无线通信基础（双语）教学课件.ppt

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1、ReviewofLastClass3.3.2CoherentReceptioninaFlatSlowRayleighFadingChannel3.3.1CoherentReceptioninanAWGNChannelReviewofLastClassFlatfadingProblem:errorrateMitigation:Interleaving;Errorcorrectioncoding;DiversitytechniquesFrequencySelectiveFadingProblem:ISIanderrorratesMitigation:E

2、qualization;OFDM;Directionalantenna;SpreadspectrumOthermechanismtocombatchannelimpairments12345678910111213141516171819202122232425FlatFadingchannel54321109876151413121120191817162524232221modulatoroutdemodulatorin…7221161161…incoderoutdecoderInterleavingandErrorcorrectioncodi

3、ngOthermechanismtocombatchannelimpairmentsFlatFadingchannel1modulatorindemodulatoroutFlatFadingchannel2DiversitytechniquesOthermechanismtocombatchannelimpairmentsFrequencySelectiveFadingTsinoutTsTsEqualizationOthermechanismtocombatchannelimpairmentsOFDMandDirectionalantennaOth

4、ermechanismtocombatchannelimpairmentsMIMOOthermechanismtocombatchannelimpairmentsmodulatorindemodulatoroutChapter3----Lecture4SpreadSpectrumCommunication(1)3.4SpreadSpectrum3.4.2SpreadingCodes3.4.1Spread-SpectrumPrinciples3.4.3Direct-SequenceSpreadSpectrum3.4.4Frequency-Hopped

5、SpreadSpectrum3.4.5CodeDivisionMultipleAccess3.4SpreadSpectrum3.4.2SpreadingCodes3.4.1Spread-SpectrumPrinciples3.4.3Direct-SequenceSpreadSpectrum3.4.4Frequency-HoppedSpreadSpectrum3.4.5CodeDivisionMultipleAccess1、Spread-SpectrumPrinciplesIntroductionDefinitionofSpreadSpectrumW

6、hySpreadSpectrum?Althoughbandwidthisavaluablecommodityinwirelesssystems,increasingthetransmitsignalbandwidthcansometimesimproveperformance.Spreadspectrumfirstachievedwidespreaduseinmilitaryapplicationsbecauseofitsinherentpropertyofhidingthespreadsignalbelowthenoisefloorduringt

7、ransmission,itsresistancetonarrowbandjammingandinterference,anditslowprobabilityofdetectionandinterception.Introduction3.4.1Spread-SpectrumPrinciplesForcommercialapplication,thenarrowbandinterferenceresistancehasmadespreadspectrumcommonincordlessphones.TheISIrejectionandbandwi

8、dth-sharingcapabili-tiesofspreadspectrumareverydesirableincel