ASurveyonChannelEstimationTechniquesBasedonPilot基于导频信道估计技术的研究

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1、ASurveyonChannelEstimationTechniquesBasedonPilotArrangementinOFDMSystemsbyMustafaErgenAuthors:SinemColeri,MustafaErgen{csinem,ergen}@eecs.berkeley.eduBerkeleyWebOverWirelessGroupUniversityofCaliforniaBerkeleyOutlineMotivationforOFDMOFDMSystemArchitectureChannelEsti

2、mationTechniquesPerformanceAnalysisConclusionMotivationforOFDMDisadvantagesofFDMABadSpectrumUsageDisadvantagesofTDMAMultipathDelayspreadproblemOFDM:UseofFrequencySpectrumEfficientuseofspectrumOverlapinfrequencyspectrumofsubcarriersNullpointofallothersubcarriersatthece

3、nterfrequencyofanyparticularsubcarrierFrequencyspectrumofthesubcarriersMultipathDelaySpreadMulti-pathdelayspreaddefinitionTimespreadbetweenthearrivalofthefirstandlastmultipathsignal,seenbythereceiver.Receivedradiosignalconsistingofadirectsignal,plusreflectionsfromobje

4、ctsMulti-pathdelayspreadeffectInter-SymbolInterference(ISI)whenthedelayedmultipathsignaloverlapswiththesymbolsfollowingitOFDM:EliminatingISICyclicPrefixPrependthelastpartofthesignaltothebeginningofthesignalDurationoftheCPlargerthanmultipathdelayspreadOrthogonalityofth

5、ecarriersnotaffected.OFDMOverviewDivideshigh-speedserialinformationsignalintomultiplelower-speedsub-signals.Transmitssimultaneouslyatdifferentfrequenciesinparallel.Modulation(BPSK,PSK,QPSK,16QAM,…).Pilotsubcarriersusedtopreventfrequencyandphaseshifterrors.BenefitsofOF

6、DMHigherdataratesOverlapofsubcarriersLowerbandwidththanspreadspectrum.HighspectralefficiencyLowermulti-pathdistortionUsageofcyclicprefixOurOFDMSystemAssumptionsUsageofcyclicPrefixImpulseresponseofthechannelshorterthanCyclicPrefix.Slowfadingeffectssothatthechannelistim

7、e-invariantoverthesymbolinterval.RectangularWindowingofthetransmittedpulsesPerfectSynchronizationoftransmitterandreceiverAdditive,white,GaussianchannelnoiseSystemArchitecture-11765432SystemArchitecture-2InputtoTimeDomainGuardIntervalChannelGuardRemovalOutputtoFrequenc

8、yDomainOutputChannelEstimationICIAWGNChannelEstimatedChannelPilotArrangementBlockTypeAllsub-carriersreservedforpilotswitaspe