ASIC Implementable Synchronizationand Detection Me

ASICImplementableSynchronization-andDetectionMethodsforDirectSequenceSpreadSpectrumWidebandRadioReceiversHenrikOlsonStockholm,August18,1997ElectronicSystemDesign,DepartmentofElectronicsElectrum229,Isafjordsgatan22-26S-16440Kista,SwedenSubmittedtotheSchoolofElectricalEngineering,RoyalInstituteofTechnology,inpartialfulfillmentoftherequirementsforthedegreeofTechnicalLicentiate.AbstractIndirectsequencespreadspectrum(DSSS)technology,thetrendtomovemoreandmorereceiversignalprocessingtothedigitaldomainisasvalidasitisinallotherdigitalradioapplications.Thegoalsare,especiallyontheterminalside,lowpowerandlowcomplex-itywhichinturnrequire“implementationfriendly”algorithms.ThisthesisapproachesthesubjectofimplementableDSSSreceiversaimedatdataratesupto2Mbit/sfromtwodirections.Intheareaofcombininganddetection,thethesiscon-sidersthreedifferentstructureswithdifferentpropertiesandabilities.Theperformanceofaso-calledswitchingBPSKdetectorisanalyzedonanadditivewhiteGaussiannoise(AWGN)channel.Thisdetector,whichpermitsnoncoherentdemodulation,isshowntobeatleast2.5dBworsethanthedifferentialBPSKdetectoratabiterrorprobabilityof10-3;however,itsusecanstillbemotivatedincaseswhereonlyextremelylowcomplex-ityisallowed.Furthermore,aschemeforminimalinformation-destroyingword-widthreductionbeforedifferentialdetectionisproposedandanalyzed.Inadditiontotheaboveexperimentallytestedstructures,adecision-directed,Kalmanphase-andfrequencyesti-matorbasedcoherentcombinerisproposed.ItisdesignedforlownormalizedDopplerfading,multibranchchannelswithcarrierfrequencyoffsets.Areceiveremployingthisstructuretogetherwithapostdetectiondifferentialdecoderisshown,withsimulations,tooutperformadifferentialcombineronatime-invariant,3-branchAWGNchannel.Thesecondmaincontributionofthethesisistheanalysisofatimediscrete,noncoherentearly-late(NCEL)PNcodetrackingloop.Thesynchronizationblockisprecededbyadiscrete-timechip-matchedfilter(CMF)operatingatasamplingfrequencyequaltoamultipleλofthechipfrequency.AfterthederivationoftheNCELcodephasediscrimina-tor’sS-curve,alinearizedloopanalysisisdoneinordertodeterminethetotalloopgainfactorwithrespecttothedifferentpulse-shapesandoversamplingratiosλconsidered.Thestructure,withadifferentialBPSKdetectorappended,isanalyzedonanAWGNchannelwiththeaidofsimulations.Theresultsshowthatλisthemostcriticaldesignparameter;whencomparedtoideallysynchronizedD-BPSKdetection,theaverageper-formancedegradationsforthisstructurearearound0.1and0.3dBforλ=8andλ=2.5respectively.AcknowledgmentsIwouldliketobeginbyexpressingmygratitudetoProfessorHannuTenhunenforaccept-ingmeasaPhDstudentattheElectronicSystemDesignLaboratory.Ialsothankhimforprovidingacreativeatmosphereandforalwayshelpingoutonshortnotice.AhugethanksisalsosenttomycolleagueandfriendDanielKerekwhohastaughtmesomuch.NotmanyworkingcircuitswouldhavebeendesignedbytheradiogroupatESD-labwithouthisideas,instincts,broadknowledgeandthoroughwayofdoingthings.IamverygratefultoDr.WolfgangGranzow,notonlyforacceptingtobetheopponent/reviewerofthisthesis,butalsoforgivingmegreatcommentsandadvice.Here,IwouldalsoliketoacknowledgethedesignworkdonebyBengtOelmannonourthirdandlatestcircuit.ThanksalsotoDietrichHunoldfordoingagreatjobwhichresultedinafirst-rateMaster’sThesisofwhichasmallpartappearsinthiswork.TherestoftheESDcollectivenaturallydeservesrecognitionformakingupthisstimulat-ingenvironment.Withoutallyouguys,ESDlabwoulddefinitelybealessweirdplace,butohsoboring...TheconstantsupportfromthecomputersystemsgroupandAilaPohja’sneverrecedingenergyinstraighteningthingsout,arealsoacknowledged.“Thanks”toallthepeoplewhopatientlysitandlistentome,divergingintomyfieldofscience,afterthey’veaskedtheinnocentquestion“So,whatdoyoudoforaliving?”Notuntiltheend,whenIcometothephrase“it’sbasicallyabouttheelectronicsyouhaveinyourmobilephone,”dotheynodunderstandinglyandsayslightlyconfused“Butthat’salreadybeendone,hasn’tit?”FinallyI’dliketotaketheopportunitytosendamessage:ToKerstiandlittleX-youwillalwaysbemany,manytimesmoreimportantthanany140pagethesisalthoughthismightnothavebeencompletelyapparentduringthelastfewmonths.Kista,August1997HenrikOlsonContentsAbstractiAcknowledgmentsiiiContentsvNotationixAbbreviationsandAcronymsxiii1Introduction11.1Thesisbackground..............................................................................................................11.2Problemformulation...........................................................................................................11.3Designmethodologyoverview...........................................................................................21.4Projectframework..............................................................................................................31.4.1WalkstationII.....................................................................................................................31.4.2“Onechipradio”................................................................................................................31.4.3Thesisconstraints.................................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