22090220010000updatedinterleavingtextandfiguresWord文档格式.docx

22090220010000updatedinterleavingtextandfiguresWord文档格式.docx

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IsabelleSiaud

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Abstract

ClarificationstointerleavertextinDraft2.0,sections8.6.2and8.6.3.Notethatthefigureandtablenumberingisnotinlinewiththedraftnumberingandshouldbemodified.

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8.6.2Sub-carrierallocationmethod

Asub-channeliscomposedof28sub-carriers（24dataand4pilot）.Asub-channelisthebasicunitusedforsub-carrierallocationforbothdownstreamandupstream.Thereisatotalof60sub-channelsperOFDMAsymbol.

Ifpilotinsertionisperformedafterinterleaving（downlink）,interleavingisperformeduponablockofK=NSDCxNscdatasymbols.Afterinterleaving,theKdatasymbolsaresplitintoNscgroupsofNSDCcontiguoussymbols.Pilotsaretheninsertedinaperiodicmannerineachsub-groupfollowingthepilotpatterndefinedinthesection8.6.1.PilotpositionsvarywiththeindexofOFDMAsymbolandsub-carrierindex.Nscsub-channelsassortedwithpilotsassociatedtoablockofK=NSDCxNscdatasymbolsarethendistributedinthefrequencydomaintoformOFDMAsymbols.DL（downlink）sub-carriermappingallocationmethodisillustratedontheFigure115

Foruplinktransmissionpilotinsertionshallbeperformedbeforeinterleaving.Inthiscasearestrictionisenforcedsuchtheblocksizeisatleast7OFDMAsymbolslong,suchthateachsubcarrierisvisitedbyapilottone.Inthiscase,interleavingblocksizeisequaltoK'

=N'

SDCxNSCandsuccessivelyappliedupon7blocksofK'

symbols.Interleavingisthendirectlyfollowedwithsub-channelgenerationresortingfromasplittingofK'

SDCxNSCcontiguoussymbolsintoNscsub-channels.Sub-channelsarethendistributedinthefrequencyandtimedomaintoformOFDMAsymbolsandgeneratethankstoOFDMmodulator,OFDMAsignals.

Sub-carriermappingshallusetheblockinterleavingalgorithmdenotedTurbo-LikeInterleavingwhichisdescribedinthissubclauseandillustratedbyFigure1.AmoredetaileddescriptionofthisinterleavingalgorithmiscontainedinAnnexA

TheinterleavingalgorithmisimplementedbytheTurbo-LikeInterleaver（TLI）whichgeneratesspecificinterleavingpatternsresultingfromtheselectionof4parameters:

∙TheinterleavingblocksizeK

∙The3integerparameters{p,q,j}thatdefinethepermutationruleL（k）,wherekisthelogicalindexbeforeinterleavingandL（k）isthelogicalindexafterinterleaving.TheequationL（k）providestheinputsamplepositionoftheinputsequenceXintheoutputsequenceYlocatedatthek-thposition（Y（k）=X（L（k））

Theiterativestructureofthealgorithmallowsthegenerationofsuitableinterleavingpatterninascalableway.TheTLIgeneratesdedicatedinterleavingpatternsaccordingtothepermutationrule

andtheselectedintegerparameters{p,q,j}foreachblocksizeKasshowninTable2,wherejistheiteration,pistheinterleavingpartitioningsizeandisanintegermultiplicativefactorofK,andqisaninteger.

TheperformanceofL（k）ischaracterizedbytheinterleavingspreadingdepthL（k）betweeninterleavedindicesforakindexdistancebeforeinterleaving,or

Theinterleavingparameters{p,q,j}havebeensettomaximizetheinterleavingspreadingdepthL（k）

Foreachparameterset{p,q,j}andKasinTable2,thepermutationrule

shallbecalculatedas:

where:

FinallyFortheiterationj=1,L（k）isexpressedby:

wehavefortheiterationj:

Figure1TheinterleavingstructureoftheTLI,L（k）

8.6.2.1Downlinksub-carrierallocation

Onthedownstream,60x24=1440dataunitsdestinedtomodulatingsub-carriers（e.g.,2bitsforQPSK,4bitsfor16-QAM,6bitsfor64-QAM）,calleddatasubcarriersforconvenienceareinterleavedusingtheTLIalgorithm.Afterinterleaving,theK=1440datasymbolsaresplitintoNsc=60sub-groupscomposedofNSDC=24subcarriers.Pilotsub-carriersaretheninsertedinaperiodicmanner,4persub-group,followingthepilotpatterndefinedinthesection8.6.1,wherethepilotsub-carrierpositionschangeoveracycleof7OFDMAsymbols.TheblockofK=NSDCxNsc=1440dataunitsalongwiththe240insertedpilotsubcarriersarethenmappedinthefrequencydomaintoformOFDMAsymbols.Thisprocessisrepeatedforeachdataunitinthedownstreamsub-frame.Thesub-carriermappingallocationmethodfordownstreamisillustratedonFigure115andthesupportedblocksizeKandinterleavingparametersareshowninTable2.

Figure115:

Downstreamsubcarriermappingallocation

Thesub-carrierallocationinthedownstreamshallbeperformedusingthefollowingprocedure:

1）Allnullsub-carriersarefirstallocated;

2）EachblockofK=1440datasubcarriersisinterleavedusingtheTLIalgorithm;

3）InterleaveddatasubcarriersaresplitintoNsc=60sub-groupofNSDC=24dataunitmodulation（datasub-carriers）

4）Pilotsubcarriersaretheninsertedwithrespecttothepilotpatternaccordingtotherotatingpilotpatternshowninfigure159,withonepilotbetweenevery6datasubcarriers,periodically.

Figure117showsanexampleofmappingoftheinterleaveddataunitmodulationindicesassignedtosub-carriersinasub-channelbeforepilotinsertion（sub-group）,iethemappingofinputdataunitmodulationinaOFDMAslot.Threesuccessivesub-channelsareshowntoillustratetheinterleavingsub-patterndiversityassociatedwiththeselectedinterleavingpattern{K,p,q,j}={1440,40,2,2}.Theinterleaveddataunitmodulationindexrangeisfrom0toK-1andisrepresentedonthey-axis.EachL（k=l+NSDC*m）datasubcarrierindexisassignedtothel-thdatasub-carrierofthem-thsub-channelSC#mwithm={0,NSC-1}andl=.{0,…,NSDC-1}with{NSC,NSDC}={60,24}.Thesub-carrierindexinasub-channelisrepresentedonthex-axis（beforepilotinsertion）.Sub-patterndiversityisnotmodifiedbypilotinsertionbecausepilotinsertionisrepeated4timesinasub-channelandrepeatedineachsub-channelassociatedtoanOFDMAsymbol.Thedatasubcarrierindexpersub-channelrangesfrom0toNSDC-1=23.

Figure117:

Downstreamsub-channelinterleavingpattern

Figure162showsanexampleallocationforthefirstOFDMAsymbolinaburst,wherePisaPilotsubcarrier,

andL（x）,representsthelocationofthedatasubcarrierafterbeforepermutation:

Figure162ExampleallocationsforthefirstOFDMAsymbolinaburst

8.6.2.2UplinkSub-carrierallocation

Ontheupstream,twosub-channelsarereservedforopportunisticorscheduledcontrolsignaling（i.e.,Ranging/BWRequest/UCSbursts）usingthepre-determinedtoneindicesshowninTable231aftertheappropriatetoneoffsethasbeenappliedasindicatedbelow.Whenthesesub-channelsarenotusedforcontrolsignaling,theycanbeusedfordata.Insuchcase,thepilotsubcarriersarelogicallyallocatedasshowninFigure159andthenmappedtotheappropriatetoneindices.

Fortheremaining58sub-channels,pilotsubcarrierinsertionshallbeperformedbeforeinterleaving.Theupstreamburstsizeisatleast7OFDMAsymbolslong,sothateachsubcarrierisvisitedatleastoncebyapilottone.Inthiscase,interleavingblocksizeshallbeequaltoK'

SDCxNSC（60-2）x（24+4）=1624.Interleavingshallthenbedirectlyfollowedwithsub-channelgenerationresortingfromasplittingofthe1624contiguouslogicalsubcarriersinto58sub-channels.Thesesub-channelsarethendistributedinthefrequencyandtimedomainbyskippingoverthe56subcarriersofthetwofirstsub-c