a study on the impact of nonlinear characteristics of …

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1、AStudyontheImpactofNonlinearCharacteristicsofLEDsonOpticalOFDMbyHanyElgalaAthesissubmittedinpartialfulfilmentoftherequirementsforthedegreeofDoctorofPhilosophyinElectricalEngineering2Approved,ThesisCommittee:Prof.Dr.HaraldHaasJacobsUniversity,GermanyUniversityofEdinburgh,U

2、KProf.Dr.WernerBergholzJacobsUniversity,GermanyDr.DominicO’BrienUniversityofOxford,UKDateofDefense:March29,2010SchoolofEngineeringandScienceAStudyontheImpactofNonlinearCharacteristicsofLEDsonOpticalOFDMPhDThesisbyHanyElgalaSchoolofEngineeringandScienceJacobsUniversityMar

3、ch2010SchoolofEngineeringandScienceJacobsUniversityPhDThesisAStudyontheImpactofNonlinearCharacteristicsofLEDsonOpticalOFDMAbstract:“Thetrulylearnedmanishewhounderstandsthatwhatheknowsisbutlittleincomparisonwithwhathedoesnotknow.”(AliBinAby-Talib(r.a))Inthe21thcentury,the

4、demandforwirelessbandwidthwillcontinuetoincreasetoservebandwidth-intensiveapplicationssuchashighdefinition(HD)videostreamingviaInternet.Theexistingradiofrequency(RF)technologystandards,i.e.theIEEE(instituteofelectricalandelectronicsengineers)802.11a/b/g/nstandards,sufferfr

5、omthebandwidthbottleneck.However,opticalwireless(OW)technologyhasthepotentialforbeinganattractivecomplementarytorealizebroadbandwirelessaccessindoors.Recently,indoorOWcommunicationsystemsbasedonlightemittingdiode(LEDs)aslightsourcesandorthogonalfrequencydivisionmultiplex

6、ing(OFDM)asamodu-lationtechniquehavegainedsignificantattention.Forinstance,invisiblelightcom-munication(VLC),inadditiontolighteningcapabilitiesofwhiteLEDs,theycanbemodulatedtoachievehigh-speedwirelessdatatransmission.OpticalOFDM(O-OFDM)systemsareabletosupporthighdatarates

7、throughparalleltransmissionofhighordermulti-levelquadratureamplitudemodulation(M-QAM)symbolsonorthogonalsubcar-riers.Complexchannelequalizersarenotrequiredandthetime-varyingchannelcanbeeasilyestimatedusingfrequency-domainchannelestimation.Adaptivemodulationpersubcarrierc

8、anbeeasilyrealizedbasedontheuplink/downlinkrequesteddataratesandqualityofservice(QoS).Also,theinherentr