简介:Currently,1bitor2bitsignalquantizationiswidelyusedinsatellitenavigationsoftwarereceivers.Thebit-wiseparallelalgorithmhasbeenproposedfor1bitand2bitsignalquantization,whichperformscorrelationwithhighefficiency.Inordertoimprovetheperformanceofthecorrelator,thispaperproposesanew1.5bitquantizationmethod.Theoreticalanalysesaremadefromtheaspectsofcomplexityandquantizationloss,andperformancecomparisonbetween1.5bitquantizationcorrelatorandtraditionalcorrelatorsisdiscussed.Theresultsshowthatthe1.5bitquantizationalgorithmcansaveabout30percentcomplexityundersimilarquantizationloss,reducemorethan0.5dBsignalnoiseratio(SNR)lossundersimilarcomplexity.Itshowsgreatperformanceimprovementforcorrelatorsofsatellitenavigationsoftwarereceivers.
简介:瞄准充分利用类似物到当保留山峰平均比率(同等)时,没有oversaturation,digitalizing咬了的数字变换器(模数转换器)稳定,这份报纸提出一新分割完整数字(SFD)为新长期的进化(LTE)的自动获得控制(自动增益控制)算法通讯系统。分割的数字获得控制策略被采用基于检测力量地位由仅仅一步调整获得。要调整的获得需要是否由当前的信号状态被决定,源于输入信号和目标信号的邻近的根平均数平方(RMS)的变化范围。实现的软件模拟和硬件与LTE频率分割被进行了双(软式磁碟机)uplink信号和结果显示建议自动增益控制算法能精确地判定力量地位并且进一步,因此与短延期在一步精确调整获得没有oversaturation,它能象使同等稳定一样充分利用模数转换器digitalizing小点。另外,吝啬的错误向量大小(EVM)被限制不到1.6%投射遇见第三产生合伙(3GPP)标准很好。
简介:Inthispaper,weproposeoptimumandsub-optimumresourceallocationandopportunisticschedulingsolutionsfororthogonalfrequencydivisionmultipleaccess(OFDMA)-basedmulticellularsystems.Theapplicability,complexity,andperformanceoftheproposedalgorithmsareanalyzedandnumericallyevaluated.Intheinitialsetup,thefractionalfrequencyreuse(FFR)techniqueforinter-cellinterferencecancellationisappliedtoclassifytheusersintotwogroups,namelyinteriorandexteriorusers.Adaptivemodulationisthenemployedaccordingtothechannelstateinformation(CSI)ofeachusertomeetthesymbolerrorrate(SER)requirement.Therethen,wedevelopsubcarrier-and-bitallocationmethod,whichmaximizesthetotalsystemthroughputsubjecttotheconstraintsthateachuserhasaminimumdataraterequirement.Thealgorithmtoachievetheoptimumsolutionrequireshighcomputationalcomplexitywhichhindersitfrompracticability.Towardthisend,weproposeasuboptimummethodwiththecomplexityextensivelyreducedtotheorderofO(NK),whereNandKdenotethetotalnumberofsubcarriersandusers,respectively.Numericalresultsshowthattheproposedalgorithmapproachestheoptimumsolution,yetitenjoysthefeaturesofsimplicity,dynamiccellconfiguration,adaptivesubcarrier-and-bitallocation,andspectralefficiency.IndexTermsAdaptivemodulation,fractionalfrequencyreuse,multiusersubcarrier-and-bitallocation,opportunisticscheduling,orthogonalfrequencydivisionmultipleaccess.
简介:Theconceptofdualimagereversibledatahiding(DIRDH)isthetechniquethatcanproducetwocamouflageimagesafterembeddingsecretdataintooneoriginalimage.Moreover,notonlycanthesecretdatabeextractedfromtwocamouflageimagesbutalsotheoriginalimagecanberecovered.Toachievehighimagequality,Luetal.'smethodappliedleast-significant-bit(LSB)matchingrevisitedtoDIRDH.Inordertofurtherimprovetheimagequality,theproposedmethodmodifiesLSBmatchingrevisitedrulesandappliesthemtoDIRDH.Accordingtotheexperimentalresults,theimagequalityoftheproposedmethodisbetterthanthatofLuetal.'smethod.
简介:Thestructureoftheopticalwaveguideof2-bitelectroopticA/Dconverterwithproton-exchangemicroprismsisoptimizedbythefinite-differencebeampropagationmethod(FD-BPM).Theelectrodeparametersoftheconverterareoptimizedbyconformalmapping.Theoptimalparametersareahalf-wavevoltageofVπ=4.5VandabandwidthofΔf=1.4GHz.Anormalizedtransmittedpowerof69.75%isobtainedbyFD-BMPandtheoutputwaveguidegapis300μm.
简介:Thepapermainlystudiesthesum-rateperformanceoflimitedfeedback(LFB)block-diagonalization(BD)inmulti-userdistributedantennasystem(DAS).Asthechannelstateinformation(CSI)fedbacktobasestation(BS)islimited,multi-userinterference(MUI)iscausedinevitablybecauseofthequantizationerror.ConsideringtheinfluenceoftheMUItothecapacityofDAS,weproposeaparameterofeffectivesum-rateratio(ESRR)todenotethecapacityoffsetundertheconditionoftheBScangetperfectCSIandlimitedCSIfirst,thenweconfirmthattheapproximatedESRRisveryclosetoactualESRRgotthroughsimulations.Afterthat,basedontheapproximatedESRR,anadaptiveminimumbitfeedbackschemewhichcaneffectivelyreducetheoverheadoffeedbackchannelandthecomplexityofthesystemisproposed.Simulationresultsshowtheeffectivenessoftheproposedscheme.
简介:中科院微电子所微波器件与集成电路研究室HBT超高速电路小组在刘新宇研究员和金智研究员的带领下研制成功两款基于1μmGaAsHBT工艺的8bit超高速直接数字频率综合器(DirectDigitalfrequency-Synthesizer,DDS)芯