现代通信系统空时编码技术课件.ppt

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1、现代通信系统平坦准静态瑞利信道下的空时编码技术Withr－CSIdiversity:STBCSTTCmuxplexing:BLASTWithoutCSIUSTCTradeoff：LDCWhymultipleantennas????FrequencyandtimeprocessingareatlimitsSpaceprocessingisinterestingbecauseitdoesnotincreasebandwidthAdaptiveAntennasinterferencecancellationPhasedarrayrangeextension,interferenc

2、ereductionMIMOSystems(diversity)”Specular”channels”Scattering”channelsoutdoorindoormultipathpropagationandtimevariationsfadingTimeselectivefading(duetoDopplerspread)Spaceselectivefading(duetodelayspread)abcdefghijklmnopqFrequencyselectivefading(duetodelayspread)FadinginTime,FrequencyandSp

3、aceFrequencyselectivefading(duetodelayspread)SignalingoverFadingWirelesschannelsFrequencydiversityTimediversity:Channelcodingandinterleaving.AntennadiversitydiversitytechniquesaeimqbfjncskodhlpChannelcodingDifferenttechniques:linearblockcodes(Hamming,Hadamard,Golay,BCH,etc.)convolutionalco

4、descodeconcatenation(parallel,serial,productcodes,etc.)turbocodestrelliscodedmodulationturbocodedmodulationAsophisticatedformoftimediversityCombinedspaceandtimediversitymultipletransmitandreceiveantennasareused.robusttovariationsofthechannel.highspectralefficienciescanbeachieved.Space-time

5、Codes:Combinationofchannelcoding/modulationwithmultipleantennas.EncodergeneratesMelementarysignalstobetransmittedsimultaneously.？IfCSIisavailableatrecieverSpace-timetrelliscodesSpace-timeblockcodesTurbocodedmodulationwithantennadiversityLayeredSpace-TimeCodes,i.e.,BLASTIfCSIisavailableatre

6、ceiverUnitarySpace-timeModulationInitialAssumptionsFlatfadingchannel(Bcoh>>1/Tsymb)Slowlyfadingchannel(Tcoh=1/fd>>Tsymb)nrreceiveandnttransmitantennasNoiselimitedsystem(noCCI)ReceiverestimatesthechannelperfectlyWeconsiderspacediversityonlyTheChannelEigenvaluesOrthogonalchannelsHH†=I,1=2=

7、…=m=1Capacityincreaseslinearlywithmin(nr,nt)AnequalamountofpowerPT/ntisallocatedtoeach”pipe”TransmitterReceiverExample:RayleighfadingchannelHijCN(0,1)nr=1nr=ntOrderedeigenvaluedistributionfornr=nt=4case.STBC概念：满速率分集增益定义满分集增益DiagramofBlockSTCTransmissionDataS