Rapid-MIMO-OFDM-Software-Defined-Radio外文文献及外文翻译

外文文献原文24外文文献原文：RapidMIMO-OFDMSoftwareDefinedRadioSystemPrototypingAmitGupta,AntonioForenza,andRobertW.HeathJr.WirelessNetworkingandCommunicationsGroupDepartmentofElectricalandComputerEngineering,TheUniversityofTexasatAustin1UniversityStationC0803,Austin,TX78712-0240USAPhone:[phone],Fax:[phone]{agupta,forenza,rheath}@ece.utexas.eduAbstract—Multipleinput-multipleoutput(MIMO)isanattractivetechnologyforfuturewirelesssystems.MIMOcommunication,enabledbytheuseofmultipletransmitandmultiplereceiveantennas,isknownforitshighspectralefficiencyaswellasitsrobustnessagainstfadingandinterference.CombiningMIMOwithorthogonalfrequencydivisionmultiplexing(OFDM),itispossibletosignificantlyreducereceivercomplexityasOFDMgreatlysimplifiesequalizationatthereceiver.MIMO-OFDMiscurrentlybeingconsideredforanumberofdevelopingwirelessstandards;consequently,thestudyofMIMO-OFDMinrealisticenvironmentsisofgreatimportance.ThispaperdescribesanapproachforprototypingaMIMO-OFDMsystemusingaflexiblesoftwaredefinedradio(SDR)systemarchitectureinconjunctionwithcommerciallyavailablehardware.Anemphasisonsoftwarepermitsafocusonalgorithmandsystemdesignissuesratherthanimplementationandhardwareconfiguration.Thepenaltyofthisflexibility,however,isthattheeaseofusecomesattheexpenseofoverallthroughput.Toillustratethebenefitsoftheproposedarchitecture,applicationstoMIMO-OFDMsystemprototypingandpreliminaryMIMOchannelmeasurementsarepresented.Adetaileddescriptionofthehardwareisprovidedalongwithdownloadablesoftwaretoreproducethesystem.I.INTRODUCTIONMultiple-inputmultiple-output(MIMO)wirelesssystemsusemultipletransmitandmultiplereceiveantennastoincreasecapacityandproviderobustnesstofading[1].Toobtainthesebenefitsinbroadbandchannelswithextensivefrequencyselectivity,MIMOcommunicationlinksrequirecomplexspacetimeequalizers.ThecomplexityofMIMOsystemscanbereduced,however,throughorthogonalfrequencydivisionmultiplexing(OFDM).OFDMisanattractivedigitalmodulationtechniquethatpermitsgreatlysimplifiedequalizationatthereceiver.WithOFDM,themodulatedsignaliseffectivelytransmittedinparalleloverNorthogonalfrequencytones.ThisconvertsawidebandfrequencyselectivechannelintoNnarrowbandflatfadingchannels.CurrentlyOFDMisusedinmanywirelessdigitalcommunicationsystems,suchastheIEEE802.11a/g[2],[3]standardsforwirelesslocalareanetworks(WLANs).MIMO-OFDMtechnologyisintheprocessofbeingstandardizedbytheIEEETechnicalGroup802.11n[4]andpromisestobeastrongcandidateforfourthgeneration(4G)wirelesscommunicationsystems[5].外文文献原文25AsthetheorybehindMIMO-OFDMcommunicationcontinuestogrow,itbecomesincreasinglyimportanttodevelopprototypeswhichcanevaluatethesetheoriesinrealworldchannelconditions.Duringthepastfewyears,anumberofMIMO-OFDMprototypeshavebeendeveloped[6]–[12].TheseimplementationsmakeuseofFPGAsorDSPs,whichrequirealargeamountoflowlevelprogrammingandafixedpointimplementation.Thisisthepreferredsolutionwhendevelopinghigh-speedimplementations;however,ithinderstheflexibilityoftheplatformasthesesystemsarenoteasilyreconfigurable.Asaresultwhenexperimentingwithmanydifferentspace-timecodingschemesorreceiverdesigns,amoreflexiblesolutionmaybepreferred.InthispaperweproposeaMIMO-OFDMsystemarchitecturebasedonthesoftwaredefinedradio(SDR)paradigm.Theadvantageofthisapproachliesinthefactthattheuserisnotrequiredtohaveindepthhardwareknowledgeandmayimplementanumberofdifferentschemesbysimplyreconfiguringthesoftware.TheplatformusesNationalInstrumentsradiofrequency(RF)hardwareinconjunctionwiththeLabVIEWgraphicalprogramminglanguage.Withthisarchitecture,itispossibletodefineandsimulateasysteminahighlevelprogramminglanguageandthenseamlesslyapplythatcodetowardsthehardwareimplementation–thisgreatlyreducesthetimeinvolvedinsystemprototyping.Comparedwith[6]–[12],ourprototypingplatformcaneasilybereduplicatedasitconsistsofcommercial-off-the-shelfhardwareandpubliclyavailablesoftware.AuserwhopurchasestheRFhardwarefromNationalInstrumentsanddownloadstheavailableMIMOsoftwaretoolkitalongwiththeprototypingcodedevelopedbytheauthors(availableat[13],[14])canrealizethesamerapidprototypingbenefitswhichwediscussinthispaper.Theflexibilityofthecurrentimplementationoftheprototypeislimitedbysomehardwareconstraints,suchasthebandwidthofthePCIbus,whichpreventsfullyreal-timetransmissionoverthewirelesslink,andsoftwareconstraintslikeourlackofcompletesynchronizationalgorithmsinthesoftware,whichcausesustouseawiredsynchronizationchannel.ThespiritofthiscontributionistosummarizeourmethodanddescribeourfirsteffortstowardsthedevelopmentofacompleteMIMO-OFDMplatformdesignedforsystemvalidationandFig.1.A2×2MIMO-OFDMspatialmultiplexingsystemchannelmeasurements.Moreworkneedstobeinvestigatedtoovercomethelimitationsandexpandthecapabilitiesofourinitialdesign.Thispaperisorganizedasfollows.SectionIIexploresthesignalmodelforaMIMO-OFDMsystemandourspecificMIMO-OFDMimplementation.SectionIIIdiscussesthespecificsofthehardwareandsoftwareplatform.SectionIVshowspreliminaryresultsfromoursystemimplementationaswellaschannelmeasurementsinindoorenvironments.SpatialMultiplexingOFDMmo