Ad+Hoc上TCP协议分析与改进

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1、ABSTRACTAsthemostwidespreadtransportlayerprotocol，TCPWaSoriginallydesignedfor丘xedwirednetworkandwasonlyfitforit．AdHoeNetworkisadistributednetworkwhichhasnewfeaturesofthelowerlayersthatcouldbewildlydifferentwi也thetraditionalnetwork．TCPCallnotdealwimtheseilewfeaturesSOitsperformancedropsdramaticall

2、y．Asaresult,thekeytoimproveAdHoe’sperformancedependsOneitherTCP’sevolutionofrefitandredesign，01"Onstrenghtheningthefi'agilelowlayersofAdHocitscl￡ThisissueisfocusedOntheAdHoeprotocolstackresearchandretrofit．IEEE802．11DCF,AODVDSRprotocolandTCP—Renoaleselectedillstheprotocolstackoflinklayer,networkl

3、ayerandtransportlayer．ResearchesareconcentratedOiltheexploitingofnetwork’sundevelopedinformation．Themoreusefulinformationthereis，themolecapablethenodesCallbewhenfacingperplexnetworkenvironment．Thebottleneckdetectandeliminatemethod，frameerrorratiobasedlinkstatusevaluateandpredictmechanism，stabilit

4、yfirstroutingmethodforAODVprotocolandsuccessfullyrecievedpacketratiobasedTCPcongestionwindowsmodifymechanismareproposed．TheyareallbasedOnminingandusingtheunderlyinginformationofnetwork．(1)ThecompetitionsofAdHoeMAClayerisveryfierceandbottlenecksareeasytoshape．Togivethebottlenecknodesmoreadvantages

5、inchannelcompetition,thebottleneckdetectandeliminatemethodisusedtofindandhelpthesenodes，lettingthemoccupythechannelfasterandeasethetensionofthenetworkbottleneck．(2)Theframeerrorratiobasedlinkstatusevaluateandpredictmechanismevaluateandpredictthechannelqualitywithoutincreasinganynetworkcost．Thisme

6、chanismcangetanaccuratedepictionofthesechannelsandthenlaunchcertainpolicies．(3)BasedOnthismechanism，inthenetworklayer,stabilityfirstroutingmechanismforAODVprotocolchangedthewaythatAODVusedtopickbestIllABSTRACTroute，whichwasroutingbyminimumhops．Thenewmechanismchoosesthemoststableroutewhenroutingan

7、dlaunchesare-routingwhentheMAClayerhaspredictedaneighborvanishing，thusenhancesthestabilityofactivenetworklayerroutesanddecreasesthepossibilityofroutebreakdown，finallyraisestheentirethroughputofthewholenetwork．(4)TCP—Re