直序扩频通信-matlab仿真DIRECT-SEQUENCE-SPREAD-SPECTRUM-TECHNIQUES.doc

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1、Lab2DirectSequenceSpreadFrequencyTechniques直序扩频通信仿真ContentAbstract-------------------------------------------------------------------------------------------3ExperimentBackground----------------------------------------------------------------------3ExperimentProcedure

2、------------------------------------------------------------------------5AnalysisandConclusion---------------------------------------------------------------------10Reference--------------------------------------------------------------------------------------10Append

3、ix----------------------------------------------------------------------------------------121.AbstractTheobjectiveofthislabexperimentistolearnthefundamentalsofthedirectsequencespreadspectrumandcodedivisionmultipleaddresstechniques.Togetfamiliarwiththedirectsequencespr

4、eadspectrummodulatoranddemodulator.Andthedirectsequencespreadspectrumsystemcanbeshownas:Figure1.Directsequencespreadspectrumsystem2.ExperimentBackground2.1IntroductionofDirectSequenceSpreadSpectrum[1]Intelecommunications,direct-sequencespreadspectrum(DSSS)isamodulatio

5、ntechnique.Aswithotherspreadspectrumtechnologies,thetransmittedsignaltakesupmorebandwidththantheinformationsignalthatisbeingmodulated.Thename'spreadspectrum'comesfromthefactthatthecarriersignalsoccuroverthefullbandwidth(spectrum)ofadevice'stransmittingfrequency.Figure

6、2.1ProceduretogenerateaDSSSsignal2.2GenerationofDirectSequenceSpreadSpectrumTogenerateaspreadspectrumsignalonerequires:1.AmodulatedsignalsomewhereintheRFspectrum2.APNsequencetospreadit2.3FeaturesofDirectSequenceSpreadSpectrumDSSShassomefeaturesasfollowing:1.DSSSphase-

7、modulatesasinewavepseudorandomlywithacontinuousstringofpseudonoise(PN)codesymbolscalled"chips",eachofwhichhasamuchshorterdurationthananinformationbit.Thatis,eachinformationbitismodulatedbyasequenceofmuchfasterchips.Therefore,thechiprateismuchhigherthantheinformationsi

8、gnalbitrate.2.DSSSusesasignalstructureinwhichthesequenceofchipsproducedbythetransmitterisknownaprioribythereceiver.Thereceiv