ieee802.11a無線局域網(wǎng)基于per的鏈路自適應(yīng)算法的研究

1、東北大學(xué)碩士學(xué)位論文IEEE802.11a無線局域網(wǎng)基于PER的鏈路自適應(yīng)算法的研究姓名：楊關(guān)成申請學(xué)位級別：碩士專業(yè)：通信與信息系統(tǒng)指導(dǎo)教師：劉書生20060101東北大學(xué)碩士學(xué)位淪文ABSTRACTAStudyOfTheLinkAdaptationAlgorithmForIEEE8021laAbstractRecently，withtheintroductionofthehighspeedWLANphysicallayer，link

2、adaptationtodynamicallyselectthePHYmodehasbeenrecognizedasaneffectivewaytoimprovethesystemthroughput，butthelinkadaptationmechanismisnotspecifiedinthestandards。Themechanismtoselectoneoutofmultipleavailabletransmissionrate

3、satagiventimeisreferred’|toaslinkadaptationandtheeffectivenessoftheimplementedlinkadaptationschemecanaffectthesystemperformancesignificantly。Inthescheme，themainissuesarethechoiceoftheparametertobeusedforthelinkestimation

4、(egPacketerrorrate，signaltonoiseratio，receivedsignalstrength，carriertointerferenceratio，etc)，andhowtoselecttheappropriateratefrommeasurelncntsoftheselectedparameter。Inthispaper，withstudyingthelinkadaptationalgorithmbased

5、onPERandthesystemperformanceofIEEE8021laPHY，anoptimumthresholdschemeispresentedinsteadofallexistingfixedthresholdscheme。Simulationresultsindicatethattheoptimumthresholdschemeisbetterthanotheralgorithmsintermofthroughput。

6、Then，wepresentagenericmethodtoanalyzethethroughputperformanceofan80211aDCFsystemandderiveaclosedformexpressionoftheexpectedthroughput。Inordertoachievethebestsystenathroughputunderacertainchannelcondition，weapplythePERthr

7、esholdschemeintothesystemof1EEE8021laDCF。TherearetwoinstancesingettingthePERthreshold，oneisoptimumPERthresholdscheme，theotheristhechangedPERthresholdscheme。Thefirstschemeissimpleandeasytodeploy，butitassumethechannelcondi

8、tionisconstantovertheMSDUdeliveryperiodincludesalltheretransmissionsandthePHYmodecannotbechangedforalltheretransmissions，sothisschemecannotadaptquicklytothefast—changingwirelesschannel。BaseoDrecognizingthelimitationsofth

9、eoptinmmPERthresholdscheme，thenweproposeachangedPERthresholdscheme。ThisschemeprovideasetofchangedPERthresholdforeachtransmissionorretransmission，sothewirelessstationCarladaptthePHYmodeforthenexttransmissionattemptifthere