可编程数字信号处理器在移动通信中的应用（TheApplicationofProgrammableDSPsinMobileCommunication）摘要：本书聚焦可编程DSP在移动通信中的工程应用，系统阐述2G/3G移动终端与基站的DSP实现方案。全书围绕DSP架构演进、低功耗设计、指令集优化及电源管理展开，详解双模终端架构、软硬件划分、协处理器设计与接触定义。同时覆盖天线阵列处理、MIMO信号提取、软件无线电挑战、多媒体应用、Java虚拟机适配、生物识别与安全机制等关键技术，结合OMAP平台、C55x系列处理器与典型案例，提供从算法、架构到工程实现的完整方法，为移动通信终端的低功耗、高性能DSP开发提供权威参考。TheApplicationofProgrammableDSPsinMobileCommunicationsEditedbyAlanGathererandEdgarAuslanderBothofTexasInstrumentsInc.,USACopyrightq2002byJohnWiley&Sons,LtdBaffinsLane,Chichester,WestSussex,PO191UD,EnglandNational01243779777International(+44)1243779777e-mail(forordersandcustomerserviceenquiries):cs-books@wiley.co.ukVisitourHomePageonhttp://www.wiley.co.ukorhttp://www.wiley.comAllRightsReserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmitted,inanyformorbyanymeans,electronic,mechanical,photocopying,recording,scanningorotherwise,exceptunderthetermsoftheCopyrightDesignsandPatentsAct1988orunderthetermsofalicenceissuedbytheCopyrightLicensingAgency,90TottenhamCourtRoad,London,W1P9HE,UK,withoutthepermissioninwritingofthePublisher,withtheexceptionofanymaterialsuppliedspeci-ficallyforthepurposeofbeingenteredandexecutedonacomputersystem,forexclusiveusebythepurchaserofthepublication.Neithertheauthor(s)norJohnWiley&SonsLtdacceptanyresponsibilityorliabilityforlossordamageoccasionedtoanypersonorpropertythroughusingthematerial,instructions,methodsorideascontainedherein,oractingorrefrainingfromactingasaresultofsuchuse.Theauthor(s)andPublisherexpresslydisclaimallimpliedwarranties,includingmerchantabilityoffitnessforanyparticularpurpose.Designationsusedbycompaniestodistinguishtheirproductsareoftenclaimedastrademarks.InallinstanceswhereJohnWiley&Sonsisawareofaclaim,theproductnamesappearininitialcapitalorcapitalletters.Readers,however,shouldcontacttheappropriatecompaniesformorecompleteinforma-tionregardingtrademarksandregistration.OtherWileyEditorialOfficesJohnWiley&Sons,Inc.,605ThirdAvenue,NewYork,NY10158-0012,USAWILEY-VCHVerlagGmbHPappelallee3,D-69469Weinheim,GermanyJohnWiley&SonsAustraliaLtd,33ParkRoad,Milton,Queensland4064,AustraliaJohnWiley&Sons(Canada)Ltd,22WorcesterRoadRexdale,Ontario,M9W1L1,CanadaJohnWiley&Sons(Asia)PteLtd,2ClementiLoop#02-01,JinXingDistripark,Singapore129809BritishLibraryCataloguinginPublicationDataAcataloguerecordforthisbookisavailablefromtheBritishLibraryISBN0471486434TypesetinTimesbyDeerparkPublishingServicesLtd,Shannon,Ireland.PrintedandboundinGreatBritainbyT.J.InternationalLtd,Padstow,Cornwall.Thisbookisprintedonacid-freepaperresponsiblymanufacturedfromsustainableforestry,inwhichatleasttwotreesareplantedforeachoneusedforpaperproduction.BiographiesAlanGathererreceivedhisBEngdegreeinElectronicandMicroprocessorEngineeringfromStrathclydeUniversity(Scotland)in1988.HethenmovedtoStanfordUniversityandobtainedMSandPhDdegrees,bothinElectricalEngineeringin1989and1993.HejoinedTexasInstrumentsin1993.Since1993,Dr.Gathererhasworkedondigitalcommunicationsresearchanddevelopmentintheareasofdigitalsubscriberline,cablemodemandwireless.Presentlyheisadistinguishedmemberoftechnicalstaffandmanagerofsystemsdevelop-mentwithinWirelessInfrastructureatTexasInstrumentswhereheleadsateaminvolvedinthedevelopmentoftechnologyforthirdgenerationcellulartelephony.Hepresentlyholds11patentsinthefieldofdigitalcommunications.EdgarAuslanderistheWorldwideStrategicMarketingDirectoratTexasInstrumentsWirelessCommunicationsBusinessUnit,Dallas,Texas,workingforthegeneralmanagerofthebusinessunitandTexasInstruments’seniorvice-president.SomeofthestrategicplanshehaswrittenhaveresultedinTexasInstrumentsacquiringorinvestingincompanies.HefirstworkedatTexasInstrumentsinNice,France,asEuropeanproductmarketingmanagerfortheTMS320digitalsignalprocessorsproductlinein1990.Mr.AuslanderbecameTexasInstruments’WorldwideGSMmarketingmanagerin1993priortohiscurrentposition.HeobtainedhisMEEngandMBAdegreesfromCornellUniversityandColumbiaBusinessSchoolin1988and1990,respectively.WhileatCornell,heheldseveralteachingassistantpositionsinsignalprocessinganddigitalcommunicationscourses.WhileatColumbiaBusi-nessSchool,hewasateachingassistantinstatisticsandworkedattheOfficeofScienceandTechnologyDevelopment,sellingColumbiaTelecommunicationsResearchCenter’spatentsrights.1IntroductionEdgarAuslanderandAlanGathererThisbookisabouttwotechnologiesthathavehad,andwillincreasinglyhave,asignificantimpactonthewaywealllive,learnandplay:personalwirelesscommunicationsandsignalprocessing.Whenitcomestobothmarkets,historyhasshownthatrealityhasoftensurprisedthemostoptimisticforecasters.WedrawontheexperienceofexpertsfromMIT,Berkeley,UCLA,WorcesterPolytechnicInstitute,INRIA,Authentec,Radioscape,GeovectorandTexasInstruments,togiveadescriptionofsomeoftheimportantbuildingblocksandimplementationchoicesthatcombinebothtechnologies,inthepastandinthefuture.Wehighlightdifferentperspectives,especiallyregardingimplementationissues,intheprocessingofspeech,audio,video,futuremultimediaandlocation-basedservicesaswellasmobilecommerceandsecurityaspects.Thebookisroughlydividedintothreesections:†Chaptersdescribingapplicationsandtheirimplementationsonwhatmightbedescribedas‘‘today’s’’technology.Bythis,wemeantheuseofprogrammableDigitalSignalProces-sors(DSPs)andASICsinthemannerinwhichtheyarebeingusedfortoday’sdesigns.Inthesechapters,wehighlighttheapplicationsandtheroleofprogrammableDSPsintheimplementation.†Chaptersthatpresentchallengestothecurrentdesignflow,describingnewwaysofachievingthedesireddegreeofflexibilityinadesignbymeansotherthanprogrammableDSPs.WhetherthesenewapproacheswillunseattheprogrammableDSPfromitsperchremainstobeseen,asthecommercialvalueoftheseapproachesislesscertain.ButtheygiveadetailedoverviewofthedirectionsresearchersaretakingtoleapbeyondtheperformancecurveoftheprogrammableDSPapproach.†Weconcludewithapracticalyetinnovativeapplicationexample,apossibleflavoroftheexcitingnewpersonalcommunicationsservicesenabledbydigitalsignalprocessing.Inthisintroduction,weoverviewtheaspectsofmobilecommunicationsthatmakeitauniquetechnology.Wedescribehowtheapplicationsassociatedwithmobilecommunica-tionshaveevolvedfromthesimplephonecallintoaslewofpersonaltechnologies.Thesetechnologies,andtheirimplementation,aredescribedinmoredetailinthesubsequentchap-ters.1.1It’saPersonalMatterThesocialimpactsandbenefitsofpersonalwirelesscommunicationsarealreadyvisible.Whenphoneswerenotportableandusedtoonlysitonadeskathomeoratwork,peoplewouldcallplaces:workorhome;butwhenphonesbecameportableandaccessibleanywhere,peoplebegantocallpeopleratherthanplaces:today,whenwecallpeopleweevenoftenstartbyasking‘‘Hello,whereareyou?’’.Themobilephonehasbecomeasafetytool:‘‘IwillbringthephonewithmeincaseIneedtocallforanemergency,ifanxiousfamilymemberswanttoreachme,orifIamlost’’.Themobilephonehasbecomeasocialtool,enablingmorefiexiblepersonallifeplanning:‘‘IdonotknowwhereIwillbeat2p.m.andwhereyouwillbe,butIwillcallyouonyourmobileandwewillsync’’.Arecentsurveyhasshownthatwhenpeopleforgettheirmobilephoneathome,avastmajorityiswillingtogobackhometogetit,evenwhenitimpliesa30-minutedrive.Themobilephonehasbecomeapersonalitemyoucarrywithyoulikeyourwallet,yourdrivers’license,yourkeys,orevenwear,likeawatch,apen,orglasses:itmadeittothelistofthefewitemsthatyoucarrywithyou.Ifyouareateenager,agamingdeviceoranMP3playeralsomadetheirroominyourpocket,andifyouareabusyexecutiveapersonalorganizerismaybemorelikelytohavethisprivilege.Figure1.1illustratestheintegrationofnewfeaturestrend;conversely,thewirelesscommunicationtechnologywillbepervasiveindifferentend-equipmentsandcreatenewmarketsforwirelessmodulesembeddedincarsforexample.Tosome,theuseofamobilephoneinpublicplacesisanannoyance.Peerpressure‘‘dictates’’youhaveamobilephonetobereachable‘‘anywhereanytime’’;nothavingamobilephonebecomesanti-socialinScandinaviancountriesforexample,wherepenetrationishigherthan70%ofthewholepopulation.Likeforeverydisruptivetechnologywidelyused,anewetiquettehastobeunderstoodandagreedupon,e.g.phoneshavetobeturnedofforputinsilentmodeatconcertsorinrestaurants.Phonesarenowprogrammedwithdifferentringingprofilesthatare‘‘environmentfriendly’’(e.g.meetingmoderingsonlyonceandmakesthephonevibrate).Inthefuture,wemightseephonesthatareenvironmentaware,withsensorsthatdetectifthephoneisinabagandneedstoringlouderforexample.Inthepast,Matra-AEG,nowNokiaMobilePhones,introducedaGSMphonethathadaninfra-redsensorthatservedasaproximitydetectorsoastoputthephoneautomaticallyonoroffhands-freemode.Ringingprofileshavealsootherniceapplications:pairedwithCallerID,theyenableuserstohavedifferentringingtonesfordifferentcallers(friends,family,businesspartners,unknown…).1.2TheSuperPhone?Tothevastmajority,themobilephoneistheultimatetelecommunicationtool,viavoiceorshortmessages,soontobecomemultimediamessagesormultimediacommunications.Forsome,itisaforegoneconclusionthatwirelessterminalswillcontinuetheirmutationfromfairlysimple,voice-orienteddevicestosmarterandsmartersystemscapableofincreasinglymorecomplexvoiceanddataapplications.TheargumentgoesthatwirelessphoneswilltakeonthecapabilitiesofPersonalDigitalAssistants(PDAs)andPDAswillsubsumemanyofthevoicecommunicationscapabilitiesofmobilephones.Thislineofreasoningproclaimsthatthehandsetsofthefutureeventuallywillbecomesomesortofsuper-phone/handheldcomputer/PDA.Butintheend,themarketplaceisnevernearlyasneatandtidyasonemightimagine.Ratherthananinexorablequestforaone-size-fits-allsuper-phone,thefractiousforcesofthemarket,basedastheyareoncompletelyillogicalhumanemotions,nodoubtwillleadhandsetmanufacturersdownanumberofavenuesinsupportof2.5Gand3Gapplications(2.5and3Grefertocomingphonestandardgenera-tionstobedescribedlaterinthisbook).Manymobilehandsetswillbecapableofconvergedvoice/dataapplications,butmanywillnot.Instead,theywillfulfillaperceivedconsumerneedorperformacertainspecializedfunctionverywell.Ratherthanahomogenousmarketofconvergedsuper-phones,theterminaldevicesfornextgenerationapplicationswillbeasdiverseastheyaretoday,ifnotmoreso.Andtheywillbeasdiverseastheapplicationsthatwillmakeupthe2.5Gand3Gmarketplace.MobiledeviceOEMsmustbepreparedtomeetthechallengeofadiverseandsegmentedmarket.Figure1.2illustrateshowwirelessphoneservicestartedtobeaffordabletoafewprivilegedbusinessprofessionalsandhowitdiversifiedintimetobecomeaconsumeritem.Thehigh-endphoneoftodayistheclassicphoneoftomorrowasfashionandtechnologyevolveandaspeoplebecomeusedtoinno-vationsbroughttothem.Webelievethattheincreasingneedforfunctiondiversificationwilldrivetheprogram-mableDSPintoanevenmoreintegratedrolewithinthemobiledevicesoftomorrow.Non-programmableDSParchitectureswillhavetotakeonmanytraitsoftheprogrammableDSPinordertocompetewithit.ThelaterchaptersofthisbookhighlightthatthefutureofprogrammableDSPsinmobileapplicationshingesontheirabilitytobringtherightlevelofflexibility,alongwithlowpowerperformance.Overthelastseveralyears,themarketforterminalsfirstbecamepolarizedandthenstratified.Themarketfirstpolarizedatthehighandlowendsofthespectrum.Asmorefeaturesandfunctionscouldbeaddedtohandsets,theywereandthismadeupthehighend.Buttoattractnewsubscribers,wirelesscarriersstillwantedlow-end,low-costyetrobustmobilephones.Infact,fortheserviceproviderofferingfreehandsetstoeachnewsubscriber,thelowerthecostofthehandset,thebetterofftheserviceproviderwouldbe.Inthelastfewyearsthough,themarkethasshownthatitwillsplinterandstratifywithseveraldifferentlayersormarketsegmentsbetweenthepoles.Someofthedistinctsegmentsthatareemergingcanbedefinedas:†Data-centricdevices:evolvingfromthePDA,theseadvancedpalmtopcomputerswillbeintegratedwithcellularvoiceandretainorevenexpandupontheircomputingcapabilities.Data-centricdevicescanalsobemodemcards(nokeyboard,nodisplay!)thatcanbepluggedintolaptops.†Smart-phones:migratingfromthecellulartelephonesegmentoftoday’smarket,smart-phoneswillperformtheirvoicecommunicationsfunctionsquiteeffectively,buttheyalsowillbeequippedwithlargerdisplayscreenssotheycanbegintoperformnewapplicationslikee-mailaccess,Internetbrowsingandothers.†Fashionphones:thesedeviceswillusefashiontechniquestoappealtoseveralsegmentsofconsumers.Thebusinessperson,forexample,willbeattractedtoacertainlookandfeeltomakeafashionstatement.Youngerconsumerswillhavequitedifferenttastes.Althoughtheywillcrossseveraldemographicmarketsegments,thesetypesofphoneswillappealtobuyerswhoarefashion-consciousandwhowillusefashiontomakeastatementabouttheirlifestyles.†Classicmobilephones:foruserswhoarelookingforaworkhorsemobilephone,theclassichandsetwillbesmallandeasy-to-handle,anditwillperformeffectivelythemostfrequentlyusedcommunicationsfeatures.†Low-endphones:serviceproviderswillcontinuetoofferfreephoneswithservicecontracts.Thesesmall,lightandrobustphoneswillremainamainstayinthemarketbecausetheyperformaveryvaluablefunction.Theyoftencomewithapre-paidcallingplanbundle.Theyattractfirst-timeusers.Inthefuture,wemightseesuchphoneswithoutakeyboardoradisplay(tosavecost):phonecallswouldbemadeviaanoperatorsittinginacallcenteroravoicedialing/recognitionsystem,mostlikelyinthenetwork.†Bluetooth-enabledphones:Bluetoothisashortrange,low-cost,lowpowerwirelesstech-nologyoperatinginthe2.4GHzunlicensedband.Bluetooth-enabledphonescanbeanyoftheabovecategories,buttheformfactorsmaychangedramaticallyasthephonewillnowbedistributedaroundyourbody.ThetypesofhandsetsthatcanbeidentifiedareillustratedinFigure1.3(conceptphonescourtesyofNokia).Whatisnotknowniswhattomorrowmayholdandtheeffectsnewapplicationswillhaveonthesize,shapeandfunctionoffutureterminaldevices.Onethingisforcertain:newtechnologieswillbedevelopedthatwillaltertheformfactorsinusetoday.Forexample,aBluetooth-enabledphonemaybeabelt-attachedcontroller/gatewaydevicelinkedtoanearpiecethatcommunicatesaudioinformation.Adisplayunitofsomesortcouldbeconnectedtotheuser’seyeglassesforcommunicatingvisualdata.Andbeyondthesefairlynewapplications,medicalsensorscouldbedeployedtomoni-tortheperson’sheartbeatorothervitalfunctions.Asmallbox,comparabletoafiatpagerinsize,willincorporatecellularandBluetooth(oranothertechnologysuchasIEEE802.11BorIEEE802.15)functionalitiescombined,tocommunicatewithacollectionoffashionableaccessories;theaccessories,ofthesizeandweightofapen,orafiatscreenforexample,willformapersonalareanetworkofthinclientscommunicatingviaBluetoothwiththesmallbox,thePersonalMobileGateway(Figure1.4,courtesyofIXIMobileInc.).Thatwaythe‘‘all-in-one’’terminal,oftentoobigtobeaphoneandtoosmalltobeaPDA,willbecomeacollectionofsmartyetthin,fashionableandlowcostdevices.Theconceptwouldappealtobothmobileprofessionalsandteenagers,theprimarytargetfortheeverincreasingreplacementmarket.1.3NewServicesWehavediscussedwirelessdevices,butwhatusersreallycareaboutaretheservicesthosedeviceswillbringtothem,andindustryplayerscareabouthowmoneywillbemade.Beforedescribingthenewservicesthatarelikelytobeofferedthankstopersonalmobileterminals,alittlehistorylessonwillbeusefulandremindustobehumble,especiallywhenitcomestopredictingthefuture!Whenthetelephonewasinvented,itwasoriginallytoimprovethetelegraphsystem.ThefundamentalideaoftheelectricaltransmittingofsoundwaspublishedbyCharlesBourseulfirstin1854inthemagazineL’IllustrationdeParis.AlexanderGrahamBellpatentedhistelephoneonthe14February1876,just3hoursbeforeElishaGray.Nobodywasinterestedinhisinventionfirst.WhenheaskedtheWesternTelegraphCompanyin1877tobuyhispatentfor$100,000,theresponsewas‘‘Whatshallwedowithatoylikethat?’’.Therewassomedoubtastotheusetowhichtelephonesmightactuallybeputinpractice.Demonstrationsoftenincludedspeech,songandmusic,anditwasnotuncommonforthemusicaldemonstrationstobetechnicallythemostsuccessful.‘‘Themusicaltelephone’’wasamajorattractionattheInternationalElectricalExhibitioninParisin1881,wheretheFrenchengineerClementAderdemonstratedstereophonictransmissionbytelephonedirectfromthestagesoftheParisOperaHouseandtheCome,dieFranaise.Itwasbelievedtobethemajorapplicationoftelephony.In1890,acommercialcompany,CompagnieduTheatro-phone(Figure1.5),wasestablishedinParis,distributingmusicbytelephonefromvarioustheatrestospecialcoin-operatedtelephonesinstalledinhotels,cafes,etc.andtodomesticsubscribers.Theservicecontinueduntil1932,whenitwasmadeobsoletebyradiobroad-casting.Thephonehascomealongwaysincethen,andthefirstmassmarketapplicationissimply…talkingwithotherpeople.WiththeadventoftheInternetandwirelessdataservices,anewrealmofpossibilitiesarealreadyoffered,thatgofarbeyond‘‘justtalkingwithotherpeople’’,aswitnessedbytherecentsuccessofNTTDoCoMo’sI-modeserviceinJapan.Servicecategoriesofthenearfuturewillencompasspersonalizedinformationdeliveryfornews,location-dependantservices,travel,bankingandpersonalhobbies;itwillalsoincludeproductivity-relatedservicessuchasVirtualPrivateNetwork(VPN)withtheofficeorthefamily,personalassistant,agendas,andaddressbooks;extendedcommunication,includinge-mail,postcardtransmission,andofcourseentertainment.Nokiahasalreadyintroducedphoneswithgamessuchas‘‘thesnake’’,butthefuturewillbringmuchmoreexcitinggames(on-lineaswellasoff-line,puzzles,gambling)andnewformsofentertainment:music(ringtones,clipsandsongs),TV(schedules,clips),chatgroups,astrology,datingservicesandwhatissometimescalled’’adultentertainment’’.Figure1.6showssomeoftheservicecategories.Thesuccessfuldeploymentoftheserviceswilldependoneaseofuse,convenience,pertinence,andclearaffordablebilling.Thepertinenceoftheservicewillrequirepersona-lization;profilingtechnologycanbeusedtomatchcontenttotheneedsoftheusers.Loca-tion-basedserviceswillenableorfacilitatesuchprofiling.Ofcourselocalizationwillhavetobevolunteeredand‘‘legally-correct’’information.Mostmobilelocation-basedservicestodayusepositioningbasedonCellofOrigin(COO),buttheprecisionisoftenmediocre,linkedtocellsize;insomecases,thisisacceptableenough.Anothermethod,knownasEnhancedObservedTimeofDifference(EOTD)isusedinsomeGSMnetworks.TimeofarrivalsignalsfrombasestationsaremeasuredbythephoneandwhatiscalledaLocation-MeasurementUnit(LMU).InfutureUMTSsystems,asimilartechniquewillbeusedthatisknownasObservedTimeDifferenceofArrival(OTDOA).ThelocationmethodswejusttalkedaboutonlyusethenetworkandLMUsasameanstogetlocationinformation;theuseofGlobalPositioningSystem(GPS)givesbetterresults,butthecostofaGPSreceiverhastobeaddedtothephone.Anillustrationofaninnovativewaytoexploitandpresentlocation-basedservicesisgiveninthelastchapterofthebook.1.4TheCurseandOpportunityofMoore’sLawMoore’slawpredictedtherapidincreaseintransistordensityonsiliconchips.Alongwiththisincreaseintransistordensity,cameanincreaseinclockspeed,chipsize,andcomponentdensityonboards.Allthishasgiventhesystemdesigneranexponentiallyincreasingamountofprocessingpowertoplaywithinhisorherquestformoreandmoresophisticatedsystems.Thedesigncommunityhasreactedtothisexplosionbymakinglessandlessefficientuseofthetransistorsofferedtoit.Thishasbeentruesincewefirstmovedfromhandlaidouttransistorstologicgates.Thelatterislessefficientintermsofsiliconareaandspeedoptimization,butismuchmoreefficientintermsofamorepreciousresource:humanintel-lect.FromlogictoRTLtomicroprocessors,thedesignerhasmovedtoanincreasinglyhighlevelofabstractioninordertodesignmoreandmorecomplexdevicesinreasonabletime-frames.Despitethis,designerscontinuetolagbehindprocessengineersintheirabilitytoconsumethetransistorsbeingmadeavailabletothem.ThiscanbeclearlyseeninFigure1.7whichplotstheabilityofadesignertousetransistorsagainsttheavailabilityoftransistorsthatcanbeused.Thistrendmakestheuseofprogrammabledeviceswithinmobilecommu-nicationssystemsinevitablefortheforeseeablefuture.Theonlyquestionis,whatwilltheseprogrammabledeviceslooklike?ProgrammableDSPsareprogrammabledevicesthatincludefeaturesthatenableefficientimplementationofsystemswithinthespecialclassofsignalprocessingproblems.ByfocusingonsignalprocessingDSPdesignershaveputprogrammableDSPsattheheartofmanyconsumerdevices,includingmobilecommunicationsystems.RecentlyDSPshavebeenspecializedtoperformspecificallyinthedomainofsignalprocessingformobilecommunications(moredetailsaregiveninChapter2).ThebalancebetweenspecializationandflexibilityisimportantforanyDSPtosucceed.AsDSPsareprogrammable,theyarenot‘‘justpiecesofsilicon,’’theycomewithadevelopmentenvironment.Intheearly1980s,DSPwasconsideredblackmagic,usedbyguruswhowroteallapplicationsinassemblylanguage.Now,powerfuldevelopmenttoolsincludingapplicationboards,emulators,simulators,debuggers,optimizingHighLevelLanguage(HLL)compilers,assemblers,linkers,blockdiagramenvironments,codegenerators,real-timeoperatingsystems(enablingeasiermultitasking,preemptivescheduling,highspeedcontextswitching,lowinterruptlatency,andfast,flexibleintertaskcommunication)aswellasmanyDSP-relatedbooksandapplicationnotesandinnovativevisualtoolshavemadeDSPtechnologyatoolforrapiddesignofincreasinglycomplexsystems.IncompetitiontoDSPs,‘‘siliconcompilers’’havearisen.Thesecompilerspromisetotakehighleveldescriptionsofasystem,andoutputadesignreadyforsynthesis,usuallywithacertainamountofuserfeedbackalongtheway.Thoughsuchtoolshaveshownsomesuccessandarenodoubtausefultoolinadesignersarsenal,theydonotprovideawaytomodifyasystemonceithasbeenfabricated.Thisisbecominganincreasinglyimportantrequirementbecausesystemsevolvequicklyandareincreasinglydifficulttospecifyatdesigntime.Forinstance,amobilehandsetmaynotbefullytesteduntilithasbeenusedinthefield.Theincreasingcostofmasksetsforthefabricationofchipsmeansanychangethatcannotbedonebyreprogrammingmaycostmillionsofdollarsandmonthsoftime.Thisisunacceptableintoday’smarketplace.更多内容见附件免责声明：本页面/内容部分素材来源于互联网公开信息，旨在传递更多信息，不代表本平台立场。版权归原作者或机构所有，如涉及侵权，请通过平台联系我们，我们将在核实后第一时间处理。本平台对转载内容的真实性、准确性不作任何保证，用户需自行判断并承担使用风险。
优化后铺层结果
