时间相关信道下分布式大规模MIMO系统频谱效率分析

为了分析时变信道特性对多用户分布式大规模MIMO系统的频谱效率性能影响，通过引入一阶高斯马尔科夫过程来建模时变信道，以时间相关性系数表征时变快慢程度。当系统采用最大比合并（MRC）接收和最大比发送（MRT）预编码方案时，借助于确定性等价原理以及Gamma分布随机变量的性质，推导出了含有信道时变信息的上行和下行频谱效率闭合表达式。同时，给出了当基站总发送天线数与用户个数之比趋于无穷大时，频谱效率的极限表达式。分析表明，频谱效率随时间相关系数减小而降低，但并不影响系统所获得的发射功率增益。数值仿真验证了所推导的频谱效率闭合表达式和极限值的有效性和精确性，并比较得出时变信道下分布式大规模MIMO比集中式大规模MIMO具有更好的性能。 

Analysis over Spectral Efficiency for Distributed Massive MIMO Systems with Temporally Correlated Channel

To analyze the impact of the time-variant channel for multiuser distributed massive multiple-input multiple-output (MIMO) system, the first order Gauss-Markov process was introduced to model the time-variant channel, where temporal correlation coefficient was adopted to characterize the degree of time-varying. Using the deterministic equivalent principles and the properties of random variable with Gamma distribution, we derived the closed-form expression of the uplink and downlink spectral efficiency including the temporal correlation coefficient in it, when the maximum ratio combining (MRC) detection and the maximum ratio transmission (MRT) precoding were employed. Meanwhile, the limiting performance of spectral efficiency was given when the ratio of the total number of antennas to the number of users goes to infinity, which indicates that the spectral efficiency decreases with temporal correlation coefficient without affecting the transmit power gain. Numerical simulations validate the accuracy of the proposed analytical expression of the spectral efficiency and shows that distributed massive MIMO outperforms centralized massive MIMO even with channel temporal correlation.