IEEE80211ACIntroduction

GigabitWirelessLAN:Enhancementsin802.11acEldadPerahia,Ph.D.,IntelCorporation,[e-mail],Apple,[e-mail]2012Outline•Introduction–History–Usagemodels–PAR–Enhancements–Channelization•PHY–Waveformdesign–Packetstructure–PHYTransmitterflow–Downlinkmulti-userMIMO–VeryHighThroughput(VHT)waveformPreamble•MAC–Coexistenceinwiderchannels–Channelaccessinwiderchannels–Dynamicbandwidthoperation–Aggregation•DLMU-MIMO2EarlyHistory•VeryHighThroughputStudyGroup(VHTSG)–BeganinMay2007asaprecursortostartingtaskgroup,inwhichpurposeandscopeoftaskgroupweredefined–StartedinitiallytoaddressVeryHighThroughputfor6GHzIMT-Advancedoperation–IMT-Advancedobjectivewasdropped–Focusfor6GHzshiftedtoenhancing802.11nin5GHzband–6GHzPARapprovedinSept20083Wi-FiAllianceVHTUsageModels[6]Category#UsageModel1.WirelessDisplay1aDesktopStorage&Display1bProjectiontoTVorProjectorinConfRom1cInroomGaming1dStreamingfromCamcordertoDisplay1eBroadcastTVFieldPickUp1fMedicalImagingSurgicalProcedureSupport2.DistributionofHDTV2aLightlycompressedvideostreamingaroundhome2bCompr.videostreaminginaroom/t.o.home2cIntraLargeVehicle(e.g.airplane)Applications2dWirelessNetworkingforSmallOffice2eRemotemedicalassistance3.RapidUpload/Download3aRapidSync-n-Gofiletransfer3bPicturebyPictureviewing3cAirplanedocking3dMovieContentDownloadtocar3ePolice/SurveillanceCarUpload4.Backhaul4aMulti-MediaMeshbackhaul4bPointtoPointbackhaul5.OutdoorCampus/Auditorium5aVideodemos/telepresenceinAuditorium5bPublicSafetyMesh6.ManufacturingFloor6aManufacturingfloorautomation4CompressedVideoStreamingaroundaHouse•Pre-Conditions:•UserhasoperationalWLANnetworkwhichincludesaTVwithwirelesscapabilities,aDVRwithwirelesscapabilities,andanAPassociatedwiththeWLANthatisnotinthesameroomasthegamemachineandTV.•Application:•UsercandisplaytheoutputoftheDVRwirelesslyontheTVusingavideocodeclikeMotion2000JPEGthatcompressesvideo.5RapidSync-and-Go•Pre-Conditions:•UserhasWLANconnectivitybetweenaPC,PDA,cellphone,acamcorder,andacamera.•Application:•Usercansyncmoviesto/fromthecamcorderandtransferthepicturefiles.AnMPEG4videofileof1GBytetakes8secondsoverasinglehop1Gbpslink.200jpeg(picture)filesof10Mbytetakeslessthan30secondsovera1Gbpssinglehoplink.Jitteranddelayarenotcritical.Instead,thekeymetricistheuser’stimespenttodoatransfer.Lessthan1minuteisacceptable.1-5minutesmaybeacceptable.Morethan5minutesisnotacceptable.6WirelessI/O•Pre-Conditions:•UserhasoperationalWLANnetworkforInternetaccessandgeneraldatanetworking.ThewirelessnetworkusedforstorageanddisplaymayormaynotbepartoftheotheroperationalWLANnetwork.E-NetE-NetWirelessDockApplication:UsercanwirelesslydisplaytheoutputofthecomputertomonitororTVusinguncompressedvideo.Usercanwirelesslystoredatafromacomputertoaharddrive.Thedatabeingstoredtransfersat~1Gbps,jitteris200msec,delayis200msec,10E-5PER.7802.11acProjectAuthorizationRequest(PAR)•PARrequiresthattheamendmentsupportsinglelinkthroughputofatleast500Mbps•802.11acmustsupportmulti-stationthroughputofatleast1Gbps•Operationin2.4GHzisexcluded•MusthavebackwardcompatibilityandcoexistencewithlegacyIEEE802.11devicesinthe5GHzunlicensedband8RecentHistory•TaskgroupstartedNov2008•Taskgroupdocuments–SpecificationFramework–FunctionalRequirements&EvaluationMethodology–Amendmentto11nChannelModel–UsageModels•Draft3.0approvedJune2012,willprobablybetheversionusedforWFAcertification•Timelinegoingforward–InitialSponsorBallot:plannedforMarch2013–RecirculationSponsorBallot:plannedforMay2013–FinalWorkingGroupApproval:plannedforNovember2013–RevCom&StandardsBoardFinalApproval:plannedforFebruary20149DifferentPhysicalLayers802.11,a,b,g,n,ac802.11802.11b802.11a802.11g802.11n802.11acAccessTechnologyDSSSDSSS/CCKOFDMOFDMSDM/OFDMMU+SDM/OFDMDataRate(Mbps)1,2Upto11Upto54Upto54Upto600Upto6933FrequencyBand(GHz)2.42.452.42.4and55ChannelBandwidth(MHz)2222202220and4020,40,80,16010PHYDataRateImprovementin802.11110100100010000dot11(2.4GHz)11b(2.4GHz)11a(5GHz)/11g(2.4GHz)11n(2.4/5GHz)11ac;4ss(5GHz)11ac;8ss(5GHz)20/25MHz40MHz80MHz160MHz11NewFeaturesandEnhancementsProposedforIEEE802.11ac•Widerbandwidth–80MHzchannelwidth–160MHzchannelwidth–Non-contiguous160MHz(80MHz+80MHz)•Modulation,coding,andspatialstreams–256QAM,rate=3/4–256QAM,rate=5/6–Upto8streams•DownlinkMulti-UserMIMO(DLMU-MIMO)•Increasedaggregatesizelimits•Enhancementtocoexistencemechanisms12Mandatoryvs.Optional802.11nPHYFeaturesBasicMIMO/SDM20MHz;64QAMrate5/6;56tones1,2*spatialstreams2*,3,4spatialstreams40MHz,114tonesTransmitBeamformingConvolutionalCodeLowDensityParityCheckMandatoryOptionalSpaceTimeBlockCode½GuardIntervalMixedFormatPreambleGreenFieldPreambleThroughputEnhancementInteroperabilityw/LegacyRobustnessEnhancement*2spatialstreamsmandatoryforAPonly13Modificationsin802.11acto802.11nFeatures•STBC–onlyfor2x1,4x2,6x3,8x4–No3x2or4x3asin11n•LDPC–Addedblock-interleavingofconstellationsymbolsperstream,perOFDMsymbol•TransmitBeamforming–OnlyExplicitfeedback,noimplicitfeedback–OnlyCompressed-Vfeedback,noUncompressed-V,noCSI–OnlyNDPsounding,nostaggeredsounding–Nounequalmodulation14Mand