A new approach to channel access scheduling for Ad Hoc networks

Three types of collision-free channel access protocols for ad hoc networks are presented. These protocols are derived from a novel approach to contention resolution that allows each node to elect deterministically one or multiple winners for channel access

ANewApproachtoChannelAccessScheduling

forAdHocNetworks

ComputerScienceDepartment

UniversityofCaliforniaSantaCruz,CA95064

LichunBao

ComputerEngineeringDepartment

UniversityofCaliforniaSantaCruz,CA95064

J.J.Garcia-Luna-Aceves

baolc@soe.ucsc.edu

ABSTRACT

Threetypesofcollision-freechannelaccessprotocolsforadhocnetworksarepresented.Theseprotocolsarederivedfromanovelapproachtocontentionresolutionthatallowseachnodetoelectdeterministicallyoneormultiplewinnersforchannelaccessinagivencontentioncontext(e.g.,atimeslot),giventheidenti ersofitsneighborsoneandtwohopsaway.Thenewprotocolsareshowntobefairandcapableofachievingmaximumutilizationofthechannelbandwidth.Thedelayandthroughputcharacteristicsofthecontentionresolutionalgorithmsareanalyzed,andtheperformanceofthethreetypesofchannelaccessprotocolsisstudiedbysimulations.

jj@soe.ucsc.edu

1.INTRODUCTION

Channelaccessschemesforadhocnetworkscanbecontention-basedorscheduled.Theadvantageofcontention-basedschemesisthattheyarerelativelyeasytodeploy;thishasresultedinmanycontention-basedschemesforadhocnetworksbeingproposedbasedoncarriersensemultipleaccesswithcolli-sionavoidance(CSMA/CA),andthesuccessoftheIEEE801.11(b)standardforwirelesslocalareanetworks[7].Collision-avoidanceschemesareattractiveforadhocnetworks,be-causetheyattempttoeliminatecollisionsofdatapackets,whichdegradenetworkperformance.However,collision-avoidanceschemescannotpreventcollisionsofdatapack-etsresultingfromnear-farphenomena,fading,andcapturee ectsonthechannel[12,14].Inaddition,itisdi culttoprovidequalityofserviceorfairnesswiththesechannelaccessschemes.Thispointstotheneedforchannelaccessmethodsbasedonscheduling.

Scheduledaccessschemesprearrangeornegotiateasetoftimetablesforindividualnodesorlinks,suchthatthetrans-missionsfromthesenodesorontheselinksarecollision-free

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