[AAAAA] iterative decoding of binary block and convolutional codes

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1、IEEETRANSACTIONSONINFORMATIONTHEORY,VOL.42,NO.2,MARCH1996429IterativeDecodingofBinaryBlockandConvolutionalCodesJoachimHagenauer,Fellow,ZEEE,ElkeOffer,andLutzPapkeAbstract-Iterativedecodingoftwo-dimensionalsystematicwithfairlysimplecomponentcodesinaninterleavedscheme.convolutionalco

2、deshasbeentermed“turbo”(de)coding.UsingThebasicideaistobreakupdecodingofafairlycomplexlog-likelihoodalgebra,weshowthatanydecodercanheusedandlongcodeintostepswhilethetransferofprobabilitieswhichacceptssoftinputs-includingapriorivalues-anddeliversor“soft”informationbetweenthedecoding

3、stepsguaranteessoftoutputsthatcanhesplitintothreeterms:thesoftchannelandaprioriinputs,andtheextrinsicvalue.Theextrinsicvalueisusedalmostnolossofinformation.Aflavoroftheideacanbeasanapriorivalueforthenextiteration.DecodingalgorithmsinfoundintheworkofBattail,e.g.,[2]-[4].Iterativedec

4、odingthelog-likelihooddomainaregivennotonlyforconvolutionalschemeswith“soft-in/soft-out”decoderswereproposedincodeshutalsoforanylinearbinarysystematicblockcode.[5]-[7].In[6]anEb/Noof1.3dBwasachievedfortheaboveTheiterationiscontrolledbyastopcriterionderivedfrommentionedchannelwithat

5、hree-dimensionalcodeofmoderatecrossentropy,whichresultsinaminimalnumberofiterations.Optimalandsuboptimaldecoderswithreducedcomplexityarecomplexity.Impressivesimulationresultswerepresentedinpresented.Simulationresultsshowthatverysimplecomponent[8]achievinganE,,/Noof0.7dB,althoughwit

6、hahugecodesaresufficient,blockcodesareappropriateforhighratesinterleaverof64500bits,18iterations,andsomeadhoc“fine-andconvolutionalcodesforlowerrateslessthan213.Anytuning”factorsintheBahlalgorithm[9].Thenoveltyin[8]combinationofblockandconvolutionalcomponentcodesiswastheuseofsystem

7、aticfeedbackconvolutionalcodesinthepossible.Severalinterleavingtechniquesaredescribed.Atabiterrorrate(BER)oflo-*theperformanceisslightlyaboveoriterativeschemeandtheintroductionofa“pseudo’‘-randomaroundtheboundsgivenbythecutoffrateforreasonablysimpleinterleaver(scrambler)betweenthet

8、woencoders.Inthepaperblock