To achieve the expected attractive potential of massive multiple-input multiple-output (MIMO), accurate match between the receiver and the actual channel is necessary. Due to the channel aging, this kind of mismatch appears in the vast majority of practical propagations. Consequently, the impact of channel aging for massive MIMO is investigated in this study. The authors first propose an equivalent estimated channel model by considering the inevitable time-varying nature of channels in realistic mobile communications. Then, they obtain the achievable uplink rate based on the proposed equivalent channel models. In particular, the closed-form expression of the asymptotic uplink rate is derived. Different from the existing works, this study considers the joint multi-cell minimum-mean-squared-error (MMSE) channel estimator and MMSE receiver for massive MIMO systems over aging channels. Through the simulation, it demonstrates that adopting massive MIMO can compensate for the performance loss caused by channel aging. In addition, this pstudy gives some insights into the system design: to achieve the best performance, system with higher-mobility terminals should be operated with more pilot resources, and it can support more users, moreover, the optimal number of users supported in a cell is less than half of the coherence time interval.

中文翻译：

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信道老化下的多小区多用户大规模MIMO频谱效率分析

为了实现大规模多输入多输出（MIMO）的预期诱人潜力，必须在接收器和实际信道之间进行精确匹配。由于信道老化，这种不匹配出现在绝大多数实际传播中。因此，本研究研究了信道老化对大规模MIMO的影响。作者首先考虑现实移动通信中不可避免的时变性质，提出了一个等效的估计信道模型。然后，他们根据提出的等效信道模型获得可实现的上行链路速率。特别地，得出渐近上行链路速率的闭合形式的表达式。与现有作品不同，这项研究考虑了针对老化信道上的大规模MIMO系统的联合多小区最小均方误差（MMSE）信道估计器和MMSE接收器。通过仿真表明，采用大规模MIMO可以弥补信道老化导致的性能损失。此外，本篇论文还对系统设计提供了一些见解：为了实现最佳性能，具有更高移动性的终端的系统应使用更多的导频资源进行操作，并且它可以支持更多的用户，此外，在一个终端中支持的最佳用户数。单元小于相干时间间隔的一半。