简介:这篇文章在直角的频率部门multiplexing(OFDM)与min率要求限制处理multicast资源分配问题系统。由于为非线性、组合的优化的禁止地高的复杂性,原来的问题被放松并且形成一个标准优化问题的reformulated。根据Karush-Kuhn-Tucker(KKT)由理论推导调节,二项提议为optimality表现为必要标准。而且,包括副载波赋值和力量分配,一个二拍子的圆舞资源分配计划在实际实现的提议的一个基础上被建议。多点传送,min率基于组顺序,副载波以一种贪婪方式被分配最大化能力。当副载波赋值是坚定的时,建议力量分配能完成最佳的性能因为min率与可接受的复杂性抑制了能力最大化。模拟结果显示建议计划接近到彻底的搜索与可以忽略的能力差距获得的最佳的资源分配,并且更加超过相等的力量分发。同时,多点传送对在OFDM系统的资源利用显著地有益。
简介:Theproblemofimprovingtheperformanceofmin-sumdecodingoflow-densityparity-check(LDPC)codesisconsideredinthispaper.Basedonmin-sumalgorithm,anovelmodifiedmin-sumdecodingalgorithmforLDPCcodesisproposed.Theproposedalgorithmmodifiesthevariablenodemessageintheiterationprocessbyaveragingthenewmessageandpreviousmessageiftheirsignsaredifferent.Comparedwiththestandardmin-sumalgorithm,themodificationisachievedwithonlyasmallincreaseincomplexity,butsignificantlyimprovesdecodingperformanceforbothregularandirregularLDPCcodes.Simulationresultsshowthattheperformanceofourmodifieddecodingalgorithmisveryclosetothatofthestandardsum-productalgorithmformoderatelengthLDPCcodes.
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简介:Anovelfibergratingvibrationdemodulationsystem,basedon2×2and3×3couplers,isdesigned.Basedonthephaseunwrappingalgorithm,thethree-wayasymmetricaloutputofthe3×3coupleranddemodulationstatecharacteristicsofthesystemwhenthevibrationsignalincludeshighharmonicwavesareanalyzedinsimulations.Theresultshowsthatwhenthethree-wayoutputisasymmetrical,themaximumdeviationofdemodulationsignalis1.625%,andwhenthevibrationsignalincludeshighharmonicwaves,themaximumdeviationofdemodulationsignalis0.9%.Thecorrespondingexperimentisconducted.Theexperimentalresultshowsthatthedynamicresolutionofthesystemis25.22nε/Hzwhenthevibrationpitchis5.5Hz.
简介:Forenhancingthe2.0μmbandfluorescenceofHo3+,acertainamountofWO3oxidewasintroducedintoHo3+/Tm3+/Yb3+tri-dopedtelluriteglasspreparedusingmelt-quenchingtechnique.Thepreparedtri-dopedtelluriteglasswascharacterizedbytheabsorptionspectra,fluorescenceemissionandRamanscatteringspectra,togetherwiththestimulatedabsorption,emissioncross-sectionsandgaincoefficient.TheresearchresultsshowthattheintroductionofWO3oxidecanfurtherimprovethe2.0μmbandfluorescenceemissionthroughtheenhancedphonon-assistedenergytransfersbetweenHo3+/Tm3+/Yb3+ionsundertheexcitationof980nmlaserdiode(LD).Meanwhile,themaximumgaincoefficientofHo3+at2.0μmbandreachesabout2.36cm-1.Anintense2.0μmfluorescenceemissioncanberealized.
简介:Lanthanidehasattractedmuchattentioninthefieldofopticalcommunicationsinrecentyears.SomepropertyanalysesonopticalwaveguideofNd-dopedcrystalNdxY1-xAl3(BO3)4andNd:MgO:LiNbO3aremadeinthispaper,followedbyintroductionofthemethodsofexperimentationandtheoreticalcalculationfortheplanaropticalwaveguides.Therefractiveindexprofilesoftheopticalwaveguidesareanalyzed.Theaboveworkoffersusefulinformationforstudyonnewtypematerialsforopticalcommunications.