冀笑伟 李莉 魏爽 张铭

摘  要： 大规模多输入多输出（MIMO）系统中，大型天线阵列之间的强天线相关性会导致系统性能降低. 针对下行链路场景，提出基于最大比传输预编码的联合天线分组和天线选择算法，把大规模天线阵列划分为若干组，在每组中基于信道矩阵最大列范数选择天线，构造所选天线与接收天线间的信道矩阵，并计算对应的预编码矩阵.建立能效模型，分析联合天线分组和天线选择算法对系统能效的影响. 仿真结果表明，在基站天线数为200、发射功率为10 dB、天线相关因子为0.8的假设下，当分组数为24时，与最大范数天线选择算法相比，该算法使系统能效提高了约24.4%.

关键词： 大规模多输入多输出（MIMO）; 最大比传输预编码; 天线分组; 天线选择; 能效

中图分类号： TN 911.7     文献标志码： A     文章编号： 1000-5137（2021）01-0062-07

Abstract： In massive MIMO systems，the strong antenna correlation among large antenna arrays would lead to system performance degradation. In this paper a joint antenna grouping and antenna selection algorithm based on maximum ratio transmission precoding was proposed in regard to the downlink scenario in which the large-scale antenna array was divided into several groups. In each group，the antenna was selected based on the maximum column norm of the channel matrix. The channel matrix between the selected antenna and the receiving antenna was constructed，and the corresponding precoding matrix was calculated. Finally，an energy efficiency model was established to analyse the influence of both joint antenna grouping and antenna selection algorithm on energy efficiency of the system. The simulation results showed that under the assumption that the number of base station antennas was 200，the transmission power was 10 dB，and the antenna correlation factor was 0.8，when the number of packets was 24，comparing with the maximum norm antenna selection algorithm，the proposed algorithm was able to improve the system energy efficiency nearly by 24.4%.

Key words： massive multiple input multiple output（MIMO）; maximum ratio transmission precoding; antenna grouping; antenna selection; energy efficiency

0  引 言

近年來，大规模多入多出（MIMO）技术成为第五代通信网络中最有前途的技术之一，具有超大规模天线阵列的MIMO系统能够获得较高的吞吐量.然而，在大规模MIMO系统中，总功率消耗与发射天线的数量成正比，考虑到经济和可持续发展问题，能效已经成为绿色通信系统设计的重要指标.为了保证大规模MIMO系统吞吐量的优势，同时避免大规模天线阵列高成本、高功耗的问题，天线选择技术应运而生[1].

LI等[2]推导了基于最大比传输（maximum ratio transmission，MRT）预编码的下行速率和闭式容量下限，并建立以能效最大化为目标的优化模型，推导出固定发射功率下，最大化能效的最优发射天线数目……