协同通信与AF和DF中继协议详情.docx

协同通信与AF和DF中继协议详情.docx

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协同通信与AF和DF中继协议详情

Abstract

Nowadays,thereisatrendforcommunicationsystemthatthewholenetworksystemisbecomingdynamicsothattherearealwayshavingdevicesshouldbeembeddedandremoved.Conventionalwiredcommunication,duetothecomplexityofcabling,doesnotadapttothemoderncommunicationsystem.Wirelesstechniquehasbeenusedwidelybecausedevicescanbeconnectedbyelectromagnetismwavewithoutcabling.However,lowtransmittingreliablitybecauseofinter-interferencebetweenelectromagnetismwavesisthekeyproblemofwirelesscommunication.Basedonthis,thisthesisinvestigatesoneofthetechniquecalledcooperativecommunicationanditcooperativeprotocols.

Cooperativecommunicationisavirtualmultiple-inputmultiple-output（MIMO）system.Toincreasethereliabilityofsignaltransmittedwithoutincreasingtheamountofcommunicationdevices,thistechnologytriestomakeeachantennashaveoneormorepartnersthatassistthemtotransmitthesignal.Inwirelessnetwork,thedevicesnotonlytransmittheirownsignalbutalsoassisttheir“partner”totransmittheirsignalforsavingthecostofinstallationofadditionalantennasatbothreceiverandsender

Inthisthesis,wefocusonintroducingthreemainprotocolsincooperativecommunication:

Amplify-and–Forward（AF）,Decode-and-Forward（DF）andCodedCooperation（CC）.TheperformanceandmathematicalequationsofAFandDFareanalysed,andthenMATLABprogramswerecreatedtosimulatetheperformanceofthesetwoprotocols.

Aboutthethreeprotocols,themainproceduresarealsointroduced.TheperformancecomparisonforAFandDFindifferentsignal-to-noise（SNR）aredemonstrated.TheresultpresentsthattheDFprotocolshasbetterperformancethanAF.Finally,somerecommendationsandfutureworkarementionedattheendofthethesis.

TableofContents

Abstract

Tableofcontains

Listoffigures

ListofabbreviationsandSymbols

1Introduction..................................................................................................................................9

1.1Background.......................................................................................................................9

1.2Objectives.........................................................................................................................9

1.3Approaches.......................................................................................................................9

1.4Thesisoutline....................................................................................................................10

2LiteratureReview.......................................................................................................................12

2.1Overview...........................................................................................................................12

2.2Spatialdiversitytechnology..............................................................................................13

2.3BasicModelforWireless...................................................................................................13

2.3.1SISOsystem............................................................................................................13

2.3.2MIMOsystem.........................................................................................................14

2.3.3Cooperativemodel.................................................................................................14

2.4Cooperativeschemes........................................................................................................15

2.4.1Amplify-and-forwardmethod................................................................................16

2.4.2Decode-and-forwardmethod................................................................................16

2.4.3Codedcooperation.................................................................................................17

3SimulationandAnalysesofAF..................................................................................................21

3.1Overview...........................................................................................................................21

3.2Maximumlikelihoodmethod............................................................................................21

3.3SimulationandAnalysis.....................................................................................................21

3.3.1Thewholeprocedureandanalysis.........................................................................21

3.3.2Simulation..............................................................................................................24

3.4Summary...........................................................................................................................26

4SimulationandAnalysisofDF...................................................................................................27

4.1Overview..........................................................................................................................27

4.2Quantizationmethod.......................................................................................................27

4.3ConvolutionalCodeandViterbidecode..........................................................................27

4.3.1Convolutionalcode...............................................................................................28

4.3.2Viterbidecode.......................................................................................................28

4.4Simulationandanalysis....................................................................................................28

4.4.1Thewholeprocedureandanalysis........................................................................29

4.4.2Simulation..............................................................................................................30

4.5PerformancecomparisonbetweenAFandDF................................................................31

4.6Mainchallenges................................................................................................................32

4.7Summary...........................................................................................................................33

5Conclusionsandfuturework.....................................................................................................34

5.1Conclusion.........................................................................................................................34

5.2Prospect............................................................................................................................34

5.3Futurework.......................................................................................................................35

Reference...................................................................................................................36

AppendixAThesisspecification..................................................................................37

AppendixBLogbookSummarySignature....................................................................40

AppendixCMATLABprograms....................................................................................41

C.1Amplify-and-ForwardProtocol……………………………………………………………….........……41

C.2Decode-and–Forwardprotocol……………………………………………………..................……42

C.3Rayleighchannel………………………………………………………......................................…..45

ListofFigures

Figure2.1virtualMIMOsystem………………………………………………………………………............….….…..13

Figure2.2Cooperativecommunication………………………………………………………………………….....……14

Figure2.3MIMOsystem…………………………………………………………………………………………….......……..15

Figure2.4Cooperativemodel…………………………………………………………………………………….......……..16

Figure2.5Relayamplifymodel………………………………………………………………………………………...……..17

Figure2.6Decodedandforwardmodel…………………………………………………………………………..……….18

Figure2.7Codedcooperativemodel…………………………………….........………………………………...........19

Figure2.8Codedcooperationdataallocation…………………………………………………………..………...…….20

Figure2.9Fourcasesincodedcooperative……………………………………………………………......……………20

Figure3.1firsttimeslotinAFmethod………………………………………………………………..…......…....…….23

Figure3.2SecondtimeslotinAFmethod………………………………………………………………….……………..24

Figure3.3AFprotocolBERdiagram……………………………………………………………………………………..…..26

Figure4.1（n,k,m）convolutionalencoder…………………………..……………………………………………....…….29

Figure4.2firsttimeslotofDF…………………………………………………………………………………………………….30

Figure4.3Secondtimeslot…………………………………….........…………………………………………………….…..30

Figure4.4DFprotocolBERdiagram……………………………………………………………………………………….....32

Figure4.5DFwholeprocedures……………………………..………………………………………………………...……..32

Figure4.6performancecomparedbetweenAFandDF…….....................………………………….………33

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,therearealsomanyproblemsappear