ANALYSIS AND OPTIMIZATION OF ROUTING ......CERTIFICATE I certify that the work incorporated in the...

ANALYSIS AND OPTIMIZATION OFROUTING TECHNIQUES FOR WIRELESS

AD-HOC NETWORKS

A Thesis submitted to Gujarat Technological University

for the Award of

Doctor of Philosophy

in

Electronics and Communication Engineering

byBhupendra Parmar

Enrollment No. 129990911002

under supervision ofDr. Kishor G. Maradia

GUJARAT TECHNOLOGICAL UNIVERSITY,AHMEDABAD

December - 2018

ANALYSIS AND OPTIMIZATION OFROUTING TECHNIQUES FOR WIRELESS

AD-HOC NETWORKS

A Thesis submitted to Gujarat Technological University

for the Award of

Doctor of Philosophy

in

Electronics and Communication Engineering

byBhupendra Parmar

Enrollment No. 129990911002

under supervision ofDr. Kishor G. Maradia

GUJARAT TECHNOLOGICAL UNIVERSITY,AHMEDABAD

December - 2018

c© Bhupendra Parmar

i

DECLARATION

I declare that the thesis entitled Analysis and optimization of routing tech-

niques for wireless ad-hoc networks submitted by me for the degree of Doctor

of Philosophy is the record of research work carried out by me during the period

from 2012 to 2018 under the supervision of Dr. Kishor G. Maradia (Super-

visor) 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:.......................

Name of Research Scholar: Bhupendra Parmar

Place: Dahod (Gujarat), India.

ii

CERTIFICATE

I certify that the work incorporated in the thesis Analysis and optimization of

routing techniques for wireless ad-hoc networks submitted by Bhupendra

Parmar was carried out by the candidate under my supervision/guidance. To the

best of my knowledge: (i) the candidate has not submitted the same research work

to any other institution for any degree/diploma, 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:.........................

Name of Supervisor: Dr. Kishor G. Maradia

Place: Gandhinagar (Gujarat), India.

iii

Course-work Completion Certificate

This is to certify that Mr. Bhupendra Parmar enrolment no. 129990911002

is a PhD scholar enrolled for PhD program in the branch Electronics and Com-

munication Engineering of Gujarat Technological University, Ahmedabad.

(Please tick the relevant option(s))

� He/She has been exempted from the course-work (successfully completed

during M.Phil Course)

� He/She has been exempted from Research Methodology Course only (suc-

cessfully completed during M.Phil Course)

� He/She has successfully completed the PhD course work for the partial re-

quirement for the award of PhD Degree. His/ Her performance in the course

work is as follows-

Grade Obtained in Research Methodology(PH001)

Grade Obtained in Self Study Course(Core Subject)

(PH002)

BC BB

Supervisor’s Sign

(Dr. Kishor G. Maradia)

iv

ORIGINALITY CERTIFICATE

It is certified that PhD Thesis titled Analysis and optimization of routing

techniques for wireless ad-hoc networks by Bhupendra Parmar has been

examined by us. We undertake the following:

(a) Thesis has significant new work / knowledge as compared already published

or are 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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(copy of originality report attached) and found within limits as per GTU

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Signature of the Research Scholar:........................ Date:.................


Place: Dahod (Gujarat), India.

Signature of Supervisor...................................... Date.....................


Place: Gandhinagar (Gujarat), India.

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Turnitin Originality Report

vi

vii

viii

PhD THESIS Non-Exclusive License to GUJARATTECHNOLOGICAL 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, Bhupendra Parmar having

Enrollment No.: 129990911002 hereby grant a non-exclusive, royalty free and

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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.

ix

(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 rights granted by me

to my University in this nonexclusive license.

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including all policy matters related to authorship and plagiarism.

Signature of the Research Scholar:..............................................


Date:................................ Place: Dahod (Gujarat), India.

Signature of Supervisor:..............................................


Date:................................ Place: Gandhinagar (Gujarat), India.

Seal:

x

THESIS APPROVAL FORM

The viva-voce of the PhD Thesis submitted by shri Bhupendra Parmar (En-

rollment No. 129990911002) entitled Analysis and optimization of routing

techniques for wireless ad-hoc networks was conducted on .............................

(day and date) at Gujarat Technological University, Ahmedabad.

(Please tick any one of the following option)

� The performance of the candidate was satisfactory. We recommend

that he/she beawarded the PhD degree.

� Any further modifications in research work recommended by the panel

after 3 months from the date of first viva-voce upon request of the

Supervisor or request of Independent Research Scholar after which viva-

voce can be re-conducted by the same panel again.

(briefly specify the modifications suggested by the panel)

� The performance of the candidate was unsatisfactory. We recommend

that he/she should not be awarded the PhD degree.

(The panel must give justifications forrejecting the research work)

..................................................................... ......................................................................

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xi

ABSTRACT

Fixed wireless local area networks (WLANs) can be extended to mobile WLANs.

MANETs are such networks formed temporarily on an ad-hoc basis without fixed

infrastructure and centralized administration. As defined by IEEE 802.11 stan-

dards, the major difference between MANETs and WLAN is that MANET’s are

BSS (basic service set) without AP (Access Point) whereas WLANs are BSS with

an AP. Applications of MANET includes remote military and emergency opera-

tions where it is required to form the instantaneous network. In MANETs partici-

pating nodes acts as hop to forms multi-hop links between source and destination.

Design and deployment of MANETs are challenging due to issues like routing,

energy consumption, scalability, quality of services, available bandwidth, security

etc. The limited battery power of the node is one of the important issues in

MANET’s. The battery power of node can be saved if we reduce extra trans-

missions in the form of control messages or by regulating transmission power per

transmission based on criteria like distance.

Routing is challenging due to the mobility of nodes in MANETs. The process of

formation of end to end route and its maintenance is called routing. In MANETs,

the routing process is influenced by mobility, density and power limitations of

nodes in a network. There are three categories of routing protocols for MANETs,

reactive, proactive and hybrid. Reactive routing protocols also called on-demand

routing protocols. Reactive routing protocols find end to end rout when source

node has data packet for a particular destination. Examples of important reac-

tive routing protocols are Ad-hoc On-Demand Distance Vector (AODV) routing,

Dynamic Source routing (DSR) etc. Proactive routing protocols are those routing

protocols which find end to end routs in advance. All nodes in a network maintain

a routing table which consists ready to use routes to all other nodes in a network.

Examples of important proactive routing protocols are Destination Sequenced Dis-

tance Vector(DSDV) routing, Wireless Routing Protocol(WRP), Optimized Link

State(OLSR) routing etc. Hybrid routing protocol has characteristics of both

reactive and proactive routing protocols. Examples of hybrid routing protocols

are Core-Extraction Distributed ad hoc Routing (CEDAR), Zone Routing Proto-

xii

col(ZRP) etc.

The aim of this thesis is to optimize routing in MANETs. We have proposed GPS

aided power efficient routing technique which can find the shortest end to end

route in terms of distance and number of nodes with mobility considerations. In

the proposed technique, GPS locations of transmitter and receiver nodes are used

to calculate the distance between them and the dynamic value of transmission

power is then calculated based on distance. Provided GPS location of destination

node, a source node can find the shortest end to end route with minimum power

consumption using the proposed technique. To check suitability and efficiency

of proposed routing technique we have modified well known Ad-hoc On-demand

Distance Vector (AODV) routing dynamic source routing (DSR) protocol. The

routing table of both protocols consists GPS locations of various destinations and

source node itself. Location information is gathered and updated during network

initialization and data exchanges. Nodes can also share location information pe-

riodic beacons. If the GPS location of the destination node is not available then

instead of global flooding, controlled flooding is used for route discovery.

xiii

ACKNOWLEDGMENT

I thank almighty for showering me with courage, confidence, and support. PhD is

a long journey with many ups and downs. Without blessings from the GOD, it is

not possible to finish this journey.

I thank my parents, my wife, my cute son, and daughter for supporting me

throughout the duration of this work.

I thank my supervisor Dr. Kishor G. Maradia for constantly prompting me to do

something new. He is my mentor and guide during my masters at LDCE and now

as a PhD guide. I would like to say without his kind support and mental support

this work was not achievable.

I thanks my colleagues, specifically I would like to name Prof. S. H. Sangada,

Prof. R. M. Patel, Prof. V. J. Patel, and Prof. V. J. Chavda. Special thanks to

Prof. T. P. Gundrania who kept me confident and motivational towards my work.

xiv

Contents

Declaration ii

Abstract xii

Acknowledgment xiv

List of Abbreviations xx

List of Figures xxiii

List of Tables xxiv

1 Introduction 1

1.1 Scope of the Study and Problem Statement . . . . . . . . . . . . . 2

1.1.1 Aims and objectives . . . . . . . . . . . . . . . . . . . . . . 3

1.2 Original contribution by the thesis . . . . . . . . . . . . . . . . . . 4

1.3 Research Methodology . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.4 Organization of thesis . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 Mobile Ad-hoc networks 6

2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.2 History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

xv

CONTENTS

2.3 Ad-Hoc versus cellular networks . . . . . . . . . . . . . . . . . . . . 7

2.4 Network architecture - MANETs . . . . . . . . . . . . . . . . . . . . 9

2.5 Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.6 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.7 Design issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.8 Deployment Considerations . . . . . . . . . . . . . . . . . . . . . . 14

2.9 Open source simulators for MANETs . . . . . . . . . . . . . . . . . 15

3 Routing Protocols for MANET’s 19

3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.2 Responsibilities of routing protocol . . . . . . . . . . . . . . . . . . 19

3.3 Design Issues of routing protocol . . . . . . . . . . . . . . . . . . . 20

3.4 Properties of routing protocol . . . . . . . . . . . . . . . . . . . . . 22

3.4.1 Why Routing in MANET is Different? . . . . . . . . . . . . 23

3.5 Routing Protocols: Classification . . . . . . . . . . . . . . . . . . . 24

3.5.1 Table Driven (Proactive) . . . . . . . . . . . . . . . . . . . . 24

3.5.2 On Demand (Reactive) . . . . . . . . . . . . . . . . . . . . . 25

3.5.3 Hybrid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

3.5.4 classification based on method of packet delivery . . . . . . . 26

3.6 Important MANTEs Routing Protocols . . . . . . . . . . . . . . . . 27

3.7 Issues with existing routing protocols . . . . . . . . . . . . . . . . . 35

3.8 Possible aids to improve routing . . . . . . . . . . . . . . . . . . . . 35

xvi

CONTENTS

4 Dynamic Power control 38

4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

4.2 Energy Conservation Approaches . . . . . . . . . . . . . . . . . . . 39

4.3 Power control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

4.3.1 Effects of low and high transmission power control . . . . . . 43

4.3.2 Effects of fixed and variable transmission power . . . . . . . 43

4.4 Examples of power control protocols . . . . . . . . . . . . . . . . . 44

4.5 Power management . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

4.5.1 Importance of power management in ad hoc networks . . . . 46

4.5.2 Examples of power management protocols . . . . . . . . . . 47

5 GPS aided routing 50

5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

5.2 Position based routing . . . . . . . . . . . . . . . . . . . . . . . . . 51

5.2.1 Literature Survey . . . . . . . . . . . . . . . . . . . . . . . . 52

5.2.2 Open issues and challenges . . . . . . . . . . . . . . . . . . . 54

5.3 GPS Aided Routing - Proposed Technique . . . . . . . . . . . . . . 57

5.4 GPS aided AODV . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.4.1 Related work . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.4.2 Conventional AODV versus GPS aided AODV . . . . . . . . 67

5.4.3 Working of GPS aided AODV . . . . . . . . . . . . . . . . . 68

5.5 GPS aided DSR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

xvii

CONTENTS

5.5.1 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . 72

5.5.2 DSR versus GPS aided DSR . . . . . . . . . . . . . . . . . . 74

5.5.3 Working of GPS aided DSR . . . . . . . . . . . . . . . . . . 74

6 Simulation & Performance Analysis 79

6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

6.2 Simulation Parameters . . . . . . . . . . . . . . . . . . . . . . . . . 79

6.3 Simulation metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

6.4 GPS Aided AODV . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

6.4.1 Power Consumption V/S number of nodes . . . . . . . . . . 83

6.4.2 Energy Consumption V/S number of nodes . . . . . . . . . . 84

6.4.3 End to End delay V/S number of nodes . . . . . . . . . . . 84

6.4.4 Normalized Routing Load V/S number of nodes . . . . . . . 85

6.4.5 Packet Delivery Ratio V/S number of nodes . . . . . . . . . 86

6.4.6 Throughput V/S number of nodes . . . . . . . . . . . . . . . 86

6.4.7 Result Summary - AODV . . . . . . . . . . . . . . . . . . . 87

6.5 GPS Aided DSR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

6.5.1 Power Consumption V/S number of nodes . . . . . . . . . . 88

6.5.2 Energy Consumption V/S number of nodes . . . . . . . . . . 89

6.5.3 End to End delay V/S number of nodes . . . . . . . . . . . 90

6.5.4 Normalized Routing Load V/S number of nodes . . . . . . . 90

6.5.5 Packet Delivery Ratio V/S number of nodes . . . . . . . . . 91

xviii

CONTENTS

6.5.6 Throughput V/S number of nodes . . . . . . . . . . . . . . . 91

6.5.7 Result Summary - DSR . . . . . . . . . . . . . . . . . . . . 93

6.6 GPS aided AODV v/s GPS aided DSR . . . . . . . . . . . . . . . . 93

6.6.1 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Conclusion 95

Future Work 96

List of References 97

Publications 108

Appendix A 109

xix

List of Abbreviation

IEEE Institute of Electrical and Electronics Engineers

CBR Constant Bit Rate

AODV Ad-hoc On Demand Distance Vector

DSDV Destination Sequenced Distance Vector

DSR Dynamic Source Routing

GPS Global Positioning System

LEACH Low Energy Adaptive Clustering Hierarchy

MANET Mobile Ad hoc Network

NRL Normalized Routing Load

OSI Open System Interconnection

PDF Packet Delivery Fraction

PDR Packet Delivery Ratio

RERR Route Error Messages

RREP Route Reply Messages

RREQ Route Request Messages

TORA Temporally Ordered Routing Algorithm

UDP User Datagram Protocol

WRP Wireless Routing Protocol

WSN Wireless Sensor Network

IETF Internet Engineering Task Force

WLAN Wireless Local Area Networks

IP Internet Protocol

TCP Transmission Control Protocol

OLSR Optimized Link State Routing

EED End to End Delay

LAR Location-Aided Routing

xx

CONTENTS

EE Energy Efficiency

EPAR efficient power-aware routing

MAC Media Access Control

LEAR Localized Energy Aware Routing

FAR Flow Augmentation Routing

MER Minimum Energy Routing

CMMBCR Conditional Maxmin Battery Capacity Routing

REAR Retransmission Energy Aware Routing

GAF Geographic Adaptive Fidelity

PEN Prototype Embedded Network

COMPOW Smallest Common Power Routing

xxi

List of Figures

2.1 Ad-Hoc and cellular networks . . . . . . . . . . . . . . . . . . . . . 8

2.2 IEEE 802.11 Basic Service Set (BSS) . . . . . . . . . . . . . . . . . 9

2.3 Example of MANET . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.4 MANET with three nodes . . . . . . . . . . . . . . . . . . . . . . . 10

3.1 Classification of MANETs Routing Protocols . . . . . . . . . . . . 25

3.2 Classification based on the method of packet delivery . . . . . . . . 26

3.3 (a) Route discovery process (b) Route reply process . . . . . . . . . 29

3.4 (a) Route discovery process (b) Route reply process . . . . . . . . . 31

4.1 Classification based on the method of energy saving approach . . . 40

4.2 Layers in network reference model . . . . . . . . . . . . . . . . . . . 41

5.1 Path setup process . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

5.2 Route maintenance process . . . . . . . . . . . . . . . . . . . . . . . 60

5.3 Distance calculation between nodes . . . . . . . . . . . . . . . . . . 61

5.4 Relative movements of nodes . . . . . . . . . . . . . . . . . . . . . . 62

5.5 RREQ Packet Format . . . . . . . . . . . . . . . . . . . . . . . . . 68

5.6 RREP Packet Format . . . . . . . . . . . . . . . . . . . . . . . . . . 68

5.7 AODV - Route formation process . . . . . . . . . . . . . . . . . . . 69

xxii

LIST OF FIGURES

5.8 AODV - Route setup process . . . . . . . . . . . . . . . . . . . . . 70

5.9 AODV - Route maintenance process . . . . . . . . . . . . . . . . . . 71

5.10 Packet flow - Basic DSR . . . . . . . . . . . . . . . . . . . . . . . . 72

5.11 Forwarding data packet . . . . . . . . . . . . . . . . . . . . . . . . . 76

5.12 DSR - Route setup process . . . . . . . . . . . . . . . . . . . . . . . 77

5.13 DSR - Route Discovery process . . . . . . . . . . . . . . . . . . . . 78

6.1 Power Consumption v/s increasing nodes . . . . . . . . . . . . . . . 83

6.2 Energy Consumption (Joules) v/s increasing nodes . . . . . . . . . 84

6.3 End to End delay v/s increasing nodes . . . . . . . . . . . . . . . . 85

6.4 Normalized Routing Load v/s increasing nodes . . . . . . . . . . . . 86

6.5 Packet Delivery Ratio v/s increasing nodes . . . . . . . . . . . . . . 87

6.6 Throughput v/s increasing nodes . . . . . . . . . . . . . . . . . . . 88

6.7 Power Consumption v/s increasing nodes . . . . . . . . . . . . . . . 89

6.8 Energy Consumption (Joules) v/s increasing nodes . . . . . . . . . 89

6.9 End to End delay v/s increasing nodes . . . . . . . . . . . . . . . . 90

6.10 Normalized Routing Load v/s increasing nodes . . . . . . . . . . . . 91

6.11 Packet Delivery Ratio v/s increasing nodes . . . . . . . . . . . . . . 92

6.12 Throughput v/s increasing nodes . . . . . . . . . . . . . . . . . . . 92

xxiii

List of Tables

2.1 Ad-hoc networks versus cellular networks . . . . . . . . . . . . . . . 8

6.1 Simulation Parameters . . . . . . . . . . . . . . . . . . . . . . . . . 80

6.2 GPS aided AODV Versus AODV . . . . . . . . . . . . . . . . . . . 87

6.3 GPS aided DSR Versus DSR . . . . . . . . . . . . . . . . . . . . . . 93

6.4 GPS aided AODV Versus GPS aided DSR . . . . . . . . . . . . . . 93

6.5 Energy Consumption Proposed versus other routing protocols . . . 94

xxiv

CHAPTER 1

Introduction

Wireless networks are an essential part of modern communication where it pro-

vides complete end to end wireless connectivity. Compared to wired networks,

wireless networks are best in terms of ease of use, cost of deployment and many

others. There are two types of wireless networks: infrastructure, where a path is

established using a base station; and non-infrastructure, where there is no base

station and the nodes can move freely and organize themselves arbitrarily. An

example of a non-infrastructure network is a Mobile Ad Hoc Network (MANET),

which has many applications, including both personal and military use.

MANETs have been a key area of research for both the academic and industrial

sectors due to its applicability in the modern era of advanced communication. Ad

hoc networks have become increasingly common since the 1990s, with more and

more applications being developed. Nowadays, versions of MANETs like sensor

networks finds major parts in smart city developments. The major challenge to

MANETs is the absence of fixed infrastructure and centralized administration.

Participating nodes (sensors in case of sensor networks) organize themselves to

form a fully functional network wherein they (participating nodes) acts as relaying

hops to form end to end communication links. Routing, energy conservations,

security, quality of services, are other major issues in MANTEs. Future aspects

of MANETs and its special characteristics are the motivational forces for carrying

out this research.

1

CHAPTER 1. INTRODUCTION

1.1 Scope of the Study and Problem Statement

Characteristics like infrastructure less, self-organizing and distributed network

make MANETs a perfect candidate for networking during remote military and

emergency operations. Participating nodes act as intermediate hops to form end

to end links. Since the nodes have random mobility and limited battery power, the

lifetime of link formed very short and leads to frequent link breaks. Frequent link

breaks increases control overhead because every link break leads to fresh route

discovery. Frequent route discoveries also increase the number of transmissions

and therefore consumption of battery power. In this research, we have proposed

unique algorithm which intends to find a route with the shortest length and mini-

mum intermediate hops. Power transmission is dynamic and based on distance to

receiving node. We have used GPS locations of the source and destination nodes

to find the shortest end to end distance and value of transmission power requires

between transmitting and receiving node. We have also considered the mobility of

nodes while selecting a particular node as intermediate hope. If a node is moving

in opposite direction to the transmigrating node then it can not be selected as

next node in a route.

To optimize routing in MANETs, We have proposed GPS aided routing technique

which can find the shortest end to end route in terms of distance and number of

nodes with mobility considerations. In the proposed technique, GPS locations of

transmitter and receiver nodes are used to calculate the distance between them

and the dynamic value of transmission power is then calculated based on distance.

Provided GPS location of the destination node, a source node can find the shortest

end to end route with minimum power consumption using the proposed technique.

To check suitability and efficiency of proposed routing technique we have modi-

fied well known Ad-hoc On-demand Distance Vector (AODV) routing dynamic

source routing (DSR) protocol. The routing table of both protocols consists GPS

locations of various destinations and source node itself. Location information is

gathered and updated during network initialization and data exchanges. Nodes

can also share location information periodic beacons. If the GPS location of the

2


destination node is not available then instead of global flooding, controlled flooding

is used for route discovery.

1.1.1 Aims and objectives

The aim of this research is to optimize routing in MANETs. It is anticipated that

end to end rout with the shortest distance improves routing efficiency in terms of

end to end delay and dynamic power control increases network lifetime. The aim

and objective of research are,

• Literature survey on MANETs and its routing protocols to find the research

gap and to define problem statement.

• Analytical study of routing protocols available for MANETs to select most

suitable routing protocols for further optimization.

• Simulation of selected routing protocols with different parameters and sce-

narios.

• To find and formulate method which can find the shortest end to end path

and dynamically regulate transmission power of transmitting node based on

distance to receiving node.

• Simulation of the proposed optimization scheme with presently available

routing protocols(AODV and DSR).

• Comparative analysis of proposed optimization with traditional AODV and

DSR routing protocols.

• Developing sequence of routing steps for routing node to route a packet with

minimum transmission power while selecting the nearest intermediate node

in a path to the destination node.

• Developing GPS based power efficient routing technique and implementation

with AODV and DSR.

3


• Comparison of simulation results and suitability check of proposed optimiza-

tion efficiency of GPS aided routing for future implementations.

1.2 Original contribution by the thesis

GPS aided routing is discussed in this thesis. we have proposed the GPS based

algorithm to find minimum transmission power based on the distance between two

nodes. This algorithm uses Haversine formula to find the distance between two

nodes based on their GPS information. Key features of GPS aided routing are as

follows,

• Finds the shortest path to the destination in terms of path length.

• Select next node based on mobility information.

• Calculates the value of transmission power based on transmission distance.

• Uses the calculated value of transmission power to transmit a packet to next

node.

• For AODV it stores the nearest node to the destination as the next node in

a path to the destination, with a value of required transmission power.

• In DSR, it finds the shortest route to the destination using GPS location

of possible intermediate nodes from route cache and put it into the packet

header. Value of transmission power is calculated at a local level.

• DSR all node keep updates of neighboring nodes in the form of distance and

required power transmission.

1.3 Research Methodology

We have studied and carried out literature survey related available routing pro-

tocols in MANETs. We have done a comparative analysis of important routing

4


protocols to find out research gap, to define problem statement and objective of the

research. Initially, we have used ns2.34 simulation tool for comparative analysis of

important routing protocols in MANETs, later on for simulation and comparative

analysis of proposed technique we have used ns3.25. We have selected and modify

most suitable routing protocols available in the literature to check the suitability

of algorithm proposed in the thesis. we have done a comparative analysis of trace

obtained from simulation of conventional routing protocols and modified routing

protocols with different parameters and scenarios. This research is qualitative as

GPS aided power efficient routing technique is able to find the shortest source to

destination routs with comparatively less end to end delay and control overhead.

Due to the dynamic value of power transmission in GPS aided routing, battery

power consumption is greatly reduced. This research is experimental since we

have created different scenarios in ns3.25 and tested the proposed routing tech-

nique with different parameters and network scenarios.

1.4 Organization of thesis

The rest of this thesis is organized as follows: chapter 2 introduces wireless and mo-

bile ad hoc networks (MANETs) with focus on MANETs features, characteristics,

applications, and deployment considerations. Chapter 3 introduces the concepts

routing, routing issues, categories of routing protocols and some important rout-

ing protocols. This chapter describes AODV and DSR routing protocols in detail

with their limitations and available optimizations. Chapter 4 describes position

based routing and mainly focuses on proposed GPS aided routing, haversine for-

mula and power model used for proposed research. The prime aim of chapter 4

is to discuss GPS aided AODV and DSR protocols optimizations with detailed

literature survey. Chapter 5: presents the methodology, simulation parameters

performance evaluation metrics, simulation environment, results of the simulation

and comparative result analysis. Chapter 7: provides a summarize and concludes

the thesis with highlights on further study and opportunities in the area under

discussion.

5

CHAPTER 2

Mobile Ad-hoc networks

2.1 Introduction

Wireless Local Area Networks (WLANs) can be extended to mobile WLANs. Mo-

bile Ad-hoc Networks (MANETs) are such networks formed temporarily on a ad-

hoc basis without fixed infrastructure and centralized administration. MANETs

are very useful in remote military and emergency operations. In this type of

networks, participating nodes acts as hop to form multi-hop link between source

and destination. As defined by IEEE 802.11 standards, the major difference be-

tween MANETs and WLAN is that MANETs are BSS (basic service set) without

AP (Access Point) whereas WLANs are BSS with AP. Design and deployment of

MANET ′s are challenging due to issues like routing, energy consumption, scala-

bility, quality of services, available bandwidth, security etc. This chapter primarily

focuses on design and deployment issues of MANETs.

2.2 History

Ad hoc networking is multi-hop relaying of the data packets from source to desti-

nation. In history, people use to send message from one place to another by fire

lighting at top of hills visible from a long distance or shouting by men positioned

on tall structures. During the last century with the advent of wireless radio, the

world has witnessed tremendous growth in the area of relay communication. In

1980, the requirement of open standard forced to form a working group within

the Internet Engineering Task Force (IETF). The IETF formed Mobile Ad-hoc

6

CHAPTER 2. MOBILE AD-HOC NETWORKS

Networks (MANETs) working group [1] [2] to standardized the protocol and func-

tional specifications of wireless ad-hoc networks. The goal of MANTETs working

group is to provide improved standardized routing functionality to support self-

organizing mobile networking infrastructure. IETF focused on what we call pure

and general purpose MANETs, pure means without infrastructure and central

administration and general purpose means networks are not designed with any

specific application. The research by IETF also focuses on enhancing and extend-

ing the IP-layer routing and forwarding functionalities in order to support internet

services in a network without any infrastructure. Network layer routing protocols

are still Issue because Internet routing protocols developed for wired networks are

clearly not suitable for the unpredictable and dynamic nature of MANET topol-

ogy [3]. In 1994, Swedish company Ericsson proposed a short range, low power,

less complex and inexpensive wireless communication equipment called Bluetooth

to connect independent devices. Bluetooth standardizes the single hop point to

point wireless link that can be used for voice or data exchanges. Group of nodes

can form piconet single hop network in a limited geographical region. multiple

piconets can form Scatternet which requires multihop routing protocol. Later on,

IEEE has defined the specifications for a wireless LAN, called IEEE 802.11. It

covers Physical and Data link layer specifications and standards.

2.3 Ad-Hoc versus cellular networks

Main Difference between ad-hoc and cellular networks is that later is infrastructure

dependent network whereas former is infrastructure less network. Other impor-

tant difference is that cellular networks are coordinated and controlled centrally

whereas ad hoc networks are self-organizing networks without any centralized ad-

ministration. In cellular networks nodes in a specific geographical area called cell

are connected to the base station (BS) for the end to end communication as shown

in figure 2.1. In ad-hoc networks routing and resource management are done in a

distributed manner where nodes in a network co-ordinate to form communication

links with each other. A node in ad-hoc network simultaneously acts as host and

7


hop. Ad hoc networks are more complex than cellular networks in general. The

architecture of Cellular network is hierarchical whereas that of ad hoc network is

distributed. Table 6.3 outlines the principal characteristics of both ad hoc and

cellular networks.

Figure 2.1: Ad-Hoc and cellular networks

Sr.No.

Ad-Hoc Networks Cellular Networks

1 Without fixed Infrastructure Fixed infrastructure2 Multi-hop links Single-hop links3 Shared radio channel Guaranteed bandwidth4 Distributed routing Centralized routing5 Routing aims to find paths with

minimum overheads and quick re-configuration of broken paths

Routing and call admission aim tomaximize call acceptance ratio andminimize the call drop ratio

6 Frequent path breaks Seamless connectivity7 Packet-switched Circuit-switched8 Quick and cost-effective deployment High cost and time of deployment9 Difficult time synchronization,

which consumes bandwidthEasier to achieve time synchroniza-tion

10 Self-organization and maintenanceproperties built into the network

High network maintenance cost

Table 2.1: Ad-hoc networks versus cellular networks

8


2.4 Network architecture - MANETs

MANETs are kind of WLANs which does not need any fixed infrastructure. IEEE

802.11 defines the basic service set (BSS) as the building blocks of a wireless LAN.

A BSS consist of stationary or mobile wireless nodes and an optional central BS,

known as the access point (AP) as shown in figure 2.2. The BSS without an

AP is a stand-alone network and cannot communicate with other BSSs. This

type of stand-alone network architecture is called an ad hoc architecture. In this

architecture, nodes can form a network without the need of an AP and central

administration. Nodes can locate one another and agree to be part of a BSS.

Participating nodes communicate directly with each other forming multi-hop links.

Fully functional MANETs consist set of mobile nodes connected to each other via

multihop links as shown in figure 2.3.

Figure 2.2: IEEE 802.11 Basic Service Set (BSS)

In the figure 2.4 a sample model of MANET is presented consisting of three

nodes(A, B and C). Dotted circles mark the radio transmission ranges of the

nodes. Node A and node B are within the transmission ranges of each other and

are called neighbors of the other. Similarly, B and C are within the transmission

ranges of each other. Here A and C are not in the direct transmission range of

each other. Here neighbors can communicate directly to each other and no routing

is required. But, if node A (source node) and C (destination node) want to com-

municate with each other, it is only possible through node B (intermediate node).

Node B works as a relaying node between node A and C. In this case, some sort

9


Figure 2.3: Example of MANET

of routing mechanism is required to form end to end link between source and des-

tination. Routing protocol makes Node A know that node C is reachable through

B, and it communicates with node B first to form a final link with node C which

is transmission range of node B. Routing becomes complicated if more nodes are

involved due to multiple routes to destination available with different constraints.

Figure 2.4: MANET with three nodes

2.5 Characteristics

MANET’s are autonomous, distributed and infrastructure less networks. In MANET

a node acts as host cum router and message between source and destination is

10


transmitted by multi-hop relaying. A network topology is dynamic due to the

random mobility of nodes, a node can leave or enter the network any time. The

nodes are battery operated with limited memory and hardware. The reliabil-

ity, efficiency, stability, and capacity of wireless links depends on the density of

nodes and network geography. Important features of MANETs are discussed in [4].

Compared to cellular networks, MANETs has the following distinct features,

• Multi-Hopping: End to end communication in MANETs is carried out through

multi-hop links formed by participating nodes. Transmitting node form mul-

tihop link consisting available nodes to participate in the active communi-

cation.

• Dynamic Topology: Mobility of nodes in MANETs is random and there is

no fixed network topology and routes to various destinations. Due to this,

there are chances of frequent rout breaks which results in high overhead due

to fresh rout discoveries.

• Energy Conservation: Nodes are battery operated. Due to the fact that

batteries have a limited life, if node remains active for unusual activities

its battery may die early. To extend the battery life, sophisticated energy

conserving algorithms are required.

• Self-Organization: Apart from wired and cellular networks, MANETs are

had special feature where there is no fixed infrastructure and centralized

administration. Nodes are designed to self-organize themselves to form an

active network without the external aide. This feature of MANETs is very

useful in emergency and military applications where instant deployment of

fully functional network is required.

2.6 Applications

Due to the quick and economic deployment of wireless ad-hoc networks, it finds ap-

plications in many areas like military applications, collaborative and distributed

11


computing, emergency operations, wireless mesh networks, wireless sensor net-

works, and hybrid wireless networks. Here we discuss some important applications

of wireless ad-hoc networks in brief.

• Military applications: In the absence of infrastructure cellular network in

enemy areas, ad-hoc networks can be very useful in establishing temporary

communication among a group of soldiers for tactical operations. Ad-hoc

networks can provide reliable and secure communication with battery op-

erated light equipment. Such GPS equipped equipment can be used for

tracking and coordination purpose also.

• Emergency applications: Ad-hoc networks can be very useful in emergency

operations such as search and rescue, crowd control, and commando opera-

tions. Due to self-organizing nature of ad hoc networks, it can be deployed

in emergency areas quickly. For these type of operations ad hoc networks

should be distributed and scalable to large area and number of nodes.

• Sensor Networks: Wireless sensor networks are a special category of ad-hoc

networks. Sensor networks are wireless ad-hoc networks consist of sensors

as a node which deployed for special application purpose. Sensor networks

find many applications in projects like smart cities, agriculture etc. These

sensors in a network communicate, coordinate and act based on a specific

task.

2.7 Design issues

This section discusses the major issues and challenges that need to address while

designing and deploying wireless ad-hoc networks. The major issues that affect the

design, deployment, and performance of ad-hoc networks are discussed as follows.

• Media Access Scheme: Medium access scheme refers to a method by which

nodes in a network shares a channel to send and receive data. In MANET’s

many mobile nodes share the channel at a time, the MAC (Media Access

12


Control) protocol must allow the access to media in a distributed fashion.

MAC protocol needs to take care of collisions with neighboring nodes while

allowing a node to access the media. Major challenges for MAC protocol are

mobility of nodes, hidden and exposed terminals.

• Routing: Routing is the process of formation of multi-hop path from source

to destination. Compared to wired and fixed-topology networks where and

to end routes are fixed, routing in MANETs is different because of mobile

nodes and dynamic topology. A major challenge for routing protocol for

MANETs is the dynamic topology of network and random motion of nodes.

The routs are getting older frequently due to the mobility of intermediate

nodes. This leads frequent route discoveries and large control overhead.

Routing also needs to take care of available power and bandwidth while

selecting particular node as the next hop in the path. It is also important

to repair broken paths with minimum delay and control overhead. Routing

protocol for MANET should find the end to end route taking a minimum

amount of processing time and resources.

• Security: Security of data is one of major challenge since wireless media is

used to send and receive data between two nodes. The wireless signal can

be easily intercepted and may be used for false purpose easily. Appropriate

data coding and encoding technique must be incorporated in order to ensure

safe transmission of data between transmitter and receiver. Apart from this

authenticity of nodes involved is required to be taken care of.

• Energy Management: Energy management is the process of controlling uses

of energy by nodes in a network to increase the network lifetime. Since nodes

in MANETs are battery operated, the energy is always an issue. If node con-

stantly involves as hop, energy consumption in relaying packet affects the

power availability to perform other functions. Power saving mechanism must

be adopted to save battery like sleeping mode while there is no function to

perform and variable transmission power based on criteria’s like distance. en-

ergy management also includes the techniques to reduce power consumption

by radio frequency (Rf) module of a node. This can be done by control-

13


ling factors like state of operation, transmission power, and quality of RF

circuitry. The state of operation refers to a mode of operations like sleep,

transmit and receive. Transmission power is calculated by the average dis-

tance to receiver nodes in a network. RF circuitry design must ensure that

it consumes minimum power during operation and remains in sleep mode

for rest of time. Transmission power consumption is also affected by kind of

routing protocol at the network layer and MAC protocol at data link layer

is employed. Transmission power management at MAC protocol increases

energy and bandwidth efficiency of nodes and reduces interference.

• Addressing: Due to dynamic topology of MANETs, auto-configuration of

addresses is required to prevent duplication of addresses. When a particular

node enters the network for a limited amount of time, the address assigned

must be unique in a network.

• Scalability: Scalability refers to the number of nodes can be accommodated

in a network without affecting the performance of network as a whole. Tra-

ditional applications such as military and emergency operations do not need

to scale to large size. Large size ad hoc networks may not feasible because

of problems like routing.

2.8 Deployment Considerations

Deployment of MANET is different compared to wired networks. Wired networks

require complex planning before deployment. Whereas deployment of MANETs

has the following key advantages over wired networks,

• Low-cost deployment: Since the end to end links are formed by intermedi-

ate nodes, and the communication is hop to hop, the deployment cost of

MANETs is lower compared to wired networks. MANETs has the ability to

reconfigure automatically, the maintenance cost is comparatively less.

• Short deployment time: The deployment time is considerably less because

14


MANETs are self-configured, infrastructure less networks. So it does not

require to lay typical hardware to form a fully functional network.

• Incremental deployment: MANETs are capable of working with few nodes

initially and more nodes can be added gradually. Therefore in emergency

situations network can add more nodes to existing functional network.

• Reconfigurability: Reconfiguration of MANETs is easy and cost less com-

pared to wired networks. This is because MANETs needs to replace fixed

relay point if any in later stages of time. It actually depends on the type of

application for which MANET is deployed.

• Network Area: MANETs are intended to cover limited geographical area

as it can be seen from its applications. Since end to end communication is

carried out hop to hop, the coverage area of nodes is important factor which

limits the network coverage area.

2.9 Open source simulators for MANETs

Establishing and implementation of MANETs in real time is difficult and not

feasible. Deployment of fully operational MANETs needs synchronization and

knowledge of all network components and layers. To verify and test functionality is

possible using simulation where the exact scenario is created using various models.

Variety of open source network simulators are available for research and education

purpose. Important simulation software being used and discussed in the literature

are GloMoSim [5] [6], OMNeT++ [7] [8], OPNET [9], NS-2 [10] and NS-3 [11] [12].

• GloMoSim: GLOMOSIM [5] [6] is a global mobile information system

simulator and satellite network simulation environment. It is a popular

simulation tool which is free for education, research and developed from

springer paper. It can be used to simulate wired as well as different wireless

communication networks like mobile Ad-hoc networks and wireless sensor

15


networks. GLOMOSIM uses parallel discrete event simulation provided by

C based simulation language. Important features of GloMoSim are [13],

– Contains modular and extensible library for network models.

– Supports protocols used in only wireless networks.

– Platform-independent tool.

– Uses Customizable GUI.

– Uses interfaces to support interoperability between OPNET and Glo-

moSim models with the help of HLA and RPR-FOM.

– Supports Parallelization and built according to the OSI layered ap-

proach.

– Can be used for real-time simulation of wireless networks.

• OMNet++: OMNet++(Objective Modular Network Testbed in C++) is

modular, component-based discrete event simulator based on C++ simula-

tion library and framework. It is primarily used for building network simu-

lators that include wired and wireless communication networks, on-chip net-

works, queuing networks etc. It has domain-specific functionality support for

sensor networks, wireless ad-hoc networks, internet protocols, performance

modeling, and photonic networks provided by model frameworks which is

developed as independent projects. OMNeT++ offers an eclipse-based IDE,

a graphical runtime environment, and a host of other tools. There are ex-

tensions for real-time simulation, network emulation, database integration,

and several other functions.

• OPNET: OPNET Network simulator used to simulate and analyze the be-

havior and performance of different wired and wireless networks. The main

difference OPNET and other network Simulators lies in its power and ver-

satility. It is an open and free software for education research. It provides a

large number of project scenarios for network simulations and allows prac-

tical simulation of networks with performance data collection and display

modules. It has high fidelity discrete event simulation models for modern

technologies like IPv6, LTE, MPLS, UMTS, and 802.16(WiMax).

16


• NS-2: NS-2 (Network Simulator 2) is an object-orientated discrete event

simulator. NS2 is an open-source simulation tool that runs on Linux. It

aims at networking research and provides substantial support for simula-

tion of routing, multicast protocols and IP protocols, such as UDP, TCP,

RTP, and SRM over wired and wireless (local and satellite) networks. It

has many advantages that make it a useful tool, such as support for mul-

tiple protocols and the capability of graphically detailing network traffic.

Additionally, it supports several algorithms in routing and queuing. LAN

routing and broadcasts are part of routing algorithms. Queuing algorithms

include fair queuing, deficit round-robin and FIFO. Currently, NS2 devel-

opment by VINT group is supported through Defense Advanced Research

Projects Agency (DARPA) with SAMAN and through NSF with CONSER,

both in collaboration with other researchers including ACIRI. NS2 is avail-

able on several platforms such as FreeBSD, Linux, SunOS, and Solaris. NS2

also builds and runs under Windows.

• NS-3: ns-3 is a discrete-event, packet-level network simulator for network-

ing research and education. ns-3 is built as a system of software libraries

that work together. User programs can be written that links with these

libraries. User programs are written in either the C++ or Python pro-

gramming languages. Users of ns-3 can construct simulations of computer

networks using models of traffic generators, protocols such as TCP/IP, and

devices and channels such as Wi-Fi and LTE, and analyze or visualize the

results. Simulation plays a vital role in the research and education process,

because of the ability for simulations to obtain reproducible results, scale

to large networks, and study systems that have not yet been implemented.

A particular emphasis in ns-3 is the high degree of realism in the models

and integration of the tool with VM environments and test beds. Very large

scale simulations are possible using ns-3. Ns-3 has been in development since

2005 and its latest update is ns-3.29 released in September 2018. Important

features of ns-3 are,

– Scalability: In ns-3 packets can have virtual zero bytes which reduces

17


memory allocation during simulation. Nodes have additional features

like IPv4 stack and mobility models are optional.

– Cross-layer: Small units of information can be added to packets. It

allows tracing of events across multiple layers.

– Real-world integration: Packets can be saved to PCAP file format which

can be read by many openly available tools. Various simulation events

are synchronized to real clock. It can run a linux kernel TCP/IP stack

under simulation.

18

CHAPTER 3

Routing Protocols for MANET’s

3.1 Introduction

Routing is the process of delivering data packet from source to destination. It

is an important and challenging issue in MANET’s where hope to hope packet

delivery mechanism is accomplished and intermediate nodes act as hope. Due

to the mobility of nodes with different speed and direction routing is complex.

Energy, bandwidth, control overhead and node co-operation are other issues which

are to be taken into consideration while designing a routing protocol for MANET’s.

Most of the routing protocols proposed for MANET’s are inherited from wired

networks where characteristics of networks (fixed nodes) are far different form

MANTE’s. There are two broad categories of routing protocols for MANET’s

wise reactive and proactive. Reactive routing protocols are those routing protocols

which find routes from source to destination when there is data to be sent to

particular destination node.

3.2 Responsibilities of routing protocol

Routing protocol plays a major role in MANETs overall performs. Routing pro-

tocol establishes and maintains source to destination with following additional

responsibilities,

• Exchange of route information: To form end to end links nodes requires

knowledge regarding whereabouts of neighbors and other nodes in the net-

19

CHAPTER 3. ROUTING PROTOCOLS FOR MANET’S

work. For this, all nodes require to share information like position, mobility,

resource availability etc. This can be done using periodic beacons and hello

messages. Exchange of information should consume minimum network re-

sources without unnecessary increase in control overhead.

• Finding a feasible path to a destination based on criteria’s such as,

– A number of intermediate hops.

– Route length.

– Available Battery power/energy consumption.

– Lifetime of the wireless link.

• Gathering information about path breaks so that the route can be re-established

to maintain average end to end delay.

• Mending the broken paths expending minimum processing power and band-

width.

• Utilizing minimum bandwidth for management and control messages.

3.3 Design Issues of routing protocol

Routing protocols of MANETs have many design issues due to MANETS char-

acteristics like node mobility, power limitations of the node, hidden and exposed

terminal problem etc. Other issues to be taken into consideration are security,

quality of services, reliability, channel utilization. A brief discussion on various

issues is given below.

• Node Mobility: The major challenge that the routing protocol has to face

is highly dynamic network topology due to the mobility of nodes. Random

speed and direction of motion of nodes result in frequent breaks in pre-

considered network topologies and end to end paths.

20


• Power Limitations of Node: Nodes in MANETs are battery operated. The

number of transmission attempts consumes considerable battery power. the

routing protocol must account the available battery power of node while

selecting as an intermediate node in a path.

• Hidden and Exposed Terminal Problem: Hidden terminal problem refers

to a collision of packets due to simultaneous transmission from two nodes

which are not in the direct transmission range of each other but in the trans-

mission range of a receiver. The collision occurs when both nodes transmit

data without knowing each others status of the activity. Exposed terminal

problem refers to inability of the node to transmit because neighbor node

occupies the channel. Due to this an effective channel utilization is affected.

• Radio channel: Link capacity and link error probability have time-varying

characteristics in MANETs. This makes routing protocol to find alternate

good quality links continuously. This problem becomes more complex be-

cause of retransmissions due to collisions of data packets. Therefore routing

protocol must find an efficient route with less congestion.

• Bandwidth: Radio channel in a wireless network is band limited and there-

fore data rate offered is less compared to wired channels like an optical fiber.

The routing protocol must limit the generation of the control packet to save

bandwidth. It is possible when there is a limitation on sharing topological

information among the nodes.

• Security: Security is one of the important concern in wireless networks com-

pared to fixed networks. Wireless networks are more prone to physical

threats at the link level. The routing protocol must embed some sort of

encryption to data being transmitted to ensure secure transmission of data.

Without some form of network-level or link-layer security, a MANET routing

protocol is vulnerable to many forms of attack. It may be relatively simple

to snoop network traffic, replay transmissions, manipulate packet headers,

and redirect routing messages, within a wireless network without appropriate

security provisions.

21


3.4 Properties of routing protocol

Due to the nature of mobility of nodes in MANETs, routing protocol needs an intel-

ligent mechanism to deal with issues discussed so far. In order to work efficiently,

the routing protocol of MANETs should exhibit the following properties [2],

• Distributed routing: Routing should be distributed to reduce large control

overhead involved in centralized routing. Distributed routing has high fault

tolerance compared to centralized routing.

• Loop-free routing: Routing should be loop-free meaning that packet must

not be spinning around network for an undefined period of time. The routing

protocol must form unidirectional links to the destination.

• Load distribution: Routing protocol should adopt certain factors like traffic

distribution within network and node mobility while routing packets. Intel-

ligent load distribution increases efficient utilization of network resources.

• Demand-based operation: Instead of assuming a uniform traffic distribution

within the network, let the routing algorithm adapt to the traffic pattern on

a demand or need basis. If this is done intelligently, it can utilize network

energy and bandwidth resources more efficiently, at the cost of increased

route discovery delay.

• Proactive operation: The flip-side of demand-based operation. In certain

contexts, the additional latency demand-based operation incurs may be un-

acceptable. If bandwidth and energy resources permit, the proactive opera-

tion is desirable in these contexts.

• Security: Without some form of network-level or link-layer security, a MANET

routing protocol is vulnerable to many forms of attack. It may be relatively

simple to snoop network traffic, replay transmissions, manipulate packet

headers, and redirect routing messages, within a wireless network without

appropriate security provisions. While these concerns exist within wired

22


infrastructures and routing protocols as well, maintaining the physical secu-

rity of the transmission media is harder in practice with MANETs. Sufficient

security protection to prohibit disruption of modification of protocol opera-

tion is desired. This may be somewhat orthogonal to any particular routing

protocol approach, e.g. through the application of IP Security techniques.

• Sleep period operation: As a result of energy conservation, or some other

need to be inactive, nodes of a MANET may stop transmitting and/or re-

ceiving (even receiving requires power) for arbitrary time periods. A routing

protocol should be able to accommodate such sleep periods without overly

adverse consequences. This property may require close coupling with the

link-layer protocol through a standardized interface.

• Unidirectional link support: Bidirectional links are typically assumed in the

design of routing algorithms, and many algorithms are incapable of func-

tioning properly over unidirectional links. Nevertheless, unidirectional links

can and do occur in wireless networks. Oftentimes, a sufficient number of

duplex links exist so that usage of unidirectional links is of limited added

value. However, in situations where a pair of unidirectional links (in oppo-

site directions) form the only bidirectional connection between two ad hoc

regions, the ability to make use of them is valuable.

• Quality of Service (QoS): A routing protocol should be aware of Quality of

Service (QoS). It should know about the delay and throughput for the route

of a source–destination pair and must be able to verify its longevity so that

a real-time application may rely on it.

3.4.1 Why Routing in MANET is Different?

Following are some characteristics of MANETs which makes routing more chal-

lenging compared to routing in other networks,

• Host mobility:

23


– Link failure/repair due to mobility.

– The rate of link failure/repair is higher when nodes move fast.

• Distributed Environment:

– No centralized routing possible because of the highly dynamic nature

of the network.

• Route stability must be ensured despite mobility.

• Location dependent contentions.

• Error-prone and shared channel.

• Varying geographical area and terrain.

• No fixed topology.

3.5 Routing Protocols: Classification

MANETs routing protocols can be classified into several categories based on rout-

ing information and update mechanism as shown in figure 3.1. There are three

major categories wise table driven, on demand and hybrid. Table-driven and

on-demand routing protocols are also known as proactive and reactive routing

protocols respectively. This section describes all three categories in detail.

3.5.1 Table Driven (Proactive)

Table-driven routing protocol maintains a table consisting most appropriate path

to all other nodes in a network. Table-driven routing protocols also known as

proactive protocols which continuously learn the topology of the network by ex-

changing topological information among the network nodes. The main concern

regarding using a proactive routing protocol is: if the network topology changes

too frequently, the cost of maintaining the network might be very high. Moreover,

if the network activity is low, the information about the actual topology might

24


MANETsRouting

Protocols

Table Driven(Proactive)

Examples:DSDVWRPOLSR

On Demand(Reactive)

Examples:DSR

AODVLAR

Hybrid

Examples:CEDAR

ZRPZHLS

Figure 3.1: Classification of MANETs Routing Protocols

even not be used and, in such a case, the investment with such limited transmission

ranges and energies is lost, which might result in a shorter lifetime of the network

than that is expected. Important table-driven routing protocols are DSDV, WRP,

OLSR etc.

3.5.2 On Demand (Reactive)

On-demand routing protocols executes path finding process and exchange route

information when source node has data packet for the destination node. In this

category one’s route is identified all packets follow the same route until route break

due to the mobility of intermediate nodes. Reactive routing protocols omits the

need to maintain a routing table and there is no need to exchange information

required to update tables. They do not need periodic transmission of topological

information of the network; hence, they primarily seem to be resource-conserving

protocols. Important on-demand routing protocols are AODV, DSR, LAR etc.

25


MANETs Routing Proto-cols based on method

of packet delivery

Unicast Routing Protocols Multicast Rout-ing Protocols

Tree-based mul-ticast protocol

Mesh-based mul-ticast protocol

Figure 3.2: Classification based on the method of packet delivery

3.5.3 Hybrid

Often reactive or proactive feature of a particular routing protocol might not be

enough. instead a mixture might yield a better solution. Therefore several hybrid

routing protocols are designed. Hybrid routing protocols have characteristics of

both table driven and on-demand routing protocols. Important hybrid routing

protocols are CEDAR, ZRP etc.

3.5.4 classification based on method of packet delivery

Based on the method of delivery of data packets from the source to destination,

classification of the MANET routing protocols could be done as shown in figure

3.2.

• Unicast Routing Protocols: The routing protocols that consider sending

information packets to a single destination from a single source.

• Multicast Routing Protocols: Multicast is the delivery of information to a

26


group of destinations simultaneously, using the most efficient strategy to

deliver the messages over each link of the network only once, creating copies

only when the links to the destinations split. Multicast routing protocols for

MANET use both multicast and unicast for data transmission.

– Tree-based multicast protocol: Mesh-based routing protocols use sev-

eral routes to reach a destination while the tree-based protocols main-

tain only one path.

– Mesh-based multicast protocol: Tree-based protocols ensure the less

end-to-end delay in comparison with the mesh-based protocols.

3.6 Important MANTEs Routing Protocols

• Dynamic Destination Sequenced Distance Vector Routing (DSDV):

DSDV is developed by Perkins and Bhagwat in 1994 [14]. It is a proactive

type of routing protocol in which a node in a network maintains a routing

table consisting all possible end to end routes in a network. It is an enhanced

version of the distributed Bellman-Ford algorithm where each node main-

tains a table consisting shortest distance and the first node in a route to every

other node in the network. It ensures loop-free paths to each destination by

efficiently handling count to infinity problem occurs in conventional distance

vector protocols. Each node creates, maintains and updates its own routing

table consisting destinations, next hop, hop count and sequence number. The

update mechanism is of two kinds, in first routing table entries are updated

by a full dump and in the second update is using an incremental update. In

full dump, the node sends complete table entries to neighboring nodes and

in incremental updates, only those entries are updated which have changed

since the last full dump. Problem with DSDV is that, whenever there are

topology changes, routing updates are broadcasted throughout the network.

For high-density network, this results in large control overhead and unneces-

sary time delays. Due to this DSDV is more suited for low-density networks

only. The main advantages of DSDV are that is ensures loop-free paths and

27


reduces the count to infinity problem. Another problem with DSDV is that

there is unnecessary bandwidth utilization due to the periodic broadcast of

routing information. [15].

• Dynamic Source Routing (DSR):

Dynamic Source Routing (DSR) [16] is on-demand source routing protocol.

In DSR node executes the process of path finding when it has data for a

particular destination. It is a source routing protocol wherein transmitting

source node construct the whole path and packet header consist the path to

be followed to reach the destination. DSR is designed to save bandwidth by

limiting the generation of control packets while updating the routing tables

in table-driven protocols. It is beaconless and does not requires periodic

hello packets to inform neighbors whereabouts of a particular node. In DSR

node keeps route cache information in the form of complete end to end route

for a pair of nodes in a network. Route cache information is updated during

data exchange and route discovery phase. Whenever a node (source node)

has data packet for particular destination node it (source node) checks route

cache table for a source to destination route. If route found than source node

constructs a source route in the packet’s header which includes addresses of

all intermediate nodes through which the packet should be forwarded in

order to reach the destination. Intermediate nodes check destination ad-

dress in a packet and forward it to next node (having an address in the

packet header) if it itself is not destination node. Upon receiving the packet

destination node reply through the transverse path to the source node. It

uses global flooding to find routes when there is no path to the destination

is available in route cache of the transmitting node. Source node broad-

cast a route request packets to all neighbors. The RouteRequest packet

refers destination as the target of the route discovery and keeps a record of

the address of all intermediate nodes. If route discovery is successful then

target sends RouteReply packet through the reverse path by route request

packet travel. RouteReply carries the path followed RouteRequest packet

to reach yhe destination node. In order to detect duplicate packets route

request packet carries sequence number generated by the source node and

28


time to live counter. Whenever there is route break, the adjacent node sends

RouteError message to source node. Source node re-initiates the route dis-

covery process when it receives RouteError message. Corresponding route

cache entry (of broken route) is removed by the source node and all inter-

mediate nodes who receives RouteError message.

Figure 3.3: (a) Route discovery process (b) Route reply process

In figure 3.3, the path setup process is shown for DSR. Let S1 is source

node and S8 is the destination node. Whenever S1 has a packet for S8

it looks into route cache for a possible route. If rout is available then the

packet is transmitted through that route. In the case when there is no

route in route cache S1 initiates route discovery process as shown in figure

3.3(a). S1 floods RouteRequest packet into network. The destination node

29


receives RouteRequest transversed from two paths, S1− S6− S5− S7 and

S1 − S2 − S3 − S4 − S9. Destination node S8 chooses one path based on

the route records in the incoming request packet and accordingly sends a

reply using the reverse path to the source node. As shown in figure 3.3(b)

the RouteReply packet follows reverse path S1 − S6 − S5 − S7 − S8 to

the destination. Upon reception of RouteReply, intermediate nodes update

their route caches. S1 then, forwards data packet through path mentioned

in RouteReply packet.

The main advantage of DSR is that it uses the reactive approach in which

eliminates the need to maintain routing table and transmission of periodic

beacons. It extracts latest route information available in data packets during

data exchange to update route cache. DSR does not repair broken routes

locally. Route caches are inefficient for a network with highly dynamic nodes.

• Ad Hoc On demand Distance Vector Routing (AODV): AODV is on-

demand reactive routing protocol [17]. It uses destination sequence number

to identify the most recent paths. All nodes in a network store the next hop

information corresponding to each flow for data packet transmission. When a

route is not available, source node floodsRouteRequest in the network to find

the desired destination. There are multiple replies to a single RouteRequest.

AODV selects a fresh route based on DestSeqNum. Node update next hope

information if the value of DestSeqNum is greater than the value stored at

the node. RouteRequest consist source identifier, a destination identifier,

source sequence number, destination sequence number, broadcast identifier

and time to live field. Destination node and the intermediate node can

send RouteReply if they have valid routes. Whenever the intermediate node

receives RouteRequest it checks its routing table for valid route to the desti-

nation. If a valid route available, it RouteReply to source node else forward

to next node. If intermediate node receives duplicate RouteRequest it dis-

cards using broadcast identifier in RouteRequest. Whenever intermediate

node forward RouteRequest or receive it stores broadcast identifier and ad-

dress of the previous node to form active paths. When intermediate nodes

update their routing table with latest DestSeqNum.

30


Figure 3.4: (a) Route discovery process (b) Route reply process

Figure 3.4 shows an example of AODV path setup mechanism. As shown

in the figure, let S1 is source node and S7 is the destination node. When

S1 has data packet for S8, it initiates route discovery process by flood-

ing RouteRequest packet into the network. Destination node (S8) receives

multiple RouteRequest through different paths as shown in figure 3.4(a).

Destination node selects an appropriate route based on prescribed criteria

and sends RouteReply through the reverse path as shown in figure 3.4(b).

Periodical beacons are transmitted to notify link breaks to source and des-

tination through link level acknowledgments. This is because AODV does

not repair route locally. When source node knows about link break it aborts

31


the transmission. When intermediate node detects path to break it send

RouteError to the source node.

The main advantage of AODV is that it is on demand routing protocol and

uses the latest end to end routes based on destination sequence number. It

has less connection setup delay compared to other on-demand routing pro-

tocols. The main disadvantage of AODV is that intermediate nodes can lead

to inconsistent routs if the source sequence number is old. It broadcasted

RouteRequest message to the target node in the form of flooding which in-

creases control overhead and adds in route establishment. In case of route

break, intermediate routes wait for fresh RouteRequest from source before

broadcasting RouteError, which causes a time delay. Fresh RouteRequest

may be discarded by downstream nodes to loopback, which affects the rout-

ing recovery. Due to the mobility of nodes, the time delay in route mainte-

nance reduce the utilization of network resources and therefore affects the

network performance. Periodic beacons leads to unnecessary bandwidth

consumption.

• Temporally Ordered Routing Algorithm (TORA): Temporally Or-

dered Routing Algorithm (TORA) is a reactive routing protocol with some

proactive enhancements. In this algorithm, the link between nodes is es-

tablished by creating a Directed Acyclic Graph (DAG) of the route from

the source node to the destination node. For route discovery process this

protocol uses a model called link reversal. A route request is broadcasted

and propagated throughout the network until it reaches the destination. An

intermediate node that has information about a destination can send in-

formation regarding how to reach the destination. TORA defines a unique

parameter called termed height. Height is a measure of the distance between

source and destination. During route discovery phase Height is returned to

the querying node. As the route query response from destination propagates

back towards the source, each intermediate node updates its table consisting

of height to the destination node. The source node then uses the height

to select the best route toward the destination. The main advantage of

TORA is that it frequently chooses the most convenient route, rather than

32


the shortest route. TORA tries to minimize the routing management traffic

overhead for all attempts made.

• Wireless Routing Protocol (WRP): Wireless Routing Protocol (WRP)

[18] is table driven proactive routing protocol. It uses an enhanced version

of the distance-vector routing protocol, based on famous Bellman–Ford algo-

rithm to calculate paths. WRP introduces mechanisms which reduce route

loops and ensures reliable exchange of data packets. It reduces the number

of cases in which a temporary routing loop can occur. Each node maintains

four parameters, distance table, routing table, link-cost table, and message

retransmission list (MRL) in order to make efficient routing. Routing table

entries contain distance to a destination node, the previous and next nodes

along the route. The link cost table maintains the cost of the link to its

nearest neighbors and the time stamp indicating the last event of success-

ful message exchange from the neighbor. The message retransmission list

(MRL) contains information about neighbors who has not acknowledged its

update message to the node and makes node to retransmit the update mes-

sage to that neighbor. In WRP routing tables are updated in two ways, first

by periodic exchange of routing tables with the neighbors via hello messages

and second during link state table changes. Upon reception of hello message,

neighbor node updates its distance table and computes the best route paths.

Hello messages also carry information regarding consistency check with its

neighbors which requires to eliminate loops and speed up convergence.

Advantages of WRP includes faster convergence and requirement of fewer ta-

ble updates. The main disadvantage of WRP is that the complexity of main-

tenance of multiple tables demands a larger memory and greater processing

power. During high mobility conditions, the control overhead involved in up-

dating table entries makes WRP not suitable for highly dynamic and large

networks.

• Zone Routing Protocol: Zone Routing Protocol (ZRP) [19] is most suit-

able for MANETs with large coverage area and highly node mobility. In

WRP network area is divided into different routing zones and each node

33


proactively maintains routes within the routing zone. The route to various

destinations is created using a query reply mechanism. Nodes first commu-

nicate with neighbors to create different routing zones in the network. To

reduce route query traffic, ZRP uses a query control mechanism by direct-

ing query messages outward from the query source and away from covered

routing zones. A node is called covered node to particular routing zone if

that has received a route query. During the process of exchanging query

packet, a node identifies whether query packet is coming from its neighbor

or not. If query packet is coming from a neighbor, then node marks all of its

known neighboring nodes in its same zone as covered. The query packet is

relayed until it reaches the destination. Upon reception of query packet, the

destination sends reply message via the reverse path and creates the route.

• Core-Extraction Distributed Ad-Hoc Routing Algorithm (CEDAR):

CEDAR [20] on-demand hybrid routing protocol where route computation is

performed by core nodes using only local state. CEDAR is robust and reacts

quickly and effectively to network dynamics while maintaining the routing

performance. It has three key components,

– Core extraction: The establishment and maintenance of a self-organizing

routing infrastructure called the core for performing route computa-

tions. Each core node maintains the local topology of the nodes in its

domain and also performs route computation on behalf of these nodes.

– Link state propagation: The propagation of the link state of high band-

width and stable links in the core through increase/decrease waves.

Slow-moving increase waves and fast-moving decrease waves, which de-

note corresponding changes in available bandwidths on links, are used

to propagate nonlocal information over core nodes.

– Route computation: A QoS-route computation algorithm that is exe-

cuted at the core nodes using only locally available state. The core path

provides the directionality of the route from the source to the destina-

tion. Using this directional information, CEDAR iteratively tries to find

a partial route from the source to the domain of the furthest possible

34


node in the core path. The computed route is a shortest-widest-furthest

path using the core path as the guideline.

3.7 Issues with existing routing protocols

• Routing techniques for existing networks have not been designed specifically

to provide the kind of dynamic, self-starting behavior needed for Wireless

Ad Hoc Networks.

• places too heavy computational burden on each mobile computer/node.

• The convergence characteristics of existing routing protocols did not seem

good enough to fit the needs of Ad hoc networks.

• No any realistic optimized solution for routing is available. Realistic perfor-

mance not/little available.

• No special provision for limited power available with node in wireless Ad

Hoc networks.

• Challenges like growing complexity, unreachable maintenance and unsecure

communication needs new mechanisms.

• Large control overhead.

• Absence of power saving mechanism.

• No mobility consideration.

• No mechanism to change route once communication established.

• Selected route may not be shortest and strongest.

3.8 Possible aids to improve routing

To improve routing process in MANETs, a large number of protocols and opti-

mizations are already proposed and many are under research. Possible aids and

35


techniques discussed in the literature to improve routing includes,

• Mobility modeling: Mobility models represent nodes distribution and

movement over the network. examples of famous mobility include, Ran-

dom Waypoint, Group Mobility, Freeway and Manhattan models. Pattern

of movements followed by the nodes in wireless Ad Hoc network play impor-

tant role in the performance of routing protocols. [21]. In this work, famous

routing protocols like AODV, DSR, DSDV, and TORA are compared based

on performance with different mobility models and concludes that selection

of appropriate mobility models has a major effect on the routing process and

routing efficiency. Studies in [22] [23] [24] suggest that routing performance

varies for different mobility models.

• Optimized flooding: Flooding is a popular broadcast scheme used dur-

ing the discovery phase of most Mobile Ad Hoc Network (MANET) routing

protocols [25]. Global flooding is one of the two commonly used meth-

ods in searching for a destination node in multi-hop wireless networks like

MANETs [26]. Studies in [27] [28] [3] [29] suggested that flooding during

route discovery process can be controlled to improve routing efficiencies.

• Bio Inspired Modeling: Bio-inspired solutions provides fuzzy intelligent

kind approach leads to Self organized, reconfigurable and optimized routing

process. In [30] [31] different bio-inspired models like ARS(Autonomous Net-

work Reconfiguration System), GP(Genetic Programming), EP(Evolutionary

Programming), PSO(Practical Swarm Optimization) and ACO(Ant Colony

Optimization) are discussed. This study suggests that bio-inspired models

increases routing efficiency in MANETs.

• GPS based solutions: GPS based schemes may be most suitable in certain

applications and situations like disaster and in remote military exercises.

In [32] location aided routing is proposed. Location-Aided Routing (LAR)

uses the node position and time stamp to consider the expected zone. This

information can be obtained by using the Global Positioning System (GPS).

In [33] author proposed routing protocol called PLAR for mobility models in

36


which target motion is known. In this work, LAR (Location Aided Routing)

is modified to use GPS information to predict the probable location of the

destination node. It uses the concept of request zone to find destination

node if it’s GPS location known to the source. Studies in [34] [35] [36]

discuss various routing methods based on GPS and location of nodes.

• Route Maintenance: Many solutions have been proposed for wireless net-

works to recover from link failures but still have several limitations. There

are resource allocation algorithms for initial network resource planning which

require global configuration changes, which are undesirable in case of fre-

quent local link failures. Above problem partially managed by greedy chan-

nel assignment algorithm. There are fault tolerant protocols such as local

re-routing and multipath routing but need multipath or retransmission or

redundancy which is not possible in wireless Ad Hoc networks [31]. There

is the possibility of introducing following concepts into existing routing pro-

tocols,

– Use of movement information [37].

– Broadcasting of handoff packets if node realizes it is moving in a thresh-

old zone to keep the link of data transmission unbroken [37].

– Make before break route repair mechanism [38].

– Backup the list of all active routes [39].

37

CHAPTER 4

Dynamic Power control

4.1 Introduction

Mobile nodes in MANETs are battery operated. Lifetime of node and ultimately

network depends on the life of a battery. Due to this energy conservation is very

important in MANETs. Various approaches are proposed to address this issue

including power control. In power control approach the transmission power is

varied based on predefined criteria such as transmission range. Power control

primarily dependents on three factors, transmit power, receive power and trans-

mission range. In MANETs, a packet transmitted from the source node is relayed

by intermediate nodes up to destination node. The distance between the relaying

nodes varied and therefore the value of transmission power cannot be the same.

For this type of situation value of transmission power cannot be same and should

be based on transmission range. Average transmission range significantly affects

the network topology and energy consumption. If the transmission range is large,

then the number of relaying hops are less and the number of transmission reduced

but this increases energy consumption per transmission. However, if the trans-

mission range is short, more relaying nodes are involved, increase the number of

transmissions but the energy consumption per transmission is fewer [40]. Proto-

cols of Media Access Control (MAC) sublayer of the network reference model plays

a key role in energy conservation. This chapter describes various energy consump-

tion strategies, power control protocols proposed, benefits of power control and

effects of dynamic power control on network performance.

38

CHAPTER 4. DYNAMIC POWER CONTROL

4.2 Energy Conservation Approaches

Mobile nodes in MANETs are battery operated and has a limited energy supply.

To increase lifetime of node, energy conservation is one of the key elements routing

protocols used for wireless ad hoc networks. Routing protocols for MANET can

be categorized into two broad categories based on energy conservation approach

wise minimizing energy during the active and inactive period. During active pe-

riod when nodes transmit and receives packets it consumes energy whereas in the

inactive period it is required to switch node into sleep mode using wherein energy

consumption should be minimum [41] [42]. There are two different approaches

of energy conservation in the active period, using the dynamic value of transmis-

sion power and load balancing or load distribution according to available battery

power [43]. Sleep or shut down approaches uses different scheduling strategy to

switch to and from different modes of operation [44]. Based on energy conservation

approach, various routing protocols are categorized as shown in figure 4.1.

Network lifetime is the important issue in ad networks and refers to a period

wherein the first node in a network runs out of battery during communication

process. Different strategies can be opted to increase network lifetime as mentioned

below,

• Power Monitoring: Constant monitoring of power so that node in active

communication will not run out of battery.

• Load distribution: If a node left with critical power due to constant load

then the task should assign to the adjacent node.

• Route selection: Selected route should consume minimum power like a se-

lection of shortest route or route with minimum load.

With reference to network reference model in figure 4.2, energy conservation mech-

anism can be implemented at Physical and data link (MAC) layer [45] [46]. MAC

layer protocols uses two approaches to achieve energy efficiency [47],

39


MANETs Rout-ing Protocols

based on energysaving approach

Managing en-ergy during

inactive period

Sleep mode

SPANGAFPEN

Managing en-ergy during

active period

Transmissionpower control

COMPOWFARPLRMERRAR

Load balance

LEARCMMBCR

• FAR: Flow Augmentation Routing

• LEAR: Localized Energy Aware Routing

• MER: Minimum Energy Routing (MER)

• CMMBCR: Conditional Maxmin Battery Capacity Routing

• PAR: Retransmission Energy Aware Routing (RAR)

• GAF: Geographic Adaptive Fidelity

• COMPOW: Smallest Common Power Routing

• PEN: Prototype Embedded Network

Figure 4.1: Classification based on the method of energy saving approach

40


• Power control: Value of transmission power of a device is controlled.

• Power management: Nodes switch to different working modes (transmit,

receive, idle and sleep) in order to conserve energy.

Figure 4.2: Layers in network reference model

Other important ways to conserve energy is to limit retransmissions and by iden-

tifying appropriate power level for retransmission by the involving nodes at data

link layer. At network layer approach of routing protocol also can save the en-

ergy. Distributed routing approach in which the packet relaying load distributed

evenly among the participating nodes can save energy and increases the network

lifetime. The end to end path should be shortest in order to reduce the number

of transmission attempts. The transport layer affects the quality of service in the

network. The main aims of this layer are to establish and maintain end to end

connections, ensure reliable end-to-end delivery of data packets, flow control, and

congestion control.

41


4.3 Power control

In mobile networks, power control is successfully implemented and used to save en-

ergy of mobile nodes. Power control in ad hoc networks is more critical compared

to mobile networks because nodes in an ad hoc network need extra energy to com-

municate and send data to neighboring nodes during hop to hop communication.

By opting the lowest power level that can maintain connectivity of ad hoc network

performance level of the system can be improved. Power control enables ad hoc

networks to improve many key aspects like including routing, power consump-

tion, clustering, interference distribution, throughput, connectivity and backbone

management. Power control and choice of power level is very important as it has

the indirect impact on networks physical layer, data link layer, network layer and

transport layer by determining the quality of the received signal, transmission

range and level of interference [48] [49] [50] [51]. Transmission power control has

following benefits towards system performance [52],

• The connectivity: Choice of transmission power level ensures the connectiv-

ity of the network. Successful communication between nodes relies on re-

ceiving and decoding received frames correctly. Transmission power control

can affect this process as the transmission power has an impact on whether

a frame will overcome interference, attenuation and signal distortions during

transmission. In order to provide a stable level of connectivity, if connectiv-

ity and link reliability drop below the critical level, the transmission power

level can be increased. Apart from this asymmetric links can be minimized

in order to maintain connectivity using minimum power level.

• Intermediate Nodes: Number of relaying nodes within transmission range

has a direct impact on the throughput of the links, due to contention among

the nodes. By altering the transmission power, the number of competing

nodes will be reduced and so fewer retransmissions will be needed in order

to send data.

• In terms of energy: The higher the transmission power, the higher the energy

42


consumption and vice versa. However, if the transmission power is too low

then there may be problems with the link’s reliability, data rate, and quality.

The transmission power control mechanism must ensure a balance between

energy consumption and efficiency.

4.3.1 Effects of low and high transmission power control

Low transmission power increases battery life and hence extends network lifetime.

For the dense network, low transmission power distributes and reduce interfer-

ence which reduces packet loss and thereby increases the system capacity. But

for sparse networks, low transmission power may create a connectivity problem.

For such networks, the number of relaying nodes increases and the end to end la-

tency is reduced due to increased network load. Whereas high transmission power

consumes high energy and reduces battery lifetime. It creates high interference

resulting in lower system capacity due to high packet loss. For dense network, it

increases the number of neighbors and therefore large routing tables to be main-

tained and control overhead also increases. For sparse networks few intermediate

relaying nodes involved between source and destination. The end-to-end latency

is lower with low network loads, higher loads result in delays due to interference.

4.3.2 Effects of fixed and variable transmission power

Fixed transmission power ensures that nodes within the same range can hear each

other with the same effect. In the case of variable transmission power, when two

nodes are not in the same range, one node can hear the other, but the reverse may

not true [53]. It is shown that variable transmission power scheme is better com-

pared to fixed transmission power because in prior nodes uses the minimum energy

required to send the packet whereas in later the transmission power may waste

energy by using more than actually required to transmit the data. Fixed power

ensures that links are bidirectional, which is assumed in most distributed rout-

ing algorithms. However, there are fewer routing algorithms suitable for variable

43


power as the links are not bidirectional.

4.4 Examples of power control protocols

Various power control protocols are proposed for mobile ad hoc networks. Authors

in [54] proposed power control protocol called is COMPOW which is based on the

selection of common power level for all nodes in a network. COMPOW provides

bidirectional communication between nodes. There are six different power levels

corresponding to values of signal to noise interference ratio (SINR). To minimize

the interference value of transmission power should be low and is to be equivalent

to minimum SINR values of participating nodes in a link. While implementing

power control COMPOW ensures better connectivity, minimum interference, pro-

vides power aware end to end links, limits MAC contention and is compatible with

almost all proactive routing protocols.

CLUSTERPOW [51] provides both clustering and power control. Without con-

sidering the position of a node, it clusterise network according to transmit power

level. It is best suited for non-homogeneous networks. CLUSTERPOW enhance

network capacity by providing loop-free efficient routing. Tunneled CLUSTER-

POW [55] is modified version of CLUSTERPOW. It provides both power control

and clustering but more complex to implement. Instead of direct packet transmis-

sion it uses hope to hop data delivery using lower power levels. MINPOW [55] is

another routing protocol which is based on the concept of clustering. MINPOW

uses the optimal value of power to awake nodes to increase energy efficiency. Work-

ing of MINPOW is based on the concept of link cost and is implemented at the

network layer of the network reference model.

PARO [56] is another power-aware routing protocol. It uses redirectors between

distant nodes to minimize transmission power required to forward the packet.

As a number of redirectors increases the value of transmission power becomes

lower. PARO is better suitable for static and dynamic environments. Working of

PARO is primarily based on overhearing, redirecting and route maintenance. It

44


is shown that its power conserving approach in point-to-point design, it is more

efficient than traditional, broadcast-based routing protocols. It reduces the overall

transmission power required and increases the operational lifetime of mobile nodes

and the network.

4.5 Power management

Power management is another way to conserve battery power of node in ad-hoc

network. Since nodes are not always in working mode, it is desirable to stop

unnecessary processes during this time. power management is a technique by

which nodes stops the certain process as required. Status of a node changes the

modes of operation while power management is applied. Nodes can stop all the

process and enters into power saving mode when there are no packets to transmit

or receive. Nodes wake up and turn back to operational mode whenever there

is data to transmit or receive. Different operating modes which can be used by

nodes in ad-hoc networks are mentioned below [57].

• Transmit mode: In this mode, the sender is in the active position and sends

packets to neighboring nodes. This is the mode in which node consumes

the highest energy compared to other modes of operation. In this mode,

major power is consumed in processing and transmission of a packet from

the antenna through a wireless link. During this mode, almost all layers of

the reference model are active to complete the transmission process.

• Receive mode: Receiving mode operation consumes slightly less energy com-

pared to transmit mode. In this mode, receiver receives data from the sender

and consumes energy to process that packet in order to forward it to the ap-

propriate neighbor node.

• Idle mode: This is the mode in which node is only able to listen and notice

the activities going around. Node is able to listen to wireless link or the

medium constantly. Node is always in a state to receive or transmit data

45


to/from neighbor nodes in a network. There constant consumption of power

even there is no any effective activity going on.

• Sleep mode: In sleep mode, the activity of node is minimum and it consumes

minimum energy compared to all other modes of operation. In this node

stops to listen to wireless link and not able to transmit or receive packets.

4.5.1 Importance of power management in ad hoc net-

works

Since nodes in ad-hoc networks are powered by batteries with limited supply

capacity, it is required to limit the uses of power during various activities. Another

factor is hop to hop communication where battery life of relaying node is ad

important as sender or receiver node to increase network capacity. The aim of

power management in ad hoc network is to maximize and regulate the use of node

battery. Important aspects behind power management are discussed below [58].

• Battery capacity: Quality and capacity of the mobile battery is very impor-

tant to increase network lifetime. Considering mobile activities the available

batteries always lags to provide long life. Therefore mobile activities can be

minimized according to the situation to save energy.

• Battery recharge and replacement: In emergency situations, it is not possible

to replace or recharge the battery while communication going on. Due to this

power management is crucial for the efficient working of ad hoc networks.

• Optimal transmission power: Selection of the minimum value of transmission

power is important for network connectivity. If the value is higher increases

energy consumption and interference. The transmission power affects the

reachability among the nodes in a network and thus the ideal transmis-

sion power should decrease interference between nodes while consequently

increasing the number of simultaneous transmissions.

46


4.5.2 Examples of power management protocols

Different methods of power management are suggested for ad hoc networks. Here

some of the important techniques proposed are discussed in brief. Authors in

[59] [60] proposed power managing scheme in which nodes uses concept of power

balancing to reduce power consumption. The concept of clustering is used to con-

clude that varying power and dynamic Power management with power variance

to assess the effects of power balance extends the network lifetime and reduces

average power consumption. Power awareness during route selection is important

because a node with reduced available power in the functional link may create

problems during the conversation. Monitoring the power status of the node (Low,

high, medium) and selecting nodes with high or medium battery reduces the risk

of frequent link failures [61]. The author in [62] mentions the notion of reducing

delay while route selection and suggest the use of higher transmission power to

reduce the transmission delay time and frequent route breaks. Power management

approach in [63] uses timers for nodes to record, adaptive techniques to distribute

traffic and managing power transitions on the intelligent way. In this timers are

set to monitor transmissions of control and data packets so that switching modes is

smooth and less power consuming. Kind of routing approach has a major impact

on energy consumption. Author in [64] modifies Location-Aided Routing (LAR)

protocol, uses GPS to find probable location of the destination node in the ex-

pected zone and minimizes transmission of the extra control packet to control the

power consumption in the transmission of unnecessary control packets. It uses the

concept of dynamic power transmission based on the distance between nodes to

improve overall power efficiency of the system. The routing process at MAC can

increase power efficiency by reducing the number of retransmissions, exchanging

minimum control packets and reducing the number of broadcasts during route

discoveries [65] [66]. Author in [67] presents energy aware AODV (EA-AODV)

that uses beam forming to improve the physical layer and introduces energy aware

routing to conserve energy. Work proposed in [65] tries to reduce the number of

collisions at MAC level so that retransmissions are reduced. Literature in discussed

work concludes that choosing optimal SIR threshold increases the performance ef-

47


ficiency of the network, concentrating network and MAC layers minimize energy

consumption and power-aware routing at MAC layer improves packet delivery ra-

tio and reduces control overhead. Works in [68] aims to reduce the number of

intermediate hops by using maximum transmission power. By reducing the num-

ber of hops reduces node processing power and transmission of control packets.

Based on the received signal strength at each node, only those nodes are allowed to

participate in link formation who has maximum possible distance. Study in [69]

focuses on Energy Efficiency (EE) optimization based on the cross-layer design

paradigm. Combining power control, routing process, and traffic scheduling, the

nonconvex mixed integer nonlinear programming (MINLP) formulated. It also

includes upper and lower bounding schemes and branching rule based on a non-

convex MINLP algorithm. In work carried out in [70] focuses to control excessive

use of battery by a node using various schemes. Link stability control Maximum

(MAX) energy with multipath routing scheme is proposed to increase the energy

efficiency and the network connectivity. The proposed algorithm always selects

the neighbor nodes to have the highest energy among all neighbor nodes. To

save energy of intermediate nodes it selects them according to MAX energy level

while forming end to end path between source and destination. The sender se-

lects those nodes with a high value of MX while forming the route to balance and

distributes energy consumption among the nodes. In [71] author showed that a

minimum power network design that addresses the increase in transmit power to

handle large-scale variations is fundamentally the same as a design that considers

only the path loss. Therefore, to find minimum transmission power over a given

distance we considered only path loss component.

Authors in [72] focuses on the problem of non uniform load distribution in ad hoc

networks. It combines GPS based dynamic channel allocation algorithm and co-

operative load balancing algorithm to select a channel based on available resources.

In [73] efficient power-aware routing (EPAR) is proposed that can improve net-

work lifetime in high mobility environments. It calculates both residual energy

and expected energy consumption of a node to identify nodes capacity. Another

important characteristic of EPAR is that it uses min-max formulation to select a

path that has maximum packet capacity at minimum packet transmission capac-

48


ity. Problem with EPAR is that it generates extra control packets to calculates

expected energy spent in forwarding data packets which increases control over-

head. Overall literature survey on power control suggests that the combination of

various power control techniques can increase the network throughput, maximizing

the network lifetime, better packet delivery, limiting end-to-end delay, reducing

overheads and overall better ad hoc network performance.

49

CHAPTER 5

GPS aided routing

5.1 Introduction

As discussed in previous chapter routing is the process of delivering data packet

from source node to destination node. Due to the mobility of nodes and absence

of fixed network topology, the routing process is very complex in MANETs. If

precise locations of both transmitter node and receiver nodes are available, then

the process of routing could be very easy and effective [74] [75]. In position-based

routing approach the exact geographic location of nodes are obtained and routing

is done on the basis of parameters like distance(calculated using geographic coor-

dinates). With the help of technique like Global Positioning System (GPS), the

precise locations of nodes can be obtained. Position information of nodes can be

used to find the shortest and efficient route between transmitting and receiving

nodes. Using position information, the distance between two nodes and then the

required transmission power between respective nodes can be calculated. GPS

information can also be used to find relative positions and movements of neighbor

nodes. Use of GPS in routing is justified due to easy, low-cost availability and

low power consumption of GPS receivers. The position-based approach in routing

becomes practical due to the rapidly developing software and hardware solutions

for determining absolute or relative positions of nodes in indoor or outdoor ad

hoc networks. Another issue is scalability of the network. It has been experi-

mentally confirmed that routing protocols (like AODV, DSDV, DSR) that do not

use geographic location in the routing decisions are not scalable [76] [77] [78]. In

this chapter position based routing, research in the area of position based rout-

50

CHAPTER 5. GPS AIDED ROUTING

ing including its issues and challenges are discussed. Proposed GPS aided energy

efficient routing techniques are discussed in later sections of the chapter.

5.2 Position based routing

Routing protocols can be categorically described based on three aspects: sim-

ulation scenario, characteristics and protocol prerequisites. As discussed in the

previous section, the majority of position-based routing protocols employ greedy

forwarding algorithm. On-demand reactive routing algorithms are best suited for

scenarios where node mobility is high and nodes are frequently joining and leav-

ing the network. Similarly, different routing protocols are more suitable for other

scenarios, kind of next hop selecting algorithms and forwarding strategies. There-

fore particular routing protocol may perform well for some scenario and gives an

average performance for the different scenario. Selection of routing protocol for a

particular scenario should improve throughput, packet delivery ratio(PDR), end

to end delay and control overhead [74].

Position based routing protocol utilizes position information to locate the source,

destination, and intermediate nodes. It is shown that position information plays

important role in order to make efficient routing. The exact geographic location

can be obtained from location services like Global Positioning System (GPS).

Position based routing has been proved to be better compared to topology-based

routing. The main advantage of position based routing is that it exhibits better

scalability, robustness against frequent topological changes. Problem with position

based routing is that it encounters the local maximum problem where forwarding

node fails to find appropriate next relay hop towards destination due to lack of

availability of position information. In some scenarios, geographical information

derived from a digital map can assist the transmitting node to select the next

relaying node.

51


5.2.1 Literature Survey

There have been many position based GPS aided routing protocols proposed for

different applications like sensor and Vehicular ad hoc networks (VANETs). In this

section important position based routing protocols that have been proposed, rout-

ing aspects, open issues and challenges are discussed. Greedy Perimeter Stateless

Routing (GPSR) [79] is a classical position-based (geographic) routing algorithm

designed specifically for vehicular ad-hoc networks(VANETs). To make efficient

routing and forwarding decisions, GPSR uses geographical positions of the source,

destination, and intermediate nodes. GPSR finds the exact geographical location

of its neighbor and next hop by identifying the vehicle which is geographically

closest to the destination. The mobility of vehicles makes planarization of the

graph difficult. For highly dynamic network scenario, recovery strategy of GPSR

is inefficient and time-consuming. The performance of GPSR is better for open en-

vironments where nodes are evenly distributed and performance suffers in presence

of obstacles.

Greedy Perimeter Coordinator Routing (GPCR) [80] aims to improve the perfor-

mance of Greedy Perimeter Stateless Routing (GPSR). GPCR is based on the fact

that streets and junctions form a natural planar graph and does not use global

or external information such as a static street map. GPCR operation divided

into two parts, first, controlled greedy forwarding strategy and a second, repair

strategy. Repair strategy of GPCR does not require a graph planarization al-

gorithm because it is based on the topology of real-world streets and junctions.

GPCR improves routing performance by improving the node topology planariza-

tion mechanism and transmission of a signal in none line of sight (NLOS) areas.

However, the routing protocol still has following three defects:

1. Increased overhead due to the process involving identification of nodes pres-

ence on streets or junctions.

2. GPCR mostly depends on the node that presents at the junction for routing

coordination.

52


3. Coordinator node transmits many packets which increase overhead and col-

lisions.

In [80] Position-based Directional Vehicular Routing (PDVR) is proposed for Ve-

hicular ad hoc networks (VANETs). It is based on the assumption that all nodes

are equipped with GPS receivers and can acquire accurate geographic location

and velocity. In order to select next hop and deliver packets to destinations suc-

cessfully over efficient and stable routes, PDVR combines two packet forwarding

strategies. PDVR maintain stable and efficient routes by considering mobility in-

formation of the vehicle and by selecting the next-hop vehicle based on its position

information, the direction of movement and the position of the destination node.

PDVR performance better when the roads are straight.

Directional greedy routing (DGR) [81] is a position-based routing protocol for

Vehicular ad hoc networks (VANETs). To acquire exact position of the vehicle it

uses GPS and static map. DGR assumes that all vehicles are equipped with GPS

receivers and other sensors to acquire its exact location and mobility information

and if these location services are available, the location and position of destination

can be obtained easily. DGR forwarding strategy is based on the directional greedy

forwarding approach which uses the vehicular direction.

Predictive directional greedy routing (PDGR) [82] is an extended version of Di-

rectional greedy routing (DGR). PDGR is based on the same assumption as that

of DGR that if the exact geographic location is acquired then it is easy to locate

the destination vehicle. All vehicle broadcasts combined information consisting

position of itself and its one-hop neighbors. The forwarding strategy of PDGR

is based on the directional greedy forwarding approach. Problem with PDGR is

that while acquiring next hop neighbor information it generates large overhead

which consumes extra bandwidth. Both the protocols (DGR and PDGR) are

implemented and tested in straight road scenario where it performs well. Both

protocols need modifications to implement in the urban environment where the

roads are not straight enough.

Geographic Source Routing (GSR) [83] is specifically designed for routing in an

53


urban environment. GSR assumes that each vehicle is equipped with GPS and

a digital map of the concerned area. Onboard GPS and the digital map help

to generate the topology structure for routing purpose. The main advantage of

GSR is that it uses digital map, positions of the source and destination nodes to

calculate next node at the junction of the road. This overcomes the problems in

position based routing due to network unavailability, errors due to large vehicle

density and wrong vehicle movements.

Position based power-aware routing algorithm is described in [75]. It employs

smart routing based on mathematical structure and intuition. It calculates the

optimum value of transmission power for two communicating nodes assuming that

additional nodes can be placed in the future whose desirable position is described.

It is intuitional attempt to find the forwarding neighbor who is as close as pos-

sible to destination node but also near to forwarding node for the optimal power

transmission.

5.2.2 Open issues and challenges

The accuracy of the location service is very important in position based routing.

Accuracy and efficiency of position based routing protocol highly depend on accu-

rate position information obtained [84]. In position-based routing, exchange and

update of position information among node is another challenge. The choice of

updating position information can significantly increase the overhead. Therefore

designing location update schemes to provide accurate destination information

and enable efficient routing in mobile ad hoc networks is as difficult as routing

itself [84].

To provide efficient routing in a different type of ad hoc networks such as VANET

and MANETs, position based routing has certain challenges like sharing and ac-

quiring accurate position of the node. Routing of packets from source to desti-

nation consists two distinct phases, first finding the accurate position of source

and destination node and second successful transmission of a packet from source

to destination based on position information of destination. There are several

54


techniques to acquire the position of a node like using GPS and GNSS (Global

Navigation Satellite System). GPS receivers are very economical and available on

board of all vehicles and are integrated parts of almost all communicating devices

such as cell phones. Both GPS and GNSS provides accurate location provided that

multiple satellites are in view. Problem with these systems is that position accu-

racy may not the same for different geographical and environmental conditions.

Digital map based positioning is an important option for urban areas. Sharing of

latest location information among node participating node is important in order

to achieve efficient routing. Various methods suggested in literature includes,

• Flooding: Hello packets consisting position information are flooded through

the network. Participating nodes updates the knowledge of other nodes

positions on ad hoc basis. The frequency of hello packets depends on the

mobility of the nodes and lifetime of hello packet depends on the size of the

network in terms of area.

• Quorum-based: It is based on the identification of overlapping groups of

participants. Update queries and position information is transmitted to

selected groups only. The advantage of this strategy is that since the groups

are overlapped, updates and queries are easily shared among that groups.

• Grid Location Service (GLS): It divides network area into a hierarchy of

squares. Each node in a square maintains a table of all other nodes within

the adjacent square. The table is constructed and updated using periodic

beacons consisting position information.

• Homezone algorithm: In this position information for a node is stored. The

position C of the Homezone for a node can be derived by applying a well-

known hash function to the node identifier. Nodes within circular area of

radius R centered at C have to maintain position information for the node.

Based on acquired position information, the process of forwarding packet to the

destination is challenging due to nature of ad hoc networks. In all cases, multiple

routes to the destination are available, out of which best route should be selected

55


based on criteria like distance and traffic on that route. Routing process has two

phases path setup and packet forwarding. Both tasks can be done using different

techniques like in LAR where it uses position information for path setup and then

actual data packets are routed with position independent technique. This type of

approach is very effective for situations where less number of packets are to be

transmitted and reliability is important. Forwarding of packets based on available

position information can be done using any of strategy discussed below [85].

1. Greedy forwarding: It forwards packets in the direction of the approximate

location of the destination. Protocols that use greedy forwarding do not

establish and maintain paths from source to destination. In this strategy,

source node put the approximate position of destination in the data packet

and selects the next hop depending on the optimization criteria of the al-

gorithm. All intermediate hops follow the same process until data packet

reaches to the destination. Periodic beacons are transmitted in order to

update and exchange position information among the neighbor nodes. If

proper position information of intermediate nodes is not available greedy

forwarding strategy leads to dead end.

2. Controlled flooding: In controlled or restricted flooding, the sender broad-

casts the packet to neighbors towards the possible location of the destination

node. Intermediate node checks the packet content and decides whether the

packet is to be forwarded to next based on criteria such as lifetime of the

packet. An advantage of this strategy is that less number of nodes involved

which restricts the control overhead and there is a high possibility of find-

ing the most reliable path to the destination. Another important aspect of

controlled flooding is that it is robust against the failure of individual nodes

and position inaccuracy.

3. Hierarchical Routing: Hierarchical forwarding strategy forms hierarchy in

order to scale down a number of nodes. Sometimes combination of nodes

location and hierarchical network structures is used such as in zone-based

routing.

56


5.3 GPS Aided Routing - Proposed Technique

In previous sections, the importance of position based routing is discussed. From

these discussions it is clear that position based routing can offer better routing

solution for MANETs compared to other techniques. In following sections, we see

that if locations of transmitter and receivers are obtained, the routing process is

easy, fast and less complex compared to topology based routing techniques. In

this section, we discuss proposed position based GPS aided routing technique that

uses GPS information to locate a node in a network, find the distance between

nodes and calculate relative motion between a pair of nodes. The aim of work is

to optimize available routing protocols (AODV, DSR) using proposed GPS aided

routing. Proposed GPS aided routing technique can find the shortest end to end

route by consuming minimum power. Key features of proposed GPS aided routing

technique are,

• GPS locations of node: It acquires exact GPS locations of nodes and ex-

changes this location information among the participating nodes. When net-

work initializes all nodes exchange location information using hello packets.

Once the network initialization phase over, the exchange of GPS information

is done during data exchange and route discovery process.

• End to end routes: Finds the shortest end to end routes in terms of length

and thus reduces end to end delay time. During the route discovery process,

GPS location information is used to find the nearest node to the destination

in a route. At the end of route discovery process, the formed route consists

shortest route in terms of distance and number of nodes.

• Dynamic transmission power: Transmitting node transmits a packet

with an optimized value of transmission power based on distance to receiving

node. The distance between the transmitting and receiving node is calcu-

lated and based on this distance value of transmission power is calculated.

This process is done at node level where each node stores distance to all

its neighbors with minimum value of transmission power required to send a

57


packet to that node.

• Mobility considerations: Considers mobility of node while selecting it as

a relay node in a route. Using GPS location information, the relative speed

of the pair of nodes is calculated. This information is used during route

discovery to select the next node in a route. If relative speed between a pair

of nodes in a route is more than the prescribed value, the next node cannot

be selected as a relay node in a route.

• Controlled flooding: Uses controlled flooding during the route discovery

process. Using timers, initially route request packets transmitted in first-tier

nodes, and then the value of the timer is increased up to the second-tier of

nodes. During route discovery, if location information of destination node is

obtained, the route discovery process is aborted.

• Route maintenance: Mends broken routes locally without consuming ex-

tra control overhead. If a node in a route moves away, node before that

node in a route finds alternate relaying node using GPS information of des-

tination information. This is done by finding neighbor who is nearest to the

destination node.

Haversine formula is used to calculate the distance between the pair of nodes. It

is a well known mathematical equation which uses GPS information to find the

distance between two points on earth. A noble power model is also proposed to

calculates the minimum transmission power required based on calculated distance

to the receiver. The concept of relative speed is used to find the efficient rout

in terms of rout lifetime using GPS location information of nodes. In proposed

method GPS location of nodes in a network are obtained/updated based method

on proposed in [77], which has the following key features,

• Each node obtain its own GPS location in the form of longitude and latitude.

• A node announces its GPS location and unique ID to its neighbors (other

nodes within radio range) by broadcasting periodic HELLO packets.

58


• Each node maintains a table of its current neighbor’s unique ID and geo-

graphic positions.

• The header of a packet destined for a particular node contains the destination

and source unique IDs as well as its geographic position.

Figure 5.1: Path setup process

If GPS location of destination node is available, then source node initiates path

setup process. The source node transmits RouteRequest (RREQ) to its neighbor

node having GPS location most nearer to the destination node and satisfies mobil-

ity condition (Discussed in next section). If neighbor node is not the destination

node, then it transmits RREQ packet to next neighbor having GPS location most

nearer to the destination node. Destination nodes reply with RouteReply (RREP)

packet on transverse path upon receiving RREQ after that exchange of data may

take place. This procedure continues until destination node found or hope counts

expires. If this method fails or GPS location of destination is not available at

source node then it follows conventional method with mobility information to es-

tablish a route between the source and the destination node. An example scenario

in figure 5.1 shows how the path is set up between the source node and the des-

tination node. In this example values of X and Y − axis are assumed equivalent

59


to GPS longitudes and latitudes while height kept zero (ground level). N7 is as-

sumed to be source node and N1 is destination node. It is also assumed that N7

has GPS information of N1. Now N7 initiated route discovery to N1. The steps

are,

1. Source node N7(3, 7) compares destination node N1(8, 2) with neighbor

nodes N3(5, 8), N5(2, 5) and N4(5, 5).

2. N4 is winner node in step - 1 so N7 sends RREQ to N4.

3. N4, N2 and N10 repeat same procedure to forward RREQ.

4. Destination node N1 replies with RREP intended to destination node N7

on reverse path traversed by RREQ.

Figure 5.2: Route maintenance process

Whenever there is route break it is required to find an alternate route. In proposed

method route maintenance is done at the node level. If a node in a route finds

route breaks than it uses GPS location of next possible hop using its path cache

and routing table. The process of finding alternate hop is explained using example

in figure 5.2. Here N10 move away and therefore the link between N2 and N1

60


breaks down. As intermediate node N2 finds an alternate route to N10 through

N9 and N8. N2 follows the same process which is explained in the path setup

process. Most of the times whenever destination or intermediate node moves by

predetermined units of GPS location its neighbors lose contact due to limited

coverage range. This makes such neighbors (which are also intermediate nodes

in the active path) try to establish an alternate path to the destination. Due to

this route breaks detected easily at the local level and route maintenance process

becomes fast. If an intermediate node fails to find alternate route then it sends

RouteError (RERR) message to the source node. When the source node receives

RERR message then it initiate the route discovery process.

Haversine formula [86] [87] is used to calculate the distance between two nodes.

It is an important equation in navigation to calculate distance on earth. Ignoring

ellipsoidal effects, if GPS locations of two points (let i = 1, 2, 3.. (up to number of

neighbors) and j = destination node as shown in figure 5.3) on earth are available

then shortest distance (di,j) between these/respective two points on surface of

earth is calculated as,

di,j = R.c (5.1)

Where,

a = sin2(∆Φi,j

2 ).cosφi.cosφj.sin2(∆λi,j

2 )

c = 2.atan2(√a,√

1− a)

∆Φi,j = φi − φj∆λi,j = λi − λjΦi and λi = Latitude and Longitude of i

Φj and λj = Latitude and Longitude of j

R = Earth Radius(Mean Radius=6371km)

Figure 5.3: Distance calculation between nodes

During the route discovery process, relative speed and direction of the node to

61


be selected as next relaying node is taken into account to avoid frequent route

breaks. During route discovery process sending node differs from sending RREQ

to a node that is moving in the opposite direction or moving away during route

discovery phase as shown in figure 5.4. Here three possibilities of node directions

are shown. In first case, two nodes are moving in the same direction, in second

both nodes are moving in the opposite direction and in the third case both nodes

are moving away from each other. If we select the nodes in second and third

cases as relaying nodes in a route, there is a high possibility of rout break. To

avoid frequent route failures, It is required to consider relative motions of neighbor

nodes. Selection of node with comparatively less relative speed to form end to end

link minimizes rout breaks that occur due to the random mobility of nodes. Using

ns3 :: MobilityModelClassReference and available GPS location information of

nodes we have calculated relative speed between two nodes. To calculate relative

speed between two nodes following formula is used,

RSi,j = |Ni(t)−Nj(t)| (5.2)

Where, Ni(t) and Ni(t) are speed of node i and j respectively.

Figure 5.4: Relative movements of nodes

Since the nodes in MANETs are battery operated, energy and power conservation

is very important. Among various approaches suggested in literature is power

control by various means to increase the lifetime of the network. Power control

is primarily dependent on the transmission power, received power and transmis-

62


sion range. Overall energy consumption of network is significantly affected by the

average distance between nodes in a network. If a selected end to end routes are

shortest, the average energy consumption is minimum. There are two approaches

to achieve energy efficiency, first by power control, where the transmission output

power of a device is controlled to reduce interference and second power manage-

ment, where nodes switch into different modes like transmit, receive, idle, sleep in

order to conserve energy.

Various models have been proposed in literature to predict the value of transmit

and receive power [88] [89] [90]. The study suggests that the propagation charac-

teristics of the signal varies over frequency bands and requires different prediction

models. The simplest approach to calculate path loss and finally, the optimal

value of transmitted power is using Friss power transmission formula given by the

equation,

Prj = PtiGtGrλ2

(4πdi,j)2 (5.3)

Where, Prj is received power (at node j) which is function of distance (di,j) between

two node i and j, Prj is power transmitted (from node i), λ is the wavelength of

the signal, Gt, Gr are transmitter and receiver antenna gain respectively.

Path loss (Pli,j) is ratio of Pti and Prj, for free space model it is given by,

Pli,j = PtiPrj

= GtGrλ2

(4πdi,j)2MlNf

(5.4)

Refering system model proposed in [91], the outage probability of transmission (as

in Nakagami - m fading model [92]) is given by,

Oi,j '1

Γ(m+ 1)

(mNβ

Pti,jPli,j

)m(5.5)

Fixing Oi,j at packet loss limit O∗i,j, the optimal transmission power between two

63


nodes (i and j) is given as follows:

Pti,j = mNβ

Pli,j m

√Γ(m+ 1)O∗i,j

(5.6)

Where,

d = distance

Gt = Gr = Transmitter and receiver antenna gain

λ = Wavelength

Pt = Transmitted power

Pr = Received power

m = Nakagami-m dist. parameter (related to fading)

Ml = Link Margin

Nf = Noise figure

B = System bandwidth

N0 = Noise density

N = Noise power spectral density (= N0B)

β = 24 − 1 (Threshold below which outage occurs)

4 = System spectral density.

Considering the energy consumed by the transmitting and receive circuitry, total

Energy consumed per bit during transmission is given by,

Eb = Pti,j + PTX + PRXRb

(5.7)

Where,

PA = Power consumed by amplifier

PTX = Power consumed by transmitter circuitry

PRX = Power consumed by receiver circuitry

Rb = Bit rate.

64


5.4 GPS aided AODV

As discussed in the previous chapter, Ad-hoc On-demand Distance Vector Routing

(AODV) [17] is one of the most suitable routing protocol for MANETs. AODV

allows dynamically self-organized multihop routing between participating nodes

in MANETs. A node in a network can obtain quick routes to new destinations

and there is no need to maintain inactive routes. AODV provides efficient and

quick mending of broken routs during active communications. Working of AODV

mainly consists route discovery process and route maintenance process. Node

stores information of next node in a path to a particular destination and keeps

this information up to date using destination sequence number. Destination se-

quence number indicates the latest sequence number received in the past by the

originator for any route towards the destination. If the route to destination is

available in routing table then data packet is transmitted through that route.

Source node initiates route discovery process if route to destination is not avail-

able in routing table. During route discovery process source node broadcast hello

message into network. In a case when there is route break, route maintenance

process is initiated. Number of AODV optimizations are proposed in literature.

In following discussion important GPS based AODV optimizations are discussed.

5.4.1 Related work

For position based routing, use of GPS location information to improve routing

in MANET’s seems an attractive option because of availability of low-cost GPS

receivers. Number of GPS aided routing protocols and techniques proposed in

literature to improve routing in particular and overall performance of MANET’s.

Important position based routing protocol called location aided routing (LAR) is

proposed in [32]. Using location information obtained using services like GPS,

LAR reduces control overhead by limiting the network area into small request

zones and estimated zones. Study in [93] proposes GPS enhanced AODV routing

protocol called GeoAODV. GeoAODV is based on GPS and assumes that partic-

65


ipating nodes in a network can acquire, trck and exchange location information

accurately. GeoAODV uses GPS location information to limit the route discovery

mechanism. There is a routing table consisting entries like GPS coordinates, IP

address and geo life time is maintained at each node in a network. GeoAODV lim-

its the route discovery in to predicted search region using obtained GPS location

information. Apart from IP addresses of source and destination, RREQ carries

GPS coordinates of source and destination nodes along with calculated flooding

angle. Based on value of flooding angel and geo life time value search region and

freshness of destination coordinates are defined. If coordinates of destination node

are not known then, source node sets maximum value of flooding angle and floods

RREQ into whole network. At intermediate nodes, decision of forwarding RREQ

depends on that nodes presence in particular search region. Authors in [34] pro-

posed a GPS enhanced AODV routing protocol called GBAODV for VNET. This

method Separates traffic simulation and network simulation. Two main features

apart from AODV,

• The node receiving an RREQ packet will check the distance and motion

trend between the precursor and itself, to decide if this RREQ should be

broadcasted.

• Marking route according to the position and velocity of the source, interme-

diate and destination.

Another GPS based AODV optimization called EL-AODV is proposed in [94].

This work proposes an expanding Ring prediction and location aided AODV rout-

ing algorithm. Using GPS information obtained, this algorithm improves process

of route discovery and route maintenance in conventional AODV. During route

discovery process, sending of RREQ is controlled by predicting expanding ring

topology and during route maintenance, algorithm predicts the motion range of

destination node to avoid blind routing. When link breaks, upstream node for-

cast the motion range of destination node and send RREQ in to predicted area

to mend the broken path. Study in [95] show how GPS can be used to obtain

the location of the node and this information is exchanged when node wanted to

66


transmit the packet. Author in [96] proposes new technique to reduce overhead

during route discovery phase of conventional AODV. In proposed optimization,

using geographic information and average speed of destination node, source node

computes expected zone in circular shape to send RREQ. Work in [97] uses direc-

tional flooding using coordinates to improve AODV. In this protocol, intermediate

nodes forwards RREQ based on polar coordinate system computations. Nodes are

considered as poles and destinations node are as a point on same plane. With the

help of GPS information, polar axis of all nodes is fixed towards north direction.

Azimuth angle is calculated between geographic north and vector from source

node position to destination node position. Whenever source has data packet to

send, it calculates azimuth between geographic north and vector from source to

destination which ultimately decides the search limit. Intermdediate nodes refers

to azimuth anlge while forwarding the RREQ message.

5.4.2 Conventional AODV versus GPS aided AODV

We have modified routing table of AODV, now route entry for particular desti-

nation also consist GPS location of next hope in a route, distance to next hope,

minimum transmission power required to transmit the packet to next hope and

GPS information of destination node. The distance between various nodes is cal-

culated using Haversine equation as explained in the following subsection. The

value of transmission power is calculated using the energy model proposed in the

following section. Control packets (including RREQ, RREP and RERR) in GPS

aided AODV are modified to include GPS locations along with addresses of the

source and destination nodes (figure 5.5 and figure 5.6). The process of updating

and maintening the latest routes is the same as conventional AODV. Whenever

source node does not have route entry of intended destination node it broadcast

RREQ as in conventional AODV. Upon reception of RREP node follows the

proposed method of route formation.

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Figure 5.5: RREQ Packet Format

Figure 5.6: RREP Packet Format

5.4.3 Working of GPS aided AODV

Operation of GPS aided DSR consist three distinct phases, path setup, route

discovery and route maintenance. When source node has destination GPS address

in its routing table, path setup process is initiated. In a case when there is no

GPS information available source node initiates route discovery process. Whenever

source node (i) has data to send to the destination node, it looks for route entry to

destination in its routing table. If source node has route entry and route sequence

number is not too old then it follows algorithm1 otherwise, it starts route discovery

process as explained in algorithm2. Here it is to be noted that each node keeps

the update of GPS location of all nodes in its transmission range.

Algorithm1: When the node has GPS location of the destination node.

1. Calculate distances from neighbors to destination node.

2. Compare these distances to find out the minimum reachable distance to the

destination node.

3. Calculate minimum power transmission value to reach the neighbor having

minimum reachable distance to the destination node

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Figure 5.7: AODV - Route formation process

4. Send data packet to a neighbor having a minimum distance to a destination

with the calculated value of transmission power.

Algorithm2: When GPS location is not available.

1. Broadcast RREQ using traditional AODV protocol.

2. Find GPS location of destination node using RREP received from the desti-

nation node.

3. Follow the process in algorithm1 to find the shortest route to the destination.

When the source node has GPS location of destination node in its routing table

the process of route setup is easy and less complex. The process of route setup

is explained using example in figure 5.7. Let node i is source node and node j is

destination node. Say if node i has data to send then it looks that neighbor among

node k, n and o who is nearer to node j using Haversine formula and GPS locations

of respective nodes. Node i finds node o has minimum distance to node j. Now

node i calculates the value of the minimum transmission power to reach node o

and transmits the data packet to node o using the calculated value of transmission

power. Node o will follow the same process and transmit the data packet to node

m. The process continues until data packet reach to node j. The process of path

setup and route discovery (if GPS location of destination node is not available) is

explained using flow chart shown in figure 5.8. Flow chart in figure 5.9 explains the

route maintenance process. In proposed scheme the process of route maintenance

is done by intermediate node where route is broken. In a case when route breaks,

intermediate node finds a neighbor node who has minimum distance to destination

69


Figure 5.8: AODV - Route setup process

by comparing GPS locations. The process of selection of neighbor as next node in

a route is same as process followed during path setup process. The advantage of

this method is that it reduces generation of control overhead and limits frequent

route discovery process required to find alternate routes to destination. It also

reduces processing time spent during route maintenance process. If intermediate

node can not find alternate route, then it sends RERR message to source node.

Upon reception of RERR route discovery process is initiated by source node.

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Figure 5.9: AODV - Route maintenance process

5.5 GPS aided DSR

In this section, proposed GPS aided dynamic source routing (DSR) is discussed. As

discussed in previous chapter DSR is on-demand source routing routing protocol.

Conventional DSR uses global flooding during the route discovery process and for

periodic beacons. DSR Learns and stores new routes during route discovery and

data exchanges in route caches. DSR uses source routing concept, i.e. source

node constructs the whole path to the destination in the packet header and packet

71


follow that path to travel from source to destination. As shown in figure 5.10

packet header may consist route: N2 – N4 – N7 – N8. In proposed optimization,

route discovery and maintenance process of basic DSR is optimized using GPS

location information of nodes. We have used the concept of (1) controlled flooding

during route discovery process and (2) variable transmission power based on the

distance between two nodes. Route maintenance is now at the local level. In case

of the route breaks, adjacent nodes find the alternate node for a prescribed route

in packet header using GPS location information of its neighbors.

Figure 5.10: Packet flow - Basic DSR

5.5.1 Related Work

Numbers of optimizations are proposed in order to improve the operation of DSR

specifically the route discovery and maintenance process. In [4] author proposed

a dynamic source routing technique for ad hoc networks combined with network

location awareness. Whenever node has a data packet for a particular destination

it computes graph G representing the current network topology from its location

table. Then it locally applies a centralized algorithm for the determination of a

minimum cost path to the destination. Total cost represents the total number of

intermediate hops to be traversed by a data packet to reach the destination. The

author in [98] proposed a dynamic source routing discovery optimization protocol

based on the GPS system. Optimized protocol is based on GPS screening angle in

which nodes take the forwarding decision based on the angle between the previous

node, itself and the next node. This work shows the GPS screening angle has a

72


profound impact on reducing the number of route queries and therefore it reduces

control overhead. In [32] author proposed LAR (Location-Aided Routing) proto-

col. LAR is developed from DSR which uses geographical location information like

GPS in order to predict the location of the node. The LAR protocols use location

information to reduce the search space for the desired route. LAR divides net-

work area into expected and request zones during the process of route formation.

Limiting search space results in fewer route discovery messages which ultimately

results in decreased control overhead. The work in [99] propose a Dynamic Source

Routing Discovery Optimization Protocol using the GPS system. This technique

is based on GPS screening angle where. nodes takes the forwarding decision based

on the angle between the previous node, itself and the next node. This work

shows GPS screening angle has a profound impact on reducing the number of

route queries. Author in [32] proposed LAR (Location-Aided Routing protocol)

protocol. This protocols is developed from DSR which uses geographical location

information like GPS in order to predict the location of the node. Main difference

form DSR is that it attaches GPS information with the packet to find end to end

routes. Study done in [96] proposed GPS assisted overhead reduction technique

in which LAR is modified. In this work authors focused on the forwarding zone

modification to overcome the misdirection flooding problem inspired by DREAM

protocol. Author in [33] proposed a routing protocol called PLAR for mobility

models in which target motion is known. In this work LAR (Location-Aided

Routing) is modified to use GPS information to predict the probable location of

the destination node. It uses the concept of request zone to find destination node

if it’s GPS location known to the source. Study in [98] proposes GPS based route

discovery optimization scheme called GDSR. GDSR is reactive routing protocol

that combines DSR and GPS. In GDSR RREQ is forwarded only to the nodes

that are further away from the query source. GDSR is based on the GPS screening

angle where the nodes takes the forwarding decision based on angle between the

previous node, itself and the next node. When the route request is unable to reach

a destination, the source times out waiting for the route reply and it restarts the

route discovery for the same destination.

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5.5.2 DSR versus GPS aided DSR

The main difference between DSR and GPS aided DSR is that in proposed opti-

mization data packet does not carry complete end to end path in its packet header.

Instead of whole path data packet carries GPS location information of destination

node. Proposed technique take advantage of conventional DSR’s efficient mecha-

nism to acquire and store locations of node during data exchanges. Route cache

of all nodes in a network is modified to store GPS information of all active nodes

in a network. GPS information is updated during data exchange, route discovery

process. Other difference is that sending node transmits a packet with variable

transmission power based on calculated distance to receiving node. Transmitting

node also considers relative motion of receiving node while forwarding the data

packet to that node. Another important feature of proposed technique is use of

controlled flooding during route discovery process.

5.5.3 Working of GPS aided DSR

If source node has data to send to destination node, it looks for route entry to the

destination in its route cache. If source node has GPS location of destination in its

route cache, then it follows algorithm 1 otherwise it starts route discovery process

as explained in algorithm 2. Here it is to be noted that each node keeps the

update of GPS location of all nodes in its transmission range. Upon reception of

RREQ intermediate node follows the steps given in algorithm 3. These algorithms

are discussed in following sub-sections.

Algorithm 1: When node has GPS location of destination node.

1. Calculate distances from neighbors to the destination node.

2. Compare these distances to find out the minimum reachable distance to the

destination node.

3. Calculate minimum power transmission value to reach the neighbor having

a minimum reachable distance to the destination node.

74


4. Send data packet to a neighbor having a minimum distance to a destination

with the calculated value of transmission power.

Algorithm 2: When GPS location is not available.

1. Send RREQ to all neighbors with one hop count.

2. Wait for RREP equal to one hope count.

3. If counter expires, increase hop and send again to all neighbors.

4. Wait for RREP until set hop count expires.

5. Increase hop counts and repeat the process until RREP is received.

Algorithm 3: When RREQ received at intermediate node.

1. Check duplication of RREQ, if ok follow step 2 else discard RREQ.

2. Look for GPS location of destination node specified in RREQ from route

cache.

3. If it has GPS location of destination node send RREP consisting GPS loca-

tion of a destination to the source node.

4. If GPS location is not available, check hop count.

5. If hop count alive, forward RREQ to all neighbors else remain silent.

When there is GPS location of destination node with source node, the process

of forwarding data packet is very easy using proposed method. The process of

selection of shortest end to end route is explained using example network in figure

5.11, let N0 and N9 are source and destination nodes respectively. Whenever

N0 has data packet for N9, it looks into route cache to find GPS location of

N9. Assuming that GPS location is available, N0 will follow two steps. First, it

calculates the distance to N9 from its neighbors N1, N3 and N4 (nodes within

transmission range) to find neighbor node nearest to the destination. Second N0

75


Figure 5.11: Forwarding data packet

finds its distance to the node selected in the first step to select an appropriate

level of transmission power. Nodes along green line are selected to form the route

from N0 to N9. Red lines show nodes within transmission range of the particular

node. In this example, N0 finds that N4 has minimum or shortest distance to

N9 compared to N1 and N3. Therefore N0 will transmit the data packet with

appropriate transmission power to N4. N4 follows the same process and transmit

the data packet to N6. N6 will transmit the data packet to N9 using following the

same process. In this process, intermediate nodes check the destination address

in a packet header to know whether it itself is destination node or not. If an

intermediate node is not destination node then it compares its neighbors with

GPS location in a packet header to find next node in a route. The process of

route formation can be understood using flow chart in figure 5.12.

Flowchart in figure 5.13, explains route discovery process if GPS location of the

destination node is not available. In this case, the source node sends RREQ

(consists of location information of all its neighbors) to all neighbors with one hop

count and waits for a reply. Upon receiving RREQ, node searches own route cache

to find GPS information related to the destination listed in RREQ packet. If GPS

information of the intended node is available, then it replies to the source node if

note then remains idle. Source node waits for acknowledgment up to one hop time

76


Figure 5.12: DSR - Route setup process

and forwards the same RREQ again to same neighbors and increases hop count

by two. At this time (for increased node counter) neighbors check hop counts and

forwards it to next neighbors (that are not listed in RREQ packet (listed nodes are

known and no need to check again), these limits duplicate transmission of RREQ

packet) since hop count is still alive. This process continues until GPS information

of destination node is available to a source node. This results in limited flooding

into the limited area around the source node. It is noted that whenever node

forwards RREQ to next node it attaches location information it has into RREQ

so that next receiving nodes may update the route cache. The route maintenance

process is same as explained in previous section. Intermediate node where route

breaks finds alternate route to destination. If no alternate route is available then

intermediate node sends RERR to source node.

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Figure 5.13: DSR - Route Discovery process

78

CHAPTER 6

Simulation & Performance Analysis

6.1 Introduction

As discussed in chapter − 1, variety of tools available for wireless ad-hoc network

simulation. Examples of important networks simulation tools are NS-2 (Network

Simulator 2), NS-3 (Network Simulator 3), OPNET, OMNeT++, NetSim, REAL,

QualNet, J-Sim. These simulators offer distinct simulation features with a variety

of different scenarios. Now a days NS-2 and NS-3 simulators are very famous

among researchers because of its wide support to almost all real time scenarios

and protocols in wireless ad-hoc networks. These two simulators are open sources

and freely available on the internet for educational and research purpose. In order

to validate and check the credibility of proposed research, the NS-3 simulation

tool is used. The NS-3 network simulator provides a discrete-event environment

with different inbuilt models and protocols. We have used NS-3.25 version of the

tool with different input parameters. Trace files (∗.tr) of NS-3.25 are analyzed to

calculate the values of performance metrics.

6.2 Simulation Parameters

Set of simulations are performed by varying various parameters to check the suit-

ability of proposed routing optimization. The overall performance of ad-hoc net-

works can be affected by a variety of factors. To account most of the factors we

have used and created different realistic approaches and scenarios. The simulation

time is 100 seconds for each set of simulation with a network area of 300X1500m.

79

CHAPTER 6. SIMULATION & PERFORMANCE ANALYSIS

For conventional ADOV and DSR simulation we have used fix value of transmis-

sion power, whereas for GPS aided AODV and DSR dynamic value of transmission

power is used. We have kept length of data packet to minimum value at 64 byte

keeping the size of network in view. Node speed is kept constant at 20 ms and

can be set as required for future simulations. Other relevant parameters are listed

table 6.3.

Parameter Value/TypeNumber of Nodes 10, 20, 30, 40, 50, 100Total Simulation Time 100 secondsData Packet Length 64 BytesData Rate 2048 bpsNetwork Area 300 x 1500 mPropagation Delay Model Constant SpeedPhysical Standard IEEE 802.11bTransmit Power VariableNode Speed 20 msPause Time 0 ms

Table 6.1: Simulation Parameters

6.3 Simulation metrics

To measure the suitability of proposed technique, different packet level metrics are

used [100]. Performance metrics used are Transmission Power, Energy consump-

tion, Throughput, Packet Delivery Ratio, End-to-End Delay, Normalized Routing

Load, Packet Loss and Jitter which is the time variation in the arrival of consec-

utive packets at the receiver. Jitter is the result of variable path lengths, traffic

route availability, etc. Flow−monitor output of NS3 calculates jitterSum auto-

matically. Average jitter calculations are based on an analysis of flow −monitor

output file. To obtain value of each performance metric, we have kept all simula-

tion parameters constant except number of nodes which are varies in the sets of

10, 20, 30, 40, 50 and 100.

End to End Delay (EED) is average time taken by packets to reach the destina-

tion in seconds. It combines time required to process data packet at intermediate

nodes and traveling time. The low value of EED indicates the shortest routes

80


with lower load and processing time. End to end delay can be increased by select-

ing shortest end to end path in terms of distance and intermediate hops. EED

is calculated by taking simulation time difference between transmission (tt) and

reception (rt) of a particular packet.

EED = tt

rt(6.1)

Normalized Routing Load (NRL) is defined as the number of routing (control)

packets transmitted per data packet sent to the destination. It measures the

effectiveness of routing protocol in terms of generation of extra load to exchange

and update routing information among the nodes in a network. It also accounts

control packets exchanged during route establishments. NRL is the ratio of routing

packets (rp) and total data packets transmitted pt.

NRL = rp

pt(6.2)

Transmission Power refers to the amount of power required to transmit a data

packet. Value of transmission power depends on transmission range. For given

distance between node i and j, transmission power is calculated using equation

5.6. Average power consumption per data packet transmission is calculated by the

averaging total power to the number of data packets transmitted during simulation

time.

Pti,j = mNβ

Pli,j m

√Γ(m+ 1)O∗i,j

(6.3)

Energy consumption accounts power consumption during data transmission

plus processing at transmitter and receiver circuitry. Energy consumption is an

important metric to indicate a lifetime of the network. Energy consumption is

calculated from equation 5.7.

81


Eb = Pti,j + PTX + PRXRb

(6.4)

Throughput (TP ) is average successful transmission the rate in kbps. It indi-

cates rate of successful transmission of data packets from various source to respec-

tive destination nodes in a network. It gives an idea about number of packets lost

due to link failure and network congestions. It is calculated as the ratio of total

bytes received (tbr) to simulation time difference between the last packet received

(lpr) and the first packet transmitted (fpt).

TP = tbr

lpr − fpt× 8

1000 (6.5)

Packet Delivery Ratio (PDR) gives a number of transmission attempts per

packet received. It indicates the stability of end to end routes formed if routes are

inefficient there are more number of attempts required by the sender to send packet

successfully. PDR is the ratio between the received packets by the destination

and the generated packets by the source.

PDR = pt

pr(6.6)

Packet Loss (PL) is a measure of a number of data packets actually received at

the receiver. PL is a difference of total data packets transmitted (pt) and total

packets received (pr). The data packet may be lost due to link failure, buffer

overflow, looping, retransmissions, buffer overflow, etc. It is calculated as the

difference between total packets transmitted and total packets received successfully

during simulation time from equation (6.7).

PDR = pt− pr (6.7)

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6.4 GPS Aided AODV

This section discusses simulation results obtained for GPS aided AODV and con-

ventional AODV for different input parameters and performance metrics. The

graphs showing red dotted line indicates conventional AODV whereas Black solid

line refers to proposed GPS aided AODV.

6.4.1 Power Consumption V/S number of nodes

• Observations (figure 6.1):

– GPS aided AODV has 42% less power consumption in terms of Watt-

hour.

– Up to 30 nodes the average power consumption is 14 and 9 watt hour

for AODV and GPS aided AODV respectively.

– For nodes greater than 40, the average is 103 and 57 watt hour for

AODV and GPS aided AODV respectively.

Figure 6.1: Power Consumption v/s increasing nodes

83


6.4.2 Energy Consumption V/S number of nodes


– Total energy consumption is 52% less for GPS aided AODV compared

to traditional AODV.

– For nodes up to 30 the average energy consumption is 53 and 30 joules

whereas above 30 nodes the average value is 496 and 231 joules for

AODV and GPS aided AODV.

Figure 6.2: Energy Consumption (Joules) v/s increasing nodes

6.4.3 End to End delay V/S number of nodes


– The effect of the shortest path can be seen from the graph in the form

of E2E delay.

– Average end to end delay improvement is approximately 55% for GPS

aided AODV compared to conventional AODV.

– Less end to end delay also contribute to minimizing energy consump-

tion.

84


– For low node density, large E2E due to the availability of limited end

to end routes.

– GPS aided AODV performs better due to selection of shorter end to

end routes compared to conventional AODV.

Figure 6.3: End to End delay v/s increasing nodes

6.4.4 Normalized Routing Load V/S number of nodes


– Control flooding and route maintenance at local level limit the genera-

tion of routing packets.

– Large number of control packets consumes bandwidth and reduces rout-

ing efficiency.

– As we can see from graph average control packets per data packet are

2 and 3 respectively for GPS aided AODV routing and conventional

AODV.

– Overall there is 33% less control overhead in case of proposed GPS

aided AODV protocol.

– Generation of low control overhead for GPS aided AODV is due to

controlled flooding and optimized route maintenance strategy.

85


Figure 6.4: Normalized Routing Load v/s increasing nodes

6.4.5 Packet Delivery Ratio V/S number of nodes


– From the graph we can observe that more packets are dropped when

density of nodes is less and when traffic or load is high.

– For medium node density packet delivery success is 86.25% and 78.25%

respectively for proposed optimization compared to AODV protocol.

– In proposed optimization, selection of strong route (Mobility modeling)

and route maintenance mechanism is at node level (where route breaks)

is the reason to have 10% better performance compared to conventional

protocol.

6.4.6 Throughput V/S number of nodes


– Nodes less than 40 routes availability to the destination and are more

prone to break due to fact nodes are spread across transmission and

discovery range of each other.

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Figure 6.5: Packet Delivery Ratio v/s increasing nodes

– For nodes greater than 40 to 100 throughput is stable in the range of

165 Kbps since the density of nodes increases results in easy and strong

route availability.

– The throughput comparison shows that GPS aided AODV performed

better in terms of delivery of data per unit time due to controlled packet

loss during route maintenance.

6.4.7 Result Summary - AODV

Parameter AODV GPS aided AODV ImprovementEnergy Consumption (Joule) 342.95 146.63 57%End to End Delay (ms) 1.43 0.77 46%Normalized Routing Load 3.68 2.41 34%Throughput (Kbps) 99.41 105.14 6%Packet Delivery Ratio 0.70 0.76 9%

Table 6.2: GPS aided AODV Versus AODV

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Figure 6.6: Throughput v/s increasing nodes

6.5 GPS Aided DSR

This section discusses simulation results obtained for GPS aided DSR and conven-

tional DSR for different input parameters and performance metrics. The graphs

showing red dotted line indicates conventional DSR whereas Black solid line refers

to proposed GPS aided DSR. Values on X−axis indicates a number of nodes and

Y − axis indicates respective performance metrics.

6.5.1 Power Consumption V/S number of nodes


– Power consumption for GPS aided DSR is 22

– Up to 30 nodes the average power consumption is 10 and 6 watt hour

for DSR and GPS aided DSR respectively.

– For nodes greater than 40, the average is 76 and 62 watt hour for DSR

and GPS aided DSR respectively.

88


Figure 6.7: Power Consumption v/s increasing nodes

6.5.2 Energy Consumption V/S number of nodes


– Overall GPS aided DSR performs 30

– For nodes less the average energy consumption in joule is 41 and 21,

for nodes greater than 30 the values are 420 and 299 for conventional

DSR and GPS aided DSR respectively.

Figure 6.8: Energy Consumption (Joules) v/s increasing nodes

89


6.5.3 End to End delay V/S number of nodes


– It is average time taken by packets to reach the destination in seconds.

– It is simulation time difference between transmission and reception of

the particular packet.

– The average value for GPS aided DSR is 0.60 ms and for DSR is 0.86ms.

Figure 6.9: End to End delay v/s increasing nodes

6.5.4 Normalized Routing Load V/S number of nodes


– GPS aided DSR transmits 1.4 control packets per data packet, whereas

traditional DSR transmits 11 control packets for 5 data packets.

– GPS aided DSR avoids global flooding during the route discovery pro-

cess and uses route maintenance at the local level.

– It is to be noted that a number of hopes increases in a route, control

packets also increases.

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Figure 6.10: Normalized Routing Load v/s increasing nodes

6.5.5 Packet Delivery Ratio V/S number of nodes


– Both DSR and GPS aided DSR are able to deliver most of the packets

transmitted.

– On an average packet loss in GPS aided DSR is 3% less compared to

DSR.

– Beyond 70 nodes approximately 3% packets got lost for GPS aided DSR

and in DSR value is approximately 5%.

– GPS aided DSR is able to deliver more packet because of selection of

more reliable and shorter routes to destination.

6.5.6 Throughput V/S number of nodes


– Average successful transmission rate in kbps.

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Figure 6.11: Packet Delivery Ratio v/s increasing nodes

Figure 6.12: Throughput v/s increasing nodes

– It is the ratio of total bytes received to simulation time difference be-

tween last packet received and the first packet transmitted.

– Average value for GPS aided DSR is 120.40 Kbps and for DSR is 91.90

Kbps.

– Here, GPS aided DSR perform better in terms of delivery of data per

unit time due to controlled packet loss during route maintenance.

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6.5.7 Result Summary - DSR

Parameter DSR GPS aided DSR ImprovementEnergy Consumption (Joule) 230.24 160.35 30%End to End Delay (ms) 0.45 0.16 64%Normalized Routing Load 2.22 1.40 36%Throughput (Kbps) 76.58 100.33 31%Packet Delivery Ratio 0.96 0.98 2%

Table 6.3: GPS aided DSR Versus DSR

6.6 GPS aided AODV v/s GPS aided DSR

In this section GPS aided AODV is compared with GPS aided DSR. Compar-

ative analysis in section 6.5 and 6.4 is between conventional routing protocols

and proposed GPS aided optimizing technique. Whereas in this section we have

done comparative analysis to find which protocol (AODV or DSR) performs bat-

ter with GPS aided routing technique. We have compared GPS aided AODV and

DSR interms of end to end delay, normalized routing load, throughput and en-

ergy consumption. As indicated in legends, Red dotted lines are used for AODV

and Black solid lines are used for DSR. Table 6.4 gives comparative summary of

performance of GPS aided AODV and GPS aided DSR. Energy consumption for

important routing protocols (table 6.5) shows GPS aided routing performs better

due to dynamic transmission power strategy. In conventional routing protocols

like AODV, DSR, DSDV AOMDV etc., the value of transmission power is fixed

and does not depends on transmission range. This causes several issues like signal

interference for networks with high node density and extra power consumption.

It is clear that GPS aided routing can perform better if more parameters like

mobility, available battery power with node is considered.

Parameter GPS aided AODV GPS aided DSREnd to End Delay (ms) 0.77 0.16Normalized Routing Load 2.41 1.40Throughput (Kbps) 105.14 100.33Energy Consumption (Joule) 146.63 160.35

Table 6.4: GPS aided AODV Versus GPS aided DSR

93


Routing Protocol Energy Consumption (Joule)GPS aided AODV 146.63GPS aided DSR 160.35AOMDV 254.65DSDV 190.68

Table 6.5: Energy Consumption Proposed versus other routing protocols

6.6.1 Summary

It is evident from results obtained that GPS aided routing performs better com-

pared to conventional AODV and DSR. From figure in section 6.4 and 6.5, it

is observed that GPS aided DSR has edge over GPS aided AODV. Comparing

performance in terms of energy consumption, it is found that GPS aided DSR

consumes 13.72 Joule of more energy during simulation time. End to end delay

comparison shows on an average packets in GPS aided DSR reaches destination

by taking 0.61 ms less time compared to GPS aided AODV. Comparative result of

NRL shows that GPS aided AODV generates more control head per data packet.

GPS aided DSR generates one less control per data packet. Throughput perfor-

mance shows that GPS aided AODV has a fractional edge over GPS aided DSR.

It can transfer 5 kbps more data compared to GPS aided DSR. PDR performance

of GPS aided DSR is around 98 % whereas that of GPS aided AODV is around

76 %. Here GPS aided DSR delivers 22 % more packets compared to GPS aided

AODV during simulation time. Comparison with other routing protocols confirms

that GPS aided routing can play important role to increase routing efficiency.

94

Conclusion

The aim of the thesis work is to optimize MANETs routing process using GPS

aided technique. We have proposed power efficient GPS aided routing technique

which uses GPS location information of nodes to find the shortest end to end routes

and calculates transmission power based on distance to receiving node. GPS aided

AODV and DSR are tested using simulation tool NS-2.25 by increasing network

load in terms of number of nodes in the fixed geographical area. Simulation of

proposed technique with AODV shows that there is approximately 42% saving in

average battery power consumption and average end to end delay is improved by

55% compared to conventional AODV during simulation time. Whereas simulation

with DSR shows there is approximately 29% saving in total energy consumption

and average end to end delay is improved by 30% compared to conventional DSR

during simulation time. GPS aided routing is able to perform better in terms of

throughput, normalized routing load, packet delivery ratio compared to conven-

tional routing techniques. It is observed from results that proposed GPS aided

routing technique is more suitable with DSR compared to AODV in terms of end to

end delay and normalized routing load whereas GPS aided AODV performs better

in term of throughput and energy consumption. Overall, result analysis indicates

that GPS aided position based routing is a better option compared to conven-

tional routing approach. Comparison of energy consumption during simulation

time with other routing protocols such as DSDV and AOMDV also confirms that

GPS aided routing plays an important role to improve energy efficiency. With

precise selection of parameters like mobility and traffic, the routing can be im-

proved further. Energy consumed by GPS enhanced receiver can be compromised

due to the availability of advanced, precise and energy saving GPS enabled mobile

handsets.

95

Future Work

Proposed GPS aided routing can be implemented and tested on hardware. The

technique can be tested for more complex parameters like mobility, coverage area,

network load, coverage area etc. Route discovery process can be further im-

proved by optimized data sharing techniques like controlled flooding. More precise

method of exchanging latest GPS information among nodes. Battery life of node

can be increased by introducing advance hardware circuitry.

96

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Publications

1. ”GPS Aided AODV routing protocol for MANET”, Optical and Wireless

Technologies, Lecture Notes in Electrical Engineering 472, pp 585-598, ISBN

9789811073946, February 2018, Springer, Singapore, (UGC Approved Jour-

nal)..

2. ”Power Efficient GPS Aided DSR in MANETs”, International Journal of

Computer Networks and Wireless Communications (IJCNWC), ISSN: 2250-

3501, Vol. 7, No. 6, Nov-Dec 2017, (UGC Approved Journal).

3. ”Comparative Analysis of Routing Protocols for MANET using Packet Level

Diagnostic Metrics”, International Journal of Engineering Trends in Elec-

trical and Electronics (IJETEE - ISSN: 2320 - 9569), Vol. - 11, Issue - 4,

August-15.

4. ”GPS Aided Power Optimization in MANETs”, International Journal of

Modern Electronics and Communication Engineering (IJMECE) ISSN: 2321-

2152, Volume No.-6, Issue No.-5, September, 2018, (UGC Approved Jour-

nal).

5. ”GPS Aided Power efficient Dynamic Source Routing in MANETs”, IOSR

Journal of Engineering (IOSRJEN), ISSN (e): 2250-3021, ISSN (p): 2278-

8719 Vol. 08, Issue 9 (September. 2018), V (III), PP 46-52 (UGC Approved

Journal).

108

Appendix A

NS-3 Implementation (Important Classes)

Class Description

ns3::GeographicPositions It Consists of methods dealing with Earth geo-graphic coordinates and locations.

ns3::MobilityModel Keep track of the current position and velocity ofan object.

ns3::YansWifiPhy

It implements a model of 802.11a. Attributes de-fined in parent class ns3::WifiPhy includes, Maxi-mum available transmission level, Minimum avail-able transmission level, Number of transmissionpower levels available between TxPowerStart andTxPowerEnd.

ns3::DeviceEnergyModel

This class helps to create and install device energymodel onto NetDevice. A device energy model isconnected to a NetDevice (or PHY object) by call-backs. Note that device energy model objects arenot aggregated onto the node. They can be ac-cessed through the energy source object, which isaggregated onto the node.

ns3::NetDevice

It covers both the software driver and the simu-lated hardware. A net device is “installed” in aNode in order to enable the Node to communicatewith other Nodes in the simulation via Channels.Like in a real computer, a Node may be connectedto more than one Channel via multiple NetDevices.The NetDevice class provides methods for manag-ing connections to Node and Channel objects.

ns3::Ipv4AddressHelper

This class is a very simple IPv4 address generator.It has no notion that IP addresses are part of aglobal address space. Ipv4AddressHelper is a sim-ple class to make simple problems easy to handle.

ns3::Ipv4RoutingProtocol

Defines two virtual functions for packet routingand forwarding. The first, RouteOutput(), is usedfor locally originated packets, and the second,RouteInput(), is used for forwarding and/or deliv-ering received packets. Also defines the signaturesof four callbacks used in RouteInput().

109

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