简介:一种技术把重叠频率时间分割称为multiplexing(OVFTDM))在这篇文章被建议。这种技术从Nyquist系统和频率时间部门multiplexing系统被导出。没有orthogonality,信号是什么时候,简洁地及时重叠了领域,,当没有orthogonality,信号简洁地在频率领域被重叠时,这种技术被称为重叠时间部门multiplexing(OVTDM),这种技术被称为重叠频率部门multiplexing(OVFDM)。进一步改善光谱效率,在哪个发信号的OVFTDM在频率领域两个都被重叠,及时,域被探索。OVFTDM不取决于无论什么的orthogonality及时域或在象Nyquist系统或OFDM系统一样的频率领域,但是在在信号之中的convolutional限制关系上。因此,不是仅仅光谱效率而且可靠性被改进。模拟验证这个理论的有效性。
简介:Thestatisticcharacteristicsofchaoticsequencesgeneratedbyimprovedlogistic-mapareanalyzedanditisfoundthatimprovedlogistic-mapchaoticsequenceshavegoodcorrelationandtheycanbeusedasaddresssequencesinspread-spectrumcommunication.Thediscrete-timesynchronizationofHenonmapisimmediate.Weapplythediscrete-timesynchronizationtochaoticspread-spectrumcomuunicationandproposeanoriginalcommunicationscheme.Thesimulationshowsthattheapplicationissuccessful.
简介:Accuratetimedelayestimationisveryimportantinmultichannelnoisesuppressionsystems.Thispaperhasproposedanewmethodtoreducetheeffectofnoiseontheestimationoftimedelaybetweendifferentchannels.Ournewtimedelayalgorithmwillmoreconsiderablyreducetheestimationerror,comparedwiththeconventionalautocorrelationfunctionmethod.
简介:Storingthewholedatabaseinthemain-memoryisacommonmethodtoprocessreal-timetransactioninreal-timedatabasesystems.TherecoverymechanismofMain-memoryReal-timeDatabaseSystems(MMRTDBS)shouldreflectthecharacteristicsofthemain-memorydatabaseandreal-timedatabasebecausetheirstructuresarequitedifferentfromotherconventionaldatabasesystems.Inthispaper,therefore,weproposeamulti-levelrecoverymechanismformain-memoryreal-timedatabasesystemswithExtendibleChainedBucketHashing(ECBH).Owingtotheoccurrenceofreal-timedatainreal-timesystems,weshouldalsoconsideritinourrecoverymechanism.Accordingtoourperformancetest,thismechanismcanimprovethetransactionconcurrency,reducingtransactions'deadlinemissingrate.
简介:Consideringthejointchannelestimationanddatadetectionintime-varyingorthogonalfrequencydivisionmultiplexing(OFDM)andaddressingtransmissionperformancedegradationinducedbythesevereinter-carrierinterference(ICI)atveryhighspeed,anewprogressiveiterativechannelestimationschemeisproposed.ToalleviatetheerrorpropagationoftheinaccuratedataduetoICI,themeasurementsubcarriersintheKalmanfilterisdesignedtobeextendedfrompilotssubcarrierstoallthesubcarriersprogressivelythroughtheiterations.Furthermore,initerationprocess,theinterferenceofthenon-pilotdatatothemeasurementsubcarriersisconsideredtobepartofnoiseinthemodifiedKalmanfilter,whichimprovestheestimationaccuracy.Simulationindicatesthattheproposedschemeimprovestheperformanceinfasttime-varyingsituation.
简介:Opticaltimedivisonmultiplexing(OTDM)isoneofthepromisinigwaysforthefuturehigh-speedopticalfibercommunicationnetworks.All-opticalswitchis,beingoneofthecoretechnologiesofOTDMsystemsandnetorks,crucialtorealizethevaroussignalprocessesincludingtime-divisiondemultiplexing,packerswitching,all-opticalregeneratingandsoon.Thisthesismainlystudiesvariousall-opticalswitchtechnologiesandtheirutilizationinthefieldsofall-opticalsignalprocessingsintheOTDMsystemsandnetworks.Themainjobsarelistedasfollows.(1)Anovelall-opticalultrafastdemultiplexingschemeusingthesolitonself-trappingeffectinbirefringentfiberisproposed.(2)ThedemultiplexingperformanceoftheNonlinearOPticalLoopMirror(NOLM)isthoroughlyanalyzedanditsoptimizationisfurtherdiscussed.(3)Theperformanceanalysisandtheconfigurationoptimizationoftheall-opticalswitchesbasedontheSemiconductorOpticalAmplifier(SOA)aresystematicallypresented.Thespeedlimitationoftheall-opticalSOAswitchesinducedbythefastgaindepletionofSOAisdiscussed,Besides,anovelSOAswitchisproposed,whichadoptstheasymmetricMach-ZehnderInterferomerterconfiguration.(4)The8×2.5Gb/sOTDMexperimentaltransmissionsystemalong105kmstandardfiberisrealizedusingtheNOLMdemultiplexer.(5)TheNOLMswitchisusedtorealizetheall-optical3Rregenerationof2.5G/sReturn-to-Zerosignal.(6)ThefeasibilityandlimitationoftheallopticalSOApacketswitchisdiscussed.AndadevelopedMZIconfigurationofSOApacketswitchisfurthershowntoimprovethepackerswitchingperformance.Finally,anall-opticalpacketdroppingnodesuitableinthenetworkswithringorbusconfingurationandanall-opticalpacketswithcingnodeintheShuffleNetnetworksareproposedtoshowthefeasibilityofall-opticalpacketswitchingthroughcombiningtheall-opticalswitchesandthereasonablelogicdecisions.
简介:与高精确性提取multipath的参数能被为时间域使用高分辨率的算法完成极端宽带(UWB)隧道建模。干净算法为UWB时间域描述被用作如此的一个高分辨率的算法。这份报纸论述压缩察觉到(CS)为时间域UWB隧道建模基于高分辨率的deconvolution算法。UWB无线隧道是长、稀少的隧道推动反应(CIR)的一个主要例子。而且,仔细匹配multipath的波形的parameterized波形的字典导致UWB隧道测量信号更简洁地被代表。由调整字典的参数,不同分辨率的CIR能被获得。匹配的追求(MP)算法为CS被用作信号重建方法并且直接输出CIR。我们也证明如果CS的字典明确地被设计,MP是单个模板的等价物干净。最后,CS-MP的计算复杂性被分析并且MP的比较并且干净被执行。模拟结果显示出那与相比干净,建议CS-MPdeconvolution算法能与许多少数完成可比较的表演采样。
简介:Andynamicsystemforreal-timeobstacleavoidancepathplanningofredundantrobotsisconstructedinthispaper.Firstly,theinter-framedifferencemethodisusedtoidentifythemovingtargetandtocalculatethetargetarea,thenonthebasisofcolorfeaturesandgradientfeaturesextractedfromthetargetarea,thefeaturefusionCam-Shiftmeanshiftalgorithmisusedtotracktarget,improvingtherobustnessofthetrackingalgorithm.Secondly,aparalleltwo-channeltargetidentificationandlocationmethodbasedonbinocularvisionisproposed,updatingthetarget’sthree-dimensionalinformationinrealtime.Then,adynamiccollision-freepathplanningmethodisimplemented:thesafetyrodsareremovedthroughtheintersectiontest,andtheminimumdistanceisderiveddirectlybyusingthecoordinatevaluesofthetargetinthelocalcoordinatesystemoftherod.Onthisbasis,theobstacleavoidancegainandescapevelocityrelatedtotheminimumdistanceisestablished,andobstacleavoidancepathplanningisimplementedbyusingthezerospacemappingmatrixofredundantrobot.Experimentsareperformedtostudytheefficiencyoftheproposedsystem.
简介:AnovelandefficienttechniquetodesignmodulateddiscreteFouriertransform(DFT)filterbanksisintroducedinthispaper.Theproposedmethodfirstrelaxesthelimitsthatthesynthesisfiltersarethetime-reversedversionoftheanalysisfiltersandthenadoptsthetimedomainformulaoftheperfectreconstructionpropertyasthesolutiontodesignthesynthesisfilters.TheprototypefilterinanalysisfilterbanksisdesignedbasedonFourier-Kaiserwindowapproach.Simulationresultsshowthatthedesignedfilterbanksapproximatelysatisfytheperfectreconstructionwithcontrollablereconstructionerrors.
简介:Thispaperaddressestheissueofreal-timedatatransmissioninvehiclestoroadside(V2R)environmentbythehybridcoordinationfunction(HCF)ofcontrolledchannelaccess(HCCA)specifiedbytheIEEE802.11pstandard.HCCAisoneofthemediumaccessmechanismsintheIEEE802.11standard,andusesthepollingschemesimilartothepointcoordinationfunction(PCF)toprovidereliablequalityofservice(QoS),whichmaycauseresourceovershootingandhightimeconsuming.ThispapertriestoimprovetheperformanceoftheHCCApollingschemeanddesignsnewdatatransmissionschedulingscheme.Thesimulationresultsoftheproposalarecomparedwiththoseofthestandardstrategy.SimulationresultsdemonstratethattheimprovedHCCAhaslowerdelay,lossrate,andhigherthroughputthanthoseofthestandardone.
简介:是的巨大的部门操作广泛地为象图形的处理那样的设备作为最昂贵的操作之一接受了联合起来的完美地匹配的层(CPML)算法受不了的卷绕旋转的平行加速(GPU),地可编程的门数组(FPGA)等等。在更高的效率和更低的电源消费的追求,这篇文章重游CPML理论并且建议了新快没有部门的平行CPML结构。由最佳地重排CPML内部重复进程,所有部门操作符能被recalculating消除并且代替脱机更新系数的相关的域。实验证明没有任何精确性损失,建议没有部门的结构能节省超过50%算术指令和传统的平行CPML结构的25%实行时间。
简介:Inlongtermevolution(LTE)uplinksinglecarrierfrequencydivisionmultipleaccess(SC-FDMA)system,therestrictionthatmultipleresourceblocks(RBs)allocatedtoausershouldbeadjacent,makestheresourceallocationproblemhardtosolve.Moreover,withthepracticalconstraintthatperfectchannelstateinformation(CSI)cannotbeobtainedintime-varyingchannel,theresourceallocationproblemwillbecomemoredifficult.Inthispaper,anefficientresourceallocationalgorithmisproposedinLTEuplinkSC-FDMAsystemwithimperfectCSIassumption.Firstly,theresourceallocationproblemisformulatedasamixedintegerprogrammingproblem.Thenanefficientalgorithmbasedondiscretestochasticoptimizationisproposedtosolvetheproblem.Finally,simulationresultsshowthattheproposedalgorithmhasdesirablesystemperformance.