数字模拟混合预编码可以用较少的射频逼近全数字预编码的性能,可以用来解决毫米波大规模MIMO系统中由于射频链路过多造成的硬件损耗和校准问题.为解决传统混合预编码结构难以实现的缺点,该文的混合预编码研究基于一种简单的固定子连接结构.推导了系统可达速率最大,模拟预编码矩阵应满足的条件,从而将混合预编码矩阵设计问题转化为优化问题.采用鸟群算法(BSA)解决此优化问题,求得最优的预编码矩阵.针对模拟移相器分辨率有限的情况,提出一种直接量化的解决方案和一种基于改进的离散BSA的解决方案.仿真结果表明,所提算法能够基于简单结构实现较好的性能;移相器分辨率有限情况下,所提的两种解决方案都是有效的,且基于离散BSA的方案在分辨率较低时性能更优.%The digital and analogue Hybrid Precoding (HP) is able to keep the performance close to that of the fully digital precoding with reduced Radio Frequency (RF) chains. In a millimeter wave massive MIMO system, the HP can be used to overcome the undesired hardware cost and calibration workload caused by the excessive RFs. Considering that the conventional HP structure is not practical, the research is based on a simple fixed sub-connection structure. The condition that the analogue precoding matrix should meet to maximize the sum achievable rate is deduced, so that the design of the analogue precoding matrix is transformed into an optimization problem. The optimal analogue precoding matrix is obtained by using Bird Swarm Algorithm (BSA). Considering that finite resolution phase shifters are used, a straightforward quantization solution and an improved discrete BSA based solution are proposed. The simulation results show that the proposed algorithm can achieve good performance based on simple structure. While using finite resolution phase shifter, both of the proposed solutions are effective, furthermore, the solution based on the discrete BSA can get better performance while the resolution is low.
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