Efficient Route Discovery in Mobile Adhoc Network 1271225228 Phpapp01

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Project ReportProject ReportProject ReportProject Report

ononononEfficient Route Discovery inEfficient Route Discovery inEfficient Route Discovery inEfficient Route Discovery in

MobileMobileMobileMobileAd HocAd HocAd HocAd HocNetworkNetworkNetworkNetwork

DEVELOPED BYDEVELOPED BYDEVELOPED BYDEVELOPED BY

Ankur Ghosh

Ankur Paul

Pradip Kumar Mahato

Somarka Chakravarti

Soumyojit Chakraborty

PROJECT GUIDEPROJECT GUIDEPROJECT GUIDEPROJECT GUIDE

Mr. Biplab Mondal

Lecturer, Dept. of Computer Science & Engineering

December, 2009

Asansol Engineering College

Kanyapur, Asansol, Burdwan -713304


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ACKNOWLEDGEMENTACKNOWLEDGEMENTACKNOWLEDGEMENTACKNOWLEDGEMENT

It is a matter of great pleasure for us to acknowledge our feelings of

extreme gratitude and sincere regards to Mr. Biplab MondalMr. Biplab MondalMr. Biplab MondalMr. Biplab Mondal, Lecturer, Department

of Computer Science & Engineering, Asansol Engineering College, for the regular

& dedicated guidance provided by him. It was because of his steady guidance that

we could bring this project to its present form.

We also take this opportunity to thank Mr. Sw. Sw. Sw. Swapan Bhattacharyaapan Bhattacharyaapan Bhattacharyaapan Bhattacharya,,,, Head

of the Department, Department of Computer Science & Engineering, Asansol Engineering College, who was always there to provide us with all sort of support,

be it technical or moral.

We would also like to acknowledge the help and support of Mr. AmarMr. AmarMr. AmarMr. Amar Kr.Kr.Kr.Kr.

GangulyGangulyGangulyGanguly,,,, Principal, Asansol Engineering College.

The acknowledgment will remain incomplete if we do not specially give

thanks to our Project Laboratory in-charge, Mr. SumanMr. SumanMr. SumanMr. Suman MallickMallickMallickMallick for providing us

the optimum facilities in the laboratory which was of immense help in developing

the project.

Project TeamProject TeamProject TeamProject Team

Ankur Ghosh

Ankur PaulPradip Kumar Mahato

Somarka Chakravarti

Soumyojit Chakraborty


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CERTIFICATECERTIFICATECERTIFICATECERTIFICATE

This is to certify that the following project entitled

Efficient Route Discovery in MobileAd Hoc Network

submitted by

Ankur Ghosh

Ankur PaulPradip Kumar Mahato

Somarka ChakravartiSoumyojit Chakraborty

has been carried out in the Department of Computer Science & Engineering at AsansolEngineering College under West Bengal University Of Technology for the degree of B-TECH.

It is a complete fulfilment of their 7th semester project.

So, the performance of the group deserves my approval and acknowledgement.

Approved by

........................................Project Guide

Biplab Mondal

Lecturer, Dept. of CSE,

Asansol Engineering College

Recommendation :

Recommended/Not Recommended

.................................................. ................................................Internal Examiner External Examiner


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CREDITSCREDITSCREDITSCREDITS

Project Guide

Mr. Biplab MondalLecturer, Department of Computer Science & Engineering, Asansol Engineering College

Project Team

1. Ankur Ghosh

Roll No. : 10801061076

Registration No : 108010111062

Stream : Computer Science & Engineering

Batch : 2006 - 2010 ( 4th

year )

2. Ankur Paul

Roll No. : 10801061035



Batch : 2006 - 2010 ( 4th

year )

3. Pradip Kumar Mahato

Roll No. : 10801061071

Registration No : 108010141006Stream : Computer Science & Engineering

Batch : 2006 - 2010 ( 4th

year )

4. Somarka Chakravarti

Roll No. : 10801061065



Batch : 2006 - 2010 ( 4

th

year )

5. Soumyojit Chakraborty

Roll No. : 10801061044



Batch : 2006 - 2010 ( 4th

year )


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INDEXINDEXINDEXINDEX

PPPPARTICULARSARTICULARSARTICULARSARTICULARS PPPPAGEAGEAGEAGE NNNNOOOO.

1. Introduction 11.1 Introduction to MobileAd Hoc Network 1

1.2 Background & Motivation 2

2. FResher Encounter SearcH 32.1 FRESH Idea 3

2.2 FRESH Algorithm 5

3. Implementation 73.1 Data Flow Diagram 7

3.2 Output 10

3.3 System Requirements 13

4. Performance Analysis 144.1 Performance Criterion 144.2 Simulation Environment 15

4.3 Age Gradients 17

5. Conclusion & Future Scope 186. References 19


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TTTTABLE OFABLE OFABLE OFABLE OFIIIILLUSTRATIONSLLUSTRATIONSLLUSTRATIONSLLUSTRATIONS

PPPPARTICULARSARTICULARSARTICULARSARTICULARS PPPPAGEAGEAGEAGE NNNNOOOO....

Figure 2.1 : An example FRESH route for N = 32000nodes, with a random walk mobility process. 4

Figure 3.1 : Level 0 DFD 7

Figure 3.2 : Level 1 DFD 7

Figure 3.3 : Level 2 DFD (I) 8

Figure 3.4 : Level 2 DFD (II) 9

Screenshot 3.1 : Initial Look 10

Screenshot 3.2 : Initial Random Network with source & destination selected 10

Screenshot 3.3 : Network after random motion for 1 minute 11

Screenshot 3.4 : Route given by FRESH 11

Screenshot 3.5 : Selecting destination without selecting source 12

Screenshot 3.6 : Selecting a source as a destination 12

Screenshot 4.1 : Route after warm-up for 10 seconds 16

Screenshot 4.2 : Route after warm-up for 15 minutes 16

Figure 4.1 : Age gradient, random walk. (Empirical conditional

mean of distance, conditional on the encounter age). 17


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1.1.1.1. INTRODUCTIONINTRODUCTIONINTRODUCTIONINTRODUCTION1.11.11.11.1 IIIINTRODUCTION TONTRODUCTION TONTRODUCTION TONTRODUCTION TOMMMMOBILEOBILEOBILEOBILEAAAADDDDHHHHOCOCOCOCNNNNETWORKETWORKETWORKETWORK

A "MobileAd Hoc Network" (MANET) is an autonomous system of mobile

routers (and associated nodes) connected by wireless links, the union of whichforms an arbitrary graph.

Wireless mobile hosts of Mobile Ad Hoc Network communicate with eachother, in the absence of a fixed infrastructure. The routers are free to move

randomly and organize themselves arbitrarily. Thus, the networks wirelesstopology may change rapidly and unpredictably. Routes between two hosts in aMobileAd Hoc Network (MANET) may consist of hops through other hosts in thenetwork. Therefore, the task of finding and maintaining routes in MANET is

nontrivial. Such a network may operate in a standalone fashion, or may beconnected to the larger Internet.

Routing protocols for MobileAd Hoc Networks generate a large amount of

control traffic when node mobility causes link states and the network topology tochange frequently. On the other hand, resources such as bandwidth and battery

power are usually severely constrained in such networks. Therefore, minimizingthe control traffic to set up and maintain routing state is one of the main challenges

in the design of scalable routing protocols for MobileAd Hoc Networks.

Mobility can be of two types. In the waypoint mobility model, each node

chooses a random target which is uniformly distributed in the surface and advancestowards it at a constant velocity. When it reaches the target, a new target is

generated and the node moves again. In the random walk model, nodes move ateach step in one of the four cardinal directions, and reflect at the boundary.

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1.21.21.21.2 BBBBACKGROUNDACKGROUNDACKGROUNDACKGROUND&&&&MMMMOTIVATIONOTIVATIONOTIVATIONOTIVATION

Large amount of control traffic is generated by the routing protocols

implemented for Mobile Ad Hoc Networks in which link states and the networktopology change frequently. Resources such as bandwidth and battery power areusually severely constrained in such networks. Therefore, minimizing the control

traffic to set up and maintain routing state is one of the main challenges in the

design of scalable routing protocols for MobileAd Hoc Networks. One approach to

limit control traffic is to establish routes on demand rather than proactively. On-demand routing protocols only establish a route to a destination when it is

necessary to send packets to that destination, and therefore incur less overhead atthe expense of higher route setup latency. Hybrid routing protocols combine both

on-demand and proactive elements for more flexibility in the latency-overhead

tradeoff.

On-demand routing overhead can be broken down into two components :route discovery and route maintenance. Their relative costs vary depending on the

protocol and scenario, but in general route discovery tends to be costly. In thisproject, we propose a new approach to reduce the cost of route discovery, which

can benefit both pure on-demand and hybrid routing protocols.

When a source node first wishes to establish a route to a destination, it must

search the network until it finds either the destination or another node which has a

route to the destination. Many of the proposed protocols for Ad Hoc Networksperform a flood based route discovery, whereby a Route REQuest (RREQ) packetis flooded across the network, possibly using an expanding ring search to "grow"

the flood until the destination is found. This search is omnidirectional as the sourcenode does not know where the destination lies the flood cannot favour any one

particular direction.

In this project, we propose an algorithm called FRESH that improves the

performance of route discovery over omnidirectional approaches. FRESH achievesthis performance improvement by exploiting the history of last encounters between

nodes (two nodes encounter each other when they are directly connectedneighbours). Our work is motivated by a simple observation the history of last

encounters between nodes contains valuable, but noisy information about the

current network topology.

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\

Figure 2.1 : An example FRESH route for N = 32000 nodes, with a random walk mobility process.

What enables FResher Encounter SearcH to compute good routes at a lower

cost is a single-step route discovery. The basic principle is simple: For mostmobility processes, the distance travelled during a time interval of duration t is

positively correlated with t. We refer to this as time-distance correlation.

Now consider three nodes i, j, and d. At the present time t = 0, node i is

separated from node d by a distance Di, similarly node j is separated from noded by a distance Dj. The intuition behind FRESH is that if TLE (i,d) < TLE(j,d),

then with high probability Di < Dj. Simply put, a node that was my neighbour 5

minutes ago is probably closer to me than a node that was my neighbour 5 hoursago. If time-distance correlation holds then successive FResh Encounter SearcHes

will advance towards the destination. This will result in a directional route

discovery. In common mobility processes time-distance correlation holds well

enough for the algorithm to work very effectively.

Though successive iterations of the FResher Encounter SearcH on average

bring us closer to the destination, they may not always advance along a straightline, and so we may not obtain the shortest-path route. Since FRESH establishes

routes at lower cost than single-step methods, one may consider that we trade off

some route quality for a reduction in search cost and so we must be sure that routes

remain good enough so that this is worthwhile.[4]


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2.22.22.22.2 FRESHFRESHFRESHFRESHAAAALGORITHMLGORITHMLGORITHMLGORITHM

Before we actually go into the FRESH algorithm, we would like to put

forward to important properties based on which the protagonized algorithm issupposed to work.

PROPERTY 1: The search primitive is omnidirectional, that is to say it does notfavour any specific direction for finding the required node.

PROPERTY 2:The search proceeds in concentric rings of expanding radius until a

node is found which satisfies a given condition.

FRESH Algorithm :

In this algorithm the nodes keep a table of their most recent encounters times

with all the other nodes they have encountered. This table is called the TLEtable.

The pseudo-code given ahead invokes the search primitive through an

abstract interface which allows a querying node N to find the nearest anchor nodeA having seen the destination node D more recently than a time T. This search is

invoked by calling nextAnchor(D,T), which triggers a network search and returnsA. The search process creates routing state in the network which will allow N to

subsequently send packets to A. This state will be used by the notifyNextAnchorcall to instruct A to pursue the route discovery. More precisely,

notifyNextAnchor(A,D) will send a packet to A, which triggers invocation of thecall FRESH(D) on node A. We note that the packet sent by the

notifyNextAnchor(A, D) call does not need to carry the time T representing the

current node's encounter age with D since node A only needs its own encounterage with D in order to iterate the search.

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The algorithm, which is run at every node in the network, is as follows:

procedure FRESH (D)begin

if(thisnode.ID = D) thenreplyToSource()

elsebegin

T := prevEncounterAge(D);A := findNextAnchor (D, T);if (A != D) then

notifyNextAnchor(A, D);end

end

replyToSource() is a invoked when the route is found, i.e., the last node encountered in the search

is the destination itself, and notifies the source.prevEncounterAge(D) returns the time since the last encounter of the particular node with thedestination.

procedure findNextAnchor(D, T)begin

repeatcurrentDist:=0;repeat

currentDist:=currentDist + unitDist;presentNode:=ID of the node at currentDist;

if(T>prevEncounterAge(D) of presentNode;return presentNode;

for all nodes at currentDistforever

end

currentDist : Distance at which Anchor nodes are checked

unitDist : Lowest distance for incrementing search area for anchor nodes

presentNode : Node under concern to be checked for next Anchor Node

notifyNextAnchor(A, D) transfers control to the Anchor Node A & executes the procedure

FRESH(D) at A.

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3.3.3.3. IMPLEMENTATIONIMPLEMENTATIONIMPLEMENTATIONIMPLEMENTATION3333.1.1.1.1 DDDDATAATAATAATAFFFFLOWLOWLOWLOW DDDDIAGRAMIAGRAMIAGRAMIAGRAM

Figure 3.1 : Level 0 DFD

Figure 3.2 : Level 1 DFD

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Simulation

Environment

& Route

Discovery0

Simulation

Environment

0.1

Route

Discovery

0.2

No. of Nodes,

Source id,

Destination id

Efficient Route

No. of Nodes,

Source id,

Destination id

Efficient Route

Source id,

Destination id


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Drawing the

Background

0.1.1

Generate

Random

Locations

0.1.2

Draw the

Nodes

0.1.3

Generating

New

Locations

0.1.4

Node Records

No. of Nodes,

Source id,

Destination id

Source id,

Destination id

Node Locations

Node Location

Nodes new Location

Start/Stop Motion

[8]

Figure 3.3 : Level 2 DFD (I)


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DDDDATAATAATAATA DDDDICTIONARYICTIONARYICTIONARYICTIONARY

No. of Nodes :integer

Source id : Node id

Destination id : Node id

Start/Stop Motion : User Command

Node Location : {integer} 2

Nodes New Location : {integer} 2

Next Anchor : Node id

Efficient Route : Source id + { Node id }*+ Destination id

[9]

FRESH

0.2.1

nextAnchor

0.2.2

Current Anchor id,

Destination idSource id,

Destination id

Efficient Route

Next Anchor id

Figure 3.4 : Level 2 DFD (II)


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3.23.23.23.2 OOOOUTPUTUTPUTUTPUTUTPUT

1. An Initial Screenshot of the system asking the user for the no. of nodes in the network.

Screenshot 3.1 : Initial Look

2. The initial random network. The user can select a source by clicking on Select Source & then clicking on the

desired node. Destination can be selected or deselected in a similar manner. The following screenshot shows

the initial network with source & destination selected.

Screenshot 3.2 : Initial Random Network with source & destination selected

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3. The user can start/stop random motion of the nodes by using the Start/Stop Random Motion button. The

following screenshot shows the same network after random motion for 1 minute.

Screenshot 3.3 : Network after random motion for 1 minute

4.The FRESH algorithm is invoked on pressing the Show/Hide route button. The route discovered is shown in

the following screenshot.

Screenshot 3.4 : Route given by FRESH

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HANDLING ERRORSHANDLING ERRORSHANDLING ERRORSHANDLING ERRORS

1.The following message box is displayed if the user tries to select a destination before selecting the source.

Screenshot 3.5 : Selecting destination without selecting source

2.The following message box is displayed if the user tries to select the source node as a destination.

Screenshot 3.6 : Selecting a source as a destination

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3.33.33.33.3 SSSSYSTEMYSTEMYSTEMYSTEMRRRREQUIREQUIREQUIREQUIREMENTSEMENTSEMENTSEMENTS

Hardware Requirements

A PC (or Laptop) with mouse

65MB RAM

256 MB of Hard Disk Space

Software Requirements

Operating System : Windows (XP, NT, Vista) or Linux (Red Hat, ubuntu, etc)

Development tool : jdk1.2.4 (or later)

N.B : The system can support a maximum input of 3500 nodes. An input of more than 3500

nodes can result in unexpected results.

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4.4.4.4. PERFORMANCEPERFORMANCEPERFORMANCEPERFORMANCE ANALYSISANALYSISANALYSISANALYSIS4444.1.1.1.1 PPPPERFORMANCEERFORMANCEERFORMANCEERFORMANCECCCCRITERIONRITERIONRITERIONRITERION

The first performance criterion will be the cost of the n searches (n is the no.

of anchors) in a route discovery. The baseline to which we will compare FRESH

search cost is the search cost of a single-step route discovery as employed byexisting protocols. Our simulation shows that FRESH allows for a substantial

reduction in this cost.

The second performance criterion is the quality of routes. Though successive

iterations of the FResher Encounter SearcH on average bring us closer to the

destination, they may not always advance along a straight line, and so we may notobtain the shortest-path route. Since FRESH establishes routes at lower cost than

single-step methods, one may consider that we trade off some route quality for areduction in search cost and so we must be sure that routes remain good enough so

that this is worthwhile. We have performed simulations to verify the scaling

performance of FRESH at large network sizes with a random walk.

The simulations used two metrics to evaluate the performance of the

protocol: search cost and route quality. In this section we report the results and

further discuss two other important aspects of routing performance: proactiveoverhead and latency.

The search costof a route discovery is the overhead necessary to build the route from a source to a destination. In the case of the on-demand protocols we are

considering here, this will be the cost of the search(es) associated with the routediscovery.

Route quality measures the difference between the route obtained by the

algorithm and the shortest-hop path.

Our purpose is to evaluate the performance of FRESH in relation only to the

mobility process and the size of the network. Nodes are one-hop neighbours whenthey come within unit distance of each other, and interferences and collisions are

not modelled. We note that this simplification is neutral to the evaluation since wehave no cross-traffic.

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4.24.24.24.2SSSSIMULATIONIMULATIONIMULATIONIMULATIONEEEENVIRONMENTNVIRONMENTNVIRONMENTNVIRONMENT

The topology is a continuous square surface. The mobility model employed

here is random walk in which nodes move at each step in one of the four cardinaldirections, and reflect at the boundary.

The simulations run in two phases: warm-up and route computation. In the

warm-up phase, nodes move according to the chosen mobility process, populatingtheir tables with the most recent encounter times of each peer node that they

encounter. Ideally the warm-up phase runs until an encounter ratio of 40% is

attained, where the encounter ratio is the proportion of node pairs that have

encountered at least once since the beginning of the warm-up.

Once the warm-up is complete, we apply FRESH to sequentially compute a

number of routes between randomly chosen source-destination pairs and record thestatistics of interest to us. We note that a single route discovery happens on a

timescale of tens or hundreds of milliseconds whereas node mobility occurs on atimescale of several seconds or minutes. This allows us to use the approximation

that nodes' positions are static for the duration of a route discovery.

Proactive Overheads: During and after the route computation FRESH

requires that nodes keep track of their one-hop neighbourhood in order tomaintain their encounter tables with up-to-date information. One solution is for

nodes to broadcast periodic hello messages in order to inform one-hopneighbours of their presence.

Latency: It is an important aspect of routing protocol performance. In this

paragraph we explain why latency of FRESH is similar to the latency of single-step methods. We consider two types of latency: route establishment latency and

round-trip time (RTT) latency. Route establishment latency is the time elapsedbetween the moment when a source requests a route to the destination and the

moment when it has a route and may start sending packets. However the main

source of latency in route establishment will be the time spent doing expandingring searches.

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Screenshot 4.1 : Route after warm-up for 10 seconds

Screenshot 4.2 : Route after warm-up for 15 minutes

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4.4.4.4.3333AAAAGEGEGEGEGGGGRADIENTSRADIENTSRADIENTSRADIENTS

In order to see how distance is related to encounter age, we have plotted the

empirical conditional mean of the distance between node pairs, conditional upontheir encounter age. The figure shows this empirical mean for the random walk,over a convenient node density. Each point in this graph was computed by

considering all the node pairs whose last encounter time is within a certain ageinterval, and averaging over the distance between these node pairs.

Figure 4.1 : Age gradient, random walk. (Empirical conditional mean of distance, conditional on the encounter age).

We observe that as the encounter age increases, the expected distanceconverges to a constant which is on the order of a half side of the square surface.Therefore, once a node moves toward its second target, its position is already

independent of its starting point.We see that once the stationary regime is reached,the empirical mean of the distance between two nodes is constant, and therefore

does not vary with the encounter age. After the first two hops we reach a node

whose encounter age lies within the descending area of the age gradient, and we

see that the route makes good progress from there onward.

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5555.... CONCLUSIONCONCLUSIONCONCLUSIONCONCLUSION &&&& FFFFUTUREUTUREUTUREUTURESSSSCOPECOPECOPECOPE

We have introduced an algorithm for efficient route discovery in MobileAd

Hoc Networks that uses iterated Fresher Encounter SearcHes. A novel aspect of

this algorithm is that it takes advantage of the fact that nodes are moving.Compared to geographic algorithms, an advantage of our proposal is that it does

not assume any hardware add-ons such as GPS receivers. In developing this projectwe have implemented the FRESH algorithm which counts over a variety of

flooding and routing techniques.

Though this project has focused on the application of routing between peer

nodes, we believe that FRESH will have other applications in Ad Hoc networks.For example, assuming anAd Hoc network which has one or more gateways to the

wired internet, FRESH could be used by a mobile node to establish a route to thenearest gateway.

Under a conservative search cost metric, where we assume a naive searchstrategy, our simulations indicate that the algorithm reduces the flood overhead by

an order of magnitude in large networks. This is significant since route discovery isa major source of overhead inAd Hoc routing protocols. We believe that this route

discovery algorithm may therefore be a useful component in designing routing protocols that scale to larger number of nodes. The search cost will be further

reduced with an enhanced search strategy which could for example exploit thedirectionality of sequential searches.

Future Scope : As part of future work, a full routing protocol incorporating theideas described in this project can be developed. One topic that will deserve further

attention is the possibility to trade off better routes in exchange for a higher searchcost, (alternatively to trade off a sub-optimal route for a lower search cost) by

recursively applying FRESH to interior portions of the route. This trade-offdeserves to be adjustable dynamically, since the optimal point will vary widely

depending on the duration of a connection.

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6666.... REFERENCESREFERENCESREFERENCESREFERENCES

1. Age Matters : Efficient Route Discovery in Mobile Ad Hoc Networks

By Henri Dubois Ferriere, Matthias Grossglauser, Martin Vetterli

School of Computer & Communication Sciences

EPFL

1015 Lausanne, Switzerland

2.

Data Communications & Networking

By Behrouz A. Forouzan

3. Computer Networks

By William Stallings

4.

Java : The Complete Reference

By Herbert Schildt

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Efficient Route Discovery in Mobile Adhoc Network 1271225228 Phpapp01

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