大规模MIMO系统研究进展
Overview of Massive MIMO System

随着线通信技术的快速发展和智能手机的迅速普及，人们对数据传输速率提出了更高的需求。为进一步提高数据传输速率，通过增加基站天线数目构建大规模MIMO系统，是一种高效而相对便捷的方式。大规模MIMO系统能深度发掘空间维的自由度，使得基站能够利用同一时频资源服务于多个用户。本文探讨了大规模MIMO系统的导频污染问题及解决方案、适用于大规模MIMO系统的信道模型以及低复杂度的传输技术与实现方法三项关键技术。与现有MIMO系统相比，大规模MIMO系统能显著提高频谱效率、能量效率和系统的鲁棒性能。作为第五代移动通信（5G）最具潜力的研究内容之一，大规模MIMO线通信技术已引起国内外的广泛关注，但相关研究工作尚处在起步阶段，还有大量的技术难点需要进一步突破。
With the rapid development of wireless communications and the popularization of smartphones, higher data rate of the service is required. The demand can be efficiently and conveniently satisfied by increasing the number of antennas at base station (BS), thus resulting in a massive MIMO system. The massive MIMO system can exploit the spatial degree of freedom, and therefore BS is enabled to simultaneously serve several user equipments (UE) with the same temporal and frequency resource. Three key techniques are presented in the massive MIMO system, including the pilot contamination issue and the corresponding solutions, the theoretical and practical channel model that fits for the massive MIMO system, and the low complexity transmission and implement methods. Compared with the existing MIMO system, the massive MIMO system can distinctively increase the spectral efficiency, the energy efficiency, and the system robustness. As one of the most promising topics on the fifth generation (5G) of wireless communication systems, the massive MIMO system has attracted the extensive attention worldwide. Nevertheless, the research of massive MIMO systems is still at its early stage, with a lot of technical problems to be solved.