Efficient Use Of Power And Energy Computer Science Essay

Published Date: 02 Nov 2017

DEPARTMENT OF INDUSTRIAL SYSTEMS ENGINEERING

Exploration of Routing Protocols with

Efficient Use of Power and Energy

in Mobile Ad Hoc Networks

PRAMOD MANGATHA

This dissertation is submitted in partial fulfillment of the requirements

for the award of the Bachelor of Engineering Degree in

Telecommunications.

Supervisor: . . . . . . . . .

April 2013

SCHOOL OF INNOVATIVE TECHNOLOGIES AND ENGINEERING

DEPARTMENT OF INDUSTRIAL SYSTEMS ENGINEERING

Plagiarism Agreement Form

I hereby declare that the intellectual content of this thesis is the product of my own

work and that, to the best of my knowledge and belief, it contains no material previ-ously published or written by another person nor material which has been accepted

for the award of any other degree or diploma of the University or any other institute,

except where due acknowledgement and references are made in the text.

Candidate’s Name: MANGATHA Pramod

Candidate’s Number: BTEL/09/FT/091608

Programme/Year: BEng (Hons) Telecommmunications ‘09

Project Title: Exploration of Routing Protocols with Efficient Use of Power and

Energy in Mobile Ad Hoc Networks

Signature: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Date: April 13, 2013

i

Abstract

The Thesis Abstract is written here (and usually kept to just this page). The page

is kept centered vertically so can expand into the blank space above the title too. . .

ii

Acknowledgements

The acknowledgements and the people to thank go here, don’t forget to include your

project advisor. . .

iii

Table of Contents

Plagiarism Agreement Form i

Abstract ii

Acknowledgements iii

Table of Contents iv

List of Figures vii

List of Tables viii

1 Introduction 1

2 Problem Identification 4

2.1 Challenges in MANET . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.2 Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.3 Energy and Power Efficiency . . . . . . . . . . . . . . . . . . . . . . . 5

2.4 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 Project Management 7

3.1 Scope of Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.2 Project Milestones . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.2.1 Project Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.2.2 Research / Literature Review . . . . . . . . . . . . . . . . . . 8

3.2.3 Algorithm Development & Testing . . . . . . . . . . . . . . . 8

3.2.4 Results & Discussion . . . . . . . . . . . . . . . . . . . . . . . 9

3.2.5 Final Report . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.3 Work Breakdown Structure . . . . . . . . . . . . . . . . . . . . . . . 9

3.3.1 WBS Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.3.2 WBS Dictionary . . . . . . . . . . . . . . . . . . . . . . . . . 11

iv

Table of Contents

3.4 Project Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

4 Literature Review 14

4.1 Mobile Ad Hoc Networks . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.1.1 History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.1.1.1 1st Generation . . . . . . . . . . . . . . . . . . . . . 14

4.1.1.2 2nd Generation . . . . . . . . . . . . . . . . . . . . . 15

4.1.1.3 3rd Generation . . . . . . . . . . . . . . . . . . . . . 15

4.1.2 Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.1.3 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.2 Routing in MANETs . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.2.1 Classification of Ad Hoc Routing Protocols . . . . . . . . . . . 19

4.2.2 Pro-active Protocols . . . . . . . . . . . . . . . . . . . . . . . 22

4.2.2.1 DSDV . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4.2.2.2 HSR . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.2.3 Reactive Protocols . . . . . . . . . . . . . . . . . . . . . . . . 25

4.2.3.1 AODV . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.2.3.2 DSR . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4.2.3.3 LAR . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.2.4 Hybrid Protocols . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.2.4.1 ZRP . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4.3 Energy Efficient Routing in MANETs . . . . . . . . . . . . . . . . . . 27

4.3.1 Power Aware Metrics . . . . . . . . . . . . . . . . . . . . . . . 27

4.3.2 Energy-efficient Routing Protocols . . . . . . . . . . . . . . . . 27

4.3.2.1 Transmission Power Control . . . . . . . . . . . . . . 27

4.3.2.2 Load Distribution . . . . . . . . . . . . . . . . . . . 27

4.3.2.3 Sleep & Power-down . . . . . . . . . . . . . . . . . . 27

4.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

5 Project Progress 28

v

Table of Contents

References 29

vi

List of Figures

1.1 Infrastructure based network . . . . . . . . . . . . . . . . . . . . . . . 2

1.2 Ad-Hoc Wireless Network . . . . . . . . . . . . . . . . . . . . . . . . 2

2.1 Minimum Power Route . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.1 Work Breakdown Structure . . . . . . . . . . . . . . . . . . . . . . . 10

3.2 Project Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.1 Classification of Ad Hoc Routing Protocols . . . . . . . . . . . . . . . 20

4.2 Destination Sequenced Distance Vector Routing . . . . . . . . . . . . 22

4.3 Example of DSDV . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.4 HSR Clustering Scheme . . . . . . . . . . . . . . . . . . . . . . . . . 24

4.5 AODV Route Discovery . . . . . . . . . . . . . . . . . . . . . . . . . 26

4.6 AODV Route Maintenance . . . . . . . . . . . . . . . . . . . . . . . 26

4.7 DSR Route Discovery and Maintenance . . . . . . . . . . . . . . . . . 27

vii

List of Tables

3.1 WBS Dictionary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4.1 Applications of Mobile Ad Hoc Networks . . . . . . . . . . . . . . . . 18

4.2 Common Ad Hoc Routing Protocols . . . . . . . . . . . . . . . . . . . 21

4.3 Routing Table in DSDV . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.4 AODV RREQ Parameters . . . . . . . . . . . . . . . . . . . . . . . . 25

4.5 AODV RREP Parameters . . . . . . . . . . . . . . . . . . . . . . . . 25

viii

Chapter 1

Introduction

Over the past decades, the people’s living environments have been greatly influenced

by an emergence of mobile and wireless communications. This considerate expansion

in wireless communication networks is mainly due to the ever-growing availability of

next generation devices like PDAs, smartphones and other wireless devices. These

devices are getting less expensive, smaller and have got more power. Even home appli-ances are now being enhanced to achieve computing and communication capabilities.

The technological evolution towards a fully pervasive and ubiquitous environment led

to an alternative way to enable the communicating devices to create, organise and

administer a wireless network without a fixed infrastructure, known as a Mobile Ad

Hoc Network (MANET).

A Mobile Ad Hoc Network, or MANET, is a group of autonomous mobile nodes

that communicate in an ad hoc fashion, i.e., directly to each other

1

. Most of the

time, the mobile nodes carry out the routing functions in addition to their primary

task. The wireless nodes form a dynamic network for communication without util-ising any predefined infrastructure-based network (Figure 1.2). Conventional mobile

wireless networks, on the other hand, require a more organised and fixed infrastruc-ture for operation and maintenance (Figure 1.1). The self-administering capability

of MANETs promotes their utilization to a large range of applications ranging from

military tactical networks to Wireless Sensor Networks.

One important drawback of MANETs is the energy constraint of the mobile nodes.

The absence of any kind of infrastructure implies that the nodes are most of the time

deprived of fixed power sources. The devices need to make use of batteries or other

1

RFC 2501 - Mobile Ad Hoc Networking (MANET) : Routing Protocol Performance Issues and

Evaluation Considerations, January 1999.

1

Chapter 1. Introduction

Figure 1.1: Infrastructure based network Figure 1.2: Ad-Hoc Wireless Network

passive power sources for operation. The network lifetime of the Ad Hoc Network

depends largely on the efficient use of power and energy of the nodes. Routing of

data packets plays a crucial role in ad hoc networking as it is carried out by the

nodes which constitute the network. The routing algorithms need to be optimized to

consider the energy constraint of the mobile nodes without affecting the performance

of the network .

Developing energy-aware routing protocols for MANET has been subject to active re-search work for the past few years. The concept of power-aware metrics to determine

communication routes in MANETs were first introduced in the late 90’s (Singh et al.,

1998). These metrics, which were used in shortest-cost algorithms, were based on

power consumption of the batteries at the nodes. Since, a number of energy-efficient

routing algorithms or protocols have been proposed; Avudainayagam et al. (2003)

developed the DEAR protocol which exploits the fact that in practical MANETs,

not all devices are limited in energy. More recent protocols include the MEA-DSR,

which minimizes energy loss by reducing the rate of route discovery (Chettibi and

Benmohamed, 2009), and AFTE, an Adaptive Fuzzy Threshold Energy based rout-ing algorithm (Hiremath and Joshi, 2012). The main concern in designing routing

algorithms that make efficient use of power and energy remains the negative effect

on the network performance as a whole in terms of end-to-end delay, packet delivery

ratio or overall throughput.

2

Chapter 1. Introduction

This paper explores the protocols in mobile ad hoc networks that take the energy re-strictions of the nodes to perform the routing of data packets and eventually optimise

an existing algorithm to improve its energy-efficiency ability. Chapter 2 defines the

issue of energy-awareness in Mobile Ad Hoc Networks, overviews the different routing

mechanisms that are power and energy efficient and sets the aims & objectives of this

project. Chapter 3 describes the project planning details, including the scope , the

approach taken and the project schedule. Chapter 4 reviews the related work with

respect to Mobile Ad Hoc Networks; their origins, the existing routing mechanisms,

the energy consumption models of mobile nodes, and the energy-efficient protocols

that currently exist. This chapter also provides for an algorithmic study of those pro-tocols and lays ground for the development/optimisation of a power-aware algorithm

in Chapter 5.

The simulation set-up to test the performance of the algorithm in (... Software

...) is detailed in Chapter 6. This is then compared against the more conventional

routing protocols and the corresponding results are analysed. The last chapters of

this report discusses the directions for future work and concludes the paper with a

summary and a critical appraisal of the work carried out.

3

Chapter 2

Problem Identification

2.1 Challenges in MANET

Mobile Ad Hoc Networks present a number of advantages over traditional wireless

infrastructure-based networks in terms of cost, deployment and mobility. However,

MANETs face some important drawbacks due to their dynamic topology and energy

constraints. (Hoebeke et al., 2004, Taneja and Patel, 2007, Kumar and Mishra, 2012)

details some of the main challenges of ad hoc networks concerned with Routing,

Security & Availability, QoS, Inter-networking or Power Consumption.

2.2 Routing

The constantly changing topology of MANETs makes device discovery and addressing

even more difficult. Coupled with the energy limitations of the nodes, routing in

mobile ad hoc networks in an energy-efficient manner proves to be a major issue.

There have been a number of different routing protocols proposed for Mobile Ad Hoc

Networks throughout the years which are being standardised by the IETF. These pro-tocols follow different approaches and are classified in three main categories: Proac-tive, Reactive & Hybrid routing protocols.

1. Proactive routing protocols ensures that the nodes of the network contain up-dated route information all the time. This is enabled through constant exchange

of control information and changes in topology.

2. Reactive routing protocols set up routes only to the nodes they need to com-municate to. This method requires Route Discovery and Route Maintenance

procedures to correctly set up a link from the source node to the destination.

4

Chapter 2. Problem Identification

3. Hybrid routing protocols combine the positives of both proactive and reactive

mechanisms, e.g. keeping up-to-date routes for closer nodes and reactively set

up other routes with a higher hop count.

Independent of their design approach, each routing mechanism calculates an optimal

route to attain certain objectives : the least end-to-end delay, a lower number of hop

counts between source and destination, low network congestion or a higher network

lifetime. The latter, however, is of particular interest when considering the energy

factor while routing.

The network lifetime is the period of time from the instant the network is deployed

to that when it becomes non-functional. In MANETs, this particular instant occurs

at the failure of the first node and in this context, such failure would correspond to

energy levels dropping below a threshold level enabling communication. Keeping in

mind the limited resources available to devices in a MANET, the lifetime will most

certainly depend on how the energy of the nodes are managed and conserved.

2.3 Energy and Power Efficiency

The energy issue in Mobile Ad Hoc Networks can be tackled at two levels, namely:

1. By reducing the power consumption when the nodes are inactive. This is

achieved by enabling a Sleep or Power Down mode and usually require aMaster-Slave system, whereby the Master node is responsible for the coordinating the

communication tasks while the slaves remain idle and talks to the Master only

on regular time intervals to verify if they have been addressed or not.

2. On a more global scale, by managing the power consumption while the nodes

are in active communication. This objective can be attained either by having

a controlled Transmission Power or Load Distribution.

The transmission power will have a direct consequence on the range of communica-tion; a higher power will enable a device to communicate with a more distant one.

Even though this method lowers the hop count and end-to-end delay, it does imply

5

Chapter 2. Problem Identification

R

D

S

R

A

B

Route A

Shortest Route

Single Hop

Higher Power Consumption

Route B

Minimum Power Route

Higher Hop Count

Increased End-to-end Delay Figure 2.1: Shortest route vs Minimum Power Route in Mobile Ad Hoc Networks

a larger amount of energy spent for transmission. A load distribution approach aims

at balancing the power consumption of all the nodes by taking their energy levels

into consideration for routing. In other other words, the shortest route (hop count)

between two devices in a MANET may not necessarily represent the route with the

least energy usage (Figure 2.1).

2.4 Objectives

As it was mentioned in the previous section, there are basically two distinct ap-proaches to resolve energy conservation in Mobile Ad Hoc Networks. This paper will

focus on efficiently managing resources during active communication from a global

perspective. The two main objectives of this project are :

1. Perform an in-depth algorithmic study of the existing Routing Protocols in

Mobile ad hoc networks that make efficient use of Power and Energy. This

study aims at identifying the functions, techniques, strengths and weaknesses

of the algorithms on which the protocols are based on.

2. Propose an optimized routing algorithm that, not only provides for energy

and power efficiency, but also limits the negative effects its performance and

reliability.

6

Chapter 3

Project Management

3.1 Scope of Project

This project aims to explore the existing energy-efficient routing protocols in mobile

ad hoc networks and eventually develop such an algorithm using a different and novel

approach. Considering the time span allocated to the project and the complexity of

the task, the scope of this project would be restrained to :

1. Understand the basic functioning of Mobile Ad Hoc Networks:

• Origins

• Properties

• Applications

2. An in-depth review of the research related to MANETs concerned with the:

• Routing Mechanisms and Protocols

• Energy consumption of the nodes

• Protocols that make efficient use of power and energy

3. Perform an algorithmic study on those protocols in terms of:

• Route Discovery

• Route Maintenance

• Energy Conservation

4. Propose a new routing algorithm which is energy and power aware while main-taining an appropriate trade-off with the performance and reliability of the

algorithm.

7

Chapter 3. Project Management

5. Implement the algorithm using MATLAB in order to :

• Perform a simulation for both static and mobile environments.

• Collect data

• Compare and Analyse the results

3.2 Project Milestones

3.2.1 Project Plan

After defining the aims & objectives of the project, the first step is to break it down

into smaller tasks and develop a schedule. The project plan will serve as a guide for

working on the different phases of development during the 30 weeks time period.

Projected Completion date: October 2012, Week 1

3.2.2 Research / Literature Review

The literature review is a very important part of the project. The research will

allow to identify the previous and active contributions in researching Mobile Ad

Hoc Networks. This chapter will focus mainly on the existing energy-aware routing

protocols in MANETs and the performance of their algorithms.

Projected Completion date: December 2012, Week 3

3.2.3 Algorithm Development & Testing

The main task of this project is to successfully develop an algorithm that will be

energy-efficient. This section is the most time-consuming as it involves the creation

of a new routing mechanism and implementation in a simulation software, NS-2. The

latter has a quite steep learning curve and should take some time to master.

Projected Completion date: March 2013, Week 1

8

Chapter 3. Project Management

3.2.4 Results & Discussion

This chapter will present the outcome of the algorithm implementation which will

be compared to the initial objectives set. A critical appraisal will also be included as

well as a summary of the project.

Projected Completion date: March 2013, Week 4

3.2.5 Final Report

This will be the main project thesis. The final report should be clear and precise.

This report will represent the progression of the work throughout the different stages

of the project.

Submission Date : 26 April 2013

3.3 Work Breakdown Structure

The Work Breakdown Structure is used to decompose the project into smaller tasks.

The pre-defined milestones will be used as reference for the main deliverables and

help organise the total work scope. The WBS will provide a framework and guidance

to estimate the amount of time and effort to invest for each task.

The Work Breakdown Structure will consist of the WBS Chart diagram and a WBS

Dictionary.

3.3.1 WBS Chart

The following WBS chart portrays the different deliverables and the associated sub-tasks at different levels which are required to develop the project(Figure 3.1).

9

Chapter 3. Project Management

Energy Eficient Routing

Algorithm for MANETs

Project

Planning

Research

Algorithm Development

& Testing

Analysis

Project

Report

Aims &

Objectives

WBS

Project Schedule

Literature

Reading

Organise &

Summarise

Literature

Draft

Literature

Review

Develop Routing

Mechanism

Implementation

Data Colection

Analyse

Performance of

Algorithm

Discus Results

Draw Conclusions

Submit Draft

Await

Fedback

Revise Draft

Submit Final

Report

Figure 3.1: Work Breakdown Structure

10

Chapter 3. Project Management

3.3.2 WBS Dictionary

The WBS Dictionary ( Table 3.1) provides additional information on the deliverables

and sub-deliverables stated in the previous section. It lists the estimated duration

and dependencies of each task.

# Description Duration Dependency

1.0 Project Plan 4 Weeks

1.1 Finalise Aims & Objectives and determine Scope

of project

1 week

1.2 Devise WBS and Resource allocation 2 weeks 1.1

1.3 Prepare detailed project schedule on gantt chart

for two semesters

1 week 1.2

2.0 Research 9 weeks

2.1 Find additional relevant research work on

MANETS and literature reading

6 weeks

2.2 Organise and Summarise literature 5 weeks

2.3 Draft literature review 3 weeks 2.2

3.0 Algorithm Development & Testing 9 weeks

3.1 Develop new energy-efficient routing algorithm 7 weeks

3.2 Implementation & data collection 2 weeks 3.1

4.0 Results & Discussion 4 weeks

4.1 Analyze performance of routing algorithm 2 weeks

4.2 Discuss results and draw conclusions 2 weeks 4.1

5.0 Project Report 5 weeks

5.1 Submit first draft and wait for feedback from su-pervisor

3 weeks

5.2 Revise and amend draft if necessary 2 weeks 5.1

5.3 Submit Final Report 5.2

Table 3.1: WBS Dictionary

11

Chapter 3. Project Management

3.4 Project Schedule

The project schedule is designed using the Work Breakdown Structure and all the

dependencies among the tasks. It provides an accurate information on the start and

end time of the different stages. The schedule is represented on a gantt chart.

See Gantt Chart on Page 13.

12

Chapter 3. Project Management

Sept Oct Nov Dec Jan Feb Mar Apr

Project Planning

Finalise Aims & Objectives

Devise WBS

Prepare Project Schedule

Research

Literature Reading

Organise & Summarise literature

Draft Literature Review

Algorithm Development & Testing

Develop Routing Algorithm

Implementation & Data Collection

Results & Discussion

Analyse performance of Algorithm

Discuss Results & Draw Conclusions

Project Report

Submit draft & await feedback

Revise draft

Submit Final Report

Figure 3.2: Project Schedule 13

Chapter 4

Literature Review

4.1 Mobile Ad Hoc Networks

A Mobile Ad Hoc Network is defined as an autonomous collection of mobile

devices that are characterised by their self-configuring and self-administering abilities.

Most of the time, these mobile platforms (nodes) consist of wireless transmitters

and receivers which establish communication through intermediate nodes acting as

routers (Hoebeke et al., 2004, Macker and Corson, 1999). The nodes can generate

traffic to another node or even a group of nodes (Kuosmanen, 2003). The three main

types of traffic are defined by Sun (2001) as peer-to-peer, remote-to-remote and

dynamic. Communication between the nodes is done in a random, multi-hop and ad

hoc fashion which contrasts the static router topology and centralised administration

of the Internet and conventional mobile networks (Macker and Corson, 1999, Cano

and Manzoni, 2000). However, the dynamic nature of mobile ad hoc networks is the

main cause of frequent communication link failures (Kumar and Mishra, 2012).

4.1.1 History

Ad hoc networking is not a recent technology. Originating from the Defense Ad-vanced Research Projects Agency (DARPA), this concept dates back to the 1970’s.

The initial research aimed at utilizing radio networks to allow packet switched data

transmission (Bakht, 2005). The evolution to Mobile Ad Hoc Networks to its actual

status has gone through three generations:

4.1.1.1 1st Generation

In 1973, Kahn (1975), of the DARPA, developed the Packet Radio Network (PRNET)

in order to develop an experimental communication network with computer resources

14

Chapter 4. Literature Review

using Radio Communications. PRNET was mainly created to enable networking for

military purposes. The concept was based on a combination of existing communi-cation technologies, the ALOHA (Areal Location of Hazardous Atmospheres) and

CSMA (Carrier Sense Multiple Access). The PRNET is considered to be the first ad

hoc networking technology.

4.1.1.2 2nd Generation

The 1980’s saw the emergence of the 2nd generation ad hoc networks with the Sur-vivable Adaptive Radio Network (SURAN). It was a direct evolution from PRNET

and improved the latter in terms of radio performance and electronic attacks. Second

Generation systems also included the Global Mobile Information Systems (GloMo)

and Near Term Digital Radio (NTDR) Systems. Both of these made use of self-organisation and self-healing capabilities.

4.1.1.3 3rd Generation

Third Generation networks were mostly encouraged by the advent of newer mobile

devices such as PDAs , laptops, etc which brought a commercial aspect to ad hoc

networks. At the same time, a working group on MANETs was formed by the Internet

Engineering Task Force (IETF). The IETF working group aims at standardising the

routing protocols and provide a framework for developping future applications using

ad-hoc technology. The major standards that proved beneficial to ad hoc networks

were Bluetooth, HIPERLAN and IEEE 802.11.

4.1.2 Characteristics

Originally designed for military purposes, MANETs had a set of characteristics that

were particularly adapted to those types of networks. The third generation of ad hoc

networking are more targeted at commercial and industry-related ends. As a result,

some of these properties now present some challenges for operation and maintenance.

The main features that characterise MANETs are (Macker and Corson, 1999, Sun,

2001):

15

Chapter 4. Literature Review

• Dynamic Topology - The mobile platforms can move freely and arbitrar-ily, resulting in a completely random and unpredictable connectivity between

the nodes that form the ad hoc network. Deprived of a fixed infrastructure,

MANETs have to be able to constantly adapt themselves for efficient communi-cation. The changing topology of mobile ad hoc networks is the cause of certain

issues in routing and addressing and can even lead to network partitioning.

• Autonomous - The nodes are considered independent. In other words, in a

multi-hop ad hoc network, there is no requirement for an intermediate routing

device. The nodes, in addition to their basic processing capabilities, can also

perform routing and switching tasks.

• Distributed Architecture - The lack of a centralised administration implies

that the control and network management operations need to be allocated to

the endpoints. These terminals constantly work together to make sure functions

such as security and routing are implemented effectively.

• Varying Link Capacity - As the communications occur over wireless links in

MANETs, they are more prone to achieve a lower and varying link capacity than

wired connections. The wireless channels present higher BER and interference

as well as a lesser bandwidth. It is quite common for mobile ad hoc networks

to reach or even go beyond the optimal network capacity.

• Energy Constrained - The devices in a mobile ad hoc network rely mostly

on limited power sources such as batteries. The amount of energy spent by

the nodes is a crucial factor to consider while designing networks and resulting

protocols in order to achieve maximum efficiency and network lifetime.

• Limited Physical Security - Mobile ad hoc networks are not only concerned

with the security issues known to wireless networks. More vulnerabilities are

present due to the distributed archicture and operation. Different methods of

authentication and key management are required.

16

Chapter 4. Literature Review

4.1.3 Applications

As the number of wireless devices keeps increasing, mostly due to the major advances

in wireless communications, mobile ad hoc networking has gained a considerable

importance. MANETs allow devices to be added or removed from the network more

easily than conventional networks.

The range of applications for MANETs is very extensive and adapts to both large

and small highly dynamic networks with energy constraints (Sun, 2001). Table 4.1

lists the present and future possible applications of MANETs in their corresponding

fields.

Application Possible Scenarios/services

Tactical Networks Military Communications & Operations

Automated Battlefields

Emergency Services Search and Rescue Operations

Disaster Recovery

Replacement of fixed infrastructure in case of Envi-ronmental Disasters

Commercial & Civilian

environments

E-commerce: electronic payments anytime and any-where

Business: dynamic database access, mobile offices

Vehicular Services: road or accident guidance, tran-mission of road and weather conditions, inter-vehicle

networks

Home & Enterprise Net-working

Home/Office Wireless Networking

Personal Area Networks (PAN)

Networks at construction sites

Education Universities & Campus Settings

Virtual Classrooms

17

Chapter 4. Literature Review

Ad Hoc Communications during meetings or lectures

Entertainment Multi-User Games

Wireless P2P Networking

Robotic Pets

Theme Parks

Sensor Networks Home Applications: smart sensors and actuators em-bedded in consumer electronics

Body Area Networks (BAN)

Data Tracking of environmental conditions, animal

movements, chemical/biological detection

Context Aware Services Follow-on Services: call forwarding, mobile

workspace

Information Services: location specific services, time

dependent services

Infotainment: Touristic Information

Coverage Extension Extending Cellular Networks

Linking up with the Internet, intranets, etc.

Table 4.1: Applications of Mobile Ad Hoc Networks. Source: Hoebeke et al. (2004)

4.2 Routing in MANETs

Bertsekas (1993) refers to routing as the network layer process by which packets

are guided from a source node to its corresponding destination throughout a net-work . The ways by which the routing devices establish communication or share

information on routes between two nodes are specified by routing protocols. These

routing protocols are based on a complex set of algorithms that establish the most

appropriate route selection according to specific conditions in the most efficient way

possible. The efficiency of the algorithms is often measured in terms of throughput,

delay or number of hops.

18

Chapter 4. Literature Review

In mobile ad hoc networks however, the traditional routing protocols cannot be ap-plied efficiently. This is mainly due to the mobility of the nodes and the fact that the

nodes themselves perform the routing and switching functions. This section reviews

the main developments as far as routing in MANETs is concerned and provides an

overview of the different protocols that have been developed to suit ad hoc network-ing.

4.2.1 Classification of Ad Hoc Routing Protocols

Due to the large variety of different routing protocols that have been proposed for

MANETs, it was essential to have an appropriate taxonomic classification for these

protocols. Initially, they were categorized into either table-driven or source-initiated

on-demand protocols.

• Table-Driven protocols involves keeping updated routing tables at each node.

To achieve network consistency due to the changes in topology, the nodes share

constant route updates of the network.

• Source-Driven On-Demand protocols, on the other hand, work in a more reac-tive fashion. They involve initiating a route discovery procedure only when the

routes are required. Topology changes are addressed to by a route maintenance

process which discards invalid routes and updates with new ones.

However, this categorization has some drawbacks because it does not allow to fully

distinguish the different protocols with enough accuracy. In his paper, Kuosmanen

(2003) discussed another model to classify the routing protocols in mobile ad hoc net-works. This particular model differentiates the protocols with respect to some basic

design and operational criteria: Communication Model, Structure, State Information

& Scheduling.

The communication model may be either single-channel or multi-channel. Single-channel, which consists of using a sharedmedia, usually have a CSMA/CA orientation

while multi-channel protocols use a combination of channel allocation and routing.

These are mostly utilised on CDMA or TDMA-based communication networks.

19

Chapter 4. Literature Review

Single

Channel

Uniform Topology

based

Proactive

Reactive

Destination

based

Proactive

Reactive

Non-Uniform

Neighbor

Selection

Partitioning

Multi

Channel

Uniform

Non-Uniform

Unicast Ad Hoc Routing Protocols

Figure 4.1: Classification of Ad Hoc Routing Protocols

Protocols can also be defined according to the hierarchy of the nodes. The structure

defines how the nodes are selected and treated. Uniform protocols assume no distinc-tion among the nodes and the terminals transmit and respond to control messages

similarly. Non-Uniform protocols differentiate the nodes by the way they deal with

routing control information.

The state information based protocols decides whether large scale topology and routes

information are maintained at each node or if the nodes keeps informed of a certain

group of nodes only. The methods to make this distinction can be destination or

topology-based.

Scheduling is another important factor in determining whether the routing informa-tion is constantly updated at each terminal or does it occur only when route discovery

process is triggered. The protocols can be classified as proactive or reactive.

20

Chapter 4. Literature Review

The taxonomy for classifying the ad hoc routing protocols as depicted by the model

described by (Kuosmanen, 2003) are represented in Figure 4.1. However, it should

be noted that this model deals with Unicast protocols only. Unicast operation is

the most common in MANETs and involve communication from a Source to a single

Destination node (Kumar et al., 2010).

Shrivastava et al. (2005) also classifies the ad hoc routing protocols, but adopts a

different strategy to that of (Kuosmanen, 2003). The former does not account for

the type communication channel and mentions a more recent category, which is a

combination of Proactive and Reactive Protocols, known as Hybrid Protocols. The

hybrid protocols are reactive on a global scale and more proactive locally.

However, classification of ad hoc routing protocols is very subjective to the context

and specific application of the mobile ad hoc network. For example, Guo et al. (2007)

categorizes the protocols according to the kinds of data transfer applied for WSN in a

Coal Mine Data Acquisition. These are query-based, cluster-based, geographic based

and dependability.

To properly assess the different routing protocols in order to determine their energy

conservation ability and efficiency, the following sections review the most common

protocols by grouping them into Proactive, Reactive and Hybrid:

Category Protocols

Proactive Destination Sequenced Distance Vector Routing (DSDV)

Hierarchical State Routing (HSR)

Global State Routing (GSR)

Reactive Dynamic Source Routing (DSR)

Ah Hoc On-demand Distance Vector Routing (AODV)

Location Aided Routing (LAR)

Hybrid Zone Based Routing Protocol (ZRP)

Table 4.2: Common Ad Hoc Routing Protocols

21

Chapter 4. Literature Review

4.2.2 Pro-active Protocols

4.2.2.1 DSDV

The Destination-Sequenced Distance-Vector protocol, proposed by Perkins and Bhag-wat (1994), was an improved version of the Distance-Vector algorithm. Basically dis-tance vector algorithms involves that each node i keeps the distances {d

x

ij

} for every

other destination x, where j is the range of the neighbouring nodes of i. The next

hop k is determined by finding the shortest distance among the range stored (Figure

4.2). The minimum route is the result of a succession of hops to the destination node.

This algorithm corresponds to the Distributed Bellman-Ford algorithm (DBF).

Node i

Node j

Node k

Destination

x

If {dik(x)} = min{dij(x)}

Updated

information

{dij(x)}

Node j

Node k

Figure 4.2: Destination Sequenced Distance Vector Routing

DSDV was designed to account for the two major drawbacks of the DBF: formation

of loops and inflexibility with respect to mobile nodes. The DSDV is a table-driven

protocol, meaning each nodes maintain a complete routing table containing destina-tions and number of hops to these destination numbers as well as a sequence number.

The Sequence Number is used to determine topology changes and is created by the

destination node. A different Sequence Number from the one in store indicates a

more recent route information.

A simple example, illustrated in Figure 4.3 and Table 4.3, presents how the routing

information are stored at each terminal. The network is composed of 6 mobile nodes

and the routing table at the node, N5 is considered.

22

Chapter 4. Literature Review

N1

N2

N3

N4

N6

N5

Figure 4.3: Example of DSDV

Destination Next Hop Metric Seq_No

N1 N3 3 N1_22

N2 N3 2 N2_14

N3 N3 1 N3_32

N4 N3 3 N4_40

N5 N5 0 N5_26

N6 N6 1 N6_18

Table 4.3: Routing Table in DSDV

To maintain network consistency, the DSDV protocol implies periodic updates of

each node’s next-hop tables. The advertisement of these updates is carried out either

through broadcasts or multi-casts and are communicated in two possible ways: full

dumping or incremental updates. Full dumping involve updating the whole table

whereas the incremental method will update the modified routes only. The rate

of updating these tables largely depend on the mobility of the nodes (Kumar and

Mishra, 2012).

4.2.2.2 HSR

Hierarchical State Routing uses the concept of clustering and partitioning techniques

to improve the performance of the network. This scheme was first proposed by Iwata

et al. (1999) in order to overcome the issue of mobility and location management in

ad hoc routing. HSR utilizes a combination of multi-level hierarchies and efficient

location management.

23

Chapter 4. Literature Review

The nodes are grouped into both physical clusters and logical partitions. The fun-damental principle of HSR is to recurrently elect cluster heads at a lower level and

these form part of the next higher level. The elected heads will only keep information

about its own cluster and communicate them to neighbouring cluster heads through

special nodes known as gateways.

Figure 4.4 gives an illustration of how the HSR scheme actually works. Through dif-ferent existing cluster forming mechanisms, physical clusters (C −0, C −1, C −2, C −3)

are created at level 0 and these may contain three types of nodes: cluster heads

(1, 2, 3, 4), internal nodes (5, 9, 10) and gateways (6, 8, 10). The nodes will monitor

and broadcast the link state of their neighbours and the broadcasted information is

summarized by the cluster head-nodes, which in turn communicate them to neigh-bouring cluster heads.

Level 1 cluster (C 1 − 1) is generated consisting of heads 1 & 2. For these 2 nodes to

communicate, a virtual link that physically exist through gateway node 6, is created.

Similarly other cluster virtual links are defined between the cluster heads. This

process is done recursively to elect cluster-head nodes to establish Level 2.

Figure 4.4: Clustering in Hierarchical State Routing. Source: Iwata et al. (1999)

24

Chapter 4. Literature Review

4.2.3 Reactive Protocols

4.2.3.1 AODV

Ad-Hoc On-Demand Distance-Vector Routing is a reactive protocol that is directly

adapted from the DSDV protocol. As depicted in Section 4.2.2.1, DSDV keeps a list

of all the routes from a source node to every other destination in an ad-hoc network.

In contrast to (Perkins and Bhagwat, 1994), AODV was developed by Perkins and

Royer (1997) to optimize this feature by limiting the amount of route information

stored. The AODV protocol maintains information about the routes that participate

in the active links only.

AODV functions using two main procedures: Route Discovery and Route Mainte-nance. Route Discovery is triggered only when a source node needs to establish

communication with another node that is not in his routing table. This is carried

out using request and reply packets, RREQ and RREP respectively.

The RREQ is broadcasted in the network during path discovery and contains certain

parameters that will be used for checking existence of route to destination and validity

of that link.These parameters are defined in Table 4.4.

Source Ad-dress

Request ID Source

SEQ_#

Destination

Address

Destination

SEQ_#

Hop

Count

Table 4.4: AODV RREQ Parameters

When a valid route is detected, A RREP is unicasted back to the source node while

storing information such as source address and hop count. The complete structure

of the RREP packet is presented in Table 4.5.

Source Ad-dress

Destination

Address

Destination

SEQ_#

Hop Count Life Time

Table 4.5: AODV RREP Parameters

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Chapter 4. Literature Review

Route Discovery is initiated by RREQ broadcasts to neighbouring nodes. Until

a valid RREP is obtained, the nodes keeps updated Reverse Route entries of the

initiator and keeps forwarding the RREQ. Once the route has been found, and the

source node receives the RREP, a Forward Path is set up to the destination and the

link becomes active. Figure 4.5 below illustrates the Route Discovery in AODV.

S

D

Propagation of RREQ

Reverse Route Entry

Path of RREP

Figure 4.5: AODV Route Discovery

To achieve network consistency, neighbouring links are constantly monitored for fail-ures. This is achieved by using Hello messages. In case of invalid link detection, the

corresponding node informs the other nodes by broadcasting error messages RERR

(Figure 4.6). When the source node acknowledges the RERR , it may initiate a new

Route Discovery procedure.

S

D

RERR

RREQ

Active Link

Figure 4.6: AODV Route Maintenance

4.2.3.2 DSR

The Dynamic Source Routing protocol (Johnson et al., 2001)

26

Chapter 4. Literature Review

Figure 4.7: DSR Route Discovery and Maintenance. Source: Johnson et al. (2001)

4.2.3.3 LAR

4.2.4 Hybrid Protocols

4.2.4.1 ZRP

4.3 Energy Efficient Routing in MANETs

4.3.1 Power Aware Metrics

4.3.2 Energy-efficient Routing Protocols

4.3.2.1 Transmission Power Control

4.3.2.2 Load Distribution

4.3.2.3 Sleep & Power-down

4.4 Summary

27

Chapter 5

Project Progress

28

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