NS2 PROJECTS ABSTRACT

MANNET:

1. Leveraging Social Networks for P2P Content-Based File

Sharing in Disconnected MANETs

ABSTRACT

Current peer-to-peer (P2P) file sharing methods in mobile ad hoc networks

(MANETs) can be classified into three groups: flooding-based, advertisement-

based, and social contact-based. The first two groups of methods can easily have

high overhead and low scalability. They are mainly developed for connected

MANETs, in which end-to-end connectivity among nodes is ensured. The third

group of methods adapts to the opportunistic nature of disconnected MANETs but

fails to consider the social interests (i.e., contents) of mobile nodes, which can be

exploited to improve the file searching efficiency. In this paper, we propose a P2P

contentbased file sharing system, namely SPOON, for disconnected MANETs. The

system uses an interest extraction algorithm to derive a nodes interests from its

files for content-based file searching. For efficient file searching, SPOON groups

common-interest nodes that frequently meet with each other as communities. It

takes advantage of node mobility by designating stable nodes, which have the most

frequent contact with community members, as community coordinators for

intracommunity searching, and highly mobile nodes that visit other communities

frequently as community ambassadors for intercommunity searching. An interest-

oriented file searching scheme is proposed for high file searching efficiency.

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Additional strategies for file prefetching, querying-completion, and loop

prevention, and node churn consideration are discussed to further enhance the file

searching efficiency. We first tested our system on the GENI Orbit test bed with a

real trace and then conducted event-driven experiment with two real traces and

NS2 simulation with simulated disconnected and connected MANET scenarios.

The test results show that our system significantly lowers transmission cost and

improves file searching success rate compared to current methods.

2. Optimal Multicast Capacity and Delay Tradeoffs in MANETs

ABSTRACT

In this paper, we give a global perspective of multicast capacity and delay

analysis in Mobile Ad Hoc Networks (MANETs). Specifically, we consider four

node mobility models: (1) two-dimensional i.i.d. mobility, (2) two-dimensional

hybrid random walk, (3) one-dimensional i.i.d. mobility, and (4) one-dimensional

hybrid random walk. Two mobility time-scales are investigated in this paper: (i)

fast mobility where node mobility is at the same time-scale as data transmissions

and (ii) slow mobility where node mobility is assumed to occur at a much slower

time-scale than data transmissions. Given a delay constraint D, we first

characterize the optimal multicast capacity for each of the eight types of mobility

models, and then we develop a scheme that can achieve a capacity-delay tradeoff

close to the upper bound up to a logarithmic factor. In addition, we also study

heterogeneous networks with infrastructure support.

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3. Delay and Capacity Analysis in MANETs with Correlated

Mobility and f-cast Relay

ABSTRACT

Many studies have presented the order sense results of information

transmission capacity and packet delivery delay in mobile ad hoc networks

(MANETs). To achieve the fundamental understanding of MANETs, we focus on

deriving the closed-form expressions of the network capacity and end-to-end delay.

A MANET with the generalized correlated mobility model is considered in this

paper, where the mobility of nodes clustered in one group is confined within a

specified area, and multiple groups move uniformly across the network. We also

leverage limited packet redundancy to speed up the packet transmission, i.e., each

source node is allowed to distribute at most f copies of each packet in its delivery

process. Specifically, we first propose an effective multi-hop schedulingrouting

scheme under the correlated mobility model, and then develop the closed-form

expressions of both per node throughput capacity and expected end-to-end delay.

We further explore the trade-off between throughput capacity and packet delay by

using packet redundancy f. The simulation studies validate our theoretical results.

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4. A New Distributed Application and Network Layer Protocol

for VoIP in Mobile Ad Hoc Networks

ABSTRACT

In this work a new protocol for Voice over IP (VoIP) transmissions in

wireless ad-hoc networks is proposed. Distributed architecture is necessary when

dealing with dynamic environments, such as ports or battlefields, where creating

infrastructures becomes expensive or impossible. Mobile Ad-hoc NETworks

(MANETs) are based on a peer-to-peer approach and each node participates in the

organization of the whole network. VoIP over MANETs is a challenging issue due

to the intrinsic distributed nature of the existing peer-to-peer paradigm. This paper

proposes a new protocol,capable of ensuring a Quality of Service (QoS) level for

VoIP calls over a MANET and to manage a higher number of calls in the system.

Novel metric and utility functions are proposed to perform the best path selection

from source to destination nodes, respecting the QoS parameters for VoIP quality.

In particular, an objective metric such as R-factor is considered and a flexibility

index is defined, in order to maximize the number of acceptable VoIP calls.

Performance evaluation shows that the proposed approach led to better network

management in terms of admitted calls and respected QoS constraints.

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5. Maximizing P2P File Access Availability in Mobile Ad hoc

Networks Though Replication for Efficient File Sharing

ABSTRACT

File sharing applications in mobile ad hoc networks (MANETs) have

attracted more and more attention in recent years. The efficiency of file querying

suffers from the distinctive properties of such networks including node mobility

and limited communication range and resource. An intuitive method to alleviate

this problem is to create file replicas in the network. However, despite the efforts

on file replication, no research has focused on the global optimal replica creation

with minimum average querying delay. Specifically, current file replication

protocols in mobile ad hoc networks have two shortcomings. First, they lack a rule

to allocate limited resource to different files in order to minimize the average

querying delay. Second, they simply consider storage as resource for replicas, but

neglect the fact that the file holders frequency of meeting other nodes also plays

an important role in determining file availability. Actually, a node that has a higher

meeting frequency with others provides higher availability to its files. This

becomes even more evident in sparsely distributed MANETs, where nodes meet

disruptively. In this paper, we introduce a new concept of resource for file

replication, which considers both node storage and meeting frequency. We

theoretically study the influence of resource allocation on the average querying

delay and derive a resource allocation rule to minimize the average querying delay.

We further propose a distributed file replication protocol to realize the proposed

rule. Extensive trace-driven experiments with synthesized traces and real traces

show that our protocol can achieve shorter average querying delay at a lower cost

than current replication protocols.

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6. AASR: Authenticated Anonymous Secure Routing for

MANETs in Adversarial Environments

ABSTRACT

Anonymous communications are important for many applications of the

mobile ad hoc networks (MANETs) deployed in adversary environments. A major

requirement on the network is to provide unidentifiability and unlinkability for

mobile nodes and their traffics. Although a number of anonymous secure routing

protocols have been proposed, the requirement is not fully satisfied. The existing

protocols are vulnerable to the attacks of fake routing packets or denial-of-service

(DoS) broadcasting, even the node identities are protected by pseudonyms. In this

paper, we propose a new routing protocol, i.e., authenticated anonymous secure

routing (AASR), to satisfy the requirement and defend the attacks. More

specifically, the route request packets are authenticated by a group signature, to

defend the potential active attacks without unveiling the node identities.The key-

encrypted onion routing with a route secret verification message, is designed to

prevent intermediate nodes from inferring a real destination. Simulation results

have demonstrated the effectiveness of the proposed AASR protocol with

improved performance as compared to the existing protocols.

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7. Security Enhancements for Mobile Ad Hoc Networks with

Trust Management Using Uncertain Reasoning

ABSTRACT

The distinctive features of mobile ad hoc networks (MANETs),

including dynamic topology and open wireless medium, may lead MANETs

suffering from many security vulnerabilities. In this paper, using recent advances

in uncertain reasoning originated from artificial intelligence community, we

propose a unified trust management scheme that enhances the security in

MANETs. In the proposed trust management scheme, the trust model has two

components: trust from direct observation and trust from indirect observation. With

direct observation from an observer node, the trust value is derived using Bayesian

inference, which is a type of uncertain reasoning when the full probability model

can be defined. On the other hand, with indirect observation, also called

secondhand information that is obtained from neighbor nodes of the observer node,

the trust value is derived using the Dempster-Shafer theory, which is another type

of uncertain reasoning when the proposition of interest can be derived by an

indirect method. Combining these two components in the trust model, we can

obtain more accurate trust values of the observed nodes in MANETs. We then

evaluate our scheme under the scenario of MANET routing. Extensive simulation

results show the effectiveness of the proposed scheme. Specifically, throughput

and packet delivery ratio can be improved significantly with slightly increased

average end to- end delay and overhead of messages.

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VANNET:

1. We Can Deliver Messages to Far Vehicles

ABSTRACT

Vehicular ad hoc networks (VANETs) enable vehicles to communicate

with each other but require efficient and robust routing protocols for their success.

In this paper, we exploit the infrastructure of roadside units (RSUs) to efficiently

and reliably route packets in VANETs. Our system operates by using vehicles to

carry and forward messages from a source vehicle to a nearby RSU and, if needed,

route these messages through the RSU network and, finally send them from an

RSU to the destination vehicle. Our system is mostly critical for users who are far

apart and want to communicate using their vehicles onboard units. Many recent

paradigms, like social networks, will greatly benefit from a system like ours to

enable users on the road to exchange different types of data.We evaluate the

performance of our system using the ns2 simulation platform and compare our

scheme to existing solutions. The results prove the feasibility and efficiency of our

scheme.

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2. VECOS: A Vehicular Connection Steering Protocol

ABSTRACT

Thanks to their worldwide deployments, 3GPP mobile networks,

particularly Long Term Evolution, are gaining lots of momentum, so are LTE-

connected vehicles. Whilst one may envision an LTE-connected vehicle as a nicely

designed vehicle with sophisticated equipment, a conventional vehicle with a

person, using an LTE-enabled smart phone or tablet, on board can be logically

qualified for an LTE-connected vehicle. Maintaining an acceptable QoS/QoE

(Quality of Experience) of LTE services for a user on board a moving vehicle is a

challenging problem. One approach for that is to anticipate QoS/QoE degradation

and to exploit the different radio access technologies, such as WiFi, that may be

available at an LTE-connected vehicle, or in general at an LTE-enabled User

Equipment (UE) on board the vehicle. For this purpose, this paper introduces a

complete framework that proactively defines QoS/QoE-aware policies for LTE-

connected vehicles (UEs) to select the most adequate radio access, out of the

available ones (e.g., WiFi and LTE), that maximizes QoE throughout the mobility

path. The policies are communicated to the users following 3GPP standards and

are enforced by the UEs. They take into account the service type, the mobility

feature, and the traffic dynamics over the backhauls of the different available

accesses. Two different models were proposed to model the network selection

process. The first one is based on Multiple Attribute Decision Making (MADM)

techniques, while the second one is based on Markov Decision Process (MDP).

Moreover, the network selection process is modeled using a Time Continuous

Markov Chain and the performance of the proposed framework (VECOS) is

extensively evaluated through NS2-based simulations considering the case of two

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wireless access technologies, namely WiFi and cellular networks. The obtained

results illustrate that in comparison to conventional vertical handoff mechanisms

wherebyWiFi is always selected whenever it becomes available, the proposed

framework ensures better QoS and achieves better QoE throughout the time of the

received service and the mobility path of the user, and that is even in case of errors

in the prediction of the users mobility.

LOCALIZATION:

1. Cooperative Positioning and Tracking in Disruption Tolerant

Networks

ABSTRACT:

With the increasing number of location-dependent applications,

positioning and tracking a mobile device becomes more and more important to

enable pervasive and context-aware service. While extensive research has been

performed in physical localization and logical localization for satellite, GSM and

WiFi communication networks where fixed reference points are densely-deployed,

positioning and tracking techniques in a sparse disruption tolerant network (DTN)

have not been well addressed. In this paper, we propose a decentralized

cooperative method called PulseCounting for DTN localization and a probabilistic

tracking method called ProbTracking to confront this challenge. PulseCounting

evaluates the user walking steps and movement orientations using accelerometer

and electronic compass equipped in cellphones. It estimates user location by

accumulating the walking segments, and improves the estimation accuracy by

exploiting the encounters of mobile nodes. Several methods to refine the location

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estimation are discussed, which include the adjustment of trajectory based on

reference points and the mutual refinement of location estimation for encountering

nodes based on maximum-likelihood. To track user movement, the proposed

ProbTracking method uses Markov chain to describe movement patterns and

determines the most possible user walking trajectories without full record of user

locations. We implemented the positioning and tracking system in Android phones

and deployed a testbed in the campus of Nanjing University. Extensive

experiments are conducted to evaluate the effectiveness and accuracy of the

proposed methods, which show an average deviation of 9m in our system

compared to GPS.

2. Enhanced Inertial-Aided Indoor Tracking System for Wireless

Sensor Networks: A Review

ABSTRACT

In recent years, there has been a growing interest in localization

algorithms for indoor environments. In this paper, we have developed an enhanced

filtering method for indoor positioning and tracking applications using a wireless

sensor network. The method combines position, speed, and heading measurements

with the aim of achieving more accurate position estimates both in the short and

the long term. Using as a base, the well-known extended Kalman filter, we have

incorporated two novel measurement covariance matrix tuning methods. The

power threshold covariance matrix tuning method and the distance statistics

covariance matrix tuning method, both based on the statistical characteristics of the

distance estimations. In addition, we take into account the inertial measurements

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obtained from a nine-degrees of freedom inertial measurement unit. The system

has been validated in real scenarios and results show that it provides long-term

accuracy, that is, the accuracy remains below 1 m during a 20-min test. In

summary, our methods benefit from the reduced observation error of the inertial

sensors in the short term and extend it over a long period of time.

WIRELESS NETWORKS:

1. A QoS-Oriented Distributed Routing Protocol for Hybrid

Wireless Networks

ABSTRACT

As wireless communication gains popularity, significant research has

been devoted to supporting real-time transmission with stringent Quality of Service

(QoS) requirements for wireless applications. At the same time, a wireless hybrid

network that integrates a mobile wireless ad hoc network (MANET) and a wireless

infrastructure network has been proven to be a better alternative for the next

generation wireless networks. By directly adopting resource reservation-based QoS

routing for MANETs, hybrids networks inherit invalid reservation and race

condition problems in MANETs. How to guarantee the QoS in hybrid networks

remains an open problem. In this paper, we propose a QoS-Oriented Distributed

routing protocol (QOD) to enhance the QoS support capability of hybrid networks.

Taking advantage of fewer transmission hops and anycast transmission features of

the hybrid networks, QOD transforms the packet routing problem to a resource

scheduling problem. QOD incorporates five algorithms: 1) a QoS-guaranteed

neighbor selection algorithm to meet the transmission delay requirement, 2) a

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distributed packet scheduling algorithm to further reduce transmission delay, 3) a

mobility-based segment resizing algorithm that adaptively adjusts segment size

according to node mobility in order to reduce transmission time, 4) a traffic

redundant elimination algorithm to increase the transmission throughput, and 5) a

data redundancy elimination-based transmission algorithm to eliminate the

redundant data to further improve the transmission QoS. Analytical and simulation

results based on the random way-point model and the real human mobility model

show that QOD can provide high QoS performance in terms of overhead,

transmission delay, mobility-resilience, and scalability.

2. Snapshot and Continuous Data Collection in Probabilistic

Wireless Sensor Networks

ABSTRACT

Data collection is a common operation of Wireless Sensor Networks

(WSNs), of which the performance can be measured by its achievable network

capacity. Most existing works studying the network capacity issue are based on the

unpractical model called deterministic network model. In this paper, a more

reasonable model, probabilistic network model, is considered. For snapshot data

collection, we propose a novel Cell-based Path Scheduling (CPS) algorithm that

achieves capacity of in the sense of the worst case and order-

optimal capacity in the sense of expectation, where n is the number of sensor

nodes, ! is a constant, and W is the data transmitting rate. For continuous data

collection, we propose a Zone-based Pipeline Scheduling (ZPS) algorithm. ZPS

significantly speeds up the continuous data collection process by forming a data

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Transmission pipeline, and achieves a capacity gain of n or n=

log n ln n times better than the optimal capacity of the snapshot data collection

scenario in order in the sense of the worst case, where N is the number of

snapshots in a continuous data collection task. The simulation results also validate

that the proposed algorithms significantly improve network capacity compared

with the existing works.

3. Neighbor Table Based Shortcut Tree Routing in ZigBee

Wireless Networks

ABSTRACT

The ZigBee tree routing is widely used in many resource-limited devices

and applications, since it does not require any routing table and route discovery

overhead to send a packet to the destination. However, the ZigBee tree routing has

the fundamental limitation that a packet follows the tree topology; thus, it cannot

provide the optimal routing path. In this paper, we propose the shortcut tree routing

(STR) protocol that provides the near optimal routing path as well as maintains the

advantages of the ZigBee tree routing such as no route discovery overhead and low

memory consumption. The main idea of the shortcut tree routing is to calculate

remaining hops from an arbitrary source to the destination using the hierarchical

addressing scheme in ZigBee, and each source or intermediate node forwards a

packet to the neighbor node with the smallest remaining hops in its neighbor table.

The shortcut tree routing is fully distributed and compatible with ZigBee standard

in that it only utilizes addressing scheme and neighbor table without any changes

of the specification. The mathematical analysis proves that the 1-hop neighbor

information improves overall network performances by providing an efficient

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routing path and distributing the traffic load concentrated on the tree links. In the

performance evaluation, we show that the shortcut tree routing achieves the

comparable performance to AODV with limited overhead of neighbor table

maintenance as well as overwhelms the ZigBee tree routing in all the network

conditions such as network density, network configurations, traffic type, and

the network traffic.

4. An Energy-Balanced Routing Method Based on Forward-Aware

Factor for Wireless Sensor Networks

ABSTRACT

As an important part of industrial application (IA), the wireless sensor

network (WSN) has been an active research area over the past few years. Due to

the limited energy and communication ability of sensor nodes, it seems especially

important to design a routing protocol for WSNs so that sensing data can be

transmitted to the receiver effectively. An energy-balanced routing method based

on forward-aware factor (FAF-EBRM) is proposed in this paper. In FAF-EBRM,

the next-hop node is selected according to the awareness of link weight and

forward energy density. Furthermore, a spontaneous reconstruction mechanism for

local topology is designed additionally. In the experiments, FAFEBRMis

compared with LEACH and EEUC, experimental results show that FAF-EBRM

outperforms LEACH and EEUC, which balances the energy consumption,

prolongs the function lifetime and guarantees high QoS of WSN.

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5. Enhanced Inertial-Aided Indoor Tracking System for Wireless

Sensor Networks: A Review

ABSTRACT

In recent years, there has been a growing interest in localization

algorithms for indoor environments. In this paper, we have developed an enhanced

filtering method for indoor positioning and tracking applications using a wireless

sensor network. The method combines position, speed, and heading measurements

with the aim of achieving more accurate position estimates both in the short and

the long term. Using as a base, the well-known extended Kalman filter, we have

incorporated two novel measurement covariance matrix tuning methods. The

power threshold covariance matrix tuning method and the distance statistics

covariance matrix tuning method, both based on the statistical characteristics of the

distance estimations. In addition, we take into account the inertial measurements

obtained from a nine-degrees of freedom inertial measurement unit. The system

has been validated in real scenarios and results show that it provides long-term

accuracy, that is, the accuracy remains below 1 m during a 20-min test. In

summary, our methods benefit from the reduced observation error of the inertial

sensors in the short term and extend it over a long period of time.

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