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:100729513(2002)04200132043G,(,210003):(TD:transmitdiversity)3(3G)cdma2000WCDMA,,:;;:TN929.533:A,,:a.,,,;b.;c.[1,2],,,,,,IMT22000CDMAcdma2000WCDMA[3,4],13G:a.,;b.1.1[5]12(OTD:orthogo2naltransmitdiversity),b[n],xoxe,s1s2s1=xeWk(1),s2=xoWk(2)Wk(1)Wk(2)128Walsh()r=h1s1+h2s2+h1h2,Walsh184Vol118No1420028JiangsuCommunicationTechnologyAug12002:2002203213:(1978),,,,;(1942),,,,©1995-2003TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.256chipWalsh,256/2=128,1.2(space2timecoding),,L:Dc=C(1)kC(2)kC(L)kC(1)k+1C(2)k+1C(L)k+1C(1)k+l-1C(2)k+l-1C(L)k+l-1,,;Cniin,CDck,(k+l-1),l,l,l,;,l1LLL,,122()[6]:xoxe-xe3xo3,xoxe()3,()H,xoxe1.2.1(STTD)[3]STTD(space2timetransmitdiversity),3GPP[3]xoxe,s1s2:s1e=xoW,s2e=xe3W,s1o=xeW,s2o=-xo3W,WWalsh(2)rero=h1xoW+h2xe3Wh1xeW+h2xo3W+eo^xe^xo=(h23re)3+h13roh13re-(h23ro)31.2.2(STS)[7]STS(space2timespreading)WalshSTTD1.1,:S1=xeWk(1)-xo3Wk(2)S2=xoWk(1)+xe3Wk(2)Wk(1)Wk(2):^xe=rWk(1)h13+(rWk(2)h23)3,^xo=rWk(1)h23-(rWk(2)h13)3^xe,^xoSTSSTTDOTD,23GBS()MS(),MSBS412002©1995-2003TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.,MS,MS2.1(STD)STD(selectivetransmitdiversity)STTDMS,BS,BS2.2(TxAA)TxAA(transmitadaptivearrays)MS,BSMS,33,BSh1(t)h2(t),w1w2,b[n],u(t),MSy=[h1h2]w1w2b+=HWb+,,W=HH/(HHH),,H,HHH,P1P2H,MS,BSSTDTxAA,[0,1][1,0]TxAA,[5]RSNR|h1|2+|h2|2|h1|2+|h2|22EcNo=(|h1|2+|h2|2)EcNoEc/N0,1.2.1,,STTD[5]RSNR|h1|2+|h2|22EcNo,,STTDSNRTxAASNR2.32.3.1,,,WCDMA,1,2,1bit(,1)4bit(3bit,1bit,2)2.3.2FEC(),BSMS,MS,,,,,2.3.3MS,BSAR(),AR,,3,514,:3G©1995-2003TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.(FER)1%Ec/Ior()14,TxAA,,TxAA12/(kbit/s)9.6/(Mchip/s)1.2288Walsh/(chip)128/GHz21/4,K=9(Ec/Ior)/dB27/Hz800/(%)4TxAA/%5/PCB2TxAA/Hz800:PCB43G,,,,,:[1]THOMPSONJS,GRANTPM,BULGREWB.Downlinktransmitdi2versityschemesforCDMAnetworks[A].ProcofIEEEVehicularTechnologyConf[C].AmsterdantheNetherlands:[s.n.],1999.138224386.[2]TAROKHV,JAFARKHANIH,CALDERBNAKAR.Space2Timeblockcodingforwirelesscommunication:Performanceresults[J].IEEEJSelectAreasCommun,1999,17(3):451460.[3]3GPP2IS220002A,Physicallayerstandardforcdma200spreadspec2trumsystems,releaseA[S].[4]3GPPTS25.211,Physicalchannelsandmappingoftransportchannelsontophysicalchannels(FDD)[S].[5]ROHANIK,HARISONM,KUCHIK.Acomparisonofbasestationtransmitdiversitymethodsforthirdgenerationcellularstandards[A].procofIEEEVTC99.TexasUSA:[s.n.],1999.3512355.[6]ALAMOUTIS.M.Asimpletransmitdiversitytechniqueforwirelesscom2munications[J].IEEEJSelectAreasCommun,1998,16(10):1451258.[7]BHOCHWALD,THOMASLM.AtransmitterdiversityschemeforwidebandCDMAsystembasedonspace2timespreading[J].IEEEJSelectAreasCommun,2001,19(1):48260.TransmitDiversityintheThirdGenerationCellularSystemWANGZhen2yu,QIYu2sheng(DepartmentofCommunicationsEngineering,NanjingUniversityofPostsandTelecommunications,Nanjing21003,China)Abstract:Transmitdiversity(TD)isoneofthekeycontributingtechnologiesto3GsystemsWCDMAandcdma2000.Itcanimprovetheperformanceofsystembyutilizingtheindependentfadingsignalsemanat2ingfromspacedtransmitantennas.ThispaperdescribestheconceptoftransmitdiversityandexplainsthefeaturesandperformanceofselectedTDtechniques.Keywords:transmitdiversity;space2timecode;widebandcodedivisionmultipleaccess612002©1995-2003TsinghuaTongfangOpticalDiscCo.,Ltd.Allrightsreserved.