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认知Adhoc网络中基于QoS的MAC机制研究.docx

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认知Adhoc网络中基于QoS的MAC机制研究 Abstract Adhocnetworksareapopularresearchtopicinthefieldofwirelesscommunication.Withthegrowinginterestinmultimediaapplications,QualityofService(QoS)hasbecomeanimportantcriterionforevaluatingnetworkperformance.TheMediumAccessControl(MAC)protocolisakeycomponentofAdhocnetworksthatplaysavitalroleinensuringreliablecommunication.Therefore,inthispaper,weinvestigatetheQoS-basedMACmechanisminAdhocnetworks.WefirstintroducetheconceptofAdhocnetworksandthechallengestheypose.WethendiscusstheimportanceofQoSanditsimpactonnetworkperformance.WealsoreviewtheexistingMACprotocolsandtheirlimitationsinprovidingQoSguarantees.Finally,weproposeanovelQoS-basedMACmechanismthatovercomestheselimitationsandenhancestheQoSperformanceofAdhocnetworks. Keywords:Adhocnetworks,QualityofService(QoS),MediumAccessControl(MAC),QoS-basedMACmechanism Introduction Adhocnetworksareself-organizingnetworksofmobiledevicesthatareformedwithouttheneedforanypre-existinginfrastructure.Theyareparticularlyusefulinsituationswherethereisnofixedinfrastructureorwheretheinfrastructureisunreliableordamaged,suchasindisasterreliefoperations,militaryoperations,andemergencysituations.Adhocnetworksarealsousedforcommercialapplications,suchassensornetworks,vehicularnetworks,andmobileadhocnetworks(MANETs). Adhocnetworksposeuniquechallengesduetotheirdynamictopology,limitedbandwidth,andenergyconstraints.Moreover,withtheincreasingpopularityofmultimediaapplications,QoShasbecomeacriticalfactorinevaluatingtheperformanceofAdhocnetworks.QoSreferstotheabilityofanetworktoprovidereliableandpredictabledeliveryofdata,ensuringthatthedatameetscertainperformancerequirements,suchasbandwidth,delay,andjitter. TheMACprotocolisakeycomponentofAdhocnetworksthatdetermineshownodesinthenetworksharethewirelesschannel.SeveralMACprotocolshavebeenproposedforAdhocnetworks,suchasIEEE802.11,IEEE802.15.1,IEEE802.15.4,andDistributedCoordinationFunction(DCF).However,theseprotocolsarenotcapableofprovidingQoSguaranteesinAdhocnetworksduetotheirlimit