认知无线电频谱感知课件.ppt

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1、CHAPTER5.SPECTRUMSENSING1WhatisSpectrumSensing?HowtodetectspectrumholesbytheCOGNITIVERADIOsothatitcanadaptitselftoitsenvironment!!2SpectrumSensingSpectrumSharingSpectrumSensingSpectrumDecisionChannelCapacityPrimaryUserDetectionRFStimuliSpectrumHoleRadioEnvironmentSpectrumMobili

2、tyDecisionRequestTransmittedSignal3CRUser1PrimaryTxPrimaryRxNointeractionbetweenCRuserandPrimaryTx/RxCRusermustrelyonlocallysensedsignalstoinferprimaryuseractivityChannelsfoundoccupiedbyCRuser(Licensedbands1and2)arenowavoidedduringcommunicationbetweenCRsAgeneralCRbasedcommunica

3、tionscenarioCRUser2Licensedband1Licensedband2EFFICIENTWAYTODETECTSPECTRUMHOLES4EFFICIENTWAYTODETECTSPECTRUMHOLES!!DetectprimaryusersthatarereceivingdatawithinthecommunicationrangeofaCRuser.InrealityDifficultforaCRtodetectprimaryuseractivityintheabsenceofinteractionbetweenprima

4、ryusersanditself.RECENTRESEARCHHowtodetectprimaryusersbasedon“localobservation”ofCRusers(fromitsenvironment)5ClassificationofSpectrumSensingTechniquesInterferenceTemperatureManagementTransmitterDetectionSpectrumSensingReceiverDetectionMatchedFilterDetectionEnergyDetectionCyclo

5、stationaryFeatureDetection6TransmitterDetectionCRshoulddistinguishbetweenUsedandUnusedspectrumbands.CRshouldhavethecapabilitytodetermineifasignalfromprimaryuser(transmitter)islocallypresentinacertainspectrum.TransmitterDetectionApproachDetectionofthesignal(weaksignalastheworst

6、case)fromaprimaryuserthroughlocalobservationsofCRusers.7BasicHypothesisModelforTransmitterDetectionThesignalr(t)received(detected)bytheCR(secondary)useriswheren(t)AWGN(AdditiveWhiteGaussianNoise)s(t)TransmittedsignaloftheprimaryuserhAmplitudegainofthechannelH0Nullhypothesis

7、Nolicensedusersignalinacertainspectrumband.H1AlternativehypothesisThereexistssomelicensedusersignal.8TransmitterDetectionThreeschemesaregenerallyusedforthetransmitterdetectionaccordingtothehypothesismodel.MatchedFilterDetectionEnergyDetectionandCyclostationaryFeatureDetectio

8、nTechniquesD.Cabric,S.M.Mishra,andR.W.Brodersen,“Imple