Packet Loss in Mobile Ad Hoc Networks

Abstract — We investigate packet loss in mobile ad hoc networks via simulation. Ad-hoc on-demand distance vector (AODV) and destination-sequenced distance vector (DSDV) are chosen as representatives of the on-demand and proactive routing protocols respect

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PacketLossinMobileAdHocNetworks

YiLu,YuhuiZhong,andBharatBhargava

CenterforEducationandResearchinInformationAssuranceandSecurity

and

DepartmentofComputerSciences

PurdueUniversity,WestLafayette,IN,47904,USA.

Email:{yilu,zhong,bb}@cs.purdue.edu.

Abstract—Weinvestigatepacketlossinmobileadhocnetworksviasimulation.Ad-hocon-demanddistancevec-tor(AODV)anddestination-sequenceddistancevector(DSDV)arechosenasrepresentativesoftheon-demandandproactiveroutingprotocolsrespectively.Theeffectsofcongestionandmobilityinvariousnetworkcontextsareexplored.TheresultsindicatethatDSDVloses10%to20%morepacketsthanAODVdoesforUDPtraf c.ForTCPtraf c,thepacketlossforDSDVisahalfofthatforAODV.MobilityisthedominantcauseforAODV,whichisresponsibleformorethan60%oftotalpacketloss.ForDSDV,morethan50%oftotalpacketlossiscongestion-related.Sampledatashowsthatthepacketlossdistributionovertimeisbursting,whichmakesthetraditionPoissonframeworkunsuitableformodellingit.Preliminaryresultsexhibitself-similarpatternthatleadsustobelievethatfractalmodelispromisingtodescribepacketlossinadhocnetworks.Thisworkprovidesguidelinesforthedesignofroutingand owcontrolalgorithmsandinsightsinchoosingproperparametersinfuturesimulationandanalyticstudies.

IndexTerms—adhocnetwork,packetloss,routingprotocol,congestion,mobility

I.INTRODUCTION

Throughputisgenerallyacceptedasoneofthemostimportantmetricstoevaluatetheperformanceofaroutingprotocol.Severalsimulation-basedperformancecomparisonshavebeendoneforadhocroutingprotocolsintherecentyears.S.R.Dasetal.evaluateperformanceofadhocroutingprotocolsbasedonthenumberofcon-versationspermobilenode[1].Theperformancecom-parisonoftwoon-demandroutingprotocols:dynamicsourcerouting(DSR)[2]andAODV[3]ispresentedin[4].Theperformanceoftwolocation-basedroutingprotocolsforadhocnetworksisinvestigatedin[5].Anadaptivedistancevectorroutingalgorithmisproposedin[6],anditsperformance,comparedwithAODVandDSR,isstudied.Althoughvariousthroughputresultsin

ThisresearchissupportedbyCERIAS,NSFgrantsCCR-9901712andCCR-0001788,andCISCOURPgrant.

differentnetworkcontextshavebeenobtained,thecausesforthroughputvariationinadhocnetworkshasnotbeendeeplyunderstood.Packetlossisonethrusttostudythroughput,sincethroughputisdeterminedbyhowmanypacketshavebeensentandhowmanypacketshavelost.Packetlossinwirednetworkhasbeeninvestigated.Forexample,asingleserverqueueingsystemwitha nitebuffercapacityisusedtoanalyzepacketlossprocessesinhigh-speednetworksin[7].Theend-to-endpacketdelayandlossbehaviorsintheInternetarestudiedusingtheUDPechotoolin[8].Theseworktargetatthepacketlossduetobufferover ow(congestion),whichisthemajorlossinwirednetworks.

Packetlossproblemismuchmorecomplicatedinmobileadhocnetworks,becausewirelesslinksaresubjecttotransmissionerrorsandthenetworktopologychangesdynamically.Apacketmayloseduetotrans-missionerrors,noroutetothedestination,brokenlinks,congestions,etc.Theeffectsofthesecausesaretightlyassociatedwiththenetworkcontext(e.g.,hostmobility,numberofconnections,traf cload,etc.).Evenbuildinganapproximatemodeltoanalyticallyevaluatepacketlossisdif cult.Weinvestigatetheproblemviasimula-tions.Dataisgatheredfrommorethan1000individualexperimentstoestimatethedesiredtruecharacteristicsofpacketlossinadhocnetworks.

Inmobileadhocnetworks,wirelesslinktransmissionerrors,mobility,andcongestionaremajorcausesforpacketloss.Packetlossduetotransmissionerrorsisaffectedbythephysicalconditionofthechannel,theterrainwherenetworksaredeployed,etc.Theycannotbeeliminatedorreducedbyimprovingtheroutingpro-tocols.Thispaperonlyaddressescongestion-relatedandmobility-relatedpacketloss.Congestioninanetworkoccurswheneverthedemandsexceedthemaximumcapacityofacommunicationlink,especiallywhenmul-tiplehoststrytoaccessasharedmediasimultaneously.Mobilitymaycausepacketlossindifferentways.Apacketmaybedroppedatthesourceifaroutetothedestinationisnotavailable,orthebufferthatstores