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Rice衰落信道下选择中继的性能分析与功率分配算法.docx

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Rice衰落信道下选择中继的性能分析与功率分配算法 1.Introduction RicefadingchannelsareatypeofwirelesscommunicationchannelthatischaracterizedbybothadditivewhiteGaussiannoiseandmultipathfading.Insuchchannels,thesignalreceivedatthereceiverisseverelydegradedduetothepresenceofalargenumberofchannelinterferers.Onewaytoimprovetheperformanceofsuchchannelswhenthedirectlinkisunavailableisbyusingrelays.Inthispaper,wewillfocusontheperformanceanalysisandpowerallocationalgorithmforselectingarelayinaRicefadingchannel. 2.PerformanceAnalysis InaRicefadingchannel,thesignalisaffectedbybothline-of-sightandnon-line-of-sightcomponents.Thisresultsinacomplexchannelwithanon-uniformdistributionofthesignalstrength.Insuchachannel,itispossibletouserelaystoimprovethequalityofthesignalbyamplifyingandrepeatingit.Thequestionthenbecomeshowtoselectarelaythatcanbestimprovethesignal.Onewaytoanswerthisquestionisthroughtheuseofperformanceanalysis. Thereareseveralparametersthatcanbeusedtoevaluatetheperformanceofarelay.Theseincludethesignal-to-noiseratio(SNR),thebiterrorrate(BER),andthecapacity.SNRrepresentstheratioofthesignalpowertothenoisepower,andiscommonlyusedinwirelesscommunicationstoquantifythequalityofthesignal.BERrepresentstheprobabilityofanerrorinthetransmissionofabitofdata,andisanimportantparameterinevaluatingthereliabilityofacommunicationsystem.Capacityrepresentsthemaximumamountofdatathatcanbetransmittedoverachannel,andisanimportantparameterinevaluatingtheefficiencyofacommunicationsystem. Toevaluatetheperformanceofarelay,itisnecessarytoconsiderthechannelconditionsandtherelaylocation.Forexample,inaRicefadingchannel,itisimportanttoconsidertheline-of-sightandnon-line-of-sightcomponentswhenselectingarelay.Inaddition,thelocationoftherelaycanalsoaffecttheperformance,asthesignalstrengthcanvarydependingonthedistancebetweentherelayandthesourceanddestination. 3.PowerAllocationAlgorithm Oncearelayhasbeenselected,itisimportanttoallocatetheappropriateamountofpowertotherelaytooptimizetheperformanceofthesystem.Thisrequiresapoweralloca