简介：Anoveluniversalpreprocessingmethodisproposedtoestimateanglesofarrival,whichisapplicabletoone-ortwo-dimensionalhighresolutionprocessingbasedonarbitrarycenter-symmetricarrays(suchasuniformlineararrays,equal-spacedrectangularplanararraysandsymmetriccirculararrays).Bymappingthecomplexsignalspaceintotherealone,thenewmethodcaneffectivelyreducethecomputationneededbythesignalsubspacedirectionfindingtechniqueswithoutanyperformancedegradation.Inaddition,thenewpreprocessingschemeitselfcandecorrelatethecoherentsignalsreceivedonthearray.Forregulararraygeometrysuchasuniformlineararraysandequal-spacedrectangularplanararrays,thepopularspatialsmoothingpreprocessingtechniquecanbecombinedwiththenovelapproachtoimprovethedecorrelatingability.Simulationresultsconfirmtheaboveconclusions.

简介：Thispaperdiscussestheproblemofdirectionofdeparture(DOD)anddirectionofarrival(DOA)estimationforabistaticmultipleinputmultipleoutput(MIMO)radar,andproposesanimprovedreduced-dimensionCaponalgorithmtherein.Comparedwiththereduced-dimensionCaponalgorithmwhichrequirespairmatchingbetweenthetwo-dimensionalangleestimation,theproposedalgorithmcanobtainautomaticallypairedDODandDOAestimationwithoutdebasingtheperformanceofangleestimationinbistaticMIMOradar.Furthermore,theproposedalgorithmhasalowercomplexitythanthereduced-dimensionCaponalgorithm,anditissuitablefornon-uniformlineararrays.ThecomplexityoftheproposedalgorithmisanalyzedandtheCramer-Raobound(CRB)isalsoderived.Simulationresultsverifytheusefulnessoftheproposedalgorithm.

简介：Parameterestimationofsignalsofuniversalsoftwareradioperipheral(USRP)devicesiscrucialtosolvetheproblemofphaseoffsetsofreceivedsignalsindistributedbeamforming.Forsystemsthatwillutilizetheclosedloopfeedbackalgorithmwherethereceiverneedstosendthereceivedsignalstrength(RSS)valuesperiodicallytothebeamformingnodesoastotakeadvantageofenergyconservation,thefrequencyandphaseofthesesignalsshouldbeestimatedbeforesmootheningbynonlinearfilters.ThisarticlepresentstheestimationofthefrequencyoffsetsofaGaussianminimumshiftkeying(GMSK)signalfromN210USRPdevicesinrealtimebyusingtheRadix-2fastFouriertransform(FFT)algorithminGNURadio.Forthesegreencommunicationsdevices,mostoftheneededhardwarepartshavebeensoftwaredefined,therebyreducingthesupposedenergyconsumption.Thefrequencyoffsetsfromreferencecarrierfrequenciesof900MHzand2.4GHzarelessthan3kHzeachbeforetheestimation,buttheaverageoffsetsare45Hzand100Hzaftertheestimation,respectively.Thehighoffsetvalueexperiencedwiththe2.4GHzcarrierwasduetoconsistentinterferencefromdevicesonthatsamefrequency.

简介：Multipathtimedelayestimationisconstrainedbythewidthofthesignalcorrelationfunctionwhenusingcorrelationbasedmethods.ThispaperobtainsahighresolutiontimedelayestimationbyintroducingBurgalgorithmandMarplealgorithmofthemaximumentropypowerspectralestimationtonon-resolvablemultipathtimedelayestimatoin.Theprinciples,theperformacesandtheresultsofcomputersimulationaregiven.

简介：BasedonEvans’spatialsmoothingpreprocessingscheme,anewapproachcalledtwo-directionspatialsmoothingpreprocessingmethodispresented.Itisprovedthatthedecorre-lation,theeffectiveapertureandthemaximumnumberofdistinguishablecoherentsignals(whenarraysizeisgiven)ofthenewmethodarebetterthanthoseoftheEvans’method.Simulationresultsgiveacomparisonbetweentheeigenvectorspectrumsproducedbythetwomethods.

简介：Aimingtoreducethecomputationalcostsandconvergetoglobaloptimum,anovelmethodisproposedtosolvetheoptimizationofacostfunctionintheestimationofdirectionofarrival(DOA).Inthismethod,ageneticalgorithm(GA)andfuzzydiscreteparticleswarmoptimization(FDPSO)areappliedtooptimizethedirectionofarrivalandpowerparametersofthemodesimultaneously.Firstly,theGAalgorithmisappliedtomakethesolutionfallintotheglobalsearching.Secondly,theFDPSOmethodisutilizedtonarrowdownthesearchfield.InFDPSO,achaoticfactorandacrossovermethodareaddedtospeeduptheconvergence.Thisapproachhasbeendemonstratedthroughsomecomputationalsimulations.ItisshownthattheproposedalgorithmcanestimateboththeDOAandthepowersaccurately.Itismoreefficientthansomepresentmethods,suchastheNewton-likealgorithm,Akaikeinformationcritical(AIC),particleswarmoptimization(PSO),andgeneticalgorithmwithparticleswarmoptimization(GA-PSO).

简介：Toestimatethespreadingsequenceofthedirectsequencespreadspectrum(DSSS)signal,afastalgorithmbasedonmaximumlikelihoodfunctionisproposed,andthetheoreticalderivationofthealgorithmisprovided.Bysimplifyingtheobjectivefunctionofmaximumlikelihoodestimation,thealgorithmcanrealizesequencesynchronizationandsequenceestimationviaadaptiveiterationandslidingwindow.Sinceitavoidsthecorrelationmatrixcomputation,thealgorithmsignificantlyreducesthestoragerequirementandthecomputationcomplexity.Simulationsshowthatitisafastconvergentalgorithm,andcanperformwellinlowsignaltonoiseratio(SNR).

简介：Themobilechannelisslowfadingandtimeselective,thusthemultiplicativeandadditivenoiseofthechannelwillsmearthespectralline,orarouseDopplerspread.Thisspreadwillmaketheparametersestimationaccuracydegrade.ThegoalofthispaperistoanalyticallyassessthisdegradationwhenCarrierFrequencyOffset(CFO)andDopplershiftexistjointly.Thenthefinite-sampleCramer-RaoLowerBound(CRLB)isderivedandclose-formasymptoticalexpressionisgivenforlarge-sampleCRLB.Theseexpressionsgiveinsightsintotheperformanceroomforfrequencyestimation.AlsothevarianceofDopplershiftestimatorissimulatedtoillustratethetheoreticalresults.

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简介：Theoptimalestimationperformanceoftargetparametersisstudied.First,thegeneralformofCramer-Raobound(CRB)forjointestimationoftargetlocationandvelocityisderivedforcoherentmultipleinputmultipleoutput(MIMO)radars.TogainsomeinsightintothebehavioroftheCRB,theCRBwithasetofgivenorthogonalwaveformsisstudiedasaspecificcase.Second,amaximumlikelihood(ML)estimationalgorithmisproposed.Themeansquareerror(MSE)oftheMLestimationoftargetlocationandvelocityisobtainedbyMonteCarlosimulationanditapproachesCRBinthehighsignal-to-noiseratio(SNR)region.

简介：Thispaperconsidersafrequency-divisionduplex(FDD)two-waychannelwithchannelestimationerror,wherechannelgainsareindependentofeachother.Itderivestheexactclosed-formoutageprobabilityexpressionsintheFDDsystemwithanalognetworkcoding(ANC)byuseofprobabilitytheory.Toprovidemoreinsights,anapproximatedversionfortheexactoutageprobabilityisalsodevelopedinthemedium-to-highsignal-to-noiseratio(SNR)region.ThesimulationresultsshowthatthederivedexactoutageprobabilitiesmatchtheresultsofMonteCarlosimulationsinallSNRregions,whiletheapproximatedoutageprobabilitiesalsoapproachthesimulationresultswhenthechannelconditionisgood.ItisinterestingthatANCintheFDDtwo-waychannelisprovedtooutperformthatofinthetime-divisionduplex(TDD)channelbythecomputersimulation.

简介：MostoftheblindOrthogonalFrequencyDivisionMultiplexing(OFDM)CarrierFrequencyOffset(CFO)estimatorsnecessitatelargenumberofsamplestoensuretheestimationaccuracy.However,thenumberofsamplescannotbeselectedtoolargebecauseofthecarrieroffsetdrift.Inthisletter,anewclosedformalgorithmforblindOFDMCFOestimationinfrequency-selectivechannelisproposed.Thismethodutilizesthepropagatorobtainedfromdatamatrixandthediagonalloadingtechnique,thusithasbetterperformanceevenonlyusingoneortwoOFDMblocks.Furthermore,therangeoftheCFOestimationwhichcanbehandledisoveralltransmissionspectral.Simulationresultsconfirmitseffectiveness.

简介：Thisarticleputsforwardanovelchannelestimationandinter-carrierinterference(ICI)suppressionmethodfortime-varyingorthogonalfrequencydivisionmultiplexing(OFDM)systems.Theproposedadaptivefiniteimpulseresponse(FIR)filterutilizesthetimedomaincorrelationofthesubcarriers.Basedontheoneorderauto-regressive(AR)model,amodifiedKalmanfilterisexploitedtotrackthechannelvariance.BysolvingtheYule-Walkerequation,thecoefficientoftheARprocesscanbeobtainedfromzeroorderBesselfunction.However,whenthechannelisassumednotperfectlyknown,theabovecriterionwillleadtoanimpracticalapplication.Todealwithit,thecoefficientoftheARprocessistakenasaconstant.Subsequentlyanewstatespacemodelisdeducedandfound.Simulationresultsshowthattheproposedmethodcanworkeffectivelyatthespeedof144km/hwithaphasenoiseof-85dBc/Hzat100kHzoffset.Theproposedmethodyieldsanimprovementbiterrorrate(BER)comparedwiththreeoftheexistingalgorithmswithmuchlowercomplexity.

简介：无人的天线车辆(UAV)遥远的成像被坏天气影响，并且获得的图象有低对比的劣势，复杂质地并且变模糊。在这份报纸，我们基于多重散布建议一个盲目deconvolution模型空气点传播功能(APSF)评价到恢复遥感图象。根据Narasimhan分析理论，一个新多重散布恢复模型基于改进二色的模型被建立。然后使用L0标准到估计APSF污迹核的坡度和黑暗隧道的稀少的priors，快Fourier变换被用来由过滤的维纳恢复原来的清楚的图象。由与另外的最先进的方法作比较，建议方法能正确地估计污迹核，有效地移开大气的降级现象，保存图象详细信息并且增加优秀评估索引。

简介：Inthispaper,weproposeanewmethodthatcombinescollageerrorinfractaldomainandHumomentinvariantsforimageretrievalwithastatisticalmethod-variablebandwidthKernelDensityEstimation(KDE).TheproposedmethodiscalledCHK(KDEofCollageerrorandHumoment)anditistestedontheVistextexturedatabasewith640naturalimages.ExperimentalresultsshowthattheAverageRetrievalRate(ARR)canreachinto78.18%,whichdemonstratesthattheproposedmethodperformsbetterthantheonewithparametersrespectivelyaswellasthecommonlyusedhistogrammethodbothonretrievalrateandretrievaltime.

简介：Waveletde-noisinghasbeenwellknownasanimportantmethodofsignalde-noising.Recently,mostoftheresearcheffortsaboutwaveletde-noisingfocusonhowtoselectthethreshold,whereDonohomethodisappliedwidely.Comparedwithtraditional2-bandwavelet,3-bandwavelethasadvantagesinmanyaspects.Accordingtothistheory,anadaptivesignalde-noisingmethodin3-bandwaveletdomainbasedonnonparametricadaptiveestimationisproposed.Theexperimentalresultsshowthatin3-bandwaveletdomain,theproposedmethodrepresentsbettercharacteristicsthanDonohomethodinprotectingdetailandimprovingthesignal-to-noiseratioofreconstructionsignal.

简介：新涡轮反复的接收装置结构为uplink被建议多重输入的多重产量的直角的频率分割多重存取(MIMO-OFDMA)系统。轮流出现空间的概括期望最大化(半自动地面防空系统)算法自然地在反复的接收装置的框架被嵌入用涡轮察觉者产量执行同步和察觉。在每次重复，期望步打算移开多重存取另外的异步的用户引起的干扰(MAI)，和最大化步被利用估计要求的参数(即，预定偏移量，搬运人频率偏移量，隧道状态信息，等等)顺序为每个用户。模拟结果证明建议算法能仔细接近理想的接收装置的表演，当处理复杂性比常规察觉者相当低时。

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简介：Aimingatthehigherbit-rateoccupationofmotionvectorencodingandmoretimeloadoffull-searchingstrategies,amulti-resolutionmotionestimationandcompensationalgorithmbasedonadjacentpredictionofframedifferencewasproposed.Differentialmotiondetectionwasemployedtoimagesequencesandproperthresholdwasadoptedtoidentifytheconnectedregion.Thenthemotionregionwasextractedtocarryoutmotionestimationandmotioncompensationonit.Theexperimentresultsshowthattheencodingefficiencyofmotionvectorispromoted,thecomplexityofmotionestimationisreducedandthequalityofthereconstructionimageatthesamebit-rateasMulti-ResolutionMotionEstimation(MRME)isimproved.

简介：A2D-directionofarrivalestimation(DOAE)formultiinputandmulti-output(MIMO)radarusingimprovedmultipletemporal-spatialsubspacesinestimatingsignalparametersviarotationalinvariancetechniquesmethod(TS-ESPRIT)isintroduced.InordertorealizetheimprovedTS-ESPRIT,theproposedalgorithmdividestheplanararrayintomultipleuniformsub-planararrayswithcommonreferencepointtogetaunifiedphaseshiftsmeasurementpointforallsub-arrays.TheTS-ESPRITisappliedtoeachsub-arrayseparately,andinthesametimewiththeotherstorealizetheparallellytemporalandspatialprocessing,sothatitreducesthenon-linearityeffectofmodelanddecreasesthecomputationaltime.Then,thetimedifferenceofarrival(TDOA)techniqueisappliedtocombinethemultiplesub-arraysinordertoformtheimprovedTS-ESPRIT.Itisfoundthattheproposedmethodachieveshighaccuracyatalowsignaltonoiseratio(SNR)withlowcomputationalcomplexity,leadingtoenhancementoftheestimatorsperformance.