协同通信和AF和DF中继协议样本.docx

协同通信和AF和DF中继协议样本.docx

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协同通信和AF和DF中继协议样本

协同通信和AF和DF中继协议样本

协同通信和FAF和和FDF中继协议本文档所提供的信息仅供参考之用，不能作为科学依据，请勿模仿。

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AbstractNowadays,thereisatrendformunicationsystemthatthewholeworksystemisbeingdynamicsothattherearealwayshavingdevicesshouldbeembeddedandremoved.Conventionalwiredmunication,duetotheplexityofcabling,doesnotadapttothemodernmunicationsystem.Wirelesstechniquehasbeenusedwidelybecausedevicescanbeconnectedbyelectromagismwavewithoutcabling.However,lowtransmittingreliablitybecauseofinter--interferencebetweenelectromagismwavesisthekeyproblemofwirelessmunication.Basedonthis,thisthesisinvestigatesoneofthetechniquecalledcooperativemunicationanditcooperativeprotocols.Cooperativemunicationisavirtualmultiple--inputmultiple--output（MIMO）system.Toincreasethereliabilityofsignaltransmittedwithoutincreasingtheamountofmunicationdevices,thistechnologytriestomakeeachantennashaveoneormorepartnersthatassistthemtotransmitthesignal.Inwirelesswork,thedevicesnotonlytransmittheirownsignalbutalsoassisttheir“partner”totransmittheirsignalforsavingthecostofinstallationofadditionalantennasatbothreceiverandsenderInthisthesis,wefocusonintroducingthreemainprotocolsincooperativemunication:

Amplify--and–Forward（AF）,Decode--and--Forward（DF）andCodedCooperation（CC）.TheperformanceandmathematicalequationsofAFandDFareanalysed,andthenMATLABprogramswerecreatedtosimulatetheperformanceofthesetwoprotocols.Aboutthethreeprotocols,themainproceduresarealsointroduced.TheperformanceparisonforAFandDFindifferentsignal--to--noise（SNR）are本文档所提供的信息仅供参考之用，不能作为科学依据，请勿模仿。

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demonstrated.TheresultpresentsthattheDFprotocolshasbetterperformancethanAF.Finally,someremendationsandfutureworkarementionedattheendofthethesis.本文档所提供的信息仅供参考之用，不能作为科学依据，请勿模仿。

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ListofAbbreviationsandSymbolsMIMOMultipleinputmultipleoutputSISOSingleinputsingleoutputAFAmplify-and-ForwardDFDecode-and-ForwardCCCodedCooperationBERBiterrorrateQPSKQuadraturephase-shiftkeyingi.i.dindependentlyandidenticallydistributionMLMaximumlikelihoodSNRSignal–noise-ratio本文档所提供的信息仅供参考之用，不能作为科学依据，请勿模仿。

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1IntroductionBackgroundWirelessmunicationis,recently,thefastestimprovingsegmentandmostwidelyusedwayofthemunicationindustry.Forutilizingthebroadcastpropertyofelectromagismwave,theinformationcanbetransmittedinwirelessenvironment,whichsavesmuchcostforcablingandmakesthechangeofworkstructureeasily.Ontheotherhand,aswirelesstechniqueisusedmorewidely,therearealsomanyproblemsappearing.Forexample,thewirelesssignalcanbeaffectedalotbythetransmittingmediumandinterferedwithothersignalandthedestinationwillreceivenotonlythedirectwavebutalsosomeextrawaves.Thesesortsofwavesignalwillgenerateandformthereceivedsignalatthedestination,whichwillresultinsharplydifferingwiththeoriginalsignalsothatdecreasesthequalityofsignalandreliability.Thisiscalledmultipathfading[11].Tosolvetheseproblems,cooperativemunicationisoneofthemethods.CooperativemunicationtechniqueisamethodbasedonMIMO（multiple--inputmultiple--output）system.MIMOsystemisamodelthatinstallingmorethanoneantennasinboththesenderandreceiver,whichachieveonesignalistransmittedbydifferentchannels.Inpractical,duetothelimitationofsize,powerwasteandhardware,itishardtoinstallalotofantennasinonemunicationdevicesothatMIMOtechniqueishardtoutilizeinpracticaldirectly.Thus,cooperativemunicationisamodelthatbuildsavirtualMIMOsystemamongexistingantennasinsteadofbuildingadditionalantennasbutachievesthegainofMIMOsystem[8].本文档所提供的信息仅供参考之用，不能作为科学依据，请勿模仿。

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Comparedwithtraditionaltransmittingmethod,cooperativemunicationbuildsacooperativeworkrelationshipbetweeneachantennawhichmeanseachantennawillhaveahelpertoassistthemtotransmitsignalandthesehelperantennaswilltakesomemeasurestooptimizethequalityofsignal.Therefore,atthedestination,lotsofsignalswillbereceivedsothatreceivercanhavegainofdiversity.Someprotocolsdescribewhatfunctionsstheseantennasapplyforoptimizingsignal.Inthisreport,someexplanationsandliteraturereviewsfocusedonamplifyandforwardprotocol,decodedandforwardprotocolandcodedcooperativeprotocolaredemonstrated.Otherwise,simulationresultforamplifyandforwardanddecodedandforwardprotocolismade.ObjectivesThepurposeofthisprojectistoanalysetheadvantagesofcooperativemunicationbyanalysisofthreemaincooperativeprotocols.Inthishalfyear,thisprojectcanhaveaconclusionaboutthreeobjectives:

1.Tryingtounderstandtheconceptofcooperativemunicationanditsworkingsystemmodelss.Researchforhowthesignaldeliveredthroughnodes.2.FFindingthethreecooperativeprotocolsthatantennasobey—AF（amplify—and--forward）,DF（decode--and--forward）andCC（codedcooperation）protocolsandhowtheyworks.3.UsetheMATLABtosimulatetheperformanceofAFandDFanddoaparisonaboutthem.Approaches本文档所提供的信息仅供参考之用，不能作为科学依据，请勿模仿。

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Firstly,analyyzzingtheconceptofcooperativemunicationandfindingthefundamentalprotocolssaboutit.Secondly,findingtheimportantdescribedequationsandtheusedcoefficients.Finally,useMATLABtosimulatetheproceduresofAFandDFandtrytogettheBER（biterrorrate）--SNR（signal--Noiseratio）diagramandparethetheirperformance.ThesisoutlineThisreportincludesfiveparts:

firstpartintroducethebackgroundofcooperativemunication.Secondpartexplainssseveralliteraturereviewssaboutwireless,diversitytechnology,MIMOandcooperativeprotocols.ThirdandforthpartsdemonstratethesimulationaboutAFandDFandgettheresultdiagram.Additional,theforthpartalsoincludestheperformanceparisonbetweenAFandDF.Lastpartmakeessaconclusionandthefutureworkabouttheproject.本文档所提供的信息仅供参考之用，不能作为科学依据，请勿模仿。

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2LiteratureReviewOverviewTooverethelackofmultipleantennaslimitedbysizeorhardwareplexity,cooperativemunicationisproposed.Cooperativemunicationcanbeunderstoodavirtualmultipleinputmultipleoutput（MIMO）systembetweensourceanddestination.Inanotherwords,thecooperativemunicationbuildacooperativerelationshipamongexistingantennas.Forutilizingthebroadcastpropertyofelectromagismwave,notonlythedestination,therearealsosomeotherantennasreceivethesourcesignal.Insteadofdiscardingthissignal,thisrelationshipaskstheseantennastotakesomemeasurestoprocessthissignalandretransmitittotheappointeddestination.本文档所提供的信息仅供参考之用，不能作为科学依据，请勿模仿。

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FigurevirtualMIMOsystemTodecreasethebiterrorrateandrecoverthesourcesignalwell,therearethreemonprotocolsforthehelperantennasapplying:

amplifyandforward（AF）protocol,decodedandforward（DF）protocolandcodedcooperative（CC）protocol.本文档所提供的信息仅供参考之用，不能作为科学依据，请勿模仿。

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FigureCooperativemunicationSpatialdiversitytechnologyCooperativemunicationutilizesthespatialdiversitytechnology.Diversityisanideathattransmittingasignalthroughmanyindependentchannels,itisdescribedin[1].Whensourcesendsonesignalindifferentindependentchannels,thedestinationwillreceivemanyformatsaboutthissignal.Inthisway,itcanincreasethesignal--to--noiseratio（SNR）atthereceiverwhichresultinrecoveringthesourcesignalbetter.Therearethreemondiversitytechnologies:

timediversity,frequencydiversityandspatialdiversity.Spatialtechnologyistobuildmanyrelaystoretransmitthesignalwhichcreatesadditionalchannelsinspace.Thecooperativemunicationappliesthespatialdiversitytechnologymainly[4].BasicModelforWirelessSingleinputandsingleoutput（SISO）systemSingleinputandsingleoutputisthetraditionmodelwhichbothtransmitterandreceiverhaveoneantennatosendorreceivesignal.Inthisway,theinformationistransmittedbyelectromagismwaveintheair.Duetotheeffectofmultiplepathfading,thedestinationishardtorecoverthesourcesignalfromreceiversignal.Multipleinputandmultipleoutput（MIMO）systemAsthenamesaid,MIMOallowsboththesourceanddestinationtohavemultipleantennastosendandreceivesignal[9].Duetotheeffectof本文档所提供的信息仅供参考之用，不能作为科学依据，请勿模仿。

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multiplepathfading,thequalityofsignalwillbedecreased.However,bybuildingadditionalwaysbetweensourceanddestination,moreinformationwillbetransmittedatthesametimeandforthedestinationmanyformatsofsourcesignalwillbereceivedsothatMIMOcangreatlyimprovethespectrumutilizationandchannelcapacitywithoutincreasingthebandwidth.Butmoreantennasmeanmoremunicationdevicesinbothsourceanddestination.Ithastocostalottobuildenormoussystemtosupportthemultiplexingtechnology[9].FigureMIMOsystemCooperativemodelThebasiooperativemodelisthesource--relay--destinationmodel.Herewedefinedthecooperativeantennaasrelay.Thismodelisnaturallyrepresentedbythegraphbelow[3].Herewesetthesource--to--relaychannelgaintoH1,noiseisN1;thegainofsource--ttoo--destinationtoH2,noiseisN2;thegainofrelay--to--destinationtoH3,noiseisN3.Atthefirsttimeslot,thesourcesentthesourcesignalX1totherelayanddestination:

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Y2=H1*X1+N1Y3=H2*X1+N2Atthesecondtimeslot,therelaytakessomemeasurestoprocessthereceivedsignalY2,wesettheprocesstoC:

X2=C*Y2.Then,therelayretransmittedtheX2tothedestination:

Y4=H3*X2+N3.Asaresult,atthedestinationY4andY3arereceived:

Y3=H2*X1+N2Y4=C*H3*H1*X1+C*H3*N1+N2Thedestination’staskisrecoveringX1fromY3andY4.CooperativeschemesAlthoughthespatialdiversitytechnologycanincreasetherateofsuessfulpacketreceiptandthereceiverSNR,duringthesignaltransmittingthrou