简介:Consideringthejointchannelestimationanddatadetectionintime-varyingorthogonalfrequencydivisionmultiplexing(OFDM)andaddressingtransmissionperformancedegradationinducedbythesevereinter-carrierinterference(ICI)atveryhighspeed,anewprogressiveiterativechannelestimationschemeisproposed.ToalleviatetheerrorpropagationoftheinaccuratedataduetoICI,themeasurementsubcarriersintheKalmanfilterisdesignedtobeextendedfrompilotssubcarrierstoallthesubcarriersprogressivelythroughtheiterations.Furthermore,initerationprocess,theinterferenceofthenon-pilotdatatothemeasurementsubcarriersisconsideredtobepartofnoiseinthemodifiedKalmanfilter,whichimprovestheestimationaccuracy.Simulationindicatesthattheproposedschemeimprovestheperformanceinfasttime-varyingsituation.
简介:Gettingalongwiththeimprovementofgreencommunications,theenergyefficiency(EE)ofwirelessnetworkbecomesmoreandmoreimportant.However,inmulti-relay-assistedsystems,therelatedworkobviouslydependsontheend-to-endperformance,whereasEEofrelayshasnotattractedenoughattention.Theauthorsproposeanorthogonalfrequencydivisionmultiplexing(OFDM)multi-relaysystembasedonamplifyandforward(AF)mode.TakingincorporatingEEandremainingenergyasfactor,decisioncriteriaofattendingcooperationisdesigned.TheEEbasedasynchronouspoweriterationmethodispresented,andtheexistenceandconvergenceofnashequilibrium(NE)isproven.Furthermore,ajointalgorithminsubcarrierpairing,relayselectionandpowerallocationisgiven.Geneticalgorithm(GA)anditerationmethodareintegratedtoimprovetheconvergencespeedadditionally.SimulationdemonstratestheobviousimprovementofEE,decreaseofpowerconsumptionandincreaseoflifetimeinrelaysofthisalgorithmwiththeconstraintofminimumdatatransmissionrate.
简介:Thisletterpresentsalowcostsolutionforwavelengthdivisionmultiplexedorthogonalfrequencydivisionmultiplexedpassiveopticalnetwork(WDM-OFDM-PON)withwidelytunableopticalfilterandlinearsmallform-factorpluggable(SFP)module.With9-nmtunablerangefrom1551to1560nm,thetunablefiltercansupportupto10-channel100-GHzspacingWDMPONsystem.Alinearavalanchephotodiode(APD)basedSFP+moduleisdesignedforopticalOFDMsignaldemodulation,whichcanprovidebetterreceiverperformancecomparedwithlimitingAPDmodule.Experimentalresultsshowthat~34dBpowerbudgetcanbeachievedin4×5-GbpsWDM-OFDM-PONsystem,whichcansatisfythetransmissionrequirementsofnextgenerationPONsystem.
简介:ByusingPDM-OFDM-16QAMmodulation,all-Ramanamplification,coherentdetection,and7%forwarderrorcorrection(FEC)threshold,wesuccessfullydemonstrate63-Tb/s(368×183.3-Gb/s)signalover160-kmstandardsinglemodefiber(SSMF)transmissionintheC-andL-bandswith25-GHzchannelspacing.368opticalchannelswithbandwidthspacingof25GHzaregeneratedfrom16externalcavitylasersources.After160-kmSSMFtransmission,alltestedbiterrorrate(BER)areunder3.8×10-3,whichcanberecoveredby7%FECthreshold.Withineachchannel,weachievethespectralefficiencyof6.85bit/s/HzinC/Lband.