A SEMINAR REPORT ON

THROUGHPUT IMPROVEMENT OF HIGH DENSITY RANDOMLY DEPLOYED IEEE 802.15.4 BASED WIRELESS

PERSONAL AREA NETWORKS

SUBMITTED TO UNIVERSITY OF PUNE, PUNEIN THE PARTIAL FULFILMENT OF THE REQUIREMENTS

FOR THE AWARD OF THE DEGREE

OF

DOCTOR OF PHILOSOPHY IN ENGINEERING (ELECTRONICS AND TELECOMMUNICATION)

BY

VATTI RAMBABU ARJUNARAO

DEPARTMENT OF ELECTRONICS AND TELECOMMUNICATION

STES’S

SINHGD COLLEGE OF ENGINEERING

VADAGAON BK., OFF. SINHGAD ROAD

PUNE – 411041

JULY 2012

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CERTIFICATE

This is to certify that the seminar report entitled

“THROUGHPUT IMPROVEMENT OF HIGH DENSITY RANDOMLY DEPLOYED IEEE 802.15.4 BASED WIRELESS PERSONAL AREA NETWORKS”

Submitted by

Vatti Rambabu Arjunarao

Is a bonafide work carried out by him under the supervision of Dr. A.N. Gaikwad and it is

approved for the partial fulfillment of the requirement of University of Pune for the award of

the Degree of Doctor of Philosophy in Engineering (Electronics and Telecommunication).

This seminar report has not been earlier submitted to any other Institute or University for the

award of any degree or diploma.

Prof. Dr. A.N. Gaikwad Prof. Dr.

Guide Head, Research Center

TABLE OF CONTENTS

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S.NO CONTENTSPAGE NO.

1. INTRODUCTION

2. LITERATURE SURVEY

3. THE IEEE 802.15.4 STANDARD

4.

RESEARCH METHODOLOGY

1. Research problem identification

2. Problem statement

3. Mathematical modeling

4. Identification and analysis of influence of the key factors

5. Defining objectives

6. Identification and analysis of alternate approaches.

7. Identification and selection of tools(Hardware and software)

8. Experiment Design

5. EXPECTED RESULTS AND CONCLUSION

6. SCOPE FOR FURTHER ESEARCH

7 REFERENCES

Throughput Improvement of High Density Randomly Deployed IEEE 802.15.4 Based Wireless Personal Area Networks

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1) INTRODUCTION

The IEEE 802.15.4 has been established as a global standard for low-rate, low cost, low-

power and short range wireless networking. Now- a-days, IEEE 802.15.4 is widely used in a

large number of applications, such as healthcare monitoring, Industrial automation, home

control, structural monitoring, remote metering applications. It is expected that the number of

applications utilizing IEEE 802.15.4 will increase exponentially. As result, many applications

of this standard would simultaneously operate in the same area, which leads to formation of

high density networks, with many nodes randomly deployed in a smaller geographical area.

The probability of collisions in such a high density randomly deployed networks is

also high. These collisions besides the interference due to the co-located similar Wireless

Personal Area Networks, other wireless networks operate in the same frequency band, and the

congestion in the network due to the increased traffic, degrade the throughput performance of

these Wireless Personal Area Networks.

The IEEE 802.15.4 standard originally does not provide any mechanism to prevent

occurrence of hidden node collisions. And, the Carrier Sense Multiple Access / Collision

avoidance (CSMA/CA), Media Access Control (MAC) scheme used in IEEE 802.15.4. gives

satisfactory performance for low traffic conditions but gives poor performance as the traffic

increases. Hence, there exists a strong need to improve the throughput performance of these

Low Rate Wireless Personal Area Networks.

2) LITERATURE SURVEY:

The research papers published in the IEEE Journals and other Journals/International

Conferences are studied and the summary of the survey is presented here.

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The IEEE 802.15.4 is an emerging worldwide standard for Low Rate Wireless

Personal Area Networks (WPAN). The main goal of this standard is to provide low rate, low

power, cost effective, flexible, reliable and scalable wireless Networks [1]. In future, many

applications of this standard would simultaneously operate in the same area, which leads to

formation of high density networks, with many nodes randomly deployed. The probability of

collisions in such a high density randomly deployed networks is also high. These collisions

degrade the throughput performance and energy efficiency of the network. The IEEE 802.15.4

based systems are designed to operate on low battery power. The current frame transmission

mechanism of the IEEE802.15.4 standard which adopts the blind random back-off mechanism

was designed to minimize the power consumption. However, it cannot provide satisfactory

performance in high density networks in which many number of nodes deployed randomly.

Y.C.Tseng. et al. in [2], have shown that, the probability of two randomly distributed

nodes in the radio coverage of a coordinator, that cannot hear each other is 41%. As a solution

to this problem, Shiann_Tsong Sheu, et.al.in [3], have developed a new multiple access

protocol with improved efficiency at the sub layer between the media access control layer and

the physical layer. The Carrier sense Multiple Access with Collision freeze (CSMA/CF )

protocol developed by the authors can achieve significant performance improvement in

throughput and energy efficiency. The number of frequency channels specified for

IEEE802.15.4 Wireless Personal area Networks (WPAN) does not suffice to operate a variety

of collocated WPAN applications that the standard is targeting.

Tae Hyun Kim et al. in [4], introduced, the concept of virtual channel to reduce the

collision probability and improve the through performance. The authors also have suggested

that the scheduler design that takes care of hidden node problem into account, which is

necessary in reducing the collisions in multiple WPANs. Uros Pesovic et al.[5], have

evaluated the influence of hidden node collisions on the network performance. Besides the

packet collisions and hidden node problems, the high density IEEE802.15.4 WPANs suffer

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from the beacon collisions. Jin-Wooo Kim et al in [6], have proposed a novel dynamic channel

management scheme using multi dimensional scheduling to avoid the beacon collision

problem. Ilenia Tinnirello et al. in [7], defined the distributed beacon scheduling policy able to

improve the performance of IEEE802.15.4 Media access control (MAC), avoiding collisions.

Bih-Yaw Shih et al. in [8], proposed two novel Hash Channel selection mechanisms to

decrease the number of collisions and to reduce the search time in the hash table.

Ling-jyh et al. in [9], analyzed the channel collision probabilities with focus on the

coexistence scenarios between one WPAN technology with another. Jae Yeol Ha et al. in [11]

have proposed two mechanisms to enhance throughput and energy efficiency of IEEE

802.15.4 CSMA/CA. The first one is an enhanced collision resolution (ECR) mechanism that

adjusts the back-off exponent (BE) based on both consecutive clear channel assessment

(CCA) busy results and a packet transmission. The second one is an enhanced back-off (EB)

mechanism that shifts the range of back-off counters by utilizing the CCA outcome. Tae Hyun

Kim et al., in [12]. Authors introduced virtual channel concept to maximize the coexistence

capability of WPANs and proposed two methods: (1) least collision super frame scheduler

(LC-scheduler), (2) less complex heuristics, and (3) virtual channel selector (VCS) to

efficiently manage multiple available logical channels. Chih-Kuang et al. in [13], have

introduced novel probabilistic transmission protocols for data intensive wireless sensor

networks, to alleviate network performance degradation due to excessive collisions and

retransmissions. Bih-Yaw Shih et al., in [14], have proposed a mechanism to enhance the

MAC channel selection to improve the throughput performance of the IEEE 802.15.4. Tae-Jin

Lee, et al., in [15], have analyzed MAC throughput limit of slotted CSMA/CA in IEEE

802.15.4 WPAN.

IEEE 802.15.4, in general uses a single channel for data transmission even though

multiple non-overlapped channels exist in the 2.4 GHz spectrum. The aggregate throughput of

these networks can be improved by using multiple channels that are available in the radio

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spectrum allocated by the standards. [16,17]. Paulo Cardieri, in [18], has done the interference

modeling in different layers. Lucia Lo Bello, et al. in [19], have developed a methodology to

evaluate cross channel interference. Ruitao Xu et al., in [20], have proposed global and local

channel assignment schemes to improve the throughput by avoiding Wi-Fi interference.

Jonwon Yoon, et al., in [21], have proposed data fragmentation scheme to reduce the collision

probability and to improve throughput.

Michael N. Krishnan, et al., in [22], have developed technique to improve throughput

of WLANs through collision probability estimation. Dimitrios J. Vergados, et al. in [23], have

developed a novel routing scheme based on residual energy and the available throughput in

order to balance the advantages of both the strategies. Yong Cui, et al.,in [24], have proposed

a probabilistic multi-path routing protocol for multiple flows, which can improve the network

throughput by selecting route with bigger effective bandwidth using higher probability.

Zawodniok. M, et al., in [25], have developed the decentralized, predictive congestion

control (DPCC) protocol for wireless sensor networks .The DPCC protocol reduces

congestion and improves performance over congestion detection and avoidance method. Jilin

Le., et al., in [26], have proposed the practical wireless network coding system, which

demonstrated that, by network coding, the throughput gain achieved is much higher .

Martin Petrova et al. in [27], have conducted experiments to measure the interference

of the IEEE 802.11g/n Wi-Fi access points on the IEEE 802.15.4, low rate WPANs. They

have observed that all the WPAN channels are affected by the transmission of Wi-Fi 802.11n,

as the bandwidth of the same is 40 MHz, and uses minimum of 16 dBm power for the signal

transmission. The 802.15.4 WPANs transmit at 0 dBm power level . The two non-

overlapping channels also will be affected as the CCA threshold level will be low.

3) IEEE 802.15.4. STANDARD OVERVIEW

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IEEE 802.15.4 is a standard for low cost, low power, and low-data rate transmission. This

standard uses CSMA-CA protocol for channel access. The main objectives of an LR-WPAN

are ease of installation, reliable data transfer, short-range operation, extremely low cost, and a

reasonable battery life, while maintaining a simple and flexible protocol.

3.1.Characteristics of LR-WPAN

1.Over-the-air data rates of 250 kb/s, 100kb/s, 40 kb/s, and 20 kb/s, 2.Star or peer-to-peer

operation, 3. Allocated 16-bit short or 64-bit extended addresses, 4.Optional allocation of

guaranteed time slots (GTSs), 5. Carrier sense multiple access with collision avoidance

(CSMA-CA) channel access, 6. Fully acknowledged protocol for transfer reliability, 7. Low

power consumption, 8.Energy detection (ED), 9. Link quality indication (LQI), 10. 16

channels in the 2450 MHz band, 30 channels in the 915 MHz band, and 3 channels in the 868

MHz band.

Two different device types can participate in an IEEE 802.15.4 network; a full-

function device (FFD) and a reduced-function device (RFD). The FFD can operate in three

modes serving as a personal area network (PAN) coordinator, a coordinator, or a device. An

FFD can talk to RFDs or other FFDs, while an RFD can talk only to an FFD. An RFD is

intended for applications that are extremely simple, such as a light switch or a passive infrared

sensor; they do not have the need to send large amounts of data and may only associate with a

single FFD at a time. Consequently, the RFD can be implemented using minimal resources

and memory capacity.

3.2. The PHY specification

The PHY is responsible for the following tasks:

Activation and deactivation of the radio transceiver, Energy detection (ED) within the current

channel, Link quality indicator (LQI) for received packets, Clear channel assessment (CCA)

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for carrier sense multiple access with collision avoidance (CSMA-CA), Channel frequency

selection, Data transmission and reception.

3.2.1. The standard specifies the following four PHYs:

1. An 868/915 MHz direct sequence spread spectrum (DSSS) PHY employing binary

phase-shift keying (BPSK) modulation.

2. An 868/915 MHz DSSS PHY employing offset quadrature phase-shift keying (O-

QPSK) modulation.

3. An 868/915 MHz parallel sequence spread spectrum (PSSS) PHY employing BPSK

and amplitude shift keying (ASK) modulation.

4. A 2450 MHz DSSS PHY employing O-QPSK modulation.

3.3. The MAC sub layer specification

This clause specifies the MAC sublayer of this standard. The MAC sublayer handles all access

to the physical radio channel and is responsible for the following tasks:

Generating network beacons if the device is a coordinator, Synchronizing to network beacons,

Supporting PAN association and disassociation, supporting device security, Employing the

CSMA-CA mechanism for channel access, Handling and maintaining the GTS mechanism,

Providing a reliable link between two peer MAC entities.

3.4. Network topologies

IEEE 802.15.4 LR-WPAN may operate in either of two topologies: The star topology or the

peer-to-peer topology.

3.4.1.Star network formation

The basic structure of a star network is illustrated in Figure 1. After an FFD is activated, it can

establish its own network and become the PAN coordinator. All star networks operate

independently from all other star networks currently in operation. This is achieved by

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choosing a PAN identifier that is not currently used by any other network within the radio

sphere of influence. Once the PAN identifier is chosen, the PAN coordinator allows other

devices, potentially both FFDs and RFDs, to join its network.

3.4.2.Peer-to-peer network formation

In a peer-to-peer topology, each device is capable of communicating with any other device

within its radio sphere of influence. One device is nominated as the PAN coordinator, for

instance, by virtue of being the first device to communicate on the channel. Further network

structures are constructed out of the peer-to-peer topology and it is possible to impose

topological restrictions on the formation of the network. An example of the use of the peer-to-

peer communications topology is the cluster tree. The cluster tree network is a special case of

a peer-to-peer network in which most devices are FFDs. An RFD connects to a cluster tree

network as a leaf device at the end of a branch because RFDs do not allow other devices to

associate. Any of the FFDs may act as a coordinator and provide synchronization services to

other devices or other coordinators. Only one of these coordinators can be the overall PAN

coordinator, which may have greater computational resources than any other device(s) in the

PAN. The PAN coordinator forms the first cluster by choosing an unused PAN identifier and

broadcasting beacon frames to neighboring devices. A contention resolution mechanism is

required if two or more FFDs simultaneously attempt to establish themselves as PAN

coordinators; however, such a mechanism is outside the scope of this standard.

3.5. Clear Channel Assessment:

The IEEE 802.15.4 PHY shall provide the capability to perform CCA according to at least one

of the following three methods:

CCA Mode 1: Energy above threshold. CCA shall report a busy medium upon detecting any

energy above the ED threshold.

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CCA Mode 2: Carrier sense only. CCA shall report a busy medium only upon the detection of

a signal with the modulation and spreading characteristics of IEEE 802.15.4. This signal may

be above or below the ED threshold.

CCA Mode 3: Carrier sense with energy above threshold. CCA shall report a busy medium

only upon the detection of a signal with the modulation and spreading characteristics of IEEE

802.15.4 with energy above the ED threshold.

3.6. Architecture

The IEEE 802.15.4 architecture is defined in terms of number of blocks in order to simplify

the standard. These blocks are called layers. Each layer is responsible for one part of the

standard and offers services to the higher layers. The layout of the blocks is based on the Open

System Interconnection (OSI) seven-layer model.

Fig.1. Architecture of IEEE 802.15.4 Standard

4. RESEARCH METHODOLOGY

The literature will be reviewed in the problem domain. The study of the factors

influencing the throughput performance of the IEEE 802.15.4 based Wireless Personal Area

Networks in high density and random node deployment scenarios will be done. The

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formulation of the mathematical model of the system will be done. Alternate methods for

obtaining the solution will be studied and analysed. A new method or technique will be

proposed based on the literature survey and study of the existing methods. The performance of

the proposed technique will be simulated and tested. The results obtained from the proposed

solution are analyzed and modifications will be done till the expected performance is

achieved. The performance of the technique is the validated with the existing benchmark

method.

4.1. Research Problem Identification: The IEEE 802.15.4 based wireless networks are

being widely used in various applications including industrial automation, home control, cable

replacement, consumer electronics, structural health monitoring, health care and wireless

sensor networks. The 802.15.4 standard operates in 3 frequency bands. One of them is the un-

licensed 2.4Ghz ISM band. Since this band is un – licensed, many Wireless Personal Area

Networks(WPAN) like 802.1( Bluetooth), 802.3 ( high data Rate Wireless Personal Area

Network), 802.6 (Wireless Body Area Networks), Micro wave ovens and Wireless Local Area

Networks (WLAN) 802.11 b/g ( Wi-Fi) are forced to share this frequency band. As a result of

increased applications of these WPANs and WLANs, the channel allocation conflicts are

bound exist among WPANs due to the limited number of channels supported by 802.15.4

WPAN. The co-existence problems will inevitable between WPANs and WLANs.

Moreover, the problems interference, collisions, do occur as the more number of applications

are working in the small geographical area. As the number of nodes increases, the hidden node

problem crops up. Besides these problems, the WPANs also face the congestion problem due

to the increased traffic in the network and limited buffer availability on the 802.15.4 nodes.

4.2. Research Problem statement

To Improve the Throughput of High Density Randomly Deployed IEEE 802.15.4 Based

Wireless Personal Area Networks.

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4.3. Mathematical modeling (Throughput)

Packet Delivery Rate (PDR) at the MAC layer, throughput, energy consumption are the

parameters used to estimate the performance of the WPANs.

4.3.1.One – hop direct transmission scheme:

The PDR of the one - hop transmission scheme is the packet successful rate on the direct link.

PDRa = 1- psd -------- (1)

Where, psd is the packet error rate on the direct channel, which is determined by the selected

rate Rsd, the given packet length and the instantaneous channel condition.

The throughput performance can be obtained by calculating the average number of

successfully transmitted payload information bits within average unit time consumed during

the transmission.

ɳa = PDRa

δ+R sd+L+LACK+SIFS+DIFS (2)

Where L = Length of the data packet

LACK = Length of the ACK packet

SIFS = Short Inter frame Spacing

DIFS = Data Inter frame Spacing

is the average backoff time before each data transmission, which is the half of the size of the

minimal contention window multiplied by the duration of the slot time.

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4.3.2.Two hop-transmission scheme

In the two – hop transmission, the data packet is received correctly at the destination node

only if both the first hop transmission on the parallel channel and the second hop transmission

on the relay channel are successful. Therefore, the PDR performance of the two-hop

transmission can be calculated as:

PDRb=(1−psr )+(1−prd) (3)

Where, psr and prd are the packet error rate on the parallel and relay channels respectively,

and can be determined accordingly by Rsr and Rrd in the given channel conditions.

The throughput ɳb=PDRbL

Db (4)

Where, Db is the time used for the two-hop transmission of the packet and expressed as:

Db=δ+L/R sr+LACK /R sr+SIFS+DIFS+(1−psr )¿)

(5)

4.4. Identification and analysis of influence of the key factors

Factors influencing the throughput of WPANs

Throughput is directly proportional to PDR and data transmission rate.

And inversely proportional to the , length of the ACK, and Inter frame spacing.

The length of ACK, SIFS and DIFS are defined by the MAC frame are constant. Therefore,

we can generalize that the throughput mostly depends on the PDR, and the length of the data

packet.

We can write ɳ = f( PDR, , L)

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CA B

Of these factors, the length of the data packet can be controlled by the user , is defined by

the IEEE 802.15.4 standard and can be manipulated. The factor PDR is affected by the various

factors, beyond the scope of control of the 802.15.4 WPAN.

4.4.1) the factors influencing the PDR of the WPAN are:

a) Hidden nodes:

A WPAN node is equipped with an Omni-directional antenna to permit random

deployment, as the actual sensing environment is very hard to predict. The common

practice in the WPANs is that the node, which wants to transmit data, listen the medium,

before it starts transmission. After ensuring, the medium is free, the node initiates the

transmission procedure. This kind of medium access operates smoothly, only, if the node

is capable to hear all the nodes which participate in network. If the nodes are located in

such a manner that, they are not able to hear each other are called hidden nodes.

Node ‘A’ radio range Collision zone Node’ C’ radio range

Fig.2. hidden nodes

Here node B is in the radio range of node A , but node C is not in the radio range of node A.

Node B is in the radio range of both node A and node B. Both the nodes A and C can

communicate with node B and if the both the nodes simultaneously transmit data to node B,

there will be collision at node B. This hidden node problem is starts degrading the network

performance as the density of the nodes in the network increases.

The hidden node problem is not addressed in the original IEEE 802.15.4 standard.

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In 802.11 WLANs hidden nodes can be tackled with the help of RTS/CTS handshake

procedure. The RTS/ CTS procedure needs more energy and adds to the overhead which

reduces the energy efficiency and also the throughput.

According to [2], [3] and [5], the probability, that two randomly distributed nodes in radio

range of central node cannot hear each other is as high as 41%.

Solving the hidden node problem for the densely deployed WPANs is a challenge to wireless

network researchers.

b) Packet Collisions:

Packet collision is a situation when two nodes simultaneously start transmission, and their

packets will collide at recipient node which would not be able to successfully receive any of

these packets. The collided packets will need to be re-transmitted which reduces the

throughput. In wired networks, this problem can be solved using collision detection

mechanisms. However, it is not possible to detect the collision in case of wireless networks as

the transmitter and receiver share much of the radio components including antenna.

d) Congestion:

Wireless multi-hop networks are formed by a set of nodes where communication

between two end nodes is carried out by hopping over multiple short wireless links. In such a

network, each node not only sends/receives packets to/from adjacent nodes, but also acts as a

router and forwards packets on behalf of other nodes. Therefore, in many cases, there will be

nodes which, due to their position in the network topology, are more likely to serve as relaying

nodes during the routing process. The increase in the traffic at any node due to the increased

number of nodes transmitting data, results in increasing of the queue sizes and thus packets

can be lost due to buffer overflow. This situation is called congestion.

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ch112405MHz

ch162430MHz

ch202450MHz

ch262480MHz

40MHz- 802.11n- ch9

20MHz-802.11g ch11-2462Mhz

IEEE802.15.4 channels(ISM)

0 dBm

16 dBm

This congestion causes packet loss due to limited buffer size of the nodes and delay due to re-

transmissions. Both of these parameters cause the throughput degradation.

Congestion avoidance is another challenge to the researchers in the WPAN research

community.

d) Interference:

Fig2. IEEE 802.15.4 and IEEE 802.11g/n channel allocation and PSD mask. [27]

The Wi-Fi 802.11b, 802.11g and 802.11n, the blue tooth 802.15.1, high data rate WPAN

802.3 and micro wave ovens and some other devices are also sharing the license free 2.4Ghz –

ISM band. The IEEE 802.15.4 WPAN channels are overlapped by the other co-existed Wi-Fi

and WPANs. The interference due to the Wi-Fi 802.11g and 802.11n are more severe, as the

power level used by these standards are minimum 16 dBm, whereas, the 802.15.4 standard

uses maximum transmission power level of 0 dBm. Because of the dense and random

deployment of these networks with higher transmission power levels will make the PDR of the

low power 802.15.4 networks to drop even to the level of 0% under heavy traffic conditions.

There are only two non-overlapped channels. Both the non-overlapping channels also suffer

from the less PDR due to the CCA procedure of 802.15.4 networks.

4.5. Defining the Research objectives

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1. To Study the influence of the collisions on the Throughput performance of the IEEE

802.15.4 based Wireless Personal Area Networks and to analyze the same for High

Density scenarios.

2. To study the probability of collisions in randomly deployed networks and analyze their

impact on the throughput performance of the network as the node density increases.

3. To study the influence of hidden nodes on the throughput performance of the network

as the node density increases with random deployment.

4. To study the influence of interference due to co-existed other wireless networks /or

congestion due to traffic on throughput performance of the network as the node

density increases.

5. To study the existing methods/ techniques to improve the throughput performance of

the conventional IEEE 802.15.4 based Wireless Personal Area Networks and their

limitations in High density and randomly deployed scenarios.

6. To develop a new method/ technique to improve the throughput in high density and

randomly deployed Wireless Personal Area Networks and verify the performance of

the developed method/ technique by simulations/ or experimentation.

4.6.Identification of alternate Methods/approaches.

1. Clear channel Assessment: There are three CCA modes. Mode 1 is the ED threshold

mode. In mode 2 and mode3, the CSMA-CA performs the CCA based on the signal

strength on the carrier. For low traffic, CSMA-CA gives good performance, but in

high traffic situations, the performance of CSMA-CA is poor. In the Co-existed

scenarios, the CCA fails as the threshold of the 802.15.4 is far less than the allowable

fall rate of signal strength of the 802.11n Wi-Fi systems.

2. Adaptive data rate control: As the 802.15.4 WPAN nodes are resource constrained,

the congestion can prevail in high density scenarios due to the small buffer size at the

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relay nodes. This congestion can be controlled to certain extent by the node by

implementing adaptive data rate control mechanism.

3. Virtual Channel Management for Densely deployed WPANs: The number of

channels specified for IEEE 802.15.4 WPAN is too few to operate many applications

in the same area. To overcome this, a virtual channel concept is introduced. A virtual

channel concept is basically created via superframe scheduling within the inactive

periods in a logical channel pre-occupied by other WPANs.

4. Multi Channel Multi Radio approach to improve throughput

5. Non-Orthogonal Multi Channel approach to improve throughput: The effect of

co-channel interference and inter channel interference are different. This method

adjusts the CCA threshold to enable the concurrent transmissions on adjacent non-

orhogonal channels. This improves the overall network throughput performance.

4.7.Identification and selection of tools(Hardware and software)

1. Hardware

i) Telos-B motes (IEEE 802.15.4)

ii) 802.11g/n access points

2. Software tools

i) Smart rf studio

ii) Network simulator-2

iii) MATLAB ver.9

4.8.Experiment Design

Experiments are designed to measure the interference impact of the IEEE 802.11g/n

access points by placing the access point within the range of the IEEE 802.15.4 WPANs

and a FTP traffic is generated. By varying the signal strength and distance of the

802.11g/n APs , the packet losses are calculated and the throughput is estimated.

5. Expected results and Conclusion

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A new technique has been developed to improve the throughput performance of the high

density randomly deployed IEEE 802.15.4 based Wireless Personal Area Networks. The

throughput of the High Density Randomly Deployed IEEE 802.15.4 based Wireless Personal

Area Network has been measured by simulation, with the existing technique, and with the new

technique developed separately, and the results were compared. The simulation results show

that, a 40% higher throughput has been achieved with the new technique when compared with

the existing technique under the same network conditions.

6. Scope for further Research

Throughput performance improvement of IEEE 802.15.4 WPANs in high density and

random node deployment scenarios has been carried out in this research. The research can

be further continued to improve the performance of LR-WPANs by extending the range by

proper node deployment strategies and by using the directional antennas, the beam

forming technique can also be adopted to enhance the range. The co-existence

performance can be improved by modifying the CCA threshold. The slotted CSMA/CA

can be improved by implementing linear increments in backoff time rather than the

exponential backoff.

7) References

[1]. IEEE. 802.15.4., Standard 2006.,Part 15.4: “ Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low Rate Wireless Personal area Networks (LR-WPANs)” , IEEE –SA Standards Board 2006.

[2]. Y.C.Tseng, S.Y.Ni.,and E.Y.Shih, “ Adaptive approaches to relieving broadcast storms in a wireless multihop mobile ad hoc network,”, IEEE Transactions on Computers, Vol.52.,no.5, pp.545-557, May 2003.

[3]. Shiann-Tsong Sheu, Yun-Yen Shih and Wei-Tsong Lee., “CSMA/CF Protocol for IEEE 802.15.4 WPANs”, IEEE Transactions on Vehicular Technology, Vol.58, no.3, March2009. pp,1501-1516.

[4]. Tae Hyun Kim, Jae Yeol Ha and Sunghyun Choi., “Improving Spectral and Temporal Efficiency of Collocated IEEE 802.15.4 LR-WPANs”, IEEE Transactions on mobile Computing, Vol. 8, No. 12, Dec. 2009, pp 1596-1609.

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[5]. Uros Pesovic, Joze Mohorko, Karl Benkic, Zarko Cucej, “Effect of hidden Nodes in IEEE 802.15.4/ZigBee Wireless Sensor Networks”, 17th Telecommunications forum, TELFOR 2009, Serbia, Belgrade, Nov 24-26, 2009, pp.161-164.

[6].Jin-Woo Kim, Jihoon Kim and Doo-Seop Eom., “Multi-Dimentional Channel Management Scheme to Avoid Beacon Collision in LR-WPAN”, IEEE Transactions on Consumer Electronics, Vol. 54, no.2, May 2008, pp.396-404.

[7].Ilenia Tinnirello, Laura Giarre, Francesco Mineo, “Opportunistic Synchronization for Improving IEEE 802.15.4 MAC Performance in Chain Topologies”, Ecologic Vehicles. Renewable Energies, Monaco, March25-28, 2010.

[8].Bih-Yaw Shih, Chen-Yuan Chen, Chia-Hung Shih and Jyun-Ying Tseng, “The development of enhancing mechanisms for improving the performance of IEEE 802.15.4”, International journal of Physical Sciences ,June2010,Vol.5(6), pp.884-897.

[9].Ling-jyh Chen, Tony Sun, Mario Gerla, “ Modeling Channel Conflict Probabilities between IEEE 802.15 based Wireless Personal Area networks.”, IEEE Conference on Communications (ICC’06), Istanbul, Turkey, January 2006, pp.1-6.

[10]. Rodolfo de Paz Alberola, Berta Carballido Villaverde and Dirk Pesch., “Distributed Duty cycle Management (DDCM) for IEEE 802.15.4 Beacon enabled Wireless Mesh sensor networks.”, The 8th IEEE International Conference on Mobile Ad-hoc and Sensor Systems, IEEE MASS 2011, October 17-22, 2011, velencia, Spain, pp.721-726.

[11]. Jae Yeol Ha, Kim, T.H.; Hong Seong Park; Sunghyun Choi; Wook Hyun Kwon “An

Enhanced CSMA-CA Algorithm for IEEE 802.15.4 LR-WPANs.”, IEEE Communication

Letters, May 2007, Volume: 11 , Issue: 5 Page(s): 461 – 463.

[12]. Tae Hyun Kim, Jae Yeol Ha, Sunghyun Choi and Wook Hyun Kwon, “Virtual Channel Management for Densely Deployed IEEE 802.15.4 LR-WPANs.”, Fourth Annual IEEE International Conference on Pervasive Computing and Communications-2006, 13-17 March 2006,pages: 11pp -115.

[13]. Chih-Kuang Lin, Vladimir, “Efficient Hybrid Channel Access for Data Intensive Sensor Networks.”, IEEE -21st International Conference on Advanced Information Networking and Applications Workshops-2007, AINAW’07, 21-23 May 2007, Niagara Falls, Ontario, Canada Vol.2, pp. 659-664.

[14]. Bih-Yaw Shih, Chin-Jui Chang, Ai-Wei-Chen and Chen-Yuan Chen, “Enhanced Mac Channel Selection to improve performance of IEEE 802.15.4.”, International Journal of Innovative Computing, Information and Control, Volume.6, Number.12, December 2010, pp.5511-5526.

[15]. Tae-Jin Lee, Hae Rim Lee and Min Young Chung, “MAC Throughput Limit Analysis of Slotted CSMA/CA in IEEE 802.15.4 WPAN.” , IEEE Communications Letters, Vol. 10, no. 7, July 2006 , pp. 561-563.

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[16]. Zainaldin, A. Lambadaris, I., Nandy, B., “ Video over Wireless Zigbee Networks: Multi-Channel Multi-Radio Approach.”, IEEE International Conference on Wireless

Communications and Mobile Computing, 2008. IWCMC '08. 6-8 Aug. 2008, pp. 882 – 887.

[17]. Nadeem Ahmed, Salil S.Kanhere, and Sajay Jha, “Mitigating Effect of Interference in Wireless Sensor Networks”,proceedings of 35th Annual IEEE Conference on Local Computer Networks, LCN 2010, Denver, Colorado, pp.160-167.

[18]. Paulo Cardieri, “Modeling Interference in Wireless Ad Hoc Networks.”, IEEE Communications Surveys & Tutorials, Vol.12, no. 4, Fourth Quarter 2010- 2010 IEEE, pp. 551-571.

[19]. Lucia Lo Bello and Emanuele Toscano., “Coexistence Issues of Multiple Co-Located IEEE 802.15.4/ZigBee Networks Running on Adjacent Radio Channels in Industrial Environments.”, IEEE Transactions on Industrial Informatics, Vol.5, No.2, May 2009, pp.157-167.

[20]. Ruitao Xu, Gaotao Shi, Jun Luo, Zenghua Zhao and Yantai Shu, “ MuZi: Multi Channel ZigBee Networks for avoiding WiFi interference”,IEEE -2011-International conferences on Internet of things, and cyber, Physical and Social Computing,pp.323-329.

[21]. Jongwon Yoon, Hyogon Kim and Jeong – Gil Ko, “Data Fragmentation Scheme in IEEE 802.15.4 Wireless Sensor Networks,”, IEEE 65th International Conference on Vehicular Technology-2007, VTC2007,22-25 April 2007, Dublin, Irland, pp.26-30.

[22]. Michael N. Krishnan, and Avideh Zakhor, “Throughput improvement in 802.11 WLANs using Collision Probability Estimates in Link Adaptation”, IEEE, Wireless Communication and Networking Conference(WCNC),2010,pp.1-6.

[23]. Dimitrios J. Vergados, Aggeliki Sgora, Dimitrios D. Vergados, “ Energy and throughput efficiency in Wireless Multihop Networks”, IEEE GLOBECOM - 2010 workshop on mobile Computing and Emerging Communication Networks.pp.1276-1280.

[24]. Yong Cui , Wenji Hu   Tarkoma, S. ;  Yla-Jaaski, A. “Probabilistic routing for multiple flows in wireless multi-hop networks.”, IEEE 34th Conference on Local Computer Networks, 2009. LCN 2009, 20-23 Oct. 2009, 261 – 264.

[25]. Zawodniok.M., Jagannathan, S.,” Predictive Congestion Control Protocol for Wireless Sensor Networks.”, IEEE Transactions on Wireless Communications, November 2007, Volume: 6 , Issue: 11 , Page(s): 3955 – 3963.

[26]. Jillin Le, Lui.J C.S, Dah-Ming Chiu, “DCAR: Distributed Coding-Aware Routing in Wireless Networks.”, IEEE Transactions on Mobile Computing – April 2010, Vol.9 Issue-4, pp. 596-608.

[27]. Marina Petrova, Lili Wu, Petri Mahonen and Janne Riihijarvi, “ Intereference Measurements on Performance Degradation between Colocated IEEE 802.11g/n and IEEE 802.15.4 Networks”. Proceedings of the sixth international Conference on Networking (ICN’07). 2007.

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Research Candidate Research Guide

Mr. Rambabu A.Vatti Prof.(Dr.) A.N.Gaikwad

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