Hybrid Precoding Algorithm for Millimeter-Wave Massive MIMO Systems with Subconnection Structures
Hybrid Precoding Algorithm for Millimeter-Wave Massive MIMO Systems with Subconnection Structures
复制标题
具有子连接结构的毫米波大规模MIMO系统的混合预编码算法
DOI：
10.1155/2021/5532939
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发表时间：
2021-06-10
影响因子：
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通讯作者：
Zhao, Feng
中科院分区：
文献类型：
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作者：
Zhang, Xue;Zhao, Feng
在毫米波大规模MIMO系统中，传统的数字预编码由于射频链的高成本和高能耗而难以实现。数字预编码和模拟预编码相结合的混合预编码不仅成功地解决了这个问题，而且有效地提高了系统的性能。然而，由于模拟域中移相器引入的恒定模式约束，难以直接求解混合预编码。有一种解决方案是将总体优化问题分为两个阶段来求解，即先固定数字预编码矩阵，再求解模拟预编码矩阵，然后根据得到的模拟预编码矩阵对数字预编码矩阵进行优化。本文针对子连接结构提出了一种高能效的混合预编码方案。在第一阶段，优化问题可以分解成一系列的子问题，通过独立的子矩阵结构的模拟预编码矩阵。在得到优化的模拟预编码矩阵后，利用最小平均误差（MMSE）算法求解数字预编码矩阵。最后，对数字预编码矩阵进行归一化处理，使其满足约束条件。仿真结果表明，该算法的性能接近于基于子连接结构的全数字预编码算法，优于现有算法。此外，本文还对该算法在不完全信道状态信息下的性能进行了仿真分析。仿真结果表明，当信道状态信息估计精度为0.8时，该算法的频谱效率已经可以保持在较好的水平。
In mmWave massive MIMO systems, traditional digital precoding is difficult to be implemented because of the high cost and energy consumption of RF chains. Fortunately, the hybrid precoding which combines digital precoding and analog precoding not only solves this problem successfully, but also improves the performance of the system effectively. However, due to the constant mode constraint introduced by the phase shifter in the analog domain, it is difficult to solve the hybrid precoding directly. There is a solution which divides the total optimization problem into two stages to solve, that is, first fix the digital precoding matrix, solve the analog precoding matrix, and then optimize the digital precoding matrix according to the obtained analog precoding matrix. In this paper, a high energy-efficient hybrid precoding scheme is proposed for the subconnection structure. In the first stage, the optimization problem can be decomposed into a series of subproblems by means of the independent submatrix structure of the analog precoding matrix. When the optimized analog precoding matrix is obtained, the digital precoding matrix can be solved by the minimum mean error (MMSE). Finally, the digital precoding matrix is normalized to satisfy the constraint conditions. The simulation results demonstrate that the performance of the proposed algorithm is close to that of fully digital precoding based on subconnection structure and better than that of the existing algorithms. In addition, this paper presents the simulation analysis of the algorithm performance under imperfect channel state information. Simulation results show that when the estimation accuracy of channel state information is 0.8, the spectral efficiency of the proposed algorithm can already be maintained at a good level.