Location-aided routing (LAR) in mobile ad hoc networks
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WirelessNetworks6(2000)307–321307
Location-AidedRouting(LAR)inmobileadhocnetworks∗
Young-BaeKoandNitinH.Vaidya
DepartmentofComputerScience,TexasA&MUniversity,CollegeStation,TX77843-3112,USA
Amobileadhocnetworkconsistsofwirelesshoststhatmaymoveoften.Movementofhostsresultsinachangeinroutes,requiringsomemechanismfordeterminingnewroutes.Severalroutingprotocolshavealreadybeenproposedforadhocnetworks.Thispapersuggestsanapproachtoutilizelocationinformation(forinstance,obtainedusingtheglobalpositioningsystem)toimproveperformanceofroutingprotocolsforadhocnetworks.Byusinglocationinformation,theproposedLocation-AidedRouting(LAR)protocolslimitthesearchforanewroutetoasmaller“requestzone”oftheadhocnetwork.Thisresultsinasignificantreductioninthenumberofroutingmessages.Wepresenttwoalgorithmstodeterminetherequestzone,andalsosuggestpotentialoptimizationstoouralgorithms.
1.Introduction
Mobileadhocnetworksconsistofwirelessmobilehosts
thatcommunicatewitheachother,intheabsenceofa
fixedinfrastructure.1RoutesbetweentwohostsinaMo-
bileAdhocNETwork(MANET)mayconsistofhops
throughotherhostsinthenetwork[7].Hostmobilitycan
causefrequentunpredictabletopologychanges.Therefore,
thetaskoffindingandmaintainingroutesinMANETis
nontrivial.Manyprotocolshavebeenproposedformo-
bileadhocnetworks,withthegoalofachievingefficient
routing[6,9,11,13,16,18–20,23,28,30,31,33,35].Theseal-
gorithmsdifferintheapproachusedforsearchinga
newrouteand/ormodifyingaknownroute,whenhosts
move.
Inthispaper,wesuggestanapproachtodecreaseover-
headofroutediscoverybyutilizinglocationinformation
formobilehosts.Suchlocationinformationmaybeob-
tainedusingtheglobalpositioningsystem(GPS)[10,29].
Wedemonstratehowlocationinformationmaybeused
bymeansoftwoLocation-AidedRouting(LAR)proto-
cols[19,20,22]forroutediscovery.TheLARprotocolsuse
locationinformation(whichmaybeoutofdate,bythetime
itisused)toreducethesearchspaceforadesiredroute.
Limitingthesearchspaceresultsinfewerroutediscovery
messages.
Thispaperisorganizedasfollows.Section2discusses
somerelatedwork.Insection3,wedescribeproposed
approachforusinglocationinformationforroutediscov-
eryinMANET.Performanceevaluationofourprotocols
ispresentedinsection4,andseveraloptimizationstoour
basicapproacharedescribedinsection5.Finally,section6
presentsconclusions.
∗ResearchreportedissupportedinpartbyTexasAdvancedTechnologyProgramgrants010115-248and009741-052-C,andNationalScienceFoundationgrantCDA-9529442.1Wewillusethetermshostandnodeinterchangeably.2.Relatedwork
Designofroutingprotocolsisacrucialprobleminmo-
bileadhocnetworks[5,32],andseveralroutingalgorithms
havebeendeveloped(e.g.,[6,9,11,13,16,18–20,23,28,30,
31,33,35]).Onedesirablequalitativepropertyofarouting
protocolisthatitshouldadapttothetrafficpatterns[7].
JohnsonandMaltz[17,18]pointoutthatconventionalrout-
ingprotocolsareinsufficientforadhocnetworks,sincethe
amountofroutingrelatedtrafficmaywastealargepor-
tionofthewirelessbandwidth,especiallyforprotocolsthat
useperiodicupdatesofroutingtables.Theyproposedus-
ingDynamicSourceRouting(DSR),whichisbasedon
on-demandroutediscovery.Anumberofprotocolopti-
mizationsarealsoproposedtoreducetheroutediscov-
eryoverhead.PerkinsandRoyer[31]presenttheAODV
(AdhocOndemandDistanceVectorrouting)protocolthat
alsousesademand-drivenrouteestablishmentprocedure.
TORA(Temporally-OrderedRoutingAlgorithm)[27,28]is
designedtominimizereactiontotopologicalchangesby
localizingrouting-relatedmessagestoasmallsetofnodes
nearthechange.HassandPearlman[13]attempttocom-
bineproactiveandreactiveapproachesintheZoneRout-
ingProtocol(ZRP),byinitiatingroutediscoveryphaseon-
demand,butlimitingthescopeoftheproactiveprocedure
onlytotheinitiator’slocalneighborhood.Recentpapers
presentcomparativeperformanceevaluationofseveralrout-
ingprotocols[4,8].
ThepreviousMANETroutingalgorithmsdonottake
intoaccountthephysicallocationofadestinationnode.In
thispaper,weproposetwoalgorithmstoreduceroutedis-
coveryoverheadusinglocationinformation.Similarideas
havebeenappliedtodevelopselectivepagingforcellu-
larPCS(PersonalCommunicationService)networks[1].
Inselectivepaging,thesystempagesaselectedsubsetof
cellsclosetothelastreportedlocationofamobilehost.
Thisallowsthelocationtrackingcosttobedecreased.We
proposeandevaluateananalogousapproachforrouting
inMANET.InasurveyofpotentialapplicationsofGPS,
©J.C.BaltzerAG,SciencePublishers308Y.-B.Ko,N.H.Vaidya/Location-AidedRouting(LAR)inmobileadhocnetworks
DommetyandJain[10]brieflysuggestuseoflocationinfor-
mationinadhocnetworks,thoughtheydonotelaborateon
howtheinformationmaybeused.Otherresearchershave
alsosuggestedthatlocationinformationshouldbeusedto
improve(qualitativelyorquantitatively)performanceofa
mobilecomputingsystem[34,36].Metricom’sRicochetis
apacketradiosystemusinglocationinformationforthe
routingpurpose[24].TheMetricomnetworkinfrastructure
consistsoffixedbasestationswhosepreciselocationisde-
terminedusingaGPSreceiveratthetimeofinstallation.
Metricomusesageographicallybasedroutingschemeto