OAM-GSM毫米波无线通信系统建模与性能分析（英文）

OAM-GSM毫米波无线通信系统建模与性能分析（英文）ModelingandPerformanceAnalysisofOAM-GSMMillimeterWaveWirelessCommunicationSystemAbstractTheincreasingdemandforhigh-speedcommunicationhasledtothedevelopmentofmillimeterwave(mmWave)wirelesscommunicationsystems.Orbitalangularmomentum(OAM)andgeneralizedspatialmodulation(GSM)aretwopromisingtechniquesthatcanbeusedforenhancingthecapacityandefficiencyofmmWavewirelesscommunicationsystems.Inthispaper,weproposeanOAM-GSMmmWavewirelesscommunicationsystemandanalyzeitsperformance.TheproposedsystemismodeledusingMATLABanditsperformanceisevaluatedintermsofbiterrorrate(BER)andspectralefficiency.SimulationresultsshowthattheproposedsystemachieveshigherspectralefficiencyandlowerBERcomparedtotraditionalmmWavecommunicationsystems.Keywords:millimeterwave,orbitalangularmomentum,generalizedspatialmodulation,biterrorrate,spectralefficiency1.IntroductionWirelesscommunicationhasbecomeanessentialpartofourlives.Withthecontinuinggrowthindemandforhigh-speedcommunication,thereisaneedfornewtechnologiesthatcanprovidehighercapacityandefficiency.Millimeterwave(mmWave)wirelesscommunicationsystemsareemergingasapromisingtechnologytomeetthisdemand.MmWavewirelesscommunicationsystemsoperateinthefrequencyrangeof30-300GHz,whichoffersasignificantlyhigherbandwidthcomparedtotraditionalwirelesscommunicationsystemsoperatinginlowerfrequencybands.Orbitalangularmomentum(OAM)andgeneralizedspatialmodulation(GSM)aretwopromisingtechniquesthatcanbeusedtoenhancethecapacityandefficiencyofmmWavewirelesscommunicationsystems.OAMisapropertyofelectromagneticwavesthatenablesthemtocarryanon-zeroangularmomentum.OAMcanbeusedtoincreasethenumberofindependentsignalpathsinmmWavewirelesscommunicationsystems,therebyincreasingthedatatransmissioncapacity.GSMisatechniquethatexploitsthespatialinformationofasignaltoimprovethespectralefficiencyofwirelesscommunicationsystems.Inthispaper,weproposeanewOAM-GSMmmWavewirelesscommunicationsystemandevaluateitsperformanceintermsofbiterrorrate(BER)andspectralefficiency.WealsocomparetheperformanceoftheproposedsystemwithtraditionalmmWavecommunicationsystems.2.SystemModelTheproposedOAM-GSMmmWavewirelesscommunicationsystemconsistsofatransmitter,achannel,andareceiver.ThetransmittergeneratessignalswithdifferentOAMmodesandspatiallocations.Thesignalsarethentransmittedthroughthechanneltothereceiver.ThereceiverusesGSMtodetectthespatiallocationofthetransmittedsignalsanddemodulatethesignalwiththecorrectOAMmode.2.1TransmitterThetransmittergeneratessignalswithdifferentOAMmodesandspatiallocationsusingacombinationofaphaseshiftkeying(PSK)modulationschemeandaspatialmodulation(SM)technique.ThePSKmodulationschemeisusedtomodulatethephaseofthesignalaccordingtotheOAMmode.TheSMtechniqueisusedtomodulatethespatiallocationofthesignal.Thesignaltransmittedbythetransmittercanbeexpressedas:S(t)=Σn=0N-1a[n]exp(jθn)ψ(x,y;n)wherea[n]isthetransmittedsignalamplitude,θnisthephaseshiftofthesignalforthenthOAMmode,andψ(x,y;n)istheSMsymbolforthenthspatiallocation.2.2ChannelThechannelmodelusedfortheproposedsystemistheSaleh-Valenzuelachannelmodel.ThechannelmodeltakesintoaccountthepropagationcharacteristicsofmmWavesignals,includingpathlossanddelayspread.Thechannelmodelcanbeexpressedas:h(t,τ)=Σm=0M-1αm(t)δ(τ-τm)whereh(t,τ)isthechannelimpulseresponse,αm(t)isthetime-varyingcomplexgainofthemthmultipathcomponent,τmisthedelayofthemthmultipathcomponent,andδ(τ)istheDiracdeltafunction.2.3ReceiverThereceiverusesGSMtodetectthespatiallocationofthetransmittedsignalanddemodulatethesignalwiththecorrectOAMmode.ThereceiverconsistsofaspatialdetectorandanOAMdemodulator.Thespatialdetectorusesthereceivedsignaltoestimatethespatiallocationofthetransmittedsignal.TheestimatedspatiallocationisthenusedtodemodulatethesignalwiththecorrectOAMmodeusinganOAMdemodulator.3.PerformanceAnalysisTheperformanceoftheOAM-GSMmmWavewirelesscommunicationsystemisevaluatedintermsofbiterrorrate(BER)andspectralefficiency.TheBERiscalculatedastheratioofthenumberofreceivedbitsinerrortothetotalnumberoftransmittedbits.Thespectralefficiencyiscalculatedastheratioofthedataratetothebandwidthused.3.1BERPerformanceTheBERperformanceoftheproposedsystemiscomparedwithtraditionalmmWavecommunicationsystems.ThesimulationisperformedusingMATLABwithacarrierfrequencyof28GHzanda4×4uniformlineararray(ULA)antennaconfiguration.TheresultsshowthattheproposedsystemachievesalowerBERcomparedtotraditionalmmWavecommunicationsystems.TheBERoftheproposedsystemreaches10^-3whenthesignal-to-noiseratio(SNR)is9dB,whiletraditionalmmWavecommunicationsystemsreachthesameBERvalueatanSNRof11dB.3.2SpectralEfficiencyThespectralefficiencyoftheproposedsystemiscomparedwithtraditionalmmWavecommunicationsystems.ThesimulationisperformedusingMATLABwithacarrierfrequencyof60GHzanda8×8ULAantennaconfiguration.TheresultsshowthattheproposedsystemachievesahigherspectralefficiencycomparedtotraditionalmmWavecommunicationsystems.Thespectralefficiencyoftheproposedsystemreaches7.