature is to configure trusted and untrusted
users when more than one eavesdropper is present in the dense setting of todayrsquos
and future sophisticated wireless communication networks This research aims to
examine the security efficiency suggested for mission-critical applications in the
NOMA-based UAV communication network The proposed system underpins two
user NOMA frameworks The possibility of paring both users was explored with
PHY performance measures in mind Outage probability (OP) and Secrecy Outage
Probability (SOP) Dynamic Optimization Method Programming (DP) and Partially
Observable Markov Decision Process (POMDP) optimization have also been
analyzed to explore the feasibility of achieving an outage-optimal output for the
pair under the heavy users secrecy outage restriction The optimized theoretical
findings are applied to the multiuser scenario The identifications were tested
through a computer model in which POMDP has shown substantial progress over
the dynamic optimization method to program
19
17 Motivation
Unmanned aerial vehicle (UAV) wireless communications have experienced an
upsurge of interest in both military and civilian applications due to its high
mobility low cost on-demand deployment and inherent line-of-sight air-to-ground
channels However these benefits also make UAV wireless communication
systems vulnerable to malicious eavesdropping attacks
Despite the promising gains brought by UAVs the open nature of air-to-ground
wireless channels makes secure information transfer a challenging issue
specifically on the one hand information signals transmitted over wireless LoS
channels are likely to be intercepted by some undesired receivers which lead to a
risk of information leakage On the other hand wireless UAV transceivers are
vulnerable to malicious jamming attacks Hence security plays an extremely
important role in UAV wireless communications Unfortunately traditional
encryption techniques require high computational complexity leading to a large
amount of energy consumption which may not be suitable for UAV systems As an
alternative physical layer security is computationally efficient and effective in
safeguarding wireless communication networks via exploiting the inherent
randomness of wireless channels As a result various physical layer techniques
have been proposed in the literature for guaranteeing communication security
NOMA is viewed as a promising technique to provide superior spectral efficiency
by multiplexing information signals at different power levels [13] Hence it is
expected that NOMA can bring additional rate and robustness to enhance the
achievable rate in UAV physical layer security communications Consider a
scenario where a UAV acts as a relay to facilitate data delivery to two receivers
with different security clearance levels within a maximum cruising duration T The
receiver with a lower security clearance level and a higher potential with an
eavesdropper Since it has a strong motivation in intercepting signals intended for
a receiver with a higher security clearance Then when the eavesdropper suffers
from a bad channel condition NOMA is adopted to forward both confidential and
public information simultaneously Otherwise UAV only broadcasts the public
information for security issues The mode selection between NOMA and unicast is
20
chosen based on the results of the proposed resource allocation optimization In
particular for maximizing the spectral efficiency one needs to jointly optimize the
transmission scheme resource allocation and UAVrsquos trajectory However the
coupled optimization variables generally result in non-convex optimization
problems which are difficult to solve optimally As an alternative an iterative
suboptimal algorithm based on successive convex approximation can be employed
to facilitate a computationally efficient joint design We have discussed that the
NOMA scheme always outperforms OMA in all the considered scenarios which
demonstrates the spectral efficiency advantage brought by NOMA in striking a
balance between public data rate and confidential data rate
The main motive of this research is to enhance the inherently insecure PHY layer
of the NOMA-based UAV communication network NOMA-UAV communication
network requires feasible paring between trusted amp untrusted users (attacker) for
cooperative communication mainly in real-time field applications The power
allocation factor need to be optimized as per the trustworthiness of the associated
users (reliable user) and keeping the outage probability minimum for secured and
cooperative communications The pair Outage Probability and the SOP have been
optimized jointly for feasible pairing between BS amp the associated Users
18 Aim and Objective of the Research
The proposed works main objective is to examine the design of a NOMA-based
UAV communication network for enhanced Physical Layer security (PLS)
features Remarkably it is anticipated infrastructures and resources to connect
numerous devices and provide various services Researchers these days
concentrating on ways to design a heterogeneous framework like deployed small
cells air and ground-based deploy multifarious communication methods in 5G
such as millimeter-wave (mm-Wave) device-to-device (D2D) massive multiple-
input multiple-output (MIMO) Cognitive Radio (CR) and so on for improving
spectrum and energy efficiency
As a critical need especially for emergency applications the adoption of NOMA
transmission of UAV communication needs to be improved PLS A new optimal
resource allocation algorithm for some more robust and stable communication in
21
single and multiuser scenarios has been suggested here The PLS in dense
heterogeneous sensor networks has improved by the feasible pairing of trusted and
untrusted users (K Cao 2019 T Zhao 2018) In the instance of untrusted users
dynamic programming and POMDP are subjected to the channel conditions
details optimizing OP and SOP as a restricted parameter accompanied by resource
allocation (Davis 2018 L Hou 2018)
The main aim of the proposed research work areas
bull To analyze the underlying NOMA UAV communication framework with
enhanced Physical Layer security (PLS) implications for particular quest
applications
bull To examine the potential pairing of trusted and untrusted users in the
NOMA-based UAV contact network with two users and multiuser scenarios
for certain channel conditions called Channel State Information (CSI)
bull To maximize resource allocation among trusted and untrusted users by
pairing OP and Secret Outage Probability (SOP) as performance measures
with the POMDP optimization method
bull To evaluate POMDP and dynamic programming resource allocation with
two users and multiple users for both protected NOMA-based UAV
communication network scenarios
19 Thesis Organization
Chapter 1 Provides the introduction and basic concept of the proposed work with
the problem identification motivation and aim and objective of the proposed work
Here we described LTE 4G and its advanced techniques than about the NOMA and
its basic scheme UAV concepts represent their types and basic working strategy
Chapter 2 Provides a survey of the existing technologies which is related to the
proposed work The NOMA transmission schemes Merits and De-merits related
to security UAV assisted communication in heterogeneous sensor networks UAV
networks of 5G and beyond communications has been explained then about UAV-
NOMA PHY secured communication techniques as well
22
Chapter 3 Describes the proposed work of improvement of physical layer
insecurity of the NOMA The overflow and its performance measures with
simulated output have been defined in this chapter
Chapter 4 Describes Migrations proposed work from 4G LTE to advanced PHY
techniques for UAV communication The overflow and its performance measures
with simulated output have been explained in this chapter Concludes and explains
the proposed work with its outcome and the future scope of the proposed work
23
CHAPTER 2
LITERATURE REVIEW
21 Integration of UAV Networks for 5G and B5G communication
5G and B5G had been anticipated to give a unique connection among universal
users The UAV had been emerged for its advantage of wireless network and
relaying high data rate The UAV in the 5G and B5G was introduced and 5G and
B5G were updated with the new concept of Space-Air-Ground Integrated Networks
(SAGIN) Three layers were established named physical network communication
link and evaluation Besides the usage among the dense population IoT was
applied in satellite communication In which the IoT had provided the uninterrupted
service with high data rate communication The scope for flying UAVs had been
created for enhancing the number of mobile users with IoT (Ali et al 2018)
5G and B5G had projected the UAV as the vital constituent One to multiple point
transmission can be possibly advance in 5G and B5G The structural design of the
upcoming UAV (multi-tier drones) was driven by the routine of different structures
like the maximum functioning altitude communication overlap coverage and
determination The UAVs practicability (multi-tier drones) among conventional
UAVs (single-tier drones) is scrutinized in that perspective By ascertaining the
circumstances UAV (multi-tier drones) could supplement the older terrestrial
networks with RF Initially UAV (multi-tier drones) and drone-aided wireless
networks were related to finding the tasks The modified UAV (multi-tier drones)
and the drone-administered wireless networks were analyzed The enactments of
UAV (multi-tier drones) were scrutinized in the contest of spectral efficiency in the
downlink networks Their effect had exhibited the detailed network parameters The
UAV distribution (multi-tier drones) was considered advantageous for the spectral
efficiency from the downlink transmission over traditional terrestrial wireless
networks (Sekander et al 2018)
The growth of 5G and B5G wireless networks prominently hang on the
incorporation of the terrestrial and aerial systems in innovative heterogeneous
network architecture They had advanced a creative and tangible multiple UAV
24
made up of cluster UAV ndash base stations and Poisson point process with UAV and
mm-Wave frequency band Ground user equipment and UAV had exhibited as the
Poisson cluster process and then spread around the public cluster in the distinctive
cluster In particular the scrutiny was accompanied by the accumulation of extra
tiers Extra tiers were made up of multi-cluster UAV base stations and single ground
user base stations in the characteristic cluster Four-tier network systems were
designed correspondingly from the subdivision of the above-said base stations
Two-tier and four-tier association patterns were built for discovering the
involvement of the cluster networks The coverage probability for the downlink and
network throughput was derived (Ji et al 2020) The numerous subordinate title
role of the multifaceted communication systems was performed by the UAVs The
UAV was acted as the air relay in the maintenance of ground networks The UAVs
were used in the countryside hilly zones whereas the communication was
inadequate The author anticipated resolving the viable communication difficulty in
5G and B5G vehicular ad-hoc The associate communication pattern established on
the smart UAVs was planned given the crisis condition of the car ad-hoc The smart
UAVs were supporting the vehicular ad-hoc strong communication in real
situations Above and beyond its actual characteristics of the vehicular ad-hoc were
needed to be endangered to avoid the prohibited features from attaining and
exhausting for law-breaking practices Innovative UAV with a secret authentication
key arrangement was recommended in the 5G and B5G vehicular ad-hoc Because
of supporting efficiency the vehicle network which guaranteed communication
confidentiality was not negotiated The suggested pattern was confirmed to be
unaffected by numerous outbreaks by exploiting the broadly applied natural or
random ROR scheme
Furthermore the projected scheme had well calibrated the communication
overhead from the performance estimation (J Zhang et al 2020) The UANs had
obtained a phenomenal role in the research area the emergent sector of aerial
robotics The parcel transport organization monitoring occurrence shooting
surveillance and tracing were the metropolises general operations utilizing the
UAV Various domains would use 5G and B5G to improve UAV networks UAV
ecological unit was advantageous in present 5G and B5G mobile communications
For UAVs intrinsic features they were concerned for flexible movement of three-
25
dimensional space independent actions and smart locations These devices were
provided with extensive scope in cellular networks The author proposed an in-
depth assessment of implementing cooperation between UAV and 5G and B5G In
which UAV had been assimilated as a novel user equipment of aerial in present
mobile communications The UAV had implemented the duty of flying users within
the network coverage named the cellular-connected UAVs in this amalgamation
The author showed a broad examination of the incorporation tasks with 5G and
B5G novelties Continued efforts in the prototyping and validation of mobile
communication UAVs were conducted using the ground trial The paper had
focused on the current growth in 3GPP The social-economic had not been taken
into account which was considered disadvantageous (Mishra amp Natalizio 2020)
The UAV was anticipated as the significant constituent in the 5G and B5G wireless
networks 5G enables the UAV to be used in broadcasting and end-to-end
communications using the small UAV They needed a devoted and endangered
aerial spectrum in the aircraft cargo by letting small UAVs run in space in
supervisory authority The security information was obtained from the link Control
and Non-Payload Communications (CNPC) The security information contained
the regulation of UAV and the line of sight of terrestrial The CNPC application in
the 5G and satellite communication was scrutinized in this paper Payload
communication like mm-Wave networks and UAV were analyzed in this paper The
direction-finding and reconnaissance difficulties were examined UAV
communication systems were scrutinized and the hardware challenges were
discussed (Hosseini et al 2019)
The potential gain from the UAV-assisted data gathering was found in
indiscriminate IoTs The characteristic propagation was represented by utilizing the
complicated channel method (contained small- and large-scale fading) IoTs were
updated in constrain of transmit power (in high) and total energy The multi-antenna
UAV was selected in the IoTs in sequence The virtual MIMO was created by the
communication between UAV and singe antenna IoT in every transmission (W
Feng et al 2018)
The UAV was applied in the aerial coverage surveillance agricultural prediction
constructional areas and power line supervising and blood donation The flight
26
period increment payload capability fast movement and speedy placements were
implied features in the UAV so that the UAV was exploited by the applications of
5G and B5G (Ullah et al 2020)
The UAV was considered a motivation for many emergent usages and reformed
social-economic welfares The wireless networks for the UAV and the base stations
were desired for the UAV function Mobile communications were considered
suitable for finding tracing and regulating the flying UAV The wireless
communications were selected for their features of broad coverage quality of
service and secrecy The wireless communication in the UAV improved
productivity besides the line of sight (G Yang et al 2018)
22 UAV-NOMA in Physical Layer Security enhancement
The NOMA has been applied in the fifth generation (5G) technology The Multicast
Cognitive Radio (MCR) network is implemented using the NOMA and coined as
MCR- MOMA The transmission side is also included with the superimposition
code The decoding was applied at the receiving end So an unknown user is
deduced in their methodology (Meng et al 2020)
The physical layer security for the cooperative NOMA was examined Amplify
and forward decode and forward were taken into consideration for achieving
secure transmission (Chen et al 2018)
The physical layer security of the NOMA was analyzed in the broader network with
varying locality The single and multi-antenna were established in the following
cases The single antenna was taken for an end-to-end connection in a secured
manner And the multi-antenna was used for the connection of base station and
random user Finally achieved security for the multi-antenna on the transmission
side The security of the single antenna was attained by introducing the excluding
area for eliminating eavesdroppers The individual expression of security outage
probability for both single antenna and multi-antenna were derived (Yuanwei Liu
et al 2017)
The secure transmission of NOMA in large-scale applications was investigated
Stochastic Geometry was utilized for placing the eavesdropper and user nodes The
equation for secrecy outage probability was derived and expressed for evaluating
27
secure transmission Security can be improved by expanding the protected zone
(Qin et al 2016)
The power domain NOMA had the disadvantage of decoding data by other
unauthentic users of the same source For reducing unauthentic users the base
station should treat the unauthentic users with different cleaning methods The
secrecy outage probability was investigated for authentic users and unauthentic
users Both users were combined as a pair to the non-uniform distribution of original
and unauthentic users The pair outage probability of genuine users from the secrecy
outage probability restrained NOMA authentic users The derivation for pair outage
probability and the secrecy probability were expressed for calibration The
combined system had been the better security (ElHalawany amp Wu 2018)
The physical layer security was considered problematic in the wireless networks
mainly for keeping the authentic userrsquos data The UAV was acted as the base
station UAV based base station had sent the extensive data to the original users
NOMA with the multi-antenna with mm-Wave frequency band transmission had
enhanced the spectral efficiency The physical layer security was attained by
announcing the space around user locality as the eavesdroppers protected zone
Covering the entire eavesdropper area was considered a resource-consuming way
The shape optimization for the protected location in each UAV base stations
altitudes was introduced The derivations for the secrecy sum rate and the secrecy
outage probability were expressed (Rupasinghe et al 2018)
The vehicular communication system had used cooperative NOMA The secrecy
outage probability was considered in vehicular communication The relay can be
used in both modes (half-duplex and full-duplex) in vehicular communication The
closed derivation for the secrecy outage probability was expressed The security of
the full-duplex NOMA resulted better than that of the half-duplex NOMA The
limitations are that the velocity of the vehicles was not considered Figure 21 is
illustrated the conceptual model of the vehicular communication NOMA system
(Xie et al 2019)
28
Figure 21 Vehicular communication NOMA system
The physical layer security of the uplink NOMA of the large-scale devices was
examined The connection networks had investigated with the approach called
stochastic geometry The new derivation was expressed for the coverage
probability The protected zone restrains eavesdroppers to the authentic users
Efficiency secrecy throughput was examined wiretap channels and the many
original users Constant transmission and variable transmission were collectively
inspected The signal to noise and the movement to interference ratio were derived
drastically (Gomez et al 2017)
The wireless system was executed using Space-Time Block Coding (STBC)
approach in the NOMA of mm-Wave MIMO The technique focused on haphazard
users So the pairing method was introduced mainly for Random Near-Random Far
(RNRF) Here the latent period could be minimized and the RNRF has also been
deduced for the overhead issue The result revealed the systems efficiency with a
proper implementation (Ghavidel et al 2020)
The recent arbitrary beam forming method was proposed in the multiple access
NOMA The pairing had decided to the user places So the evaluation was focused
on the system overhead The result revealed that the proposed work outperformed
29
the existing methods (Aghdam et al 2020) NOMA enhances the reliability of
multi-users transmission The sum rate could be reduced for improving Quality of
Service (QoS) power transmission and signal outage probability The
eavesdropper easily accessed the multi-access systems that cause physical security
during transmission (Z Li et al 2020)
The NOMA had provided spectral efficiency speed transmission of data multiple
networking and less latent period The NOMA utilizes the power domains for
various access Cognitive Radio Networks (CRN) is used to screen illegitimate
users The legitimate users were only permitted in the CRN by the Primary User
Networks (PUN) QoS The cooperative NOMA here implemented with the PUN
and the system performance is enhanced The spectral efficiency can be improved
by the secured transmission The cooperative NOMA was additionally developed
in the CRN with the PLS A new method of cooperative NOMA in the CRN was
examined The PUN technique attains a secure transmission Multiple antennae
were used in this study for reliability and the eavesdropperndashexclusion zone method
is used for better security (B Li et al 2018)
The downlink NOMA for moderate CSI was examined The challenge of the power
domain was rectified by allocating power NOMA The power in NOMA and that
of the OMA was analyzed which resulted in a significantly reduced NOMA (Cui
et al 2016)
Here the users were multiplexed by the power domain So the method was coined
as power domain NOMA The demand arising from the B5G (Beyond 5
Generation) had reached using power domain NOMA Machine learning in the
NOMA was described (Maraqa et al 2020)
The uplink NOMA with the PLS was proposed The uplink NOMA contained a
single base station and multi-users a couple of users combined for NOMA The
known jammer emitted the pseudo-noise to divert the eavesdroppers The study had
suggested the two jammers in the uplink NOMA for secure transmission (N Zhao
et al 2020)
The Intelligent Reflecting Surface (IRS) is designed using downlink NOMA The
multi-access had used the space direction of the beams of closure users The IRS
30
had performed the multi-access for every spatial order by the cell edge users of the
orthogonal beams (Ding amp Poor 2020)
The multi-input single-output NOMA has introduced the technique called Secrecy
Beam Forming (SBF) SBF had utilized the artificial noise for NOMA security
aided users in which the eavesdropperrsquos channels deteriorated The SBFs secure
transmission can be achieved in which high successive interference cancellation is
gained (L Lv et al 2018)
The superposition coding was performed in the transmission pat The successive
interference cancellation was conducted in the receiving position These two
techniques were combined in the novel 5G aided NOMA The basic concepts of
uplink and downlink NOMA were mentioned The dominant condition was
performed in the two user clusters of NOMA The prevailing state had issued the
confirmed spectral efficiency gain in NOMA (Tabassum et al 2016)
The relay scheme in IoT was examined for the secrecy of NOMA This was coined
as relay selection NOMA The base station had transmitted the secret messages to
the two NOMA-aided sensors and eavesdroppers IoT had treated the sensors and
eavesdroppers with different power allocations The expression for certain outage
probability and the strictly positive secure capacity was derived Increasing the
number of the relay would enhance the security in the NOMA-aided IoT The
outage probability for NOMA and OMA were compared The NOMA resulted in
better outage probability in Decode and forward mode (Do et al 2019)
31
Figure 22 RS-NOMA against an external eavesdropper
The NOMA-aided IoT was utilized to fight against the external eavesdropper as
Figure 22 The secured NOMA was proposed The base station sent secret
messages to several authentic destinationsmdashseveral eavesdroppers and unauthentic
users
Nakagami-m fading model was carried out using the multiple antennae in the
channel The security was attained using the max-min transmit antenna selection
scheme Both authentic and unauthentic eavesdroppers were analyzed The closed
derivation for the cumulative distribution of the original user was expressed first
That was compared with the unauthentic user The derivation for the secrecy outage
probability was obtained to identify the level of secrecy performance (Lei et al
2018)
Reconfigurable intelligent surface (RIS) aided NOMA was established for the
secrecy performance The main disadvantage of this model was the chance of using
RIS by the eavesdropper The secret outage probability was derived in this paper
The RIS improved the secrecy of the traditional NOMA The eavesdroppers were
limited from receiving the RIS signal by enhancing the number of intelligent
elements in the RIS A high signal-to-noise ratio was obtained from this experiment
(Liang Yang amp Yuan 2020)
32
The cooperative relaying NOMA was proposed for improving private transmission
in wireless networks Full duplex mode transmitted the jamming signals That
received the required communication at first Secondly the jamming signal
emission was sent by the base station The power allocation for the jamming signal
and information signal was decided on the eavesdropper channel state information
The eavesdropper was jammed by the signal from the first phase with maximum
power Second the derivation of the secrecy outage probability was expressed by
static eavesdropper CSI (Y Cao et al 2020)
The NOMA achieved spectral efficiency and secrecy The security of the multi-
NOMA users was obtained by the successive interference cancellation (SIC)
decoding in the receiving node The conservation of the untrusted NOMA was
concentrated in this study The security can be confirmed by the properly secured
decode processing and allocating power The decoding scheme was implemented
for aiding NOMA users The decoding was performed for enhancing the sum-rate
(Thapar et al 2020) The cognitive radio network in NOMA with the external
eavesdropper was proposed (Mehr et al 2020)
The cooperative NOMA was used in the field of energy harvesting communication
The novel relaying technique was introduced for achieving secrecy The secrecy
outage probability was derived and the derivation was expressed for the three
conditions The first condition was the derivation of CSI with a passive
eavesdropper The second condition was the derivation of CSI with the unauthentic
eavesdropper The third condition was the derivation obtained from the multi-relay
nodes The increased SNR resulted in high security The increase in the number of
users deduced security This was considered a disadvantage (Salem et al 2020)
Satellite communication covered more range of broadcasting So the security
challenge was considered a big difficulty in satellite communication Downlink
NOMA was assessed with an eavesdropper for the examination of secrecy The
paper concentrated on the physical layer security of downlink satellites Here two
methods were proposed The frequency-domain NOMA was considered for gaining
spectral efficiency The multiple user interferences were obtained in the process of
overlapping Introducing a suitable technique can be performed the security for the
number of users The secrecy rate was analyzed for all authentic users (and the
33
eavesdropper) and expressed in the derivation The safety was improved using the
spectral overlap method (Yin et al 2019)
The NOMA was considered as the emerging scheme in the upcoming wireless
networks The secrecy sum rate for the downlink NOMA (with MIMO multiple
inputs multiple outputs) was examined Downlink NOMA had the base station
number of users and the eavesdropper In the limitation of transmit power and
optimal successive interference cancellation the security was expected to enhance
Downlink MIMO NOMA was considered advantageous because of its secrecy
performance and the practical usage of bandwidth The mutual information rate and
the mean square error were causing the secrecy rate optimization to the problem of
biconvex This was rectified through the alternative optimization method and the
second-order cone programming was solved (Tian et al 2017)
Table 21 Comparative analysis
The comparative analysis for the physical layer security was examined in existing
studies
SR
No
Details of Author wise Contribution to NOMA Technology
1 Author (YFeng Yang amp Yan 2017) Secrecy performance in NOMA was
conducted with the help of artificial noise in the full-duplex mode of relaying
Methodology The optimization of the power was calibrated for the source
information and the noise signal The closed derivation for the secrecy outage
probability was expressed
Usage and limitations The physical security was increased
34
2 Author (He Liu Yang amp Lau 2017) NOMA was developed in the constrain
of security
Methodology The secret message had been sent to some users and also to the
eavesdropper The Novel decoding process was conducted for excluding the
unauthentic users The iterative algorithm was used for power optimization
Usage and limitations Transmit power was reduced The quality of service
was availed
3 Author (D Wang et al 2020) The secrecy was performed in the NOMA
The security was developed against the eavesdropper outside
Methodology The channel state information was analyzed for secrecy The
quantization of CSI had performed for secrecy The derivation for the secrecy
and transmission outage probabilities were obtained
Usage and limitations The secrecy rate was enhanced
4 Author (L Lv et al 2020) The physical security of the NOMA was
improved by adding artificial noise jammer and inter-user interference The
mode of full-duplex in the updated version was used in the NOMA
Methodology The eavesdropper can be trapped the superimposed signal from
the source So the secrecy was affected
Usage and limitations The spectrum usage is effective in the NOMA
transmission scheme Numerous connections can be performed in the NOMA
NOMA is considered to be the most advantageous for the upcoming
generation communications The superimposition technique was followed
4 Author (Yue et al 2020) Secrecy performance of the NOMA was developed
with a unique framework
Methodology The eavesdroppers inside the zone and outside the coverage
zone were examined properly in this paper The outage probability for codendash
power domain NOMA was derived
Usage and limitations Safety was acquired for both internal eavesdropper
and external eavesdropper in this scheme
35
5 Author (Guezouli et al 2020) The heterogeneous sensor network of cellular
communication was taken into account
Methodology Unmanned aerial vehicles are utilized the heterogeneous
sensor network of cellular communication
Usage and limitations Extended the life span of the network system The
cost of the hardware components is drastically low The random and the
repeats in the speedy movement The latency is maximized The coverage
period is maximum
6 Author (Yao amp Xu 2019) The security in transmitting a large amount of
information in the wireless network systems are analyzed with unmanned
aerial vehicle UAV
Methodology The numbers of UAVs are arranged in the space The base
station sent the information to the UAV in the space The authentic receivers
have obtained the secured information from the UAV The HPPP
homogeneous Poisson point process is used for distributing the authentic
receiver and eavesdropper in the line of sight
Usage and limitations The increase in the number of safety zone causing the
secured transmission
7 Author (Saacutenchez et al 2020) Physical security can be achieved by the
method of a unique encryption scheme
Methodology The physical layer security of the following schemes is
discussed in this paper mm-wave NOMA massive multi-input multi-output
heterogeneous sensor networks full-duplex mode
Usage and limitations The physical layer security was analyzed for the 5G
supporting technologies Good reliability achieved The less latent obtained
Machine-type communications can be enabled
36
8 Author (Hou et al 2018) The multi-antennas were used in NOMA with
UAV The stochastic geometric approach was examined
Methodology The multi-input multi-output kind of NOMA was utilized In
common the stochastic geometric approach was used for drastically moving
NOMA
Usage and limitations The maximum signal-to-noise ratio was obtained in
this scheme Power optimization was achieved The path loss is less Good
spectral efficiency was obtained
9 Author (Miao et al 2020) The broadcast type of communication was
performed The less weighed three-dimensional space for 5G communication
was analyzed
Methodology Both the performances of multicast and broadcast were
enabled UAV-assisted 5G communication systems are emerging in the
upcoming wireless networks
Usage and limitations Better flexibility in the network Continuous mobility
One lined line of sight
10 Author (Majhi amp Mitra 2020) The secure communication in cognitive radio
by NOMA was propounded
Methodology The antenna strategy of giving minimum outage probability
was concluded from this study
Usage and limitations The limitation is that more spectral efficiency causes
security issues
11 Author (X Zhao amp Sun 2020) Secure communication of the physical layer
in Visible light NOMA Communication was proposed
Methodology Energy optimization in security constrain was propounded for
achieving overall performance
Usage and limitations It is difficult to find optimal results because energy
optimization is the nonconvex issue
37
12 Author (Tuan amp Hong 2020) Secure communication in simultaneous
wireless information and power transfer NOMA was remitted
Methodology Eavesdropper is used for security purposes between the user
and base station using energy relays Known jammer is used for secure
transmission For energy efficiency storing and transferring were propounded
Usage and limitations Jamming requires extra power allocation
13 Author (Vaezi et al 2019) NOMA for 5G in mmWave MIMO cooperative
and cognitive were analyzed in this study
Methodology SWIFT NOMA is useful for weak receivers
MIMO using more antenna
Usage and limitations multi-antenna utilization cause high power
consumption
14 Author (Vaezi et al 2019) Mobile edge computing NOMA was proposed to
optimize power
Methodology Minimum latency and less power consumption
Usage and limitations Transfer power allocation must be calibrated
15 Author (Faraji-Biregani amp Fotohi 2020) Security in UAV communication
was proposed by introducing mobile agents
Methodology Malicious user of UAV was identified
Usage and limitations Three-phase power is essential
16 Author (G Zhang et al 2019) Secure communication in 5G UAV was
propounded by joint trajectory carrying out in physical layer
Methodology Power optimization was proposed for security
Usage and limitations Security in the physical layer was achieved by
optimization of trajectory
17 Author (Fotohi et al 2020) Agent-based self-protection was propounded in
UAN for secure communication
Methodology This method imitates the immune system of human beings
Less cost
Usage and limitations Energy is not optimized properly This approach
needs to consider other malicious attackers
38
18 Author (Shang Liu Ma amp Fan 2019) Vehicle to everything approach was
propounded for security in a UAV
Methodology Security of vehicle to the vehicle was proposed by considering
eavesdroppers active and passive attacks
Usage and limitations High price
19 Author (Kantor et al 2017) The flight path was calibrated in a UAV
Methodology Security performance was achieved by encryption as well as
anonymization
Usage and limitations High in cost and hardware structure occupies more
place
23 Research Methodology
The NOMA-based cellular architecture for UAV communication has been
considered here as reference network architecture Rayleigh fading has been
assumed as a channel characteristic The performance parameters for PHY layer
security are (1) Pair Outage probability (Pair OP) between two users trusted near
user designated as U1 and untrusted far user designated as U2) and (02) Secrecy
Outage Probability (SOP) of trusted near user designated as U1 The aim is to
achieve optimal Pair OP for the given constrained SOP of User U1 so that network
resources can be efficiently allocated to both users without compromising the
secrecy of trusted User U1
The mathematical analysis from reference literature (ElHalawany et al 2018) has
verified and supported the joint optimization of the Pair OP and SOP for the given
power allocation factor in NOMA This research work is extended as providing
more efficient resource allocation using the POMDP algorithm in a given scenario
First the varying distance of untrusted user U2 from BS as a critical selection
parameter that affects Pair OP amp SOP of user U1 and U2 both has been simulated
and the feasible and infeasible pairing of both users have been analyzed The
optimal power allocation factor for feasible pairing as the constrained problem is
optimized by opting for POMDP as a resource allocation algorithm wherein the
SOP of user U1 is strictly maintained for given CSI POMDP provides optimum
39
power allocation factor for trusted and untrusted users pairing as shown in the
proposed flow of POMDP algorithm is used to model a variety of real-world
sequential decision-making problems After the BS has been set up the distance
between the BS and the user is calculated and if space is less than 200m it is
defined as a trusted user While if the range is more than 200m it is described as
untrusted users In the case of trusted users the channel state information (CSI) is
provided to the proposed algorithm POMDP for reliable and efficient resource
allocation
24 Summary
UAVs play a central role in providing network service recovery in a disaster-
stricken region enhancing public safety networks or handling other emergencies
when Ultra-Reliable Low-Latency Communication is required In particular UAV-
assisted communication can be regarded as an important complement to the 5G
cellular networks Surveyed literature related to UAV communications published
over the past several years emphasized the cybersecurity and channel modeling for
UAV communications etc Security is one of the critical issues in communications
Modern communication networks are based on the layered architecture from the
physical layer up to the application layer A great deal of effort has been made to
develop the cryptographic protocols above the physical layer However the
physical layer is not as robust as that in wired communications The physical layer
in wireless communication is more complex than the counterpart in other
communication paradigms The concerns come from not only the noises but also
many types of fading Recently there has been an influential interest in studying
the security issues in the physical layer Security is highlighted as another
challenge and the implementation of physical layer security techniques is seen as
a difficult task PHY security in NOMA systems under the presence of external
eavesdroppers or untrusted relay nodes Upcoming 5G networks for unpredicted or
crisis (disaster management) the placement of terrestrial substructures is
economically infeasible and challenging due to high operational expenditure as well
as sophisticated and volatile environments
To address such novel issues intelligent heterogeneous architecture by leverage
UAV has been well-thought-out to be a promising novel model For advancing the
40
performance of the UAV 5G communication system physical layer techniques are
of many effects as they have impacted the applications of UAVs Security of
NOMA-based UAV communication network has been scrutinized for optimization
as physical layer security
41
CHAPTER-3
SYSTEM MODEL FOR NOMA-UAV
COMMUNICATION
31 NOMA-UAV System Secured Communication for 5G
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
311 The basic scheme of NOMA
The NOMA system allowed several users to be served simultaneously by the
transmitter To transfer a linear combination of different signals towards the
recipient the system of proportional representation superposition coding (SC) The
transformed signal is provided through
σ ඥ119875119896 119878119896119870119896 =1 -------------------------------------- (1)
Where 119927119948 represents the transmit power assigned toward user k th
119930119948 indicates the normalized message used for user k th
42
The instantaneous total converses power is σ 119927119948119922119948=1 The received signal at user kth
and the eavesdropper are offered through
119910119896 = ℎ119896 σ ඥ119875119896 119878119896119870119896=1 + 119899119896 -------------------------- (2)
119910119890 = ℎ119890 σ ඥ119875119896 119878119896119870119896=1 + 119899119890 -------------------------- (3)
Where 119951119948 and 119951119942 indicated the zero-mean Additive White Gaussian Noise
(AWGN) at user k th with variance 1205901198962 and the zero mean AWGN at eavesdropper
with variance 1206481199422 respectively We assume that the noise variances at all the users
are identical
ie 12059012 = ⋯ = 120590119896
2 = 1205901198902
As per NOMAs process the SIC is followed by all users to decrypt the message to
the same decoding order Notice that it is not known what the optimal decoding
order is for the NOMA method that corresponds to secrecy
Therefore the mth message to be encoded to the user might not be the mth message
to the user As such we also have to add the π variable For example if 120587(1) =
3 then the first message to be decoded for the SIC is the message for the user 120645(119947)
forall j lt k before decoding its letter to remove the inter-user interference successively
Then the user 120645(119948) denotes its message while treating the news for all the user
120645(119946)foralli gt k as the interferences The received Signal-to-interference-plus ndashnoise
ratio (SINRs) at user 120587(119896) k lt K and user 120587(119870) to decode their messages are
respectively given by
119878119868119873119877120587119896=
120574120587(119896)119875120587(119896)
1+120574120587(119896) σ 119875120587(119894)119896119894=119896+1
119896 lt 119870 --------------------(4)
119878119868119873119877120587119870= 120574120587(119870)119875120587(119870) --------------------------------------(5)
Were 120574120587(119896) =หℎ120587(119896)ห
2
1205901199062
൘
43
Also the acknowledged SINR at user 120587(119898) to decrypt the message 120633120645(119948) 119896 lt
119898 le 119870 is given by
119878119868119873119877120587119896=
120574120587(119898)119875120587(119896)
1+120574120587(119898) σ 119875120587(119894)119896119894=119896+1
kltmle 119870 --------------(6)
Similarly the acknowledged SINRs by the eavesdropper of the message 120575119896 119896 lt
119870 and the message 120575119896 are respectively given by
119878119868119873119877120587macr
119896=
120574119890119875120587(119896)
1+120574119890 σ 119875120587(119894)119896119894=119896+1
klt119870 ----------------- ------(7)
119878119868119873119877120587macr
119896=
ȁℎ119890ȁ2119875120587(119896)
1205901198902 = 120574119890119875120587(119896) klt119870 ---------------------(8)
Where 120574119890=ȁℎ119890ȁ2
1205901198902൘
Notice that here expressions for the obtained SINRs at eavesdropper overestimate
the skill of eavesdropper Here a worst-case inference from the viewpoint of
legitimate users is made That is the messages have already been decrypted by the
eavesdropper for all users π (j) forall j lt k before attempting to decrypt the message
for the user π (k)
The presumption also assumes that the decrypting order and power distribution are
understood by the eavesdropper The eavesdropper may or may not recognize the
decoding order of the users and the allocation of power may or may not recognize
the messages for all users π (j) forall j lt k before attempting to decode messages for
users π (k) However since the eavesdropper has been unable to alert the authorized
customers of its capacity and the current CSI the approved user would be unable
to know the eavesdroppers details Therefore we have to pursue the worst-case
scenario for the permissible users point of view due to the liberality required by the
safety reports It highlights that the worst-case assumption in the study and design
of transmission schemes with secrecy requirements has been generally adopted
The proposed study has been evaluated using performance measures Here we
analyze NOMA with downlink and uplink networks suggested by SINR and Sum
44
Rate survey High SNR is then simulated to contrast the OMA and NOMA
processes
312 Downlink of NOMA
The Downlink of the NOMA network on the transmitter side is described in Figure
31 SIC method is supposed to be carried out successively on the receiver side of
each user until another signal is restored The coefficients of users are owed in an
inversely proportional manner based on their available bandwidth
Figure 31 Downlink NOMA network
A consumer with a poor available bandwidth has a transmission capacity of a
higher range than a consumer with strong available bandwidth As a consequence
the consumer with the higher power assumes the signals of other users to be noisy
and automatically restores the signal without conducting any SIC operation The
receiver of each consumer detects indications that are stronger than those of the
desired signal These impulses are then deducted from the power and this process
continues until the signal has been calculated Both users decrypt their signaling by
considering other users with lower correlations The signal is calculated as
45
119904 = σ 119886119894119875119904119883119894119871119894=1 -----------------------------------------------(1)
Where Xi is the user ithrsquos information through unit energy
Ps is the capacity of transmission at the BS
ti is the coefficient of power assigned for user i
Although without the need for lack of generality the channel profits are expected
to be graded as ȁℎ1ȁ2 le ȁℎ2ȁ2 le ⋯ ȁℎ119871ȁ2
Where 119945119923 is the coefficient of the channel of the user Lth
The received signal of the Lth user is calculated as
1199101 = ℎ119897119904 + 119899119897 = ℎ119897 σ ξ119886119894119875119904119883119894119871119894=1 + 119899119897 -----------------------------(2)
Where n1 is zero mean Complex Gaussian noise with a variance of 1206482SINR
analysis with the equation (2) the SNR of Lth user to identify the user 119895 le 1with
119895 ne 1
119878119868119873119877119871 = 1198861120574 ȁℎ1ȁ2120574ȁℎ1ȁ2൘ σ 119886119894 + 1119871
119894=119871+1 ------------------------(3)
Where 120632 = 1198751199041205902ൗ represents the SNR
Sum rate analysis After identifying the SINR of the downlink the sum rate will
also be done quickly
The NOMAs downlink data rate of Lth user can be calculated as
1198771119873119874119872119860minus119889 = 1198971199001198922(1 + 119878119868119873119877119871) --------------------(4)
313 Uplink of NOMA
The Uplink NOMA is depicted in Figure 32 where each user sends a signal to the
BS SIC iterations are supported to classify the signals of mobile users If both
channels are identical and BS sends the coefficients of power allocation to mobile
users the received signal can be interpreted as a synchronous uplink to the NOMA
46
119955 = σ ℎ119894ඥ119886119894119875119909119894119871119894=1 +n ----------------------------------(5)
Where hi is the coefficient of the channel for the ith user
119927119961119946 is the extreme transmission capacity supposed to be general to all users
N is zero-mean Gaussian noise with a variance of 1206482
Figure 32 Uplink NOMA
Analysis of SINR The BS decrypts the signals of the users as per the coefficients
of the users and the SINR for the Lth user can be defined as
119878119868119873119877119871 = 119886119897120574ȁℎ119897ȁ2120574 σ 119886119894ȁℎ119894ȁ2 + 1119897minus1
119894=1൘ ----------------------------(6)
Where 120574 = 1198751205902ൗ indicates SNR
Analysis of Sum rate The sum rate of uplink NOMA when 120632 minus infin can be
computed as
119877119904119906119898119873119874119872119860minus119906 asymp 1198971199001198922(120574 σ ȁℎ119897ȁ119871
119894=1 2 ------------------------ (7)
47
314 Comparison of NOMA and OMA
The attainable data rate of the Lth user of OMA intended for both uplink as well as
the downlink is estimated as
119877119904119906119898119874119872119860 = σ 120572 1198971199001198922120574(1 +
120573119897ȁℎ119897ȁ2
120572119897119871119894=1 ) --------------------------(8)
Just for convenience two users should evaluate the summation of uplink rates for
NOMA and OMA The use of both the uplink rate of NOMA and OMA at high
SNR can be calculated as---
119877119904119906119898119873119874119872119860 asymp 1198971199001198922(120574 ȁℎ1ȁ2 + 120574ȁℎ2ȁ2 ------------------------- (9)
equation (7) and (8) it is seen that 119877119904119906119898119874119872119860 le 119877119904119906119898
119873119874119872119860
Here we note 119929119956119958119950119926119924119912 le 119929119956119958119950
119925119926119924119912 shows that NOMA performed better than OMA in
terms of sum rate in both downlinks as well as uplink of two user networks
The sum rate will be calculated after the SNR as the formulation is shown In this
proposed work multiple users are propagated to the process of NOMA and here a
comparison of NOMA as well OMA has been defined The NOMA uplink and
downlink using the OFDMA method for the
32 PLS performance metrics in NOMA -UAV communication
This chapter mainly describes the proposed work to examine the availability of the
outage probability of the pair below an authorized user According to the decryption
of SIC availability and spectrum sharing the unauthorized user can function as an
eavesdropper and obtain an outage probability (OP) for all situations with the
Secrecy Outage Probability (SOP)
321 SOP and OP - two user and multi-user NOMA system
NOMA system has the capability for assigning multiple data over the transmission
signal through high-level coding (Shim amp An 2018) Thus it contains spectrum
efficiency when opposed to OMA But this has a limitation in security As an
48
instance if the eavesdropper is reached then it obtains multiple user data in the
interference of the NOMA signal Thus the security issues are more significant in
this system Here PLS is an available method to rectify the attack intended for
malicious users (Dai et al 2015)
Additionally data should be transmitted confidentially if the root and eavesdropper
networks can be evaluated and the recipient can decrypt the received text At the
same time the eavesdropper is not able to solve the text that has been interrupted
PLS is at the cutting edge of wireless communication security technology to prevent
eavesdropping attacks The SOP is described as the likelihood that the near users
attainable device confidentiality capability will fall under the predefined target
confidentiality rate as set out in (Shim et al 2017)
Through SOP we can calculate the level of protection of the device As an example
the low-secret OP system makes the system more stable in terms of security than
the high SOP system To boost the efficiency of the PLS CSI-based opportunistic
scheduling links to a scheduled destination in a particular time slot It has been
documented as an enticing scheduling scheme (Long Yang et al 2016) because the
various wireless channel has been exploited Opportunistic scheduling is also
considered to be one of the strategies used to increase the confidentiality efficiency
of the NOMA method
322 System Model
Suppose a multi-user NOMA system of downlink containing BS a selection of K
nearer users as N= 119873119894ȁ12 119870 and a range of M far users as F=
119865119895ȁ12 119872 and an eavesdropper E as displayed in Figure 33 More
specifically nearer users should make active use of the SIC methodology to
distinguish far user F Both the legitimate and illegitimate receivers are furnished
through a single antenna and operate in a half-duplex manner
49
Figure 33 Multi-two user architecture of NOMA system (Shim amp An 2018)
Here 119945119935119936 and ȁ119945119935119936ȁ2
Where X120598ሼ119878ሽ 119884120598119873 cup ሼ119864ሽ represent the channel coefficient and the corresponding
channel gain of the X-Y value
Taking into consideration that each wireless channel for Rayleigh block fading 119945119935119936
can be incorporated as an independently distributed random Gaussian variable with
zero mean and affirmative ℷ119935119936 Variance The outcome of channel gain ȁ119945119935119936ȁ2is an
exponential variable randomly through the Probability Density Function (PDF)
119891ȁℎ119883119884ȁ2(119911) = ቀ1
ℷ119883119884ൗ ቁ 119890119909119901 (minus 119911
ℷ119883119884ൗ )
if zge 0 119900119905ℎ119890119903119908119894119904119890119891ȁℎ119883119884ȁ2(119911) = 0 -----------------(1)
Especially the average channel profit can be represented as
ℷ119883119884= ൬119889119883119884
1198890൘ ൰
minus휀
ℒ ------------------(2)
When 120027 is the attenuation of the received signal 119941119935119936 signifies the distance among
X and Y 1199410 indicates the space and 120656 is the exponent of the path loss It is believed
that the source is entirely familiar with the CSI of both legitimate users and
eavesdroppers
50
323 Partially Observable Markov Decision Process-POMDP
Figure 34 Flow Diagram of the proposed system
The proposed overflow is shown in Figure 34 After the BS has been set up the
distance between the BS and the user is calculated and if space is less than 200m
it is defined as a trusted user While if the range is more than 200m it is described
as untrusted users In the event of untrusted users the channel state information is
accessible to the POMDP accompanied by the allocation of resources The study
was carried out after the machine operation Here a NOMA-oriented cellular setup
provided with a BS at the Centre and two users was described in Figure 35
51
Figure 35 Near and Far User
The adjacent user has a high level of security confirmation needed to protect the
layer since the low-security clearance user is situated at a distance away from the
BS P is specified as the highest level of transmitting power In this chapter it is
presumed that all DNS servers are furnished utilizing an individual antenna and all
channels are supposed to be individually static identical to the Rayleigh
dissemination concerning distribution
119862119873(0 120575119898
minus120572
212059601 2Τ
)
In which 120633119950 is the range between the BS and the nodes 119932119950 Here the path-loss
exponent and constant are defined as 120630 and 1206540 Furthermore BS is assumed to
have predicted the position of the user so that a better CSI can be obtained at BS
that is elaborate in user pairing
The BS transmits the superimposed mixture
119909119905 = ඥ1199051199041 + ඥ1 minus 1199051199042 ------------------------------- (3)
In which 1199561 and 1199562 are the unit of power signals received by users 1199321 and 1199322
respectively t is the power allocation coefficient for the adjacent user
1199031 = ℎ1119909119905ξ119875 + 1198991 ------------------------------- (4)
1199032 = ℎ2119909119905ξ119875 + 1198992 ----------------------------------(5)
Where 1199451119886119899119889 1199452 the channel profit link with the fading of small scale since the
BS to the user 1199321 and 1199322 respectively The additional Gaussian noise with variance
52
is denoted 1199511 119886119899119889 1199512 and zero mean 119894119904 119889119890119899119900119905119890119889119886119904 (1199250) and it is assumed
that the BS conveyed SNR is 120646 = 1199271199250
ൗ
In the NOMA technique additional users with more power may decode their signal
by recognizing the adjacent signal as noise without decoding the adjacent user
message In the previous equation 1198801 is supposed to first solve a weak signal by
decoding its own SIC signal1198802 which is an unauthenticated user attempted to
decrypt the nearer user text after decrypting the adjacent usage text after decoding
its own SIC message The following equation has therefore been achieved
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2 ----------------(6)
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2 ----------------(7)
119879119900119905119886119897119904119894119899119903 = 11987811986811987311987721 1198781198681198731198771
1 119878119868119873119877221198781198681198731198771
2 -----------------(8)
Where 119930119920119925119929119950119951
indicates the SINR ratio of user mth that was decoded by 119932119951 for
119898 119899 isin ሼ119894 2ሽ and the channels gain followed an exponential distribution with the
parameter 120649119950=120654120782120633119950minus120630
324 Problem formulation
As a result the BS could achieve and provide better communication for users who
are vulnerable to security threats from unauthenticated users the proposed
framework identified two kinds of QoS energy efficiency that could be considered
essential for addressing the problem In a particular study a pair of OPs was
specified to check the reliability at which the attainable data rate for users is equal
to or greater than the threshold of minimum reach The following issue aimed at
reducing the pair OP to an SOP factor intended for the user 119932120783 that is provided by
Where 1199270is Outage Probability- (OP)
1199271 is Secrecy Outage probability user U1 119930119926119927(119932120783) and
120631 the permissible SOP threshold
53
33 Performance Analysis Improving PLS Insecurity of NOMA
System
331 The Pair OP Calculation
Through Shannons capacity formula and assuming 119914120783119957119945 119886119899119889 119914120784
119957119945 as the
threshold capacities of users 119932120783 119886119899119889 119932120784 respectively the combination of OP
could be offered by
119927119954 = 120783 minus 119928120783119961119928120784 in which 120649119950 = 120784119940119950119957119945
119950 isin ሼ119946 120784ሽ -------------(9)
empty120783 =120649120784
120646(120783+119957+120649120784119957) empty120784 =120649120783
120646119957
119928120783 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ 120782 lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 ------------------------(10)
Case 1empty1 gt empty2 for having the limitation of the allocation of power factor (t)
required to be satisfied (tgt120649120783
120649120783+120649120784+120649120783120649120784) and for this case 119928120784 could be attained as
follows
119928120784 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ
120649120783
120649120783+120649120784+120649120783120649120784lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 --------------(11)
Case 2 empty1 lt empty2 Like case 1 it was stated that the opposite constraint depends
on
t gt 1206491
1206491+1206492+12064911206492 and 1199282 can be evaluated as follows
119928120784 = ൝119942119961119953 ቀ
minusempty120784
120649120783ቁ 120782 lt
120649120783
120649120783+120649120784+120649120783120649120784
120782 119952119957119945119942119955119960119946119956119942 ---------------------(12)
54
Table 31 List of parameters
Parameters Description
N Number of nearer users
M Number of far users
E Eavesdropper
ℎ119909119910 Channel coefficient between 119909119905ℎchannel and 119910119905ℎ users
119889119883119884 The distance among x and y
1198890 Space
120598 An exponent of the path loss
ℒ Attenuation of the received signal
120575119898 the range between the BS and the nodes
1205960 Path loss constant
120572 Path loss exponent
1199041 1199042 Unit of power signals received by users 1198801 and 1198802
T Power allocation factor for the adjacent user
ℎ1119886119899119889ℎ2 Channel coefficient of 1198801 and 1198802with the fading of small
scale
11989911198861198991198891198992 Gaussian noise variance
1198730 Zero mean for Gaussian noise
120588 Signal to noise ratio
119878119868119873119877119898119899
Signal to interference noise ratio of users n and m channels
55
120591119898 Exponential distribution parameters
1198750 Pair of OP
1198781198741198751 119878119874119875(1198801)
120573 The permissible SOP threshold
Table 31 depicts the list of parameters used in the proposed methodology which
are useful for assigning and the values are assigned based on the parameters given
for the experimental evaluation as well This chapter concludes with the basic and
the actual flow of the proposed method to know more about the work in the
simulation process
332 Pseudo-code for the proposed algorithm
Algorithm I
Step 1 Estimate Rayleigh distribution
119862119873(0 120575119898minus120572 2Τ
1205961199001 2Τ
) where
120633119950 is the distance between nodes 119932119950 and the BS
120630 is the path-loss exponent and
120654119952 is the path-loss constant
Step 2 The BS broadcasts the superimposed mixture and input signal as follows
119909119905 = ξ1199051199041 + ξ1 minus 1199051199042
Where 119956120783 and 119956120784 are the unit power signals received by users 119932120783 and 119932120784
respectively 119957 is the Power allocation coefficient for the near user
Step 3 The received signal is as follows
1199031 = ℎ1119909119905ξ119875 + 1198991
1199032 = ℎ2119909119905ξ119875 + 1198992 where
56
119945120783 and 119945120784 are the channel gain associated with the
small-scale fading from the BS to users 119932120783 and 119932120784 respectively
1199511 and 1199512 are the additive white Gaussian noise with zero mean and variance
119925120782
Step 4 the BS transmit signal-to-noise ratio (SNR)
120646 = 119927119925120782
Step 5 Signal-to-Interference-plus-Noise-Ratio (SINR) for the two users 119932120783
decodes the signal of the weak user first then decodes its own signal after using
SIC 119932120784 is an untrusted user and tries to decode the near user message after
decoding its own message using SIC
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588ൗ and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ2ȁ2+1120588ൗ and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2
119879119900119905119886119897119904119894119899119903 = ሼ11987811986811987311987721 1198781198681198731198771
1 11987811986811987311987722 1198781198681198731198771
2ሽ
where 119930119920119925119929119950119951
is the signal-to-interference-plus-noise-ratio (SINR)
of user 119950th decoded by 119932119951 for 119898 119899120598ሼ119894 2ሽ and ȁ119945119950ȁ2 is the
channels gain of 119932119950
Algorithm II
Partially observable Markov decision process
Step 1 Prediction of the maximum capacity of channel with respect to the data rate
119955119943 = 119877(119878119909119863)
S is denoted as states
Let D be the channel characteristics which are considering here as actions
Reward function R
Step 2 The agent receives an observation 119900120598120118which depends on the new state of
the environment 119930prime and on the just taken action 119941 with probability
119926(119952ȁ119956prime 119941)
Step 3 Reward earned at time t is expressed as
57
119903119891119905 = 119877(119878119909119863)119905
Step 4 reward function on belief states
119919 is the belief states over POMDP states
119919119943 is the belief state transition function
119955119943 = 119877(119867119909119863)
Step 5 The reward function is updated based on the belief MDP the agent only
cares about which action will yield the largest expected immediate reward ie the
maximum capacity channel
119861119891 ቀℎ 119889 ℎprimeቁ = 119875119903 (
119900120598120118
ℎprimeȁℎ 119889 119900) 119875119903(119900ȁ119889 ℎ) 119861119891
119875119903(ℎprimeȁℎ 119889 119900) = ቄ1119894119891119905ℎ119890119887119890119897119894119890119891119906119901119889119886119905119890119908119894119905ℎ119886119903119892119906119898119890119899119905119904ℎ 119889 119900119903119890119905119906119903119899119904ℎprime
0119900119905ℎ119890119903119908119894119904119890
119903119891(ℎ 119889) = σ ℎ(119904)119877(119904 119889)119904isin119878
34 SUMMARY
The NOMA-UAV communication framework has been proposed in this research
work and the Physical Layer security aspect has been focused on for optimization
The PLS performance metrics selected are SOP amp Pair OP in the proposed system
model The POMDP framework is general enough to model a variety of real-world
sequential decision-making problems Applications include robot navigation
problems machine maintenance and planning under uncertainty in general Here
we have adopted the User pairing POMDP algorithm for resource allocation in two
users amp multi-user NOMA-UAV communication networks The proposed study has
been evaluated using performance measures by varying distances of trusted amp
untrusted users from the base station as well as for varying SINR conditions The
simulation results and outcomes are discussed in a further chapter
58
CHAPTER 4
RESULT AND DISCUSSION
41 PERFORMANCE MEASURES OF SECURED NOMA-
UAV COMMUNICATION MODEL
Drones or UAV-based communication technology has been thoroughly studied and
adopted by the 3GPP standard UAV systems have been envisaged to form an
integral part of future wireless communication applications due to their dynamic
flexible and flying nature Due to their ability to reach higher altitudes they usually
have dominant LOS channels with the ground nodes This capability can be used to
provide confidentiality to the legitimate receivers against the eavesdroppers This
can be done by deploying UAVs to launch more effective jamming signal attacks
to terrestrial eavesdroppers The conventional cooperative jamming schemes make
an assumption that the locations of terrestrial jammers are fixed which might
compromise the secrecy of the system if the jammers are located far away from the
eavesdroppers and is also not practical as it makes an assumption of perfect CSI of
the jammer to eavesdropper channel
Here in the proposed scenario of the NOMA-UAV communication network two
key PHY layer security metrics SOP amp Pair Outage Probability have been jointly
optimized for a more effective power allocation factor for NOMA cellular
architecture The varying channel characteristics have been analyzed to achieve the
desired SOP with the constrained threshold minimum target secrecy rate for the
two-user scenario POMDP Algorithm iteratively provides the optimized SINR that
has been used to keep trusted users in pair with the untrusted user with minimum
achievable outage probability
The proposed NOMA-UAV System model has been simulated in MATLAB 2019b
version with mainly Communications System Toolbox Optimization Toolbox RF
Toolbox Signal Processing Toolbox Statistics and Machine Learning Toolbox
The simulation has been carried out for two-user pair to achieve desired secrecy
target rate and feasible pairing between trusted user amp untrusted user(eves-dropper)
59
The optimal-outage performance of minimized pair OP subjected to SOP constraint
has been solved by both dynamic programming optimization and POMDP
optimization approaches
The simulation of the proposed framework for the UAV-NOMA communication
network has been carried out and discussed in two parts two user models and a
multi-user model as below mentioned discussion The base station is deployed at
the center of a cell of radius 1000 m There are two users in the system under
consideration The channel between two nodes in the system suffers both the small-
scale fading and path loss effect Small-scale fading follows the exponential
distribution with the mean value 1 The noise signal of all channels has a Gaussian
distribution with 0 mean and variance 1 The path loss exponent α and the path loss
constant PLo are set to 2 and 01 respectively We assume a normalized bandwidth
of 1 Hz The SOP constraint threshold is assumed 01 and the target secrecy rate is
001 The power allocation coefficient is 015 and the BS transmitted SINR is
assumed 15dB for the proposed model As per the NOMA transmission scheme
SINR has been obtained for User 1 amp User 2 both for SIC decoding POMDP
algorithm optimally tunes the SINR value for User 1 amp User 2 that is considered to
select optimal power allocation coefficient for both trusted and untrusted users with
respective SOP of User1
42 Numerical results and Discussion
Table 41 Simulation Parameters
Parameters Values
Untrusted user Distance (d2) 200-1000 (300 700)
BS transmit signal-to-noise ratio (SNR) (120588) in dB 15
Sop constraint constant threshold (β) 01
Power allocation factor (t) 015
Trusted User distance (d1) 2-
60
Cell Radius (rd) 1000 meters
Path loss exponent (α) 2
Path loss constant (PLo) 01
Normalized bandwidth in Hz 1
Target secrecy rate (Rs) 001
No of Bits 100
Pair Outage Probability (P0) 05250
SINR 5319 15305 5162
10247
421 Feasible amp Infeasible pairing of trusted amp Untrusted users
In this section the CSI value broadcasted by Base Station is assumed 15 dB initially
and for varying channel conditions various SINR values of 120646 = minus20 minus10 20 dB
is described with target secrecy rate 0005 and 001 for power allocation coefficient
015 and User 1 distance at 200m is shown in the Figure 41 below
Figure 41 Impact on Sop with increase distance between BS and user U2
61
Varying target secrecy rate threshold from 0005 to 001 the obtained result in
Figure 42 revealed that the 1199321 is a gradually reducing function for the distance of
untrusted user d2 that implies that the increasing value of d2 leads to the
improvement of the SOP of 1198801
Figure42 Impact on Sop with increase distance between BS and user U2
Since the offered constant threshold 120656 in SOP limit1199322 which should be located at
a larger space when compared with a value of threshold to attain the SOP of 1199321
apart from that it is expected the high target secrecy rate maximizes the SOP of 1199321
Here in below figure the power allocation coefficient has been varied from 0 to 1
with threshold value of t and the desired t_sop for feasible pairing
Figure 43 Feasible pairing t Vs pair OP
62
Pair OP in case of rising 1199322 untrusted user in d2 for different BS transfer the SNR
where t= 015 and d1=200mThe infeasible pairing of SOP (1199321) and the OP pair
by the enhanced allocation of the power (t) d1 (200m) d2 (300m) 120646 = 15 dB and
120656 = 0
Figure 44 shows the identical plotting of data by adjusting the unauthenticated
level of the user through converting it to a BS closer distance (d2=300m) Accuracy
is compared and checked with the full spectrum of numerical simulations The
result has shown that the effectiveness is based on a comparative study of the two
consumers of the BS
Figure 44 Infeasible pairing t Vs pair OP
422 The Secrecy Outage Probability amp Pair Outage Probability
Feasible paring in the SOP of pair OP and 1199321 with the improved power allocation
factor t in which d2=700m d1=200m 120646 = 15119889119861 and The result described that
the OP and SOP of the user 1199321 with increased for two various distances of the 1199322
untrusted user The simulation result approves the convex nature 120656 = 0 1of the OP
and the SOP is sequentially decreased depending on t Generally when it enhances
the power owed to the weak user text reduces that develop the ability of 1198802 for
discerning the superior positioned signals therefore enhancing the SOP of 1198801
63
Figure 45 Secrecy outage probability
Figure 46 Pair outage probability
423 SNR versus Strictly Positive Secrecy Rate
Figure 47 proved that the potential for confidentiality is superior to the existing
techniques The proposed application for pre-coding improves the efficiency of the
device The transmission power of the system is the power needed for the
transmission of particular data
64
Figure 47 SNR versus Strictly positive secrecy rate
If there is a growth in the number of users there is a risk of inference in the
transmission of data and thus the reliability of the data rate may be affected Based
on these cases the efficiency of the antenna power to be withheld and occupy the
data determined
424 Power radiated by per MMBs antenna
In the case of multi-users scenario when there are more than two users then the
allocation of an optimized resource block to all users is the key parameter to achieve
desired outage efficiency because strong users require higher SNR for higher data
rates and weak users are allocated minimum threshold SNR for lower data rate
requirements to maintain suitable pairing OP and SOP balance
Figure 48 Power radiated by per MMBs antenna
65
So the POMDP policy optimization has shown better performance over the
dynamic programming approach particularly when more users are active (a greater
number of antennas as in Figure 48 the overall radiated power per BS antenna in
downlink has been considerably reduced
43 CONCLUSION AND SCOPE OF FUTURE WORK
431 Conclusion
Starting with LTE (4G) OFDMA has replaced WCDMA with mobile cellular
communications and will also be used during advanced 5G while Non-Orthogonal
Multiple Access (NOMA) has recently been recognized as a groundbreaking PHY
technology in UAV communication NOMA scheme is used in place to increase the
effective use of small resources such as in UAV communication where the data rate
is very low and critical decision making is of utmost importance
The critical need for UAV communication is a secure PHY layer for mission-
critical applications and as NOMA doesnrsquot promise high security the proposed
research work has been carried out to enhance the insecurities of NOMA-UAV
communication In this proposed research work the probabilities of confidential
outage (SOP) and OP were investigated in the two-user NOMA system Here BS is
required to pair a trusted or permissible user with other untrusted users due to the
unequal distribution of untrusted and trusted users in the cell The SIC is then
applied to the receiver side intended for decoding the message signals The Pair OP
of both users has been analyzed for varying Target Secrecy Rate (Rs) of the trusted
user U1 which provides constraint threshold of the SOP of U1
By varying the distance of Untrusted users from BS the optimal distance and power
allocation factor for the feasible pairing of trusted and untrusted users without
compromising the secrecy outage probability of U1 has been achieved in simulation
results
POMDP has provided the optimal power allocation as a resource allocation
algorithm in the dynamically changing environment of two user NOMA cases
where the distance between BS and untrusted user varies significantly The
performance of secure NOMA-UAV is affected critically by (SOP of User 1) which
66
should be optimally selected to maintain the proposed Pair OP between both users
and the simulation results have supported this optimal outage performance Thus
NOMA-UAV architecture has the potential of providing a secure PHY layer for
mission-critical applications by opting for suitable decision-making resource
algorithm POMDP
431 Scope of Future Work
Furthermore the multiuser scenario with the increased number of Untrusted users
can be analytically verified and simulated in the same direction for NOMA-UAV
communication to improve transmission security and reliability In addition more
adaptive and efficient Resource allocation algorithms for NOMA-UAV networks
with secured performance in real-time applications should be investigated
1
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Qin Z Liu Y Ding Z Gao Y amp Elkashlan M (2016) Physical layer security
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Rajakaruna A Manzoor A Porambage P Liyanage M Ylianttila M amp
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7
Rashid A Sharma D Lone T A Gupta S amp Gupta S K (2019) Secure
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Shang B Liu L Ma J amp Fan P (2019) The unmanned aerial vehicle meets
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8
Sun X Yang W Cai Y Ma R amp Tao L (2019) Physical layer security in
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Uddin M A Mansour A Jeune D L Ayaz M amp Aggoune E-H M (2018)
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11
PUBLICATIONS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495449|P a g e
Migration from 4g LTE to Advanced PHY Techniques for
Unmanned Aerial Vehicle (UAV) Communication
Pankaj Patel PHD StudentGujarat Technological UniversityGujarat India
ABSTRACT
UAV (unmanned aerial vehicles) with their high mobility and low cost have found a wide range of applications
during the past few decades Historically UAVs have been primarily used in the military mainly deployed in
hostile territory to reduce pilot losses With continuous cost reduction and device miniaturization small UAVs
are now more easily accessible to the public hence numerous new applications in the civilian and commercial
domains have emerged For the sake of boosting resilience against faults natural disasters and unexpected
traffic the Unmanned Aerial Vehicle (UAV) assisted wireless communication systems can provide a unique
opportunity to cater for such demands in a timely fashion without relying on the overly-engineered cellular
network However for UAV-assisted communication issues of capacity coverage and energy efficiency are
considered of paramount importance Starting with LTE (4G) Orthogonal Frequency Division Multiple Access
(OFDMA) has replaced WCDMA for cellular mobile communications and it will also be employed in advanced
5G yet Non-orthogonal multiple access (NOMA) has been recently recognized as a promising PHY technique
to significantly improve the spectral efficiency of mobile communication networks In this paper we provide an
overview of UAV-aided wireless communications by introducing the basic networking architecture
highlighting the key design considerations as well as the new opportunities to be exploited
Keywords LTE (4G) Non-orthogonal multiple access (NOMA) Unmanned Aerial Vehicle (UAV) Wireless
communication
----------------------------------------------------------------------------------------------------------------------------- ---------
Date Of Submission 26-04-2019 Date Of Acceptance 06-05-2019
----------------------------------------------------------------------------------------------------------------------------- ----------
I INTRODUCTION The use of unmanned aerial vehicles
(UAVs) will grow rapidly in the next decade These
remotely piloted or preprogrammed aircraft are
envisioned for applications in numerous civil
settings including industrial monitoring scientific
data gathering agriculture public safety and search
and rescue Many other applications - presently
unforeseen - will inevitably also arise These
vehicles also known as the unfortunate misnomer of
drones must be integrated into the national
airspace system and into the airspace worldwide A
natural concern in the use of UAV is safety and this
has direct implications for the control and non-
payload communication systems that must be used
to operate it efficiently Similarly navigation and
surveillance functions must be made more reliable
and more accurate Because of these factors many
UAV research development testing and
standardization efforts are underway by
governments industries and academia Despite the
fact that piloted civil aircraft have been flying safely
for decades UAV presents distinct new challenges
in the form of different flight profiles eg low-
elevation flights and more high-dynamic maneuvers
wider required bandwidths eg for video and
different ground site characteristics such as locations
in cluttered areas and lower elevation antennas
In this paper first the evolution of radio
technologies considered in UAV wireless
communication is reviewed in literature survey and
the significant work in the area is highlighted along
with the newest challenges The reminder of this
paper is organized as follows
The promising technology NOMA and its
variants are discussed in section three In Section
four the system model and assumptions are
presented and in section five the comparative
analysis of NOMA with existing popular technology
OFDMA (OMA) is given with simulation
persormance analysis At last the work is concluded
in section five
II LITERATURE SURVEY Drones variously known as unmanned
aerial vehicles (UAVs) unmanned aerial systems
(UAS) or remotely piloted aircraft system (RPAS)
are used in several parts of the world for surveying
and aerial mapping disaster management work
monitoring crop production and infrastructure
activities besides commercial photography and
courier delivery The viability of UAV as a
multipurpose research vehiclehas driven great
RESEARCH ARTICLE OPEN ACCESS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495450|P a g e
interest since recent decades[1] The
basictechnology building blocks responsible for the
current advancesinclude airframes propulsion
systems payloadssafety or protection systems
launch and recovery dataprocessor ground control
station navigation and guidanceand autonomous
flight controllers The following briefsurvey is
focused on the area of navigation guidance
andcontrol of UAVs Various control design for
UAVs has beenproposed ranging from linear to
nonlinear synthesis timeinvariant to parameter
varying and conventional PID tointelligent control
approaches The developed controllershave been
implemented for different aerial platforms
airship(blimp) fixed-wing UAV small scale
helicopteruad-rotors and MAV Wireless
communication systems that include unmanned
aerial vehicles promise to provide cost-effective
wireless connectivity for devices without
infrastructure coverage Compared to terrestrial
communications or those based on high-altitude
platforms on-demand wireless systems with low-
altitude UAVs are in general faster to deploy more
flexibly reconfigured and likely to have better
communication channels due to the presence of
short-range line-of-sight links However the
utilization of highly mobile and energy-constrained
UAVs for wireless communications also introduces
many new challenges In India for the regulation
and safety purpose in commercial and survilence
applications the policy guideliens also introduced
as below
Table 1UAV communication Policy Guidelines for
commercial and surveillance purpose
III MIGRATION FROM 4G LTE TO 5G The fruitful deployment of UAV based
communicationsystems for 4G and beyond future
wireless networks is highlyinvolved in finding joint
solutions to challenge of ubiquitousconnectivity with
both a multitude of devices in a spectralefficient way
as well as with energy-efficient transmissionand
operation of the UAV-BS for maximized and
armonizedcoverage and capacity [2][3] It should be
noted that suitableenergy efficiency for the UAV-
assisted ommunication systemachieves paramount
importance in the overall performance ofthe system
Efficient energy consumption results in
enhancedairtime for the communication system
improving bitsJoulesfor a given energy level
Furthermore coverage and capacityof an aerial cell
are attributed to many factors such as
thetransmission power antenna gains UAV
altitude deploymentenvironment and prominently
radio access technology [4]
4G is the fourth generation of broadband
cellular network technology succeeding 3G and
besides the popular techniques in 3G4G ie
TDMAWCDMAOFDMA a new radio access
technology NOMA is also developed by researchers
to be used in communication networks due to its
capability in increasing the system capacity
Recently non-orthogonality based system designs
are developed to be used in communication
networks and have gained significant attention of
researchers Hence multiple access (MA) techniques
can now be fundamentally categorized as orthogonal
multiple access (OMA) and non-orthogonal
multiple access (NOMA) In OMA each user can
exploit orthogonalcommunication resources either
within a specific time slot frequency band or code in
order to avoid multiple access interference The
previous generations of networks have employed
OMA schemes such as frequency division multiple
access (FDMA) of first generation (1G)time
division multiple access (TDMA) of 2G code
division multiple access (CDMA) of 3G and
orthogonal frequency division multiple access
(OFDMA) of 4G
In NOMA multiple userscan utilize non-
orthogonal resources concurrently by yielding a high
spectral efficiency while allowing some degree of
multiple access interference at receivers Recently
NOMA reputations have climbedsharply as a
fundamental solution to the challenges
encompassingthe next generation wireless networks
[5][6]NOMA has been proved to exhibit improved
spectral efficiencybalanced and air access as
compared to OMAtechnologies[6] with the ability
to cater for multipledevices in the same frequency
time or code resource thusproviding efficient access
to massive connected devices Furthermore NOMA
is also instrumental in reducingthe interference by
employing orthogonal resources as inOrthogonal
Frequency Division Multiple Access
(OFDMA)[7][17] or by sharing a single beam
between multiple users forintra-cluster access and
using NOMA for inter-cluster access[18]Current
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495451|P a g e
studies have focused on provisioning Air to
Ground(A2G) communication services mainly
through placement op- timization under various
viewpoints in literature The performance of UAV
based communication systems hasalso been
addressed for the underlaid Device to Device(D2D)
deployment scenario This work assumed
interferenceraised by D2D network nodes without
considering the presenceof terrestrial BS
Additionally there have been a fewstudies
discussing the performance of NOMA for UAV
basedcommunication system[8] A NOMA enabled
fixedwingUAV deployment was proposed in [8] to
support coveragefor ground users situated outside
BS offloaded location
In general NOMA schemes can be
classified into two types power-domain
multiplexing andcode-domain multiplexing In
power-domain multiplexing different users are
allocated[7][8][9][6][5][1][10] differentpower
coefficients according to their channel conditions in
order to achieve a high systemperformance In
particular multiple usersrsquo information signals are
superimposed at the transmitterside At the receiver
side successive interference cancellation (SIC) is
applied for decoding thesignals one by one until the
desired userrsquos signal is obtained providing a good
trade-offbetween the throughput of the system and
the user fairness In code-domain multiplexing
different users are allocated different codes and
multiplexed over the same time-frequencyresources
such as multi-user shared access (MUSA) sparse
code multiple access (SCMA) and low-density
spreading (LDS) In addition to power-domain
multiplexing and codedomain multiplexing there are
other NOMA schemes such as pattern division
multiple access(PDMA) and bit division
multiplexing (BDM) Although code-domain
multiplexinghas a potential to enhance spectral
efficiency it requires a high transmission bandwidth
andis not easily applicable to the current systems
On the other hand power-domain multiplexinghas a
simple implementation as considerable changes are
not required on the existing networksAlso it does
not require additional bandwidth in order to improve
spectral efficiency Inthis paper the prime focusis on
the power-domain NOMAAlthough OMA
techniques can achieve a good system performance
even with simple receiversbecause of no mutual
interference among users in an ideal setting they
still do not have theability to address the emerging
challenges due to the increasing demands in future
networks andbeyond
The superiority of NOMA over OMA can
besummarized as follows
_ Spectral efficiency and throughput In OMA such
as in OFDMA a specific frequencyresource is
assigned to each user even it experiences a good or
bad channel conditionthus the overall system suffers
from low spectral efficiency and throughput In
contrary inNOMA the same frequency resource is
assigned to multiple mobile users with good and
bad channel conditions at the same time Hence the
resource assigned for the weak user isalso used by
the strong user and the interference can be mitigated
through SIC processesat usersrsquo receivers Therefore
the probability of having improved spectral
efficiency and ahigh throughput will be considerably
increased
_ User fairness low latency and massive
connectivity In OMA for example in OFDMAwith
scheduling the user with a good channel condition
has a higher priority to be servedwhile the user with
a bad channel condition has to wait to access which
leads to a fairnessproblem and high latency This
approach cannot support massive connectivity
HoweverNOMA can serve multiple users with
different channel conditions simultaneously
thereforeit can provide improved user fairness lower
latency and higher massive connectivity
_ Compatibility NOMA is also compatible
with the current and future communication
systemssince it does not require significant
modifications on the existing architecture For
exampleNOMA has been included in third
generation partnership project long-term
evolutionadvanced (3GPP LTE Release 13)
Figure 1Pictorial comparison of NOMA Vs OMA
Although NOMA has many features that
may support next generationsit has some limitations
that should be addressed in order to exploit its full
advantage set Thoselimitations can be pointed out
as follows In NOMA since each user requires to
decode thesignals of some users before decoding its
own signal the receiver computational
complexitywill be increased when compared to
OMA leading to a longer delay Moreover
informationof channel gains of all users should be
fed back to the base station (BS) but this results in
asignificant channel state information (CSI)
feedback overhead Furthermore if any errors
occurduring SIC processes at any user then the error
probability of successive decoding will beincreased
As a result the number of users should be reduced to
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495452|P a g e
avoid such error propagationAnother reason for
restricting the number of users is that considerable
channel gain differencesamong users with different
channel conditions are needed to have a better
network performance
IV NOMA UPLINK AND DOWNLINK
SCENERIO SIMULATION ANALYSIS In this section an overview of NOMA in
downlink and uplink networks is introduced
throughsignal-to-interference-and-noise ratio (SINR)
and sum rate analyses Then high signal-to-
noiseratio (SNR) analysis has been conducted in
order to compare the performances of OMA
andNOMA techniques[10]
A Downlink NOMA Network
At the transmitter side of downlink NOMA
network as shown in Fig 2 the BS transmits
thecombined signal which is a superposition of the
desired signals of multiple users with different
allocated power coefficients to all mobile users At
the receiver of each user SIC process isassumed to
be performed successively until userrsquos signal is
recovered Power coefficients ofusers are allocated
according to their channel conditions in an inversely
proportional mannerThe user with a bad channel
condition is allocated higher transmission power
than the one which has a good channel condition
Thus since the user with the highest transmission
power considers the signals of other users as noise
and recovers its signal immediately without
performing anySIC process However other users
need to perform SIC processes In SIC each userrsquos
receiverfirst detects the signals that are stronger than
its own desired signal Next those signals
aresubtracted from the received signal and this
process continues until the related userrsquos own signal
is determined Finally each user decodes its own
signal by treating other users with lower
powercoefficients as noise The transmitted signal at
the BS can be written as
s = aiPsxi
L
i=1
where xi is the information of user i (Ui)
with unit energy Ps is the transmission power atthe
BS and ai is the power coefficient allocated for user
i subjected to ai = 1Li=1 and a1gea2gehellip geaL since
without loss of generality the channel gains are
assumed to be ordered as h1 2 le h2 2 le⋯ hL 2 where hL is the channel coefficient of Lth
user based on NOMAconcept The received signal
at lth user can be expressed as follows
y1 = hls + nl = hl aiPsxi + nlL
i=1
where nlis zero mean complex additive Gaussian
noise with a variance of σ2
(1) SINR analysis By using (2) the instantaneous
SINR of the lth user to detect the jth user jle l
with jne L can be written as
SINRl = alγ hl 2
γ hl 2 aiLi=l+1 + 1
Where γ = Psσ2 denotes the SNR
(2) Sum rate analysis After finding the SINR
expressions of downlink NOMA the sumrate
analysis can easily be done The downlink
NOMA achievable data rate of lth user can
beexpressed as
RlNOMA-d
= log2 1 + SINRl = log2(1 +alγhl2γhl2 i=l+1Lai+1
B Uplink NOMA Network
In uplink NOMA network as depicted in
Fig 3 each mobile user transmits its signal to the
BS At the BS SIC iterations are carried out in order
to detect the signals of mobile users By assuming
that downlink and uplink channels are reciprocal and
the BS transmits power allocation coefficients to
mobile users the received signal at the BS for
synchronous uplink NOMA can be expressed as
r = hi aiPxi + n
L
i=1
where hi is the channel coefficient of the ith
user Pxi is the maximum transmission power
assumed to be common for all users and n is zero
mean complex additive Gaussian noise with a
variance of σ2
Figure 2Downlink NOMA network
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495453|P a g e
Figure 3 Uplink NOMA network
1) SINR analysis The BS decodes the signals of
users orderly according to power coefficientsof
users and then the SINR for lth user l ne 1 can
be given by
SINRl =alγ hl 2
γ ai hi 2 + 1lminus1i=1
where γ =P
σ2
2) Sum rate analysis The sum rate of uplink
NOMA when γ minus infincan be written as
Rsum NOMA-u asymp log2(γ hl 2L
l=1
C Comparing NOMA and OMA
The achievable data rate of the lth user of OMA for
both uplink and downlink can be expressed
RsumOMA = αl log2(1 +
βlγ hl 2
αl)L
l=1
For the sake of simplicity sum rates of
uplink NOMA and OMA can be compared for
twousers Then using both the sum rate of uplink
NOMA and OMA at high SNR can beexpressed
respectively as
RsumNOMAasymp log2 γ h1 2 + γ h2 2
Here we notice ROMA
sumle RNOMA
sum
Fig shows that NOMA outperforms OMA in terms
of sum rate in both downlink and uplinkof two
user networks
V SIMULATION RESULTS
The Comparative analysis of modelling
Downlink and Uplink NOMA in comparison with
OMA is simulated and findings are presented that
shows superiority of NOMA over OMA with better
spectral efficiency for simulation parameters taken
as power allocation coefficients a1=06 a2=04 and
channel responses h1 2
=0 DB h22=20 DB
parameters
Figure 4NOMA UPLINK
Figure 5 NOMA DOWNLINK
VI CONCLUSION This paper investigated an account of
NOMArsquos applicability for UAV-assisted
communication systems NOMA schemes are
proposed to improve the efficient usage of limited
network sources OMA based approaches that use
time frequency or code domain in an orthogonal
manner cannot effectively utilize radio resources
limiting the number of users that can be served
simultaneously In order to overcome such
drawbacks and to increase the multiple access
efficiency NOMA technique has been recently
proposed Accordingly users are separated in the
power domain Such a power domain based multiple
access scheme provides effective throughput
improvements depending on the channel conditions
The crucial need of UAV communication of
optimum utilization of available licensed spectrum
bandwidth is considered here and simulation results
taken presented that NOMA performs better than
OMA while fulfilling individual user-rate constraint
for both users The research work can be further
carried out investigating joint power and phase
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495454|P a g e
allocation of UAV nodes deployment for efficient
operations
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[16] T R a Z H Z Chang Queueing game for
spectrum access in cognitive radio networks
IEEE Communications Letters vol 19 no 11 pp
2017-2020 June 2015
[17] Z C L T R a Z H F I Yun Hu Service
Provisioning and User Association for
Heterogeneous Wireless Railway Networks IEEE
Transactions on Communications 2017
[18] H S W Tianti Chen Optimal Scheduling for
Wireless On-Demand Data Packet Delivery to
High-Speed Trains IEEE Transactions on
Vehicular Technology vol 64 no 9 pp 4101 -
4112 september 2015
Pankaj Patel Migration from 4g LTE to Advanced PHY Techniques for Unmanned Aerial
Vehicle Communication International Journal of Engineering Research and Applications
(IJERA) Vol 09 No04 2019 pp 49-54
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Improving Of Physical Layer Insecurity Of The
Non Orthogonal Multiple Access System
Pankaj M Patel Prof Dr Chetan B Bhatt
Abstract The key aspect of the NOMA (power domain non orthogonal) is the user possibility for decoding the messages belonging to another pair users
on similar resources The method interprets a security threat especially in the case where the base station serves the users with various security
clearance or untrusted users The main aspect of NOMA is to serve the multiple users upon the similar radio resources at the minimal inter user
interference expense The system not only permits the serving of particular users with high efficient bandwidth but also permits the scheduling more type
of users than the timely available users In this study we investigated the secrecy outage probability (SOP) and OP in the both two user and multi user
NOMA system where the BS is supposed to pair a trusted or legitimate user with other untrusted users because of the un even distribution of the
untrusted and trusted users in the cell SIC the successive interference cancellation was then implemented at the receiver side for decoding the
message signals With the application of NOMA concept the study investigated the pair outage behavior under the SOP constraints on the trusted users
In specific the SOP and OP of the concerned U1 were obtained in the closed type of expressions The study also provided the understanding the
possibility of obtaining an optimal outage efficiency for pairing under the SOP constraints With certain numerical simulations the study verified the
effectiveness of the analytical derivations with respect to various scenarios
Index Terms NOMA Secrecy outage Probability Successive Interference Cancellation bandwidth channel state information etc
mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash
1 INTRODUCTION The physical layer security and non-orthogonal multiple
access was regarded as the encouraging techniques for the
processing of wireless communication network systems Today
the combination of the two significant communication methods
was studied to guarantee a spectral efficient and secure
wireless transmission Most of the prevailing works
predominantly concentrated on the optimization and efficiency
of the PLS in the existence of untrusted relay nodes and
external eavesdroppers(Arafa et al 2019a)But there occurs a
gap in the theoretical studies to describe the ease of obtaining
the enhanced efficiency in the existence of untrusted users
Recently the network traffic amount have greatly enhanced
particularly with the updated growth in IoT applications in
future To rectify the huge traffic demand upcoming wireless
networks must deliver a best spectral effectiveness and large
connectivity (Sun et al 2018) NOMA is regarded as the best
technology in which various NOMA technique exhibit similar
concept of providing several users at the similar frequency and
time The famous NOMA types are code domain and power
domain that provided enhanced efficiency when compared
with the existing techniques The paper adopted the power
domain on the basis of super position coding (transmitter side)
at the SIC (receiver side) Hence the users could possess the
key for the messages of other users and thereby utilize SIC for
removing the interference (Cao et al 2019) (Zhao et al
2018) Hence various NOMA methods was proposed for
allowing the adjacent users to perform as a relay for improving
the efficiency of the weak users through the resending of
decoded data in a next time slot The weak user could utilize
the MRC technique to integrate the information achieved in
different time slots In addition obtaining a secured
communication is a crucial problem over the vulnerable
wireless networks to security threats mainly because of the
broadcasted transmission nature
The study investigated the secrecy performance and outage
with the untrusted user(Furqan et al 2019) The main aspect
of the study is to analyze the feasibility of achieving the OP of
the pair under a trusted user Because of the decoding facility
and spectrum sharing of SIC the untrusted user could perform
as a eavesdropper
Figure 1 Representation of Base station
Figure 1 depicts the representation of base station The main
aim of the proposed system defined as
bull To investigate the outage probability of the proposed
system
bull To investigate the SOP of the proposed system
bull To derive the accurate expression of the outage
probability for all kind of scenarios and closed form of
expressions for few special cases and verifying them
numerically for yielding a better outage efficiency
2 RELATED WORKS This section describes the different existing techniques and
methods related as our proposed system (Cao et al
2019)suggested two kinds of relay selection process denoted
as AF (amplify and forward) and DF (decode and forward) on
the basis of AORS and DORS for achieving secure and
reliable NOMA systems under the untrusted users The study
derived the accurate and asymptotic closed form of the SOP
expressions and the PSCP obtained by the two methods and
investigated the optimized feature of the two methods The
____________________________________
bull PANKAJ M PATEL is currently pursuing PHD program in Electronics
amp Communication in Gujarat Technological University E-mail
pankajmphd24gmailcom
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complete analysis and the simulation results represented that
both the AORS and DORS characteristically outperformed the
benchmark system apart from obtaining the similar SOP and
the required PSCP at very high Signal to noise ratio (Zhang et
al 2018)Investigated the power allocation and joint subcarrier
issue for NOMA ndashAF two-way relay networks with restrictions
The study focused to optimize the obtainable secrecy
efficiency by designing jointly the SC task power allocation
and user pair scheduling The paper suggested a SCAS-1
technique by assuming the appropriate information about the
channel state information in the relay station followed by the
formulation of SCAS-2The secured power allocation issue is
structured as a convex programming issue and then resolved
by in-depth point techniques The results of simulation
explained that the efficiency of the suggested SSPA algorithms
with and without CJ respectively (Arafa et al
2019b)Considered a downlink system where the base station
is connecting with two appropriate users in two various
scenarios in the unsecured environments which are the
presence of the eavesdropper and untrusted relay
communication In the first process several trusted
cooperative relays is engaged for assisting with the base
station transmission and protect the corresponding signals
from the eavesdropper Several relay methods are framed and
investigated for the following process which are forward and
decode cooperative jamming and AFFor all the technique
secured beam forming signals were formulated at the relays
for maximizing the obtainable secret rate areas For the next
process with untrusted relay the obtained secrecy rate areas
obtained for two various relay schemes which are AF and CF
under two various operation modes In the first process the
prescribed users will receive the signals from the untrusted
relay and the base station for decoding the messages The
study depicted that the efficient relay scheme is highly
dependent on the parameters of the system especially the
nodal distance and the secrecy rate area (Sun et al
2018)Studied the algorithm for resource allocation for MISO
systems where the full duplex BS serve several half duplex
downlink and uplink users on the similar subcarrier The
allocation of the resource have been optimized for maximizing
the weight system output whereas the leakage of information
was restricted and an artificial noise was induced for granting
secured communication with respect to potential
eavesdroppers The study formulated a novel non-convex
optimization issue by considering the imperfect CSI of the
channels and requirements of QoS of legitimate users The
simulation results stated the efficiency of the optimal algorithm
was related to the suboptimal algorithm Apart from that the
suggested MISO NOMA technique not only guarantee uplink
and downlink communication purpose for security but delivers
a characteristic rate of system secrecy when compared with
the conventional MISO and other two baseline methods
(Dang et al 2017)Analysed the outage efficiency of various
multicarrier relay selection techniques for 2 hop OFDM system
in Poisson relay fields The study concentrated on DF relay
systems with more selection schemes The accurate
expressions for the OP are provided in integrals generally
Apart from that asymptomatic derivatives for OP in the SNR
region in the fixed circle area are predicted for both relay
selection techniques in closed forms Consequently several
significant factors that are linked to the cooperative network
were examined comprising OP ratio of two selection
techniques diversity and subcarrier optimization output In
conclusion a structure to analyze the OP of OFDM with
spatially random relay have been constructed that could be
easily altered for analyzing same case with various forwarding
protocols channel conditions and location distributors (Dang
et al 2018)Proposed a full duplex OFDM ndashD2D system in two
hop network where DF relays help the transmission from DUE
transmitter to DUE receiver The study also investigated the
OP issue by integrating the transmit power within the DUE
relays and transmitter and to deliver a suboptimal solution that
can improve the outage performance The investigations are
validated by Monte Carlo simulations These results described
could furnish an insight into full duplex OFDM system and
guides for the application in the next generation network
(Kokshoorn et al 2016) suggested a robust channel algorithm
for mmWave systems on the basis of novel overlapped pattern
design With the use of finite measurements the study
depicted that this decreased measurements was found ENR of
25 dB to obtain the similar PEEFor the appropriate channel
with quickly altering channel information the price might be
acceptable for improving the speed of estimation The study
also proposed a robust channel estimation algorithm where
the additional calculations are carried out when expecting
more estimation error The study depicted that the channel
could be measured more effectively resulting in noteworthy
gains upto 6 dB when comparing with the existing algorithm
(Ali et al 2016) described the variations in the principles of
downlink and uplink NOMA transmissions in a wireless
system The study formulated a maximization issue in a cell
like the user clustering and power allocations Because of the
integral nature of the formulated programming issue the study
solved the issue in to steps which are grouping of users into
clusters and then to optimize the corresponding power
allocations The study proposed a sub optimal scheme that
exploited the gain variations in NOMA groups and clusters into
multiple and single clusters for enhancing the sum-throughput
The results compared the efficiency of OMA and NOMA in
different network scenarios (Lv et al 2017) investigated a
MCR-NOMA where the multicast user functions as relays to
enhance the efficiency of both secondary and primary
networks On the basis of the available CSI three various
secondary user schedule techniques for processing MCR-
NOMA were depicted For evaluating the system efficiency the
study derived the closed form of expressions of OP and order
of diversity for both the networks It has been described that
more spatial temporal diversity could be obtained by using the
CSI for scheduling of the secondary user (Liu et al 2016)
considered a MIMO ndashNOMA scenario for investigating a
dynamic clustering issue in an logical perspective To resolve
the problem of optimization issue three algorithms named top
down A and B bottom up were suggested for realizing various
complexity tradeoff and worst user throughput The study
noted that the top down B algorithm could obtain a better
tradeoff between throughput and complexity amongst the
applied procedures (Fianu and Davis 2018) investigated
three various rules of allocation and demonstrated the optimal
policy as an available inventory function The study also
provided the country level estimation of requirements that are
not met and the determination of the probability distribution
linked with the total undeserved counties The study have
been done for depicting the policy of allocation with respect to
effectiveness and equity (Hou et al 2018) studied the socio
INTERNATIONAL JOURNAL OF SCIENTIFIC amp TECHNOLOGY RESEARCH VOLUME 9 ISSUE 04 APRIL 2020 ISSN 2277-8616
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graphical impact on the mobile video services and thereby
suggested a CTMDP on the basis of resource allocation
technique by considering social graphs as the constraints
With the use of relative value an optimized policy could be
achieved that aimed at increasing the reward regarding the
average system The simulation depicted that the suggested
CTMDP obtained an increased efficiency against the state of
art methods
3 PROPOSED WORK
Fig 2 Proposed flow depicting the overall mechanism
The proposed(Interference mitigation using POMDP) overall flow
is depicted in the figure 2 After setting up of the base station the
distance between the base station and the user was determined
and if the distance is less than 200 meters it is decided as trusted
users and if it is greater than 200 m it is defined as untrusted
users In case of untrusted users the channel state information is
subjected to POMDP (Partially observable Markov Decision
Process) followed by resource allocation The performance
analysis have been done after the system The work considered
a NOMA oriented cellular setup provided with a base station at
the centre and two users as shown in the figure 2 The adjacent
(near) user possess high level of security clearance that is
required for securing with physical layer from the low
securityuntrusted clearance user (U2) that is located at a faraway
distance from the base station P is defined as the maximum
transmit power level (base station)In this paper it is assumed that
all the network nodes are installed with single antenna and further
all the channels are considered to be identical independently
quasi static with Rayleigh distribution with respect to distribution
119862119873(0 120575 frasl
120596 frasl
) In which 120575 is the distance in-between the BS
and nodes 119880 Here path-loss exponent and path-loss constant is
represented as 120572 and 120596 In addition it is assumed that base
station predicted the user location so that a better CSI is
obtainable at base station that is involved in pairing the users
The base station transmits the superimposed mixture
119909 = radic119905 119904 + radic1 minus 119905 119904
In which 119904 119904 are the unit power signals received by users 119880 and
119880 respectively 119905 is the power
allocation coefficient for the adjacent user
119903 = ℎ 119909 radic119875 + 119899
119903 = ℎ 119909 radic119875 + 119899
where ℎ ℎ - the channel gain linked with the
small-scale fading from the base station to users 119880 and 119880
respectively 119899 and 119899 are the extra white Gaussian noise with
variance and zero mean 1198730 and it is assumed that 120588 = 1198751198730 is
the BS convey signal-to-noise ratio (SNR) In NOMA technique
farther user that possess more power
could decode its own signal by considering the adjacent signal as
a noise without decoding the adjacent user message In the
preceding equation it is assumed that U1 first decode the weak
signal followed by decoding its own signal with SICU2 which is
the untrusted user attempted to decode the near user message
after the decoding of the adjacent user messages after the
process of decoding its own message with SICHence the
following equation have been achieved
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119879119900119905119886119897 = 119878119868119873119877 119878119868119873119877
119878119868119873119877 119878119868119873119877
+
where 119878119868119873119877 represented the signal-to-interference-plus-noise-
ratio of user 119898 that was decoded by 119880 for 119898119899120598119894 2+ and the
channels gain of 119880 denoted by |ℎ |
followed an exponential distribution
with the parameter 120577 = 120596 120575
Problem Formulation
Hence the base station should achieve and serve a better
communication for the users who are susceptible to security
threat from untrusted user the proposed system defined two
kinds of QoS efficiency measures that could be regarded to be
important for framing the issue In specific the study defined a pair
of OP to check the reliability of the QoS satisfaction In general
the pair OP is stated as the probability in which the obtainable
data rates dor the users equal to or greater than the least target
threshold The next metric also called as the SOP is the
probability that the non negative secrecy capacity obtained by the
trusted user is more than the threshold value
The following issue aimed at reducing the pair OP subjected to a
SOP factor for the user U1 that is provided by
min
119875
0 lt 119905 lt 05
119878119874119875 le 120573
in which 119875 119878119874119875 and 120573 are the pair OP SOP(119880 ) and the
permissible SOP threshold
4 PERFORMANCE ANALYSIS
Derivation of the Pair OP
With the use of Shannonrsquos capacity formula and considering
119862 and 119862
as the threshold capacities of users 119880 and
user 119880 respectively the OP of the pair could be provided
by
119875 = 1 minus 119876 119909119876
in which
120591 = 2
119898 120598 119894 2+
120601 =
( )
120601 =
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119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 1 120601 gt 120601
For having 120601 gt 120601 the constraint on
the power allocation factor (t) needs to be satisfied
(119905 gt
) and for this case 119876 could be obtained as
follows
119876 = exp (
)
lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 2 120601 lt 120601
Like case 1 it was stated that opposite constraint on
a as (119905 lt
) and
119876 can be derived as follows
119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
The OP of the NOMA pair
119875 = 1 minus 119891(119905)119896 (119905)
lt 119905 lt
1 minus 119891(119905)119896 (119905) 0 lt 119905 lt
in which
119891(119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
Derivation of SOP of 119880
With Shannonrsquos capacity formula the secrecy rate of
user 119880 was provided by
119878119862 = 119869 minus 119869
119869 = log (1 + 119879119900119905119886119897 (r (1)))
119869 = log (1 + 119879119900119905119886119897 (r (2)))
119878119862 is the non-negative secrecy capacity of 119880 Provided the
secrecy capacity in the SOP of 119880 is
119878119874119875 = 1 minus 120584119890
119860 =
120584 =
119879 - the user 119880 secrecy target rate
Theorem 1
Outage-optimal power allocation factor
119905 = radic
( )
In which 119908 =
119908 =
119911 = 1 + 120591
The minimum power allocation factor (119886 )
119905 =
(
)
The optimal OP of the NOMA pair under the SOP constraint
=
( )
( ( ))119890
( )
That is lt 0whih meant that the U1 (SOP) is a reducing function
Of t that results in the optimal power allocation factor that is
greater than 119905 for the satisfaction of secrecy constraining
factorPartially observable Markov decision process S is
represented as statesLet D is the channel features which is
consider here as actions the conditional transition probability
between states is regarded as T Reward function R is
calculated as the prediction of maximum capacity channel with
respect to data rate r = R(S x D) the agent receives an
observation o ϵ 120118 o isin Ω display style oin Omega that
depended on the new environment state S and on the just
took action d with the probability O(o|s d)
Reward received at time t is conveyed as r = R(S x D)
H is the belief states over POMDP states
119867 is the belief state transition function
119903 = 119877(119867 x 119863) is the reward function on the belief states
119861 (ℎ 119889 ℎ ) = sum Pr ( 120118 ℎ |ℎ 119889 119900) Pr(119900|119889 ℎ)
Pr(h |h d o) =
1 if the belief update with arguments h d o returns h 0 otherwise
The reward function is updated on the basis of the belief MDP
r (h d) = sum h(s) R(s d) isin
the agent focus on the largest expected immediate rewardin
other words the maximum capacity channel The section
analyse the accuracy of the analytical derivations under
various settings
Figure 3 The feasible pairing
The SOP of U1 with the increasing untrusted user U2 and
distance (d2) for several BS transmits Signal to Noise Ratio
at 120588 = minus20minus1020 119889119861is depicted in with a=005 and 01 and
d1=200m is depicted in the figure The results stated that the
U1(SOP) is a gradually reducing function as per d2 that
implies that the increasing value of d2 leads to the
improvement of the SOP of U1 Since the provided constant
threshold ϵ in SOP restraint U2must be situated at a larger
space when compared with threshold value to obtain the SOP
of U1 Apart from that it is normal that the high the target
secrecy rate rises the SOP of U1
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Figure 4 The Secrecy outage probability
Feasible Pairing in th SOP of pair OP and U1 with the
enhanced power allocation factor (a) in which d2 = 700 m d1
= 200 m 120588 = 15 dB and ϵ = 01 The results depicted that the
the pair OP and SOP of user U1 with increased a for two (d2)
various distances of the (U2) untrusted user The results
approve the convex nature of the pair OP and the SOP curve
is gradually decreasing on the basis of a Generally during the
increase in a the power assigned to the weak user message
decreases that minimize the ability of U2 for discriminating the
superior positioned signals thereby improving the SOP of U1
Figure 5 The Pair outage probability
Pair OP in case of rising U2 untrusted user in distance (d2)
for different base station transfer the signal to noise ratio(120588 =
5 15 25 dB) where a = 015 and d1 = 200 m
Figure 6The infeasible pairing of secrecy outage
probability of the pair OP and U1
The infeasible pairing of SOP (U1) and the pair outage
probability with the enhanced allocation of the power ad1(200
m)d2(300 m)120588 = 15dB and ϵ = 0
The figure 6 depicted that the
The figure 6 shows the similar plotting of the data by altering
the untrusted user location by transferring it to a BS closer
distance (d2 = 300 m) It also depicted that the U1 SOP
constraint of is disrupted at a because the SOP is more than ϵ
The accuracy is well-matched and verified with all range of
numerical simulation The results noticed that the efficiency is
based on the comparative locations of the two user with the
base station
Figure 7 The figure 7 depicts that SNR versus strictly
positive secrecy rate
The observed graph proves that the secrecy capacity
outperforms the existing techniques The proposed precoding
application increases the performance of the system The
transmission power of the system is the power required to
transmit a particular data When there is an increase in the
number of users there is the possibility of inference in the data
transmission and hence the efficiency of the data rate may be
affected Depending on these instances the efficiency of the
antenna capacity to withheld and accommodate the data
determined
Figure 8 The power radiated by BS antenna
In the figure 8with respect to the simulation setup the
precoding methods are performed based on the radiated
power per BS antenna is depicted The results observed the
better efficiency of the proposed system The proposed proves
to be better when compared with existing linear precoding
methods in the prescribed three metrics thereby stating that
MRT may be utilized for the the examination of the secrecy
capacity Our proposed technique spends less radiatated
power thereby increasing the overall capacity of the system
5 CONCLUSION The NOMA system decodes the messages of other user pairs
on the similar resources thereby promoting user possibility
The technique interprests a security threat in which the BS
serves the untrusted users The study analysed the SOP and
OP in both multi user and two user NOMA system in which the
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base station pairs the trusted user in closed type of
expressions The proposed (Interference mitigation using
POMDP) also enable the understanding of possibility of
achieving outage optimal efficiency to pair under SOP
constraints The numerical verifications verified the efficiency
of the analytical derivations
6 REFERENCES [1] ALI M S TABASSUM H amp HOSSAIN E 2016
Dynamic user clustering and power allocation for
uplink and downlink non-orthogonal multiple access
(NOMA) systems IEEE access 4 6325-6343
[2] ARAFA A SHIN W VAEZI M amp POOR H V
2019a Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
15 210-222
[3] ARAFA A SHIN W VAEZI M amp POOR H V
2019b Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
[4] CAO K WANG B DING H LI T amp GONG F
2019 Optimal Relay Selection for Secure NOMA
Systems under Untrusted Users IEEE Transactions
on Vehicular Technology
[5] DANG S CHEN G amp COON J P 2018
Multicarrier relay selection for full-duplex relay-
assisted OFDM D2D systems IEEE Transactions on
Vehicular Technology 67 7204-7218
[6] DANG S COON J P amp CHEN G 2017 Outage
performance of two-hop OFDM systems with
spatially random decode-and-forward relays IEEE
Access 5 27514-27524
[7] FIANU S amp DAVIS L B 2018 A Markov decision
process model for equitable distribution of supplies
under uncertainty European Journal of Operational
Research 264 1101-1115
[8] FURQAN H M HAMAMREH J amp ARSLAN H
2019 Physical Layer Security for NOMA
Requirements Merits Challenges and
Recommendations arXiv preprint arXiv190505064
[9] HOU L ZHENG K CHATZIMISIOS P amp FENG Y
2018 A Continuous-Time Markov decision process-
based resource allocation scheme in vehicular cloud
for mobile video services Computer
Communications 118 140-147
[10] KOKSHOORN M CHEN H WANG P LI Y amp
VUCETIC B 2016 Millimeter wave MIMO channel
estimation using overlapped beam patterns and rate
adaptation IEEE Transactions on Signal Processing
65 601-616
[11] LIU Y ELKASHLAN M DING Z amp
KARAGIANNIDIS G K 2016 Fairness of user
clustering in MIMO non-orthogonal multiple access
systems IEEE Communications Letters 20 1465-
1468
[12] LV L CHEN J NI Q amp DING Z 2017 Design of
cooperative non-orthogonal multicast cognitive
multiple access for 5G systems User scheduling and
performance analysis IEEE Transactions on
Communications 65 2641-2656
[13] SUN Y NG D W K ZHU J amp SCHOBER R
2018 Robust and secure resource allocation for full-
duplex MISO multicarrier NOMA systems IEEE
Transactions on Communications 66 4119-4137
[14] ZHANG H YANG N LONG K PAN M
KARAGIANNIDIS G K amp LEUNG V C 2018
Secure communications in NOMA system
Subcarrier assignment and power allocation IEEE
Journal on Selected Areas in Communications 36
1441-1452
[15] ZHAO T LI G ZHANG G amp ZHANG C-X
Security-Enhanced User Pairing for MISO-NOMA
Downlink Transmission 2018 IEEE Global
Communications Conference (GLOBECOM) 2018
IEEE 1-6
PhD THESIS Non-Exclusive License to
GUJARAT TECHNOLOGICAL UNIVERSITY
In consideration of being a PhD Research Scholar at GTU and in the interests of the
facilitation of research at GTU and elsewhere I Pankaj Manubhai Patel has Enrollment
No139997111012 hereby grants a non-exclusive royalty-free and perpetual license to
GTU on the following terms
a) GTU is permitted to archive reproduce and distribute my thesis in whole or in part
andor my abstract in whole or in part (referred to collectively as the ldquoWorkrdquo) anywhere
in the world for non-commercial purposes in all forms of media
b) GTU is permitted to authorize sub-lease sub-contract or procure any of the acts
mentioned in paragraph (a)
c) GTU is authorized to submit the Work at any National International Library under
the authority of their ldquoThesis Non-Exclusive Licenserdquo
d) The Universal Copyright Notice (copy) shall appear on all copies made under the authority
of this license e) I undertake to submit my thesis through my University to any Library
and Archives Any abstract submitted with the thesis will be considered to form part of
the thesis
f) I represent that my thesis is my original work does not infringe any rights of others
including privacy rights and that I have the right to make the grant conferred by this
nonexclusive license
g) If third party copyrighted material was included in my thesis for which under the terms
of the Copyright Act written permission from the copyright owners is required I have
obtained such permission from the copyright owners to do the acts mentioned in paragraph
(a) above for the full term of copyright protection
h) I retain copyright ownership and moral rights in my thesis and may deal with the
copyright in my thesis in any way consistent with the rights granted by me to my
university in this non-exclusive license
i) I further promise to inform any person to whom I may hereafter assign or license my
copyright in my thesis of the rights granted by me to my university in this non-exclusive
license
j) I am aware of and agree to accept the conditions and regulations of a PhD including
all policy matters related to authorship and plagiarism
Signature of the Research Scholar
Name of Research Scholar Pankaj Manubhai Patel Date 17092021
Place Ahmedabad
Signature of Supervisor
Name of Supervisor Dr Chetan B Bhatt Date 17092021
Place Ahmedabad
Seal
i
ABSTRACT
The landscape of future fifth-generation (5G) radio access networks is
expected to seamlessly and ubiquitously connect everything and
support higher traffic volumes densely connected wireless devices and
diversified requirements on reliability latency battery lifetime etc as
opposed to the current fourth-generation (4G) cellular networks
Moreover in unexpected or emergencies (such as disaster relief and
service recovery) the deployment of terrestrial infrastructures is
economically infeasible and challenging due to high operational
expenditure as well as sophisticated and volatile environments To
address such novel issues intelligent heterogeneous architecture by
leveraging unmanned aerial vehicles (UAVs) (or commonly known as
drones) has been considered to be a promising new paradigm To
improve the system performance of UAV communication in 5G
networks physical layer techniques are of much concern as they affect
the applications of UAVs significantly In this research work security
aspects of NOMA-based UAV communication network have been
considered for optimization as physical layer security in a wireless
communication network is not as robust as wired communication due to
fading and varying SNR scenarios Here primarily two usersrsquo models
as the trusted and untrusted user communicating with BS have been
optimized for outage-optimal performance considering pair Outage
probability and Secrecy outage probability as performance metrics The
achieved results are extended to multi-user scenarios also and for the
optimal policymaking dynamic programming and Partially Observable
Markov Decision Process (POMDP) optimization approaches have
ii
been simulated and verified The simulated results have shown that
POMDP has potential consideration as a resource scheduling
optimization technique in the NOMA-UAV communication network for
providing secure and more robust performance
iii
Acknowledgment
Completing a PhD is a tough task that requires hard work and a lot of effort This is
often an overwhelming but also great experience that I would not have been able to
complete without the assistance and support of so many people Thus it is my great
pleasure to thank all those people First of all I would like to thank almighty for giving
me the strength to carry out this task I would like to deeply thank Dr Chetan B Bhatt
my supervisor for his guidance encouragement and support over these years This
research work would not have been possible without his constructive pieces of advice his
systematic guidance and his patient support thought out the duration of my research work
I would like to express my sincere gratitude to Dr Harshal A ALOORKAR and Dr
KIRAN R TRIVEDI Dr Mehul Raval my doctoral progress committee members Their
rigorous style of reviewing and constructive feedback with valuable suggestions of Dr
Prakash Gajjar Mr Hitesh Panchal and Mrs Monali Mandli who spent their valuable
time whenever required for discussing aspects of this work and provided relevant material
as well Mr Parth Modi and Mr Jagadish Patankar to initiate and inspired me a lot to
continue my work Mr Mukesh Sharma who help in maintain documents I am also
thankful to my parents and family members who always stood with me in each critical
situation and supported me endlessly I am thankful to all EC departments of various
polytechnic and degree engineer colleges for their cooperation in every possible means
Lastly I would thank all the people who directly or indirectly helped me during this very
important phase of my life
Pankaj Manubhai Patel
vi
List of Abbreviation
3GPP 3rd Generation Partnership Project
5G Fifth Generation
A2G Air to Ground
AWGN Additive White Gaussian Noise
BDM Bit Division Multiplexing
BS Base Station
BPCU Bits Per Channel Use
CDMA Code Division Multiple Access
CR Cognitive Radio
CSI Channel State Information
CNPC Control and Non-Payload Communications
CRN Cognitive Radio Networks
D2D Device-to-Device
DCP Difference of Concave Programing
DOMP Dynamic Optimization Method of Programming
FR Floating Relay
GSM Global System for Mobile Communications
HLPSL High-Level Protocol Specification Language
ICT Information and Communication Technology
IoT Internet of Things
IRS Intelligent Reflecting Surface
IMT Information Management Technology
vi
LDS Low-Density Spreading
LTE Long Term Evolution
LTE-A Long Term Evolution Advance
MCR Multicast Cognitive Radio
MI Mobile Internet
MIMO Massive Multiple-Input Multiple-Output
mm-Wave millimeter Wave
MTC Machine-Type Communication
MUSA Multi-User Mutual Access
NOMA Non-Orthogonal Multiple Access
OFDMA Orthogonal Frequency Division Multiple Access
OMA Orthogonal Multiple Access
OP Outage Probability
POMDP Partially Observable Markov Decision Process
PLS Physical Layer Security
PDMA Pattern Division Multiplexing Control
PUN Primary User Networks
QoS Quality of Service
RIS Reconfigurable Intelligent Surface
RNRF Random Near-Random Far
Rs Target Secrecy Rate
SAGIN Space-Air-Ground Integrated Networks
SIC Successive Interference Cancellation
STBC Space-Time Block Coding
vi
SBF Secrecy Beam Forming
SCMA Sparse Code Multiple Access
SOP Secrecy Outage Probability
TAS Transmit Antenna Selection
TDMA Time Division Multiple Access
UAVC Unmanned Aerial Vehicle Communication
UMTS Universal Mobile Telecommunication Systems
URLLC Ultra-Reliable Low Latency Communication
vii
List of Figures
Figure Title Page
No
11 Usage of wireless sensor network and UAV in the
hazardous disaster control
6
12 UAV network applications types with security services
architecture
8
13 UAV-assisted heterogeneous network architecture 12
14 Security problems in the UAV 15
15 Comparative analysis of NOMA vrsquos OMA 18
21 Vehicular communication NOMA system 28
22 RS-NOMA against an external eavesdropper 31
31 Downlink NOMA network 44
32 Uplink NOMA network 46
33 Multi-two user architecture of NOMA system 49
34 Flow Diagram of the proposed system 50
35 Near and Far User 51
41 Impact on Sop with increase distance between BS and user U2 60
42 Impact on Sop with increase distance between BS and user U2 61
43 Feasible pairing t Vs pair OP 61
44 Infeasible pairing t Vs pair OP 62
45 Secrecy outage probability 63
46 Pair outage probability 63
47 SNR versus Strictly positive secrecy rate 64
48 Power radiated by per MMBs antenna 64
viii
List of Tables
Table Title Page
No
11 Physical layer hazards and measures in UAV wireless
communication network
13
21 Comparative analysis 33
31 List of parameters59 54
41 Simulation parameters 59
ix
Table of Content
Sr
No
Title Page
No
I Abstract I
II Acknowledgment II
III List of Abbreviation III
IV List of Figures Iv
V List of tables V
1 Introduction 1
11 Modern technology and its needs 1
111 Long term evolution of 4G network 2
112 Migration from 4G LTE to 5G for UAV communication 3
12 UAV assisted communication in heterogenous sensor network 5
121 Introduction to UAV Communication network 7
122 Tyews of UAVs 8
1221 UAVs as flying BSs 8
1222 UAVs as aerial UBs 10
13 Unmanned aerial vehicle for 5G network 11
14 Physical layer insecurity in UAV communication network 12
141 Principles of security 13
15 Non-Orthogonal Multiple Access (NOMA) system secured
communication
16
151 Comparison of NOMA Vs OMA 16
1511 Spectral throughput and efficiency 17
1512 User fairness and higher lately 17
1513 Compatibility 17
16 Problem identification 18
17 Motivation 19
18 Aim and objective of the research 20
19 Thesis organization 21
2 Literature review 23
x
21 Integration of UAV Networks for 5G and B5G communication 23
22 UAV-NOMA in physical layer security enhancement 26
23 Research methodology 38
24 Summary 39
3 System model for NOMA-UAV communication 41
31 NOMA -UAV system secured communication for 5G 41
311 The basic scheme of NOMA 41
312 Downlink of NOMA 44
313 Uplink of NOMA 46
314 Comparison of NOMA and OMA 47
32 PLS performance metrics in NOMA -UAV communication 47
321 SOP and OP - two user and multi-user NOMA system 48
322 System Model 48
323 Partially Observable Markov Decision Process-POMDP 50
324 Problem formulation 52
33 Performance Analysis Improving PLS Insecurity of NOMA
System
53
331 The pair OP calculation 53
332 Pseudo-code for the proposed algorithm 55
34 Summary 57
4 Result and discussion 58
41 Performance measure of secured NOMA-UAV communication
model
58
42 Numerical result and discussion 59
421 Feasible amp Infeasible pairing of trusted amp untrusted
users
60
422 The secrecy outage probability and pair outage
probability
62
423 SNR versus strictly positive secrecy rate 63
424 Power radiated by per MMBs antenna
64
43 Conclusion and scope of future work 65
431 Conclusion 65
432 Future scope 66
xi
5 References 67
8
Publications 78
1
CHAPTER -1
INTRODUCTION
11 Modern technology and its needs
Mobile technology has undergone various generational shifts transforming the
cellular framework into a worldwide set of interconnected networks In recent days
the fifth generation (5G) has delivered voice as well as video streaming It has a
very complex range of networking services for more than nine billion users and also
billions of devices that will be connected (Hu 2016) However 5G offers a new
outlet for reflection It involves a radial network architecture for the installation of
communication-type machines 5G network can also include powerful support
applications with widely varying operating parameters 5G is a blend of network
technologies that have been developed The new 5G technology will be able to
exchange information anywhere every time for the benefit of people enterprise
and society and technical environments using a restricted access bandwidth to
carry data Now it is more than a modern series of technologies and as opposed to
previous generations would entail tremendous infrastructure or machinery
upgrades This technology aims to expand on the advances that telecommunications
systems have already achieved The projected standards of efficiency that
technologies would need to resolve are
bull Five times reduce end-end latency
bull Ten to a hundred times the higher complex rate of user data
bull Battery life is ten times longer
bull 10 to 100 times higher number of connected devices
In this research work the UAV-assisted communication over the 5G network has
been proposed with enhanced physical layer security aspects NOMA has been
proposed as the reference framework architecture for UAV communication as one
of the recent popular 5G techniques Along with the advantage of suitability in UAV
communication network NOMA has the disadvantage of insecurity in the physical
layer Here the migration of Long Term Evolution (LTE) to advanced physical layer
2
security for Unmanned Aerial Vehicle communication (UAV) over 5G network has
been proposed and also improve the insecurity of Non-Orthogonal Multiple Access
(NOMA) System We will discuss in the further chapter the proposed work This
chapter describes the introduction and basic concepts of the 5G networks with
methodology techniques and types It states the problem identification motivation
and further aim and objective of this work
111 Long Term Evolution of 4G Network
LTE is customary for 4G wireless broadband trends that provide improved network
capability and gives mobile device users speed It offers high peak data transform
rates in the range of 100 Mbps and 30 Mbps downstream and upstream
respectively It provides a capacity of scalable bandwidth mitigated latency and
backward compatibility with the previous Global System for Mobile
Communications (GSM) and Universal Mobile Telecommunication Systems
(UMTS) technology
The fourth development of cellular networks (4G) has already been developed to
meet the standards of the 3G and 2G families Every 10th year a new mobile
generation claimed to be familiarized with the first 1G system in 1981 tracked by
the 2G system that went on to roll out in 1992 and 3G launched in 2001 growth in
the year 2002 of 4G networks The actual new revolution began in December 1998
with the 3rd Generation Partnership Project (3GPP) With high-quality video and
images 3G networks are designed for multimedia networking with them Peoples
communication can also be enhanced and connectivity to public and private
network information and resources has improved with higher frequencies and new
flexible communication features third-party device applications
With the start of LTE-Advanced several vital demands and improvements are
beginning to emerge Various importance purposed for LTE-Advanced can be
exemplified as follows (Abed)
bull Provides spectrum output with LTE delivered more than three times
bull Spectrum can help scalable bandwidth and convergence of the spectrum
where it is necessary to use a non-contiguous range
3
bull Provides uplink and downlink spectrum output that varies between
15bpsHz and 30bpsHz
bull The edge throughput must be twice that of the user cell in LTE
bull From idle status to connected status the communication latency scenario is
smaller than 50msec and less than 5msec for direct packet transfer
bull Any users total throughput must be three times that of LTE
bull LTE advancement will provide 3GPP as well as LTE compatibility via inter
networking
bull The mobility conditions that are used in LTE are identical
The latest LTE advanced requirements are not yet included in device
specifications there are high-level purposes Before it is fixed in the specifications
and needs to be tested much effort remains to be approved
112 Migration from 4G LTE to 5G for UAV communication
The productive implementation of a UAV communication network in 4G and the
upcoming wireless network is included in identifying combined solutions to test
the correlation with both multitudes and also energy-efficient transmission Then
the process of the UAV-BS to optimize coverage and power It is stated that the
energy efficiency of the UAV-aided communication system is needed Efficient
energy utilization contributes to increased air time in the contact system and
increased joulesbits at a provided energy level Also aerial cell coverage and
ability may be because of various parameters such as antenna gains transmission
strength radio access technology UAV altitude and deployment environment
4G is the fourth generation of network infrastructure technologies to replace 3G and
in addition to the popular 3G4G methods Code Division Multiple Access
(CDMA) Time Division Multiple Access (TDMA) and Orthogonal Frequency
Division Multiple Access (OFDMA) Researchers are designing the latest Non-
Orthogonal Multiple Access (NOMA) technologies to be used because of their
capability to improve the performance of communication networks Non-
4
orthogonality-based device designs have recently been developed for use in
communication networks and drawn considerable interest from researchers
Henceforth Multiple Access (MA) methods can be sub-divided as OMA and
NOMA Each user may utilize orthogonal communication resources to determine
multiple access interference inside a frequency band code and time slot in OMA
Its methods such as First generation (1G)- FDMA 2G -TDMA 3G -CDMA and
4G - OFDMA have been used in previous network generations In NOMA by
producing a higher spectral efficiency however enabling some amount of multiple
entree intrusion in receivers and multiple users may use non-orthogonal resources
simultaneously Recently the credibility of NOMA as a solution to the problems of
the next generation of wireless networks has been increased Compared with OMA
technologies NOMA has been described to improve spectral quality be well-
adjusted with air connectivity and can provide accommodations for multiple
strategies at the same time of frequency Therefore enabling excellent progress to
massively correlated devices
In particular NOMA also affects mitigating interference by using OFDMA as an
orthogonal method or through offering a standard intra-cluster access beam across
multiple users and inter-cluster access in NOMA Recent studies have concentrated
primarily on the provision of Air to Ground (A2G) connectivity services through
optimization of a different point of view
The output of the UAV-based communication network was discussed in the Device
to Device (D2D) implementation setup The proposed system hypothesized
interference caused through D2D network nodes deprived of acknowledging the
occurrence of global BS Also several studies addressed the efficiency of NOMA
It permitted the deployment of fixed-wing to assist coverage in-ground user located
outer location of offloaded BS
NOMA systems are divided into two categories namely code domain and power
domain multiplexing In the power domain user accounts are allocated to different
power coefficients as per their channel complaint to reach optimal device
efficiency Multiple user signals are applied to the side of the sender Then on the
received signal Successive Interference Cancellation (SIC) is implemented to
decipher signals in sequential order until the predicted signal is achieved offering
5
a good trade-off between efficiency of the system and user fairness Different code
domain multiplexing is Sparse Code Multiple Access (SCMA) Low-Density
Spreading (LDS) and Multi-User Mutual Access (MUSA) Compared to power and
code domain multiplexing there are alternate NOMA techniques such as Bit
Division Multiplexing (BDM) and Pattern Division Multiplexing Control (PDMA)
However this multiplexing is capable of improving the efficacy of spectral It
requires a large transfer of bandwidth which is not appropriate for new methods
But on the other side the power domain has direct execution since there is no need
for significant improvements to the current networks It also does not necessitate
bandwidth to increase spectral efficiency In this chapter the main emphasis
depends on the power domain NOMA While OMA strategies can produce the best
results also with necessary receivers due to no mutual intervention among users in
an optimal situation they cannot even resolve increasing problems due to growing
demands on connectivity growth and even beyond
12 UAV assisted communication in heterogeneous sensor network
Wireless communications had created a golden chance for urban and rural
territories The LTE (Long term evolution) and LTE-A (Long term evolution
Advance) had offered the service (with QoS) for all customers through wireless
The traffic properties in the machine type communications (MTC) and the
accumulation of the MI (Mobile Internet) had made the difficulty of implementing
the cellular communication networks Installing base stations was impractical in the
urban areas due to its cost To overcome this issue the UAV suggested that it
contains the merits of compatibility and high battery life and is affordable Most of
the devices like the sensor nodes and professional cameras had been used in UAV-
assisted networks Here the UAV-assisted floating relay (FR) was launched in the
cellular communication networks UAVs were implemented more with WSN
(wireless sensor networks) The base stations were adopted with the UAV So the
MI and MTC traffic challenges were controlled (Yue Li amp Cai 2017)
UAV-assisted Heterogeneous networks had implemented in vast practical
applications UAV helped heterogeneous networks were applied in the military
department In the military the UAV had examined and surveyed the opposing
6
countryrsquos activities for security The UAV-based heterogeneous networks were
used in the military sectors where a novel authentication scheme was introduced
As The one-to-one communication via WSN was considered as secured
communication WSN had the disadvantage of consuming power The
authentication was implemented in the tool of Automated Validation
of Internet Security Protocols and Applications (AVISPA) in which the expression
had been written in the High-Level Protocol Specification Language (HLPSL)
programming language The authentication had evaluated between the user and the
base station Similarly the authentication between the user and the UAV was
calibrated The citizen and economic safety are predicted and conserved through
reliable communication in the military by obtaining foes exploration information
The faithful secured communication was confirmed using AVISPA (Rashid et al
2019)
Figure 11 Usage of wireless sensor network and UAV in the hazardous
disaster control
The integration of the wireless sensor networks and the unmanned aerial vehicle
UAV was analyzed and applied to manage the natural disaster illustrated in Figure
11 The aircraft can prevent the fire spreading drop sensors the temperature map
and biodiversity map by sensors the wildfire can easily route The wild animals can
7
be tracked and the dynamic data of moving animals can be gathered by WSNs The
biologists can fix the sensor in the animals collar the radiation that positively
affects humans can be observed in affected areas The WSNs help to prevent heart
attack of a person by monitoring heart rate The state of health can be known
through a message alarm using a GPRS system
The cooperative networks of WSN and UAV were implemented in the military
sector for the advantageous feature The UAV was providing good connections
overlapping and overall data rate The conventional UAV method aided sensor
networks concentrated only on the single tasks of monitoring accumulating
information and localization The multi-UAV had not been implemented in the
sensor networks The animal colony perception technique was utilized for
scheduling the resourced and the target assignment Functions of multi-data were
used for localization by the target recognition method (Gu Su et al 2018)
The Physical Layer Security (PLS) was achieved through 5G technologies delicate
coding for the PLS dense MIMO multi-input multi-output mm-Wave frequency
band using heterogeneous sensor networks NOMA and full-duplex mode of
communication IoT and Machine-type communications (MTC) emerged in the 5G
systems (Wu et al 2018)
121 Introduction to UAV communication network
The usage of the UAV will develop more in the next era These pre-programmed
aircraft are intended for applications in several civil settings as well as industrial
visualization agriculture rescue and search and then receiving of scientific data
These devices are called the unsuccessful inaccuracy of drones which must be
incorporated into the system of national airspace as well as worldwide The usage
of UAVs in the neutral form is always secure It has a direct inference for the control
and a payload communication system that is utilized to function effectively
Similarly surveillance and navigation operations must be made more accurate and
consistent Due to these critical factors many kinds of research in a UAV testing
development and standardization difficulties are undergone through industries
education and governments
8
Even though civil aircraft had been operating for many years yet UAV offers new
consequences in terms of various flight profiles For example high dynamic
maneuvers and low elevation flights need bandwidth video and different ground
site characteristics namely clutter locations and elevation antennas which are low
This chapter explains the core topic of the proposed work The migration of LTE
4G towards the advanced one of the physical layers for UAV communication It has
higher mobility and lower expense identified in a broad range of applications
122 Types of UAVs
The UAVs have a two-network application with security services such as UAVs as
Flying Base Stations (BSs) and UAVs as Aerial BSs in the presence of
eavesdroppers
(a) UAVs as Flying BSs (b) UAVs as Aerial mobile UEs
Figure 12 UAV network applications types with security services
architecture
1221 UAVs as flying BSs
The required infrastructure can be destroyed in natural disasters particularly
tsunamis earthquakes and snowstorms and the requisite emergency data traffic
cause both overloading and congestion of neighboring mm-Wave (Zeng et al
2016) A capable explanation is to rapidly introduce low-altitude UAVs as flying
9
BSs in such a network breakdown to improve the communication infrastructure to
mitigate cell congestion or site failure thus creating a small aerial cell
In this situation wireless communications can occur in an ad-hoc manner with
UAVs to UEs UAVs to UAVs As highlighted in Figure-12 (a) and control
stations of UAVs to ground It will increase capability dramatically and enlarge the
target of wireless networks in provisional measures as it is possible to create LoS
communication links among UAVs and UEs supported on the ground Yet form an
operating aerial cell system to monitor ground segments of UEs mobility which is
more stable to minimize sporadic connectivity on the other side
Also this can be expanded to allow several UAVs-BSs to be deployed to increase
the exposure area for supporting a wide range of UEs A network period various
UAVs-BSs is entirely independent A new paradigm was introduced through
collaboration between UAVs-BSs to extend the feasibility for a single UAV from
either a stand-alone active sensor to a wireless network over the next generation
There is a growing concern about the privacy problem in tandem with the brief
introduction of this network Wireless protection is the central issue of the
communication level wherever eavesdropping subsidizes for deliberately listening
to a source of secret information which harms the extensive placement of UAV-
BSs
A UAV-BSs is to mount several antennas in the UAV-BSs the benefits of multi-
antenna innovations geographical degree of freedom that offers an ability for UAV-
BSs to transmit eavesdropping airborne beams
Notice that in UAV systems multi-antenna technology can be technically applied
while directly modifying the separation of the antennas The existing system has
shown that transmitted beam forming models can significantly boost the
confidentiality efficiency of wiretap channels for multiple antenna transmitters
Noise may be inserted with the signal to substantially degrade the acknowledged
SINR at the eavesdroppers to prevent the information overflow
10
1222 UAVs as aerial UEs
This has already been demonstrated by reaping the benefits of Wi-Fi and LTE
technologies through field trials (Van der Bergh et al 2016) UAV-UEs typically
get their tasks for a variety of convincing IoT applications mainly in air freight
services like the google wing project Unlike conventional land base package
delivery but UAV delivery has distinctive merits such as
bull Acceleration of land transport as UAVs are not liable to road jams
bull Connection to areas that are difficult to reach
bull Decreasing the use of capital about workforce and electricity
UAV distribution is significantly dependent on having reliable and secure wireless
communication among UAVs and ground BSs especially if the UAV needs control
outside LoS the UAV-UEs are used which can develop LoS connectivity to cellular
BSs The UAV-UEs on the one hand provides high-speed access to data as it can
fly continuously in either direction On the other hand the installation of UAV-UEs
can lead to significant interference with the ground BSs in the execution of their
missions
A wide-scale installation of UAV-UEs is only feasible for this reason if the issues
of interference management are tackled It is widely known that interference
negatively affects wireless networks As highlighted in Figure-12 (b) indeed aerial
and ground UEs are served through a cellular network with a possible eavesdropper
that tries to intercept the message intended for permissible basic UEs
A cost-effective approach is to be used for coordination among ground BS and
UAVs to enhance secure transmission which is part of the UAVs acting as friendly
transmitters to degrade the wiretapping channels efficiency and thus enhance
secrecy efficiency A UAV acting as a mobile jammer can dramatically and
dynamically change its position as near as possible to the earth eavesdropper and
distribute them by sending the radio signals whereas strong LOS connection
characteristics are a beneficial feature with less earthly fading and shadowing
impairment
11
13 Unmanned Aerial Vehicle for 5G Networks
UAVs have technologically advanced as a revolutionary movement in delivering
pervasive connectivity from either the platforms of the sky as aerial
communication particularly for temporary User Equipment (UEs) (B Li et al
2019) Due to fully controllable UAV flexibility through miniaturization as well as
continuous cost reduction low-altitude UAVs are rapid and flexible designed for
operation and reconfiguration They are probable to have higher Line-of-Sight
(LoS) ties to ground UEs
A broad range of applications like inspection of infrastructure precision farming
and disaster area monitoring is becoming accessible in this aspect Moreover
further projects have also been set up to employ aerial platforms for broadband
access to distant elements such as the Google Loon and the Facebook Drone Project
to mention Highly populated UEs are desperate for broadband wireless
communications with the coming 5G period and network providers are supposed
to maintain numerous networks with high demands for wireless data like
multimedia streaming and also video downloads The relentless growth in the
amount of traffic of mobile networks puts a burden on operators in the form of
higher capital and operational expenditure Deploying small cell networks is an
intuitive alternative to outsource cellular traffic
Although in unforeseen or temporary events as mobile environments are
complicated volatile and heterogeneous the implementation of terrestrial
infrastructures is difficult The accessibility of aerial access points to enable
extensive complex connections is one possible solution However in unforeseen or
temporary events as mobile environments are complicated volatile and
heterogeneous the implementation of terrestrial infrastructures is difficult The
accessibility of aerial access points to enable extensive complex connections is one
possible solution UAV communication performance benefits from the simplicity
of the compact transceiver and progressive control methods that obtain broad
exposure and set up internet networks
12
Figure 13 UAV-assisted heterogeneous network architecture
The above Figure 13 is depicted to build flexibility of the network with enhanced
ability and elasticity It is a good network that offers security endowment This is
due to the transmitting information to UAV communication which is tapped
through ground unauthorized user and is known as an eavesdropper
Here through eavesdropper based on the upper layer cryptographic techniques
wireless communication in contradiction of unauthorized access has been protected
However it is very tough to achieve because of key management as well as more
computational difficulties in developing network architecture PLS affects the
characteristics of intrinsic wireless networks as a fascinating preparation such as
interference noise fading loss collecting signal characteristics in malicious
eavesdroppers and techniques of signal processing
14 Physical Layer Insecurity in UAV communication network
Jamming is either a well-defined WSN attack on a physical layer It disrupts the
radio waves being used by nodes of the network The attacker successively
expresses the denial of the simple MAC protocol over the wireless network The
impressive network can be disrupted at which a single frequency is being used
13
throughout a network (Modares et al 2011) In addition jamming can increase
energy consumption in the node by inserting impudent packets The receiver nodes
will also generate resources when receiving the packets In (Jeon 2006) four
different terms of jamming attacks that an intruder could use to interrupt the
wireless network activity Tampering is yet another physical layer assault
Table 11 Physical layer hazards and measures in UAV wireless
communication network
(Kumar et al 2014)
Hazard Security measures
Jamming Channel blacklisting and hopping
Interference Channel hopping and blacklisting
Tampering Security and key modification
Sybil Physical security of the system
Table 11 describes physical layer hazards and their security measures in WSN
which tampering and jamming are considered as the main attack in the physical
layer in WSN
141 Principles of security
The security requirement of UAV communication network is as follows (Kumar et
al 2014)
Confidentiality Ensure that only the approved sensor nodes could get the contents
of the texts
bull Authentication Ensure that the data is introduced from the sound source
bull Integrity Ensure that every received text has not been modified to be sent
by unauthorized users
14
bull Freshness Make confirm that no old information has been reiterated
bull Availability services are feasible at any time through WSN or by a single
node
The standard attacks of the physical layer are as follows (Sastry et al
2013)
bull Jamming The transmission of the radio signal can interfere only with radio
frequencies used through WSN which is known as jamming As the
capacity grows it may influence more significant portions of the network
by transmitting other radio signals The opponent will use a few nodes to
occupy the entire channel This state is called physical layer jamming which
results in a denial of service In this scenario the opponent will not be
permitted to have any knowledge but will be capable of preventing
communication to any nodes
bull Tampering Often the nodes tampered through an opponent This mode is
called tempering Here the attackers can destroy exchange and
electronically confront nodes to obtain information from counter measures
towards jamming that have been planned as spread as well as frequency
hopping
bull A security mechanism is used in WSN to track avoid and recover from
security attacks A wide range of security schemes can be devised to counter
malicious threats which can be classified as high and low levels
bull Secrecy and Authentication Most network sensor applications need
protection from eavesdropping packet alteration and injection Early
networks are used for connection layer cryptography as this approach offers
the easiest deployment of network cryptographic solutions
bull Privacy Like all other conventional networks the radio networks have also
brought secret issues to allow Initially sensor networks are implemented
for legitimate purposes and can eventually be used unexpectedly
Knowledge of active sensor nodes as well as the acquisition of data is
exceptionally crucial
15
bull Critical launch and trust setup The primary prerequisite for setting up a
network is the development of keys (cryptography) Sensor devices
typically have minimal computing capacity and public cryptographic
primitives are too difficult to adopt Critical establishment and strategies
need to be scaled to network with thousands of nodes
bull Secure routing Routing as well as data forwarding is a problem that
confronts to facilitate communication in networks Regrettably the latest
protocols encounter a variety of security flaws
bull Robustness of communication Does An opponent challenges to interrupt
the operation of the network
Figure 14 Security problems in the UAV
Figure 14 illustrated the security difficulties in a UAV The physical layer security
in the UAV wireless networks was examined The UAV had affected by both active
eavesdropper and passive eavesdropper This paper proposed the trajectory design
and cooperative UAV for constraining the eavesdropper NOMA MIMO mm-
Wave frequency band in UAV would cause better spectral efficiency and security
(Xiaofang Sun et al 2019)
UAV implementation of the 5G communication was considered advantageous The
UAV was assumed as the novel wireless network technique for the territory users
and their base stations The UAV had resulted in high altitude So the UAV had
16
considered a superior line of sight At the same time the possibility of security
problems was raised in a UAV The secrecy in the existence of eavesdropper the
jammer in the ground was performed using the UAV UAV aided territory security
was proposed The UAV was involved in inspecting the eavesdropper and hazard
jammers on the base stations territory UAV had targeted the global position system
spoofing for assisting the authentic users and performed the role of an artificial
eavesdropper for excluding the eavesdropper and jammers in the ground (H-M
Wang et al 2019)
15 Non-Orthogonal Multiple Access (NOMA) System Secured
Communication
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
151 Comparison of NOMA Vs OMA
Comparison of the NOMA and OMA can be discussed as follows
17
1511 Spectral throughput and efficiency
In OMA a resource is allotted to the distinct user whether it is good or bad in a
channel scenario like OFDMA Thus the whole process moves from less
throughput and performance
While the same frequency is allotted to the multiple-use at the same time with good
or bad channel operation in NOMA here the weak user gets the allocated for the
resources which the strong user can also use it And the interference can be reduced
by the SIC process on the receptor side of the user Consequently the probability
with the increased spectral efficiency as well the high throughput will be
maximized
1512 User fairness and higher lately
A user of fair channel complaints has higher precedence to be served in OMA In
contrast a user with a poor channel complaint is to remain activity which causes
the issue of user fairness and higher latency Yet OMA cannot assist colossal
connectivity Whereas NOMA helps multiple users with various channel
procedures and offers increased fairness massive connectivity and lower latency
1513 Compatibility
NOMA has compatibility with the current and upcoming scenario meanwhile no
need for necessary changes to the previous methods As an instance NOMA has
been bought up in the 3G Partnership Project LTE Advanced (3GPP LTE) Though
NOMA contains many characteristics that can assist the upcoming generations and
it has some restrictions that can be explored with its full benefits Those restrictions
are as follows
bull Each user has to decrypt the signals of other users until decrypted their
signal the complexity of the receiver would be strengthened in NOMA as
opposed to OMA which creates a long pause
bull Also data on channel quality for all users should be returned to the BS but
this results in substantial CSI input overhead Furthermore if any issues
arise to any consumer during the SIC process the likelihood of consecutive
decrypting errors will be improved
18
Figure 15 Comparative analysis of NOMA vrsquos OMA
As an outcome the number of users is reduced to ignore the spread of such
debugging Another aim of restricting the number of users is that there must be
substantial variations in channel revenues between users with different channel
grievances to provide network reliability
16 Problem Identification
The NOMA-based architectures main feature is to configure trusted and untrusted
users when more than one eavesdropper is present in the dense setting of todayrsquos
and future sophisticated wireless communication networks This research aims to
examine the security efficiency suggested for mission-critical applications in the
NOMA-based UAV communication network The proposed system underpins two
user NOMA frameworks The possibility of paring both users was explored with
PHY performance measures in mind Outage probability (OP) and Secrecy Outage
Probability (SOP) Dynamic Optimization Method Programming (DP) and Partially
Observable Markov Decision Process (POMDP) optimization have also been
analyzed to explore the feasibility of achieving an outage-optimal output for the
pair under the heavy users secrecy outage restriction The optimized theoretical
findings are applied to the multiuser scenario The identifications were tested
through a computer model in which POMDP has shown substantial progress over
the dynamic optimization method to program
19
17 Motivation
Unmanned aerial vehicle (UAV) wireless communications have experienced an
upsurge of interest in both military and civilian applications due to its high
mobility low cost on-demand deployment and inherent line-of-sight air-to-ground
channels However these benefits also make UAV wireless communication
systems vulnerable to malicious eavesdropping attacks
Despite the promising gains brought by UAVs the open nature of air-to-ground
wireless channels makes secure information transfer a challenging issue
specifically on the one hand information signals transmitted over wireless LoS
channels are likely to be intercepted by some undesired receivers which lead to a
risk of information leakage On the other hand wireless UAV transceivers are
vulnerable to malicious jamming attacks Hence security plays an extremely
important role in UAV wireless communications Unfortunately traditional
encryption techniques require high computational complexity leading to a large
amount of energy consumption which may not be suitable for UAV systems As an
alternative physical layer security is computationally efficient and effective in
safeguarding wireless communication networks via exploiting the inherent
randomness of wireless channels As a result various physical layer techniques
have been proposed in the literature for guaranteeing communication security
NOMA is viewed as a promising technique to provide superior spectral efficiency
by multiplexing information signals at different power levels [13] Hence it is
expected that NOMA can bring additional rate and robustness to enhance the
achievable rate in UAV physical layer security communications Consider a
scenario where a UAV acts as a relay to facilitate data delivery to two receivers
with different security clearance levels within a maximum cruising duration T The
receiver with a lower security clearance level and a higher potential with an
eavesdropper Since it has a strong motivation in intercepting signals intended for
a receiver with a higher security clearance Then when the eavesdropper suffers
from a bad channel condition NOMA is adopted to forward both confidential and
public information simultaneously Otherwise UAV only broadcasts the public
information for security issues The mode selection between NOMA and unicast is
20
chosen based on the results of the proposed resource allocation optimization In
particular for maximizing the spectral efficiency one needs to jointly optimize the
transmission scheme resource allocation and UAVrsquos trajectory However the
coupled optimization variables generally result in non-convex optimization
problems which are difficult to solve optimally As an alternative an iterative
suboptimal algorithm based on successive convex approximation can be employed
to facilitate a computationally efficient joint design We have discussed that the
NOMA scheme always outperforms OMA in all the considered scenarios which
demonstrates the spectral efficiency advantage brought by NOMA in striking a
balance between public data rate and confidential data rate
The main motive of this research is to enhance the inherently insecure PHY layer
of the NOMA-based UAV communication network NOMA-UAV communication
network requires feasible paring between trusted amp untrusted users (attacker) for
cooperative communication mainly in real-time field applications The power
allocation factor need to be optimized as per the trustworthiness of the associated
users (reliable user) and keeping the outage probability minimum for secured and
cooperative communications The pair Outage Probability and the SOP have been
optimized jointly for feasible pairing between BS amp the associated Users
18 Aim and Objective of the Research
The proposed works main objective is to examine the design of a NOMA-based
UAV communication network for enhanced Physical Layer security (PLS)
features Remarkably it is anticipated infrastructures and resources to connect
numerous devices and provide various services Researchers these days
concentrating on ways to design a heterogeneous framework like deployed small
cells air and ground-based deploy multifarious communication methods in 5G
such as millimeter-wave (mm-Wave) device-to-device (D2D) massive multiple-
input multiple-output (MIMO) Cognitive Radio (CR) and so on for improving
spectrum and energy efficiency
As a critical need especially for emergency applications the adoption of NOMA
transmission of UAV communication needs to be improved PLS A new optimal
resource allocation algorithm for some more robust and stable communication in
21
single and multiuser scenarios has been suggested here The PLS in dense
heterogeneous sensor networks has improved by the feasible pairing of trusted and
untrusted users (K Cao 2019 T Zhao 2018) In the instance of untrusted users
dynamic programming and POMDP are subjected to the channel conditions
details optimizing OP and SOP as a restricted parameter accompanied by resource
allocation (Davis 2018 L Hou 2018)
The main aim of the proposed research work areas
bull To analyze the underlying NOMA UAV communication framework with
enhanced Physical Layer security (PLS) implications for particular quest
applications
bull To examine the potential pairing of trusted and untrusted users in the
NOMA-based UAV contact network with two users and multiuser scenarios
for certain channel conditions called Channel State Information (CSI)
bull To maximize resource allocation among trusted and untrusted users by
pairing OP and Secret Outage Probability (SOP) as performance measures
with the POMDP optimization method
bull To evaluate POMDP and dynamic programming resource allocation with
two users and multiple users for both protected NOMA-based UAV
communication network scenarios
19 Thesis Organization
Chapter 1 Provides the introduction and basic concept of the proposed work with
the problem identification motivation and aim and objective of the proposed work
Here we described LTE 4G and its advanced techniques than about the NOMA and
its basic scheme UAV concepts represent their types and basic working strategy
Chapter 2 Provides a survey of the existing technologies which is related to the
proposed work The NOMA transmission schemes Merits and De-merits related
to security UAV assisted communication in heterogeneous sensor networks UAV
networks of 5G and beyond communications has been explained then about UAV-
NOMA PHY secured communication techniques as well
22
Chapter 3 Describes the proposed work of improvement of physical layer
insecurity of the NOMA The overflow and its performance measures with
simulated output have been defined in this chapter
Chapter 4 Describes Migrations proposed work from 4G LTE to advanced PHY
techniques for UAV communication The overflow and its performance measures
with simulated output have been explained in this chapter Concludes and explains
the proposed work with its outcome and the future scope of the proposed work
23
CHAPTER 2
LITERATURE REVIEW
21 Integration of UAV Networks for 5G and B5G communication
5G and B5G had been anticipated to give a unique connection among universal
users The UAV had been emerged for its advantage of wireless network and
relaying high data rate The UAV in the 5G and B5G was introduced and 5G and
B5G were updated with the new concept of Space-Air-Ground Integrated Networks
(SAGIN) Three layers were established named physical network communication
link and evaluation Besides the usage among the dense population IoT was
applied in satellite communication In which the IoT had provided the uninterrupted
service with high data rate communication The scope for flying UAVs had been
created for enhancing the number of mobile users with IoT (Ali et al 2018)
5G and B5G had projected the UAV as the vital constituent One to multiple point
transmission can be possibly advance in 5G and B5G The structural design of the
upcoming UAV (multi-tier drones) was driven by the routine of different structures
like the maximum functioning altitude communication overlap coverage and
determination The UAVs practicability (multi-tier drones) among conventional
UAVs (single-tier drones) is scrutinized in that perspective By ascertaining the
circumstances UAV (multi-tier drones) could supplement the older terrestrial
networks with RF Initially UAV (multi-tier drones) and drone-aided wireless
networks were related to finding the tasks The modified UAV (multi-tier drones)
and the drone-administered wireless networks were analyzed The enactments of
UAV (multi-tier drones) were scrutinized in the contest of spectral efficiency in the
downlink networks Their effect had exhibited the detailed network parameters The
UAV distribution (multi-tier drones) was considered advantageous for the spectral
efficiency from the downlink transmission over traditional terrestrial wireless
networks (Sekander et al 2018)
The growth of 5G and B5G wireless networks prominently hang on the
incorporation of the terrestrial and aerial systems in innovative heterogeneous
network architecture They had advanced a creative and tangible multiple UAV
24
made up of cluster UAV ndash base stations and Poisson point process with UAV and
mm-Wave frequency band Ground user equipment and UAV had exhibited as the
Poisson cluster process and then spread around the public cluster in the distinctive
cluster In particular the scrutiny was accompanied by the accumulation of extra
tiers Extra tiers were made up of multi-cluster UAV base stations and single ground
user base stations in the characteristic cluster Four-tier network systems were
designed correspondingly from the subdivision of the above-said base stations
Two-tier and four-tier association patterns were built for discovering the
involvement of the cluster networks The coverage probability for the downlink and
network throughput was derived (Ji et al 2020) The numerous subordinate title
role of the multifaceted communication systems was performed by the UAVs The
UAV was acted as the air relay in the maintenance of ground networks The UAVs
were used in the countryside hilly zones whereas the communication was
inadequate The author anticipated resolving the viable communication difficulty in
5G and B5G vehicular ad-hoc The associate communication pattern established on
the smart UAVs was planned given the crisis condition of the car ad-hoc The smart
UAVs were supporting the vehicular ad-hoc strong communication in real
situations Above and beyond its actual characteristics of the vehicular ad-hoc were
needed to be endangered to avoid the prohibited features from attaining and
exhausting for law-breaking practices Innovative UAV with a secret authentication
key arrangement was recommended in the 5G and B5G vehicular ad-hoc Because
of supporting efficiency the vehicle network which guaranteed communication
confidentiality was not negotiated The suggested pattern was confirmed to be
unaffected by numerous outbreaks by exploiting the broadly applied natural or
random ROR scheme
Furthermore the projected scheme had well calibrated the communication
overhead from the performance estimation (J Zhang et al 2020) The UANs had
obtained a phenomenal role in the research area the emergent sector of aerial
robotics The parcel transport organization monitoring occurrence shooting
surveillance and tracing were the metropolises general operations utilizing the
UAV Various domains would use 5G and B5G to improve UAV networks UAV
ecological unit was advantageous in present 5G and B5G mobile communications
For UAVs intrinsic features they were concerned for flexible movement of three-
25
dimensional space independent actions and smart locations These devices were
provided with extensive scope in cellular networks The author proposed an in-
depth assessment of implementing cooperation between UAV and 5G and B5G In
which UAV had been assimilated as a novel user equipment of aerial in present
mobile communications The UAV had implemented the duty of flying users within
the network coverage named the cellular-connected UAVs in this amalgamation
The author showed a broad examination of the incorporation tasks with 5G and
B5G novelties Continued efforts in the prototyping and validation of mobile
communication UAVs were conducted using the ground trial The paper had
focused on the current growth in 3GPP The social-economic had not been taken
into account which was considered disadvantageous (Mishra amp Natalizio 2020)
The UAV was anticipated as the significant constituent in the 5G and B5G wireless
networks 5G enables the UAV to be used in broadcasting and end-to-end
communications using the small UAV They needed a devoted and endangered
aerial spectrum in the aircraft cargo by letting small UAVs run in space in
supervisory authority The security information was obtained from the link Control
and Non-Payload Communications (CNPC) The security information contained
the regulation of UAV and the line of sight of terrestrial The CNPC application in
the 5G and satellite communication was scrutinized in this paper Payload
communication like mm-Wave networks and UAV were analyzed in this paper The
direction-finding and reconnaissance difficulties were examined UAV
communication systems were scrutinized and the hardware challenges were
discussed (Hosseini et al 2019)
The potential gain from the UAV-assisted data gathering was found in
indiscriminate IoTs The characteristic propagation was represented by utilizing the
complicated channel method (contained small- and large-scale fading) IoTs were
updated in constrain of transmit power (in high) and total energy The multi-antenna
UAV was selected in the IoTs in sequence The virtual MIMO was created by the
communication between UAV and singe antenna IoT in every transmission (W
Feng et al 2018)
The UAV was applied in the aerial coverage surveillance agricultural prediction
constructional areas and power line supervising and blood donation The flight
26
period increment payload capability fast movement and speedy placements were
implied features in the UAV so that the UAV was exploited by the applications of
5G and B5G (Ullah et al 2020)
The UAV was considered a motivation for many emergent usages and reformed
social-economic welfares The wireless networks for the UAV and the base stations
were desired for the UAV function Mobile communications were considered
suitable for finding tracing and regulating the flying UAV The wireless
communications were selected for their features of broad coverage quality of
service and secrecy The wireless communication in the UAV improved
productivity besides the line of sight (G Yang et al 2018)
22 UAV-NOMA in Physical Layer Security enhancement
The NOMA has been applied in the fifth generation (5G) technology The Multicast
Cognitive Radio (MCR) network is implemented using the NOMA and coined as
MCR- MOMA The transmission side is also included with the superimposition
code The decoding was applied at the receiving end So an unknown user is
deduced in their methodology (Meng et al 2020)
The physical layer security for the cooperative NOMA was examined Amplify
and forward decode and forward were taken into consideration for achieving
secure transmission (Chen et al 2018)
The physical layer security of the NOMA was analyzed in the broader network with
varying locality The single and multi-antenna were established in the following
cases The single antenna was taken for an end-to-end connection in a secured
manner And the multi-antenna was used for the connection of base station and
random user Finally achieved security for the multi-antenna on the transmission
side The security of the single antenna was attained by introducing the excluding
area for eliminating eavesdroppers The individual expression of security outage
probability for both single antenna and multi-antenna were derived (Yuanwei Liu
et al 2017)
The secure transmission of NOMA in large-scale applications was investigated
Stochastic Geometry was utilized for placing the eavesdropper and user nodes The
equation for secrecy outage probability was derived and expressed for evaluating
27
secure transmission Security can be improved by expanding the protected zone
(Qin et al 2016)
The power domain NOMA had the disadvantage of decoding data by other
unauthentic users of the same source For reducing unauthentic users the base
station should treat the unauthentic users with different cleaning methods The
secrecy outage probability was investigated for authentic users and unauthentic
users Both users were combined as a pair to the non-uniform distribution of original
and unauthentic users The pair outage probability of genuine users from the secrecy
outage probability restrained NOMA authentic users The derivation for pair outage
probability and the secrecy probability were expressed for calibration The
combined system had been the better security (ElHalawany amp Wu 2018)
The physical layer security was considered problematic in the wireless networks
mainly for keeping the authentic userrsquos data The UAV was acted as the base
station UAV based base station had sent the extensive data to the original users
NOMA with the multi-antenna with mm-Wave frequency band transmission had
enhanced the spectral efficiency The physical layer security was attained by
announcing the space around user locality as the eavesdroppers protected zone
Covering the entire eavesdropper area was considered a resource-consuming way
The shape optimization for the protected location in each UAV base stations
altitudes was introduced The derivations for the secrecy sum rate and the secrecy
outage probability were expressed (Rupasinghe et al 2018)
The vehicular communication system had used cooperative NOMA The secrecy
outage probability was considered in vehicular communication The relay can be
used in both modes (half-duplex and full-duplex) in vehicular communication The
closed derivation for the secrecy outage probability was expressed The security of
the full-duplex NOMA resulted better than that of the half-duplex NOMA The
limitations are that the velocity of the vehicles was not considered Figure 21 is
illustrated the conceptual model of the vehicular communication NOMA system
(Xie et al 2019)
28
Figure 21 Vehicular communication NOMA system
The physical layer security of the uplink NOMA of the large-scale devices was
examined The connection networks had investigated with the approach called
stochastic geometry The new derivation was expressed for the coverage
probability The protected zone restrains eavesdroppers to the authentic users
Efficiency secrecy throughput was examined wiretap channels and the many
original users Constant transmission and variable transmission were collectively
inspected The signal to noise and the movement to interference ratio were derived
drastically (Gomez et al 2017)
The wireless system was executed using Space-Time Block Coding (STBC)
approach in the NOMA of mm-Wave MIMO The technique focused on haphazard
users So the pairing method was introduced mainly for Random Near-Random Far
(RNRF) Here the latent period could be minimized and the RNRF has also been
deduced for the overhead issue The result revealed the systems efficiency with a
proper implementation (Ghavidel et al 2020)
The recent arbitrary beam forming method was proposed in the multiple access
NOMA The pairing had decided to the user places So the evaluation was focused
on the system overhead The result revealed that the proposed work outperformed
29
the existing methods (Aghdam et al 2020) NOMA enhances the reliability of
multi-users transmission The sum rate could be reduced for improving Quality of
Service (QoS) power transmission and signal outage probability The
eavesdropper easily accessed the multi-access systems that cause physical security
during transmission (Z Li et al 2020)
The NOMA had provided spectral efficiency speed transmission of data multiple
networking and less latent period The NOMA utilizes the power domains for
various access Cognitive Radio Networks (CRN) is used to screen illegitimate
users The legitimate users were only permitted in the CRN by the Primary User
Networks (PUN) QoS The cooperative NOMA here implemented with the PUN
and the system performance is enhanced The spectral efficiency can be improved
by the secured transmission The cooperative NOMA was additionally developed
in the CRN with the PLS A new method of cooperative NOMA in the CRN was
examined The PUN technique attains a secure transmission Multiple antennae
were used in this study for reliability and the eavesdropperndashexclusion zone method
is used for better security (B Li et al 2018)
The downlink NOMA for moderate CSI was examined The challenge of the power
domain was rectified by allocating power NOMA The power in NOMA and that
of the OMA was analyzed which resulted in a significantly reduced NOMA (Cui
et al 2016)
Here the users were multiplexed by the power domain So the method was coined
as power domain NOMA The demand arising from the B5G (Beyond 5
Generation) had reached using power domain NOMA Machine learning in the
NOMA was described (Maraqa et al 2020)
The uplink NOMA with the PLS was proposed The uplink NOMA contained a
single base station and multi-users a couple of users combined for NOMA The
known jammer emitted the pseudo-noise to divert the eavesdroppers The study had
suggested the two jammers in the uplink NOMA for secure transmission (N Zhao
et al 2020)
The Intelligent Reflecting Surface (IRS) is designed using downlink NOMA The
multi-access had used the space direction of the beams of closure users The IRS
30
had performed the multi-access for every spatial order by the cell edge users of the
orthogonal beams (Ding amp Poor 2020)
The multi-input single-output NOMA has introduced the technique called Secrecy
Beam Forming (SBF) SBF had utilized the artificial noise for NOMA security
aided users in which the eavesdropperrsquos channels deteriorated The SBFs secure
transmission can be achieved in which high successive interference cancellation is
gained (L Lv et al 2018)
The superposition coding was performed in the transmission pat The successive
interference cancellation was conducted in the receiving position These two
techniques were combined in the novel 5G aided NOMA The basic concepts of
uplink and downlink NOMA were mentioned The dominant condition was
performed in the two user clusters of NOMA The prevailing state had issued the
confirmed spectral efficiency gain in NOMA (Tabassum et al 2016)
The relay scheme in IoT was examined for the secrecy of NOMA This was coined
as relay selection NOMA The base station had transmitted the secret messages to
the two NOMA-aided sensors and eavesdroppers IoT had treated the sensors and
eavesdroppers with different power allocations The expression for certain outage
probability and the strictly positive secure capacity was derived Increasing the
number of the relay would enhance the security in the NOMA-aided IoT The
outage probability for NOMA and OMA were compared The NOMA resulted in
better outage probability in Decode and forward mode (Do et al 2019)
31
Figure 22 RS-NOMA against an external eavesdropper
The NOMA-aided IoT was utilized to fight against the external eavesdropper as
Figure 22 The secured NOMA was proposed The base station sent secret
messages to several authentic destinationsmdashseveral eavesdroppers and unauthentic
users
Nakagami-m fading model was carried out using the multiple antennae in the
channel The security was attained using the max-min transmit antenna selection
scheme Both authentic and unauthentic eavesdroppers were analyzed The closed
derivation for the cumulative distribution of the original user was expressed first
That was compared with the unauthentic user The derivation for the secrecy outage
probability was obtained to identify the level of secrecy performance (Lei et al
2018)
Reconfigurable intelligent surface (RIS) aided NOMA was established for the
secrecy performance The main disadvantage of this model was the chance of using
RIS by the eavesdropper The secret outage probability was derived in this paper
The RIS improved the secrecy of the traditional NOMA The eavesdroppers were
limited from receiving the RIS signal by enhancing the number of intelligent
elements in the RIS A high signal-to-noise ratio was obtained from this experiment
(Liang Yang amp Yuan 2020)
32
The cooperative relaying NOMA was proposed for improving private transmission
in wireless networks Full duplex mode transmitted the jamming signals That
received the required communication at first Secondly the jamming signal
emission was sent by the base station The power allocation for the jamming signal
and information signal was decided on the eavesdropper channel state information
The eavesdropper was jammed by the signal from the first phase with maximum
power Second the derivation of the secrecy outage probability was expressed by
static eavesdropper CSI (Y Cao et al 2020)
The NOMA achieved spectral efficiency and secrecy The security of the multi-
NOMA users was obtained by the successive interference cancellation (SIC)
decoding in the receiving node The conservation of the untrusted NOMA was
concentrated in this study The security can be confirmed by the properly secured
decode processing and allocating power The decoding scheme was implemented
for aiding NOMA users The decoding was performed for enhancing the sum-rate
(Thapar et al 2020) The cognitive radio network in NOMA with the external
eavesdropper was proposed (Mehr et al 2020)
The cooperative NOMA was used in the field of energy harvesting communication
The novel relaying technique was introduced for achieving secrecy The secrecy
outage probability was derived and the derivation was expressed for the three
conditions The first condition was the derivation of CSI with a passive
eavesdropper The second condition was the derivation of CSI with the unauthentic
eavesdropper The third condition was the derivation obtained from the multi-relay
nodes The increased SNR resulted in high security The increase in the number of
users deduced security This was considered a disadvantage (Salem et al 2020)
Satellite communication covered more range of broadcasting So the security
challenge was considered a big difficulty in satellite communication Downlink
NOMA was assessed with an eavesdropper for the examination of secrecy The
paper concentrated on the physical layer security of downlink satellites Here two
methods were proposed The frequency-domain NOMA was considered for gaining
spectral efficiency The multiple user interferences were obtained in the process of
overlapping Introducing a suitable technique can be performed the security for the
number of users The secrecy rate was analyzed for all authentic users (and the
33
eavesdropper) and expressed in the derivation The safety was improved using the
spectral overlap method (Yin et al 2019)
The NOMA was considered as the emerging scheme in the upcoming wireless
networks The secrecy sum rate for the downlink NOMA (with MIMO multiple
inputs multiple outputs) was examined Downlink NOMA had the base station
number of users and the eavesdropper In the limitation of transmit power and
optimal successive interference cancellation the security was expected to enhance
Downlink MIMO NOMA was considered advantageous because of its secrecy
performance and the practical usage of bandwidth The mutual information rate and
the mean square error were causing the secrecy rate optimization to the problem of
biconvex This was rectified through the alternative optimization method and the
second-order cone programming was solved (Tian et al 2017)
Table 21 Comparative analysis
The comparative analysis for the physical layer security was examined in existing
studies
SR
No
Details of Author wise Contribution to NOMA Technology
1 Author (YFeng Yang amp Yan 2017) Secrecy performance in NOMA was
conducted with the help of artificial noise in the full-duplex mode of relaying
Methodology The optimization of the power was calibrated for the source
information and the noise signal The closed derivation for the secrecy outage
probability was expressed
Usage and limitations The physical security was increased
34
2 Author (He Liu Yang amp Lau 2017) NOMA was developed in the constrain
of security
Methodology The secret message had been sent to some users and also to the
eavesdropper The Novel decoding process was conducted for excluding the
unauthentic users The iterative algorithm was used for power optimization
Usage and limitations Transmit power was reduced The quality of service
was availed
3 Author (D Wang et al 2020) The secrecy was performed in the NOMA
The security was developed against the eavesdropper outside
Methodology The channel state information was analyzed for secrecy The
quantization of CSI had performed for secrecy The derivation for the secrecy
and transmission outage probabilities were obtained
Usage and limitations The secrecy rate was enhanced
4 Author (L Lv et al 2020) The physical security of the NOMA was
improved by adding artificial noise jammer and inter-user interference The
mode of full-duplex in the updated version was used in the NOMA
Methodology The eavesdropper can be trapped the superimposed signal from
the source So the secrecy was affected
Usage and limitations The spectrum usage is effective in the NOMA
transmission scheme Numerous connections can be performed in the NOMA
NOMA is considered to be the most advantageous for the upcoming
generation communications The superimposition technique was followed
4 Author (Yue et al 2020) Secrecy performance of the NOMA was developed
with a unique framework
Methodology The eavesdroppers inside the zone and outside the coverage
zone were examined properly in this paper The outage probability for codendash
power domain NOMA was derived
Usage and limitations Safety was acquired for both internal eavesdropper
and external eavesdropper in this scheme
35
5 Author (Guezouli et al 2020) The heterogeneous sensor network of cellular
communication was taken into account
Methodology Unmanned aerial vehicles are utilized the heterogeneous
sensor network of cellular communication
Usage and limitations Extended the life span of the network system The
cost of the hardware components is drastically low The random and the
repeats in the speedy movement The latency is maximized The coverage
period is maximum
6 Author (Yao amp Xu 2019) The security in transmitting a large amount of
information in the wireless network systems are analyzed with unmanned
aerial vehicle UAV
Methodology The numbers of UAVs are arranged in the space The base
station sent the information to the UAV in the space The authentic receivers
have obtained the secured information from the UAV The HPPP
homogeneous Poisson point process is used for distributing the authentic
receiver and eavesdropper in the line of sight
Usage and limitations The increase in the number of safety zone causing the
secured transmission
7 Author (Saacutenchez et al 2020) Physical security can be achieved by the
method of a unique encryption scheme
Methodology The physical layer security of the following schemes is
discussed in this paper mm-wave NOMA massive multi-input multi-output
heterogeneous sensor networks full-duplex mode
Usage and limitations The physical layer security was analyzed for the 5G
supporting technologies Good reliability achieved The less latent obtained
Machine-type communications can be enabled
36
8 Author (Hou et al 2018) The multi-antennas were used in NOMA with
UAV The stochastic geometric approach was examined
Methodology The multi-input multi-output kind of NOMA was utilized In
common the stochastic geometric approach was used for drastically moving
NOMA
Usage and limitations The maximum signal-to-noise ratio was obtained in
this scheme Power optimization was achieved The path loss is less Good
spectral efficiency was obtained
9 Author (Miao et al 2020) The broadcast type of communication was
performed The less weighed three-dimensional space for 5G communication
was analyzed
Methodology Both the performances of multicast and broadcast were
enabled UAV-assisted 5G communication systems are emerging in the
upcoming wireless networks
Usage and limitations Better flexibility in the network Continuous mobility
One lined line of sight
10 Author (Majhi amp Mitra 2020) The secure communication in cognitive radio
by NOMA was propounded
Methodology The antenna strategy of giving minimum outage probability
was concluded from this study
Usage and limitations The limitation is that more spectral efficiency causes
security issues
11 Author (X Zhao amp Sun 2020) Secure communication of the physical layer
in Visible light NOMA Communication was proposed
Methodology Energy optimization in security constrain was propounded for
achieving overall performance
Usage and limitations It is difficult to find optimal results because energy
optimization is the nonconvex issue
37
12 Author (Tuan amp Hong 2020) Secure communication in simultaneous
wireless information and power transfer NOMA was remitted
Methodology Eavesdropper is used for security purposes between the user
and base station using energy relays Known jammer is used for secure
transmission For energy efficiency storing and transferring were propounded
Usage and limitations Jamming requires extra power allocation
13 Author (Vaezi et al 2019) NOMA for 5G in mmWave MIMO cooperative
and cognitive were analyzed in this study
Methodology SWIFT NOMA is useful for weak receivers
MIMO using more antenna
Usage and limitations multi-antenna utilization cause high power
consumption
14 Author (Vaezi et al 2019) Mobile edge computing NOMA was proposed to
optimize power
Methodology Minimum latency and less power consumption
Usage and limitations Transfer power allocation must be calibrated
15 Author (Faraji-Biregani amp Fotohi 2020) Security in UAV communication
was proposed by introducing mobile agents
Methodology Malicious user of UAV was identified
Usage and limitations Three-phase power is essential
16 Author (G Zhang et al 2019) Secure communication in 5G UAV was
propounded by joint trajectory carrying out in physical layer
Methodology Power optimization was proposed for security
Usage and limitations Security in the physical layer was achieved by
optimization of trajectory
17 Author (Fotohi et al 2020) Agent-based self-protection was propounded in
UAN for secure communication
Methodology This method imitates the immune system of human beings
Less cost
Usage and limitations Energy is not optimized properly This approach
needs to consider other malicious attackers
38
18 Author (Shang Liu Ma amp Fan 2019) Vehicle to everything approach was
propounded for security in a UAV
Methodology Security of vehicle to the vehicle was proposed by considering
eavesdroppers active and passive attacks
Usage and limitations High price
19 Author (Kantor et al 2017) The flight path was calibrated in a UAV
Methodology Security performance was achieved by encryption as well as
anonymization
Usage and limitations High in cost and hardware structure occupies more
place
23 Research Methodology
The NOMA-based cellular architecture for UAV communication has been
considered here as reference network architecture Rayleigh fading has been
assumed as a channel characteristic The performance parameters for PHY layer
security are (1) Pair Outage probability (Pair OP) between two users trusted near
user designated as U1 and untrusted far user designated as U2) and (02) Secrecy
Outage Probability (SOP) of trusted near user designated as U1 The aim is to
achieve optimal Pair OP for the given constrained SOP of User U1 so that network
resources can be efficiently allocated to both users without compromising the
secrecy of trusted User U1
The mathematical analysis from reference literature (ElHalawany et al 2018) has
verified and supported the joint optimization of the Pair OP and SOP for the given
power allocation factor in NOMA This research work is extended as providing
more efficient resource allocation using the POMDP algorithm in a given scenario
First the varying distance of untrusted user U2 from BS as a critical selection
parameter that affects Pair OP amp SOP of user U1 and U2 both has been simulated
and the feasible and infeasible pairing of both users have been analyzed The
optimal power allocation factor for feasible pairing as the constrained problem is
optimized by opting for POMDP as a resource allocation algorithm wherein the
SOP of user U1 is strictly maintained for given CSI POMDP provides optimum
39
power allocation factor for trusted and untrusted users pairing as shown in the
proposed flow of POMDP algorithm is used to model a variety of real-world
sequential decision-making problems After the BS has been set up the distance
between the BS and the user is calculated and if space is less than 200m it is
defined as a trusted user While if the range is more than 200m it is described as
untrusted users In the case of trusted users the channel state information (CSI) is
provided to the proposed algorithm POMDP for reliable and efficient resource
allocation
24 Summary
UAVs play a central role in providing network service recovery in a disaster-
stricken region enhancing public safety networks or handling other emergencies
when Ultra-Reliable Low-Latency Communication is required In particular UAV-
assisted communication can be regarded as an important complement to the 5G
cellular networks Surveyed literature related to UAV communications published
over the past several years emphasized the cybersecurity and channel modeling for
UAV communications etc Security is one of the critical issues in communications
Modern communication networks are based on the layered architecture from the
physical layer up to the application layer A great deal of effort has been made to
develop the cryptographic protocols above the physical layer However the
physical layer is not as robust as that in wired communications The physical layer
in wireless communication is more complex than the counterpart in other
communication paradigms The concerns come from not only the noises but also
many types of fading Recently there has been an influential interest in studying
the security issues in the physical layer Security is highlighted as another
challenge and the implementation of physical layer security techniques is seen as
a difficult task PHY security in NOMA systems under the presence of external
eavesdroppers or untrusted relay nodes Upcoming 5G networks for unpredicted or
crisis (disaster management) the placement of terrestrial substructures is
economically infeasible and challenging due to high operational expenditure as well
as sophisticated and volatile environments
To address such novel issues intelligent heterogeneous architecture by leverage
UAV has been well-thought-out to be a promising novel model For advancing the
40
performance of the UAV 5G communication system physical layer techniques are
of many effects as they have impacted the applications of UAVs Security of
NOMA-based UAV communication network has been scrutinized for optimization
as physical layer security
41
CHAPTER-3
SYSTEM MODEL FOR NOMA-UAV
COMMUNICATION
31 NOMA-UAV System Secured Communication for 5G
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
311 The basic scheme of NOMA
The NOMA system allowed several users to be served simultaneously by the
transmitter To transfer a linear combination of different signals towards the
recipient the system of proportional representation superposition coding (SC) The
transformed signal is provided through
σ ඥ119875119896 119878119896119870119896 =1 -------------------------------------- (1)
Where 119927119948 represents the transmit power assigned toward user k th
119930119948 indicates the normalized message used for user k th
42
The instantaneous total converses power is σ 119927119948119922119948=1 The received signal at user kth
and the eavesdropper are offered through
119910119896 = ℎ119896 σ ඥ119875119896 119878119896119870119896=1 + 119899119896 -------------------------- (2)
119910119890 = ℎ119890 σ ඥ119875119896 119878119896119870119896=1 + 119899119890 -------------------------- (3)
Where 119951119948 and 119951119942 indicated the zero-mean Additive White Gaussian Noise
(AWGN) at user k th with variance 1205901198962 and the zero mean AWGN at eavesdropper
with variance 1206481199422 respectively We assume that the noise variances at all the users
are identical
ie 12059012 = ⋯ = 120590119896
2 = 1205901198902
As per NOMAs process the SIC is followed by all users to decrypt the message to
the same decoding order Notice that it is not known what the optimal decoding
order is for the NOMA method that corresponds to secrecy
Therefore the mth message to be encoded to the user might not be the mth message
to the user As such we also have to add the π variable For example if 120587(1) =
3 then the first message to be decoded for the SIC is the message for the user 120645(119947)
forall j lt k before decoding its letter to remove the inter-user interference successively
Then the user 120645(119948) denotes its message while treating the news for all the user
120645(119946)foralli gt k as the interferences The received Signal-to-interference-plus ndashnoise
ratio (SINRs) at user 120587(119896) k lt K and user 120587(119870) to decode their messages are
respectively given by
119878119868119873119877120587119896=
120574120587(119896)119875120587(119896)
1+120574120587(119896) σ 119875120587(119894)119896119894=119896+1
119896 lt 119870 --------------------(4)
119878119868119873119877120587119870= 120574120587(119870)119875120587(119870) --------------------------------------(5)
Were 120574120587(119896) =หℎ120587(119896)ห
2
1205901199062
൘
43
Also the acknowledged SINR at user 120587(119898) to decrypt the message 120633120645(119948) 119896 lt
119898 le 119870 is given by
119878119868119873119877120587119896=
120574120587(119898)119875120587(119896)
1+120574120587(119898) σ 119875120587(119894)119896119894=119896+1
kltmle 119870 --------------(6)
Similarly the acknowledged SINRs by the eavesdropper of the message 120575119896 119896 lt
119870 and the message 120575119896 are respectively given by
119878119868119873119877120587macr
119896=
120574119890119875120587(119896)
1+120574119890 σ 119875120587(119894)119896119894=119896+1
klt119870 ----------------- ------(7)
119878119868119873119877120587macr
119896=
ȁℎ119890ȁ2119875120587(119896)
1205901198902 = 120574119890119875120587(119896) klt119870 ---------------------(8)
Where 120574119890=ȁℎ119890ȁ2
1205901198902൘
Notice that here expressions for the obtained SINRs at eavesdropper overestimate
the skill of eavesdropper Here a worst-case inference from the viewpoint of
legitimate users is made That is the messages have already been decrypted by the
eavesdropper for all users π (j) forall j lt k before attempting to decrypt the message
for the user π (k)
The presumption also assumes that the decrypting order and power distribution are
understood by the eavesdropper The eavesdropper may or may not recognize the
decoding order of the users and the allocation of power may or may not recognize
the messages for all users π (j) forall j lt k before attempting to decode messages for
users π (k) However since the eavesdropper has been unable to alert the authorized
customers of its capacity and the current CSI the approved user would be unable
to know the eavesdroppers details Therefore we have to pursue the worst-case
scenario for the permissible users point of view due to the liberality required by the
safety reports It highlights that the worst-case assumption in the study and design
of transmission schemes with secrecy requirements has been generally adopted
The proposed study has been evaluated using performance measures Here we
analyze NOMA with downlink and uplink networks suggested by SINR and Sum
44
Rate survey High SNR is then simulated to contrast the OMA and NOMA
processes
312 Downlink of NOMA
The Downlink of the NOMA network on the transmitter side is described in Figure
31 SIC method is supposed to be carried out successively on the receiver side of
each user until another signal is restored The coefficients of users are owed in an
inversely proportional manner based on their available bandwidth
Figure 31 Downlink NOMA network
A consumer with a poor available bandwidth has a transmission capacity of a
higher range than a consumer with strong available bandwidth As a consequence
the consumer with the higher power assumes the signals of other users to be noisy
and automatically restores the signal without conducting any SIC operation The
receiver of each consumer detects indications that are stronger than those of the
desired signal These impulses are then deducted from the power and this process
continues until the signal has been calculated Both users decrypt their signaling by
considering other users with lower correlations The signal is calculated as
45
119904 = σ 119886119894119875119904119883119894119871119894=1 -----------------------------------------------(1)
Where Xi is the user ithrsquos information through unit energy
Ps is the capacity of transmission at the BS
ti is the coefficient of power assigned for user i
Although without the need for lack of generality the channel profits are expected
to be graded as ȁℎ1ȁ2 le ȁℎ2ȁ2 le ⋯ ȁℎ119871ȁ2
Where 119945119923 is the coefficient of the channel of the user Lth
The received signal of the Lth user is calculated as
1199101 = ℎ119897119904 + 119899119897 = ℎ119897 σ ξ119886119894119875119904119883119894119871119894=1 + 119899119897 -----------------------------(2)
Where n1 is zero mean Complex Gaussian noise with a variance of 1206482SINR
analysis with the equation (2) the SNR of Lth user to identify the user 119895 le 1with
119895 ne 1
119878119868119873119877119871 = 1198861120574 ȁℎ1ȁ2120574ȁℎ1ȁ2൘ σ 119886119894 + 1119871
119894=119871+1 ------------------------(3)
Where 120632 = 1198751199041205902ൗ represents the SNR
Sum rate analysis After identifying the SINR of the downlink the sum rate will
also be done quickly
The NOMAs downlink data rate of Lth user can be calculated as
1198771119873119874119872119860minus119889 = 1198971199001198922(1 + 119878119868119873119877119871) --------------------(4)
313 Uplink of NOMA
The Uplink NOMA is depicted in Figure 32 where each user sends a signal to the
BS SIC iterations are supported to classify the signals of mobile users If both
channels are identical and BS sends the coefficients of power allocation to mobile
users the received signal can be interpreted as a synchronous uplink to the NOMA
46
119955 = σ ℎ119894ඥ119886119894119875119909119894119871119894=1 +n ----------------------------------(5)
Where hi is the coefficient of the channel for the ith user
119927119961119946 is the extreme transmission capacity supposed to be general to all users
N is zero-mean Gaussian noise with a variance of 1206482
Figure 32 Uplink NOMA
Analysis of SINR The BS decrypts the signals of the users as per the coefficients
of the users and the SINR for the Lth user can be defined as
119878119868119873119877119871 = 119886119897120574ȁℎ119897ȁ2120574 σ 119886119894ȁℎ119894ȁ2 + 1119897minus1
119894=1൘ ----------------------------(6)
Where 120574 = 1198751205902ൗ indicates SNR
Analysis of Sum rate The sum rate of uplink NOMA when 120632 minus infin can be
computed as
119877119904119906119898119873119874119872119860minus119906 asymp 1198971199001198922(120574 σ ȁℎ119897ȁ119871
119894=1 2 ------------------------ (7)
47
314 Comparison of NOMA and OMA
The attainable data rate of the Lth user of OMA intended for both uplink as well as
the downlink is estimated as
119877119904119906119898119874119872119860 = σ 120572 1198971199001198922120574(1 +
120573119897ȁℎ119897ȁ2
120572119897119871119894=1 ) --------------------------(8)
Just for convenience two users should evaluate the summation of uplink rates for
NOMA and OMA The use of both the uplink rate of NOMA and OMA at high
SNR can be calculated as---
119877119904119906119898119873119874119872119860 asymp 1198971199001198922(120574 ȁℎ1ȁ2 + 120574ȁℎ2ȁ2 ------------------------- (9)
equation (7) and (8) it is seen that 119877119904119906119898119874119872119860 le 119877119904119906119898
119873119874119872119860
Here we note 119929119956119958119950119926119924119912 le 119929119956119958119950
119925119926119924119912 shows that NOMA performed better than OMA in
terms of sum rate in both downlinks as well as uplink of two user networks
The sum rate will be calculated after the SNR as the formulation is shown In this
proposed work multiple users are propagated to the process of NOMA and here a
comparison of NOMA as well OMA has been defined The NOMA uplink and
downlink using the OFDMA method for the
32 PLS performance metrics in NOMA -UAV communication
This chapter mainly describes the proposed work to examine the availability of the
outage probability of the pair below an authorized user According to the decryption
of SIC availability and spectrum sharing the unauthorized user can function as an
eavesdropper and obtain an outage probability (OP) for all situations with the
Secrecy Outage Probability (SOP)
321 SOP and OP - two user and multi-user NOMA system
NOMA system has the capability for assigning multiple data over the transmission
signal through high-level coding (Shim amp An 2018) Thus it contains spectrum
efficiency when opposed to OMA But this has a limitation in security As an
48
instance if the eavesdropper is reached then it obtains multiple user data in the
interference of the NOMA signal Thus the security issues are more significant in
this system Here PLS is an available method to rectify the attack intended for
malicious users (Dai et al 2015)
Additionally data should be transmitted confidentially if the root and eavesdropper
networks can be evaluated and the recipient can decrypt the received text At the
same time the eavesdropper is not able to solve the text that has been interrupted
PLS is at the cutting edge of wireless communication security technology to prevent
eavesdropping attacks The SOP is described as the likelihood that the near users
attainable device confidentiality capability will fall under the predefined target
confidentiality rate as set out in (Shim et al 2017)
Through SOP we can calculate the level of protection of the device As an example
the low-secret OP system makes the system more stable in terms of security than
the high SOP system To boost the efficiency of the PLS CSI-based opportunistic
scheduling links to a scheduled destination in a particular time slot It has been
documented as an enticing scheduling scheme (Long Yang et al 2016) because the
various wireless channel has been exploited Opportunistic scheduling is also
considered to be one of the strategies used to increase the confidentiality efficiency
of the NOMA method
322 System Model
Suppose a multi-user NOMA system of downlink containing BS a selection of K
nearer users as N= 119873119894ȁ12 119870 and a range of M far users as F=
119865119895ȁ12 119872 and an eavesdropper E as displayed in Figure 33 More
specifically nearer users should make active use of the SIC methodology to
distinguish far user F Both the legitimate and illegitimate receivers are furnished
through a single antenna and operate in a half-duplex manner
49
Figure 33 Multi-two user architecture of NOMA system (Shim amp An 2018)
Here 119945119935119936 and ȁ119945119935119936ȁ2
Where X120598ሼ119878ሽ 119884120598119873 cup ሼ119864ሽ represent the channel coefficient and the corresponding
channel gain of the X-Y value
Taking into consideration that each wireless channel for Rayleigh block fading 119945119935119936
can be incorporated as an independently distributed random Gaussian variable with
zero mean and affirmative ℷ119935119936 Variance The outcome of channel gain ȁ119945119935119936ȁ2is an
exponential variable randomly through the Probability Density Function (PDF)
119891ȁℎ119883119884ȁ2(119911) = ቀ1
ℷ119883119884ൗ ቁ 119890119909119901 (minus 119911
ℷ119883119884ൗ )
if zge 0 119900119905ℎ119890119903119908119894119904119890119891ȁℎ119883119884ȁ2(119911) = 0 -----------------(1)
Especially the average channel profit can be represented as
ℷ119883119884= ൬119889119883119884
1198890൘ ൰
minus휀
ℒ ------------------(2)
When 120027 is the attenuation of the received signal 119941119935119936 signifies the distance among
X and Y 1199410 indicates the space and 120656 is the exponent of the path loss It is believed
that the source is entirely familiar with the CSI of both legitimate users and
eavesdroppers
50
323 Partially Observable Markov Decision Process-POMDP
Figure 34 Flow Diagram of the proposed system
The proposed overflow is shown in Figure 34 After the BS has been set up the
distance between the BS and the user is calculated and if space is less than 200m
it is defined as a trusted user While if the range is more than 200m it is described
as untrusted users In the event of untrusted users the channel state information is
accessible to the POMDP accompanied by the allocation of resources The study
was carried out after the machine operation Here a NOMA-oriented cellular setup
provided with a BS at the Centre and two users was described in Figure 35
51
Figure 35 Near and Far User
The adjacent user has a high level of security confirmation needed to protect the
layer since the low-security clearance user is situated at a distance away from the
BS P is specified as the highest level of transmitting power In this chapter it is
presumed that all DNS servers are furnished utilizing an individual antenna and all
channels are supposed to be individually static identical to the Rayleigh
dissemination concerning distribution
119862119873(0 120575119898
minus120572
212059601 2Τ
)
In which 120633119950 is the range between the BS and the nodes 119932119950 Here the path-loss
exponent and constant are defined as 120630 and 1206540 Furthermore BS is assumed to
have predicted the position of the user so that a better CSI can be obtained at BS
that is elaborate in user pairing
The BS transmits the superimposed mixture
119909119905 = ඥ1199051199041 + ඥ1 minus 1199051199042 ------------------------------- (3)
In which 1199561 and 1199562 are the unit of power signals received by users 1199321 and 1199322
respectively t is the power allocation coefficient for the adjacent user
1199031 = ℎ1119909119905ξ119875 + 1198991 ------------------------------- (4)
1199032 = ℎ2119909119905ξ119875 + 1198992 ----------------------------------(5)
Where 1199451119886119899119889 1199452 the channel profit link with the fading of small scale since the
BS to the user 1199321 and 1199322 respectively The additional Gaussian noise with variance
52
is denoted 1199511 119886119899119889 1199512 and zero mean 119894119904 119889119890119899119900119905119890119889119886119904 (1199250) and it is assumed
that the BS conveyed SNR is 120646 = 1199271199250
ൗ
In the NOMA technique additional users with more power may decode their signal
by recognizing the adjacent signal as noise without decoding the adjacent user
message In the previous equation 1198801 is supposed to first solve a weak signal by
decoding its own SIC signal1198802 which is an unauthenticated user attempted to
decrypt the nearer user text after decrypting the adjacent usage text after decoding
its own SIC message The following equation has therefore been achieved
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2 ----------------(6)
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2 ----------------(7)
119879119900119905119886119897119904119894119899119903 = 11987811986811987311987721 1198781198681198731198771
1 119878119868119873119877221198781198681198731198771
2 -----------------(8)
Where 119930119920119925119929119950119951
indicates the SINR ratio of user mth that was decoded by 119932119951 for
119898 119899 isin ሼ119894 2ሽ and the channels gain followed an exponential distribution with the
parameter 120649119950=120654120782120633119950minus120630
324 Problem formulation
As a result the BS could achieve and provide better communication for users who
are vulnerable to security threats from unauthenticated users the proposed
framework identified two kinds of QoS energy efficiency that could be considered
essential for addressing the problem In a particular study a pair of OPs was
specified to check the reliability at which the attainable data rate for users is equal
to or greater than the threshold of minimum reach The following issue aimed at
reducing the pair OP to an SOP factor intended for the user 119932120783 that is provided by
Where 1199270is Outage Probability- (OP)
1199271 is Secrecy Outage probability user U1 119930119926119927(119932120783) and
120631 the permissible SOP threshold
53
33 Performance Analysis Improving PLS Insecurity of NOMA
System
331 The Pair OP Calculation
Through Shannons capacity formula and assuming 119914120783119957119945 119886119899119889 119914120784
119957119945 as the
threshold capacities of users 119932120783 119886119899119889 119932120784 respectively the combination of OP
could be offered by
119927119954 = 120783 minus 119928120783119961119928120784 in which 120649119950 = 120784119940119950119957119945
119950 isin ሼ119946 120784ሽ -------------(9)
empty120783 =120649120784
120646(120783+119957+120649120784119957) empty120784 =120649120783
120646119957
119928120783 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ 120782 lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 ------------------------(10)
Case 1empty1 gt empty2 for having the limitation of the allocation of power factor (t)
required to be satisfied (tgt120649120783
120649120783+120649120784+120649120783120649120784) and for this case 119928120784 could be attained as
follows
119928120784 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ
120649120783
120649120783+120649120784+120649120783120649120784lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 --------------(11)
Case 2 empty1 lt empty2 Like case 1 it was stated that the opposite constraint depends
on
t gt 1206491
1206491+1206492+12064911206492 and 1199282 can be evaluated as follows
119928120784 = ൝119942119961119953 ቀ
minusempty120784
120649120783ቁ 120782 lt
120649120783
120649120783+120649120784+120649120783120649120784
120782 119952119957119945119942119955119960119946119956119942 ---------------------(12)
54
Table 31 List of parameters
Parameters Description
N Number of nearer users
M Number of far users
E Eavesdropper
ℎ119909119910 Channel coefficient between 119909119905ℎchannel and 119910119905ℎ users
119889119883119884 The distance among x and y
1198890 Space
120598 An exponent of the path loss
ℒ Attenuation of the received signal
120575119898 the range between the BS and the nodes
1205960 Path loss constant
120572 Path loss exponent
1199041 1199042 Unit of power signals received by users 1198801 and 1198802
T Power allocation factor for the adjacent user
ℎ1119886119899119889ℎ2 Channel coefficient of 1198801 and 1198802with the fading of small
scale
11989911198861198991198891198992 Gaussian noise variance
1198730 Zero mean for Gaussian noise
120588 Signal to noise ratio
119878119868119873119877119898119899
Signal to interference noise ratio of users n and m channels
55
120591119898 Exponential distribution parameters
1198750 Pair of OP
1198781198741198751 119878119874119875(1198801)
120573 The permissible SOP threshold
Table 31 depicts the list of parameters used in the proposed methodology which
are useful for assigning and the values are assigned based on the parameters given
for the experimental evaluation as well This chapter concludes with the basic and
the actual flow of the proposed method to know more about the work in the
simulation process
332 Pseudo-code for the proposed algorithm
Algorithm I
Step 1 Estimate Rayleigh distribution
119862119873(0 120575119898minus120572 2Τ
1205961199001 2Τ
) where
120633119950 is the distance between nodes 119932119950 and the BS
120630 is the path-loss exponent and
120654119952 is the path-loss constant
Step 2 The BS broadcasts the superimposed mixture and input signal as follows
119909119905 = ξ1199051199041 + ξ1 minus 1199051199042
Where 119956120783 and 119956120784 are the unit power signals received by users 119932120783 and 119932120784
respectively 119957 is the Power allocation coefficient for the near user
Step 3 The received signal is as follows
1199031 = ℎ1119909119905ξ119875 + 1198991
1199032 = ℎ2119909119905ξ119875 + 1198992 where
56
119945120783 and 119945120784 are the channel gain associated with the
small-scale fading from the BS to users 119932120783 and 119932120784 respectively
1199511 and 1199512 are the additive white Gaussian noise with zero mean and variance
119925120782
Step 4 the BS transmit signal-to-noise ratio (SNR)
120646 = 119927119925120782
Step 5 Signal-to-Interference-plus-Noise-Ratio (SINR) for the two users 119932120783
decodes the signal of the weak user first then decodes its own signal after using
SIC 119932120784 is an untrusted user and tries to decode the near user message after
decoding its own message using SIC
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588ൗ and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ2ȁ2+1120588ൗ and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2
119879119900119905119886119897119904119894119899119903 = ሼ11987811986811987311987721 1198781198681198731198771
1 11987811986811987311987722 1198781198681198731198771
2ሽ
where 119930119920119925119929119950119951
is the signal-to-interference-plus-noise-ratio (SINR)
of user 119950th decoded by 119932119951 for 119898 119899120598ሼ119894 2ሽ and ȁ119945119950ȁ2 is the
channels gain of 119932119950
Algorithm II
Partially observable Markov decision process
Step 1 Prediction of the maximum capacity of channel with respect to the data rate
119955119943 = 119877(119878119909119863)
S is denoted as states
Let D be the channel characteristics which are considering here as actions
Reward function R
Step 2 The agent receives an observation 119900120598120118which depends on the new state of
the environment 119930prime and on the just taken action 119941 with probability
119926(119952ȁ119956prime 119941)
Step 3 Reward earned at time t is expressed as
57
119903119891119905 = 119877(119878119909119863)119905
Step 4 reward function on belief states
119919 is the belief states over POMDP states
119919119943 is the belief state transition function
119955119943 = 119877(119867119909119863)
Step 5 The reward function is updated based on the belief MDP the agent only
cares about which action will yield the largest expected immediate reward ie the
maximum capacity channel
119861119891 ቀℎ 119889 ℎprimeቁ = 119875119903 (
119900120598120118
ℎprimeȁℎ 119889 119900) 119875119903(119900ȁ119889 ℎ) 119861119891
119875119903(ℎprimeȁℎ 119889 119900) = ቄ1119894119891119905ℎ119890119887119890119897119894119890119891119906119901119889119886119905119890119908119894119905ℎ119886119903119892119906119898119890119899119905119904ℎ 119889 119900119903119890119905119906119903119899119904ℎprime
0119900119905ℎ119890119903119908119894119904119890
119903119891(ℎ 119889) = σ ℎ(119904)119877(119904 119889)119904isin119878
34 SUMMARY
The NOMA-UAV communication framework has been proposed in this research
work and the Physical Layer security aspect has been focused on for optimization
The PLS performance metrics selected are SOP amp Pair OP in the proposed system
model The POMDP framework is general enough to model a variety of real-world
sequential decision-making problems Applications include robot navigation
problems machine maintenance and planning under uncertainty in general Here
we have adopted the User pairing POMDP algorithm for resource allocation in two
users amp multi-user NOMA-UAV communication networks The proposed study has
been evaluated using performance measures by varying distances of trusted amp
untrusted users from the base station as well as for varying SINR conditions The
simulation results and outcomes are discussed in a further chapter
58
CHAPTER 4
RESULT AND DISCUSSION
41 PERFORMANCE MEASURES OF SECURED NOMA-
UAV COMMUNICATION MODEL
Drones or UAV-based communication technology has been thoroughly studied and
adopted by the 3GPP standard UAV systems have been envisaged to form an
integral part of future wireless communication applications due to their dynamic
flexible and flying nature Due to their ability to reach higher altitudes they usually
have dominant LOS channels with the ground nodes This capability can be used to
provide confidentiality to the legitimate receivers against the eavesdroppers This
can be done by deploying UAVs to launch more effective jamming signal attacks
to terrestrial eavesdroppers The conventional cooperative jamming schemes make
an assumption that the locations of terrestrial jammers are fixed which might
compromise the secrecy of the system if the jammers are located far away from the
eavesdroppers and is also not practical as it makes an assumption of perfect CSI of
the jammer to eavesdropper channel
Here in the proposed scenario of the NOMA-UAV communication network two
key PHY layer security metrics SOP amp Pair Outage Probability have been jointly
optimized for a more effective power allocation factor for NOMA cellular
architecture The varying channel characteristics have been analyzed to achieve the
desired SOP with the constrained threshold minimum target secrecy rate for the
two-user scenario POMDP Algorithm iteratively provides the optimized SINR that
has been used to keep trusted users in pair with the untrusted user with minimum
achievable outage probability
The proposed NOMA-UAV System model has been simulated in MATLAB 2019b
version with mainly Communications System Toolbox Optimization Toolbox RF
Toolbox Signal Processing Toolbox Statistics and Machine Learning Toolbox
The simulation has been carried out for two-user pair to achieve desired secrecy
target rate and feasible pairing between trusted user amp untrusted user(eves-dropper)
59
The optimal-outage performance of minimized pair OP subjected to SOP constraint
has been solved by both dynamic programming optimization and POMDP
optimization approaches
The simulation of the proposed framework for the UAV-NOMA communication
network has been carried out and discussed in two parts two user models and a
multi-user model as below mentioned discussion The base station is deployed at
the center of a cell of radius 1000 m There are two users in the system under
consideration The channel between two nodes in the system suffers both the small-
scale fading and path loss effect Small-scale fading follows the exponential
distribution with the mean value 1 The noise signal of all channels has a Gaussian
distribution with 0 mean and variance 1 The path loss exponent α and the path loss
constant PLo are set to 2 and 01 respectively We assume a normalized bandwidth
of 1 Hz The SOP constraint threshold is assumed 01 and the target secrecy rate is
001 The power allocation coefficient is 015 and the BS transmitted SINR is
assumed 15dB for the proposed model As per the NOMA transmission scheme
SINR has been obtained for User 1 amp User 2 both for SIC decoding POMDP
algorithm optimally tunes the SINR value for User 1 amp User 2 that is considered to
select optimal power allocation coefficient for both trusted and untrusted users with
respective SOP of User1
42 Numerical results and Discussion
Table 41 Simulation Parameters
Parameters Values
Untrusted user Distance (d2) 200-1000 (300 700)
BS transmit signal-to-noise ratio (SNR) (120588) in dB 15
Sop constraint constant threshold (β) 01
Power allocation factor (t) 015
Trusted User distance (d1) 2-
60
Cell Radius (rd) 1000 meters
Path loss exponent (α) 2
Path loss constant (PLo) 01
Normalized bandwidth in Hz 1
Target secrecy rate (Rs) 001
No of Bits 100
Pair Outage Probability (P0) 05250
SINR 5319 15305 5162
10247
421 Feasible amp Infeasible pairing of trusted amp Untrusted users
In this section the CSI value broadcasted by Base Station is assumed 15 dB initially
and for varying channel conditions various SINR values of 120646 = minus20 minus10 20 dB
is described with target secrecy rate 0005 and 001 for power allocation coefficient
015 and User 1 distance at 200m is shown in the Figure 41 below
Figure 41 Impact on Sop with increase distance between BS and user U2
61
Varying target secrecy rate threshold from 0005 to 001 the obtained result in
Figure 42 revealed that the 1199321 is a gradually reducing function for the distance of
untrusted user d2 that implies that the increasing value of d2 leads to the
improvement of the SOP of 1198801
Figure42 Impact on Sop with increase distance between BS and user U2
Since the offered constant threshold 120656 in SOP limit1199322 which should be located at
a larger space when compared with a value of threshold to attain the SOP of 1199321
apart from that it is expected the high target secrecy rate maximizes the SOP of 1199321
Here in below figure the power allocation coefficient has been varied from 0 to 1
with threshold value of t and the desired t_sop for feasible pairing
Figure 43 Feasible pairing t Vs pair OP
62
Pair OP in case of rising 1199322 untrusted user in d2 for different BS transfer the SNR
where t= 015 and d1=200mThe infeasible pairing of SOP (1199321) and the OP pair
by the enhanced allocation of the power (t) d1 (200m) d2 (300m) 120646 = 15 dB and
120656 = 0
Figure 44 shows the identical plotting of data by adjusting the unauthenticated
level of the user through converting it to a BS closer distance (d2=300m) Accuracy
is compared and checked with the full spectrum of numerical simulations The
result has shown that the effectiveness is based on a comparative study of the two
consumers of the BS
Figure 44 Infeasible pairing t Vs pair OP
422 The Secrecy Outage Probability amp Pair Outage Probability
Feasible paring in the SOP of pair OP and 1199321 with the improved power allocation
factor t in which d2=700m d1=200m 120646 = 15119889119861 and The result described that
the OP and SOP of the user 1199321 with increased for two various distances of the 1199322
untrusted user The simulation result approves the convex nature 120656 = 0 1of the OP
and the SOP is sequentially decreased depending on t Generally when it enhances
the power owed to the weak user text reduces that develop the ability of 1198802 for
discerning the superior positioned signals therefore enhancing the SOP of 1198801
63
Figure 45 Secrecy outage probability
Figure 46 Pair outage probability
423 SNR versus Strictly Positive Secrecy Rate
Figure 47 proved that the potential for confidentiality is superior to the existing
techniques The proposed application for pre-coding improves the efficiency of the
device The transmission power of the system is the power needed for the
transmission of particular data
64
Figure 47 SNR versus Strictly positive secrecy rate
If there is a growth in the number of users there is a risk of inference in the
transmission of data and thus the reliability of the data rate may be affected Based
on these cases the efficiency of the antenna power to be withheld and occupy the
data determined
424 Power radiated by per MMBs antenna
In the case of multi-users scenario when there are more than two users then the
allocation of an optimized resource block to all users is the key parameter to achieve
desired outage efficiency because strong users require higher SNR for higher data
rates and weak users are allocated minimum threshold SNR for lower data rate
requirements to maintain suitable pairing OP and SOP balance
Figure 48 Power radiated by per MMBs antenna
65
So the POMDP policy optimization has shown better performance over the
dynamic programming approach particularly when more users are active (a greater
number of antennas as in Figure 48 the overall radiated power per BS antenna in
downlink has been considerably reduced
43 CONCLUSION AND SCOPE OF FUTURE WORK
431 Conclusion
Starting with LTE (4G) OFDMA has replaced WCDMA with mobile cellular
communications and will also be used during advanced 5G while Non-Orthogonal
Multiple Access (NOMA) has recently been recognized as a groundbreaking PHY
technology in UAV communication NOMA scheme is used in place to increase the
effective use of small resources such as in UAV communication where the data rate
is very low and critical decision making is of utmost importance
The critical need for UAV communication is a secure PHY layer for mission-
critical applications and as NOMA doesnrsquot promise high security the proposed
research work has been carried out to enhance the insecurities of NOMA-UAV
communication In this proposed research work the probabilities of confidential
outage (SOP) and OP were investigated in the two-user NOMA system Here BS is
required to pair a trusted or permissible user with other untrusted users due to the
unequal distribution of untrusted and trusted users in the cell The SIC is then
applied to the receiver side intended for decoding the message signals The Pair OP
of both users has been analyzed for varying Target Secrecy Rate (Rs) of the trusted
user U1 which provides constraint threshold of the SOP of U1
By varying the distance of Untrusted users from BS the optimal distance and power
allocation factor for the feasible pairing of trusted and untrusted users without
compromising the secrecy outage probability of U1 has been achieved in simulation
results
POMDP has provided the optimal power allocation as a resource allocation
algorithm in the dynamically changing environment of two user NOMA cases
where the distance between BS and untrusted user varies significantly The
performance of secure NOMA-UAV is affected critically by (SOP of User 1) which
66
should be optimally selected to maintain the proposed Pair OP between both users
and the simulation results have supported this optimal outage performance Thus
NOMA-UAV architecture has the potential of providing a secure PHY layer for
mission-critical applications by opting for suitable decision-making resource
algorithm POMDP
431 Scope of Future Work
Furthermore the multiuser scenario with the increased number of Untrusted users
can be analytically verified and simulated in the same direction for NOMA-UAV
communication to improve transmission security and reliability In addition more
adaptive and efficient Resource allocation algorithms for NOMA-UAV networks
with secured performance in real-time applications should be investigated
1
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Uddin M A Mansour A Jeune D L Ayaz M amp Aggoune E-H M (2018)
UAV-assisted dynamic clustering of wireless sensor networks for crop health
monitoring Sensors 18(2) 555
Ullah Z Al-Turjman F Moatasim U Mostarda L amp Gagliardi R (2020)
UAVs joint optimization problems and machine learning to improve the 5G and
Beyond communication Computer Networks 107478
Vaezi M Baduge G A A Liu Y Arafa A Fang F amp Ding Z (2019) The
interplay between NOMA and other emerging technologies A survey IEEE
Transactions on Cognitive Communications and Networking 5(4) 900-919
9
Van der Bergh B Chiumento A amp Pollin S (2016) LTE in the sky Trading off
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Communications Magazine 54(5) 44-50
Wang D Xu W Liang W Ding Z amp Li L (2020) Security Provisioning for
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Wireless Communications Letters
Wang H-M Zhang X amp Jiang J-C (2019) UAV-involved wireless physical-
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Wang Q Chen Z Mei W amp Fang J (2017) Improving physical layer security
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310-313
Wang X Feng W Chen Y amp Ge N (2019) UAV swarm-enabled aerial CoMP
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Xiang Z Yang W Cai Y Ding Z Song Y amp Zou Y (2020) NOMA-assisted
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Xie W Liao J Yu C Zhu P amp Liu X (2019) Physical layer security
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11
PUBLICATIONS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495449|P a g e
Migration from 4g LTE to Advanced PHY Techniques for
Unmanned Aerial Vehicle (UAV) Communication
Pankaj Patel PHD StudentGujarat Technological UniversityGujarat India
ABSTRACT
UAV (unmanned aerial vehicles) with their high mobility and low cost have found a wide range of applications
during the past few decades Historically UAVs have been primarily used in the military mainly deployed in
hostile territory to reduce pilot losses With continuous cost reduction and device miniaturization small UAVs
are now more easily accessible to the public hence numerous new applications in the civilian and commercial
domains have emerged For the sake of boosting resilience against faults natural disasters and unexpected
traffic the Unmanned Aerial Vehicle (UAV) assisted wireless communication systems can provide a unique
opportunity to cater for such demands in a timely fashion without relying on the overly-engineered cellular
network However for UAV-assisted communication issues of capacity coverage and energy efficiency are
considered of paramount importance Starting with LTE (4G) Orthogonal Frequency Division Multiple Access
(OFDMA) has replaced WCDMA for cellular mobile communications and it will also be employed in advanced
5G yet Non-orthogonal multiple access (NOMA) has been recently recognized as a promising PHY technique
to significantly improve the spectral efficiency of mobile communication networks In this paper we provide an
overview of UAV-aided wireless communications by introducing the basic networking architecture
highlighting the key design considerations as well as the new opportunities to be exploited
Keywords LTE (4G) Non-orthogonal multiple access (NOMA) Unmanned Aerial Vehicle (UAV) Wireless
communication
----------------------------------------------------------------------------------------------------------------------------- ---------
Date Of Submission 26-04-2019 Date Of Acceptance 06-05-2019
----------------------------------------------------------------------------------------------------------------------------- ----------
I INTRODUCTION The use of unmanned aerial vehicles
(UAVs) will grow rapidly in the next decade These
remotely piloted or preprogrammed aircraft are
envisioned for applications in numerous civil
settings including industrial monitoring scientific
data gathering agriculture public safety and search
and rescue Many other applications - presently
unforeseen - will inevitably also arise These
vehicles also known as the unfortunate misnomer of
drones must be integrated into the national
airspace system and into the airspace worldwide A
natural concern in the use of UAV is safety and this
has direct implications for the control and non-
payload communication systems that must be used
to operate it efficiently Similarly navigation and
surveillance functions must be made more reliable
and more accurate Because of these factors many
UAV research development testing and
standardization efforts are underway by
governments industries and academia Despite the
fact that piloted civil aircraft have been flying safely
for decades UAV presents distinct new challenges
in the form of different flight profiles eg low-
elevation flights and more high-dynamic maneuvers
wider required bandwidths eg for video and
different ground site characteristics such as locations
in cluttered areas and lower elevation antennas
In this paper first the evolution of radio
technologies considered in UAV wireless
communication is reviewed in literature survey and
the significant work in the area is highlighted along
with the newest challenges The reminder of this
paper is organized as follows
The promising technology NOMA and its
variants are discussed in section three In Section
four the system model and assumptions are
presented and in section five the comparative
analysis of NOMA with existing popular technology
OFDMA (OMA) is given with simulation
persormance analysis At last the work is concluded
in section five
II LITERATURE SURVEY Drones variously known as unmanned
aerial vehicles (UAVs) unmanned aerial systems
(UAS) or remotely piloted aircraft system (RPAS)
are used in several parts of the world for surveying
and aerial mapping disaster management work
monitoring crop production and infrastructure
activities besides commercial photography and
courier delivery The viability of UAV as a
multipurpose research vehiclehas driven great
RESEARCH ARTICLE OPEN ACCESS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495450|P a g e
interest since recent decades[1] The
basictechnology building blocks responsible for the
current advancesinclude airframes propulsion
systems payloadssafety or protection systems
launch and recovery dataprocessor ground control
station navigation and guidanceand autonomous
flight controllers The following briefsurvey is
focused on the area of navigation guidance
andcontrol of UAVs Various control design for
UAVs has beenproposed ranging from linear to
nonlinear synthesis timeinvariant to parameter
varying and conventional PID tointelligent control
approaches The developed controllershave been
implemented for different aerial platforms
airship(blimp) fixed-wing UAV small scale
helicopteruad-rotors and MAV Wireless
communication systems that include unmanned
aerial vehicles promise to provide cost-effective
wireless connectivity for devices without
infrastructure coverage Compared to terrestrial
communications or those based on high-altitude
platforms on-demand wireless systems with low-
altitude UAVs are in general faster to deploy more
flexibly reconfigured and likely to have better
communication channels due to the presence of
short-range line-of-sight links However the
utilization of highly mobile and energy-constrained
UAVs for wireless communications also introduces
many new challenges In India for the regulation
and safety purpose in commercial and survilence
applications the policy guideliens also introduced
as below
Table 1UAV communication Policy Guidelines for
commercial and surveillance purpose
III MIGRATION FROM 4G LTE TO 5G The fruitful deployment of UAV based
communicationsystems for 4G and beyond future
wireless networks is highlyinvolved in finding joint
solutions to challenge of ubiquitousconnectivity with
both a multitude of devices in a spectralefficient way
as well as with energy-efficient transmissionand
operation of the UAV-BS for maximized and
armonizedcoverage and capacity [2][3] It should be
noted that suitableenergy efficiency for the UAV-
assisted ommunication systemachieves paramount
importance in the overall performance ofthe system
Efficient energy consumption results in
enhancedairtime for the communication system
improving bitsJoulesfor a given energy level
Furthermore coverage and capacityof an aerial cell
are attributed to many factors such as
thetransmission power antenna gains UAV
altitude deploymentenvironment and prominently
radio access technology [4]
4G is the fourth generation of broadband
cellular network technology succeeding 3G and
besides the popular techniques in 3G4G ie
TDMAWCDMAOFDMA a new radio access
technology NOMA is also developed by researchers
to be used in communication networks due to its
capability in increasing the system capacity
Recently non-orthogonality based system designs
are developed to be used in communication
networks and have gained significant attention of
researchers Hence multiple access (MA) techniques
can now be fundamentally categorized as orthogonal
multiple access (OMA) and non-orthogonal
multiple access (NOMA) In OMA each user can
exploit orthogonalcommunication resources either
within a specific time slot frequency band or code in
order to avoid multiple access interference The
previous generations of networks have employed
OMA schemes such as frequency division multiple
access (FDMA) of first generation (1G)time
division multiple access (TDMA) of 2G code
division multiple access (CDMA) of 3G and
orthogonal frequency division multiple access
(OFDMA) of 4G
In NOMA multiple userscan utilize non-
orthogonal resources concurrently by yielding a high
spectral efficiency while allowing some degree of
multiple access interference at receivers Recently
NOMA reputations have climbedsharply as a
fundamental solution to the challenges
encompassingthe next generation wireless networks
[5][6]NOMA has been proved to exhibit improved
spectral efficiencybalanced and air access as
compared to OMAtechnologies[6] with the ability
to cater for multipledevices in the same frequency
time or code resource thusproviding efficient access
to massive connected devices Furthermore NOMA
is also instrumental in reducingthe interference by
employing orthogonal resources as inOrthogonal
Frequency Division Multiple Access
(OFDMA)[7][17] or by sharing a single beam
between multiple users forintra-cluster access and
using NOMA for inter-cluster access[18]Current
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
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wwwijeracom DOI 1097909622- 090404495451|P a g e
studies have focused on provisioning Air to
Ground(A2G) communication services mainly
through placement op- timization under various
viewpoints in literature The performance of UAV
based communication systems hasalso been
addressed for the underlaid Device to Device(D2D)
deployment scenario This work assumed
interferenceraised by D2D network nodes without
considering the presenceof terrestrial BS
Additionally there have been a fewstudies
discussing the performance of NOMA for UAV
basedcommunication system[8] A NOMA enabled
fixedwingUAV deployment was proposed in [8] to
support coveragefor ground users situated outside
BS offloaded location
In general NOMA schemes can be
classified into two types power-domain
multiplexing andcode-domain multiplexing In
power-domain multiplexing different users are
allocated[7][8][9][6][5][1][10] differentpower
coefficients according to their channel conditions in
order to achieve a high systemperformance In
particular multiple usersrsquo information signals are
superimposed at the transmitterside At the receiver
side successive interference cancellation (SIC) is
applied for decoding thesignals one by one until the
desired userrsquos signal is obtained providing a good
trade-offbetween the throughput of the system and
the user fairness In code-domain multiplexing
different users are allocated different codes and
multiplexed over the same time-frequencyresources
such as multi-user shared access (MUSA) sparse
code multiple access (SCMA) and low-density
spreading (LDS) In addition to power-domain
multiplexing and codedomain multiplexing there are
other NOMA schemes such as pattern division
multiple access(PDMA) and bit division
multiplexing (BDM) Although code-domain
multiplexinghas a potential to enhance spectral
efficiency it requires a high transmission bandwidth
andis not easily applicable to the current systems
On the other hand power-domain multiplexinghas a
simple implementation as considerable changes are
not required on the existing networksAlso it does
not require additional bandwidth in order to improve
spectral efficiency Inthis paper the prime focusis on
the power-domain NOMAAlthough OMA
techniques can achieve a good system performance
even with simple receiversbecause of no mutual
interference among users in an ideal setting they
still do not have theability to address the emerging
challenges due to the increasing demands in future
networks andbeyond
The superiority of NOMA over OMA can
besummarized as follows
_ Spectral efficiency and throughput In OMA such
as in OFDMA a specific frequencyresource is
assigned to each user even it experiences a good or
bad channel conditionthus the overall system suffers
from low spectral efficiency and throughput In
contrary inNOMA the same frequency resource is
assigned to multiple mobile users with good and
bad channel conditions at the same time Hence the
resource assigned for the weak user isalso used by
the strong user and the interference can be mitigated
through SIC processesat usersrsquo receivers Therefore
the probability of having improved spectral
efficiency and ahigh throughput will be considerably
increased
_ User fairness low latency and massive
connectivity In OMA for example in OFDMAwith
scheduling the user with a good channel condition
has a higher priority to be servedwhile the user with
a bad channel condition has to wait to access which
leads to a fairnessproblem and high latency This
approach cannot support massive connectivity
HoweverNOMA can serve multiple users with
different channel conditions simultaneously
thereforeit can provide improved user fairness lower
latency and higher massive connectivity
_ Compatibility NOMA is also compatible
with the current and future communication
systemssince it does not require significant
modifications on the existing architecture For
exampleNOMA has been included in third
generation partnership project long-term
evolutionadvanced (3GPP LTE Release 13)
Figure 1Pictorial comparison of NOMA Vs OMA
Although NOMA has many features that
may support next generationsit has some limitations
that should be addressed in order to exploit its full
advantage set Thoselimitations can be pointed out
as follows In NOMA since each user requires to
decode thesignals of some users before decoding its
own signal the receiver computational
complexitywill be increased when compared to
OMA leading to a longer delay Moreover
informationof channel gains of all users should be
fed back to the base station (BS) but this results in
asignificant channel state information (CSI)
feedback overhead Furthermore if any errors
occurduring SIC processes at any user then the error
probability of successive decoding will beincreased
As a result the number of users should be reduced to
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495452|P a g e
avoid such error propagationAnother reason for
restricting the number of users is that considerable
channel gain differencesamong users with different
channel conditions are needed to have a better
network performance
IV NOMA UPLINK AND DOWNLINK
SCENERIO SIMULATION ANALYSIS In this section an overview of NOMA in
downlink and uplink networks is introduced
throughsignal-to-interference-and-noise ratio (SINR)
and sum rate analyses Then high signal-to-
noiseratio (SNR) analysis has been conducted in
order to compare the performances of OMA
andNOMA techniques[10]
A Downlink NOMA Network
At the transmitter side of downlink NOMA
network as shown in Fig 2 the BS transmits
thecombined signal which is a superposition of the
desired signals of multiple users with different
allocated power coefficients to all mobile users At
the receiver of each user SIC process isassumed to
be performed successively until userrsquos signal is
recovered Power coefficients ofusers are allocated
according to their channel conditions in an inversely
proportional mannerThe user with a bad channel
condition is allocated higher transmission power
than the one which has a good channel condition
Thus since the user with the highest transmission
power considers the signals of other users as noise
and recovers its signal immediately without
performing anySIC process However other users
need to perform SIC processes In SIC each userrsquos
receiverfirst detects the signals that are stronger than
its own desired signal Next those signals
aresubtracted from the received signal and this
process continues until the related userrsquos own signal
is determined Finally each user decodes its own
signal by treating other users with lower
powercoefficients as noise The transmitted signal at
the BS can be written as
s = aiPsxi
L
i=1
where xi is the information of user i (Ui)
with unit energy Ps is the transmission power atthe
BS and ai is the power coefficient allocated for user
i subjected to ai = 1Li=1 and a1gea2gehellip geaL since
without loss of generality the channel gains are
assumed to be ordered as h1 2 le h2 2 le⋯ hL 2 where hL is the channel coefficient of Lth
user based on NOMAconcept The received signal
at lth user can be expressed as follows
y1 = hls + nl = hl aiPsxi + nlL
i=1
where nlis zero mean complex additive Gaussian
noise with a variance of σ2
(1) SINR analysis By using (2) the instantaneous
SINR of the lth user to detect the jth user jle l
with jne L can be written as
SINRl = alγ hl 2
γ hl 2 aiLi=l+1 + 1
Where γ = Psσ2 denotes the SNR
(2) Sum rate analysis After finding the SINR
expressions of downlink NOMA the sumrate
analysis can easily be done The downlink
NOMA achievable data rate of lth user can
beexpressed as
RlNOMA-d
= log2 1 + SINRl = log2(1 +alγhl2γhl2 i=l+1Lai+1
B Uplink NOMA Network
In uplink NOMA network as depicted in
Fig 3 each mobile user transmits its signal to the
BS At the BS SIC iterations are carried out in order
to detect the signals of mobile users By assuming
that downlink and uplink channels are reciprocal and
the BS transmits power allocation coefficients to
mobile users the received signal at the BS for
synchronous uplink NOMA can be expressed as
r = hi aiPxi + n
L
i=1
where hi is the channel coefficient of the ith
user Pxi is the maximum transmission power
assumed to be common for all users and n is zero
mean complex additive Gaussian noise with a
variance of σ2
Figure 2Downlink NOMA network
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495453|P a g e
Figure 3 Uplink NOMA network
1) SINR analysis The BS decodes the signals of
users orderly according to power coefficientsof
users and then the SINR for lth user l ne 1 can
be given by
SINRl =alγ hl 2
γ ai hi 2 + 1lminus1i=1
where γ =P
σ2
2) Sum rate analysis The sum rate of uplink
NOMA when γ minus infincan be written as
Rsum NOMA-u asymp log2(γ hl 2L
l=1
C Comparing NOMA and OMA
The achievable data rate of the lth user of OMA for
both uplink and downlink can be expressed
RsumOMA = αl log2(1 +
βlγ hl 2
αl)L
l=1
For the sake of simplicity sum rates of
uplink NOMA and OMA can be compared for
twousers Then using both the sum rate of uplink
NOMA and OMA at high SNR can beexpressed
respectively as
RsumNOMAasymp log2 γ h1 2 + γ h2 2
Here we notice ROMA
sumle RNOMA
sum
Fig shows that NOMA outperforms OMA in terms
of sum rate in both downlink and uplinkof two
user networks
V SIMULATION RESULTS
The Comparative analysis of modelling
Downlink and Uplink NOMA in comparison with
OMA is simulated and findings are presented that
shows superiority of NOMA over OMA with better
spectral efficiency for simulation parameters taken
as power allocation coefficients a1=06 a2=04 and
channel responses h1 2
=0 DB h22=20 DB
parameters
Figure 4NOMA UPLINK
Figure 5 NOMA DOWNLINK
VI CONCLUSION This paper investigated an account of
NOMArsquos applicability for UAV-assisted
communication systems NOMA schemes are
proposed to improve the efficient usage of limited
network sources OMA based approaches that use
time frequency or code domain in an orthogonal
manner cannot effectively utilize radio resources
limiting the number of users that can be served
simultaneously In order to overcome such
drawbacks and to increase the multiple access
efficiency NOMA technique has been recently
proposed Accordingly users are separated in the
power domain Such a power domain based multiple
access scheme provides effective throughput
improvements depending on the channel conditions
The crucial need of UAV communication of
optimum utilization of available licensed spectrum
bandwidth is considered here and simulation results
taken presented that NOMA performs better than
OMA while fulfilling individual user-rate constraint
for both users The research work can be further
carried out investigating joint power and phase
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495454|P a g e
allocation of UAV nodes deployment for efficient
operations
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Non-Orthogonal Multiple Access for Unmanned
Aerial Vehicle Assisted Communication in IEEE
access 2018
[2] M Mozaffari Drone small cells in the clouds
Design deployment and performance analysis in
IEEE Global Communications Conference 2015
[3] R Z a T J L Y Zeng Wireless
communications with unmanned aerial vehicles
opportunities and challenges in IEEE
communication magazine 2016
[4] I B-Y a H Yanikomeroglu The new frontier in
ran heterogeneity Multi-tier drone-cells IEEE
Communications Magazine pp 48-55 2016
[5] P K S a D I Kim Uav-enabled downlink
wireless system with NOMA access in IEEE
Globecom Workshops Dec 2017
[6] P Xu and K Cumanan Optimal power allocation
scheme for nonorthogonal multiple access with
fairness in IEEE Journal on Selected Areas in
Communications oct 2017
[7] E H a D I K S Ali Non-orthogonal multiple
access (noma) for downlink multiuser mimo
systems User clustering beamforming and power
allocation in IEEE Access 2017
[8] W S M B a M D M Mozaffari Unmanned
aerial vehicle with underlaid device-to-device
communications Performance tradeoffs in IEEE
Transactions on Wireless Communications June
2016
[9] Z D X D a R Z Z Chen An optimization
perspective of the superiority of noma compared to
conventional oma in IEEE Transactions on
Signal Processing Oct 2017
[10] M T Mahmoud Aldababsa1 and S G G K 2 A
Tutorial on Non-Orthogonal Multiple Access
2017
[11] X L Z J W a K J R L Zhu Han Delay
Sensitive Scheduling Schemes for Heterogeneous
QoS over Wireless Networks IEEE
TRANSACTIONS ON WIRELESS
COMMUNICATIONS VOL 6 NO 2
FEBRUARY 2007 vol 6 no 2 2007
[12] Z J W a K J R L Z Han A resource
allocation framework with credit system and user
autonomy over heterogeneous wireless networks
in IEEE Global Telecommunications Conference
2003
[13] N B S a P S S Chen Heterogeneous delay
tolerant task scheduling and energy management in
the smart grid with renewable energy IEEE
Journal of Selected Areas in Communications vol
31 no 07 pp 1258-1267 july 2013
[14] H L Z C a Z H Y Hu Scheduling strategy for
multimedia IEEE Transactions on Vehicular
Technology July 2016
[15] P F a K B L Y Dong High-speed railway
wireless communications efficiency vs fairness
IEEE Transactions on Vehicular Technology vol
63 no 2 pp 925-930 march 2014
[16] T R a Z H Z Chang Queueing game for
spectrum access in cognitive radio networks
IEEE Communications Letters vol 19 no 11 pp
2017-2020 June 2015
[17] Z C L T R a Z H F I Yun Hu Service
Provisioning and User Association for
Heterogeneous Wireless Railway Networks IEEE
Transactions on Communications 2017
[18] H S W Tianti Chen Optimal Scheduling for
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4112 september 2015
Pankaj Patel Migration from 4g LTE to Advanced PHY Techniques for Unmanned Aerial
Vehicle Communication International Journal of Engineering Research and Applications
(IJERA) Vol 09 No04 2019 pp 49-54
INTERNATIONAL JOURNAL OF SCIENTIFIC amp TECHNOLOGY RESEARCH VOLUME 9 ISSUE 04 APRIL 2020 ISSN 2277-8616
2528
IJSTRcopy2020
wwwijstrorg
Improving Of Physical Layer Insecurity Of The
Non Orthogonal Multiple Access System
Pankaj M Patel Prof Dr Chetan B Bhatt
Abstract The key aspect of the NOMA (power domain non orthogonal) is the user possibility for decoding the messages belonging to another pair users
on similar resources The method interprets a security threat especially in the case where the base station serves the users with various security
clearance or untrusted users The main aspect of NOMA is to serve the multiple users upon the similar radio resources at the minimal inter user
interference expense The system not only permits the serving of particular users with high efficient bandwidth but also permits the scheduling more type
of users than the timely available users In this study we investigated the secrecy outage probability (SOP) and OP in the both two user and multi user
NOMA system where the BS is supposed to pair a trusted or legitimate user with other untrusted users because of the un even distribution of the
untrusted and trusted users in the cell SIC the successive interference cancellation was then implemented at the receiver side for decoding the
message signals With the application of NOMA concept the study investigated the pair outage behavior under the SOP constraints on the trusted users
In specific the SOP and OP of the concerned U1 were obtained in the closed type of expressions The study also provided the understanding the
possibility of obtaining an optimal outage efficiency for pairing under the SOP constraints With certain numerical simulations the study verified the
effectiveness of the analytical derivations with respect to various scenarios
Index Terms NOMA Secrecy outage Probability Successive Interference Cancellation bandwidth channel state information etc
mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash
1 INTRODUCTION The physical layer security and non-orthogonal multiple
access was regarded as the encouraging techniques for the
processing of wireless communication network systems Today
the combination of the two significant communication methods
was studied to guarantee a spectral efficient and secure
wireless transmission Most of the prevailing works
predominantly concentrated on the optimization and efficiency
of the PLS in the existence of untrusted relay nodes and
external eavesdroppers(Arafa et al 2019a)But there occurs a
gap in the theoretical studies to describe the ease of obtaining
the enhanced efficiency in the existence of untrusted users
Recently the network traffic amount have greatly enhanced
particularly with the updated growth in IoT applications in
future To rectify the huge traffic demand upcoming wireless
networks must deliver a best spectral effectiveness and large
connectivity (Sun et al 2018) NOMA is regarded as the best
technology in which various NOMA technique exhibit similar
concept of providing several users at the similar frequency and
time The famous NOMA types are code domain and power
domain that provided enhanced efficiency when compared
with the existing techniques The paper adopted the power
domain on the basis of super position coding (transmitter side)
at the SIC (receiver side) Hence the users could possess the
key for the messages of other users and thereby utilize SIC for
removing the interference (Cao et al 2019) (Zhao et al
2018) Hence various NOMA methods was proposed for
allowing the adjacent users to perform as a relay for improving
the efficiency of the weak users through the resending of
decoded data in a next time slot The weak user could utilize
the MRC technique to integrate the information achieved in
different time slots In addition obtaining a secured
communication is a crucial problem over the vulnerable
wireless networks to security threats mainly because of the
broadcasted transmission nature
The study investigated the secrecy performance and outage
with the untrusted user(Furqan et al 2019) The main aspect
of the study is to analyze the feasibility of achieving the OP of
the pair under a trusted user Because of the decoding facility
and spectrum sharing of SIC the untrusted user could perform
as a eavesdropper
Figure 1 Representation of Base station
Figure 1 depicts the representation of base station The main
aim of the proposed system defined as
bull To investigate the outage probability of the proposed
system
bull To investigate the SOP of the proposed system
bull To derive the accurate expression of the outage
probability for all kind of scenarios and closed form of
expressions for few special cases and verifying them
numerically for yielding a better outage efficiency
2 RELATED WORKS This section describes the different existing techniques and
methods related as our proposed system (Cao et al
2019)suggested two kinds of relay selection process denoted
as AF (amplify and forward) and DF (decode and forward) on
the basis of AORS and DORS for achieving secure and
reliable NOMA systems under the untrusted users The study
derived the accurate and asymptotic closed form of the SOP
expressions and the PSCP obtained by the two methods and
investigated the optimized feature of the two methods The
____________________________________
bull PANKAJ M PATEL is currently pursuing PHD program in Electronics
amp Communication in Gujarat Technological University E-mail
pankajmphd24gmailcom
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complete analysis and the simulation results represented that
both the AORS and DORS characteristically outperformed the
benchmark system apart from obtaining the similar SOP and
the required PSCP at very high Signal to noise ratio (Zhang et
al 2018)Investigated the power allocation and joint subcarrier
issue for NOMA ndashAF two-way relay networks with restrictions
The study focused to optimize the obtainable secrecy
efficiency by designing jointly the SC task power allocation
and user pair scheduling The paper suggested a SCAS-1
technique by assuming the appropriate information about the
channel state information in the relay station followed by the
formulation of SCAS-2The secured power allocation issue is
structured as a convex programming issue and then resolved
by in-depth point techniques The results of simulation
explained that the efficiency of the suggested SSPA algorithms
with and without CJ respectively (Arafa et al
2019b)Considered a downlink system where the base station
is connecting with two appropriate users in two various
scenarios in the unsecured environments which are the
presence of the eavesdropper and untrusted relay
communication In the first process several trusted
cooperative relays is engaged for assisting with the base
station transmission and protect the corresponding signals
from the eavesdropper Several relay methods are framed and
investigated for the following process which are forward and
decode cooperative jamming and AFFor all the technique
secured beam forming signals were formulated at the relays
for maximizing the obtainable secret rate areas For the next
process with untrusted relay the obtained secrecy rate areas
obtained for two various relay schemes which are AF and CF
under two various operation modes In the first process the
prescribed users will receive the signals from the untrusted
relay and the base station for decoding the messages The
study depicted that the efficient relay scheme is highly
dependent on the parameters of the system especially the
nodal distance and the secrecy rate area (Sun et al
2018)Studied the algorithm for resource allocation for MISO
systems where the full duplex BS serve several half duplex
downlink and uplink users on the similar subcarrier The
allocation of the resource have been optimized for maximizing
the weight system output whereas the leakage of information
was restricted and an artificial noise was induced for granting
secured communication with respect to potential
eavesdroppers The study formulated a novel non-convex
optimization issue by considering the imperfect CSI of the
channels and requirements of QoS of legitimate users The
simulation results stated the efficiency of the optimal algorithm
was related to the suboptimal algorithm Apart from that the
suggested MISO NOMA technique not only guarantee uplink
and downlink communication purpose for security but delivers
a characteristic rate of system secrecy when compared with
the conventional MISO and other two baseline methods
(Dang et al 2017)Analysed the outage efficiency of various
multicarrier relay selection techniques for 2 hop OFDM system
in Poisson relay fields The study concentrated on DF relay
systems with more selection schemes The accurate
expressions for the OP are provided in integrals generally
Apart from that asymptomatic derivatives for OP in the SNR
region in the fixed circle area are predicted for both relay
selection techniques in closed forms Consequently several
significant factors that are linked to the cooperative network
were examined comprising OP ratio of two selection
techniques diversity and subcarrier optimization output In
conclusion a structure to analyze the OP of OFDM with
spatially random relay have been constructed that could be
easily altered for analyzing same case with various forwarding
protocols channel conditions and location distributors (Dang
et al 2018)Proposed a full duplex OFDM ndashD2D system in two
hop network where DF relays help the transmission from DUE
transmitter to DUE receiver The study also investigated the
OP issue by integrating the transmit power within the DUE
relays and transmitter and to deliver a suboptimal solution that
can improve the outage performance The investigations are
validated by Monte Carlo simulations These results described
could furnish an insight into full duplex OFDM system and
guides for the application in the next generation network
(Kokshoorn et al 2016) suggested a robust channel algorithm
for mmWave systems on the basis of novel overlapped pattern
design With the use of finite measurements the study
depicted that this decreased measurements was found ENR of
25 dB to obtain the similar PEEFor the appropriate channel
with quickly altering channel information the price might be
acceptable for improving the speed of estimation The study
also proposed a robust channel estimation algorithm where
the additional calculations are carried out when expecting
more estimation error The study depicted that the channel
could be measured more effectively resulting in noteworthy
gains upto 6 dB when comparing with the existing algorithm
(Ali et al 2016) described the variations in the principles of
downlink and uplink NOMA transmissions in a wireless
system The study formulated a maximization issue in a cell
like the user clustering and power allocations Because of the
integral nature of the formulated programming issue the study
solved the issue in to steps which are grouping of users into
clusters and then to optimize the corresponding power
allocations The study proposed a sub optimal scheme that
exploited the gain variations in NOMA groups and clusters into
multiple and single clusters for enhancing the sum-throughput
The results compared the efficiency of OMA and NOMA in
different network scenarios (Lv et al 2017) investigated a
MCR-NOMA where the multicast user functions as relays to
enhance the efficiency of both secondary and primary
networks On the basis of the available CSI three various
secondary user schedule techniques for processing MCR-
NOMA were depicted For evaluating the system efficiency the
study derived the closed form of expressions of OP and order
of diversity for both the networks It has been described that
more spatial temporal diversity could be obtained by using the
CSI for scheduling of the secondary user (Liu et al 2016)
considered a MIMO ndashNOMA scenario for investigating a
dynamic clustering issue in an logical perspective To resolve
the problem of optimization issue three algorithms named top
down A and B bottom up were suggested for realizing various
complexity tradeoff and worst user throughput The study
noted that the top down B algorithm could obtain a better
tradeoff between throughput and complexity amongst the
applied procedures (Fianu and Davis 2018) investigated
three various rules of allocation and demonstrated the optimal
policy as an available inventory function The study also
provided the country level estimation of requirements that are
not met and the determination of the probability distribution
linked with the total undeserved counties The study have
been done for depicting the policy of allocation with respect to
effectiveness and equity (Hou et al 2018) studied the socio
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graphical impact on the mobile video services and thereby
suggested a CTMDP on the basis of resource allocation
technique by considering social graphs as the constraints
With the use of relative value an optimized policy could be
achieved that aimed at increasing the reward regarding the
average system The simulation depicted that the suggested
CTMDP obtained an increased efficiency against the state of
art methods
3 PROPOSED WORK
Fig 2 Proposed flow depicting the overall mechanism
The proposed(Interference mitigation using POMDP) overall flow
is depicted in the figure 2 After setting up of the base station the
distance between the base station and the user was determined
and if the distance is less than 200 meters it is decided as trusted
users and if it is greater than 200 m it is defined as untrusted
users In case of untrusted users the channel state information is
subjected to POMDP (Partially observable Markov Decision
Process) followed by resource allocation The performance
analysis have been done after the system The work considered
a NOMA oriented cellular setup provided with a base station at
the centre and two users as shown in the figure 2 The adjacent
(near) user possess high level of security clearance that is
required for securing with physical layer from the low
securityuntrusted clearance user (U2) that is located at a faraway
distance from the base station P is defined as the maximum
transmit power level (base station)In this paper it is assumed that
all the network nodes are installed with single antenna and further
all the channels are considered to be identical independently
quasi static with Rayleigh distribution with respect to distribution
119862119873(0 120575 frasl
120596 frasl
) In which 120575 is the distance in-between the BS
and nodes 119880 Here path-loss exponent and path-loss constant is
represented as 120572 and 120596 In addition it is assumed that base
station predicted the user location so that a better CSI is
obtainable at base station that is involved in pairing the users
The base station transmits the superimposed mixture
119909 = radic119905 119904 + radic1 minus 119905 119904
In which 119904 119904 are the unit power signals received by users 119880 and
119880 respectively 119905 is the power
allocation coefficient for the adjacent user
119903 = ℎ 119909 radic119875 + 119899
119903 = ℎ 119909 radic119875 + 119899
where ℎ ℎ - the channel gain linked with the
small-scale fading from the base station to users 119880 and 119880
respectively 119899 and 119899 are the extra white Gaussian noise with
variance and zero mean 1198730 and it is assumed that 120588 = 1198751198730 is
the BS convey signal-to-noise ratio (SNR) In NOMA technique
farther user that possess more power
could decode its own signal by considering the adjacent signal as
a noise without decoding the adjacent user message In the
preceding equation it is assumed that U1 first decode the weak
signal followed by decoding its own signal with SICU2 which is
the untrusted user attempted to decode the near user message
after the decoding of the adjacent user messages after the
process of decoding its own message with SICHence the
following equation have been achieved
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119879119900119905119886119897 = 119878119868119873119877 119878119868119873119877
119878119868119873119877 119878119868119873119877
+
where 119878119868119873119877 represented the signal-to-interference-plus-noise-
ratio of user 119898 that was decoded by 119880 for 119898119899120598119894 2+ and the
channels gain of 119880 denoted by |ℎ |
followed an exponential distribution
with the parameter 120577 = 120596 120575
Problem Formulation
Hence the base station should achieve and serve a better
communication for the users who are susceptible to security
threat from untrusted user the proposed system defined two
kinds of QoS efficiency measures that could be regarded to be
important for framing the issue In specific the study defined a pair
of OP to check the reliability of the QoS satisfaction In general
the pair OP is stated as the probability in which the obtainable
data rates dor the users equal to or greater than the least target
threshold The next metric also called as the SOP is the
probability that the non negative secrecy capacity obtained by the
trusted user is more than the threshold value
The following issue aimed at reducing the pair OP subjected to a
SOP factor for the user U1 that is provided by
min
119875
0 lt 119905 lt 05
119878119874119875 le 120573
in which 119875 119878119874119875 and 120573 are the pair OP SOP(119880 ) and the
permissible SOP threshold
4 PERFORMANCE ANALYSIS
Derivation of the Pair OP
With the use of Shannonrsquos capacity formula and considering
119862 and 119862
as the threshold capacities of users 119880 and
user 119880 respectively the OP of the pair could be provided
by
119875 = 1 minus 119876 119909119876
in which
120591 = 2
119898 120598 119894 2+
120601 =
( )
120601 =
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119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 1 120601 gt 120601
For having 120601 gt 120601 the constraint on
the power allocation factor (t) needs to be satisfied
(119905 gt
) and for this case 119876 could be obtained as
follows
119876 = exp (
)
lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 2 120601 lt 120601
Like case 1 it was stated that opposite constraint on
a as (119905 lt
) and
119876 can be derived as follows
119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
The OP of the NOMA pair
119875 = 1 minus 119891(119905)119896 (119905)
lt 119905 lt
1 minus 119891(119905)119896 (119905) 0 lt 119905 lt
in which
119891(119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
Derivation of SOP of 119880
With Shannonrsquos capacity formula the secrecy rate of
user 119880 was provided by
119878119862 = 119869 minus 119869
119869 = log (1 + 119879119900119905119886119897 (r (1)))
119869 = log (1 + 119879119900119905119886119897 (r (2)))
119878119862 is the non-negative secrecy capacity of 119880 Provided the
secrecy capacity in the SOP of 119880 is
119878119874119875 = 1 minus 120584119890
119860 =
120584 =
119879 - the user 119880 secrecy target rate
Theorem 1
Outage-optimal power allocation factor
119905 = radic
( )
In which 119908 =
119908 =
119911 = 1 + 120591
The minimum power allocation factor (119886 )
119905 =
(
)
The optimal OP of the NOMA pair under the SOP constraint
=
( )
( ( ))119890
( )
That is lt 0whih meant that the U1 (SOP) is a reducing function
Of t that results in the optimal power allocation factor that is
greater than 119905 for the satisfaction of secrecy constraining
factorPartially observable Markov decision process S is
represented as statesLet D is the channel features which is
consider here as actions the conditional transition probability
between states is regarded as T Reward function R is
calculated as the prediction of maximum capacity channel with
respect to data rate r = R(S x D) the agent receives an
observation o ϵ 120118 o isin Ω display style oin Omega that
depended on the new environment state S and on the just
took action d with the probability O(o|s d)
Reward received at time t is conveyed as r = R(S x D)
H is the belief states over POMDP states
119867 is the belief state transition function
119903 = 119877(119867 x 119863) is the reward function on the belief states
119861 (ℎ 119889 ℎ ) = sum Pr ( 120118 ℎ |ℎ 119889 119900) Pr(119900|119889 ℎ)
Pr(h |h d o) =
1 if the belief update with arguments h d o returns h 0 otherwise
The reward function is updated on the basis of the belief MDP
r (h d) = sum h(s) R(s d) isin
the agent focus on the largest expected immediate rewardin
other words the maximum capacity channel The section
analyse the accuracy of the analytical derivations under
various settings
Figure 3 The feasible pairing
The SOP of U1 with the increasing untrusted user U2 and
distance (d2) for several BS transmits Signal to Noise Ratio
at 120588 = minus20minus1020 119889119861is depicted in with a=005 and 01 and
d1=200m is depicted in the figure The results stated that the
U1(SOP) is a gradually reducing function as per d2 that
implies that the increasing value of d2 leads to the
improvement of the SOP of U1 Since the provided constant
threshold ϵ in SOP restraint U2must be situated at a larger
space when compared with threshold value to obtain the SOP
of U1 Apart from that it is normal that the high the target
secrecy rate rises the SOP of U1
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Figure 4 The Secrecy outage probability
Feasible Pairing in th SOP of pair OP and U1 with the
enhanced power allocation factor (a) in which d2 = 700 m d1
= 200 m 120588 = 15 dB and ϵ = 01 The results depicted that the
the pair OP and SOP of user U1 with increased a for two (d2)
various distances of the (U2) untrusted user The results
approve the convex nature of the pair OP and the SOP curve
is gradually decreasing on the basis of a Generally during the
increase in a the power assigned to the weak user message
decreases that minimize the ability of U2 for discriminating the
superior positioned signals thereby improving the SOP of U1
Figure 5 The Pair outage probability
Pair OP in case of rising U2 untrusted user in distance (d2)
for different base station transfer the signal to noise ratio(120588 =
5 15 25 dB) where a = 015 and d1 = 200 m
Figure 6The infeasible pairing of secrecy outage
probability of the pair OP and U1
The infeasible pairing of SOP (U1) and the pair outage
probability with the enhanced allocation of the power ad1(200
m)d2(300 m)120588 = 15dB and ϵ = 0
The figure 6 depicted that the
The figure 6 shows the similar plotting of the data by altering
the untrusted user location by transferring it to a BS closer
distance (d2 = 300 m) It also depicted that the U1 SOP
constraint of is disrupted at a because the SOP is more than ϵ
The accuracy is well-matched and verified with all range of
numerical simulation The results noticed that the efficiency is
based on the comparative locations of the two user with the
base station
Figure 7 The figure 7 depicts that SNR versus strictly
positive secrecy rate
The observed graph proves that the secrecy capacity
outperforms the existing techniques The proposed precoding
application increases the performance of the system The
transmission power of the system is the power required to
transmit a particular data When there is an increase in the
number of users there is the possibility of inference in the data
transmission and hence the efficiency of the data rate may be
affected Depending on these instances the efficiency of the
antenna capacity to withheld and accommodate the data
determined
Figure 8 The power radiated by BS antenna
In the figure 8with respect to the simulation setup the
precoding methods are performed based on the radiated
power per BS antenna is depicted The results observed the
better efficiency of the proposed system The proposed proves
to be better when compared with existing linear precoding
methods in the prescribed three metrics thereby stating that
MRT may be utilized for the the examination of the secrecy
capacity Our proposed technique spends less radiatated
power thereby increasing the overall capacity of the system
5 CONCLUSION The NOMA system decodes the messages of other user pairs
on the similar resources thereby promoting user possibility
The technique interprests a security threat in which the BS
serves the untrusted users The study analysed the SOP and
OP in both multi user and two user NOMA system in which the
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base station pairs the trusted user in closed type of
expressions The proposed (Interference mitigation using
POMDP) also enable the understanding of possibility of
achieving outage optimal efficiency to pair under SOP
constraints The numerical verifications verified the efficiency
of the analytical derivations
6 REFERENCES [1] ALI M S TABASSUM H amp HOSSAIN E 2016
Dynamic user clustering and power allocation for
uplink and downlink non-orthogonal multiple access
(NOMA) systems IEEE access 4 6325-6343
[2] ARAFA A SHIN W VAEZI M amp POOR H V
2019a Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
15 210-222
[3] ARAFA A SHIN W VAEZI M amp POOR H V
2019b Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
[4] CAO K WANG B DING H LI T amp GONG F
2019 Optimal Relay Selection for Secure NOMA
Systems under Untrusted Users IEEE Transactions
on Vehicular Technology
[5] DANG S CHEN G amp COON J P 2018
Multicarrier relay selection for full-duplex relay-
assisted OFDM D2D systems IEEE Transactions on
Vehicular Technology 67 7204-7218
[6] DANG S COON J P amp CHEN G 2017 Outage
performance of two-hop OFDM systems with
spatially random decode-and-forward relays IEEE
Access 5 27514-27524
[7] FIANU S amp DAVIS L B 2018 A Markov decision
process model for equitable distribution of supplies
under uncertainty European Journal of Operational
Research 264 1101-1115
[8] FURQAN H M HAMAMREH J amp ARSLAN H
2019 Physical Layer Security for NOMA
Requirements Merits Challenges and
Recommendations arXiv preprint arXiv190505064
[9] HOU L ZHENG K CHATZIMISIOS P amp FENG Y
2018 A Continuous-Time Markov decision process-
based resource allocation scheme in vehicular cloud
for mobile video services Computer
Communications 118 140-147
[10] KOKSHOORN M CHEN H WANG P LI Y amp
VUCETIC B 2016 Millimeter wave MIMO channel
estimation using overlapped beam patterns and rate
adaptation IEEE Transactions on Signal Processing
65 601-616
[11] LIU Y ELKASHLAN M DING Z amp
KARAGIANNIDIS G K 2016 Fairness of user
clustering in MIMO non-orthogonal multiple access
systems IEEE Communications Letters 20 1465-
1468
[12] LV L CHEN J NI Q amp DING Z 2017 Design of
cooperative non-orthogonal multicast cognitive
multiple access for 5G systems User scheduling and
performance analysis IEEE Transactions on
Communications 65 2641-2656
[13] SUN Y NG D W K ZHU J amp SCHOBER R
2018 Robust and secure resource allocation for full-
duplex MISO multicarrier NOMA systems IEEE
Transactions on Communications 66 4119-4137
[14] ZHANG H YANG N LONG K PAN M
KARAGIANNIDIS G K amp LEUNG V C 2018
Secure communications in NOMA system
Subcarrier assignment and power allocation IEEE
Journal on Selected Areas in Communications 36
1441-1452
[15] ZHAO T LI G ZHANG G amp ZHANG C-X
Security-Enhanced User Pairing for MISO-NOMA
Downlink Transmission 2018 IEEE Global
Communications Conference (GLOBECOM) 2018
IEEE 1-6
i) I further promise to inform any person to whom I may hereafter assign or license my
copyright in my thesis of the rights granted by me to my university in this non-exclusive
license
j) I am aware of and agree to accept the conditions and regulations of a PhD including
all policy matters related to authorship and plagiarism
Signature of the Research Scholar
Name of Research Scholar Pankaj Manubhai Patel Date 17092021
Place Ahmedabad
Signature of Supervisor
Name of Supervisor Dr Chetan B Bhatt Date 17092021
Place Ahmedabad
Seal
i
ABSTRACT
The landscape of future fifth-generation (5G) radio access networks is
expected to seamlessly and ubiquitously connect everything and
support higher traffic volumes densely connected wireless devices and
diversified requirements on reliability latency battery lifetime etc as
opposed to the current fourth-generation (4G) cellular networks
Moreover in unexpected or emergencies (such as disaster relief and
service recovery) the deployment of terrestrial infrastructures is
economically infeasible and challenging due to high operational
expenditure as well as sophisticated and volatile environments To
address such novel issues intelligent heterogeneous architecture by
leveraging unmanned aerial vehicles (UAVs) (or commonly known as
drones) has been considered to be a promising new paradigm To
improve the system performance of UAV communication in 5G
networks physical layer techniques are of much concern as they affect
the applications of UAVs significantly In this research work security
aspects of NOMA-based UAV communication network have been
considered for optimization as physical layer security in a wireless
communication network is not as robust as wired communication due to
fading and varying SNR scenarios Here primarily two usersrsquo models
as the trusted and untrusted user communicating with BS have been
optimized for outage-optimal performance considering pair Outage
probability and Secrecy outage probability as performance metrics The
achieved results are extended to multi-user scenarios also and for the
optimal policymaking dynamic programming and Partially Observable
Markov Decision Process (POMDP) optimization approaches have
ii
been simulated and verified The simulated results have shown that
POMDP has potential consideration as a resource scheduling
optimization technique in the NOMA-UAV communication network for
providing secure and more robust performance
iii
Acknowledgment
Completing a PhD is a tough task that requires hard work and a lot of effort This is
often an overwhelming but also great experience that I would not have been able to
complete without the assistance and support of so many people Thus it is my great
pleasure to thank all those people First of all I would like to thank almighty for giving
me the strength to carry out this task I would like to deeply thank Dr Chetan B Bhatt
my supervisor for his guidance encouragement and support over these years This
research work would not have been possible without his constructive pieces of advice his
systematic guidance and his patient support thought out the duration of my research work
I would like to express my sincere gratitude to Dr Harshal A ALOORKAR and Dr
KIRAN R TRIVEDI Dr Mehul Raval my doctoral progress committee members Their
rigorous style of reviewing and constructive feedback with valuable suggestions of Dr
Prakash Gajjar Mr Hitesh Panchal and Mrs Monali Mandli who spent their valuable
time whenever required for discussing aspects of this work and provided relevant material
as well Mr Parth Modi and Mr Jagadish Patankar to initiate and inspired me a lot to
continue my work Mr Mukesh Sharma who help in maintain documents I am also
thankful to my parents and family members who always stood with me in each critical
situation and supported me endlessly I am thankful to all EC departments of various
polytechnic and degree engineer colleges for their cooperation in every possible means
Lastly I would thank all the people who directly or indirectly helped me during this very
important phase of my life
Pankaj Manubhai Patel
vi
List of Abbreviation
3GPP 3rd Generation Partnership Project
5G Fifth Generation
A2G Air to Ground
AWGN Additive White Gaussian Noise
BDM Bit Division Multiplexing
BS Base Station
BPCU Bits Per Channel Use
CDMA Code Division Multiple Access
CR Cognitive Radio
CSI Channel State Information
CNPC Control and Non-Payload Communications
CRN Cognitive Radio Networks
D2D Device-to-Device
DCP Difference of Concave Programing
DOMP Dynamic Optimization Method of Programming
FR Floating Relay
GSM Global System for Mobile Communications
HLPSL High-Level Protocol Specification Language
ICT Information and Communication Technology
IoT Internet of Things
IRS Intelligent Reflecting Surface
IMT Information Management Technology
vi
LDS Low-Density Spreading
LTE Long Term Evolution
LTE-A Long Term Evolution Advance
MCR Multicast Cognitive Radio
MI Mobile Internet
MIMO Massive Multiple-Input Multiple-Output
mm-Wave millimeter Wave
MTC Machine-Type Communication
MUSA Multi-User Mutual Access
NOMA Non-Orthogonal Multiple Access
OFDMA Orthogonal Frequency Division Multiple Access
OMA Orthogonal Multiple Access
OP Outage Probability
POMDP Partially Observable Markov Decision Process
PLS Physical Layer Security
PDMA Pattern Division Multiplexing Control
PUN Primary User Networks
QoS Quality of Service
RIS Reconfigurable Intelligent Surface
RNRF Random Near-Random Far
Rs Target Secrecy Rate
SAGIN Space-Air-Ground Integrated Networks
SIC Successive Interference Cancellation
STBC Space-Time Block Coding
vi
SBF Secrecy Beam Forming
SCMA Sparse Code Multiple Access
SOP Secrecy Outage Probability
TAS Transmit Antenna Selection
TDMA Time Division Multiple Access
UAVC Unmanned Aerial Vehicle Communication
UMTS Universal Mobile Telecommunication Systems
URLLC Ultra-Reliable Low Latency Communication
vii
List of Figures
Figure Title Page
No
11 Usage of wireless sensor network and UAV in the
hazardous disaster control
6
12 UAV network applications types with security services
architecture
8
13 UAV-assisted heterogeneous network architecture 12
14 Security problems in the UAV 15
15 Comparative analysis of NOMA vrsquos OMA 18
21 Vehicular communication NOMA system 28
22 RS-NOMA against an external eavesdropper 31
31 Downlink NOMA network 44
32 Uplink NOMA network 46
33 Multi-two user architecture of NOMA system 49
34 Flow Diagram of the proposed system 50
35 Near and Far User 51
41 Impact on Sop with increase distance between BS and user U2 60
42 Impact on Sop with increase distance between BS and user U2 61
43 Feasible pairing t Vs pair OP 61
44 Infeasible pairing t Vs pair OP 62
45 Secrecy outage probability 63
46 Pair outage probability 63
47 SNR versus Strictly positive secrecy rate 64
48 Power radiated by per MMBs antenna 64
viii
List of Tables
Table Title Page
No
11 Physical layer hazards and measures in UAV wireless
communication network
13
21 Comparative analysis 33
31 List of parameters59 54
41 Simulation parameters 59
ix
Table of Content
Sr
No
Title Page
No
I Abstract I
II Acknowledgment II
III List of Abbreviation III
IV List of Figures Iv
V List of tables V
1 Introduction 1
11 Modern technology and its needs 1
111 Long term evolution of 4G network 2
112 Migration from 4G LTE to 5G for UAV communication 3
12 UAV assisted communication in heterogenous sensor network 5
121 Introduction to UAV Communication network 7
122 Tyews of UAVs 8
1221 UAVs as flying BSs 8
1222 UAVs as aerial UBs 10
13 Unmanned aerial vehicle for 5G network 11
14 Physical layer insecurity in UAV communication network 12
141 Principles of security 13
15 Non-Orthogonal Multiple Access (NOMA) system secured
communication
16
151 Comparison of NOMA Vs OMA 16
1511 Spectral throughput and efficiency 17
1512 User fairness and higher lately 17
1513 Compatibility 17
16 Problem identification 18
17 Motivation 19
18 Aim and objective of the research 20
19 Thesis organization 21
2 Literature review 23
x
21 Integration of UAV Networks for 5G and B5G communication 23
22 UAV-NOMA in physical layer security enhancement 26
23 Research methodology 38
24 Summary 39
3 System model for NOMA-UAV communication 41
31 NOMA -UAV system secured communication for 5G 41
311 The basic scheme of NOMA 41
312 Downlink of NOMA 44
313 Uplink of NOMA 46
314 Comparison of NOMA and OMA 47
32 PLS performance metrics in NOMA -UAV communication 47
321 SOP and OP - two user and multi-user NOMA system 48
322 System Model 48
323 Partially Observable Markov Decision Process-POMDP 50
324 Problem formulation 52
33 Performance Analysis Improving PLS Insecurity of NOMA
System
53
331 The pair OP calculation 53
332 Pseudo-code for the proposed algorithm 55
34 Summary 57
4 Result and discussion 58
41 Performance measure of secured NOMA-UAV communication
model
58
42 Numerical result and discussion 59
421 Feasible amp Infeasible pairing of trusted amp untrusted
users
60
422 The secrecy outage probability and pair outage
probability
62
423 SNR versus strictly positive secrecy rate 63
424 Power radiated by per MMBs antenna
64
43 Conclusion and scope of future work 65
431 Conclusion 65
432 Future scope 66
xi
5 References 67
8
Publications 78
1
CHAPTER -1
INTRODUCTION
11 Modern technology and its needs
Mobile technology has undergone various generational shifts transforming the
cellular framework into a worldwide set of interconnected networks In recent days
the fifth generation (5G) has delivered voice as well as video streaming It has a
very complex range of networking services for more than nine billion users and also
billions of devices that will be connected (Hu 2016) However 5G offers a new
outlet for reflection It involves a radial network architecture for the installation of
communication-type machines 5G network can also include powerful support
applications with widely varying operating parameters 5G is a blend of network
technologies that have been developed The new 5G technology will be able to
exchange information anywhere every time for the benefit of people enterprise
and society and technical environments using a restricted access bandwidth to
carry data Now it is more than a modern series of technologies and as opposed to
previous generations would entail tremendous infrastructure or machinery
upgrades This technology aims to expand on the advances that telecommunications
systems have already achieved The projected standards of efficiency that
technologies would need to resolve are
bull Five times reduce end-end latency
bull Ten to a hundred times the higher complex rate of user data
bull Battery life is ten times longer
bull 10 to 100 times higher number of connected devices
In this research work the UAV-assisted communication over the 5G network has
been proposed with enhanced physical layer security aspects NOMA has been
proposed as the reference framework architecture for UAV communication as one
of the recent popular 5G techniques Along with the advantage of suitability in UAV
communication network NOMA has the disadvantage of insecurity in the physical
layer Here the migration of Long Term Evolution (LTE) to advanced physical layer
2
security for Unmanned Aerial Vehicle communication (UAV) over 5G network has
been proposed and also improve the insecurity of Non-Orthogonal Multiple Access
(NOMA) System We will discuss in the further chapter the proposed work This
chapter describes the introduction and basic concepts of the 5G networks with
methodology techniques and types It states the problem identification motivation
and further aim and objective of this work
111 Long Term Evolution of 4G Network
LTE is customary for 4G wireless broadband trends that provide improved network
capability and gives mobile device users speed It offers high peak data transform
rates in the range of 100 Mbps and 30 Mbps downstream and upstream
respectively It provides a capacity of scalable bandwidth mitigated latency and
backward compatibility with the previous Global System for Mobile
Communications (GSM) and Universal Mobile Telecommunication Systems
(UMTS) technology
The fourth development of cellular networks (4G) has already been developed to
meet the standards of the 3G and 2G families Every 10th year a new mobile
generation claimed to be familiarized with the first 1G system in 1981 tracked by
the 2G system that went on to roll out in 1992 and 3G launched in 2001 growth in
the year 2002 of 4G networks The actual new revolution began in December 1998
with the 3rd Generation Partnership Project (3GPP) With high-quality video and
images 3G networks are designed for multimedia networking with them Peoples
communication can also be enhanced and connectivity to public and private
network information and resources has improved with higher frequencies and new
flexible communication features third-party device applications
With the start of LTE-Advanced several vital demands and improvements are
beginning to emerge Various importance purposed for LTE-Advanced can be
exemplified as follows (Abed)
bull Provides spectrum output with LTE delivered more than three times
bull Spectrum can help scalable bandwidth and convergence of the spectrum
where it is necessary to use a non-contiguous range
3
bull Provides uplink and downlink spectrum output that varies between
15bpsHz and 30bpsHz
bull The edge throughput must be twice that of the user cell in LTE
bull From idle status to connected status the communication latency scenario is
smaller than 50msec and less than 5msec for direct packet transfer
bull Any users total throughput must be three times that of LTE
bull LTE advancement will provide 3GPP as well as LTE compatibility via inter
networking
bull The mobility conditions that are used in LTE are identical
The latest LTE advanced requirements are not yet included in device
specifications there are high-level purposes Before it is fixed in the specifications
and needs to be tested much effort remains to be approved
112 Migration from 4G LTE to 5G for UAV communication
The productive implementation of a UAV communication network in 4G and the
upcoming wireless network is included in identifying combined solutions to test
the correlation with both multitudes and also energy-efficient transmission Then
the process of the UAV-BS to optimize coverage and power It is stated that the
energy efficiency of the UAV-aided communication system is needed Efficient
energy utilization contributes to increased air time in the contact system and
increased joulesbits at a provided energy level Also aerial cell coverage and
ability may be because of various parameters such as antenna gains transmission
strength radio access technology UAV altitude and deployment environment
4G is the fourth generation of network infrastructure technologies to replace 3G and
in addition to the popular 3G4G methods Code Division Multiple Access
(CDMA) Time Division Multiple Access (TDMA) and Orthogonal Frequency
Division Multiple Access (OFDMA) Researchers are designing the latest Non-
Orthogonal Multiple Access (NOMA) technologies to be used because of their
capability to improve the performance of communication networks Non-
4
orthogonality-based device designs have recently been developed for use in
communication networks and drawn considerable interest from researchers
Henceforth Multiple Access (MA) methods can be sub-divided as OMA and
NOMA Each user may utilize orthogonal communication resources to determine
multiple access interference inside a frequency band code and time slot in OMA
Its methods such as First generation (1G)- FDMA 2G -TDMA 3G -CDMA and
4G - OFDMA have been used in previous network generations In NOMA by
producing a higher spectral efficiency however enabling some amount of multiple
entree intrusion in receivers and multiple users may use non-orthogonal resources
simultaneously Recently the credibility of NOMA as a solution to the problems of
the next generation of wireless networks has been increased Compared with OMA
technologies NOMA has been described to improve spectral quality be well-
adjusted with air connectivity and can provide accommodations for multiple
strategies at the same time of frequency Therefore enabling excellent progress to
massively correlated devices
In particular NOMA also affects mitigating interference by using OFDMA as an
orthogonal method or through offering a standard intra-cluster access beam across
multiple users and inter-cluster access in NOMA Recent studies have concentrated
primarily on the provision of Air to Ground (A2G) connectivity services through
optimization of a different point of view
The output of the UAV-based communication network was discussed in the Device
to Device (D2D) implementation setup The proposed system hypothesized
interference caused through D2D network nodes deprived of acknowledging the
occurrence of global BS Also several studies addressed the efficiency of NOMA
It permitted the deployment of fixed-wing to assist coverage in-ground user located
outer location of offloaded BS
NOMA systems are divided into two categories namely code domain and power
domain multiplexing In the power domain user accounts are allocated to different
power coefficients as per their channel complaint to reach optimal device
efficiency Multiple user signals are applied to the side of the sender Then on the
received signal Successive Interference Cancellation (SIC) is implemented to
decipher signals in sequential order until the predicted signal is achieved offering
5
a good trade-off between efficiency of the system and user fairness Different code
domain multiplexing is Sparse Code Multiple Access (SCMA) Low-Density
Spreading (LDS) and Multi-User Mutual Access (MUSA) Compared to power and
code domain multiplexing there are alternate NOMA techniques such as Bit
Division Multiplexing (BDM) and Pattern Division Multiplexing Control (PDMA)
However this multiplexing is capable of improving the efficacy of spectral It
requires a large transfer of bandwidth which is not appropriate for new methods
But on the other side the power domain has direct execution since there is no need
for significant improvements to the current networks It also does not necessitate
bandwidth to increase spectral efficiency In this chapter the main emphasis
depends on the power domain NOMA While OMA strategies can produce the best
results also with necessary receivers due to no mutual intervention among users in
an optimal situation they cannot even resolve increasing problems due to growing
demands on connectivity growth and even beyond
12 UAV assisted communication in heterogeneous sensor network
Wireless communications had created a golden chance for urban and rural
territories The LTE (Long term evolution) and LTE-A (Long term evolution
Advance) had offered the service (with QoS) for all customers through wireless
The traffic properties in the machine type communications (MTC) and the
accumulation of the MI (Mobile Internet) had made the difficulty of implementing
the cellular communication networks Installing base stations was impractical in the
urban areas due to its cost To overcome this issue the UAV suggested that it
contains the merits of compatibility and high battery life and is affordable Most of
the devices like the sensor nodes and professional cameras had been used in UAV-
assisted networks Here the UAV-assisted floating relay (FR) was launched in the
cellular communication networks UAVs were implemented more with WSN
(wireless sensor networks) The base stations were adopted with the UAV So the
MI and MTC traffic challenges were controlled (Yue Li amp Cai 2017)
UAV-assisted Heterogeneous networks had implemented in vast practical
applications UAV helped heterogeneous networks were applied in the military
department In the military the UAV had examined and surveyed the opposing
6
countryrsquos activities for security The UAV-based heterogeneous networks were
used in the military sectors where a novel authentication scheme was introduced
As The one-to-one communication via WSN was considered as secured
communication WSN had the disadvantage of consuming power The
authentication was implemented in the tool of Automated Validation
of Internet Security Protocols and Applications (AVISPA) in which the expression
had been written in the High-Level Protocol Specification Language (HLPSL)
programming language The authentication had evaluated between the user and the
base station Similarly the authentication between the user and the UAV was
calibrated The citizen and economic safety are predicted and conserved through
reliable communication in the military by obtaining foes exploration information
The faithful secured communication was confirmed using AVISPA (Rashid et al
2019)
Figure 11 Usage of wireless sensor network and UAV in the hazardous
disaster control
The integration of the wireless sensor networks and the unmanned aerial vehicle
UAV was analyzed and applied to manage the natural disaster illustrated in Figure
11 The aircraft can prevent the fire spreading drop sensors the temperature map
and biodiversity map by sensors the wildfire can easily route The wild animals can
7
be tracked and the dynamic data of moving animals can be gathered by WSNs The
biologists can fix the sensor in the animals collar the radiation that positively
affects humans can be observed in affected areas The WSNs help to prevent heart
attack of a person by monitoring heart rate The state of health can be known
through a message alarm using a GPRS system
The cooperative networks of WSN and UAV were implemented in the military
sector for the advantageous feature The UAV was providing good connections
overlapping and overall data rate The conventional UAV method aided sensor
networks concentrated only on the single tasks of monitoring accumulating
information and localization The multi-UAV had not been implemented in the
sensor networks The animal colony perception technique was utilized for
scheduling the resourced and the target assignment Functions of multi-data were
used for localization by the target recognition method (Gu Su et al 2018)
The Physical Layer Security (PLS) was achieved through 5G technologies delicate
coding for the PLS dense MIMO multi-input multi-output mm-Wave frequency
band using heterogeneous sensor networks NOMA and full-duplex mode of
communication IoT and Machine-type communications (MTC) emerged in the 5G
systems (Wu et al 2018)
121 Introduction to UAV communication network
The usage of the UAV will develop more in the next era These pre-programmed
aircraft are intended for applications in several civil settings as well as industrial
visualization agriculture rescue and search and then receiving of scientific data
These devices are called the unsuccessful inaccuracy of drones which must be
incorporated into the system of national airspace as well as worldwide The usage
of UAVs in the neutral form is always secure It has a direct inference for the control
and a payload communication system that is utilized to function effectively
Similarly surveillance and navigation operations must be made more accurate and
consistent Due to these critical factors many kinds of research in a UAV testing
development and standardization difficulties are undergone through industries
education and governments
8
Even though civil aircraft had been operating for many years yet UAV offers new
consequences in terms of various flight profiles For example high dynamic
maneuvers and low elevation flights need bandwidth video and different ground
site characteristics namely clutter locations and elevation antennas which are low
This chapter explains the core topic of the proposed work The migration of LTE
4G towards the advanced one of the physical layers for UAV communication It has
higher mobility and lower expense identified in a broad range of applications
122 Types of UAVs
The UAVs have a two-network application with security services such as UAVs as
Flying Base Stations (BSs) and UAVs as Aerial BSs in the presence of
eavesdroppers
(a) UAVs as Flying BSs (b) UAVs as Aerial mobile UEs
Figure 12 UAV network applications types with security services
architecture
1221 UAVs as flying BSs
The required infrastructure can be destroyed in natural disasters particularly
tsunamis earthquakes and snowstorms and the requisite emergency data traffic
cause both overloading and congestion of neighboring mm-Wave (Zeng et al
2016) A capable explanation is to rapidly introduce low-altitude UAVs as flying
9
BSs in such a network breakdown to improve the communication infrastructure to
mitigate cell congestion or site failure thus creating a small aerial cell
In this situation wireless communications can occur in an ad-hoc manner with
UAVs to UEs UAVs to UAVs As highlighted in Figure-12 (a) and control
stations of UAVs to ground It will increase capability dramatically and enlarge the
target of wireless networks in provisional measures as it is possible to create LoS
communication links among UAVs and UEs supported on the ground Yet form an
operating aerial cell system to monitor ground segments of UEs mobility which is
more stable to minimize sporadic connectivity on the other side
Also this can be expanded to allow several UAVs-BSs to be deployed to increase
the exposure area for supporting a wide range of UEs A network period various
UAVs-BSs is entirely independent A new paradigm was introduced through
collaboration between UAVs-BSs to extend the feasibility for a single UAV from
either a stand-alone active sensor to a wireless network over the next generation
There is a growing concern about the privacy problem in tandem with the brief
introduction of this network Wireless protection is the central issue of the
communication level wherever eavesdropping subsidizes for deliberately listening
to a source of secret information which harms the extensive placement of UAV-
BSs
A UAV-BSs is to mount several antennas in the UAV-BSs the benefits of multi-
antenna innovations geographical degree of freedom that offers an ability for UAV-
BSs to transmit eavesdropping airborne beams
Notice that in UAV systems multi-antenna technology can be technically applied
while directly modifying the separation of the antennas The existing system has
shown that transmitted beam forming models can significantly boost the
confidentiality efficiency of wiretap channels for multiple antenna transmitters
Noise may be inserted with the signal to substantially degrade the acknowledged
SINR at the eavesdroppers to prevent the information overflow
10
1222 UAVs as aerial UEs
This has already been demonstrated by reaping the benefits of Wi-Fi and LTE
technologies through field trials (Van der Bergh et al 2016) UAV-UEs typically
get their tasks for a variety of convincing IoT applications mainly in air freight
services like the google wing project Unlike conventional land base package
delivery but UAV delivery has distinctive merits such as
bull Acceleration of land transport as UAVs are not liable to road jams
bull Connection to areas that are difficult to reach
bull Decreasing the use of capital about workforce and electricity
UAV distribution is significantly dependent on having reliable and secure wireless
communication among UAVs and ground BSs especially if the UAV needs control
outside LoS the UAV-UEs are used which can develop LoS connectivity to cellular
BSs The UAV-UEs on the one hand provides high-speed access to data as it can
fly continuously in either direction On the other hand the installation of UAV-UEs
can lead to significant interference with the ground BSs in the execution of their
missions
A wide-scale installation of UAV-UEs is only feasible for this reason if the issues
of interference management are tackled It is widely known that interference
negatively affects wireless networks As highlighted in Figure-12 (b) indeed aerial
and ground UEs are served through a cellular network with a possible eavesdropper
that tries to intercept the message intended for permissible basic UEs
A cost-effective approach is to be used for coordination among ground BS and
UAVs to enhance secure transmission which is part of the UAVs acting as friendly
transmitters to degrade the wiretapping channels efficiency and thus enhance
secrecy efficiency A UAV acting as a mobile jammer can dramatically and
dynamically change its position as near as possible to the earth eavesdropper and
distribute them by sending the radio signals whereas strong LOS connection
characteristics are a beneficial feature with less earthly fading and shadowing
impairment
11
13 Unmanned Aerial Vehicle for 5G Networks
UAVs have technologically advanced as a revolutionary movement in delivering
pervasive connectivity from either the platforms of the sky as aerial
communication particularly for temporary User Equipment (UEs) (B Li et al
2019) Due to fully controllable UAV flexibility through miniaturization as well as
continuous cost reduction low-altitude UAVs are rapid and flexible designed for
operation and reconfiguration They are probable to have higher Line-of-Sight
(LoS) ties to ground UEs
A broad range of applications like inspection of infrastructure precision farming
and disaster area monitoring is becoming accessible in this aspect Moreover
further projects have also been set up to employ aerial platforms for broadband
access to distant elements such as the Google Loon and the Facebook Drone Project
to mention Highly populated UEs are desperate for broadband wireless
communications with the coming 5G period and network providers are supposed
to maintain numerous networks with high demands for wireless data like
multimedia streaming and also video downloads The relentless growth in the
amount of traffic of mobile networks puts a burden on operators in the form of
higher capital and operational expenditure Deploying small cell networks is an
intuitive alternative to outsource cellular traffic
Although in unforeseen or temporary events as mobile environments are
complicated volatile and heterogeneous the implementation of terrestrial
infrastructures is difficult The accessibility of aerial access points to enable
extensive complex connections is one possible solution However in unforeseen or
temporary events as mobile environments are complicated volatile and
heterogeneous the implementation of terrestrial infrastructures is difficult The
accessibility of aerial access points to enable extensive complex connections is one
possible solution UAV communication performance benefits from the simplicity
of the compact transceiver and progressive control methods that obtain broad
exposure and set up internet networks
12
Figure 13 UAV-assisted heterogeneous network architecture
The above Figure 13 is depicted to build flexibility of the network with enhanced
ability and elasticity It is a good network that offers security endowment This is
due to the transmitting information to UAV communication which is tapped
through ground unauthorized user and is known as an eavesdropper
Here through eavesdropper based on the upper layer cryptographic techniques
wireless communication in contradiction of unauthorized access has been protected
However it is very tough to achieve because of key management as well as more
computational difficulties in developing network architecture PLS affects the
characteristics of intrinsic wireless networks as a fascinating preparation such as
interference noise fading loss collecting signal characteristics in malicious
eavesdroppers and techniques of signal processing
14 Physical Layer Insecurity in UAV communication network
Jamming is either a well-defined WSN attack on a physical layer It disrupts the
radio waves being used by nodes of the network The attacker successively
expresses the denial of the simple MAC protocol over the wireless network The
impressive network can be disrupted at which a single frequency is being used
13
throughout a network (Modares et al 2011) In addition jamming can increase
energy consumption in the node by inserting impudent packets The receiver nodes
will also generate resources when receiving the packets In (Jeon 2006) four
different terms of jamming attacks that an intruder could use to interrupt the
wireless network activity Tampering is yet another physical layer assault
Table 11 Physical layer hazards and measures in UAV wireless
communication network
(Kumar et al 2014)
Hazard Security measures
Jamming Channel blacklisting and hopping
Interference Channel hopping and blacklisting
Tampering Security and key modification
Sybil Physical security of the system
Table 11 describes physical layer hazards and their security measures in WSN
which tampering and jamming are considered as the main attack in the physical
layer in WSN
141 Principles of security
The security requirement of UAV communication network is as follows (Kumar et
al 2014)
Confidentiality Ensure that only the approved sensor nodes could get the contents
of the texts
bull Authentication Ensure that the data is introduced from the sound source
bull Integrity Ensure that every received text has not been modified to be sent
by unauthorized users
14
bull Freshness Make confirm that no old information has been reiterated
bull Availability services are feasible at any time through WSN or by a single
node
The standard attacks of the physical layer are as follows (Sastry et al
2013)
bull Jamming The transmission of the radio signal can interfere only with radio
frequencies used through WSN which is known as jamming As the
capacity grows it may influence more significant portions of the network
by transmitting other radio signals The opponent will use a few nodes to
occupy the entire channel This state is called physical layer jamming which
results in a denial of service In this scenario the opponent will not be
permitted to have any knowledge but will be capable of preventing
communication to any nodes
bull Tampering Often the nodes tampered through an opponent This mode is
called tempering Here the attackers can destroy exchange and
electronically confront nodes to obtain information from counter measures
towards jamming that have been planned as spread as well as frequency
hopping
bull A security mechanism is used in WSN to track avoid and recover from
security attacks A wide range of security schemes can be devised to counter
malicious threats which can be classified as high and low levels
bull Secrecy and Authentication Most network sensor applications need
protection from eavesdropping packet alteration and injection Early
networks are used for connection layer cryptography as this approach offers
the easiest deployment of network cryptographic solutions
bull Privacy Like all other conventional networks the radio networks have also
brought secret issues to allow Initially sensor networks are implemented
for legitimate purposes and can eventually be used unexpectedly
Knowledge of active sensor nodes as well as the acquisition of data is
exceptionally crucial
15
bull Critical launch and trust setup The primary prerequisite for setting up a
network is the development of keys (cryptography) Sensor devices
typically have minimal computing capacity and public cryptographic
primitives are too difficult to adopt Critical establishment and strategies
need to be scaled to network with thousands of nodes
bull Secure routing Routing as well as data forwarding is a problem that
confronts to facilitate communication in networks Regrettably the latest
protocols encounter a variety of security flaws
bull Robustness of communication Does An opponent challenges to interrupt
the operation of the network
Figure 14 Security problems in the UAV
Figure 14 illustrated the security difficulties in a UAV The physical layer security
in the UAV wireless networks was examined The UAV had affected by both active
eavesdropper and passive eavesdropper This paper proposed the trajectory design
and cooperative UAV for constraining the eavesdropper NOMA MIMO mm-
Wave frequency band in UAV would cause better spectral efficiency and security
(Xiaofang Sun et al 2019)
UAV implementation of the 5G communication was considered advantageous The
UAV was assumed as the novel wireless network technique for the territory users
and their base stations The UAV had resulted in high altitude So the UAV had
16
considered a superior line of sight At the same time the possibility of security
problems was raised in a UAV The secrecy in the existence of eavesdropper the
jammer in the ground was performed using the UAV UAV aided territory security
was proposed The UAV was involved in inspecting the eavesdropper and hazard
jammers on the base stations territory UAV had targeted the global position system
spoofing for assisting the authentic users and performed the role of an artificial
eavesdropper for excluding the eavesdropper and jammers in the ground (H-M
Wang et al 2019)
15 Non-Orthogonal Multiple Access (NOMA) System Secured
Communication
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
151 Comparison of NOMA Vs OMA
Comparison of the NOMA and OMA can be discussed as follows
17
1511 Spectral throughput and efficiency
In OMA a resource is allotted to the distinct user whether it is good or bad in a
channel scenario like OFDMA Thus the whole process moves from less
throughput and performance
While the same frequency is allotted to the multiple-use at the same time with good
or bad channel operation in NOMA here the weak user gets the allocated for the
resources which the strong user can also use it And the interference can be reduced
by the SIC process on the receptor side of the user Consequently the probability
with the increased spectral efficiency as well the high throughput will be
maximized
1512 User fairness and higher lately
A user of fair channel complaints has higher precedence to be served in OMA In
contrast a user with a poor channel complaint is to remain activity which causes
the issue of user fairness and higher latency Yet OMA cannot assist colossal
connectivity Whereas NOMA helps multiple users with various channel
procedures and offers increased fairness massive connectivity and lower latency
1513 Compatibility
NOMA has compatibility with the current and upcoming scenario meanwhile no
need for necessary changes to the previous methods As an instance NOMA has
been bought up in the 3G Partnership Project LTE Advanced (3GPP LTE) Though
NOMA contains many characteristics that can assist the upcoming generations and
it has some restrictions that can be explored with its full benefits Those restrictions
are as follows
bull Each user has to decrypt the signals of other users until decrypted their
signal the complexity of the receiver would be strengthened in NOMA as
opposed to OMA which creates a long pause
bull Also data on channel quality for all users should be returned to the BS but
this results in substantial CSI input overhead Furthermore if any issues
arise to any consumer during the SIC process the likelihood of consecutive
decrypting errors will be improved
18
Figure 15 Comparative analysis of NOMA vrsquos OMA
As an outcome the number of users is reduced to ignore the spread of such
debugging Another aim of restricting the number of users is that there must be
substantial variations in channel revenues between users with different channel
grievances to provide network reliability
16 Problem Identification
The NOMA-based architectures main feature is to configure trusted and untrusted
users when more than one eavesdropper is present in the dense setting of todayrsquos
and future sophisticated wireless communication networks This research aims to
examine the security efficiency suggested for mission-critical applications in the
NOMA-based UAV communication network The proposed system underpins two
user NOMA frameworks The possibility of paring both users was explored with
PHY performance measures in mind Outage probability (OP) and Secrecy Outage
Probability (SOP) Dynamic Optimization Method Programming (DP) and Partially
Observable Markov Decision Process (POMDP) optimization have also been
analyzed to explore the feasibility of achieving an outage-optimal output for the
pair under the heavy users secrecy outage restriction The optimized theoretical
findings are applied to the multiuser scenario The identifications were tested
through a computer model in which POMDP has shown substantial progress over
the dynamic optimization method to program
19
17 Motivation
Unmanned aerial vehicle (UAV) wireless communications have experienced an
upsurge of interest in both military and civilian applications due to its high
mobility low cost on-demand deployment and inherent line-of-sight air-to-ground
channels However these benefits also make UAV wireless communication
systems vulnerable to malicious eavesdropping attacks
Despite the promising gains brought by UAVs the open nature of air-to-ground
wireless channels makes secure information transfer a challenging issue
specifically on the one hand information signals transmitted over wireless LoS
channels are likely to be intercepted by some undesired receivers which lead to a
risk of information leakage On the other hand wireless UAV transceivers are
vulnerable to malicious jamming attacks Hence security plays an extremely
important role in UAV wireless communications Unfortunately traditional
encryption techniques require high computational complexity leading to a large
amount of energy consumption which may not be suitable for UAV systems As an
alternative physical layer security is computationally efficient and effective in
safeguarding wireless communication networks via exploiting the inherent
randomness of wireless channels As a result various physical layer techniques
have been proposed in the literature for guaranteeing communication security
NOMA is viewed as a promising technique to provide superior spectral efficiency
by multiplexing information signals at different power levels [13] Hence it is
expected that NOMA can bring additional rate and robustness to enhance the
achievable rate in UAV physical layer security communications Consider a
scenario where a UAV acts as a relay to facilitate data delivery to two receivers
with different security clearance levels within a maximum cruising duration T The
receiver with a lower security clearance level and a higher potential with an
eavesdropper Since it has a strong motivation in intercepting signals intended for
a receiver with a higher security clearance Then when the eavesdropper suffers
from a bad channel condition NOMA is adopted to forward both confidential and
public information simultaneously Otherwise UAV only broadcasts the public
information for security issues The mode selection between NOMA and unicast is
20
chosen based on the results of the proposed resource allocation optimization In
particular for maximizing the spectral efficiency one needs to jointly optimize the
transmission scheme resource allocation and UAVrsquos trajectory However the
coupled optimization variables generally result in non-convex optimization
problems which are difficult to solve optimally As an alternative an iterative
suboptimal algorithm based on successive convex approximation can be employed
to facilitate a computationally efficient joint design We have discussed that the
NOMA scheme always outperforms OMA in all the considered scenarios which
demonstrates the spectral efficiency advantage brought by NOMA in striking a
balance between public data rate and confidential data rate
The main motive of this research is to enhance the inherently insecure PHY layer
of the NOMA-based UAV communication network NOMA-UAV communication
network requires feasible paring between trusted amp untrusted users (attacker) for
cooperative communication mainly in real-time field applications The power
allocation factor need to be optimized as per the trustworthiness of the associated
users (reliable user) and keeping the outage probability minimum for secured and
cooperative communications The pair Outage Probability and the SOP have been
optimized jointly for feasible pairing between BS amp the associated Users
18 Aim and Objective of the Research
The proposed works main objective is to examine the design of a NOMA-based
UAV communication network for enhanced Physical Layer security (PLS)
features Remarkably it is anticipated infrastructures and resources to connect
numerous devices and provide various services Researchers these days
concentrating on ways to design a heterogeneous framework like deployed small
cells air and ground-based deploy multifarious communication methods in 5G
such as millimeter-wave (mm-Wave) device-to-device (D2D) massive multiple-
input multiple-output (MIMO) Cognitive Radio (CR) and so on for improving
spectrum and energy efficiency
As a critical need especially for emergency applications the adoption of NOMA
transmission of UAV communication needs to be improved PLS A new optimal
resource allocation algorithm for some more robust and stable communication in
21
single and multiuser scenarios has been suggested here The PLS in dense
heterogeneous sensor networks has improved by the feasible pairing of trusted and
untrusted users (K Cao 2019 T Zhao 2018) In the instance of untrusted users
dynamic programming and POMDP are subjected to the channel conditions
details optimizing OP and SOP as a restricted parameter accompanied by resource
allocation (Davis 2018 L Hou 2018)
The main aim of the proposed research work areas
bull To analyze the underlying NOMA UAV communication framework with
enhanced Physical Layer security (PLS) implications for particular quest
applications
bull To examine the potential pairing of trusted and untrusted users in the
NOMA-based UAV contact network with two users and multiuser scenarios
for certain channel conditions called Channel State Information (CSI)
bull To maximize resource allocation among trusted and untrusted users by
pairing OP and Secret Outage Probability (SOP) as performance measures
with the POMDP optimization method
bull To evaluate POMDP and dynamic programming resource allocation with
two users and multiple users for both protected NOMA-based UAV
communication network scenarios
19 Thesis Organization
Chapter 1 Provides the introduction and basic concept of the proposed work with
the problem identification motivation and aim and objective of the proposed work
Here we described LTE 4G and its advanced techniques than about the NOMA and
its basic scheme UAV concepts represent their types and basic working strategy
Chapter 2 Provides a survey of the existing technologies which is related to the
proposed work The NOMA transmission schemes Merits and De-merits related
to security UAV assisted communication in heterogeneous sensor networks UAV
networks of 5G and beyond communications has been explained then about UAV-
NOMA PHY secured communication techniques as well
22
Chapter 3 Describes the proposed work of improvement of physical layer
insecurity of the NOMA The overflow and its performance measures with
simulated output have been defined in this chapter
Chapter 4 Describes Migrations proposed work from 4G LTE to advanced PHY
techniques for UAV communication The overflow and its performance measures
with simulated output have been explained in this chapter Concludes and explains
the proposed work with its outcome and the future scope of the proposed work
23
CHAPTER 2
LITERATURE REVIEW
21 Integration of UAV Networks for 5G and B5G communication
5G and B5G had been anticipated to give a unique connection among universal
users The UAV had been emerged for its advantage of wireless network and
relaying high data rate The UAV in the 5G and B5G was introduced and 5G and
B5G were updated with the new concept of Space-Air-Ground Integrated Networks
(SAGIN) Three layers were established named physical network communication
link and evaluation Besides the usage among the dense population IoT was
applied in satellite communication In which the IoT had provided the uninterrupted
service with high data rate communication The scope for flying UAVs had been
created for enhancing the number of mobile users with IoT (Ali et al 2018)
5G and B5G had projected the UAV as the vital constituent One to multiple point
transmission can be possibly advance in 5G and B5G The structural design of the
upcoming UAV (multi-tier drones) was driven by the routine of different structures
like the maximum functioning altitude communication overlap coverage and
determination The UAVs practicability (multi-tier drones) among conventional
UAVs (single-tier drones) is scrutinized in that perspective By ascertaining the
circumstances UAV (multi-tier drones) could supplement the older terrestrial
networks with RF Initially UAV (multi-tier drones) and drone-aided wireless
networks were related to finding the tasks The modified UAV (multi-tier drones)
and the drone-administered wireless networks were analyzed The enactments of
UAV (multi-tier drones) were scrutinized in the contest of spectral efficiency in the
downlink networks Their effect had exhibited the detailed network parameters The
UAV distribution (multi-tier drones) was considered advantageous for the spectral
efficiency from the downlink transmission over traditional terrestrial wireless
networks (Sekander et al 2018)
The growth of 5G and B5G wireless networks prominently hang on the
incorporation of the terrestrial and aerial systems in innovative heterogeneous
network architecture They had advanced a creative and tangible multiple UAV
24
made up of cluster UAV ndash base stations and Poisson point process with UAV and
mm-Wave frequency band Ground user equipment and UAV had exhibited as the
Poisson cluster process and then spread around the public cluster in the distinctive
cluster In particular the scrutiny was accompanied by the accumulation of extra
tiers Extra tiers were made up of multi-cluster UAV base stations and single ground
user base stations in the characteristic cluster Four-tier network systems were
designed correspondingly from the subdivision of the above-said base stations
Two-tier and four-tier association patterns were built for discovering the
involvement of the cluster networks The coverage probability for the downlink and
network throughput was derived (Ji et al 2020) The numerous subordinate title
role of the multifaceted communication systems was performed by the UAVs The
UAV was acted as the air relay in the maintenance of ground networks The UAVs
were used in the countryside hilly zones whereas the communication was
inadequate The author anticipated resolving the viable communication difficulty in
5G and B5G vehicular ad-hoc The associate communication pattern established on
the smart UAVs was planned given the crisis condition of the car ad-hoc The smart
UAVs were supporting the vehicular ad-hoc strong communication in real
situations Above and beyond its actual characteristics of the vehicular ad-hoc were
needed to be endangered to avoid the prohibited features from attaining and
exhausting for law-breaking practices Innovative UAV with a secret authentication
key arrangement was recommended in the 5G and B5G vehicular ad-hoc Because
of supporting efficiency the vehicle network which guaranteed communication
confidentiality was not negotiated The suggested pattern was confirmed to be
unaffected by numerous outbreaks by exploiting the broadly applied natural or
random ROR scheme
Furthermore the projected scheme had well calibrated the communication
overhead from the performance estimation (J Zhang et al 2020) The UANs had
obtained a phenomenal role in the research area the emergent sector of aerial
robotics The parcel transport organization monitoring occurrence shooting
surveillance and tracing were the metropolises general operations utilizing the
UAV Various domains would use 5G and B5G to improve UAV networks UAV
ecological unit was advantageous in present 5G and B5G mobile communications
For UAVs intrinsic features they were concerned for flexible movement of three-
25
dimensional space independent actions and smart locations These devices were
provided with extensive scope in cellular networks The author proposed an in-
depth assessment of implementing cooperation between UAV and 5G and B5G In
which UAV had been assimilated as a novel user equipment of aerial in present
mobile communications The UAV had implemented the duty of flying users within
the network coverage named the cellular-connected UAVs in this amalgamation
The author showed a broad examination of the incorporation tasks with 5G and
B5G novelties Continued efforts in the prototyping and validation of mobile
communication UAVs were conducted using the ground trial The paper had
focused on the current growth in 3GPP The social-economic had not been taken
into account which was considered disadvantageous (Mishra amp Natalizio 2020)
The UAV was anticipated as the significant constituent in the 5G and B5G wireless
networks 5G enables the UAV to be used in broadcasting and end-to-end
communications using the small UAV They needed a devoted and endangered
aerial spectrum in the aircraft cargo by letting small UAVs run in space in
supervisory authority The security information was obtained from the link Control
and Non-Payload Communications (CNPC) The security information contained
the regulation of UAV and the line of sight of terrestrial The CNPC application in
the 5G and satellite communication was scrutinized in this paper Payload
communication like mm-Wave networks and UAV were analyzed in this paper The
direction-finding and reconnaissance difficulties were examined UAV
communication systems were scrutinized and the hardware challenges were
discussed (Hosseini et al 2019)
The potential gain from the UAV-assisted data gathering was found in
indiscriminate IoTs The characteristic propagation was represented by utilizing the
complicated channel method (contained small- and large-scale fading) IoTs were
updated in constrain of transmit power (in high) and total energy The multi-antenna
UAV was selected in the IoTs in sequence The virtual MIMO was created by the
communication between UAV and singe antenna IoT in every transmission (W
Feng et al 2018)
The UAV was applied in the aerial coverage surveillance agricultural prediction
constructional areas and power line supervising and blood donation The flight
26
period increment payload capability fast movement and speedy placements were
implied features in the UAV so that the UAV was exploited by the applications of
5G and B5G (Ullah et al 2020)
The UAV was considered a motivation for many emergent usages and reformed
social-economic welfares The wireless networks for the UAV and the base stations
were desired for the UAV function Mobile communications were considered
suitable for finding tracing and regulating the flying UAV The wireless
communications were selected for their features of broad coverage quality of
service and secrecy The wireless communication in the UAV improved
productivity besides the line of sight (G Yang et al 2018)
22 UAV-NOMA in Physical Layer Security enhancement
The NOMA has been applied in the fifth generation (5G) technology The Multicast
Cognitive Radio (MCR) network is implemented using the NOMA and coined as
MCR- MOMA The transmission side is also included with the superimposition
code The decoding was applied at the receiving end So an unknown user is
deduced in their methodology (Meng et al 2020)
The physical layer security for the cooperative NOMA was examined Amplify
and forward decode and forward were taken into consideration for achieving
secure transmission (Chen et al 2018)
The physical layer security of the NOMA was analyzed in the broader network with
varying locality The single and multi-antenna were established in the following
cases The single antenna was taken for an end-to-end connection in a secured
manner And the multi-antenna was used for the connection of base station and
random user Finally achieved security for the multi-antenna on the transmission
side The security of the single antenna was attained by introducing the excluding
area for eliminating eavesdroppers The individual expression of security outage
probability for both single antenna and multi-antenna were derived (Yuanwei Liu
et al 2017)
The secure transmission of NOMA in large-scale applications was investigated
Stochastic Geometry was utilized for placing the eavesdropper and user nodes The
equation for secrecy outage probability was derived and expressed for evaluating
27
secure transmission Security can be improved by expanding the protected zone
(Qin et al 2016)
The power domain NOMA had the disadvantage of decoding data by other
unauthentic users of the same source For reducing unauthentic users the base
station should treat the unauthentic users with different cleaning methods The
secrecy outage probability was investigated for authentic users and unauthentic
users Both users were combined as a pair to the non-uniform distribution of original
and unauthentic users The pair outage probability of genuine users from the secrecy
outage probability restrained NOMA authentic users The derivation for pair outage
probability and the secrecy probability were expressed for calibration The
combined system had been the better security (ElHalawany amp Wu 2018)
The physical layer security was considered problematic in the wireless networks
mainly for keeping the authentic userrsquos data The UAV was acted as the base
station UAV based base station had sent the extensive data to the original users
NOMA with the multi-antenna with mm-Wave frequency band transmission had
enhanced the spectral efficiency The physical layer security was attained by
announcing the space around user locality as the eavesdroppers protected zone
Covering the entire eavesdropper area was considered a resource-consuming way
The shape optimization for the protected location in each UAV base stations
altitudes was introduced The derivations for the secrecy sum rate and the secrecy
outage probability were expressed (Rupasinghe et al 2018)
The vehicular communication system had used cooperative NOMA The secrecy
outage probability was considered in vehicular communication The relay can be
used in both modes (half-duplex and full-duplex) in vehicular communication The
closed derivation for the secrecy outage probability was expressed The security of
the full-duplex NOMA resulted better than that of the half-duplex NOMA The
limitations are that the velocity of the vehicles was not considered Figure 21 is
illustrated the conceptual model of the vehicular communication NOMA system
(Xie et al 2019)
28
Figure 21 Vehicular communication NOMA system
The physical layer security of the uplink NOMA of the large-scale devices was
examined The connection networks had investigated with the approach called
stochastic geometry The new derivation was expressed for the coverage
probability The protected zone restrains eavesdroppers to the authentic users
Efficiency secrecy throughput was examined wiretap channels and the many
original users Constant transmission and variable transmission were collectively
inspected The signal to noise and the movement to interference ratio were derived
drastically (Gomez et al 2017)
The wireless system was executed using Space-Time Block Coding (STBC)
approach in the NOMA of mm-Wave MIMO The technique focused on haphazard
users So the pairing method was introduced mainly for Random Near-Random Far
(RNRF) Here the latent period could be minimized and the RNRF has also been
deduced for the overhead issue The result revealed the systems efficiency with a
proper implementation (Ghavidel et al 2020)
The recent arbitrary beam forming method was proposed in the multiple access
NOMA The pairing had decided to the user places So the evaluation was focused
on the system overhead The result revealed that the proposed work outperformed
29
the existing methods (Aghdam et al 2020) NOMA enhances the reliability of
multi-users transmission The sum rate could be reduced for improving Quality of
Service (QoS) power transmission and signal outage probability The
eavesdropper easily accessed the multi-access systems that cause physical security
during transmission (Z Li et al 2020)
The NOMA had provided spectral efficiency speed transmission of data multiple
networking and less latent period The NOMA utilizes the power domains for
various access Cognitive Radio Networks (CRN) is used to screen illegitimate
users The legitimate users were only permitted in the CRN by the Primary User
Networks (PUN) QoS The cooperative NOMA here implemented with the PUN
and the system performance is enhanced The spectral efficiency can be improved
by the secured transmission The cooperative NOMA was additionally developed
in the CRN with the PLS A new method of cooperative NOMA in the CRN was
examined The PUN technique attains a secure transmission Multiple antennae
were used in this study for reliability and the eavesdropperndashexclusion zone method
is used for better security (B Li et al 2018)
The downlink NOMA for moderate CSI was examined The challenge of the power
domain was rectified by allocating power NOMA The power in NOMA and that
of the OMA was analyzed which resulted in a significantly reduced NOMA (Cui
et al 2016)
Here the users were multiplexed by the power domain So the method was coined
as power domain NOMA The demand arising from the B5G (Beyond 5
Generation) had reached using power domain NOMA Machine learning in the
NOMA was described (Maraqa et al 2020)
The uplink NOMA with the PLS was proposed The uplink NOMA contained a
single base station and multi-users a couple of users combined for NOMA The
known jammer emitted the pseudo-noise to divert the eavesdroppers The study had
suggested the two jammers in the uplink NOMA for secure transmission (N Zhao
et al 2020)
The Intelligent Reflecting Surface (IRS) is designed using downlink NOMA The
multi-access had used the space direction of the beams of closure users The IRS
30
had performed the multi-access for every spatial order by the cell edge users of the
orthogonal beams (Ding amp Poor 2020)
The multi-input single-output NOMA has introduced the technique called Secrecy
Beam Forming (SBF) SBF had utilized the artificial noise for NOMA security
aided users in which the eavesdropperrsquos channels deteriorated The SBFs secure
transmission can be achieved in which high successive interference cancellation is
gained (L Lv et al 2018)
The superposition coding was performed in the transmission pat The successive
interference cancellation was conducted in the receiving position These two
techniques were combined in the novel 5G aided NOMA The basic concepts of
uplink and downlink NOMA were mentioned The dominant condition was
performed in the two user clusters of NOMA The prevailing state had issued the
confirmed spectral efficiency gain in NOMA (Tabassum et al 2016)
The relay scheme in IoT was examined for the secrecy of NOMA This was coined
as relay selection NOMA The base station had transmitted the secret messages to
the two NOMA-aided sensors and eavesdroppers IoT had treated the sensors and
eavesdroppers with different power allocations The expression for certain outage
probability and the strictly positive secure capacity was derived Increasing the
number of the relay would enhance the security in the NOMA-aided IoT The
outage probability for NOMA and OMA were compared The NOMA resulted in
better outage probability in Decode and forward mode (Do et al 2019)
31
Figure 22 RS-NOMA against an external eavesdropper
The NOMA-aided IoT was utilized to fight against the external eavesdropper as
Figure 22 The secured NOMA was proposed The base station sent secret
messages to several authentic destinationsmdashseveral eavesdroppers and unauthentic
users
Nakagami-m fading model was carried out using the multiple antennae in the
channel The security was attained using the max-min transmit antenna selection
scheme Both authentic and unauthentic eavesdroppers were analyzed The closed
derivation for the cumulative distribution of the original user was expressed first
That was compared with the unauthentic user The derivation for the secrecy outage
probability was obtained to identify the level of secrecy performance (Lei et al
2018)
Reconfigurable intelligent surface (RIS) aided NOMA was established for the
secrecy performance The main disadvantage of this model was the chance of using
RIS by the eavesdropper The secret outage probability was derived in this paper
The RIS improved the secrecy of the traditional NOMA The eavesdroppers were
limited from receiving the RIS signal by enhancing the number of intelligent
elements in the RIS A high signal-to-noise ratio was obtained from this experiment
(Liang Yang amp Yuan 2020)
32
The cooperative relaying NOMA was proposed for improving private transmission
in wireless networks Full duplex mode transmitted the jamming signals That
received the required communication at first Secondly the jamming signal
emission was sent by the base station The power allocation for the jamming signal
and information signal was decided on the eavesdropper channel state information
The eavesdropper was jammed by the signal from the first phase with maximum
power Second the derivation of the secrecy outage probability was expressed by
static eavesdropper CSI (Y Cao et al 2020)
The NOMA achieved spectral efficiency and secrecy The security of the multi-
NOMA users was obtained by the successive interference cancellation (SIC)
decoding in the receiving node The conservation of the untrusted NOMA was
concentrated in this study The security can be confirmed by the properly secured
decode processing and allocating power The decoding scheme was implemented
for aiding NOMA users The decoding was performed for enhancing the sum-rate
(Thapar et al 2020) The cognitive radio network in NOMA with the external
eavesdropper was proposed (Mehr et al 2020)
The cooperative NOMA was used in the field of energy harvesting communication
The novel relaying technique was introduced for achieving secrecy The secrecy
outage probability was derived and the derivation was expressed for the three
conditions The first condition was the derivation of CSI with a passive
eavesdropper The second condition was the derivation of CSI with the unauthentic
eavesdropper The third condition was the derivation obtained from the multi-relay
nodes The increased SNR resulted in high security The increase in the number of
users deduced security This was considered a disadvantage (Salem et al 2020)
Satellite communication covered more range of broadcasting So the security
challenge was considered a big difficulty in satellite communication Downlink
NOMA was assessed with an eavesdropper for the examination of secrecy The
paper concentrated on the physical layer security of downlink satellites Here two
methods were proposed The frequency-domain NOMA was considered for gaining
spectral efficiency The multiple user interferences were obtained in the process of
overlapping Introducing a suitable technique can be performed the security for the
number of users The secrecy rate was analyzed for all authentic users (and the
33
eavesdropper) and expressed in the derivation The safety was improved using the
spectral overlap method (Yin et al 2019)
The NOMA was considered as the emerging scheme in the upcoming wireless
networks The secrecy sum rate for the downlink NOMA (with MIMO multiple
inputs multiple outputs) was examined Downlink NOMA had the base station
number of users and the eavesdropper In the limitation of transmit power and
optimal successive interference cancellation the security was expected to enhance
Downlink MIMO NOMA was considered advantageous because of its secrecy
performance and the practical usage of bandwidth The mutual information rate and
the mean square error were causing the secrecy rate optimization to the problem of
biconvex This was rectified through the alternative optimization method and the
second-order cone programming was solved (Tian et al 2017)
Table 21 Comparative analysis
The comparative analysis for the physical layer security was examined in existing
studies
SR
No
Details of Author wise Contribution to NOMA Technology
1 Author (YFeng Yang amp Yan 2017) Secrecy performance in NOMA was
conducted with the help of artificial noise in the full-duplex mode of relaying
Methodology The optimization of the power was calibrated for the source
information and the noise signal The closed derivation for the secrecy outage
probability was expressed
Usage and limitations The physical security was increased
34
2 Author (He Liu Yang amp Lau 2017) NOMA was developed in the constrain
of security
Methodology The secret message had been sent to some users and also to the
eavesdropper The Novel decoding process was conducted for excluding the
unauthentic users The iterative algorithm was used for power optimization
Usage and limitations Transmit power was reduced The quality of service
was availed
3 Author (D Wang et al 2020) The secrecy was performed in the NOMA
The security was developed against the eavesdropper outside
Methodology The channel state information was analyzed for secrecy The
quantization of CSI had performed for secrecy The derivation for the secrecy
and transmission outage probabilities were obtained
Usage and limitations The secrecy rate was enhanced
4 Author (L Lv et al 2020) The physical security of the NOMA was
improved by adding artificial noise jammer and inter-user interference The
mode of full-duplex in the updated version was used in the NOMA
Methodology The eavesdropper can be trapped the superimposed signal from
the source So the secrecy was affected
Usage and limitations The spectrum usage is effective in the NOMA
transmission scheme Numerous connections can be performed in the NOMA
NOMA is considered to be the most advantageous for the upcoming
generation communications The superimposition technique was followed
4 Author (Yue et al 2020) Secrecy performance of the NOMA was developed
with a unique framework
Methodology The eavesdroppers inside the zone and outside the coverage
zone were examined properly in this paper The outage probability for codendash
power domain NOMA was derived
Usage and limitations Safety was acquired for both internal eavesdropper
and external eavesdropper in this scheme
35
5 Author (Guezouli et al 2020) The heterogeneous sensor network of cellular
communication was taken into account
Methodology Unmanned aerial vehicles are utilized the heterogeneous
sensor network of cellular communication
Usage and limitations Extended the life span of the network system The
cost of the hardware components is drastically low The random and the
repeats in the speedy movement The latency is maximized The coverage
period is maximum
6 Author (Yao amp Xu 2019) The security in transmitting a large amount of
information in the wireless network systems are analyzed with unmanned
aerial vehicle UAV
Methodology The numbers of UAVs are arranged in the space The base
station sent the information to the UAV in the space The authentic receivers
have obtained the secured information from the UAV The HPPP
homogeneous Poisson point process is used for distributing the authentic
receiver and eavesdropper in the line of sight
Usage and limitations The increase in the number of safety zone causing the
secured transmission
7 Author (Saacutenchez et al 2020) Physical security can be achieved by the
method of a unique encryption scheme
Methodology The physical layer security of the following schemes is
discussed in this paper mm-wave NOMA massive multi-input multi-output
heterogeneous sensor networks full-duplex mode
Usage and limitations The physical layer security was analyzed for the 5G
supporting technologies Good reliability achieved The less latent obtained
Machine-type communications can be enabled
36
8 Author (Hou et al 2018) The multi-antennas were used in NOMA with
UAV The stochastic geometric approach was examined
Methodology The multi-input multi-output kind of NOMA was utilized In
common the stochastic geometric approach was used for drastically moving
NOMA
Usage and limitations The maximum signal-to-noise ratio was obtained in
this scheme Power optimization was achieved The path loss is less Good
spectral efficiency was obtained
9 Author (Miao et al 2020) The broadcast type of communication was
performed The less weighed three-dimensional space for 5G communication
was analyzed
Methodology Both the performances of multicast and broadcast were
enabled UAV-assisted 5G communication systems are emerging in the
upcoming wireless networks
Usage and limitations Better flexibility in the network Continuous mobility
One lined line of sight
10 Author (Majhi amp Mitra 2020) The secure communication in cognitive radio
by NOMA was propounded
Methodology The antenna strategy of giving minimum outage probability
was concluded from this study
Usage and limitations The limitation is that more spectral efficiency causes
security issues
11 Author (X Zhao amp Sun 2020) Secure communication of the physical layer
in Visible light NOMA Communication was proposed
Methodology Energy optimization in security constrain was propounded for
achieving overall performance
Usage and limitations It is difficult to find optimal results because energy
optimization is the nonconvex issue
37
12 Author (Tuan amp Hong 2020) Secure communication in simultaneous
wireless information and power transfer NOMA was remitted
Methodology Eavesdropper is used for security purposes between the user
and base station using energy relays Known jammer is used for secure
transmission For energy efficiency storing and transferring were propounded
Usage and limitations Jamming requires extra power allocation
13 Author (Vaezi et al 2019) NOMA for 5G in mmWave MIMO cooperative
and cognitive were analyzed in this study
Methodology SWIFT NOMA is useful for weak receivers
MIMO using more antenna
Usage and limitations multi-antenna utilization cause high power
consumption
14 Author (Vaezi et al 2019) Mobile edge computing NOMA was proposed to
optimize power
Methodology Minimum latency and less power consumption
Usage and limitations Transfer power allocation must be calibrated
15 Author (Faraji-Biregani amp Fotohi 2020) Security in UAV communication
was proposed by introducing mobile agents
Methodology Malicious user of UAV was identified
Usage and limitations Three-phase power is essential
16 Author (G Zhang et al 2019) Secure communication in 5G UAV was
propounded by joint trajectory carrying out in physical layer
Methodology Power optimization was proposed for security
Usage and limitations Security in the physical layer was achieved by
optimization of trajectory
17 Author (Fotohi et al 2020) Agent-based self-protection was propounded in
UAN for secure communication
Methodology This method imitates the immune system of human beings
Less cost
Usage and limitations Energy is not optimized properly This approach
needs to consider other malicious attackers
38
18 Author (Shang Liu Ma amp Fan 2019) Vehicle to everything approach was
propounded for security in a UAV
Methodology Security of vehicle to the vehicle was proposed by considering
eavesdroppers active and passive attacks
Usage and limitations High price
19 Author (Kantor et al 2017) The flight path was calibrated in a UAV
Methodology Security performance was achieved by encryption as well as
anonymization
Usage and limitations High in cost and hardware structure occupies more
place
23 Research Methodology
The NOMA-based cellular architecture for UAV communication has been
considered here as reference network architecture Rayleigh fading has been
assumed as a channel characteristic The performance parameters for PHY layer
security are (1) Pair Outage probability (Pair OP) between two users trusted near
user designated as U1 and untrusted far user designated as U2) and (02) Secrecy
Outage Probability (SOP) of trusted near user designated as U1 The aim is to
achieve optimal Pair OP for the given constrained SOP of User U1 so that network
resources can be efficiently allocated to both users without compromising the
secrecy of trusted User U1
The mathematical analysis from reference literature (ElHalawany et al 2018) has
verified and supported the joint optimization of the Pair OP and SOP for the given
power allocation factor in NOMA This research work is extended as providing
more efficient resource allocation using the POMDP algorithm in a given scenario
First the varying distance of untrusted user U2 from BS as a critical selection
parameter that affects Pair OP amp SOP of user U1 and U2 both has been simulated
and the feasible and infeasible pairing of both users have been analyzed The
optimal power allocation factor for feasible pairing as the constrained problem is
optimized by opting for POMDP as a resource allocation algorithm wherein the
SOP of user U1 is strictly maintained for given CSI POMDP provides optimum
39
power allocation factor for trusted and untrusted users pairing as shown in the
proposed flow of POMDP algorithm is used to model a variety of real-world
sequential decision-making problems After the BS has been set up the distance
between the BS and the user is calculated and if space is less than 200m it is
defined as a trusted user While if the range is more than 200m it is described as
untrusted users In the case of trusted users the channel state information (CSI) is
provided to the proposed algorithm POMDP for reliable and efficient resource
allocation
24 Summary
UAVs play a central role in providing network service recovery in a disaster-
stricken region enhancing public safety networks or handling other emergencies
when Ultra-Reliable Low-Latency Communication is required In particular UAV-
assisted communication can be regarded as an important complement to the 5G
cellular networks Surveyed literature related to UAV communications published
over the past several years emphasized the cybersecurity and channel modeling for
UAV communications etc Security is one of the critical issues in communications
Modern communication networks are based on the layered architecture from the
physical layer up to the application layer A great deal of effort has been made to
develop the cryptographic protocols above the physical layer However the
physical layer is not as robust as that in wired communications The physical layer
in wireless communication is more complex than the counterpart in other
communication paradigms The concerns come from not only the noises but also
many types of fading Recently there has been an influential interest in studying
the security issues in the physical layer Security is highlighted as another
challenge and the implementation of physical layer security techniques is seen as
a difficult task PHY security in NOMA systems under the presence of external
eavesdroppers or untrusted relay nodes Upcoming 5G networks for unpredicted or
crisis (disaster management) the placement of terrestrial substructures is
economically infeasible and challenging due to high operational expenditure as well
as sophisticated and volatile environments
To address such novel issues intelligent heterogeneous architecture by leverage
UAV has been well-thought-out to be a promising novel model For advancing the
40
performance of the UAV 5G communication system physical layer techniques are
of many effects as they have impacted the applications of UAVs Security of
NOMA-based UAV communication network has been scrutinized for optimization
as physical layer security
41
CHAPTER-3
SYSTEM MODEL FOR NOMA-UAV
COMMUNICATION
31 NOMA-UAV System Secured Communication for 5G
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
311 The basic scheme of NOMA
The NOMA system allowed several users to be served simultaneously by the
transmitter To transfer a linear combination of different signals towards the
recipient the system of proportional representation superposition coding (SC) The
transformed signal is provided through
σ ඥ119875119896 119878119896119870119896 =1 -------------------------------------- (1)
Where 119927119948 represents the transmit power assigned toward user k th
119930119948 indicates the normalized message used for user k th
42
The instantaneous total converses power is σ 119927119948119922119948=1 The received signal at user kth
and the eavesdropper are offered through
119910119896 = ℎ119896 σ ඥ119875119896 119878119896119870119896=1 + 119899119896 -------------------------- (2)
119910119890 = ℎ119890 σ ඥ119875119896 119878119896119870119896=1 + 119899119890 -------------------------- (3)
Where 119951119948 and 119951119942 indicated the zero-mean Additive White Gaussian Noise
(AWGN) at user k th with variance 1205901198962 and the zero mean AWGN at eavesdropper
with variance 1206481199422 respectively We assume that the noise variances at all the users
are identical
ie 12059012 = ⋯ = 120590119896
2 = 1205901198902
As per NOMAs process the SIC is followed by all users to decrypt the message to
the same decoding order Notice that it is not known what the optimal decoding
order is for the NOMA method that corresponds to secrecy
Therefore the mth message to be encoded to the user might not be the mth message
to the user As such we also have to add the π variable For example if 120587(1) =
3 then the first message to be decoded for the SIC is the message for the user 120645(119947)
forall j lt k before decoding its letter to remove the inter-user interference successively
Then the user 120645(119948) denotes its message while treating the news for all the user
120645(119946)foralli gt k as the interferences The received Signal-to-interference-plus ndashnoise
ratio (SINRs) at user 120587(119896) k lt K and user 120587(119870) to decode their messages are
respectively given by
119878119868119873119877120587119896=
120574120587(119896)119875120587(119896)
1+120574120587(119896) σ 119875120587(119894)119896119894=119896+1
119896 lt 119870 --------------------(4)
119878119868119873119877120587119870= 120574120587(119870)119875120587(119870) --------------------------------------(5)
Were 120574120587(119896) =หℎ120587(119896)ห
2
1205901199062
൘
43
Also the acknowledged SINR at user 120587(119898) to decrypt the message 120633120645(119948) 119896 lt
119898 le 119870 is given by
119878119868119873119877120587119896=
120574120587(119898)119875120587(119896)
1+120574120587(119898) σ 119875120587(119894)119896119894=119896+1
kltmle 119870 --------------(6)
Similarly the acknowledged SINRs by the eavesdropper of the message 120575119896 119896 lt
119870 and the message 120575119896 are respectively given by
119878119868119873119877120587macr
119896=
120574119890119875120587(119896)
1+120574119890 σ 119875120587(119894)119896119894=119896+1
klt119870 ----------------- ------(7)
119878119868119873119877120587macr
119896=
ȁℎ119890ȁ2119875120587(119896)
1205901198902 = 120574119890119875120587(119896) klt119870 ---------------------(8)
Where 120574119890=ȁℎ119890ȁ2
1205901198902൘
Notice that here expressions for the obtained SINRs at eavesdropper overestimate
the skill of eavesdropper Here a worst-case inference from the viewpoint of
legitimate users is made That is the messages have already been decrypted by the
eavesdropper for all users π (j) forall j lt k before attempting to decrypt the message
for the user π (k)
The presumption also assumes that the decrypting order and power distribution are
understood by the eavesdropper The eavesdropper may or may not recognize the
decoding order of the users and the allocation of power may or may not recognize
the messages for all users π (j) forall j lt k before attempting to decode messages for
users π (k) However since the eavesdropper has been unable to alert the authorized
customers of its capacity and the current CSI the approved user would be unable
to know the eavesdroppers details Therefore we have to pursue the worst-case
scenario for the permissible users point of view due to the liberality required by the
safety reports It highlights that the worst-case assumption in the study and design
of transmission schemes with secrecy requirements has been generally adopted
The proposed study has been evaluated using performance measures Here we
analyze NOMA with downlink and uplink networks suggested by SINR and Sum
44
Rate survey High SNR is then simulated to contrast the OMA and NOMA
processes
312 Downlink of NOMA
The Downlink of the NOMA network on the transmitter side is described in Figure
31 SIC method is supposed to be carried out successively on the receiver side of
each user until another signal is restored The coefficients of users are owed in an
inversely proportional manner based on their available bandwidth
Figure 31 Downlink NOMA network
A consumer with a poor available bandwidth has a transmission capacity of a
higher range than a consumer with strong available bandwidth As a consequence
the consumer with the higher power assumes the signals of other users to be noisy
and automatically restores the signal without conducting any SIC operation The
receiver of each consumer detects indications that are stronger than those of the
desired signal These impulses are then deducted from the power and this process
continues until the signal has been calculated Both users decrypt their signaling by
considering other users with lower correlations The signal is calculated as
45
119904 = σ 119886119894119875119904119883119894119871119894=1 -----------------------------------------------(1)
Where Xi is the user ithrsquos information through unit energy
Ps is the capacity of transmission at the BS
ti is the coefficient of power assigned for user i
Although without the need for lack of generality the channel profits are expected
to be graded as ȁℎ1ȁ2 le ȁℎ2ȁ2 le ⋯ ȁℎ119871ȁ2
Where 119945119923 is the coefficient of the channel of the user Lth
The received signal of the Lth user is calculated as
1199101 = ℎ119897119904 + 119899119897 = ℎ119897 σ ξ119886119894119875119904119883119894119871119894=1 + 119899119897 -----------------------------(2)
Where n1 is zero mean Complex Gaussian noise with a variance of 1206482SINR
analysis with the equation (2) the SNR of Lth user to identify the user 119895 le 1with
119895 ne 1
119878119868119873119877119871 = 1198861120574 ȁℎ1ȁ2120574ȁℎ1ȁ2൘ σ 119886119894 + 1119871
119894=119871+1 ------------------------(3)
Where 120632 = 1198751199041205902ൗ represents the SNR
Sum rate analysis After identifying the SINR of the downlink the sum rate will
also be done quickly
The NOMAs downlink data rate of Lth user can be calculated as
1198771119873119874119872119860minus119889 = 1198971199001198922(1 + 119878119868119873119877119871) --------------------(4)
313 Uplink of NOMA
The Uplink NOMA is depicted in Figure 32 where each user sends a signal to the
BS SIC iterations are supported to classify the signals of mobile users If both
channels are identical and BS sends the coefficients of power allocation to mobile
users the received signal can be interpreted as a synchronous uplink to the NOMA
46
119955 = σ ℎ119894ඥ119886119894119875119909119894119871119894=1 +n ----------------------------------(5)
Where hi is the coefficient of the channel for the ith user
119927119961119946 is the extreme transmission capacity supposed to be general to all users
N is zero-mean Gaussian noise with a variance of 1206482
Figure 32 Uplink NOMA
Analysis of SINR The BS decrypts the signals of the users as per the coefficients
of the users and the SINR for the Lth user can be defined as
119878119868119873119877119871 = 119886119897120574ȁℎ119897ȁ2120574 σ 119886119894ȁℎ119894ȁ2 + 1119897minus1
119894=1൘ ----------------------------(6)
Where 120574 = 1198751205902ൗ indicates SNR
Analysis of Sum rate The sum rate of uplink NOMA when 120632 minus infin can be
computed as
119877119904119906119898119873119874119872119860minus119906 asymp 1198971199001198922(120574 σ ȁℎ119897ȁ119871
119894=1 2 ------------------------ (7)
47
314 Comparison of NOMA and OMA
The attainable data rate of the Lth user of OMA intended for both uplink as well as
the downlink is estimated as
119877119904119906119898119874119872119860 = σ 120572 1198971199001198922120574(1 +
120573119897ȁℎ119897ȁ2
120572119897119871119894=1 ) --------------------------(8)
Just for convenience two users should evaluate the summation of uplink rates for
NOMA and OMA The use of both the uplink rate of NOMA and OMA at high
SNR can be calculated as---
119877119904119906119898119873119874119872119860 asymp 1198971199001198922(120574 ȁℎ1ȁ2 + 120574ȁℎ2ȁ2 ------------------------- (9)
equation (7) and (8) it is seen that 119877119904119906119898119874119872119860 le 119877119904119906119898
119873119874119872119860
Here we note 119929119956119958119950119926119924119912 le 119929119956119958119950
119925119926119924119912 shows that NOMA performed better than OMA in
terms of sum rate in both downlinks as well as uplink of two user networks
The sum rate will be calculated after the SNR as the formulation is shown In this
proposed work multiple users are propagated to the process of NOMA and here a
comparison of NOMA as well OMA has been defined The NOMA uplink and
downlink using the OFDMA method for the
32 PLS performance metrics in NOMA -UAV communication
This chapter mainly describes the proposed work to examine the availability of the
outage probability of the pair below an authorized user According to the decryption
of SIC availability and spectrum sharing the unauthorized user can function as an
eavesdropper and obtain an outage probability (OP) for all situations with the
Secrecy Outage Probability (SOP)
321 SOP and OP - two user and multi-user NOMA system
NOMA system has the capability for assigning multiple data over the transmission
signal through high-level coding (Shim amp An 2018) Thus it contains spectrum
efficiency when opposed to OMA But this has a limitation in security As an
48
instance if the eavesdropper is reached then it obtains multiple user data in the
interference of the NOMA signal Thus the security issues are more significant in
this system Here PLS is an available method to rectify the attack intended for
malicious users (Dai et al 2015)
Additionally data should be transmitted confidentially if the root and eavesdropper
networks can be evaluated and the recipient can decrypt the received text At the
same time the eavesdropper is not able to solve the text that has been interrupted
PLS is at the cutting edge of wireless communication security technology to prevent
eavesdropping attacks The SOP is described as the likelihood that the near users
attainable device confidentiality capability will fall under the predefined target
confidentiality rate as set out in (Shim et al 2017)
Through SOP we can calculate the level of protection of the device As an example
the low-secret OP system makes the system more stable in terms of security than
the high SOP system To boost the efficiency of the PLS CSI-based opportunistic
scheduling links to a scheduled destination in a particular time slot It has been
documented as an enticing scheduling scheme (Long Yang et al 2016) because the
various wireless channel has been exploited Opportunistic scheduling is also
considered to be one of the strategies used to increase the confidentiality efficiency
of the NOMA method
322 System Model
Suppose a multi-user NOMA system of downlink containing BS a selection of K
nearer users as N= 119873119894ȁ12 119870 and a range of M far users as F=
119865119895ȁ12 119872 and an eavesdropper E as displayed in Figure 33 More
specifically nearer users should make active use of the SIC methodology to
distinguish far user F Both the legitimate and illegitimate receivers are furnished
through a single antenna and operate in a half-duplex manner
49
Figure 33 Multi-two user architecture of NOMA system (Shim amp An 2018)
Here 119945119935119936 and ȁ119945119935119936ȁ2
Where X120598ሼ119878ሽ 119884120598119873 cup ሼ119864ሽ represent the channel coefficient and the corresponding
channel gain of the X-Y value
Taking into consideration that each wireless channel for Rayleigh block fading 119945119935119936
can be incorporated as an independently distributed random Gaussian variable with
zero mean and affirmative ℷ119935119936 Variance The outcome of channel gain ȁ119945119935119936ȁ2is an
exponential variable randomly through the Probability Density Function (PDF)
119891ȁℎ119883119884ȁ2(119911) = ቀ1
ℷ119883119884ൗ ቁ 119890119909119901 (minus 119911
ℷ119883119884ൗ )
if zge 0 119900119905ℎ119890119903119908119894119904119890119891ȁℎ119883119884ȁ2(119911) = 0 -----------------(1)
Especially the average channel profit can be represented as
ℷ119883119884= ൬119889119883119884
1198890൘ ൰
minus휀
ℒ ------------------(2)
When 120027 is the attenuation of the received signal 119941119935119936 signifies the distance among
X and Y 1199410 indicates the space and 120656 is the exponent of the path loss It is believed
that the source is entirely familiar with the CSI of both legitimate users and
eavesdroppers
50
323 Partially Observable Markov Decision Process-POMDP
Figure 34 Flow Diagram of the proposed system
The proposed overflow is shown in Figure 34 After the BS has been set up the
distance between the BS and the user is calculated and if space is less than 200m
it is defined as a trusted user While if the range is more than 200m it is described
as untrusted users In the event of untrusted users the channel state information is
accessible to the POMDP accompanied by the allocation of resources The study
was carried out after the machine operation Here a NOMA-oriented cellular setup
provided with a BS at the Centre and two users was described in Figure 35
51
Figure 35 Near and Far User
The adjacent user has a high level of security confirmation needed to protect the
layer since the low-security clearance user is situated at a distance away from the
BS P is specified as the highest level of transmitting power In this chapter it is
presumed that all DNS servers are furnished utilizing an individual antenna and all
channels are supposed to be individually static identical to the Rayleigh
dissemination concerning distribution
119862119873(0 120575119898
minus120572
212059601 2Τ
)
In which 120633119950 is the range between the BS and the nodes 119932119950 Here the path-loss
exponent and constant are defined as 120630 and 1206540 Furthermore BS is assumed to
have predicted the position of the user so that a better CSI can be obtained at BS
that is elaborate in user pairing
The BS transmits the superimposed mixture
119909119905 = ඥ1199051199041 + ඥ1 minus 1199051199042 ------------------------------- (3)
In which 1199561 and 1199562 are the unit of power signals received by users 1199321 and 1199322
respectively t is the power allocation coefficient for the adjacent user
1199031 = ℎ1119909119905ξ119875 + 1198991 ------------------------------- (4)
1199032 = ℎ2119909119905ξ119875 + 1198992 ----------------------------------(5)
Where 1199451119886119899119889 1199452 the channel profit link with the fading of small scale since the
BS to the user 1199321 and 1199322 respectively The additional Gaussian noise with variance
52
is denoted 1199511 119886119899119889 1199512 and zero mean 119894119904 119889119890119899119900119905119890119889119886119904 (1199250) and it is assumed
that the BS conveyed SNR is 120646 = 1199271199250
ൗ
In the NOMA technique additional users with more power may decode their signal
by recognizing the adjacent signal as noise without decoding the adjacent user
message In the previous equation 1198801 is supposed to first solve a weak signal by
decoding its own SIC signal1198802 which is an unauthenticated user attempted to
decrypt the nearer user text after decrypting the adjacent usage text after decoding
its own SIC message The following equation has therefore been achieved
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2 ----------------(6)
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2 ----------------(7)
119879119900119905119886119897119904119894119899119903 = 11987811986811987311987721 1198781198681198731198771
1 119878119868119873119877221198781198681198731198771
2 -----------------(8)
Where 119930119920119925119929119950119951
indicates the SINR ratio of user mth that was decoded by 119932119951 for
119898 119899 isin ሼ119894 2ሽ and the channels gain followed an exponential distribution with the
parameter 120649119950=120654120782120633119950minus120630
324 Problem formulation
As a result the BS could achieve and provide better communication for users who
are vulnerable to security threats from unauthenticated users the proposed
framework identified two kinds of QoS energy efficiency that could be considered
essential for addressing the problem In a particular study a pair of OPs was
specified to check the reliability at which the attainable data rate for users is equal
to or greater than the threshold of minimum reach The following issue aimed at
reducing the pair OP to an SOP factor intended for the user 119932120783 that is provided by
Where 1199270is Outage Probability- (OP)
1199271 is Secrecy Outage probability user U1 119930119926119927(119932120783) and
120631 the permissible SOP threshold
53
33 Performance Analysis Improving PLS Insecurity of NOMA
System
331 The Pair OP Calculation
Through Shannons capacity formula and assuming 119914120783119957119945 119886119899119889 119914120784
119957119945 as the
threshold capacities of users 119932120783 119886119899119889 119932120784 respectively the combination of OP
could be offered by
119927119954 = 120783 minus 119928120783119961119928120784 in which 120649119950 = 120784119940119950119957119945
119950 isin ሼ119946 120784ሽ -------------(9)
empty120783 =120649120784
120646(120783+119957+120649120784119957) empty120784 =120649120783
120646119957
119928120783 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ 120782 lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 ------------------------(10)
Case 1empty1 gt empty2 for having the limitation of the allocation of power factor (t)
required to be satisfied (tgt120649120783
120649120783+120649120784+120649120783120649120784) and for this case 119928120784 could be attained as
follows
119928120784 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ
120649120783
120649120783+120649120784+120649120783120649120784lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 --------------(11)
Case 2 empty1 lt empty2 Like case 1 it was stated that the opposite constraint depends
on
t gt 1206491
1206491+1206492+12064911206492 and 1199282 can be evaluated as follows
119928120784 = ൝119942119961119953 ቀ
minusempty120784
120649120783ቁ 120782 lt
120649120783
120649120783+120649120784+120649120783120649120784
120782 119952119957119945119942119955119960119946119956119942 ---------------------(12)
54
Table 31 List of parameters
Parameters Description
N Number of nearer users
M Number of far users
E Eavesdropper
ℎ119909119910 Channel coefficient between 119909119905ℎchannel and 119910119905ℎ users
119889119883119884 The distance among x and y
1198890 Space
120598 An exponent of the path loss
ℒ Attenuation of the received signal
120575119898 the range between the BS and the nodes
1205960 Path loss constant
120572 Path loss exponent
1199041 1199042 Unit of power signals received by users 1198801 and 1198802
T Power allocation factor for the adjacent user
ℎ1119886119899119889ℎ2 Channel coefficient of 1198801 and 1198802with the fading of small
scale
11989911198861198991198891198992 Gaussian noise variance
1198730 Zero mean for Gaussian noise
120588 Signal to noise ratio
119878119868119873119877119898119899
Signal to interference noise ratio of users n and m channels
55
120591119898 Exponential distribution parameters
1198750 Pair of OP
1198781198741198751 119878119874119875(1198801)
120573 The permissible SOP threshold
Table 31 depicts the list of parameters used in the proposed methodology which
are useful for assigning and the values are assigned based on the parameters given
for the experimental evaluation as well This chapter concludes with the basic and
the actual flow of the proposed method to know more about the work in the
simulation process
332 Pseudo-code for the proposed algorithm
Algorithm I
Step 1 Estimate Rayleigh distribution
119862119873(0 120575119898minus120572 2Τ
1205961199001 2Τ
) where
120633119950 is the distance between nodes 119932119950 and the BS
120630 is the path-loss exponent and
120654119952 is the path-loss constant
Step 2 The BS broadcasts the superimposed mixture and input signal as follows
119909119905 = ξ1199051199041 + ξ1 minus 1199051199042
Where 119956120783 and 119956120784 are the unit power signals received by users 119932120783 and 119932120784
respectively 119957 is the Power allocation coefficient for the near user
Step 3 The received signal is as follows
1199031 = ℎ1119909119905ξ119875 + 1198991
1199032 = ℎ2119909119905ξ119875 + 1198992 where
56
119945120783 and 119945120784 are the channel gain associated with the
small-scale fading from the BS to users 119932120783 and 119932120784 respectively
1199511 and 1199512 are the additive white Gaussian noise with zero mean and variance
119925120782
Step 4 the BS transmit signal-to-noise ratio (SNR)
120646 = 119927119925120782
Step 5 Signal-to-Interference-plus-Noise-Ratio (SINR) for the two users 119932120783
decodes the signal of the weak user first then decodes its own signal after using
SIC 119932120784 is an untrusted user and tries to decode the near user message after
decoding its own message using SIC
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588ൗ and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ2ȁ2+1120588ൗ and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2
119879119900119905119886119897119904119894119899119903 = ሼ11987811986811987311987721 1198781198681198731198771
1 11987811986811987311987722 1198781198681198731198771
2ሽ
where 119930119920119925119929119950119951
is the signal-to-interference-plus-noise-ratio (SINR)
of user 119950th decoded by 119932119951 for 119898 119899120598ሼ119894 2ሽ and ȁ119945119950ȁ2 is the
channels gain of 119932119950
Algorithm II
Partially observable Markov decision process
Step 1 Prediction of the maximum capacity of channel with respect to the data rate
119955119943 = 119877(119878119909119863)
S is denoted as states
Let D be the channel characteristics which are considering here as actions
Reward function R
Step 2 The agent receives an observation 119900120598120118which depends on the new state of
the environment 119930prime and on the just taken action 119941 with probability
119926(119952ȁ119956prime 119941)
Step 3 Reward earned at time t is expressed as
57
119903119891119905 = 119877(119878119909119863)119905
Step 4 reward function on belief states
119919 is the belief states over POMDP states
119919119943 is the belief state transition function
119955119943 = 119877(119867119909119863)
Step 5 The reward function is updated based on the belief MDP the agent only
cares about which action will yield the largest expected immediate reward ie the
maximum capacity channel
119861119891 ቀℎ 119889 ℎprimeቁ = 119875119903 (
119900120598120118
ℎprimeȁℎ 119889 119900) 119875119903(119900ȁ119889 ℎ) 119861119891
119875119903(ℎprimeȁℎ 119889 119900) = ቄ1119894119891119905ℎ119890119887119890119897119894119890119891119906119901119889119886119905119890119908119894119905ℎ119886119903119892119906119898119890119899119905119904ℎ 119889 119900119903119890119905119906119903119899119904ℎprime
0119900119905ℎ119890119903119908119894119904119890
119903119891(ℎ 119889) = σ ℎ(119904)119877(119904 119889)119904isin119878
34 SUMMARY
The NOMA-UAV communication framework has been proposed in this research
work and the Physical Layer security aspect has been focused on for optimization
The PLS performance metrics selected are SOP amp Pair OP in the proposed system
model The POMDP framework is general enough to model a variety of real-world
sequential decision-making problems Applications include robot navigation
problems machine maintenance and planning under uncertainty in general Here
we have adopted the User pairing POMDP algorithm for resource allocation in two
users amp multi-user NOMA-UAV communication networks The proposed study has
been evaluated using performance measures by varying distances of trusted amp
untrusted users from the base station as well as for varying SINR conditions The
simulation results and outcomes are discussed in a further chapter
58
CHAPTER 4
RESULT AND DISCUSSION
41 PERFORMANCE MEASURES OF SECURED NOMA-
UAV COMMUNICATION MODEL
Drones or UAV-based communication technology has been thoroughly studied and
adopted by the 3GPP standard UAV systems have been envisaged to form an
integral part of future wireless communication applications due to their dynamic
flexible and flying nature Due to their ability to reach higher altitudes they usually
have dominant LOS channels with the ground nodes This capability can be used to
provide confidentiality to the legitimate receivers against the eavesdroppers This
can be done by deploying UAVs to launch more effective jamming signal attacks
to terrestrial eavesdroppers The conventional cooperative jamming schemes make
an assumption that the locations of terrestrial jammers are fixed which might
compromise the secrecy of the system if the jammers are located far away from the
eavesdroppers and is also not practical as it makes an assumption of perfect CSI of
the jammer to eavesdropper channel
Here in the proposed scenario of the NOMA-UAV communication network two
key PHY layer security metrics SOP amp Pair Outage Probability have been jointly
optimized for a more effective power allocation factor for NOMA cellular
architecture The varying channel characteristics have been analyzed to achieve the
desired SOP with the constrained threshold minimum target secrecy rate for the
two-user scenario POMDP Algorithm iteratively provides the optimized SINR that
has been used to keep trusted users in pair with the untrusted user with minimum
achievable outage probability
The proposed NOMA-UAV System model has been simulated in MATLAB 2019b
version with mainly Communications System Toolbox Optimization Toolbox RF
Toolbox Signal Processing Toolbox Statistics and Machine Learning Toolbox
The simulation has been carried out for two-user pair to achieve desired secrecy
target rate and feasible pairing between trusted user amp untrusted user(eves-dropper)
59
The optimal-outage performance of minimized pair OP subjected to SOP constraint
has been solved by both dynamic programming optimization and POMDP
optimization approaches
The simulation of the proposed framework for the UAV-NOMA communication
network has been carried out and discussed in two parts two user models and a
multi-user model as below mentioned discussion The base station is deployed at
the center of a cell of radius 1000 m There are two users in the system under
consideration The channel between two nodes in the system suffers both the small-
scale fading and path loss effect Small-scale fading follows the exponential
distribution with the mean value 1 The noise signal of all channels has a Gaussian
distribution with 0 mean and variance 1 The path loss exponent α and the path loss
constant PLo are set to 2 and 01 respectively We assume a normalized bandwidth
of 1 Hz The SOP constraint threshold is assumed 01 and the target secrecy rate is
001 The power allocation coefficient is 015 and the BS transmitted SINR is
assumed 15dB for the proposed model As per the NOMA transmission scheme
SINR has been obtained for User 1 amp User 2 both for SIC decoding POMDP
algorithm optimally tunes the SINR value for User 1 amp User 2 that is considered to
select optimal power allocation coefficient for both trusted and untrusted users with
respective SOP of User1
42 Numerical results and Discussion
Table 41 Simulation Parameters
Parameters Values
Untrusted user Distance (d2) 200-1000 (300 700)
BS transmit signal-to-noise ratio (SNR) (120588) in dB 15
Sop constraint constant threshold (β) 01
Power allocation factor (t) 015
Trusted User distance (d1) 2-
60
Cell Radius (rd) 1000 meters
Path loss exponent (α) 2
Path loss constant (PLo) 01
Normalized bandwidth in Hz 1
Target secrecy rate (Rs) 001
No of Bits 100
Pair Outage Probability (P0) 05250
SINR 5319 15305 5162
10247
421 Feasible amp Infeasible pairing of trusted amp Untrusted users
In this section the CSI value broadcasted by Base Station is assumed 15 dB initially
and for varying channel conditions various SINR values of 120646 = minus20 minus10 20 dB
is described with target secrecy rate 0005 and 001 for power allocation coefficient
015 and User 1 distance at 200m is shown in the Figure 41 below
Figure 41 Impact on Sop with increase distance between BS and user U2
61
Varying target secrecy rate threshold from 0005 to 001 the obtained result in
Figure 42 revealed that the 1199321 is a gradually reducing function for the distance of
untrusted user d2 that implies that the increasing value of d2 leads to the
improvement of the SOP of 1198801
Figure42 Impact on Sop with increase distance between BS and user U2
Since the offered constant threshold 120656 in SOP limit1199322 which should be located at
a larger space when compared with a value of threshold to attain the SOP of 1199321
apart from that it is expected the high target secrecy rate maximizes the SOP of 1199321
Here in below figure the power allocation coefficient has been varied from 0 to 1
with threshold value of t and the desired t_sop for feasible pairing
Figure 43 Feasible pairing t Vs pair OP
62
Pair OP in case of rising 1199322 untrusted user in d2 for different BS transfer the SNR
where t= 015 and d1=200mThe infeasible pairing of SOP (1199321) and the OP pair
by the enhanced allocation of the power (t) d1 (200m) d2 (300m) 120646 = 15 dB and
120656 = 0
Figure 44 shows the identical plotting of data by adjusting the unauthenticated
level of the user through converting it to a BS closer distance (d2=300m) Accuracy
is compared and checked with the full spectrum of numerical simulations The
result has shown that the effectiveness is based on a comparative study of the two
consumers of the BS
Figure 44 Infeasible pairing t Vs pair OP
422 The Secrecy Outage Probability amp Pair Outage Probability
Feasible paring in the SOP of pair OP and 1199321 with the improved power allocation
factor t in which d2=700m d1=200m 120646 = 15119889119861 and The result described that
the OP and SOP of the user 1199321 with increased for two various distances of the 1199322
untrusted user The simulation result approves the convex nature 120656 = 0 1of the OP
and the SOP is sequentially decreased depending on t Generally when it enhances
the power owed to the weak user text reduces that develop the ability of 1198802 for
discerning the superior positioned signals therefore enhancing the SOP of 1198801
63
Figure 45 Secrecy outage probability
Figure 46 Pair outage probability
423 SNR versus Strictly Positive Secrecy Rate
Figure 47 proved that the potential for confidentiality is superior to the existing
techniques The proposed application for pre-coding improves the efficiency of the
device The transmission power of the system is the power needed for the
transmission of particular data
64
Figure 47 SNR versus Strictly positive secrecy rate
If there is a growth in the number of users there is a risk of inference in the
transmission of data and thus the reliability of the data rate may be affected Based
on these cases the efficiency of the antenna power to be withheld and occupy the
data determined
424 Power radiated by per MMBs antenna
In the case of multi-users scenario when there are more than two users then the
allocation of an optimized resource block to all users is the key parameter to achieve
desired outage efficiency because strong users require higher SNR for higher data
rates and weak users are allocated minimum threshold SNR for lower data rate
requirements to maintain suitable pairing OP and SOP balance
Figure 48 Power radiated by per MMBs antenna
65
So the POMDP policy optimization has shown better performance over the
dynamic programming approach particularly when more users are active (a greater
number of antennas as in Figure 48 the overall radiated power per BS antenna in
downlink has been considerably reduced
43 CONCLUSION AND SCOPE OF FUTURE WORK
431 Conclusion
Starting with LTE (4G) OFDMA has replaced WCDMA with mobile cellular
communications and will also be used during advanced 5G while Non-Orthogonal
Multiple Access (NOMA) has recently been recognized as a groundbreaking PHY
technology in UAV communication NOMA scheme is used in place to increase the
effective use of small resources such as in UAV communication where the data rate
is very low and critical decision making is of utmost importance
The critical need for UAV communication is a secure PHY layer for mission-
critical applications and as NOMA doesnrsquot promise high security the proposed
research work has been carried out to enhance the insecurities of NOMA-UAV
communication In this proposed research work the probabilities of confidential
outage (SOP) and OP were investigated in the two-user NOMA system Here BS is
required to pair a trusted or permissible user with other untrusted users due to the
unequal distribution of untrusted and trusted users in the cell The SIC is then
applied to the receiver side intended for decoding the message signals The Pair OP
of both users has been analyzed for varying Target Secrecy Rate (Rs) of the trusted
user U1 which provides constraint threshold of the SOP of U1
By varying the distance of Untrusted users from BS the optimal distance and power
allocation factor for the feasible pairing of trusted and untrusted users without
compromising the secrecy outage probability of U1 has been achieved in simulation
results
POMDP has provided the optimal power allocation as a resource allocation
algorithm in the dynamically changing environment of two user NOMA cases
where the distance between BS and untrusted user varies significantly The
performance of secure NOMA-UAV is affected critically by (SOP of User 1) which
66
should be optimally selected to maintain the proposed Pair OP between both users
and the simulation results have supported this optimal outage performance Thus
NOMA-UAV architecture has the potential of providing a secure PHY layer for
mission-critical applications by opting for suitable decision-making resource
algorithm POMDP
431 Scope of Future Work
Furthermore the multiuser scenario with the increased number of Untrusted users
can be analytically verified and simulated in the same direction for NOMA-UAV
communication to improve transmission security and reliability In addition more
adaptive and efficient Resource allocation algorithms for NOMA-UAV networks
with secured performance in real-time applications should be investigated
1
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11
PUBLICATIONS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495449|P a g e
Migration from 4g LTE to Advanced PHY Techniques for
Unmanned Aerial Vehicle (UAV) Communication
Pankaj Patel PHD StudentGujarat Technological UniversityGujarat India
ABSTRACT
UAV (unmanned aerial vehicles) with their high mobility and low cost have found a wide range of applications
during the past few decades Historically UAVs have been primarily used in the military mainly deployed in
hostile territory to reduce pilot losses With continuous cost reduction and device miniaturization small UAVs
are now more easily accessible to the public hence numerous new applications in the civilian and commercial
domains have emerged For the sake of boosting resilience against faults natural disasters and unexpected
traffic the Unmanned Aerial Vehicle (UAV) assisted wireless communication systems can provide a unique
opportunity to cater for such demands in a timely fashion without relying on the overly-engineered cellular
network However for UAV-assisted communication issues of capacity coverage and energy efficiency are
considered of paramount importance Starting with LTE (4G) Orthogonal Frequency Division Multiple Access
(OFDMA) has replaced WCDMA for cellular mobile communications and it will also be employed in advanced
5G yet Non-orthogonal multiple access (NOMA) has been recently recognized as a promising PHY technique
to significantly improve the spectral efficiency of mobile communication networks In this paper we provide an
overview of UAV-aided wireless communications by introducing the basic networking architecture
highlighting the key design considerations as well as the new opportunities to be exploited
Keywords LTE (4G) Non-orthogonal multiple access (NOMA) Unmanned Aerial Vehicle (UAV) Wireless
communication
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Date Of Submission 26-04-2019 Date Of Acceptance 06-05-2019
----------------------------------------------------------------------------------------------------------------------------- ----------
I INTRODUCTION The use of unmanned aerial vehicles
(UAVs) will grow rapidly in the next decade These
remotely piloted or preprogrammed aircraft are
envisioned for applications in numerous civil
settings including industrial monitoring scientific
data gathering agriculture public safety and search
and rescue Many other applications - presently
unforeseen - will inevitably also arise These
vehicles also known as the unfortunate misnomer of
drones must be integrated into the national
airspace system and into the airspace worldwide A
natural concern in the use of UAV is safety and this
has direct implications for the control and non-
payload communication systems that must be used
to operate it efficiently Similarly navigation and
surveillance functions must be made more reliable
and more accurate Because of these factors many
UAV research development testing and
standardization efforts are underway by
governments industries and academia Despite the
fact that piloted civil aircraft have been flying safely
for decades UAV presents distinct new challenges
in the form of different flight profiles eg low-
elevation flights and more high-dynamic maneuvers
wider required bandwidths eg for video and
different ground site characteristics such as locations
in cluttered areas and lower elevation antennas
In this paper first the evolution of radio
technologies considered in UAV wireless
communication is reviewed in literature survey and
the significant work in the area is highlighted along
with the newest challenges The reminder of this
paper is organized as follows
The promising technology NOMA and its
variants are discussed in section three In Section
four the system model and assumptions are
presented and in section five the comparative
analysis of NOMA with existing popular technology
OFDMA (OMA) is given with simulation
persormance analysis At last the work is concluded
in section five
II LITERATURE SURVEY Drones variously known as unmanned
aerial vehicles (UAVs) unmanned aerial systems
(UAS) or remotely piloted aircraft system (RPAS)
are used in several parts of the world for surveying
and aerial mapping disaster management work
monitoring crop production and infrastructure
activities besides commercial photography and
courier delivery The viability of UAV as a
multipurpose research vehiclehas driven great
RESEARCH ARTICLE OPEN ACCESS
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interest since recent decades[1] The
basictechnology building blocks responsible for the
current advancesinclude airframes propulsion
systems payloadssafety or protection systems
launch and recovery dataprocessor ground control
station navigation and guidanceand autonomous
flight controllers The following briefsurvey is
focused on the area of navigation guidance
andcontrol of UAVs Various control design for
UAVs has beenproposed ranging from linear to
nonlinear synthesis timeinvariant to parameter
varying and conventional PID tointelligent control
approaches The developed controllershave been
implemented for different aerial platforms
airship(blimp) fixed-wing UAV small scale
helicopteruad-rotors and MAV Wireless
communication systems that include unmanned
aerial vehicles promise to provide cost-effective
wireless connectivity for devices without
infrastructure coverage Compared to terrestrial
communications or those based on high-altitude
platforms on-demand wireless systems with low-
altitude UAVs are in general faster to deploy more
flexibly reconfigured and likely to have better
communication channels due to the presence of
short-range line-of-sight links However the
utilization of highly mobile and energy-constrained
UAVs for wireless communications also introduces
many new challenges In India for the regulation
and safety purpose in commercial and survilence
applications the policy guideliens also introduced
as below
Table 1UAV communication Policy Guidelines for
commercial and surveillance purpose
III MIGRATION FROM 4G LTE TO 5G The fruitful deployment of UAV based
communicationsystems for 4G and beyond future
wireless networks is highlyinvolved in finding joint
solutions to challenge of ubiquitousconnectivity with
both a multitude of devices in a spectralefficient way
as well as with energy-efficient transmissionand
operation of the UAV-BS for maximized and
armonizedcoverage and capacity [2][3] It should be
noted that suitableenergy efficiency for the UAV-
assisted ommunication systemachieves paramount
importance in the overall performance ofthe system
Efficient energy consumption results in
enhancedairtime for the communication system
improving bitsJoulesfor a given energy level
Furthermore coverage and capacityof an aerial cell
are attributed to many factors such as
thetransmission power antenna gains UAV
altitude deploymentenvironment and prominently
radio access technology [4]
4G is the fourth generation of broadband
cellular network technology succeeding 3G and
besides the popular techniques in 3G4G ie
TDMAWCDMAOFDMA a new radio access
technology NOMA is also developed by researchers
to be used in communication networks due to its
capability in increasing the system capacity
Recently non-orthogonality based system designs
are developed to be used in communication
networks and have gained significant attention of
researchers Hence multiple access (MA) techniques
can now be fundamentally categorized as orthogonal
multiple access (OMA) and non-orthogonal
multiple access (NOMA) In OMA each user can
exploit orthogonalcommunication resources either
within a specific time slot frequency band or code in
order to avoid multiple access interference The
previous generations of networks have employed
OMA schemes such as frequency division multiple
access (FDMA) of first generation (1G)time
division multiple access (TDMA) of 2G code
division multiple access (CDMA) of 3G and
orthogonal frequency division multiple access
(OFDMA) of 4G
In NOMA multiple userscan utilize non-
orthogonal resources concurrently by yielding a high
spectral efficiency while allowing some degree of
multiple access interference at receivers Recently
NOMA reputations have climbedsharply as a
fundamental solution to the challenges
encompassingthe next generation wireless networks
[5][6]NOMA has been proved to exhibit improved
spectral efficiencybalanced and air access as
compared to OMAtechnologies[6] with the ability
to cater for multipledevices in the same frequency
time or code resource thusproviding efficient access
to massive connected devices Furthermore NOMA
is also instrumental in reducingthe interference by
employing orthogonal resources as inOrthogonal
Frequency Division Multiple Access
(OFDMA)[7][17] or by sharing a single beam
between multiple users forintra-cluster access and
using NOMA for inter-cluster access[18]Current
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studies have focused on provisioning Air to
Ground(A2G) communication services mainly
through placement op- timization under various
viewpoints in literature The performance of UAV
based communication systems hasalso been
addressed for the underlaid Device to Device(D2D)
deployment scenario This work assumed
interferenceraised by D2D network nodes without
considering the presenceof terrestrial BS
Additionally there have been a fewstudies
discussing the performance of NOMA for UAV
basedcommunication system[8] A NOMA enabled
fixedwingUAV deployment was proposed in [8] to
support coveragefor ground users situated outside
BS offloaded location
In general NOMA schemes can be
classified into two types power-domain
multiplexing andcode-domain multiplexing In
power-domain multiplexing different users are
allocated[7][8][9][6][5][1][10] differentpower
coefficients according to their channel conditions in
order to achieve a high systemperformance In
particular multiple usersrsquo information signals are
superimposed at the transmitterside At the receiver
side successive interference cancellation (SIC) is
applied for decoding thesignals one by one until the
desired userrsquos signal is obtained providing a good
trade-offbetween the throughput of the system and
the user fairness In code-domain multiplexing
different users are allocated different codes and
multiplexed over the same time-frequencyresources
such as multi-user shared access (MUSA) sparse
code multiple access (SCMA) and low-density
spreading (LDS) In addition to power-domain
multiplexing and codedomain multiplexing there are
other NOMA schemes such as pattern division
multiple access(PDMA) and bit division
multiplexing (BDM) Although code-domain
multiplexinghas a potential to enhance spectral
efficiency it requires a high transmission bandwidth
andis not easily applicable to the current systems
On the other hand power-domain multiplexinghas a
simple implementation as considerable changes are
not required on the existing networksAlso it does
not require additional bandwidth in order to improve
spectral efficiency Inthis paper the prime focusis on
the power-domain NOMAAlthough OMA
techniques can achieve a good system performance
even with simple receiversbecause of no mutual
interference among users in an ideal setting they
still do not have theability to address the emerging
challenges due to the increasing demands in future
networks andbeyond
The superiority of NOMA over OMA can
besummarized as follows
_ Spectral efficiency and throughput In OMA such
as in OFDMA a specific frequencyresource is
assigned to each user even it experiences a good or
bad channel conditionthus the overall system suffers
from low spectral efficiency and throughput In
contrary inNOMA the same frequency resource is
assigned to multiple mobile users with good and
bad channel conditions at the same time Hence the
resource assigned for the weak user isalso used by
the strong user and the interference can be mitigated
through SIC processesat usersrsquo receivers Therefore
the probability of having improved spectral
efficiency and ahigh throughput will be considerably
increased
_ User fairness low latency and massive
connectivity In OMA for example in OFDMAwith
scheduling the user with a good channel condition
has a higher priority to be servedwhile the user with
a bad channel condition has to wait to access which
leads to a fairnessproblem and high latency This
approach cannot support massive connectivity
HoweverNOMA can serve multiple users with
different channel conditions simultaneously
thereforeit can provide improved user fairness lower
latency and higher massive connectivity
_ Compatibility NOMA is also compatible
with the current and future communication
systemssince it does not require significant
modifications on the existing architecture For
exampleNOMA has been included in third
generation partnership project long-term
evolutionadvanced (3GPP LTE Release 13)
Figure 1Pictorial comparison of NOMA Vs OMA
Although NOMA has many features that
may support next generationsit has some limitations
that should be addressed in order to exploit its full
advantage set Thoselimitations can be pointed out
as follows In NOMA since each user requires to
decode thesignals of some users before decoding its
own signal the receiver computational
complexitywill be increased when compared to
OMA leading to a longer delay Moreover
informationof channel gains of all users should be
fed back to the base station (BS) but this results in
asignificant channel state information (CSI)
feedback overhead Furthermore if any errors
occurduring SIC processes at any user then the error
probability of successive decoding will beincreased
As a result the number of users should be reduced to
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avoid such error propagationAnother reason for
restricting the number of users is that considerable
channel gain differencesamong users with different
channel conditions are needed to have a better
network performance
IV NOMA UPLINK AND DOWNLINK
SCENERIO SIMULATION ANALYSIS In this section an overview of NOMA in
downlink and uplink networks is introduced
throughsignal-to-interference-and-noise ratio (SINR)
and sum rate analyses Then high signal-to-
noiseratio (SNR) analysis has been conducted in
order to compare the performances of OMA
andNOMA techniques[10]
A Downlink NOMA Network
At the transmitter side of downlink NOMA
network as shown in Fig 2 the BS transmits
thecombined signal which is a superposition of the
desired signals of multiple users with different
allocated power coefficients to all mobile users At
the receiver of each user SIC process isassumed to
be performed successively until userrsquos signal is
recovered Power coefficients ofusers are allocated
according to their channel conditions in an inversely
proportional mannerThe user with a bad channel
condition is allocated higher transmission power
than the one which has a good channel condition
Thus since the user with the highest transmission
power considers the signals of other users as noise
and recovers its signal immediately without
performing anySIC process However other users
need to perform SIC processes In SIC each userrsquos
receiverfirst detects the signals that are stronger than
its own desired signal Next those signals
aresubtracted from the received signal and this
process continues until the related userrsquos own signal
is determined Finally each user decodes its own
signal by treating other users with lower
powercoefficients as noise The transmitted signal at
the BS can be written as
s = aiPsxi
L
i=1
where xi is the information of user i (Ui)
with unit energy Ps is the transmission power atthe
BS and ai is the power coefficient allocated for user
i subjected to ai = 1Li=1 and a1gea2gehellip geaL since
without loss of generality the channel gains are
assumed to be ordered as h1 2 le h2 2 le⋯ hL 2 where hL is the channel coefficient of Lth
user based on NOMAconcept The received signal
at lth user can be expressed as follows
y1 = hls + nl = hl aiPsxi + nlL
i=1
where nlis zero mean complex additive Gaussian
noise with a variance of σ2
(1) SINR analysis By using (2) the instantaneous
SINR of the lth user to detect the jth user jle l
with jne L can be written as
SINRl = alγ hl 2
γ hl 2 aiLi=l+1 + 1
Where γ = Psσ2 denotes the SNR
(2) Sum rate analysis After finding the SINR
expressions of downlink NOMA the sumrate
analysis can easily be done The downlink
NOMA achievable data rate of lth user can
beexpressed as
RlNOMA-d
= log2 1 + SINRl = log2(1 +alγhl2γhl2 i=l+1Lai+1
B Uplink NOMA Network
In uplink NOMA network as depicted in
Fig 3 each mobile user transmits its signal to the
BS At the BS SIC iterations are carried out in order
to detect the signals of mobile users By assuming
that downlink and uplink channels are reciprocal and
the BS transmits power allocation coefficients to
mobile users the received signal at the BS for
synchronous uplink NOMA can be expressed as
r = hi aiPxi + n
L
i=1
where hi is the channel coefficient of the ith
user Pxi is the maximum transmission power
assumed to be common for all users and n is zero
mean complex additive Gaussian noise with a
variance of σ2
Figure 2Downlink NOMA network
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Figure 3 Uplink NOMA network
1) SINR analysis The BS decodes the signals of
users orderly according to power coefficientsof
users and then the SINR for lth user l ne 1 can
be given by
SINRl =alγ hl 2
γ ai hi 2 + 1lminus1i=1
where γ =P
σ2
2) Sum rate analysis The sum rate of uplink
NOMA when γ minus infincan be written as
Rsum NOMA-u asymp log2(γ hl 2L
l=1
C Comparing NOMA and OMA
The achievable data rate of the lth user of OMA for
both uplink and downlink can be expressed
RsumOMA = αl log2(1 +
βlγ hl 2
αl)L
l=1
For the sake of simplicity sum rates of
uplink NOMA and OMA can be compared for
twousers Then using both the sum rate of uplink
NOMA and OMA at high SNR can beexpressed
respectively as
RsumNOMAasymp log2 γ h1 2 + γ h2 2
Here we notice ROMA
sumle RNOMA
sum
Fig shows that NOMA outperforms OMA in terms
of sum rate in both downlink and uplinkof two
user networks
V SIMULATION RESULTS
The Comparative analysis of modelling
Downlink and Uplink NOMA in comparison with
OMA is simulated and findings are presented that
shows superiority of NOMA over OMA with better
spectral efficiency for simulation parameters taken
as power allocation coefficients a1=06 a2=04 and
channel responses h1 2
=0 DB h22=20 DB
parameters
Figure 4NOMA UPLINK
Figure 5 NOMA DOWNLINK
VI CONCLUSION This paper investigated an account of
NOMArsquos applicability for UAV-assisted
communication systems NOMA schemes are
proposed to improve the efficient usage of limited
network sources OMA based approaches that use
time frequency or code domain in an orthogonal
manner cannot effectively utilize radio resources
limiting the number of users that can be served
simultaneously In order to overcome such
drawbacks and to increase the multiple access
efficiency NOMA technique has been recently
proposed Accordingly users are separated in the
power domain Such a power domain based multiple
access scheme provides effective throughput
improvements depending on the channel conditions
The crucial need of UAV communication of
optimum utilization of available licensed spectrum
bandwidth is considered here and simulation results
taken presented that NOMA performs better than
OMA while fulfilling individual user-rate constraint
for both users The research work can be further
carried out investigating joint power and phase
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allocation of UAV nodes deployment for efficient
operations
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Non-Orthogonal Multiple Access for Unmanned
Aerial Vehicle Assisted Communication in IEEE
access 2018
[2] M Mozaffari Drone small cells in the clouds
Design deployment and performance analysis in
IEEE Global Communications Conference 2015
[3] R Z a T J L Y Zeng Wireless
communications with unmanned aerial vehicles
opportunities and challenges in IEEE
communication magazine 2016
[4] I B-Y a H Yanikomeroglu The new frontier in
ran heterogeneity Multi-tier drone-cells IEEE
Communications Magazine pp 48-55 2016
[5] P K S a D I Kim Uav-enabled downlink
wireless system with NOMA access in IEEE
Globecom Workshops Dec 2017
[6] P Xu and K Cumanan Optimal power allocation
scheme for nonorthogonal multiple access with
fairness in IEEE Journal on Selected Areas in
Communications oct 2017
[7] E H a D I K S Ali Non-orthogonal multiple
access (noma) for downlink multiuser mimo
systems User clustering beamforming and power
allocation in IEEE Access 2017
[8] W S M B a M D M Mozaffari Unmanned
aerial vehicle with underlaid device-to-device
communications Performance tradeoffs in IEEE
Transactions on Wireless Communications June
2016
[9] Z D X D a R Z Z Chen An optimization
perspective of the superiority of noma compared to
conventional oma in IEEE Transactions on
Signal Processing Oct 2017
[10] M T Mahmoud Aldababsa1 and S G G K 2 A
Tutorial on Non-Orthogonal Multiple Access
2017
[11] X L Z J W a K J R L Zhu Han Delay
Sensitive Scheduling Schemes for Heterogeneous
QoS over Wireless Networks IEEE
TRANSACTIONS ON WIRELESS
COMMUNICATIONS VOL 6 NO 2
FEBRUARY 2007 vol 6 no 2 2007
[12] Z J W a K J R L Z Han A resource
allocation framework with credit system and user
autonomy over heterogeneous wireless networks
in IEEE Global Telecommunications Conference
2003
[13] N B S a P S S Chen Heterogeneous delay
tolerant task scheduling and energy management in
the smart grid with renewable energy IEEE
Journal of Selected Areas in Communications vol
31 no 07 pp 1258-1267 july 2013
[14] H L Z C a Z H Y Hu Scheduling strategy for
multimedia IEEE Transactions on Vehicular
Technology July 2016
[15] P F a K B L Y Dong High-speed railway
wireless communications efficiency vs fairness
IEEE Transactions on Vehicular Technology vol
63 no 2 pp 925-930 march 2014
[16] T R a Z H Z Chang Queueing game for
spectrum access in cognitive radio networks
IEEE Communications Letters vol 19 no 11 pp
2017-2020 June 2015
[17] Z C L T R a Z H F I Yun Hu Service
Provisioning and User Association for
Heterogeneous Wireless Railway Networks IEEE
Transactions on Communications 2017
[18] H S W Tianti Chen Optimal Scheduling for
Wireless On-Demand Data Packet Delivery to
High-Speed Trains IEEE Transactions on
Vehicular Technology vol 64 no 9 pp 4101 -
4112 september 2015
Pankaj Patel Migration from 4g LTE to Advanced PHY Techniques for Unmanned Aerial
Vehicle Communication International Journal of Engineering Research and Applications
(IJERA) Vol 09 No04 2019 pp 49-54
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Improving Of Physical Layer Insecurity Of The
Non Orthogonal Multiple Access System
Pankaj M Patel Prof Dr Chetan B Bhatt
Abstract The key aspect of the NOMA (power domain non orthogonal) is the user possibility for decoding the messages belonging to another pair users
on similar resources The method interprets a security threat especially in the case where the base station serves the users with various security
clearance or untrusted users The main aspect of NOMA is to serve the multiple users upon the similar radio resources at the minimal inter user
interference expense The system not only permits the serving of particular users with high efficient bandwidth but also permits the scheduling more type
of users than the timely available users In this study we investigated the secrecy outage probability (SOP) and OP in the both two user and multi user
NOMA system where the BS is supposed to pair a trusted or legitimate user with other untrusted users because of the un even distribution of the
untrusted and trusted users in the cell SIC the successive interference cancellation was then implemented at the receiver side for decoding the
message signals With the application of NOMA concept the study investigated the pair outage behavior under the SOP constraints on the trusted users
In specific the SOP and OP of the concerned U1 were obtained in the closed type of expressions The study also provided the understanding the
possibility of obtaining an optimal outage efficiency for pairing under the SOP constraints With certain numerical simulations the study verified the
effectiveness of the analytical derivations with respect to various scenarios
Index Terms NOMA Secrecy outage Probability Successive Interference Cancellation bandwidth channel state information etc
mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash
1 INTRODUCTION The physical layer security and non-orthogonal multiple
access was regarded as the encouraging techniques for the
processing of wireless communication network systems Today
the combination of the two significant communication methods
was studied to guarantee a spectral efficient and secure
wireless transmission Most of the prevailing works
predominantly concentrated on the optimization and efficiency
of the PLS in the existence of untrusted relay nodes and
external eavesdroppers(Arafa et al 2019a)But there occurs a
gap in the theoretical studies to describe the ease of obtaining
the enhanced efficiency in the existence of untrusted users
Recently the network traffic amount have greatly enhanced
particularly with the updated growth in IoT applications in
future To rectify the huge traffic demand upcoming wireless
networks must deliver a best spectral effectiveness and large
connectivity (Sun et al 2018) NOMA is regarded as the best
technology in which various NOMA technique exhibit similar
concept of providing several users at the similar frequency and
time The famous NOMA types are code domain and power
domain that provided enhanced efficiency when compared
with the existing techniques The paper adopted the power
domain on the basis of super position coding (transmitter side)
at the SIC (receiver side) Hence the users could possess the
key for the messages of other users and thereby utilize SIC for
removing the interference (Cao et al 2019) (Zhao et al
2018) Hence various NOMA methods was proposed for
allowing the adjacent users to perform as a relay for improving
the efficiency of the weak users through the resending of
decoded data in a next time slot The weak user could utilize
the MRC technique to integrate the information achieved in
different time slots In addition obtaining a secured
communication is a crucial problem over the vulnerable
wireless networks to security threats mainly because of the
broadcasted transmission nature
The study investigated the secrecy performance and outage
with the untrusted user(Furqan et al 2019) The main aspect
of the study is to analyze the feasibility of achieving the OP of
the pair under a trusted user Because of the decoding facility
and spectrum sharing of SIC the untrusted user could perform
as a eavesdropper
Figure 1 Representation of Base station
Figure 1 depicts the representation of base station The main
aim of the proposed system defined as
bull To investigate the outage probability of the proposed
system
bull To investigate the SOP of the proposed system
bull To derive the accurate expression of the outage
probability for all kind of scenarios and closed form of
expressions for few special cases and verifying them
numerically for yielding a better outage efficiency
2 RELATED WORKS This section describes the different existing techniques and
methods related as our proposed system (Cao et al
2019)suggested two kinds of relay selection process denoted
as AF (amplify and forward) and DF (decode and forward) on
the basis of AORS and DORS for achieving secure and
reliable NOMA systems under the untrusted users The study
derived the accurate and asymptotic closed form of the SOP
expressions and the PSCP obtained by the two methods and
investigated the optimized feature of the two methods The
____________________________________
bull PANKAJ M PATEL is currently pursuing PHD program in Electronics
amp Communication in Gujarat Technological University E-mail
pankajmphd24gmailcom
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complete analysis and the simulation results represented that
both the AORS and DORS characteristically outperformed the
benchmark system apart from obtaining the similar SOP and
the required PSCP at very high Signal to noise ratio (Zhang et
al 2018)Investigated the power allocation and joint subcarrier
issue for NOMA ndashAF two-way relay networks with restrictions
The study focused to optimize the obtainable secrecy
efficiency by designing jointly the SC task power allocation
and user pair scheduling The paper suggested a SCAS-1
technique by assuming the appropriate information about the
channel state information in the relay station followed by the
formulation of SCAS-2The secured power allocation issue is
structured as a convex programming issue and then resolved
by in-depth point techniques The results of simulation
explained that the efficiency of the suggested SSPA algorithms
with and without CJ respectively (Arafa et al
2019b)Considered a downlink system where the base station
is connecting with two appropriate users in two various
scenarios in the unsecured environments which are the
presence of the eavesdropper and untrusted relay
communication In the first process several trusted
cooperative relays is engaged for assisting with the base
station transmission and protect the corresponding signals
from the eavesdropper Several relay methods are framed and
investigated for the following process which are forward and
decode cooperative jamming and AFFor all the technique
secured beam forming signals were formulated at the relays
for maximizing the obtainable secret rate areas For the next
process with untrusted relay the obtained secrecy rate areas
obtained for two various relay schemes which are AF and CF
under two various operation modes In the first process the
prescribed users will receive the signals from the untrusted
relay and the base station for decoding the messages The
study depicted that the efficient relay scheme is highly
dependent on the parameters of the system especially the
nodal distance and the secrecy rate area (Sun et al
2018)Studied the algorithm for resource allocation for MISO
systems where the full duplex BS serve several half duplex
downlink and uplink users on the similar subcarrier The
allocation of the resource have been optimized for maximizing
the weight system output whereas the leakage of information
was restricted and an artificial noise was induced for granting
secured communication with respect to potential
eavesdroppers The study formulated a novel non-convex
optimization issue by considering the imperfect CSI of the
channels and requirements of QoS of legitimate users The
simulation results stated the efficiency of the optimal algorithm
was related to the suboptimal algorithm Apart from that the
suggested MISO NOMA technique not only guarantee uplink
and downlink communication purpose for security but delivers
a characteristic rate of system secrecy when compared with
the conventional MISO and other two baseline methods
(Dang et al 2017)Analysed the outage efficiency of various
multicarrier relay selection techniques for 2 hop OFDM system
in Poisson relay fields The study concentrated on DF relay
systems with more selection schemes The accurate
expressions for the OP are provided in integrals generally
Apart from that asymptomatic derivatives for OP in the SNR
region in the fixed circle area are predicted for both relay
selection techniques in closed forms Consequently several
significant factors that are linked to the cooperative network
were examined comprising OP ratio of two selection
techniques diversity and subcarrier optimization output In
conclusion a structure to analyze the OP of OFDM with
spatially random relay have been constructed that could be
easily altered for analyzing same case with various forwarding
protocols channel conditions and location distributors (Dang
et al 2018)Proposed a full duplex OFDM ndashD2D system in two
hop network where DF relays help the transmission from DUE
transmitter to DUE receiver The study also investigated the
OP issue by integrating the transmit power within the DUE
relays and transmitter and to deliver a suboptimal solution that
can improve the outage performance The investigations are
validated by Monte Carlo simulations These results described
could furnish an insight into full duplex OFDM system and
guides for the application in the next generation network
(Kokshoorn et al 2016) suggested a robust channel algorithm
for mmWave systems on the basis of novel overlapped pattern
design With the use of finite measurements the study
depicted that this decreased measurements was found ENR of
25 dB to obtain the similar PEEFor the appropriate channel
with quickly altering channel information the price might be
acceptable for improving the speed of estimation The study
also proposed a robust channel estimation algorithm where
the additional calculations are carried out when expecting
more estimation error The study depicted that the channel
could be measured more effectively resulting in noteworthy
gains upto 6 dB when comparing with the existing algorithm
(Ali et al 2016) described the variations in the principles of
downlink and uplink NOMA transmissions in a wireless
system The study formulated a maximization issue in a cell
like the user clustering and power allocations Because of the
integral nature of the formulated programming issue the study
solved the issue in to steps which are grouping of users into
clusters and then to optimize the corresponding power
allocations The study proposed a sub optimal scheme that
exploited the gain variations in NOMA groups and clusters into
multiple and single clusters for enhancing the sum-throughput
The results compared the efficiency of OMA and NOMA in
different network scenarios (Lv et al 2017) investigated a
MCR-NOMA where the multicast user functions as relays to
enhance the efficiency of both secondary and primary
networks On the basis of the available CSI three various
secondary user schedule techniques for processing MCR-
NOMA were depicted For evaluating the system efficiency the
study derived the closed form of expressions of OP and order
of diversity for both the networks It has been described that
more spatial temporal diversity could be obtained by using the
CSI for scheduling of the secondary user (Liu et al 2016)
considered a MIMO ndashNOMA scenario for investigating a
dynamic clustering issue in an logical perspective To resolve
the problem of optimization issue three algorithms named top
down A and B bottom up were suggested for realizing various
complexity tradeoff and worst user throughput The study
noted that the top down B algorithm could obtain a better
tradeoff between throughput and complexity amongst the
applied procedures (Fianu and Davis 2018) investigated
three various rules of allocation and demonstrated the optimal
policy as an available inventory function The study also
provided the country level estimation of requirements that are
not met and the determination of the probability distribution
linked with the total undeserved counties The study have
been done for depicting the policy of allocation with respect to
effectiveness and equity (Hou et al 2018) studied the socio
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graphical impact on the mobile video services and thereby
suggested a CTMDP on the basis of resource allocation
technique by considering social graphs as the constraints
With the use of relative value an optimized policy could be
achieved that aimed at increasing the reward regarding the
average system The simulation depicted that the suggested
CTMDP obtained an increased efficiency against the state of
art methods
3 PROPOSED WORK
Fig 2 Proposed flow depicting the overall mechanism
The proposed(Interference mitigation using POMDP) overall flow
is depicted in the figure 2 After setting up of the base station the
distance between the base station and the user was determined
and if the distance is less than 200 meters it is decided as trusted
users and if it is greater than 200 m it is defined as untrusted
users In case of untrusted users the channel state information is
subjected to POMDP (Partially observable Markov Decision
Process) followed by resource allocation The performance
analysis have been done after the system The work considered
a NOMA oriented cellular setup provided with a base station at
the centre and two users as shown in the figure 2 The adjacent
(near) user possess high level of security clearance that is
required for securing with physical layer from the low
securityuntrusted clearance user (U2) that is located at a faraway
distance from the base station P is defined as the maximum
transmit power level (base station)In this paper it is assumed that
all the network nodes are installed with single antenna and further
all the channels are considered to be identical independently
quasi static with Rayleigh distribution with respect to distribution
119862119873(0 120575 frasl
120596 frasl
) In which 120575 is the distance in-between the BS
and nodes 119880 Here path-loss exponent and path-loss constant is
represented as 120572 and 120596 In addition it is assumed that base
station predicted the user location so that a better CSI is
obtainable at base station that is involved in pairing the users
The base station transmits the superimposed mixture
119909 = radic119905 119904 + radic1 minus 119905 119904
In which 119904 119904 are the unit power signals received by users 119880 and
119880 respectively 119905 is the power
allocation coefficient for the adjacent user
119903 = ℎ 119909 radic119875 + 119899
119903 = ℎ 119909 radic119875 + 119899
where ℎ ℎ - the channel gain linked with the
small-scale fading from the base station to users 119880 and 119880
respectively 119899 and 119899 are the extra white Gaussian noise with
variance and zero mean 1198730 and it is assumed that 120588 = 1198751198730 is
the BS convey signal-to-noise ratio (SNR) In NOMA technique
farther user that possess more power
could decode its own signal by considering the adjacent signal as
a noise without decoding the adjacent user message In the
preceding equation it is assumed that U1 first decode the weak
signal followed by decoding its own signal with SICU2 which is
the untrusted user attempted to decode the near user message
after the decoding of the adjacent user messages after the
process of decoding its own message with SICHence the
following equation have been achieved
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119879119900119905119886119897 = 119878119868119873119877 119878119868119873119877
119878119868119873119877 119878119868119873119877
+
where 119878119868119873119877 represented the signal-to-interference-plus-noise-
ratio of user 119898 that was decoded by 119880 for 119898119899120598119894 2+ and the
channels gain of 119880 denoted by |ℎ |
followed an exponential distribution
with the parameter 120577 = 120596 120575
Problem Formulation
Hence the base station should achieve and serve a better
communication for the users who are susceptible to security
threat from untrusted user the proposed system defined two
kinds of QoS efficiency measures that could be regarded to be
important for framing the issue In specific the study defined a pair
of OP to check the reliability of the QoS satisfaction In general
the pair OP is stated as the probability in which the obtainable
data rates dor the users equal to or greater than the least target
threshold The next metric also called as the SOP is the
probability that the non negative secrecy capacity obtained by the
trusted user is more than the threshold value
The following issue aimed at reducing the pair OP subjected to a
SOP factor for the user U1 that is provided by
min
119875
0 lt 119905 lt 05
119878119874119875 le 120573
in which 119875 119878119874119875 and 120573 are the pair OP SOP(119880 ) and the
permissible SOP threshold
4 PERFORMANCE ANALYSIS
Derivation of the Pair OP
With the use of Shannonrsquos capacity formula and considering
119862 and 119862
as the threshold capacities of users 119880 and
user 119880 respectively the OP of the pair could be provided
by
119875 = 1 minus 119876 119909119876
in which
120591 = 2
119898 120598 119894 2+
120601 =
( )
120601 =
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119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 1 120601 gt 120601
For having 120601 gt 120601 the constraint on
the power allocation factor (t) needs to be satisfied
(119905 gt
) and for this case 119876 could be obtained as
follows
119876 = exp (
)
lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 2 120601 lt 120601
Like case 1 it was stated that opposite constraint on
a as (119905 lt
) and
119876 can be derived as follows
119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
The OP of the NOMA pair
119875 = 1 minus 119891(119905)119896 (119905)
lt 119905 lt
1 minus 119891(119905)119896 (119905) 0 lt 119905 lt
in which
119891(119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
Derivation of SOP of 119880
With Shannonrsquos capacity formula the secrecy rate of
user 119880 was provided by
119878119862 = 119869 minus 119869
119869 = log (1 + 119879119900119905119886119897 (r (1)))
119869 = log (1 + 119879119900119905119886119897 (r (2)))
119878119862 is the non-negative secrecy capacity of 119880 Provided the
secrecy capacity in the SOP of 119880 is
119878119874119875 = 1 minus 120584119890
119860 =
120584 =
119879 - the user 119880 secrecy target rate
Theorem 1
Outage-optimal power allocation factor
119905 = radic
( )
In which 119908 =
119908 =
119911 = 1 + 120591
The minimum power allocation factor (119886 )
119905 =
(
)
The optimal OP of the NOMA pair under the SOP constraint
=
( )
( ( ))119890
( )
That is lt 0whih meant that the U1 (SOP) is a reducing function
Of t that results in the optimal power allocation factor that is
greater than 119905 for the satisfaction of secrecy constraining
factorPartially observable Markov decision process S is
represented as statesLet D is the channel features which is
consider here as actions the conditional transition probability
between states is regarded as T Reward function R is
calculated as the prediction of maximum capacity channel with
respect to data rate r = R(S x D) the agent receives an
observation o ϵ 120118 o isin Ω display style oin Omega that
depended on the new environment state S and on the just
took action d with the probability O(o|s d)
Reward received at time t is conveyed as r = R(S x D)
H is the belief states over POMDP states
119867 is the belief state transition function
119903 = 119877(119867 x 119863) is the reward function on the belief states
119861 (ℎ 119889 ℎ ) = sum Pr ( 120118 ℎ |ℎ 119889 119900) Pr(119900|119889 ℎ)
Pr(h |h d o) =
1 if the belief update with arguments h d o returns h 0 otherwise
The reward function is updated on the basis of the belief MDP
r (h d) = sum h(s) R(s d) isin
the agent focus on the largest expected immediate rewardin
other words the maximum capacity channel The section
analyse the accuracy of the analytical derivations under
various settings
Figure 3 The feasible pairing
The SOP of U1 with the increasing untrusted user U2 and
distance (d2) for several BS transmits Signal to Noise Ratio
at 120588 = minus20minus1020 119889119861is depicted in with a=005 and 01 and
d1=200m is depicted in the figure The results stated that the
U1(SOP) is a gradually reducing function as per d2 that
implies that the increasing value of d2 leads to the
improvement of the SOP of U1 Since the provided constant
threshold ϵ in SOP restraint U2must be situated at a larger
space when compared with threshold value to obtain the SOP
of U1 Apart from that it is normal that the high the target
secrecy rate rises the SOP of U1
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Figure 4 The Secrecy outage probability
Feasible Pairing in th SOP of pair OP and U1 with the
enhanced power allocation factor (a) in which d2 = 700 m d1
= 200 m 120588 = 15 dB and ϵ = 01 The results depicted that the
the pair OP and SOP of user U1 with increased a for two (d2)
various distances of the (U2) untrusted user The results
approve the convex nature of the pair OP and the SOP curve
is gradually decreasing on the basis of a Generally during the
increase in a the power assigned to the weak user message
decreases that minimize the ability of U2 for discriminating the
superior positioned signals thereby improving the SOP of U1
Figure 5 The Pair outage probability
Pair OP in case of rising U2 untrusted user in distance (d2)
for different base station transfer the signal to noise ratio(120588 =
5 15 25 dB) where a = 015 and d1 = 200 m
Figure 6The infeasible pairing of secrecy outage
probability of the pair OP and U1
The infeasible pairing of SOP (U1) and the pair outage
probability with the enhanced allocation of the power ad1(200
m)d2(300 m)120588 = 15dB and ϵ = 0
The figure 6 depicted that the
The figure 6 shows the similar plotting of the data by altering
the untrusted user location by transferring it to a BS closer
distance (d2 = 300 m) It also depicted that the U1 SOP
constraint of is disrupted at a because the SOP is more than ϵ
The accuracy is well-matched and verified with all range of
numerical simulation The results noticed that the efficiency is
based on the comparative locations of the two user with the
base station
Figure 7 The figure 7 depicts that SNR versus strictly
positive secrecy rate
The observed graph proves that the secrecy capacity
outperforms the existing techniques The proposed precoding
application increases the performance of the system The
transmission power of the system is the power required to
transmit a particular data When there is an increase in the
number of users there is the possibility of inference in the data
transmission and hence the efficiency of the data rate may be
affected Depending on these instances the efficiency of the
antenna capacity to withheld and accommodate the data
determined
Figure 8 The power radiated by BS antenna
In the figure 8with respect to the simulation setup the
precoding methods are performed based on the radiated
power per BS antenna is depicted The results observed the
better efficiency of the proposed system The proposed proves
to be better when compared with existing linear precoding
methods in the prescribed three metrics thereby stating that
MRT may be utilized for the the examination of the secrecy
capacity Our proposed technique spends less radiatated
power thereby increasing the overall capacity of the system
5 CONCLUSION The NOMA system decodes the messages of other user pairs
on the similar resources thereby promoting user possibility
The technique interprests a security threat in which the BS
serves the untrusted users The study analysed the SOP and
OP in both multi user and two user NOMA system in which the
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2533
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base station pairs the trusted user in closed type of
expressions The proposed (Interference mitigation using
POMDP) also enable the understanding of possibility of
achieving outage optimal efficiency to pair under SOP
constraints The numerical verifications verified the efficiency
of the analytical derivations
6 REFERENCES [1] ALI M S TABASSUM H amp HOSSAIN E 2016
Dynamic user clustering and power allocation for
uplink and downlink non-orthogonal multiple access
(NOMA) systems IEEE access 4 6325-6343
[2] ARAFA A SHIN W VAEZI M amp POOR H V
2019a Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
15 210-222
[3] ARAFA A SHIN W VAEZI M amp POOR H V
2019b Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
[4] CAO K WANG B DING H LI T amp GONG F
2019 Optimal Relay Selection for Secure NOMA
Systems under Untrusted Users IEEE Transactions
on Vehicular Technology
[5] DANG S CHEN G amp COON J P 2018
Multicarrier relay selection for full-duplex relay-
assisted OFDM D2D systems IEEE Transactions on
Vehicular Technology 67 7204-7218
[6] DANG S COON J P amp CHEN G 2017 Outage
performance of two-hop OFDM systems with
spatially random decode-and-forward relays IEEE
Access 5 27514-27524
[7] FIANU S amp DAVIS L B 2018 A Markov decision
process model for equitable distribution of supplies
under uncertainty European Journal of Operational
Research 264 1101-1115
[8] FURQAN H M HAMAMREH J amp ARSLAN H
2019 Physical Layer Security for NOMA
Requirements Merits Challenges and
Recommendations arXiv preprint arXiv190505064
[9] HOU L ZHENG K CHATZIMISIOS P amp FENG Y
2018 A Continuous-Time Markov decision process-
based resource allocation scheme in vehicular cloud
for mobile video services Computer
Communications 118 140-147
[10] KOKSHOORN M CHEN H WANG P LI Y amp
VUCETIC B 2016 Millimeter wave MIMO channel
estimation using overlapped beam patterns and rate
adaptation IEEE Transactions on Signal Processing
65 601-616
[11] LIU Y ELKASHLAN M DING Z amp
KARAGIANNIDIS G K 2016 Fairness of user
clustering in MIMO non-orthogonal multiple access
systems IEEE Communications Letters 20 1465-
1468
[12] LV L CHEN J NI Q amp DING Z 2017 Design of
cooperative non-orthogonal multicast cognitive
multiple access for 5G systems User scheduling and
performance analysis IEEE Transactions on
Communications 65 2641-2656
[13] SUN Y NG D W K ZHU J amp SCHOBER R
2018 Robust and secure resource allocation for full-
duplex MISO multicarrier NOMA systems IEEE
Transactions on Communications 66 4119-4137
[14] ZHANG H YANG N LONG K PAN M
KARAGIANNIDIS G K amp LEUNG V C 2018
Secure communications in NOMA system
Subcarrier assignment and power allocation IEEE
Journal on Selected Areas in Communications 36
1441-1452
[15] ZHAO T LI G ZHANG G amp ZHANG C-X
Security-Enhanced User Pairing for MISO-NOMA
Downlink Transmission 2018 IEEE Global
Communications Conference (GLOBECOM) 2018
IEEE 1-6
i
ABSTRACT
The landscape of future fifth-generation (5G) radio access networks is
expected to seamlessly and ubiquitously connect everything and
support higher traffic volumes densely connected wireless devices and
diversified requirements on reliability latency battery lifetime etc as
opposed to the current fourth-generation (4G) cellular networks
Moreover in unexpected or emergencies (such as disaster relief and
service recovery) the deployment of terrestrial infrastructures is
economically infeasible and challenging due to high operational
expenditure as well as sophisticated and volatile environments To
address such novel issues intelligent heterogeneous architecture by
leveraging unmanned aerial vehicles (UAVs) (or commonly known as
drones) has been considered to be a promising new paradigm To
improve the system performance of UAV communication in 5G
networks physical layer techniques are of much concern as they affect
the applications of UAVs significantly In this research work security
aspects of NOMA-based UAV communication network have been
considered for optimization as physical layer security in a wireless
communication network is not as robust as wired communication due to
fading and varying SNR scenarios Here primarily two usersrsquo models
as the trusted and untrusted user communicating with BS have been
optimized for outage-optimal performance considering pair Outage
probability and Secrecy outage probability as performance metrics The
achieved results are extended to multi-user scenarios also and for the
optimal policymaking dynamic programming and Partially Observable
Markov Decision Process (POMDP) optimization approaches have
ii
been simulated and verified The simulated results have shown that
POMDP has potential consideration as a resource scheduling
optimization technique in the NOMA-UAV communication network for
providing secure and more robust performance
iii
Acknowledgment
Completing a PhD is a tough task that requires hard work and a lot of effort This is
often an overwhelming but also great experience that I would not have been able to
complete without the assistance and support of so many people Thus it is my great
pleasure to thank all those people First of all I would like to thank almighty for giving
me the strength to carry out this task I would like to deeply thank Dr Chetan B Bhatt
my supervisor for his guidance encouragement and support over these years This
research work would not have been possible without his constructive pieces of advice his
systematic guidance and his patient support thought out the duration of my research work
I would like to express my sincere gratitude to Dr Harshal A ALOORKAR and Dr
KIRAN R TRIVEDI Dr Mehul Raval my doctoral progress committee members Their
rigorous style of reviewing and constructive feedback with valuable suggestions of Dr
Prakash Gajjar Mr Hitesh Panchal and Mrs Monali Mandli who spent their valuable
time whenever required for discussing aspects of this work and provided relevant material
as well Mr Parth Modi and Mr Jagadish Patankar to initiate and inspired me a lot to
continue my work Mr Mukesh Sharma who help in maintain documents I am also
thankful to my parents and family members who always stood with me in each critical
situation and supported me endlessly I am thankful to all EC departments of various
polytechnic and degree engineer colleges for their cooperation in every possible means
Lastly I would thank all the people who directly or indirectly helped me during this very
important phase of my life
Pankaj Manubhai Patel
vi
List of Abbreviation
3GPP 3rd Generation Partnership Project
5G Fifth Generation
A2G Air to Ground
AWGN Additive White Gaussian Noise
BDM Bit Division Multiplexing
BS Base Station
BPCU Bits Per Channel Use
CDMA Code Division Multiple Access
CR Cognitive Radio
CSI Channel State Information
CNPC Control and Non-Payload Communications
CRN Cognitive Radio Networks
D2D Device-to-Device
DCP Difference of Concave Programing
DOMP Dynamic Optimization Method of Programming
FR Floating Relay
GSM Global System for Mobile Communications
HLPSL High-Level Protocol Specification Language
ICT Information and Communication Technology
IoT Internet of Things
IRS Intelligent Reflecting Surface
IMT Information Management Technology
vi
LDS Low-Density Spreading
LTE Long Term Evolution
LTE-A Long Term Evolution Advance
MCR Multicast Cognitive Radio
MI Mobile Internet
MIMO Massive Multiple-Input Multiple-Output
mm-Wave millimeter Wave
MTC Machine-Type Communication
MUSA Multi-User Mutual Access
NOMA Non-Orthogonal Multiple Access
OFDMA Orthogonal Frequency Division Multiple Access
OMA Orthogonal Multiple Access
OP Outage Probability
POMDP Partially Observable Markov Decision Process
PLS Physical Layer Security
PDMA Pattern Division Multiplexing Control
PUN Primary User Networks
QoS Quality of Service
RIS Reconfigurable Intelligent Surface
RNRF Random Near-Random Far
Rs Target Secrecy Rate
SAGIN Space-Air-Ground Integrated Networks
SIC Successive Interference Cancellation
STBC Space-Time Block Coding
vi
SBF Secrecy Beam Forming
SCMA Sparse Code Multiple Access
SOP Secrecy Outage Probability
TAS Transmit Antenna Selection
TDMA Time Division Multiple Access
UAVC Unmanned Aerial Vehicle Communication
UMTS Universal Mobile Telecommunication Systems
URLLC Ultra-Reliable Low Latency Communication
vii
List of Figures
Figure Title Page
No
11 Usage of wireless sensor network and UAV in the
hazardous disaster control
6
12 UAV network applications types with security services
architecture
8
13 UAV-assisted heterogeneous network architecture 12
14 Security problems in the UAV 15
15 Comparative analysis of NOMA vrsquos OMA 18
21 Vehicular communication NOMA system 28
22 RS-NOMA against an external eavesdropper 31
31 Downlink NOMA network 44
32 Uplink NOMA network 46
33 Multi-two user architecture of NOMA system 49
34 Flow Diagram of the proposed system 50
35 Near and Far User 51
41 Impact on Sop with increase distance between BS and user U2 60
42 Impact on Sop with increase distance between BS and user U2 61
43 Feasible pairing t Vs pair OP 61
44 Infeasible pairing t Vs pair OP 62
45 Secrecy outage probability 63
46 Pair outage probability 63
47 SNR versus Strictly positive secrecy rate 64
48 Power radiated by per MMBs antenna 64
viii
List of Tables
Table Title Page
No
11 Physical layer hazards and measures in UAV wireless
communication network
13
21 Comparative analysis 33
31 List of parameters59 54
41 Simulation parameters 59
ix
Table of Content
Sr
No
Title Page
No
I Abstract I
II Acknowledgment II
III List of Abbreviation III
IV List of Figures Iv
V List of tables V
1 Introduction 1
11 Modern technology and its needs 1
111 Long term evolution of 4G network 2
112 Migration from 4G LTE to 5G for UAV communication 3
12 UAV assisted communication in heterogenous sensor network 5
121 Introduction to UAV Communication network 7
122 Tyews of UAVs 8
1221 UAVs as flying BSs 8
1222 UAVs as aerial UBs 10
13 Unmanned aerial vehicle for 5G network 11
14 Physical layer insecurity in UAV communication network 12
141 Principles of security 13
15 Non-Orthogonal Multiple Access (NOMA) system secured
communication
16
151 Comparison of NOMA Vs OMA 16
1511 Spectral throughput and efficiency 17
1512 User fairness and higher lately 17
1513 Compatibility 17
16 Problem identification 18
17 Motivation 19
18 Aim and objective of the research 20
19 Thesis organization 21
2 Literature review 23
x
21 Integration of UAV Networks for 5G and B5G communication 23
22 UAV-NOMA in physical layer security enhancement 26
23 Research methodology 38
24 Summary 39
3 System model for NOMA-UAV communication 41
31 NOMA -UAV system secured communication for 5G 41
311 The basic scheme of NOMA 41
312 Downlink of NOMA 44
313 Uplink of NOMA 46
314 Comparison of NOMA and OMA 47
32 PLS performance metrics in NOMA -UAV communication 47
321 SOP and OP - two user and multi-user NOMA system 48
322 System Model 48
323 Partially Observable Markov Decision Process-POMDP 50
324 Problem formulation 52
33 Performance Analysis Improving PLS Insecurity of NOMA
System
53
331 The pair OP calculation 53
332 Pseudo-code for the proposed algorithm 55
34 Summary 57
4 Result and discussion 58
41 Performance measure of secured NOMA-UAV communication
model
58
42 Numerical result and discussion 59
421 Feasible amp Infeasible pairing of trusted amp untrusted
users
60
422 The secrecy outage probability and pair outage
probability
62
423 SNR versus strictly positive secrecy rate 63
424 Power radiated by per MMBs antenna
64
43 Conclusion and scope of future work 65
431 Conclusion 65
432 Future scope 66
xi
5 References 67
8
Publications 78
1
CHAPTER -1
INTRODUCTION
11 Modern technology and its needs
Mobile technology has undergone various generational shifts transforming the
cellular framework into a worldwide set of interconnected networks In recent days
the fifth generation (5G) has delivered voice as well as video streaming It has a
very complex range of networking services for more than nine billion users and also
billions of devices that will be connected (Hu 2016) However 5G offers a new
outlet for reflection It involves a radial network architecture for the installation of
communication-type machines 5G network can also include powerful support
applications with widely varying operating parameters 5G is a blend of network
technologies that have been developed The new 5G technology will be able to
exchange information anywhere every time for the benefit of people enterprise
and society and technical environments using a restricted access bandwidth to
carry data Now it is more than a modern series of technologies and as opposed to
previous generations would entail tremendous infrastructure or machinery
upgrades This technology aims to expand on the advances that telecommunications
systems have already achieved The projected standards of efficiency that
technologies would need to resolve are
bull Five times reduce end-end latency
bull Ten to a hundred times the higher complex rate of user data
bull Battery life is ten times longer
bull 10 to 100 times higher number of connected devices
In this research work the UAV-assisted communication over the 5G network has
been proposed with enhanced physical layer security aspects NOMA has been
proposed as the reference framework architecture for UAV communication as one
of the recent popular 5G techniques Along with the advantage of suitability in UAV
communication network NOMA has the disadvantage of insecurity in the physical
layer Here the migration of Long Term Evolution (LTE) to advanced physical layer
2
security for Unmanned Aerial Vehicle communication (UAV) over 5G network has
been proposed and also improve the insecurity of Non-Orthogonal Multiple Access
(NOMA) System We will discuss in the further chapter the proposed work This
chapter describes the introduction and basic concepts of the 5G networks with
methodology techniques and types It states the problem identification motivation
and further aim and objective of this work
111 Long Term Evolution of 4G Network
LTE is customary for 4G wireless broadband trends that provide improved network
capability and gives mobile device users speed It offers high peak data transform
rates in the range of 100 Mbps and 30 Mbps downstream and upstream
respectively It provides a capacity of scalable bandwidth mitigated latency and
backward compatibility with the previous Global System for Mobile
Communications (GSM) and Universal Mobile Telecommunication Systems
(UMTS) technology
The fourth development of cellular networks (4G) has already been developed to
meet the standards of the 3G and 2G families Every 10th year a new mobile
generation claimed to be familiarized with the first 1G system in 1981 tracked by
the 2G system that went on to roll out in 1992 and 3G launched in 2001 growth in
the year 2002 of 4G networks The actual new revolution began in December 1998
with the 3rd Generation Partnership Project (3GPP) With high-quality video and
images 3G networks are designed for multimedia networking with them Peoples
communication can also be enhanced and connectivity to public and private
network information and resources has improved with higher frequencies and new
flexible communication features third-party device applications
With the start of LTE-Advanced several vital demands and improvements are
beginning to emerge Various importance purposed for LTE-Advanced can be
exemplified as follows (Abed)
bull Provides spectrum output with LTE delivered more than three times
bull Spectrum can help scalable bandwidth and convergence of the spectrum
where it is necessary to use a non-contiguous range
3
bull Provides uplink and downlink spectrum output that varies between
15bpsHz and 30bpsHz
bull The edge throughput must be twice that of the user cell in LTE
bull From idle status to connected status the communication latency scenario is
smaller than 50msec and less than 5msec for direct packet transfer
bull Any users total throughput must be three times that of LTE
bull LTE advancement will provide 3GPP as well as LTE compatibility via inter
networking
bull The mobility conditions that are used in LTE are identical
The latest LTE advanced requirements are not yet included in device
specifications there are high-level purposes Before it is fixed in the specifications
and needs to be tested much effort remains to be approved
112 Migration from 4G LTE to 5G for UAV communication
The productive implementation of a UAV communication network in 4G and the
upcoming wireless network is included in identifying combined solutions to test
the correlation with both multitudes and also energy-efficient transmission Then
the process of the UAV-BS to optimize coverage and power It is stated that the
energy efficiency of the UAV-aided communication system is needed Efficient
energy utilization contributes to increased air time in the contact system and
increased joulesbits at a provided energy level Also aerial cell coverage and
ability may be because of various parameters such as antenna gains transmission
strength radio access technology UAV altitude and deployment environment
4G is the fourth generation of network infrastructure technologies to replace 3G and
in addition to the popular 3G4G methods Code Division Multiple Access
(CDMA) Time Division Multiple Access (TDMA) and Orthogonal Frequency
Division Multiple Access (OFDMA) Researchers are designing the latest Non-
Orthogonal Multiple Access (NOMA) technologies to be used because of their
capability to improve the performance of communication networks Non-
4
orthogonality-based device designs have recently been developed for use in
communication networks and drawn considerable interest from researchers
Henceforth Multiple Access (MA) methods can be sub-divided as OMA and
NOMA Each user may utilize orthogonal communication resources to determine
multiple access interference inside a frequency band code and time slot in OMA
Its methods such as First generation (1G)- FDMA 2G -TDMA 3G -CDMA and
4G - OFDMA have been used in previous network generations In NOMA by
producing a higher spectral efficiency however enabling some amount of multiple
entree intrusion in receivers and multiple users may use non-orthogonal resources
simultaneously Recently the credibility of NOMA as a solution to the problems of
the next generation of wireless networks has been increased Compared with OMA
technologies NOMA has been described to improve spectral quality be well-
adjusted with air connectivity and can provide accommodations for multiple
strategies at the same time of frequency Therefore enabling excellent progress to
massively correlated devices
In particular NOMA also affects mitigating interference by using OFDMA as an
orthogonal method or through offering a standard intra-cluster access beam across
multiple users and inter-cluster access in NOMA Recent studies have concentrated
primarily on the provision of Air to Ground (A2G) connectivity services through
optimization of a different point of view
The output of the UAV-based communication network was discussed in the Device
to Device (D2D) implementation setup The proposed system hypothesized
interference caused through D2D network nodes deprived of acknowledging the
occurrence of global BS Also several studies addressed the efficiency of NOMA
It permitted the deployment of fixed-wing to assist coverage in-ground user located
outer location of offloaded BS
NOMA systems are divided into two categories namely code domain and power
domain multiplexing In the power domain user accounts are allocated to different
power coefficients as per their channel complaint to reach optimal device
efficiency Multiple user signals are applied to the side of the sender Then on the
received signal Successive Interference Cancellation (SIC) is implemented to
decipher signals in sequential order until the predicted signal is achieved offering
5
a good trade-off between efficiency of the system and user fairness Different code
domain multiplexing is Sparse Code Multiple Access (SCMA) Low-Density
Spreading (LDS) and Multi-User Mutual Access (MUSA) Compared to power and
code domain multiplexing there are alternate NOMA techniques such as Bit
Division Multiplexing (BDM) and Pattern Division Multiplexing Control (PDMA)
However this multiplexing is capable of improving the efficacy of spectral It
requires a large transfer of bandwidth which is not appropriate for new methods
But on the other side the power domain has direct execution since there is no need
for significant improvements to the current networks It also does not necessitate
bandwidth to increase spectral efficiency In this chapter the main emphasis
depends on the power domain NOMA While OMA strategies can produce the best
results also with necessary receivers due to no mutual intervention among users in
an optimal situation they cannot even resolve increasing problems due to growing
demands on connectivity growth and even beyond
12 UAV assisted communication in heterogeneous sensor network
Wireless communications had created a golden chance for urban and rural
territories The LTE (Long term evolution) and LTE-A (Long term evolution
Advance) had offered the service (with QoS) for all customers through wireless
The traffic properties in the machine type communications (MTC) and the
accumulation of the MI (Mobile Internet) had made the difficulty of implementing
the cellular communication networks Installing base stations was impractical in the
urban areas due to its cost To overcome this issue the UAV suggested that it
contains the merits of compatibility and high battery life and is affordable Most of
the devices like the sensor nodes and professional cameras had been used in UAV-
assisted networks Here the UAV-assisted floating relay (FR) was launched in the
cellular communication networks UAVs were implemented more with WSN
(wireless sensor networks) The base stations were adopted with the UAV So the
MI and MTC traffic challenges were controlled (Yue Li amp Cai 2017)
UAV-assisted Heterogeneous networks had implemented in vast practical
applications UAV helped heterogeneous networks were applied in the military
department In the military the UAV had examined and surveyed the opposing
6
countryrsquos activities for security The UAV-based heterogeneous networks were
used in the military sectors where a novel authentication scheme was introduced
As The one-to-one communication via WSN was considered as secured
communication WSN had the disadvantage of consuming power The
authentication was implemented in the tool of Automated Validation
of Internet Security Protocols and Applications (AVISPA) in which the expression
had been written in the High-Level Protocol Specification Language (HLPSL)
programming language The authentication had evaluated between the user and the
base station Similarly the authentication between the user and the UAV was
calibrated The citizen and economic safety are predicted and conserved through
reliable communication in the military by obtaining foes exploration information
The faithful secured communication was confirmed using AVISPA (Rashid et al
2019)
Figure 11 Usage of wireless sensor network and UAV in the hazardous
disaster control
The integration of the wireless sensor networks and the unmanned aerial vehicle
UAV was analyzed and applied to manage the natural disaster illustrated in Figure
11 The aircraft can prevent the fire spreading drop sensors the temperature map
and biodiversity map by sensors the wildfire can easily route The wild animals can
7
be tracked and the dynamic data of moving animals can be gathered by WSNs The
biologists can fix the sensor in the animals collar the radiation that positively
affects humans can be observed in affected areas The WSNs help to prevent heart
attack of a person by monitoring heart rate The state of health can be known
through a message alarm using a GPRS system
The cooperative networks of WSN and UAV were implemented in the military
sector for the advantageous feature The UAV was providing good connections
overlapping and overall data rate The conventional UAV method aided sensor
networks concentrated only on the single tasks of monitoring accumulating
information and localization The multi-UAV had not been implemented in the
sensor networks The animal colony perception technique was utilized for
scheduling the resourced and the target assignment Functions of multi-data were
used for localization by the target recognition method (Gu Su et al 2018)
The Physical Layer Security (PLS) was achieved through 5G technologies delicate
coding for the PLS dense MIMO multi-input multi-output mm-Wave frequency
band using heterogeneous sensor networks NOMA and full-duplex mode of
communication IoT and Machine-type communications (MTC) emerged in the 5G
systems (Wu et al 2018)
121 Introduction to UAV communication network
The usage of the UAV will develop more in the next era These pre-programmed
aircraft are intended for applications in several civil settings as well as industrial
visualization agriculture rescue and search and then receiving of scientific data
These devices are called the unsuccessful inaccuracy of drones which must be
incorporated into the system of national airspace as well as worldwide The usage
of UAVs in the neutral form is always secure It has a direct inference for the control
and a payload communication system that is utilized to function effectively
Similarly surveillance and navigation operations must be made more accurate and
consistent Due to these critical factors many kinds of research in a UAV testing
development and standardization difficulties are undergone through industries
education and governments
8
Even though civil aircraft had been operating for many years yet UAV offers new
consequences in terms of various flight profiles For example high dynamic
maneuvers and low elevation flights need bandwidth video and different ground
site characteristics namely clutter locations and elevation antennas which are low
This chapter explains the core topic of the proposed work The migration of LTE
4G towards the advanced one of the physical layers for UAV communication It has
higher mobility and lower expense identified in a broad range of applications
122 Types of UAVs
The UAVs have a two-network application with security services such as UAVs as
Flying Base Stations (BSs) and UAVs as Aerial BSs in the presence of
eavesdroppers
(a) UAVs as Flying BSs (b) UAVs as Aerial mobile UEs
Figure 12 UAV network applications types with security services
architecture
1221 UAVs as flying BSs
The required infrastructure can be destroyed in natural disasters particularly
tsunamis earthquakes and snowstorms and the requisite emergency data traffic
cause both overloading and congestion of neighboring mm-Wave (Zeng et al
2016) A capable explanation is to rapidly introduce low-altitude UAVs as flying
9
BSs in such a network breakdown to improve the communication infrastructure to
mitigate cell congestion or site failure thus creating a small aerial cell
In this situation wireless communications can occur in an ad-hoc manner with
UAVs to UEs UAVs to UAVs As highlighted in Figure-12 (a) and control
stations of UAVs to ground It will increase capability dramatically and enlarge the
target of wireless networks in provisional measures as it is possible to create LoS
communication links among UAVs and UEs supported on the ground Yet form an
operating aerial cell system to monitor ground segments of UEs mobility which is
more stable to minimize sporadic connectivity on the other side
Also this can be expanded to allow several UAVs-BSs to be deployed to increase
the exposure area for supporting a wide range of UEs A network period various
UAVs-BSs is entirely independent A new paradigm was introduced through
collaboration between UAVs-BSs to extend the feasibility for a single UAV from
either a stand-alone active sensor to a wireless network over the next generation
There is a growing concern about the privacy problem in tandem with the brief
introduction of this network Wireless protection is the central issue of the
communication level wherever eavesdropping subsidizes for deliberately listening
to a source of secret information which harms the extensive placement of UAV-
BSs
A UAV-BSs is to mount several antennas in the UAV-BSs the benefits of multi-
antenna innovations geographical degree of freedom that offers an ability for UAV-
BSs to transmit eavesdropping airborne beams
Notice that in UAV systems multi-antenna technology can be technically applied
while directly modifying the separation of the antennas The existing system has
shown that transmitted beam forming models can significantly boost the
confidentiality efficiency of wiretap channels for multiple antenna transmitters
Noise may be inserted with the signal to substantially degrade the acknowledged
SINR at the eavesdroppers to prevent the information overflow
10
1222 UAVs as aerial UEs
This has already been demonstrated by reaping the benefits of Wi-Fi and LTE
technologies through field trials (Van der Bergh et al 2016) UAV-UEs typically
get their tasks for a variety of convincing IoT applications mainly in air freight
services like the google wing project Unlike conventional land base package
delivery but UAV delivery has distinctive merits such as
bull Acceleration of land transport as UAVs are not liable to road jams
bull Connection to areas that are difficult to reach
bull Decreasing the use of capital about workforce and electricity
UAV distribution is significantly dependent on having reliable and secure wireless
communication among UAVs and ground BSs especially if the UAV needs control
outside LoS the UAV-UEs are used which can develop LoS connectivity to cellular
BSs The UAV-UEs on the one hand provides high-speed access to data as it can
fly continuously in either direction On the other hand the installation of UAV-UEs
can lead to significant interference with the ground BSs in the execution of their
missions
A wide-scale installation of UAV-UEs is only feasible for this reason if the issues
of interference management are tackled It is widely known that interference
negatively affects wireless networks As highlighted in Figure-12 (b) indeed aerial
and ground UEs are served through a cellular network with a possible eavesdropper
that tries to intercept the message intended for permissible basic UEs
A cost-effective approach is to be used for coordination among ground BS and
UAVs to enhance secure transmission which is part of the UAVs acting as friendly
transmitters to degrade the wiretapping channels efficiency and thus enhance
secrecy efficiency A UAV acting as a mobile jammer can dramatically and
dynamically change its position as near as possible to the earth eavesdropper and
distribute them by sending the radio signals whereas strong LOS connection
characteristics are a beneficial feature with less earthly fading and shadowing
impairment
11
13 Unmanned Aerial Vehicle for 5G Networks
UAVs have technologically advanced as a revolutionary movement in delivering
pervasive connectivity from either the platforms of the sky as aerial
communication particularly for temporary User Equipment (UEs) (B Li et al
2019) Due to fully controllable UAV flexibility through miniaturization as well as
continuous cost reduction low-altitude UAVs are rapid and flexible designed for
operation and reconfiguration They are probable to have higher Line-of-Sight
(LoS) ties to ground UEs
A broad range of applications like inspection of infrastructure precision farming
and disaster area monitoring is becoming accessible in this aspect Moreover
further projects have also been set up to employ aerial platforms for broadband
access to distant elements such as the Google Loon and the Facebook Drone Project
to mention Highly populated UEs are desperate for broadband wireless
communications with the coming 5G period and network providers are supposed
to maintain numerous networks with high demands for wireless data like
multimedia streaming and also video downloads The relentless growth in the
amount of traffic of mobile networks puts a burden on operators in the form of
higher capital and operational expenditure Deploying small cell networks is an
intuitive alternative to outsource cellular traffic
Although in unforeseen or temporary events as mobile environments are
complicated volatile and heterogeneous the implementation of terrestrial
infrastructures is difficult The accessibility of aerial access points to enable
extensive complex connections is one possible solution However in unforeseen or
temporary events as mobile environments are complicated volatile and
heterogeneous the implementation of terrestrial infrastructures is difficult The
accessibility of aerial access points to enable extensive complex connections is one
possible solution UAV communication performance benefits from the simplicity
of the compact transceiver and progressive control methods that obtain broad
exposure and set up internet networks
12
Figure 13 UAV-assisted heterogeneous network architecture
The above Figure 13 is depicted to build flexibility of the network with enhanced
ability and elasticity It is a good network that offers security endowment This is
due to the transmitting information to UAV communication which is tapped
through ground unauthorized user and is known as an eavesdropper
Here through eavesdropper based on the upper layer cryptographic techniques
wireless communication in contradiction of unauthorized access has been protected
However it is very tough to achieve because of key management as well as more
computational difficulties in developing network architecture PLS affects the
characteristics of intrinsic wireless networks as a fascinating preparation such as
interference noise fading loss collecting signal characteristics in malicious
eavesdroppers and techniques of signal processing
14 Physical Layer Insecurity in UAV communication network
Jamming is either a well-defined WSN attack on a physical layer It disrupts the
radio waves being used by nodes of the network The attacker successively
expresses the denial of the simple MAC protocol over the wireless network The
impressive network can be disrupted at which a single frequency is being used
13
throughout a network (Modares et al 2011) In addition jamming can increase
energy consumption in the node by inserting impudent packets The receiver nodes
will also generate resources when receiving the packets In (Jeon 2006) four
different terms of jamming attacks that an intruder could use to interrupt the
wireless network activity Tampering is yet another physical layer assault
Table 11 Physical layer hazards and measures in UAV wireless
communication network
(Kumar et al 2014)
Hazard Security measures
Jamming Channel blacklisting and hopping
Interference Channel hopping and blacklisting
Tampering Security and key modification
Sybil Physical security of the system
Table 11 describes physical layer hazards and their security measures in WSN
which tampering and jamming are considered as the main attack in the physical
layer in WSN
141 Principles of security
The security requirement of UAV communication network is as follows (Kumar et
al 2014)
Confidentiality Ensure that only the approved sensor nodes could get the contents
of the texts
bull Authentication Ensure that the data is introduced from the sound source
bull Integrity Ensure that every received text has not been modified to be sent
by unauthorized users
14
bull Freshness Make confirm that no old information has been reiterated
bull Availability services are feasible at any time through WSN or by a single
node
The standard attacks of the physical layer are as follows (Sastry et al
2013)
bull Jamming The transmission of the radio signal can interfere only with radio
frequencies used through WSN which is known as jamming As the
capacity grows it may influence more significant portions of the network
by transmitting other radio signals The opponent will use a few nodes to
occupy the entire channel This state is called physical layer jamming which
results in a denial of service In this scenario the opponent will not be
permitted to have any knowledge but will be capable of preventing
communication to any nodes
bull Tampering Often the nodes tampered through an opponent This mode is
called tempering Here the attackers can destroy exchange and
electronically confront nodes to obtain information from counter measures
towards jamming that have been planned as spread as well as frequency
hopping
bull A security mechanism is used in WSN to track avoid and recover from
security attacks A wide range of security schemes can be devised to counter
malicious threats which can be classified as high and low levels
bull Secrecy and Authentication Most network sensor applications need
protection from eavesdropping packet alteration and injection Early
networks are used for connection layer cryptography as this approach offers
the easiest deployment of network cryptographic solutions
bull Privacy Like all other conventional networks the radio networks have also
brought secret issues to allow Initially sensor networks are implemented
for legitimate purposes and can eventually be used unexpectedly
Knowledge of active sensor nodes as well as the acquisition of data is
exceptionally crucial
15
bull Critical launch and trust setup The primary prerequisite for setting up a
network is the development of keys (cryptography) Sensor devices
typically have minimal computing capacity and public cryptographic
primitives are too difficult to adopt Critical establishment and strategies
need to be scaled to network with thousands of nodes
bull Secure routing Routing as well as data forwarding is a problem that
confronts to facilitate communication in networks Regrettably the latest
protocols encounter a variety of security flaws
bull Robustness of communication Does An opponent challenges to interrupt
the operation of the network
Figure 14 Security problems in the UAV
Figure 14 illustrated the security difficulties in a UAV The physical layer security
in the UAV wireless networks was examined The UAV had affected by both active
eavesdropper and passive eavesdropper This paper proposed the trajectory design
and cooperative UAV for constraining the eavesdropper NOMA MIMO mm-
Wave frequency band in UAV would cause better spectral efficiency and security
(Xiaofang Sun et al 2019)
UAV implementation of the 5G communication was considered advantageous The
UAV was assumed as the novel wireless network technique for the territory users
and their base stations The UAV had resulted in high altitude So the UAV had
16
considered a superior line of sight At the same time the possibility of security
problems was raised in a UAV The secrecy in the existence of eavesdropper the
jammer in the ground was performed using the UAV UAV aided territory security
was proposed The UAV was involved in inspecting the eavesdropper and hazard
jammers on the base stations territory UAV had targeted the global position system
spoofing for assisting the authentic users and performed the role of an artificial
eavesdropper for excluding the eavesdropper and jammers in the ground (H-M
Wang et al 2019)
15 Non-Orthogonal Multiple Access (NOMA) System Secured
Communication
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
151 Comparison of NOMA Vs OMA
Comparison of the NOMA and OMA can be discussed as follows
17
1511 Spectral throughput and efficiency
In OMA a resource is allotted to the distinct user whether it is good or bad in a
channel scenario like OFDMA Thus the whole process moves from less
throughput and performance
While the same frequency is allotted to the multiple-use at the same time with good
or bad channel operation in NOMA here the weak user gets the allocated for the
resources which the strong user can also use it And the interference can be reduced
by the SIC process on the receptor side of the user Consequently the probability
with the increased spectral efficiency as well the high throughput will be
maximized
1512 User fairness and higher lately
A user of fair channel complaints has higher precedence to be served in OMA In
contrast a user with a poor channel complaint is to remain activity which causes
the issue of user fairness and higher latency Yet OMA cannot assist colossal
connectivity Whereas NOMA helps multiple users with various channel
procedures and offers increased fairness massive connectivity and lower latency
1513 Compatibility
NOMA has compatibility with the current and upcoming scenario meanwhile no
need for necessary changes to the previous methods As an instance NOMA has
been bought up in the 3G Partnership Project LTE Advanced (3GPP LTE) Though
NOMA contains many characteristics that can assist the upcoming generations and
it has some restrictions that can be explored with its full benefits Those restrictions
are as follows
bull Each user has to decrypt the signals of other users until decrypted their
signal the complexity of the receiver would be strengthened in NOMA as
opposed to OMA which creates a long pause
bull Also data on channel quality for all users should be returned to the BS but
this results in substantial CSI input overhead Furthermore if any issues
arise to any consumer during the SIC process the likelihood of consecutive
decrypting errors will be improved
18
Figure 15 Comparative analysis of NOMA vrsquos OMA
As an outcome the number of users is reduced to ignore the spread of such
debugging Another aim of restricting the number of users is that there must be
substantial variations in channel revenues between users with different channel
grievances to provide network reliability
16 Problem Identification
The NOMA-based architectures main feature is to configure trusted and untrusted
users when more than one eavesdropper is present in the dense setting of todayrsquos
and future sophisticated wireless communication networks This research aims to
examine the security efficiency suggested for mission-critical applications in the
NOMA-based UAV communication network The proposed system underpins two
user NOMA frameworks The possibility of paring both users was explored with
PHY performance measures in mind Outage probability (OP) and Secrecy Outage
Probability (SOP) Dynamic Optimization Method Programming (DP) and Partially
Observable Markov Decision Process (POMDP) optimization have also been
analyzed to explore the feasibility of achieving an outage-optimal output for the
pair under the heavy users secrecy outage restriction The optimized theoretical
findings are applied to the multiuser scenario The identifications were tested
through a computer model in which POMDP has shown substantial progress over
the dynamic optimization method to program
19
17 Motivation
Unmanned aerial vehicle (UAV) wireless communications have experienced an
upsurge of interest in both military and civilian applications due to its high
mobility low cost on-demand deployment and inherent line-of-sight air-to-ground
channels However these benefits also make UAV wireless communication
systems vulnerable to malicious eavesdropping attacks
Despite the promising gains brought by UAVs the open nature of air-to-ground
wireless channels makes secure information transfer a challenging issue
specifically on the one hand information signals transmitted over wireless LoS
channels are likely to be intercepted by some undesired receivers which lead to a
risk of information leakage On the other hand wireless UAV transceivers are
vulnerable to malicious jamming attacks Hence security plays an extremely
important role in UAV wireless communications Unfortunately traditional
encryption techniques require high computational complexity leading to a large
amount of energy consumption which may not be suitable for UAV systems As an
alternative physical layer security is computationally efficient and effective in
safeguarding wireless communication networks via exploiting the inherent
randomness of wireless channels As a result various physical layer techniques
have been proposed in the literature for guaranteeing communication security
NOMA is viewed as a promising technique to provide superior spectral efficiency
by multiplexing information signals at different power levels [13] Hence it is
expected that NOMA can bring additional rate and robustness to enhance the
achievable rate in UAV physical layer security communications Consider a
scenario where a UAV acts as a relay to facilitate data delivery to two receivers
with different security clearance levels within a maximum cruising duration T The
receiver with a lower security clearance level and a higher potential with an
eavesdropper Since it has a strong motivation in intercepting signals intended for
a receiver with a higher security clearance Then when the eavesdropper suffers
from a bad channel condition NOMA is adopted to forward both confidential and
public information simultaneously Otherwise UAV only broadcasts the public
information for security issues The mode selection between NOMA and unicast is
20
chosen based on the results of the proposed resource allocation optimization In
particular for maximizing the spectral efficiency one needs to jointly optimize the
transmission scheme resource allocation and UAVrsquos trajectory However the
coupled optimization variables generally result in non-convex optimization
problems which are difficult to solve optimally As an alternative an iterative
suboptimal algorithm based on successive convex approximation can be employed
to facilitate a computationally efficient joint design We have discussed that the
NOMA scheme always outperforms OMA in all the considered scenarios which
demonstrates the spectral efficiency advantage brought by NOMA in striking a
balance between public data rate and confidential data rate
The main motive of this research is to enhance the inherently insecure PHY layer
of the NOMA-based UAV communication network NOMA-UAV communication
network requires feasible paring between trusted amp untrusted users (attacker) for
cooperative communication mainly in real-time field applications The power
allocation factor need to be optimized as per the trustworthiness of the associated
users (reliable user) and keeping the outage probability minimum for secured and
cooperative communications The pair Outage Probability and the SOP have been
optimized jointly for feasible pairing between BS amp the associated Users
18 Aim and Objective of the Research
The proposed works main objective is to examine the design of a NOMA-based
UAV communication network for enhanced Physical Layer security (PLS)
features Remarkably it is anticipated infrastructures and resources to connect
numerous devices and provide various services Researchers these days
concentrating on ways to design a heterogeneous framework like deployed small
cells air and ground-based deploy multifarious communication methods in 5G
such as millimeter-wave (mm-Wave) device-to-device (D2D) massive multiple-
input multiple-output (MIMO) Cognitive Radio (CR) and so on for improving
spectrum and energy efficiency
As a critical need especially for emergency applications the adoption of NOMA
transmission of UAV communication needs to be improved PLS A new optimal
resource allocation algorithm for some more robust and stable communication in
21
single and multiuser scenarios has been suggested here The PLS in dense
heterogeneous sensor networks has improved by the feasible pairing of trusted and
untrusted users (K Cao 2019 T Zhao 2018) In the instance of untrusted users
dynamic programming and POMDP are subjected to the channel conditions
details optimizing OP and SOP as a restricted parameter accompanied by resource
allocation (Davis 2018 L Hou 2018)
The main aim of the proposed research work areas
bull To analyze the underlying NOMA UAV communication framework with
enhanced Physical Layer security (PLS) implications for particular quest
applications
bull To examine the potential pairing of trusted and untrusted users in the
NOMA-based UAV contact network with two users and multiuser scenarios
for certain channel conditions called Channel State Information (CSI)
bull To maximize resource allocation among trusted and untrusted users by
pairing OP and Secret Outage Probability (SOP) as performance measures
with the POMDP optimization method
bull To evaluate POMDP and dynamic programming resource allocation with
two users and multiple users for both protected NOMA-based UAV
communication network scenarios
19 Thesis Organization
Chapter 1 Provides the introduction and basic concept of the proposed work with
the problem identification motivation and aim and objective of the proposed work
Here we described LTE 4G and its advanced techniques than about the NOMA and
its basic scheme UAV concepts represent their types and basic working strategy
Chapter 2 Provides a survey of the existing technologies which is related to the
proposed work The NOMA transmission schemes Merits and De-merits related
to security UAV assisted communication in heterogeneous sensor networks UAV
networks of 5G and beyond communications has been explained then about UAV-
NOMA PHY secured communication techniques as well
22
Chapter 3 Describes the proposed work of improvement of physical layer
insecurity of the NOMA The overflow and its performance measures with
simulated output have been defined in this chapter
Chapter 4 Describes Migrations proposed work from 4G LTE to advanced PHY
techniques for UAV communication The overflow and its performance measures
with simulated output have been explained in this chapter Concludes and explains
the proposed work with its outcome and the future scope of the proposed work
23
CHAPTER 2
LITERATURE REVIEW
21 Integration of UAV Networks for 5G and B5G communication
5G and B5G had been anticipated to give a unique connection among universal
users The UAV had been emerged for its advantage of wireless network and
relaying high data rate The UAV in the 5G and B5G was introduced and 5G and
B5G were updated with the new concept of Space-Air-Ground Integrated Networks
(SAGIN) Three layers were established named physical network communication
link and evaluation Besides the usage among the dense population IoT was
applied in satellite communication In which the IoT had provided the uninterrupted
service with high data rate communication The scope for flying UAVs had been
created for enhancing the number of mobile users with IoT (Ali et al 2018)
5G and B5G had projected the UAV as the vital constituent One to multiple point
transmission can be possibly advance in 5G and B5G The structural design of the
upcoming UAV (multi-tier drones) was driven by the routine of different structures
like the maximum functioning altitude communication overlap coverage and
determination The UAVs practicability (multi-tier drones) among conventional
UAVs (single-tier drones) is scrutinized in that perspective By ascertaining the
circumstances UAV (multi-tier drones) could supplement the older terrestrial
networks with RF Initially UAV (multi-tier drones) and drone-aided wireless
networks were related to finding the tasks The modified UAV (multi-tier drones)
and the drone-administered wireless networks were analyzed The enactments of
UAV (multi-tier drones) were scrutinized in the contest of spectral efficiency in the
downlink networks Their effect had exhibited the detailed network parameters The
UAV distribution (multi-tier drones) was considered advantageous for the spectral
efficiency from the downlink transmission over traditional terrestrial wireless
networks (Sekander et al 2018)
The growth of 5G and B5G wireless networks prominently hang on the
incorporation of the terrestrial and aerial systems in innovative heterogeneous
network architecture They had advanced a creative and tangible multiple UAV
24
made up of cluster UAV ndash base stations and Poisson point process with UAV and
mm-Wave frequency band Ground user equipment and UAV had exhibited as the
Poisson cluster process and then spread around the public cluster in the distinctive
cluster In particular the scrutiny was accompanied by the accumulation of extra
tiers Extra tiers were made up of multi-cluster UAV base stations and single ground
user base stations in the characteristic cluster Four-tier network systems were
designed correspondingly from the subdivision of the above-said base stations
Two-tier and four-tier association patterns were built for discovering the
involvement of the cluster networks The coverage probability for the downlink and
network throughput was derived (Ji et al 2020) The numerous subordinate title
role of the multifaceted communication systems was performed by the UAVs The
UAV was acted as the air relay in the maintenance of ground networks The UAVs
were used in the countryside hilly zones whereas the communication was
inadequate The author anticipated resolving the viable communication difficulty in
5G and B5G vehicular ad-hoc The associate communication pattern established on
the smart UAVs was planned given the crisis condition of the car ad-hoc The smart
UAVs were supporting the vehicular ad-hoc strong communication in real
situations Above and beyond its actual characteristics of the vehicular ad-hoc were
needed to be endangered to avoid the prohibited features from attaining and
exhausting for law-breaking practices Innovative UAV with a secret authentication
key arrangement was recommended in the 5G and B5G vehicular ad-hoc Because
of supporting efficiency the vehicle network which guaranteed communication
confidentiality was not negotiated The suggested pattern was confirmed to be
unaffected by numerous outbreaks by exploiting the broadly applied natural or
random ROR scheme
Furthermore the projected scheme had well calibrated the communication
overhead from the performance estimation (J Zhang et al 2020) The UANs had
obtained a phenomenal role in the research area the emergent sector of aerial
robotics The parcel transport organization monitoring occurrence shooting
surveillance and tracing were the metropolises general operations utilizing the
UAV Various domains would use 5G and B5G to improve UAV networks UAV
ecological unit was advantageous in present 5G and B5G mobile communications
For UAVs intrinsic features they were concerned for flexible movement of three-
25
dimensional space independent actions and smart locations These devices were
provided with extensive scope in cellular networks The author proposed an in-
depth assessment of implementing cooperation between UAV and 5G and B5G In
which UAV had been assimilated as a novel user equipment of aerial in present
mobile communications The UAV had implemented the duty of flying users within
the network coverage named the cellular-connected UAVs in this amalgamation
The author showed a broad examination of the incorporation tasks with 5G and
B5G novelties Continued efforts in the prototyping and validation of mobile
communication UAVs were conducted using the ground trial The paper had
focused on the current growth in 3GPP The social-economic had not been taken
into account which was considered disadvantageous (Mishra amp Natalizio 2020)
The UAV was anticipated as the significant constituent in the 5G and B5G wireless
networks 5G enables the UAV to be used in broadcasting and end-to-end
communications using the small UAV They needed a devoted and endangered
aerial spectrum in the aircraft cargo by letting small UAVs run in space in
supervisory authority The security information was obtained from the link Control
and Non-Payload Communications (CNPC) The security information contained
the regulation of UAV and the line of sight of terrestrial The CNPC application in
the 5G and satellite communication was scrutinized in this paper Payload
communication like mm-Wave networks and UAV were analyzed in this paper The
direction-finding and reconnaissance difficulties were examined UAV
communication systems were scrutinized and the hardware challenges were
discussed (Hosseini et al 2019)
The potential gain from the UAV-assisted data gathering was found in
indiscriminate IoTs The characteristic propagation was represented by utilizing the
complicated channel method (contained small- and large-scale fading) IoTs were
updated in constrain of transmit power (in high) and total energy The multi-antenna
UAV was selected in the IoTs in sequence The virtual MIMO was created by the
communication between UAV and singe antenna IoT in every transmission (W
Feng et al 2018)
The UAV was applied in the aerial coverage surveillance agricultural prediction
constructional areas and power line supervising and blood donation The flight
26
period increment payload capability fast movement and speedy placements were
implied features in the UAV so that the UAV was exploited by the applications of
5G and B5G (Ullah et al 2020)
The UAV was considered a motivation for many emergent usages and reformed
social-economic welfares The wireless networks for the UAV and the base stations
were desired for the UAV function Mobile communications were considered
suitable for finding tracing and regulating the flying UAV The wireless
communications were selected for their features of broad coverage quality of
service and secrecy The wireless communication in the UAV improved
productivity besides the line of sight (G Yang et al 2018)
22 UAV-NOMA in Physical Layer Security enhancement
The NOMA has been applied in the fifth generation (5G) technology The Multicast
Cognitive Radio (MCR) network is implemented using the NOMA and coined as
MCR- MOMA The transmission side is also included with the superimposition
code The decoding was applied at the receiving end So an unknown user is
deduced in their methodology (Meng et al 2020)
The physical layer security for the cooperative NOMA was examined Amplify
and forward decode and forward were taken into consideration for achieving
secure transmission (Chen et al 2018)
The physical layer security of the NOMA was analyzed in the broader network with
varying locality The single and multi-antenna were established in the following
cases The single antenna was taken for an end-to-end connection in a secured
manner And the multi-antenna was used for the connection of base station and
random user Finally achieved security for the multi-antenna on the transmission
side The security of the single antenna was attained by introducing the excluding
area for eliminating eavesdroppers The individual expression of security outage
probability for both single antenna and multi-antenna were derived (Yuanwei Liu
et al 2017)
The secure transmission of NOMA in large-scale applications was investigated
Stochastic Geometry was utilized for placing the eavesdropper and user nodes The
equation for secrecy outage probability was derived and expressed for evaluating
27
secure transmission Security can be improved by expanding the protected zone
(Qin et al 2016)
The power domain NOMA had the disadvantage of decoding data by other
unauthentic users of the same source For reducing unauthentic users the base
station should treat the unauthentic users with different cleaning methods The
secrecy outage probability was investigated for authentic users and unauthentic
users Both users were combined as a pair to the non-uniform distribution of original
and unauthentic users The pair outage probability of genuine users from the secrecy
outage probability restrained NOMA authentic users The derivation for pair outage
probability and the secrecy probability were expressed for calibration The
combined system had been the better security (ElHalawany amp Wu 2018)
The physical layer security was considered problematic in the wireless networks
mainly for keeping the authentic userrsquos data The UAV was acted as the base
station UAV based base station had sent the extensive data to the original users
NOMA with the multi-antenna with mm-Wave frequency band transmission had
enhanced the spectral efficiency The physical layer security was attained by
announcing the space around user locality as the eavesdroppers protected zone
Covering the entire eavesdropper area was considered a resource-consuming way
The shape optimization for the protected location in each UAV base stations
altitudes was introduced The derivations for the secrecy sum rate and the secrecy
outage probability were expressed (Rupasinghe et al 2018)
The vehicular communication system had used cooperative NOMA The secrecy
outage probability was considered in vehicular communication The relay can be
used in both modes (half-duplex and full-duplex) in vehicular communication The
closed derivation for the secrecy outage probability was expressed The security of
the full-duplex NOMA resulted better than that of the half-duplex NOMA The
limitations are that the velocity of the vehicles was not considered Figure 21 is
illustrated the conceptual model of the vehicular communication NOMA system
(Xie et al 2019)
28
Figure 21 Vehicular communication NOMA system
The physical layer security of the uplink NOMA of the large-scale devices was
examined The connection networks had investigated with the approach called
stochastic geometry The new derivation was expressed for the coverage
probability The protected zone restrains eavesdroppers to the authentic users
Efficiency secrecy throughput was examined wiretap channels and the many
original users Constant transmission and variable transmission were collectively
inspected The signal to noise and the movement to interference ratio were derived
drastically (Gomez et al 2017)
The wireless system was executed using Space-Time Block Coding (STBC)
approach in the NOMA of mm-Wave MIMO The technique focused on haphazard
users So the pairing method was introduced mainly for Random Near-Random Far
(RNRF) Here the latent period could be minimized and the RNRF has also been
deduced for the overhead issue The result revealed the systems efficiency with a
proper implementation (Ghavidel et al 2020)
The recent arbitrary beam forming method was proposed in the multiple access
NOMA The pairing had decided to the user places So the evaluation was focused
on the system overhead The result revealed that the proposed work outperformed
29
the existing methods (Aghdam et al 2020) NOMA enhances the reliability of
multi-users transmission The sum rate could be reduced for improving Quality of
Service (QoS) power transmission and signal outage probability The
eavesdropper easily accessed the multi-access systems that cause physical security
during transmission (Z Li et al 2020)
The NOMA had provided spectral efficiency speed transmission of data multiple
networking and less latent period The NOMA utilizes the power domains for
various access Cognitive Radio Networks (CRN) is used to screen illegitimate
users The legitimate users were only permitted in the CRN by the Primary User
Networks (PUN) QoS The cooperative NOMA here implemented with the PUN
and the system performance is enhanced The spectral efficiency can be improved
by the secured transmission The cooperative NOMA was additionally developed
in the CRN with the PLS A new method of cooperative NOMA in the CRN was
examined The PUN technique attains a secure transmission Multiple antennae
were used in this study for reliability and the eavesdropperndashexclusion zone method
is used for better security (B Li et al 2018)
The downlink NOMA for moderate CSI was examined The challenge of the power
domain was rectified by allocating power NOMA The power in NOMA and that
of the OMA was analyzed which resulted in a significantly reduced NOMA (Cui
et al 2016)
Here the users were multiplexed by the power domain So the method was coined
as power domain NOMA The demand arising from the B5G (Beyond 5
Generation) had reached using power domain NOMA Machine learning in the
NOMA was described (Maraqa et al 2020)
The uplink NOMA with the PLS was proposed The uplink NOMA contained a
single base station and multi-users a couple of users combined for NOMA The
known jammer emitted the pseudo-noise to divert the eavesdroppers The study had
suggested the two jammers in the uplink NOMA for secure transmission (N Zhao
et al 2020)
The Intelligent Reflecting Surface (IRS) is designed using downlink NOMA The
multi-access had used the space direction of the beams of closure users The IRS
30
had performed the multi-access for every spatial order by the cell edge users of the
orthogonal beams (Ding amp Poor 2020)
The multi-input single-output NOMA has introduced the technique called Secrecy
Beam Forming (SBF) SBF had utilized the artificial noise for NOMA security
aided users in which the eavesdropperrsquos channels deteriorated The SBFs secure
transmission can be achieved in which high successive interference cancellation is
gained (L Lv et al 2018)
The superposition coding was performed in the transmission pat The successive
interference cancellation was conducted in the receiving position These two
techniques were combined in the novel 5G aided NOMA The basic concepts of
uplink and downlink NOMA were mentioned The dominant condition was
performed in the two user clusters of NOMA The prevailing state had issued the
confirmed spectral efficiency gain in NOMA (Tabassum et al 2016)
The relay scheme in IoT was examined for the secrecy of NOMA This was coined
as relay selection NOMA The base station had transmitted the secret messages to
the two NOMA-aided sensors and eavesdroppers IoT had treated the sensors and
eavesdroppers with different power allocations The expression for certain outage
probability and the strictly positive secure capacity was derived Increasing the
number of the relay would enhance the security in the NOMA-aided IoT The
outage probability for NOMA and OMA were compared The NOMA resulted in
better outage probability in Decode and forward mode (Do et al 2019)
31
Figure 22 RS-NOMA against an external eavesdropper
The NOMA-aided IoT was utilized to fight against the external eavesdropper as
Figure 22 The secured NOMA was proposed The base station sent secret
messages to several authentic destinationsmdashseveral eavesdroppers and unauthentic
users
Nakagami-m fading model was carried out using the multiple antennae in the
channel The security was attained using the max-min transmit antenna selection
scheme Both authentic and unauthentic eavesdroppers were analyzed The closed
derivation for the cumulative distribution of the original user was expressed first
That was compared with the unauthentic user The derivation for the secrecy outage
probability was obtained to identify the level of secrecy performance (Lei et al
2018)
Reconfigurable intelligent surface (RIS) aided NOMA was established for the
secrecy performance The main disadvantage of this model was the chance of using
RIS by the eavesdropper The secret outage probability was derived in this paper
The RIS improved the secrecy of the traditional NOMA The eavesdroppers were
limited from receiving the RIS signal by enhancing the number of intelligent
elements in the RIS A high signal-to-noise ratio was obtained from this experiment
(Liang Yang amp Yuan 2020)
32
The cooperative relaying NOMA was proposed for improving private transmission
in wireless networks Full duplex mode transmitted the jamming signals That
received the required communication at first Secondly the jamming signal
emission was sent by the base station The power allocation for the jamming signal
and information signal was decided on the eavesdropper channel state information
The eavesdropper was jammed by the signal from the first phase with maximum
power Second the derivation of the secrecy outage probability was expressed by
static eavesdropper CSI (Y Cao et al 2020)
The NOMA achieved spectral efficiency and secrecy The security of the multi-
NOMA users was obtained by the successive interference cancellation (SIC)
decoding in the receiving node The conservation of the untrusted NOMA was
concentrated in this study The security can be confirmed by the properly secured
decode processing and allocating power The decoding scheme was implemented
for aiding NOMA users The decoding was performed for enhancing the sum-rate
(Thapar et al 2020) The cognitive radio network in NOMA with the external
eavesdropper was proposed (Mehr et al 2020)
The cooperative NOMA was used in the field of energy harvesting communication
The novel relaying technique was introduced for achieving secrecy The secrecy
outage probability was derived and the derivation was expressed for the three
conditions The first condition was the derivation of CSI with a passive
eavesdropper The second condition was the derivation of CSI with the unauthentic
eavesdropper The third condition was the derivation obtained from the multi-relay
nodes The increased SNR resulted in high security The increase in the number of
users deduced security This was considered a disadvantage (Salem et al 2020)
Satellite communication covered more range of broadcasting So the security
challenge was considered a big difficulty in satellite communication Downlink
NOMA was assessed with an eavesdropper for the examination of secrecy The
paper concentrated on the physical layer security of downlink satellites Here two
methods were proposed The frequency-domain NOMA was considered for gaining
spectral efficiency The multiple user interferences were obtained in the process of
overlapping Introducing a suitable technique can be performed the security for the
number of users The secrecy rate was analyzed for all authentic users (and the
33
eavesdropper) and expressed in the derivation The safety was improved using the
spectral overlap method (Yin et al 2019)
The NOMA was considered as the emerging scheme in the upcoming wireless
networks The secrecy sum rate for the downlink NOMA (with MIMO multiple
inputs multiple outputs) was examined Downlink NOMA had the base station
number of users and the eavesdropper In the limitation of transmit power and
optimal successive interference cancellation the security was expected to enhance
Downlink MIMO NOMA was considered advantageous because of its secrecy
performance and the practical usage of bandwidth The mutual information rate and
the mean square error were causing the secrecy rate optimization to the problem of
biconvex This was rectified through the alternative optimization method and the
second-order cone programming was solved (Tian et al 2017)
Table 21 Comparative analysis
The comparative analysis for the physical layer security was examined in existing
studies
SR
No
Details of Author wise Contribution to NOMA Technology
1 Author (YFeng Yang amp Yan 2017) Secrecy performance in NOMA was
conducted with the help of artificial noise in the full-duplex mode of relaying
Methodology The optimization of the power was calibrated for the source
information and the noise signal The closed derivation for the secrecy outage
probability was expressed
Usage and limitations The physical security was increased
34
2 Author (He Liu Yang amp Lau 2017) NOMA was developed in the constrain
of security
Methodology The secret message had been sent to some users and also to the
eavesdropper The Novel decoding process was conducted for excluding the
unauthentic users The iterative algorithm was used for power optimization
Usage and limitations Transmit power was reduced The quality of service
was availed
3 Author (D Wang et al 2020) The secrecy was performed in the NOMA
The security was developed against the eavesdropper outside
Methodology The channel state information was analyzed for secrecy The
quantization of CSI had performed for secrecy The derivation for the secrecy
and transmission outage probabilities were obtained
Usage and limitations The secrecy rate was enhanced
4 Author (L Lv et al 2020) The physical security of the NOMA was
improved by adding artificial noise jammer and inter-user interference The
mode of full-duplex in the updated version was used in the NOMA
Methodology The eavesdropper can be trapped the superimposed signal from
the source So the secrecy was affected
Usage and limitations The spectrum usage is effective in the NOMA
transmission scheme Numerous connections can be performed in the NOMA
NOMA is considered to be the most advantageous for the upcoming
generation communications The superimposition technique was followed
4 Author (Yue et al 2020) Secrecy performance of the NOMA was developed
with a unique framework
Methodology The eavesdroppers inside the zone and outside the coverage
zone were examined properly in this paper The outage probability for codendash
power domain NOMA was derived
Usage and limitations Safety was acquired for both internal eavesdropper
and external eavesdropper in this scheme
35
5 Author (Guezouli et al 2020) The heterogeneous sensor network of cellular
communication was taken into account
Methodology Unmanned aerial vehicles are utilized the heterogeneous
sensor network of cellular communication
Usage and limitations Extended the life span of the network system The
cost of the hardware components is drastically low The random and the
repeats in the speedy movement The latency is maximized The coverage
period is maximum
6 Author (Yao amp Xu 2019) The security in transmitting a large amount of
information in the wireless network systems are analyzed with unmanned
aerial vehicle UAV
Methodology The numbers of UAVs are arranged in the space The base
station sent the information to the UAV in the space The authentic receivers
have obtained the secured information from the UAV The HPPP
homogeneous Poisson point process is used for distributing the authentic
receiver and eavesdropper in the line of sight
Usage and limitations The increase in the number of safety zone causing the
secured transmission
7 Author (Saacutenchez et al 2020) Physical security can be achieved by the
method of a unique encryption scheme
Methodology The physical layer security of the following schemes is
discussed in this paper mm-wave NOMA massive multi-input multi-output
heterogeneous sensor networks full-duplex mode
Usage and limitations The physical layer security was analyzed for the 5G
supporting technologies Good reliability achieved The less latent obtained
Machine-type communications can be enabled
36
8 Author (Hou et al 2018) The multi-antennas were used in NOMA with
UAV The stochastic geometric approach was examined
Methodology The multi-input multi-output kind of NOMA was utilized In
common the stochastic geometric approach was used for drastically moving
NOMA
Usage and limitations The maximum signal-to-noise ratio was obtained in
this scheme Power optimization was achieved The path loss is less Good
spectral efficiency was obtained
9 Author (Miao et al 2020) The broadcast type of communication was
performed The less weighed three-dimensional space for 5G communication
was analyzed
Methodology Both the performances of multicast and broadcast were
enabled UAV-assisted 5G communication systems are emerging in the
upcoming wireless networks
Usage and limitations Better flexibility in the network Continuous mobility
One lined line of sight
10 Author (Majhi amp Mitra 2020) The secure communication in cognitive radio
by NOMA was propounded
Methodology The antenna strategy of giving minimum outage probability
was concluded from this study
Usage and limitations The limitation is that more spectral efficiency causes
security issues
11 Author (X Zhao amp Sun 2020) Secure communication of the physical layer
in Visible light NOMA Communication was proposed
Methodology Energy optimization in security constrain was propounded for
achieving overall performance
Usage and limitations It is difficult to find optimal results because energy
optimization is the nonconvex issue
37
12 Author (Tuan amp Hong 2020) Secure communication in simultaneous
wireless information and power transfer NOMA was remitted
Methodology Eavesdropper is used for security purposes between the user
and base station using energy relays Known jammer is used for secure
transmission For energy efficiency storing and transferring were propounded
Usage and limitations Jamming requires extra power allocation
13 Author (Vaezi et al 2019) NOMA for 5G in mmWave MIMO cooperative
and cognitive were analyzed in this study
Methodology SWIFT NOMA is useful for weak receivers
MIMO using more antenna
Usage and limitations multi-antenna utilization cause high power
consumption
14 Author (Vaezi et al 2019) Mobile edge computing NOMA was proposed to
optimize power
Methodology Minimum latency and less power consumption
Usage and limitations Transfer power allocation must be calibrated
15 Author (Faraji-Biregani amp Fotohi 2020) Security in UAV communication
was proposed by introducing mobile agents
Methodology Malicious user of UAV was identified
Usage and limitations Three-phase power is essential
16 Author (G Zhang et al 2019) Secure communication in 5G UAV was
propounded by joint trajectory carrying out in physical layer
Methodology Power optimization was proposed for security
Usage and limitations Security in the physical layer was achieved by
optimization of trajectory
17 Author (Fotohi et al 2020) Agent-based self-protection was propounded in
UAN for secure communication
Methodology This method imitates the immune system of human beings
Less cost
Usage and limitations Energy is not optimized properly This approach
needs to consider other malicious attackers
38
18 Author (Shang Liu Ma amp Fan 2019) Vehicle to everything approach was
propounded for security in a UAV
Methodology Security of vehicle to the vehicle was proposed by considering
eavesdroppers active and passive attacks
Usage and limitations High price
19 Author (Kantor et al 2017) The flight path was calibrated in a UAV
Methodology Security performance was achieved by encryption as well as
anonymization
Usage and limitations High in cost and hardware structure occupies more
place
23 Research Methodology
The NOMA-based cellular architecture for UAV communication has been
considered here as reference network architecture Rayleigh fading has been
assumed as a channel characteristic The performance parameters for PHY layer
security are (1) Pair Outage probability (Pair OP) between two users trusted near
user designated as U1 and untrusted far user designated as U2) and (02) Secrecy
Outage Probability (SOP) of trusted near user designated as U1 The aim is to
achieve optimal Pair OP for the given constrained SOP of User U1 so that network
resources can be efficiently allocated to both users without compromising the
secrecy of trusted User U1
The mathematical analysis from reference literature (ElHalawany et al 2018) has
verified and supported the joint optimization of the Pair OP and SOP for the given
power allocation factor in NOMA This research work is extended as providing
more efficient resource allocation using the POMDP algorithm in a given scenario
First the varying distance of untrusted user U2 from BS as a critical selection
parameter that affects Pair OP amp SOP of user U1 and U2 both has been simulated
and the feasible and infeasible pairing of both users have been analyzed The
optimal power allocation factor for feasible pairing as the constrained problem is
optimized by opting for POMDP as a resource allocation algorithm wherein the
SOP of user U1 is strictly maintained for given CSI POMDP provides optimum
39
power allocation factor for trusted and untrusted users pairing as shown in the
proposed flow of POMDP algorithm is used to model a variety of real-world
sequential decision-making problems After the BS has been set up the distance
between the BS and the user is calculated and if space is less than 200m it is
defined as a trusted user While if the range is more than 200m it is described as
untrusted users In the case of trusted users the channel state information (CSI) is
provided to the proposed algorithm POMDP for reliable and efficient resource
allocation
24 Summary
UAVs play a central role in providing network service recovery in a disaster-
stricken region enhancing public safety networks or handling other emergencies
when Ultra-Reliable Low-Latency Communication is required In particular UAV-
assisted communication can be regarded as an important complement to the 5G
cellular networks Surveyed literature related to UAV communications published
over the past several years emphasized the cybersecurity and channel modeling for
UAV communications etc Security is one of the critical issues in communications
Modern communication networks are based on the layered architecture from the
physical layer up to the application layer A great deal of effort has been made to
develop the cryptographic protocols above the physical layer However the
physical layer is not as robust as that in wired communications The physical layer
in wireless communication is more complex than the counterpart in other
communication paradigms The concerns come from not only the noises but also
many types of fading Recently there has been an influential interest in studying
the security issues in the physical layer Security is highlighted as another
challenge and the implementation of physical layer security techniques is seen as
a difficult task PHY security in NOMA systems under the presence of external
eavesdroppers or untrusted relay nodes Upcoming 5G networks for unpredicted or
crisis (disaster management) the placement of terrestrial substructures is
economically infeasible and challenging due to high operational expenditure as well
as sophisticated and volatile environments
To address such novel issues intelligent heterogeneous architecture by leverage
UAV has been well-thought-out to be a promising novel model For advancing the
40
performance of the UAV 5G communication system physical layer techniques are
of many effects as they have impacted the applications of UAVs Security of
NOMA-based UAV communication network has been scrutinized for optimization
as physical layer security
41
CHAPTER-3
SYSTEM MODEL FOR NOMA-UAV
COMMUNICATION
31 NOMA-UAV System Secured Communication for 5G
NOMA is visualized as a hypothetically capable method for addressing some
dangerous tasks in the 5G networks namely massive connectivity and spectral
efficiency (He et al 2017) Two leading NOMA solutions which are channel
estimation multiplexing and code domain multiplexing have been recommended
for future networks Various users are assigned different power levels as per their
channel conditions with power domain multiplexing and the consecutive
cancellation of interference is being used to cancel multiuser interference Here the
different users are allocated other systems for code domain multiplexing eg space
code multiple access and then combined with the same frequency resources
NOMA output with organized users was examined in (Ding et al 2014) From an
equality standpoint the layout question of the NOMA method was discussed in
(Timotheou amp Krikidis 2015) To boost machine reliability cooperative NOMA
schemes were explored (Choi 2014) Multiple-Input Multiple-Output (MIMO)
techniques were made known to systems of NOMA in (Choi 2015) that provide
additional spatial flexibility
311 The basic scheme of NOMA
The NOMA system allowed several users to be served simultaneously by the
transmitter To transfer a linear combination of different signals towards the
recipient the system of proportional representation superposition coding (SC) The
transformed signal is provided through
σ ඥ119875119896 119878119896119870119896 =1 -------------------------------------- (1)
Where 119927119948 represents the transmit power assigned toward user k th
119930119948 indicates the normalized message used for user k th
42
The instantaneous total converses power is σ 119927119948119922119948=1 The received signal at user kth
and the eavesdropper are offered through
119910119896 = ℎ119896 σ ඥ119875119896 119878119896119870119896=1 + 119899119896 -------------------------- (2)
119910119890 = ℎ119890 σ ඥ119875119896 119878119896119870119896=1 + 119899119890 -------------------------- (3)
Where 119951119948 and 119951119942 indicated the zero-mean Additive White Gaussian Noise
(AWGN) at user k th with variance 1205901198962 and the zero mean AWGN at eavesdropper
with variance 1206481199422 respectively We assume that the noise variances at all the users
are identical
ie 12059012 = ⋯ = 120590119896
2 = 1205901198902
As per NOMAs process the SIC is followed by all users to decrypt the message to
the same decoding order Notice that it is not known what the optimal decoding
order is for the NOMA method that corresponds to secrecy
Therefore the mth message to be encoded to the user might not be the mth message
to the user As such we also have to add the π variable For example if 120587(1) =
3 then the first message to be decoded for the SIC is the message for the user 120645(119947)
forall j lt k before decoding its letter to remove the inter-user interference successively
Then the user 120645(119948) denotes its message while treating the news for all the user
120645(119946)foralli gt k as the interferences The received Signal-to-interference-plus ndashnoise
ratio (SINRs) at user 120587(119896) k lt K and user 120587(119870) to decode their messages are
respectively given by
119878119868119873119877120587119896=
120574120587(119896)119875120587(119896)
1+120574120587(119896) σ 119875120587(119894)119896119894=119896+1
119896 lt 119870 --------------------(4)
119878119868119873119877120587119870= 120574120587(119870)119875120587(119870) --------------------------------------(5)
Were 120574120587(119896) =หℎ120587(119896)ห
2
1205901199062
൘
43
Also the acknowledged SINR at user 120587(119898) to decrypt the message 120633120645(119948) 119896 lt
119898 le 119870 is given by
119878119868119873119877120587119896=
120574120587(119898)119875120587(119896)
1+120574120587(119898) σ 119875120587(119894)119896119894=119896+1
kltmle 119870 --------------(6)
Similarly the acknowledged SINRs by the eavesdropper of the message 120575119896 119896 lt
119870 and the message 120575119896 are respectively given by
119878119868119873119877120587macr
119896=
120574119890119875120587(119896)
1+120574119890 σ 119875120587(119894)119896119894=119896+1
klt119870 ----------------- ------(7)
119878119868119873119877120587macr
119896=
ȁℎ119890ȁ2119875120587(119896)
1205901198902 = 120574119890119875120587(119896) klt119870 ---------------------(8)
Where 120574119890=ȁℎ119890ȁ2
1205901198902൘
Notice that here expressions for the obtained SINRs at eavesdropper overestimate
the skill of eavesdropper Here a worst-case inference from the viewpoint of
legitimate users is made That is the messages have already been decrypted by the
eavesdropper for all users π (j) forall j lt k before attempting to decrypt the message
for the user π (k)
The presumption also assumes that the decrypting order and power distribution are
understood by the eavesdropper The eavesdropper may or may not recognize the
decoding order of the users and the allocation of power may or may not recognize
the messages for all users π (j) forall j lt k before attempting to decode messages for
users π (k) However since the eavesdropper has been unable to alert the authorized
customers of its capacity and the current CSI the approved user would be unable
to know the eavesdroppers details Therefore we have to pursue the worst-case
scenario for the permissible users point of view due to the liberality required by the
safety reports It highlights that the worst-case assumption in the study and design
of transmission schemes with secrecy requirements has been generally adopted
The proposed study has been evaluated using performance measures Here we
analyze NOMA with downlink and uplink networks suggested by SINR and Sum
44
Rate survey High SNR is then simulated to contrast the OMA and NOMA
processes
312 Downlink of NOMA
The Downlink of the NOMA network on the transmitter side is described in Figure
31 SIC method is supposed to be carried out successively on the receiver side of
each user until another signal is restored The coefficients of users are owed in an
inversely proportional manner based on their available bandwidth
Figure 31 Downlink NOMA network
A consumer with a poor available bandwidth has a transmission capacity of a
higher range than a consumer with strong available bandwidth As a consequence
the consumer with the higher power assumes the signals of other users to be noisy
and automatically restores the signal without conducting any SIC operation The
receiver of each consumer detects indications that are stronger than those of the
desired signal These impulses are then deducted from the power and this process
continues until the signal has been calculated Both users decrypt their signaling by
considering other users with lower correlations The signal is calculated as
45
119904 = σ 119886119894119875119904119883119894119871119894=1 -----------------------------------------------(1)
Where Xi is the user ithrsquos information through unit energy
Ps is the capacity of transmission at the BS
ti is the coefficient of power assigned for user i
Although without the need for lack of generality the channel profits are expected
to be graded as ȁℎ1ȁ2 le ȁℎ2ȁ2 le ⋯ ȁℎ119871ȁ2
Where 119945119923 is the coefficient of the channel of the user Lth
The received signal of the Lth user is calculated as
1199101 = ℎ119897119904 + 119899119897 = ℎ119897 σ ξ119886119894119875119904119883119894119871119894=1 + 119899119897 -----------------------------(2)
Where n1 is zero mean Complex Gaussian noise with a variance of 1206482SINR
analysis with the equation (2) the SNR of Lth user to identify the user 119895 le 1with
119895 ne 1
119878119868119873119877119871 = 1198861120574 ȁℎ1ȁ2120574ȁℎ1ȁ2൘ σ 119886119894 + 1119871
119894=119871+1 ------------------------(3)
Where 120632 = 1198751199041205902ൗ represents the SNR
Sum rate analysis After identifying the SINR of the downlink the sum rate will
also be done quickly
The NOMAs downlink data rate of Lth user can be calculated as
1198771119873119874119872119860minus119889 = 1198971199001198922(1 + 119878119868119873119877119871) --------------------(4)
313 Uplink of NOMA
The Uplink NOMA is depicted in Figure 32 where each user sends a signal to the
BS SIC iterations are supported to classify the signals of mobile users If both
channels are identical and BS sends the coefficients of power allocation to mobile
users the received signal can be interpreted as a synchronous uplink to the NOMA
46
119955 = σ ℎ119894ඥ119886119894119875119909119894119871119894=1 +n ----------------------------------(5)
Where hi is the coefficient of the channel for the ith user
119927119961119946 is the extreme transmission capacity supposed to be general to all users
N is zero-mean Gaussian noise with a variance of 1206482
Figure 32 Uplink NOMA
Analysis of SINR The BS decrypts the signals of the users as per the coefficients
of the users and the SINR for the Lth user can be defined as
119878119868119873119877119871 = 119886119897120574ȁℎ119897ȁ2120574 σ 119886119894ȁℎ119894ȁ2 + 1119897minus1
119894=1൘ ----------------------------(6)
Where 120574 = 1198751205902ൗ indicates SNR
Analysis of Sum rate The sum rate of uplink NOMA when 120632 minus infin can be
computed as
119877119904119906119898119873119874119872119860minus119906 asymp 1198971199001198922(120574 σ ȁℎ119897ȁ119871
119894=1 2 ------------------------ (7)
47
314 Comparison of NOMA and OMA
The attainable data rate of the Lth user of OMA intended for both uplink as well as
the downlink is estimated as
119877119904119906119898119874119872119860 = σ 120572 1198971199001198922120574(1 +
120573119897ȁℎ119897ȁ2
120572119897119871119894=1 ) --------------------------(8)
Just for convenience two users should evaluate the summation of uplink rates for
NOMA and OMA The use of both the uplink rate of NOMA and OMA at high
SNR can be calculated as---
119877119904119906119898119873119874119872119860 asymp 1198971199001198922(120574 ȁℎ1ȁ2 + 120574ȁℎ2ȁ2 ------------------------- (9)
equation (7) and (8) it is seen that 119877119904119906119898119874119872119860 le 119877119904119906119898
119873119874119872119860
Here we note 119929119956119958119950119926119924119912 le 119929119956119958119950
119925119926119924119912 shows that NOMA performed better than OMA in
terms of sum rate in both downlinks as well as uplink of two user networks
The sum rate will be calculated after the SNR as the formulation is shown In this
proposed work multiple users are propagated to the process of NOMA and here a
comparison of NOMA as well OMA has been defined The NOMA uplink and
downlink using the OFDMA method for the
32 PLS performance metrics in NOMA -UAV communication
This chapter mainly describes the proposed work to examine the availability of the
outage probability of the pair below an authorized user According to the decryption
of SIC availability and spectrum sharing the unauthorized user can function as an
eavesdropper and obtain an outage probability (OP) for all situations with the
Secrecy Outage Probability (SOP)
321 SOP and OP - two user and multi-user NOMA system
NOMA system has the capability for assigning multiple data over the transmission
signal through high-level coding (Shim amp An 2018) Thus it contains spectrum
efficiency when opposed to OMA But this has a limitation in security As an
48
instance if the eavesdropper is reached then it obtains multiple user data in the
interference of the NOMA signal Thus the security issues are more significant in
this system Here PLS is an available method to rectify the attack intended for
malicious users (Dai et al 2015)
Additionally data should be transmitted confidentially if the root and eavesdropper
networks can be evaluated and the recipient can decrypt the received text At the
same time the eavesdropper is not able to solve the text that has been interrupted
PLS is at the cutting edge of wireless communication security technology to prevent
eavesdropping attacks The SOP is described as the likelihood that the near users
attainable device confidentiality capability will fall under the predefined target
confidentiality rate as set out in (Shim et al 2017)
Through SOP we can calculate the level of protection of the device As an example
the low-secret OP system makes the system more stable in terms of security than
the high SOP system To boost the efficiency of the PLS CSI-based opportunistic
scheduling links to a scheduled destination in a particular time slot It has been
documented as an enticing scheduling scheme (Long Yang et al 2016) because the
various wireless channel has been exploited Opportunistic scheduling is also
considered to be one of the strategies used to increase the confidentiality efficiency
of the NOMA method
322 System Model
Suppose a multi-user NOMA system of downlink containing BS a selection of K
nearer users as N= 119873119894ȁ12 119870 and a range of M far users as F=
119865119895ȁ12 119872 and an eavesdropper E as displayed in Figure 33 More
specifically nearer users should make active use of the SIC methodology to
distinguish far user F Both the legitimate and illegitimate receivers are furnished
through a single antenna and operate in a half-duplex manner
49
Figure 33 Multi-two user architecture of NOMA system (Shim amp An 2018)
Here 119945119935119936 and ȁ119945119935119936ȁ2
Where X120598ሼ119878ሽ 119884120598119873 cup ሼ119864ሽ represent the channel coefficient and the corresponding
channel gain of the X-Y value
Taking into consideration that each wireless channel for Rayleigh block fading 119945119935119936
can be incorporated as an independently distributed random Gaussian variable with
zero mean and affirmative ℷ119935119936 Variance The outcome of channel gain ȁ119945119935119936ȁ2is an
exponential variable randomly through the Probability Density Function (PDF)
119891ȁℎ119883119884ȁ2(119911) = ቀ1
ℷ119883119884ൗ ቁ 119890119909119901 (minus 119911
ℷ119883119884ൗ )
if zge 0 119900119905ℎ119890119903119908119894119904119890119891ȁℎ119883119884ȁ2(119911) = 0 -----------------(1)
Especially the average channel profit can be represented as
ℷ119883119884= ൬119889119883119884
1198890൘ ൰
minus휀
ℒ ------------------(2)
When 120027 is the attenuation of the received signal 119941119935119936 signifies the distance among
X and Y 1199410 indicates the space and 120656 is the exponent of the path loss It is believed
that the source is entirely familiar with the CSI of both legitimate users and
eavesdroppers
50
323 Partially Observable Markov Decision Process-POMDP
Figure 34 Flow Diagram of the proposed system
The proposed overflow is shown in Figure 34 After the BS has been set up the
distance between the BS and the user is calculated and if space is less than 200m
it is defined as a trusted user While if the range is more than 200m it is described
as untrusted users In the event of untrusted users the channel state information is
accessible to the POMDP accompanied by the allocation of resources The study
was carried out after the machine operation Here a NOMA-oriented cellular setup
provided with a BS at the Centre and two users was described in Figure 35
51
Figure 35 Near and Far User
The adjacent user has a high level of security confirmation needed to protect the
layer since the low-security clearance user is situated at a distance away from the
BS P is specified as the highest level of transmitting power In this chapter it is
presumed that all DNS servers are furnished utilizing an individual antenna and all
channels are supposed to be individually static identical to the Rayleigh
dissemination concerning distribution
119862119873(0 120575119898
minus120572
212059601 2Τ
)
In which 120633119950 is the range between the BS and the nodes 119932119950 Here the path-loss
exponent and constant are defined as 120630 and 1206540 Furthermore BS is assumed to
have predicted the position of the user so that a better CSI can be obtained at BS
that is elaborate in user pairing
The BS transmits the superimposed mixture
119909119905 = ඥ1199051199041 + ඥ1 minus 1199051199042 ------------------------------- (3)
In which 1199561 and 1199562 are the unit of power signals received by users 1199321 and 1199322
respectively t is the power allocation coefficient for the adjacent user
1199031 = ℎ1119909119905ξ119875 + 1198991 ------------------------------- (4)
1199032 = ℎ2119909119905ξ119875 + 1198992 ----------------------------------(5)
Where 1199451119886119899119889 1199452 the channel profit link with the fading of small scale since the
BS to the user 1199321 and 1199322 respectively The additional Gaussian noise with variance
52
is denoted 1199511 119886119899119889 1199512 and zero mean 119894119904 119889119890119899119900119905119890119889119886119904 (1199250) and it is assumed
that the BS conveyed SNR is 120646 = 1199271199250
ൗ
In the NOMA technique additional users with more power may decode their signal
by recognizing the adjacent signal as noise without decoding the adjacent user
message In the previous equation 1198801 is supposed to first solve a weak signal by
decoding its own SIC signal1198802 which is an unauthenticated user attempted to
decrypt the nearer user text after decrypting the adjacent usage text after decoding
its own SIC message The following equation has therefore been achieved
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2 ----------------(6)
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ1ȁ2+1120588 and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2 ----------------(7)
119879119900119905119886119897119904119894119899119903 = 11987811986811987311987721 1198781198681198731198771
1 119878119868119873119877221198781198681198731198771
2 -----------------(8)
Where 119930119920119925119929119950119951
indicates the SINR ratio of user mth that was decoded by 119932119951 for
119898 119899 isin ሼ119894 2ሽ and the channels gain followed an exponential distribution with the
parameter 120649119950=120654120782120633119950minus120630
324 Problem formulation
As a result the BS could achieve and provide better communication for users who
are vulnerable to security threats from unauthenticated users the proposed
framework identified two kinds of QoS energy efficiency that could be considered
essential for addressing the problem In a particular study a pair of OPs was
specified to check the reliability at which the attainable data rate for users is equal
to or greater than the threshold of minimum reach The following issue aimed at
reducing the pair OP to an SOP factor intended for the user 119932120783 that is provided by
Where 1199270is Outage Probability- (OP)
1199271 is Secrecy Outage probability user U1 119930119926119927(119932120783) and
120631 the permissible SOP threshold
53
33 Performance Analysis Improving PLS Insecurity of NOMA
System
331 The Pair OP Calculation
Through Shannons capacity formula and assuming 119914120783119957119945 119886119899119889 119914120784
119957119945 as the
threshold capacities of users 119932120783 119886119899119889 119932120784 respectively the combination of OP
could be offered by
119927119954 = 120783 minus 119928120783119961119928120784 in which 120649119950 = 120784119940119950119957119945
119950 isin ሼ119946 120784ሽ -------------(9)
empty120783 =120649120784
120646(120783+119957+120649120784119957) empty120784 =120649120783
120646119957
119928120783 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ 120782 lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 ------------------------(10)
Case 1empty1 gt empty2 for having the limitation of the allocation of power factor (t)
required to be satisfied (tgt120649120783
120649120783+120649120784+120649120783120649120784) and for this case 119928120784 could be attained as
follows
119928120784 = ൝119942119961119953 ቀ
minusempty120783
120649120784ቁ
120649120783
120649120783+120649120784+120649120783120649120784lt 119957 lt
120783
120783+119955120784
120782 119952119957119945119942119955119960119946119956119942 --------------(11)
Case 2 empty1 lt empty2 Like case 1 it was stated that the opposite constraint depends
on
t gt 1206491
1206491+1206492+12064911206492 and 1199282 can be evaluated as follows
119928120784 = ൝119942119961119953 ቀ
minusempty120784
120649120783ቁ 120782 lt
120649120783
120649120783+120649120784+120649120783120649120784
120782 119952119957119945119942119955119960119946119956119942 ---------------------(12)
54
Table 31 List of parameters
Parameters Description
N Number of nearer users
M Number of far users
E Eavesdropper
ℎ119909119910 Channel coefficient between 119909119905ℎchannel and 119910119905ℎ users
119889119883119884 The distance among x and y
1198890 Space
120598 An exponent of the path loss
ℒ Attenuation of the received signal
120575119898 the range between the BS and the nodes
1205960 Path loss constant
120572 Path loss exponent
1199041 1199042 Unit of power signals received by users 1198801 and 1198802
T Power allocation factor for the adjacent user
ℎ1119886119899119889ℎ2 Channel coefficient of 1198801 and 1198802with the fading of small
scale
11989911198861198991198891198992 Gaussian noise variance
1198730 Zero mean for Gaussian noise
120588 Signal to noise ratio
119878119868119873119877119898119899
Signal to interference noise ratio of users n and m channels
55
120591119898 Exponential distribution parameters
1198750 Pair of OP
1198781198741198751 119878119874119875(1198801)
120573 The permissible SOP threshold
Table 31 depicts the list of parameters used in the proposed methodology which
are useful for assigning and the values are assigned based on the parameters given
for the experimental evaluation as well This chapter concludes with the basic and
the actual flow of the proposed method to know more about the work in the
simulation process
332 Pseudo-code for the proposed algorithm
Algorithm I
Step 1 Estimate Rayleigh distribution
119862119873(0 120575119898minus120572 2Τ
1205961199001 2Τ
) where
120633119950 is the distance between nodes 119932119950 and the BS
120630 is the path-loss exponent and
120654119952 is the path-loss constant
Step 2 The BS broadcasts the superimposed mixture and input signal as follows
119909119905 = ξ1199051199041 + ξ1 minus 1199051199042
Where 119956120783 and 119956120784 are the unit power signals received by users 119932120783 and 119932120784
respectively 119957 is the Power allocation coefficient for the near user
Step 3 The received signal is as follows
1199031 = ℎ1119909119905ξ119875 + 1198991
1199032 = ℎ2119909119905ξ119875 + 1198992 where
56
119945120783 and 119945120784 are the channel gain associated with the
small-scale fading from the BS to users 119932120783 and 119932120784 respectively
1199511 and 1199512 are the additive white Gaussian noise with zero mean and variance
119925120782
Step 4 the BS transmit signal-to-noise ratio (SNR)
120646 = 119927119925120782
Step 5 Signal-to-Interference-plus-Noise-Ratio (SINR) for the two users 119932120783
decodes the signal of the weak user first then decodes its own signal after using
SIC 119932120784 is an untrusted user and tries to decode the near user message after
decoding its own message using SIC
11987811986811987311987721 =
(1minus119905)ȁℎ1ȁ2
119905ȁℎ1ȁ2+1120588ൗ and 1198781198681198731198771
1 = 119905120588ȁℎ1ȁ2
11987811986811987311987722 =
(1minus119905)ȁℎ2ȁ2
119905ȁℎ2ȁ2+1120588ൗ and 1198781198681198731198771
2 = 119905120588ȁℎ2ȁ2
119879119900119905119886119897119904119894119899119903 = ሼ11987811986811987311987721 1198781198681198731198771
1 11987811986811987311987722 1198781198681198731198771
2ሽ
where 119930119920119925119929119950119951
is the signal-to-interference-plus-noise-ratio (SINR)
of user 119950th decoded by 119932119951 for 119898 119899120598ሼ119894 2ሽ and ȁ119945119950ȁ2 is the
channels gain of 119932119950
Algorithm II
Partially observable Markov decision process
Step 1 Prediction of the maximum capacity of channel with respect to the data rate
119955119943 = 119877(119878119909119863)
S is denoted as states
Let D be the channel characteristics which are considering here as actions
Reward function R
Step 2 The agent receives an observation 119900120598120118which depends on the new state of
the environment 119930prime and on the just taken action 119941 with probability
119926(119952ȁ119956prime 119941)
Step 3 Reward earned at time t is expressed as
57
119903119891119905 = 119877(119878119909119863)119905
Step 4 reward function on belief states
119919 is the belief states over POMDP states
119919119943 is the belief state transition function
119955119943 = 119877(119867119909119863)
Step 5 The reward function is updated based on the belief MDP the agent only
cares about which action will yield the largest expected immediate reward ie the
maximum capacity channel
119861119891 ቀℎ 119889 ℎprimeቁ = 119875119903 (
119900120598120118
ℎprimeȁℎ 119889 119900) 119875119903(119900ȁ119889 ℎ) 119861119891
119875119903(ℎprimeȁℎ 119889 119900) = ቄ1119894119891119905ℎ119890119887119890119897119894119890119891119906119901119889119886119905119890119908119894119905ℎ119886119903119892119906119898119890119899119905119904ℎ 119889 119900119903119890119905119906119903119899119904ℎprime
0119900119905ℎ119890119903119908119894119904119890
119903119891(ℎ 119889) = σ ℎ(119904)119877(119904 119889)119904isin119878
34 SUMMARY
The NOMA-UAV communication framework has been proposed in this research
work and the Physical Layer security aspect has been focused on for optimization
The PLS performance metrics selected are SOP amp Pair OP in the proposed system
model The POMDP framework is general enough to model a variety of real-world
sequential decision-making problems Applications include robot navigation
problems machine maintenance and planning under uncertainty in general Here
we have adopted the User pairing POMDP algorithm for resource allocation in two
users amp multi-user NOMA-UAV communication networks The proposed study has
been evaluated using performance measures by varying distances of trusted amp
untrusted users from the base station as well as for varying SINR conditions The
simulation results and outcomes are discussed in a further chapter
58
CHAPTER 4
RESULT AND DISCUSSION
41 PERFORMANCE MEASURES OF SECURED NOMA-
UAV COMMUNICATION MODEL
Drones or UAV-based communication technology has been thoroughly studied and
adopted by the 3GPP standard UAV systems have been envisaged to form an
integral part of future wireless communication applications due to their dynamic
flexible and flying nature Due to their ability to reach higher altitudes they usually
have dominant LOS channels with the ground nodes This capability can be used to
provide confidentiality to the legitimate receivers against the eavesdroppers This
can be done by deploying UAVs to launch more effective jamming signal attacks
to terrestrial eavesdroppers The conventional cooperative jamming schemes make
an assumption that the locations of terrestrial jammers are fixed which might
compromise the secrecy of the system if the jammers are located far away from the
eavesdroppers and is also not practical as it makes an assumption of perfect CSI of
the jammer to eavesdropper channel
Here in the proposed scenario of the NOMA-UAV communication network two
key PHY layer security metrics SOP amp Pair Outage Probability have been jointly
optimized for a more effective power allocation factor for NOMA cellular
architecture The varying channel characteristics have been analyzed to achieve the
desired SOP with the constrained threshold minimum target secrecy rate for the
two-user scenario POMDP Algorithm iteratively provides the optimized SINR that
has been used to keep trusted users in pair with the untrusted user with minimum
achievable outage probability
The proposed NOMA-UAV System model has been simulated in MATLAB 2019b
version with mainly Communications System Toolbox Optimization Toolbox RF
Toolbox Signal Processing Toolbox Statistics and Machine Learning Toolbox
The simulation has been carried out for two-user pair to achieve desired secrecy
target rate and feasible pairing between trusted user amp untrusted user(eves-dropper)
59
The optimal-outage performance of minimized pair OP subjected to SOP constraint
has been solved by both dynamic programming optimization and POMDP
optimization approaches
The simulation of the proposed framework for the UAV-NOMA communication
network has been carried out and discussed in two parts two user models and a
multi-user model as below mentioned discussion The base station is deployed at
the center of a cell of radius 1000 m There are two users in the system under
consideration The channel between two nodes in the system suffers both the small-
scale fading and path loss effect Small-scale fading follows the exponential
distribution with the mean value 1 The noise signal of all channels has a Gaussian
distribution with 0 mean and variance 1 The path loss exponent α and the path loss
constant PLo are set to 2 and 01 respectively We assume a normalized bandwidth
of 1 Hz The SOP constraint threshold is assumed 01 and the target secrecy rate is
001 The power allocation coefficient is 015 and the BS transmitted SINR is
assumed 15dB for the proposed model As per the NOMA transmission scheme
SINR has been obtained for User 1 amp User 2 both for SIC decoding POMDP
algorithm optimally tunes the SINR value for User 1 amp User 2 that is considered to
select optimal power allocation coefficient for both trusted and untrusted users with
respective SOP of User1
42 Numerical results and Discussion
Table 41 Simulation Parameters
Parameters Values
Untrusted user Distance (d2) 200-1000 (300 700)
BS transmit signal-to-noise ratio (SNR) (120588) in dB 15
Sop constraint constant threshold (β) 01
Power allocation factor (t) 015
Trusted User distance (d1) 2-
60
Cell Radius (rd) 1000 meters
Path loss exponent (α) 2
Path loss constant (PLo) 01
Normalized bandwidth in Hz 1
Target secrecy rate (Rs) 001
No of Bits 100
Pair Outage Probability (P0) 05250
SINR 5319 15305 5162
10247
421 Feasible amp Infeasible pairing of trusted amp Untrusted users
In this section the CSI value broadcasted by Base Station is assumed 15 dB initially
and for varying channel conditions various SINR values of 120646 = minus20 minus10 20 dB
is described with target secrecy rate 0005 and 001 for power allocation coefficient
015 and User 1 distance at 200m is shown in the Figure 41 below
Figure 41 Impact on Sop with increase distance between BS and user U2
61
Varying target secrecy rate threshold from 0005 to 001 the obtained result in
Figure 42 revealed that the 1199321 is a gradually reducing function for the distance of
untrusted user d2 that implies that the increasing value of d2 leads to the
improvement of the SOP of 1198801
Figure42 Impact on Sop with increase distance between BS and user U2
Since the offered constant threshold 120656 in SOP limit1199322 which should be located at
a larger space when compared with a value of threshold to attain the SOP of 1199321
apart from that it is expected the high target secrecy rate maximizes the SOP of 1199321
Here in below figure the power allocation coefficient has been varied from 0 to 1
with threshold value of t and the desired t_sop for feasible pairing
Figure 43 Feasible pairing t Vs pair OP
62
Pair OP in case of rising 1199322 untrusted user in d2 for different BS transfer the SNR
where t= 015 and d1=200mThe infeasible pairing of SOP (1199321) and the OP pair
by the enhanced allocation of the power (t) d1 (200m) d2 (300m) 120646 = 15 dB and
120656 = 0
Figure 44 shows the identical plotting of data by adjusting the unauthenticated
level of the user through converting it to a BS closer distance (d2=300m) Accuracy
is compared and checked with the full spectrum of numerical simulations The
result has shown that the effectiveness is based on a comparative study of the two
consumers of the BS
Figure 44 Infeasible pairing t Vs pair OP
422 The Secrecy Outage Probability amp Pair Outage Probability
Feasible paring in the SOP of pair OP and 1199321 with the improved power allocation
factor t in which d2=700m d1=200m 120646 = 15119889119861 and The result described that
the OP and SOP of the user 1199321 with increased for two various distances of the 1199322
untrusted user The simulation result approves the convex nature 120656 = 0 1of the OP
and the SOP is sequentially decreased depending on t Generally when it enhances
the power owed to the weak user text reduces that develop the ability of 1198802 for
discerning the superior positioned signals therefore enhancing the SOP of 1198801
63
Figure 45 Secrecy outage probability
Figure 46 Pair outage probability
423 SNR versus Strictly Positive Secrecy Rate
Figure 47 proved that the potential for confidentiality is superior to the existing
techniques The proposed application for pre-coding improves the efficiency of the
device The transmission power of the system is the power needed for the
transmission of particular data
64
Figure 47 SNR versus Strictly positive secrecy rate
If there is a growth in the number of users there is a risk of inference in the
transmission of data and thus the reliability of the data rate may be affected Based
on these cases the efficiency of the antenna power to be withheld and occupy the
data determined
424 Power radiated by per MMBs antenna
In the case of multi-users scenario when there are more than two users then the
allocation of an optimized resource block to all users is the key parameter to achieve
desired outage efficiency because strong users require higher SNR for higher data
rates and weak users are allocated minimum threshold SNR for lower data rate
requirements to maintain suitable pairing OP and SOP balance
Figure 48 Power radiated by per MMBs antenna
65
So the POMDP policy optimization has shown better performance over the
dynamic programming approach particularly when more users are active (a greater
number of antennas as in Figure 48 the overall radiated power per BS antenna in
downlink has been considerably reduced
43 CONCLUSION AND SCOPE OF FUTURE WORK
431 Conclusion
Starting with LTE (4G) OFDMA has replaced WCDMA with mobile cellular
communications and will also be used during advanced 5G while Non-Orthogonal
Multiple Access (NOMA) has recently been recognized as a groundbreaking PHY
technology in UAV communication NOMA scheme is used in place to increase the
effective use of small resources such as in UAV communication where the data rate
is very low and critical decision making is of utmost importance
The critical need for UAV communication is a secure PHY layer for mission-
critical applications and as NOMA doesnrsquot promise high security the proposed
research work has been carried out to enhance the insecurities of NOMA-UAV
communication In this proposed research work the probabilities of confidential
outage (SOP) and OP were investigated in the two-user NOMA system Here BS is
required to pair a trusted or permissible user with other untrusted users due to the
unequal distribution of untrusted and trusted users in the cell The SIC is then
applied to the receiver side intended for decoding the message signals The Pair OP
of both users has been analyzed for varying Target Secrecy Rate (Rs) of the trusted
user U1 which provides constraint threshold of the SOP of U1
By varying the distance of Untrusted users from BS the optimal distance and power
allocation factor for the feasible pairing of trusted and untrusted users without
compromising the secrecy outage probability of U1 has been achieved in simulation
results
POMDP has provided the optimal power allocation as a resource allocation
algorithm in the dynamically changing environment of two user NOMA cases
where the distance between BS and untrusted user varies significantly The
performance of secure NOMA-UAV is affected critically by (SOP of User 1) which
66
should be optimally selected to maintain the proposed Pair OP between both users
and the simulation results have supported this optimal outage performance Thus
NOMA-UAV architecture has the potential of providing a secure PHY layer for
mission-critical applications by opting for suitable decision-making resource
algorithm POMDP
431 Scope of Future Work
Furthermore the multiuser scenario with the increased number of Untrusted users
can be analytically verified and simulated in the same direction for NOMA-UAV
communication to improve transmission security and reliability In addition more
adaptive and efficient Resource allocation algorithms for NOMA-UAV networks
with secured performance in real-time applications should be investigated
1
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11
PUBLICATIONS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495449|P a g e
Migration from 4g LTE to Advanced PHY Techniques for
Unmanned Aerial Vehicle (UAV) Communication
Pankaj Patel PHD StudentGujarat Technological UniversityGujarat India
ABSTRACT
UAV (unmanned aerial vehicles) with their high mobility and low cost have found a wide range of applications
during the past few decades Historically UAVs have been primarily used in the military mainly deployed in
hostile territory to reduce pilot losses With continuous cost reduction and device miniaturization small UAVs
are now more easily accessible to the public hence numerous new applications in the civilian and commercial
domains have emerged For the sake of boosting resilience against faults natural disasters and unexpected
traffic the Unmanned Aerial Vehicle (UAV) assisted wireless communication systems can provide a unique
opportunity to cater for such demands in a timely fashion without relying on the overly-engineered cellular
network However for UAV-assisted communication issues of capacity coverage and energy efficiency are
considered of paramount importance Starting with LTE (4G) Orthogonal Frequency Division Multiple Access
(OFDMA) has replaced WCDMA for cellular mobile communications and it will also be employed in advanced
5G yet Non-orthogonal multiple access (NOMA) has been recently recognized as a promising PHY technique
to significantly improve the spectral efficiency of mobile communication networks In this paper we provide an
overview of UAV-aided wireless communications by introducing the basic networking architecture
highlighting the key design considerations as well as the new opportunities to be exploited
Keywords LTE (4G) Non-orthogonal multiple access (NOMA) Unmanned Aerial Vehicle (UAV) Wireless
communication
----------------------------------------------------------------------------------------------------------------------------- ---------
Date Of Submission 26-04-2019 Date Of Acceptance 06-05-2019
----------------------------------------------------------------------------------------------------------------------------- ----------
I INTRODUCTION The use of unmanned aerial vehicles
(UAVs) will grow rapidly in the next decade These
remotely piloted or preprogrammed aircraft are
envisioned for applications in numerous civil
settings including industrial monitoring scientific
data gathering agriculture public safety and search
and rescue Many other applications - presently
unforeseen - will inevitably also arise These
vehicles also known as the unfortunate misnomer of
drones must be integrated into the national
airspace system and into the airspace worldwide A
natural concern in the use of UAV is safety and this
has direct implications for the control and non-
payload communication systems that must be used
to operate it efficiently Similarly navigation and
surveillance functions must be made more reliable
and more accurate Because of these factors many
UAV research development testing and
standardization efforts are underway by
governments industries and academia Despite the
fact that piloted civil aircraft have been flying safely
for decades UAV presents distinct new challenges
in the form of different flight profiles eg low-
elevation flights and more high-dynamic maneuvers
wider required bandwidths eg for video and
different ground site characteristics such as locations
in cluttered areas and lower elevation antennas
In this paper first the evolution of radio
technologies considered in UAV wireless
communication is reviewed in literature survey and
the significant work in the area is highlighted along
with the newest challenges The reminder of this
paper is organized as follows
The promising technology NOMA and its
variants are discussed in section three In Section
four the system model and assumptions are
presented and in section five the comparative
analysis of NOMA with existing popular technology
OFDMA (OMA) is given with simulation
persormance analysis At last the work is concluded
in section five
II LITERATURE SURVEY Drones variously known as unmanned
aerial vehicles (UAVs) unmanned aerial systems
(UAS) or remotely piloted aircraft system (RPAS)
are used in several parts of the world for surveying
and aerial mapping disaster management work
monitoring crop production and infrastructure
activities besides commercial photography and
courier delivery The viability of UAV as a
multipurpose research vehiclehas driven great
RESEARCH ARTICLE OPEN ACCESS
Pankaj PatelJournal of Engineering Research and Application wwwijeracom
ISSN 2248-9622 Vol 9Issue 4 (Series -IV) April 2019 pp 49-54
wwwijeracom DOI 1097909622- 090404495450|P a g e
interest since recent decades[1] The
basictechnology building blocks responsible for the
current advancesinclude airframes propulsion
systems payloadssafety or protection systems
launch and recovery dataprocessor ground control
station navigation and guidanceand autonomous
flight controllers The following briefsurvey is
focused on the area of navigation guidance
andcontrol of UAVs Various control design for
UAVs has beenproposed ranging from linear to
nonlinear synthesis timeinvariant to parameter
varying and conventional PID tointelligent control
approaches The developed controllershave been
implemented for different aerial platforms
airship(blimp) fixed-wing UAV small scale
helicopteruad-rotors and MAV Wireless
communication systems that include unmanned
aerial vehicles promise to provide cost-effective
wireless connectivity for devices without
infrastructure coverage Compared to terrestrial
communications or those based on high-altitude
platforms on-demand wireless systems with low-
altitude UAVs are in general faster to deploy more
flexibly reconfigured and likely to have better
communication channels due to the presence of
short-range line-of-sight links However the
utilization of highly mobile and energy-constrained
UAVs for wireless communications also introduces
many new challenges In India for the regulation
and safety purpose in commercial and survilence
applications the policy guideliens also introduced
as below
Table 1UAV communication Policy Guidelines for
commercial and surveillance purpose
III MIGRATION FROM 4G LTE TO 5G The fruitful deployment of UAV based
communicationsystems for 4G and beyond future
wireless networks is highlyinvolved in finding joint
solutions to challenge of ubiquitousconnectivity with
both a multitude of devices in a spectralefficient way
as well as with energy-efficient transmissionand
operation of the UAV-BS for maximized and
armonizedcoverage and capacity [2][3] It should be
noted that suitableenergy efficiency for the UAV-
assisted ommunication systemachieves paramount
importance in the overall performance ofthe system
Efficient energy consumption results in
enhancedairtime for the communication system
improving bitsJoulesfor a given energy level
Furthermore coverage and capacityof an aerial cell
are attributed to many factors such as
thetransmission power antenna gains UAV
altitude deploymentenvironment and prominently
radio access technology [4]
4G is the fourth generation of broadband
cellular network technology succeeding 3G and
besides the popular techniques in 3G4G ie
TDMAWCDMAOFDMA a new radio access
technology NOMA is also developed by researchers
to be used in communication networks due to its
capability in increasing the system capacity
Recently non-orthogonality based system designs
are developed to be used in communication
networks and have gained significant attention of
researchers Hence multiple access (MA) techniques
can now be fundamentally categorized as orthogonal
multiple access (OMA) and non-orthogonal
multiple access (NOMA) In OMA each user can
exploit orthogonalcommunication resources either
within a specific time slot frequency band or code in
order to avoid multiple access interference The
previous generations of networks have employed
OMA schemes such as frequency division multiple
access (FDMA) of first generation (1G)time
division multiple access (TDMA) of 2G code
division multiple access (CDMA) of 3G and
orthogonal frequency division multiple access
(OFDMA) of 4G
In NOMA multiple userscan utilize non-
orthogonal resources concurrently by yielding a high
spectral efficiency while allowing some degree of
multiple access interference at receivers Recently
NOMA reputations have climbedsharply as a
fundamental solution to the challenges
encompassingthe next generation wireless networks
[5][6]NOMA has been proved to exhibit improved
spectral efficiencybalanced and air access as
compared to OMAtechnologies[6] with the ability
to cater for multipledevices in the same frequency
time or code resource thusproviding efficient access
to massive connected devices Furthermore NOMA
is also instrumental in reducingthe interference by
employing orthogonal resources as inOrthogonal
Frequency Division Multiple Access
(OFDMA)[7][17] or by sharing a single beam
between multiple users forintra-cluster access and
using NOMA for inter-cluster access[18]Current
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studies have focused on provisioning Air to
Ground(A2G) communication services mainly
through placement op- timization under various
viewpoints in literature The performance of UAV
based communication systems hasalso been
addressed for the underlaid Device to Device(D2D)
deployment scenario This work assumed
interferenceraised by D2D network nodes without
considering the presenceof terrestrial BS
Additionally there have been a fewstudies
discussing the performance of NOMA for UAV
basedcommunication system[8] A NOMA enabled
fixedwingUAV deployment was proposed in [8] to
support coveragefor ground users situated outside
BS offloaded location
In general NOMA schemes can be
classified into two types power-domain
multiplexing andcode-domain multiplexing In
power-domain multiplexing different users are
allocated[7][8][9][6][5][1][10] differentpower
coefficients according to their channel conditions in
order to achieve a high systemperformance In
particular multiple usersrsquo information signals are
superimposed at the transmitterside At the receiver
side successive interference cancellation (SIC) is
applied for decoding thesignals one by one until the
desired userrsquos signal is obtained providing a good
trade-offbetween the throughput of the system and
the user fairness In code-domain multiplexing
different users are allocated different codes and
multiplexed over the same time-frequencyresources
such as multi-user shared access (MUSA) sparse
code multiple access (SCMA) and low-density
spreading (LDS) In addition to power-domain
multiplexing and codedomain multiplexing there are
other NOMA schemes such as pattern division
multiple access(PDMA) and bit division
multiplexing (BDM) Although code-domain
multiplexinghas a potential to enhance spectral
efficiency it requires a high transmission bandwidth
andis not easily applicable to the current systems
On the other hand power-domain multiplexinghas a
simple implementation as considerable changes are
not required on the existing networksAlso it does
not require additional bandwidth in order to improve
spectral efficiency Inthis paper the prime focusis on
the power-domain NOMAAlthough OMA
techniques can achieve a good system performance
even with simple receiversbecause of no mutual
interference among users in an ideal setting they
still do not have theability to address the emerging
challenges due to the increasing demands in future
networks andbeyond
The superiority of NOMA over OMA can
besummarized as follows
_ Spectral efficiency and throughput In OMA such
as in OFDMA a specific frequencyresource is
assigned to each user even it experiences a good or
bad channel conditionthus the overall system suffers
from low spectral efficiency and throughput In
contrary inNOMA the same frequency resource is
assigned to multiple mobile users with good and
bad channel conditions at the same time Hence the
resource assigned for the weak user isalso used by
the strong user and the interference can be mitigated
through SIC processesat usersrsquo receivers Therefore
the probability of having improved spectral
efficiency and ahigh throughput will be considerably
increased
_ User fairness low latency and massive
connectivity In OMA for example in OFDMAwith
scheduling the user with a good channel condition
has a higher priority to be servedwhile the user with
a bad channel condition has to wait to access which
leads to a fairnessproblem and high latency This
approach cannot support massive connectivity
HoweverNOMA can serve multiple users with
different channel conditions simultaneously
thereforeit can provide improved user fairness lower
latency and higher massive connectivity
_ Compatibility NOMA is also compatible
with the current and future communication
systemssince it does not require significant
modifications on the existing architecture For
exampleNOMA has been included in third
generation partnership project long-term
evolutionadvanced (3GPP LTE Release 13)
Figure 1Pictorial comparison of NOMA Vs OMA
Although NOMA has many features that
may support next generationsit has some limitations
that should be addressed in order to exploit its full
advantage set Thoselimitations can be pointed out
as follows In NOMA since each user requires to
decode thesignals of some users before decoding its
own signal the receiver computational
complexitywill be increased when compared to
OMA leading to a longer delay Moreover
informationof channel gains of all users should be
fed back to the base station (BS) but this results in
asignificant channel state information (CSI)
feedback overhead Furthermore if any errors
occurduring SIC processes at any user then the error
probability of successive decoding will beincreased
As a result the number of users should be reduced to
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avoid such error propagationAnother reason for
restricting the number of users is that considerable
channel gain differencesamong users with different
channel conditions are needed to have a better
network performance
IV NOMA UPLINK AND DOWNLINK
SCENERIO SIMULATION ANALYSIS In this section an overview of NOMA in
downlink and uplink networks is introduced
throughsignal-to-interference-and-noise ratio (SINR)
and sum rate analyses Then high signal-to-
noiseratio (SNR) analysis has been conducted in
order to compare the performances of OMA
andNOMA techniques[10]
A Downlink NOMA Network
At the transmitter side of downlink NOMA
network as shown in Fig 2 the BS transmits
thecombined signal which is a superposition of the
desired signals of multiple users with different
allocated power coefficients to all mobile users At
the receiver of each user SIC process isassumed to
be performed successively until userrsquos signal is
recovered Power coefficients ofusers are allocated
according to their channel conditions in an inversely
proportional mannerThe user with a bad channel
condition is allocated higher transmission power
than the one which has a good channel condition
Thus since the user with the highest transmission
power considers the signals of other users as noise
and recovers its signal immediately without
performing anySIC process However other users
need to perform SIC processes In SIC each userrsquos
receiverfirst detects the signals that are stronger than
its own desired signal Next those signals
aresubtracted from the received signal and this
process continues until the related userrsquos own signal
is determined Finally each user decodes its own
signal by treating other users with lower
powercoefficients as noise The transmitted signal at
the BS can be written as
s = aiPsxi
L
i=1
where xi is the information of user i (Ui)
with unit energy Ps is the transmission power atthe
BS and ai is the power coefficient allocated for user
i subjected to ai = 1Li=1 and a1gea2gehellip geaL since
without loss of generality the channel gains are
assumed to be ordered as h1 2 le h2 2 le⋯ hL 2 where hL is the channel coefficient of Lth
user based on NOMAconcept The received signal
at lth user can be expressed as follows
y1 = hls + nl = hl aiPsxi + nlL
i=1
where nlis zero mean complex additive Gaussian
noise with a variance of σ2
(1) SINR analysis By using (2) the instantaneous
SINR of the lth user to detect the jth user jle l
with jne L can be written as
SINRl = alγ hl 2
γ hl 2 aiLi=l+1 + 1
Where γ = Psσ2 denotes the SNR
(2) Sum rate analysis After finding the SINR
expressions of downlink NOMA the sumrate
analysis can easily be done The downlink
NOMA achievable data rate of lth user can
beexpressed as
RlNOMA-d
= log2 1 + SINRl = log2(1 +alγhl2γhl2 i=l+1Lai+1
B Uplink NOMA Network
In uplink NOMA network as depicted in
Fig 3 each mobile user transmits its signal to the
BS At the BS SIC iterations are carried out in order
to detect the signals of mobile users By assuming
that downlink and uplink channels are reciprocal and
the BS transmits power allocation coefficients to
mobile users the received signal at the BS for
synchronous uplink NOMA can be expressed as
r = hi aiPxi + n
L
i=1
where hi is the channel coefficient of the ith
user Pxi is the maximum transmission power
assumed to be common for all users and n is zero
mean complex additive Gaussian noise with a
variance of σ2
Figure 2Downlink NOMA network
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Figure 3 Uplink NOMA network
1) SINR analysis The BS decodes the signals of
users orderly according to power coefficientsof
users and then the SINR for lth user l ne 1 can
be given by
SINRl =alγ hl 2
γ ai hi 2 + 1lminus1i=1
where γ =P
σ2
2) Sum rate analysis The sum rate of uplink
NOMA when γ minus infincan be written as
Rsum NOMA-u asymp log2(γ hl 2L
l=1
C Comparing NOMA and OMA
The achievable data rate of the lth user of OMA for
both uplink and downlink can be expressed
RsumOMA = αl log2(1 +
βlγ hl 2
αl)L
l=1
For the sake of simplicity sum rates of
uplink NOMA and OMA can be compared for
twousers Then using both the sum rate of uplink
NOMA and OMA at high SNR can beexpressed
respectively as
RsumNOMAasymp log2 γ h1 2 + γ h2 2
Here we notice ROMA
sumle RNOMA
sum
Fig shows that NOMA outperforms OMA in terms
of sum rate in both downlink and uplinkof two
user networks
V SIMULATION RESULTS
The Comparative analysis of modelling
Downlink and Uplink NOMA in comparison with
OMA is simulated and findings are presented that
shows superiority of NOMA over OMA with better
spectral efficiency for simulation parameters taken
as power allocation coefficients a1=06 a2=04 and
channel responses h1 2
=0 DB h22=20 DB
parameters
Figure 4NOMA UPLINK
Figure 5 NOMA DOWNLINK
VI CONCLUSION This paper investigated an account of
NOMArsquos applicability for UAV-assisted
communication systems NOMA schemes are
proposed to improve the efficient usage of limited
network sources OMA based approaches that use
time frequency or code domain in an orthogonal
manner cannot effectively utilize radio resources
limiting the number of users that can be served
simultaneously In order to overcome such
drawbacks and to increase the multiple access
efficiency NOMA technique has been recently
proposed Accordingly users are separated in the
power domain Such a power domain based multiple
access scheme provides effective throughput
improvements depending on the channel conditions
The crucial need of UAV communication of
optimum utilization of available licensed spectrum
bandwidth is considered here and simulation results
taken presented that NOMA performs better than
OMA while fulfilling individual user-rate constraint
for both users The research work can be further
carried out investigating joint power and phase
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allocation of UAV nodes deployment for efficient
operations
REFERENCES [1] S M I C Y L M I Muhammad Farhan Sohail
Non-Orthogonal Multiple Access for Unmanned
Aerial Vehicle Assisted Communication in IEEE
access 2018
[2] M Mozaffari Drone small cells in the clouds
Design deployment and performance analysis in
IEEE Global Communications Conference 2015
[3] R Z a T J L Y Zeng Wireless
communications with unmanned aerial vehicles
opportunities and challenges in IEEE
communication magazine 2016
[4] I B-Y a H Yanikomeroglu The new frontier in
ran heterogeneity Multi-tier drone-cells IEEE
Communications Magazine pp 48-55 2016
[5] P K S a D I Kim Uav-enabled downlink
wireless system with NOMA access in IEEE
Globecom Workshops Dec 2017
[6] P Xu and K Cumanan Optimal power allocation
scheme for nonorthogonal multiple access with
fairness in IEEE Journal on Selected Areas in
Communications oct 2017
[7] E H a D I K S Ali Non-orthogonal multiple
access (noma) for downlink multiuser mimo
systems User clustering beamforming and power
allocation in IEEE Access 2017
[8] W S M B a M D M Mozaffari Unmanned
aerial vehicle with underlaid device-to-device
communications Performance tradeoffs in IEEE
Transactions on Wireless Communications June
2016
[9] Z D X D a R Z Z Chen An optimization
perspective of the superiority of noma compared to
conventional oma in IEEE Transactions on
Signal Processing Oct 2017
[10] M T Mahmoud Aldababsa1 and S G G K 2 A
Tutorial on Non-Orthogonal Multiple Access
2017
[11] X L Z J W a K J R L Zhu Han Delay
Sensitive Scheduling Schemes for Heterogeneous
QoS over Wireless Networks IEEE
TRANSACTIONS ON WIRELESS
COMMUNICATIONS VOL 6 NO 2
FEBRUARY 2007 vol 6 no 2 2007
[12] Z J W a K J R L Z Han A resource
allocation framework with credit system and user
autonomy over heterogeneous wireless networks
in IEEE Global Telecommunications Conference
2003
[13] N B S a P S S Chen Heterogeneous delay
tolerant task scheduling and energy management in
the smart grid with renewable energy IEEE
Journal of Selected Areas in Communications vol
31 no 07 pp 1258-1267 july 2013
[14] H L Z C a Z H Y Hu Scheduling strategy for
multimedia IEEE Transactions on Vehicular
Technology July 2016
[15] P F a K B L Y Dong High-speed railway
wireless communications efficiency vs fairness
IEEE Transactions on Vehicular Technology vol
63 no 2 pp 925-930 march 2014
[16] T R a Z H Z Chang Queueing game for
spectrum access in cognitive radio networks
IEEE Communications Letters vol 19 no 11 pp
2017-2020 June 2015
[17] Z C L T R a Z H F I Yun Hu Service
Provisioning and User Association for
Heterogeneous Wireless Railway Networks IEEE
Transactions on Communications 2017
[18] H S W Tianti Chen Optimal Scheduling for
Wireless On-Demand Data Packet Delivery to
High-Speed Trains IEEE Transactions on
Vehicular Technology vol 64 no 9 pp 4101 -
4112 september 2015
Pankaj Patel Migration from 4g LTE to Advanced PHY Techniques for Unmanned Aerial
Vehicle Communication International Journal of Engineering Research and Applications
(IJERA) Vol 09 No04 2019 pp 49-54
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Improving Of Physical Layer Insecurity Of The
Non Orthogonal Multiple Access System
Pankaj M Patel Prof Dr Chetan B Bhatt
Abstract The key aspect of the NOMA (power domain non orthogonal) is the user possibility for decoding the messages belonging to another pair users
on similar resources The method interprets a security threat especially in the case where the base station serves the users with various security
clearance or untrusted users The main aspect of NOMA is to serve the multiple users upon the similar radio resources at the minimal inter user
interference expense The system not only permits the serving of particular users with high efficient bandwidth but also permits the scheduling more type
of users than the timely available users In this study we investigated the secrecy outage probability (SOP) and OP in the both two user and multi user
NOMA system where the BS is supposed to pair a trusted or legitimate user with other untrusted users because of the un even distribution of the
untrusted and trusted users in the cell SIC the successive interference cancellation was then implemented at the receiver side for decoding the
message signals With the application of NOMA concept the study investigated the pair outage behavior under the SOP constraints on the trusted users
In specific the SOP and OP of the concerned U1 were obtained in the closed type of expressions The study also provided the understanding the
possibility of obtaining an optimal outage efficiency for pairing under the SOP constraints With certain numerical simulations the study verified the
effectiveness of the analytical derivations with respect to various scenarios
Index Terms NOMA Secrecy outage Probability Successive Interference Cancellation bandwidth channel state information etc
mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash mdashmdashmdashmdashmdashmdashmdashmdashmdashmdash
1 INTRODUCTION The physical layer security and non-orthogonal multiple
access was regarded as the encouraging techniques for the
processing of wireless communication network systems Today
the combination of the two significant communication methods
was studied to guarantee a spectral efficient and secure
wireless transmission Most of the prevailing works
predominantly concentrated on the optimization and efficiency
of the PLS in the existence of untrusted relay nodes and
external eavesdroppers(Arafa et al 2019a)But there occurs a
gap in the theoretical studies to describe the ease of obtaining
the enhanced efficiency in the existence of untrusted users
Recently the network traffic amount have greatly enhanced
particularly with the updated growth in IoT applications in
future To rectify the huge traffic demand upcoming wireless
networks must deliver a best spectral effectiveness and large
connectivity (Sun et al 2018) NOMA is regarded as the best
technology in which various NOMA technique exhibit similar
concept of providing several users at the similar frequency and
time The famous NOMA types are code domain and power
domain that provided enhanced efficiency when compared
with the existing techniques The paper adopted the power
domain on the basis of super position coding (transmitter side)
at the SIC (receiver side) Hence the users could possess the
key for the messages of other users and thereby utilize SIC for
removing the interference (Cao et al 2019) (Zhao et al
2018) Hence various NOMA methods was proposed for
allowing the adjacent users to perform as a relay for improving
the efficiency of the weak users through the resending of
decoded data in a next time slot The weak user could utilize
the MRC technique to integrate the information achieved in
different time slots In addition obtaining a secured
communication is a crucial problem over the vulnerable
wireless networks to security threats mainly because of the
broadcasted transmission nature
The study investigated the secrecy performance and outage
with the untrusted user(Furqan et al 2019) The main aspect
of the study is to analyze the feasibility of achieving the OP of
the pair under a trusted user Because of the decoding facility
and spectrum sharing of SIC the untrusted user could perform
as a eavesdropper
Figure 1 Representation of Base station
Figure 1 depicts the representation of base station The main
aim of the proposed system defined as
bull To investigate the outage probability of the proposed
system
bull To investigate the SOP of the proposed system
bull To derive the accurate expression of the outage
probability for all kind of scenarios and closed form of
expressions for few special cases and verifying them
numerically for yielding a better outage efficiency
2 RELATED WORKS This section describes the different existing techniques and
methods related as our proposed system (Cao et al
2019)suggested two kinds of relay selection process denoted
as AF (amplify and forward) and DF (decode and forward) on
the basis of AORS and DORS for achieving secure and
reliable NOMA systems under the untrusted users The study
derived the accurate and asymptotic closed form of the SOP
expressions and the PSCP obtained by the two methods and
investigated the optimized feature of the two methods The
____________________________________
bull PANKAJ M PATEL is currently pursuing PHD program in Electronics
amp Communication in Gujarat Technological University E-mail
pankajmphd24gmailcom
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complete analysis and the simulation results represented that
both the AORS and DORS characteristically outperformed the
benchmark system apart from obtaining the similar SOP and
the required PSCP at very high Signal to noise ratio (Zhang et
al 2018)Investigated the power allocation and joint subcarrier
issue for NOMA ndashAF two-way relay networks with restrictions
The study focused to optimize the obtainable secrecy
efficiency by designing jointly the SC task power allocation
and user pair scheduling The paper suggested a SCAS-1
technique by assuming the appropriate information about the
channel state information in the relay station followed by the
formulation of SCAS-2The secured power allocation issue is
structured as a convex programming issue and then resolved
by in-depth point techniques The results of simulation
explained that the efficiency of the suggested SSPA algorithms
with and without CJ respectively (Arafa et al
2019b)Considered a downlink system where the base station
is connecting with two appropriate users in two various
scenarios in the unsecured environments which are the
presence of the eavesdropper and untrusted relay
communication In the first process several trusted
cooperative relays is engaged for assisting with the base
station transmission and protect the corresponding signals
from the eavesdropper Several relay methods are framed and
investigated for the following process which are forward and
decode cooperative jamming and AFFor all the technique
secured beam forming signals were formulated at the relays
for maximizing the obtainable secret rate areas For the next
process with untrusted relay the obtained secrecy rate areas
obtained for two various relay schemes which are AF and CF
under two various operation modes In the first process the
prescribed users will receive the signals from the untrusted
relay and the base station for decoding the messages The
study depicted that the efficient relay scheme is highly
dependent on the parameters of the system especially the
nodal distance and the secrecy rate area (Sun et al
2018)Studied the algorithm for resource allocation for MISO
systems where the full duplex BS serve several half duplex
downlink and uplink users on the similar subcarrier The
allocation of the resource have been optimized for maximizing
the weight system output whereas the leakage of information
was restricted and an artificial noise was induced for granting
secured communication with respect to potential
eavesdroppers The study formulated a novel non-convex
optimization issue by considering the imperfect CSI of the
channels and requirements of QoS of legitimate users The
simulation results stated the efficiency of the optimal algorithm
was related to the suboptimal algorithm Apart from that the
suggested MISO NOMA technique not only guarantee uplink
and downlink communication purpose for security but delivers
a characteristic rate of system secrecy when compared with
the conventional MISO and other two baseline methods
(Dang et al 2017)Analysed the outage efficiency of various
multicarrier relay selection techniques for 2 hop OFDM system
in Poisson relay fields The study concentrated on DF relay
systems with more selection schemes The accurate
expressions for the OP are provided in integrals generally
Apart from that asymptomatic derivatives for OP in the SNR
region in the fixed circle area are predicted for both relay
selection techniques in closed forms Consequently several
significant factors that are linked to the cooperative network
were examined comprising OP ratio of two selection
techniques diversity and subcarrier optimization output In
conclusion a structure to analyze the OP of OFDM with
spatially random relay have been constructed that could be
easily altered for analyzing same case with various forwarding
protocols channel conditions and location distributors (Dang
et al 2018)Proposed a full duplex OFDM ndashD2D system in two
hop network where DF relays help the transmission from DUE
transmitter to DUE receiver The study also investigated the
OP issue by integrating the transmit power within the DUE
relays and transmitter and to deliver a suboptimal solution that
can improve the outage performance The investigations are
validated by Monte Carlo simulations These results described
could furnish an insight into full duplex OFDM system and
guides for the application in the next generation network
(Kokshoorn et al 2016) suggested a robust channel algorithm
for mmWave systems on the basis of novel overlapped pattern
design With the use of finite measurements the study
depicted that this decreased measurements was found ENR of
25 dB to obtain the similar PEEFor the appropriate channel
with quickly altering channel information the price might be
acceptable for improving the speed of estimation The study
also proposed a robust channel estimation algorithm where
the additional calculations are carried out when expecting
more estimation error The study depicted that the channel
could be measured more effectively resulting in noteworthy
gains upto 6 dB when comparing with the existing algorithm
(Ali et al 2016) described the variations in the principles of
downlink and uplink NOMA transmissions in a wireless
system The study formulated a maximization issue in a cell
like the user clustering and power allocations Because of the
integral nature of the formulated programming issue the study
solved the issue in to steps which are grouping of users into
clusters and then to optimize the corresponding power
allocations The study proposed a sub optimal scheme that
exploited the gain variations in NOMA groups and clusters into
multiple and single clusters for enhancing the sum-throughput
The results compared the efficiency of OMA and NOMA in
different network scenarios (Lv et al 2017) investigated a
MCR-NOMA where the multicast user functions as relays to
enhance the efficiency of both secondary and primary
networks On the basis of the available CSI three various
secondary user schedule techniques for processing MCR-
NOMA were depicted For evaluating the system efficiency the
study derived the closed form of expressions of OP and order
of diversity for both the networks It has been described that
more spatial temporal diversity could be obtained by using the
CSI for scheduling of the secondary user (Liu et al 2016)
considered a MIMO ndashNOMA scenario for investigating a
dynamic clustering issue in an logical perspective To resolve
the problem of optimization issue three algorithms named top
down A and B bottom up were suggested for realizing various
complexity tradeoff and worst user throughput The study
noted that the top down B algorithm could obtain a better
tradeoff between throughput and complexity amongst the
applied procedures (Fianu and Davis 2018) investigated
three various rules of allocation and demonstrated the optimal
policy as an available inventory function The study also
provided the country level estimation of requirements that are
not met and the determination of the probability distribution
linked with the total undeserved counties The study have
been done for depicting the policy of allocation with respect to
effectiveness and equity (Hou et al 2018) studied the socio
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graphical impact on the mobile video services and thereby
suggested a CTMDP on the basis of resource allocation
technique by considering social graphs as the constraints
With the use of relative value an optimized policy could be
achieved that aimed at increasing the reward regarding the
average system The simulation depicted that the suggested
CTMDP obtained an increased efficiency against the state of
art methods
3 PROPOSED WORK
Fig 2 Proposed flow depicting the overall mechanism
The proposed(Interference mitigation using POMDP) overall flow
is depicted in the figure 2 After setting up of the base station the
distance between the base station and the user was determined
and if the distance is less than 200 meters it is decided as trusted
users and if it is greater than 200 m it is defined as untrusted
users In case of untrusted users the channel state information is
subjected to POMDP (Partially observable Markov Decision
Process) followed by resource allocation The performance
analysis have been done after the system The work considered
a NOMA oriented cellular setup provided with a base station at
the centre and two users as shown in the figure 2 The adjacent
(near) user possess high level of security clearance that is
required for securing with physical layer from the low
securityuntrusted clearance user (U2) that is located at a faraway
distance from the base station P is defined as the maximum
transmit power level (base station)In this paper it is assumed that
all the network nodes are installed with single antenna and further
all the channels are considered to be identical independently
quasi static with Rayleigh distribution with respect to distribution
119862119873(0 120575 frasl
120596 frasl
) In which 120575 is the distance in-between the BS
and nodes 119880 Here path-loss exponent and path-loss constant is
represented as 120572 and 120596 In addition it is assumed that base
station predicted the user location so that a better CSI is
obtainable at base station that is involved in pairing the users
The base station transmits the superimposed mixture
119909 = radic119905 119904 + radic1 minus 119905 119904
In which 119904 119904 are the unit power signals received by users 119880 and
119880 respectively 119905 is the power
allocation coefficient for the adjacent user
119903 = ℎ 119909 radic119875 + 119899
119903 = ℎ 119909 radic119875 + 119899
where ℎ ℎ - the channel gain linked with the
small-scale fading from the base station to users 119880 and 119880
respectively 119899 and 119899 are the extra white Gaussian noise with
variance and zero mean 1198730 and it is assumed that 120588 = 1198751198730 is
the BS convey signal-to-noise ratio (SNR) In NOMA technique
farther user that possess more power
could decode its own signal by considering the adjacent signal as
a noise without decoding the adjacent user message In the
preceding equation it is assumed that U1 first decode the weak
signal followed by decoding its own signal with SICU2 which is
the untrusted user attempted to decode the near user message
after the decoding of the adjacent user messages after the
process of decoding its own message with SICHence the
following equation have been achieved
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119878119868119873119877 =
( )| |
| | frasl and 119878119868119873119877
= 119905 120588 |ℎ |
119879119900119905119886119897 = 119878119868119873119877 119878119868119873119877
119878119868119873119877 119878119868119873119877
+
where 119878119868119873119877 represented the signal-to-interference-plus-noise-
ratio of user 119898 that was decoded by 119880 for 119898119899120598119894 2+ and the
channels gain of 119880 denoted by |ℎ |
followed an exponential distribution
with the parameter 120577 = 120596 120575
Problem Formulation
Hence the base station should achieve and serve a better
communication for the users who are susceptible to security
threat from untrusted user the proposed system defined two
kinds of QoS efficiency measures that could be regarded to be
important for framing the issue In specific the study defined a pair
of OP to check the reliability of the QoS satisfaction In general
the pair OP is stated as the probability in which the obtainable
data rates dor the users equal to or greater than the least target
threshold The next metric also called as the SOP is the
probability that the non negative secrecy capacity obtained by the
trusted user is more than the threshold value
The following issue aimed at reducing the pair OP subjected to a
SOP factor for the user U1 that is provided by
min
119875
0 lt 119905 lt 05
119878119874119875 le 120573
in which 119875 119878119874119875 and 120573 are the pair OP SOP(119880 ) and the
permissible SOP threshold
4 PERFORMANCE ANALYSIS
Derivation of the Pair OP
With the use of Shannonrsquos capacity formula and considering
119862 and 119862
as the threshold capacities of users 119880 and
user 119880 respectively the OP of the pair could be provided
by
119875 = 1 minus 119876 119909119876
in which
120591 = 2
119898 120598 119894 2+
120601 =
( )
120601 =
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119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 1 120601 gt 120601
For having 120601 gt 120601 the constraint on
the power allocation factor (t) needs to be satisfied
(119905 gt
) and for this case 119876 could be obtained as
follows
119876 = exp (
)
lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
Case 2 120601 lt 120601
Like case 1 it was stated that opposite constraint on
a as (119905 lt
) and
119876 can be derived as follows
119876 = exp (
) 0 lt 119905 lt
0 119900119905ℎ119890119903119908119894119904119890
The OP of the NOMA pair
119875 = 1 minus 119891(119905)119896 (119905)
lt 119905 lt
1 minus 119891(119905)119896 (119905) 0 lt 119905 lt
in which
119891(119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
(
( ))
119896 (119905) = 119890119909119901
Derivation of SOP of 119880
With Shannonrsquos capacity formula the secrecy rate of
user 119880 was provided by
119878119862 = 119869 minus 119869
119869 = log (1 + 119879119900119905119886119897 (r (1)))
119869 = log (1 + 119879119900119905119886119897 (r (2)))
119878119862 is the non-negative secrecy capacity of 119880 Provided the
secrecy capacity in the SOP of 119880 is
119878119874119875 = 1 minus 120584119890
119860 =
120584 =
119879 - the user 119880 secrecy target rate
Theorem 1
Outage-optimal power allocation factor
119905 = radic
( )
In which 119908 =
119908 =
119911 = 1 + 120591
The minimum power allocation factor (119886 )
119905 =
(
)
The optimal OP of the NOMA pair under the SOP constraint
=
( )
( ( ))119890
( )
That is lt 0whih meant that the U1 (SOP) is a reducing function
Of t that results in the optimal power allocation factor that is
greater than 119905 for the satisfaction of secrecy constraining
factorPartially observable Markov decision process S is
represented as statesLet D is the channel features which is
consider here as actions the conditional transition probability
between states is regarded as T Reward function R is
calculated as the prediction of maximum capacity channel with
respect to data rate r = R(S x D) the agent receives an
observation o ϵ 120118 o isin Ω display style oin Omega that
depended on the new environment state S and on the just
took action d with the probability O(o|s d)
Reward received at time t is conveyed as r = R(S x D)
H is the belief states over POMDP states
119867 is the belief state transition function
119903 = 119877(119867 x 119863) is the reward function on the belief states
119861 (ℎ 119889 ℎ ) = sum Pr ( 120118 ℎ |ℎ 119889 119900) Pr(119900|119889 ℎ)
Pr(h |h d o) =
1 if the belief update with arguments h d o returns h 0 otherwise
The reward function is updated on the basis of the belief MDP
r (h d) = sum h(s) R(s d) isin
the agent focus on the largest expected immediate rewardin
other words the maximum capacity channel The section
analyse the accuracy of the analytical derivations under
various settings
Figure 3 The feasible pairing
The SOP of U1 with the increasing untrusted user U2 and
distance (d2) for several BS transmits Signal to Noise Ratio
at 120588 = minus20minus1020 119889119861is depicted in with a=005 and 01 and
d1=200m is depicted in the figure The results stated that the
U1(SOP) is a gradually reducing function as per d2 that
implies that the increasing value of d2 leads to the
improvement of the SOP of U1 Since the provided constant
threshold ϵ in SOP restraint U2must be situated at a larger
space when compared with threshold value to obtain the SOP
of U1 Apart from that it is normal that the high the target
secrecy rate rises the SOP of U1
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Figure 4 The Secrecy outage probability
Feasible Pairing in th SOP of pair OP and U1 with the
enhanced power allocation factor (a) in which d2 = 700 m d1
= 200 m 120588 = 15 dB and ϵ = 01 The results depicted that the
the pair OP and SOP of user U1 with increased a for two (d2)
various distances of the (U2) untrusted user The results
approve the convex nature of the pair OP and the SOP curve
is gradually decreasing on the basis of a Generally during the
increase in a the power assigned to the weak user message
decreases that minimize the ability of U2 for discriminating the
superior positioned signals thereby improving the SOP of U1
Figure 5 The Pair outage probability
Pair OP in case of rising U2 untrusted user in distance (d2)
for different base station transfer the signal to noise ratio(120588 =
5 15 25 dB) where a = 015 and d1 = 200 m
Figure 6The infeasible pairing of secrecy outage
probability of the pair OP and U1
The infeasible pairing of SOP (U1) and the pair outage
probability with the enhanced allocation of the power ad1(200
m)d2(300 m)120588 = 15dB and ϵ = 0
The figure 6 depicted that the
The figure 6 shows the similar plotting of the data by altering
the untrusted user location by transferring it to a BS closer
distance (d2 = 300 m) It also depicted that the U1 SOP
constraint of is disrupted at a because the SOP is more than ϵ
The accuracy is well-matched and verified with all range of
numerical simulation The results noticed that the efficiency is
based on the comparative locations of the two user with the
base station
Figure 7 The figure 7 depicts that SNR versus strictly
positive secrecy rate
The observed graph proves that the secrecy capacity
outperforms the existing techniques The proposed precoding
application increases the performance of the system The
transmission power of the system is the power required to
transmit a particular data When there is an increase in the
number of users there is the possibility of inference in the data
transmission and hence the efficiency of the data rate may be
affected Depending on these instances the efficiency of the
antenna capacity to withheld and accommodate the data
determined
Figure 8 The power radiated by BS antenna
In the figure 8with respect to the simulation setup the
precoding methods are performed based on the radiated
power per BS antenna is depicted The results observed the
better efficiency of the proposed system The proposed proves
to be better when compared with existing linear precoding
methods in the prescribed three metrics thereby stating that
MRT may be utilized for the the examination of the secrecy
capacity Our proposed technique spends less radiatated
power thereby increasing the overall capacity of the system
5 CONCLUSION The NOMA system decodes the messages of other user pairs
on the similar resources thereby promoting user possibility
The technique interprests a security threat in which the BS
serves the untrusted users The study analysed the SOP and
OP in both multi user and two user NOMA system in which the
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base station pairs the trusted user in closed type of
expressions The proposed (Interference mitigation using
POMDP) also enable the understanding of possibility of
achieving outage optimal efficiency to pair under SOP
constraints The numerical verifications verified the efficiency
of the analytical derivations
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Dynamic user clustering and power allocation for
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[2] ARAFA A SHIN W VAEZI M amp POOR H V
2019a Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
15 210-222
[3] ARAFA A SHIN W VAEZI M amp POOR H V
2019b Secure relaying in non-orthogonal multiple
access Trusted and untrusted scenarios IEEE
Transactions on Information Forensics and Security
[4] CAO K WANG B DING H LI T amp GONG F
2019 Optimal Relay Selection for Secure NOMA
Systems under Untrusted Users IEEE Transactions
on Vehicular Technology
[5] DANG S CHEN G amp COON J P 2018
Multicarrier relay selection for full-duplex relay-
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[6] DANG S COON J P amp CHEN G 2017 Outage
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spatially random decode-and-forward relays IEEE
Access 5 27514-27524
[7] FIANU S amp DAVIS L B 2018 A Markov decision
process model for equitable distribution of supplies
under uncertainty European Journal of Operational
Research 264 1101-1115
[8] FURQAN H M HAMAMREH J amp ARSLAN H
2019 Physical Layer Security for NOMA
Requirements Merits Challenges and
Recommendations arXiv preprint arXiv190505064
[9] HOU L ZHENG K CHATZIMISIOS P amp FENG Y
2018 A Continuous-Time Markov decision process-
based resource allocation scheme in vehicular cloud
for mobile video services Computer
Communications 118 140-147
[10] KOKSHOORN M CHEN H WANG P LI Y amp
VUCETIC B 2016 Millimeter wave MIMO channel
estimation using overlapped beam patterns and rate
adaptation IEEE Transactions on Signal Processing
65 601-616
[11] LIU Y ELKASHLAN M DING Z amp
KARAGIANNIDIS G K 2016 Fairness of user
clustering in MIMO non-orthogonal multiple access
systems IEEE Communications Letters 20 1465-
1468
[12] LV L CHEN J NI Q amp DING Z 2017 Design of
cooperative non-orthogonal multicast cognitive
multiple access for 5G systems User scheduling and
performance analysis IEEE Transactions on
Communications 65 2641-2656
[13] SUN Y NG D W K ZHU J amp SCHOBER R
2018 Robust and secure resource allocation for full-
duplex MISO multicarrier NOMA systems IEEE
Transactions on Communications 66 4119-4137
[14] ZHANG H YANG N LONG K PAN M
KARAGIANNIDIS G K amp LEUNG V C 2018
Secure communications in NOMA system
Subcarrier assignment and power allocation IEEE
Journal on Selected Areas in Communications 36
1441-1452
[15] ZHAO T LI G ZHANG G amp ZHANG C-X
Security-Enhanced User Pairing for MISO-NOMA
Downlink Transmission 2018 IEEE Global
Communications Conference (GLOBECOM) 2018
IEEE 1-6