协同通信与AF和DF中继协议文档格式.docx
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协同通信与AF和DF中继协议文档格式.docx
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1Introduction9
1.1Background9
1.2Objectives9
1.3Approaches9
1.4Thesisoutline10
2LiteratureReview12
2.1Overview12
2.2Spatialdiversitytechnology13
2.3BasicModelforWireless13
2.3.1SISOsystem13
2.3.2MIMOsystem14
2.3.3Cooperativemodel14
2.4Cooperativeschemes15
2.4.1Amplify-and-forwardmethod16
2.4.2Decode-and-forwardmethod16
2.4.3Codedcooperation17
3SimulationandAnalysesofAF21
3.1Overview21
3.2Maximumlikelihoodmethod21
3.3SimulationandAnalysis21
3.3.1Thewholeprocedureandanalysis21
3.3.2Simulation24
3.4Summary26
4SimulationandAnalysisofDF27
4.1Overview27
4.2Quantizationmethod27
4.3ConvolutionalCodeandViterbidecode27
4.3.1Convolutionalcode28
4.3.2Viterbidecode28
4.4Simulationandanalysis28
4.4.1Thewholeprocedureandanalysis29
4.4.2Simulation30
4.5PerformancecomparisonbetweenAFandDF31
4.6Mainchallenges32
4.7Summary33
5Conclusionsandfuturework34
5.1Conclusion34
5.2Prospect34
5.3Futurework35
36
37
Reference
AppendixAThesisspecification
AppendixBLogbookSummarySignature40
AppendixCMATLABprograms41
C.1Amplify-and-ForwardProtocol41
C.2Decode-and—Forwardprotocol42
C.3Rayleighchannel
4..5
ListofFigures
Figure2.1virtualMIMOsystem
Figure2.2Cooperativecommunication
Figure2.3MIMOsystem
Figure2.4Cooperativemodel
Figure2.5Relayamplifymodel
Figure2.6Decodedandforwardmodel
Figure2.7Codedcooperativemodel
Figure2.8Codedcooperationdataallocation
Figure2.9Fourcasesincodedcooperative
Figure3.1firsttimeslotinAFmethod
Figure3.2SecondtimeslotinAFmethod
Figure3.3AFprotocolBERdiagram:
:
…
Figure4.1(n,k,m)convolutionalencoder:
.:
.•.92
Figure4.2firsttimeslotofDF
Figure4.3Secondtimeslot
Figure4.4DFprotocolBERdiagram
Figure4.5DFwholeprocedures..
Figure4.6performaneecomparedbetweenAFandDF
ListofAbbreviationsandSymbols
MIMO
Multipleinputmultipleoutput
SISO
Singleinputsingleoutput
AF
Amplify-and-Forward
DF
Decode-and-Forward
CC
CodedCooperation
BER
Biterrorrate
QPSK
Quadraturephase-shiftkeying
i.i.d
independentlyandidenticallydistribution
ML
Maximumlikelihood
SNR
Signal-noise-ratio
1Introduction
1.1Background
Wirelesscommunicationis,recently,thefastestimprovingsegmentandmostwidelyusedwayofthecommunicationindustry.Forutilizingthebroadcastpropertyofelectromagnetismwave,theinformationcanbetransmittedinwirelessenvironment,whichsavesmuchcostforcablingandmakesthechangeofnetworkstructureeasily.Ontheotherhand,aswirelesstechniqueisusedmorewidely,therearealsomanyproblemsappearing.Forexample,thewirelesssignalcanbeaffectedalotbythetransmittingmediumandinterferedwithothersignalandthedestinationwillreceivenotonlythedirectwavebutalsosomeextrawaves.Thesesortsofwavesignalwillgenerateandformthereceivedsignalatthedestination,whichwillresultinsharplydifferingwiththeoriginalsignalsothatdecreasesthequalityofsignalandreliability.Thisiscalledmultipathfading[11].Tosolvetheseproblems,cooperativecommunicationisoneofthemethods.
CooperativecommunicationtechniqueisamethodbasedonMIMO(multiple-inputmultiple-output)system.MIMOsystemisamodelthatinstallingmorethanoneantennasinboththesenderandreceiver,whichachieveonesignalistransmittedbydifferentchannels.Inpractical,duetothelimitationofsize,powerwasteandhardware,itishardtoinstallalotofantennasinonecommunicationdevicesothatMIMOtechniqueishardtoutilizeinpracticaldirectly.Thus,cooperativecommunicationisamodelthatbuildsavirtualMIMOsystemamongexistingantennasinsteadofbuildingadditionalantennasbutachievesthegainofMIMOsystem[8].
Comparedwithtraditionaltransmittingmethod,cooperativecommunicationbuildsacooperativeworkrelationshipbetweeneachantennawhichmeanseachantennawillhaveahelpertoassistthemtotransmitsignalandthesehelperantennaswilltakesomemeasurestooptimizethequalityofsignal.Therefore,atthedestination,lotsofsignalswillbereceivedsothatreceivercanhavegainofdiversity.Someprotocolsdescribewhatfunctionstheseantennasapplyforoptimizingsignal.Inthisreport,someexplanationsandliteraturereviewsfocusedonamplifyandforwardprotocol,decodedandforwardprotocolandcodedcooperativeprotocolaredemonstrated.Otherwise,simulationresultforamplifyandforwardanddecodedandforwardprotocolismade.
1.2Objectives
Thepurposeofthisprojectistoanalysetheadvantagesofcooperativecommunicationbyanalysisofthreemaincooperativeprotocols.Inthishalfyear,thisprojectcanhaveaconclusionaboutthreeobjectives:
1.Tryingtounderstandtheconceptofcooperativecommunicationanditsworkingsystemmodels.Researchforhowthesignaldeliveredthroughnodes.
2.Findingthethreecooperativeprotocolsthatantennasobey—AF(amplify—and--forward),DF(decode-and-forward)andCC(codedcooperation)protocolsandhowtheyworks.
3.UsetheMATLABtosimulatetheperformanceofAFandDFanddoacomparisonaboutthem.
1.3Approaches
Firstly,analyzingtheconceptofcooperativecommunicationandfindingthefundamentalprotocolsaboutit.Secondly,findingtheimportantdescribedequationsandtheusedcoefficients.Finally,useMATLABtosimulatetheproceduresofAFandDFandtrytogettheBER(biterrorrate)-SNR(signal-Noiseratio)diagramandcomparethetheirperformance.
1.4Thesisoutline
Thisreportincludesfiveparts:
firstpartintroducethebackgroundofcooperativecommunication.Secondpartexplainsseveralliteraturereviewsaboutwireless,diversitytechnology,MIMOandcooperativeprotocols.ThirdandforthpartsdemonstratethesimulationaboutAFandDFandgettheresultdiagram.Additional,theforthpartalsoincludestheperformancecomparisonbetweenAFandDF.Lastpartmakesaconclusionandthefutureworkabouttheproject.
2LiteratureReview
2.1Overview
Toovercomethelackofmultipleantennaslimitedbysizeorhardwarecomplexity,cooperativecommunicationisproposed.Cooperativecommunicationcanbeunderstoodavirtualmultipleinputmultipleoutput(MIMO)systembetweensourceanddestination.
Inanotherwords,thecooperativecommunicationbuildacooperativerelationshipamongexistingantennas.Forutilizingthebroadcastpropertyofelectromagnetismwave,notonlythedestination,therearealsosomeotherantennasreceivethesourcesignal.Insteadofdiscardingthissignal,thisrelationshipaskstheseantennastotakesomemeasurestoprocessthissignalandretransmitittotheappointeddestination.
Todecreasethebiterrorrateandrecoverthesourcesignalwell,therearethreecommonprotocolsforthehelperantennasapplying:
amplifyandforward(AF)protocol,decodedandforward(DF)protocolandcodedcooperative(CC)protocol.
Figure2.2Cooperativecommunication
2.2Spatialdiversitytechnology
Cooperativecommunicationutilizesthespatialdiversitytechnology.Diversityisanideathattransmittingasignalthroughmanyindependentchannels,itisdescribedin[1].Whensourcesendsonesignalindifferentindependentchannels,thedestinationwillreceivemanyformatsaboutthissignal.Inthisway,itcanincreasethesignal-to-noiseratio(SNR)atthereceiverwhichresultinrecoveringthesourcesignalbetter.Therearethreecommondiversitytechnologies:
timediversity,frequencydiversityandspatialdiversity.Spatialtechnologyistobuildmanyrelaystoretransmitthesignalwhichcreatesadditionalchannelsinspace.Thecooperativec
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