基站端无穷天线的非协作蜂窝无线通信-外文翻译

1、题目： Noncooperative Cellular Wireless withUnlimitedNumbers of Base Station1.Introduction of the essay1.1Essay:Noncooperative Cellular Wireless with UnlimitedNumbers of Base Station AntennasChinese translation:基站端无穷天线的非协作蜂窝无线通信1.2why to choose this essayThis essay are written by TL Marzetta who is fro

2、m Bell Labs,and it is cited by other articles many times.It yields a number of mathematically exact conclusions and points to a desirable direction towards which cellular wireless could evolve.Figure1 Introduction of the essay1.3 background of the essayKeywords:Pilot contamination（导频污染） ,Massive MIM

3、O system（大规模输入输出系统） ,Time-division duplex （时分复用）2.Words&ExpressionsWords&ExpressionsChinese translationscellular小区antenna天线base station基站time-division duplex （TDD ）时分复用frequency-division duplex（FDD ）频分复用reverse-link channel反向信道forward-link channel前向信道pilot导频pilot contamination导频污染channel-state infor

4、mation（CSI）信道估计linear precoder线性预编码fast fading快衰落log-normal shadow fading对数正态阴影衰落geometric attention几何衰落Words&ExpressionsChinese translationsinter-cellular interferencesignal-to-interference ratio（ SIR）pilot sequencereusethroughoutcapacityspectrum efficiencyenergy efficiencyconjugate-transposepropag

5、ation matrixzero-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.Translations3.1 In the limit of an infinite number of antennas a complete multi-cellular analysis, which accounts for inter-cellular interference and the overhead and errors associated with channel-state information

6、, yields a number of mathematically exact conclusions and points to a desirable direction towardswhich cellular wireless could evolve.分析：句子的主语为a complete multi-cellularanalysis ，谓语为 yields和 points to 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。3.2 In

7、particular the effects of uncorrelated noise and fast fading vanish, throughput and the number of terminals are independent of the size of the cells, spectral efficiency is independent of bandwidth, and the required transmitted energy per bit vanishes.分析：“are independent of ”本义为“不独立于” ，这里可以翻译为 “与 .

8、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。The only remaining impairment is inter-cellular interference caused by re-use of the pilot sequences in other cells (pilot contamination) which does not vanish with unlimited number of antennas.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）

9、不会随着天线数量增加而消失。3.3We consider a cellular system consisting of noncooperative hexagonal cells with frequency re-use of one, three, or seven, TDD operation, Orthogonal Frequency Division Multiplexing (OFDM), and base station arrays comprising M antennas where M , where each base station serves K single

10、-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。3.4Several approximate conclusions hold: the optimum number of terminals to serve (from the standpoint of maximizing the mean throughput) is equal to one-half of the duration of the co

11、herence interval divided by the delay-spread, the throughput per terminal is independent of the coherence time, the effect of doubling the coherence time is to permit twice as many terminals to be serviced, and the reverse-link performance is nearly identical to the forward-link performance, althoug

12、h the statistics of the SIRs are slightly different.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. 5 shows the cumulative distribution for the net reverse capacity per terminal (14) for reuse factors of one, three, and s

13、even. Larger reuse factors are beneficial when the SIR is low, the logarithm is in its linear region, and capacity gains due to the large increase in SIR more than offset the loss due to less aggressive frequency reuse which is associated with a reduction in the actual bandwidth that each cell utili

14、zes.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。Figure2 fig.5 in the essay3.6As shown in Fig. 1, we denote the complex propagation coefficient between the mth base station antenna in the jthcell,and the kth terminal in the ?-th

15、 cell in the nth subcarrier by gnmjk which, in turn, is equal to a complex fast fading factor times an amplitude factor that accounts for geo metric attenuation and shadow fading,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.Content4.1what is massive M

16、IMO？This is a transmission point equipped with a very large number of antennas thatsimultaneously serve multiple users.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。Figure3 massive mimo4.2 what is pilot contamination？Pilot contamination simply means that the estimations of the channels between one BS and its o

17、wn users are contaminated by the channels between that BS and the users of the other cells.4.3The reason of Pilot ContaminationReuse of non-orthogonal training sequences across cells in a multi-cell massive MIMO systems due to limited coherence time.Hardware impairments due to in-band and out-of-bou

18、nd distortions that interfere with training signals.Non-reciprocal transceivers due to internal clock structures of the ratio frequency chain.4.4System Model Of Massive MIMOWe consider the scenario of L hexagonal cellular cells.the base station is equipped with M antennas at the center of cell and K single-antenna users are distributeduniformly over the cell, and M ? K.Figure4 Scenario Of Massive MIMOThe received signals at the jth BS