基站端无穷天线的非协作蜂窝无线通信-外文翻译

题目：NoncooperativeCellularWirelesswithUnlimitedNumbersofBaseStation1.Introductionoftheessay1.1Essay:NoncooperativeCellularWirelesswithUnlimitedNumbersofBaseStationAntennasChinesetranslation:基站端无穷天线的非协作蜂窝无线通信1.2whytochoosethisessayThisessayarewrittenbyTLMarzettawhoisfromBellLabs,anditiscitedbyotherarticlesmanytimes.Ityieldsanumberofmathematicallyexactconclusionsandpointstoadesirabledirectiontowardswhichcellularwirelesscouldevolve.Figure1Introductionoftheessay1.3backgroundoftheessayKeywords:Pilotcontamination（导频污染）,MassiveMIMOsystem（大规模输入输出系统）,Time-divisionduplex（时分复用）2.Words&ExpressionsWords&ExpressionsChinesetranslationscellular小区antenna天线basestation基站time-divisionduplex（TDD）时分复用frequency-divisionduplex（FDD）频分复用reverse-linkchannel反向信道forward-linkchannel前向信道pilot导频pilotcontamination导频污染channel-stateinformation（CSI）信道估计linearprecoder线性预编码fastfading快衰落log-normalshadowfading对数正态阴影衰落geometricattention几何衰落Words&ExpressionsChinesetranslationsinter-cellularinterferencesignal-to-interferenceratio（SIR）pilotsequencereusethroughoutcapacityspectrumefficiencyenergyefficiencyconjugate-transposepropagationmatrixzero-meanunit-variance小区内干扰信干比导频序列复用吞吐量容量频谱利用效率能量利用效率共轭转置传播矩阵均值为0方差为13.Translations3.1Inthelimitofaninfinitenumberofantennasacompletemulti-cellularanalysis,whichaccountsforinter-cellularinterferenceandtheoverheadanderrorsassociatedwithchannel-stateinformation,yieldsanumberofmathematicallyexactconclusionsandpointstoadesirabledirectiontowardswhichcellularwirelesscouldevolve.分析：句子的主语为acompletemulti-cellularanalysis，谓语为yields和pointsto为并列谓语。翻译：天线数量趋于无穷，完整的多小区分析解释了小区内干扰、额外的开销以及由信道估计信息引起的误差，得到了许多数学上准确的结论，并且指明了蜂窝无线通信发展令人满意得到方向。3.2Inparticulartheeffectsofuncorrelatednoiseandfastfadingvanish,throughputandthenumberofterminalsareindependentofthesizeofthecells,spectralefficiencyisindependentofbandwidth,andtherequiredtransmittedenergyperbitvanishes.分析：“areindependentof”本义为“不独立于”，这里可以翻译为“与...无关”翻译：尤其是，不相关噪声和快衰落的影响消失，吞吐量和终端数量与小区的规模无关，频谱利用效率与带宽无关，并且消除了每比特最小传输能量要求。Theonlyremainingimpairmentisinter-cellularinterferencecausedbyre-useofthepilotsequencesinothercells(pilotcontamination)whichdoesnotvanishwithunlimitednumberofantennas.翻译：唯一剩下的不足是由小区间导频序列复用引起的小区内干扰（导频污染）不会随着天线数量增加而消失。3.3Weconsideracellularsystemconsistingofnoncooperativehexagonalcellswithfrequencyre-useofone,three,orseven,TDDoperation,OrthogonalFrequencyDivisionMultiplexing(OFDM),andbasestationarrayscomprisingMantennaswhereM→∞,whereeachbasestationservesKsingle-antennaterminals.翻译：考虑到一个蜂窝系统由非协作的六边形小区构成，小区间的频率复用因子为1,3,7，使用TDD以及正交频分复用（OFDM），基站端有M根天线，M→∞,每个基站服务K个单天线的终端。3.4Severalapproximateconclusionshold:theoptimumnumberofterminalstoserve(fromthestandpointofmaximizingthemeanthroughput)isequaltoone-halfofthedurationofthecoherenceintervaldividedbythedelay-spread,thethroughputperterminalisindependentofthecoherencetime,theeffectofdoublingthecoherencetimeistopermittwiceasmanyterminalstobeserviced,andthereverse-linkperformanceisnearlyidenticaltotheforward-linkperformance,althoughthestatisticsoftheSIRsareslightlydifferent.翻译：一些近似的结论成立：最佳服务终端数量（从最大化平均吞吐量的角度看）是相干间隔的一半除以时延拓展，每个用户的吞吐量与相干时间无关，相干时间扩大两倍的影响是允许服务两倍数量的用户，反向信道和前向信道大致相同，尽管信干比有略微差别。3.5Fig.5showsthecumulativedistributionforthenetreversecapacityperterminal(14)forreusefactorsofone,three,andseven.LargerreusefactorsarebeneficialwhentheSIRislow,thelogarithmisinitslinearregion,andcapacitygainsduetothelargeincreaseinSIRmorethanoffsetthelossduetolessaggressivefrequencyreusewhichisassociatedwithareductionintheactualbandwidththateachcellutilizes.翻译：图5显示的是，复用因子为1,3,7时，每个用户的净反向（链路）容量（公式14）的累积分布。当信干比较小时，复用因子越大越好。对数函数在其线性区间内，容量增益是由于信干比的增加可以抵消相比于复用因子较小的小区实际带宽的减少。Figure2fig.5intheessay3.6AsshowninFig.1,wedenotethecomplexpropagationcoefficientbetweenthemthbasestationantennainthejthcell,andthekthterminalinthe?-thcellinthenthsubcarrierbygnmjkwhich,inturn,isequaltoacomplexfastfadingfactortimesanamplitudefactorthataccountsforgeometricattenuationandshadowfading,翻译：如图1所示，将在第j个小区的第m个基站天线到第l个小区的第k个用户在第n个子载波上的复传播系数gnmjk,等于复快衰落乘以表示几何衰落和阴影衰落的幅度因子。4.Content4.1whatismassiveMIMO？Thisisatransmissionpointequippedwithaverylargenumberofantennasthatsimultaneouslyservemultipleusers.大规模输入输出系统是一个具有大量天线并且能同时服务于多用户的传输系统。Figure3massivemimo4.2whatispilotcontamination？PilotcontaminationsimplymeansthattheestimationsofthechannelsbetweenoneBSanditsownusersarecontaminatedbythechannelsbetweenthatBSandtheusersoftheothercells.4.3ThereasonofPilotContaminationReuseofnon-orthogonaltrainingsequencesacrosscellsinamulti-cellmassiveMIMOsystemsduetolimitedcoherencetime.Hardwareimpairmentsduetoin-bandandout-of-bounddistortionsthatinterferewithtrainingsignals.Non-reciprocaltransceiversduetointernalclockstructuresoftheratiofrequencychain.4.4SystemModelOfMassiveMIMO4.4.1ScenarioWeconsiderthescenarioofLhexagonalcellularcells.thebasestationisequippedwithMantennasatthecenterofcellandKsingle-antennausersaredistributeduniformlyoverthecell,andM??K.Figure4ScenarioOfMassiveMIMO4.4.2UplinktransmissionThereceivedsignalsatthejthBScanberepresentedastheestimateforthepropagationmatrixThebasestationprocessesitsreceivedsignalbymultiplyingitbythetheconjugate-transposeofthechannelestimate,yields4.4.3UplinkCapacityAsMgrowswithoutlimit,ThekthcomponentoftheprocessedsignalbecomesSINRbecomescapacitybecomes