Millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) systems allow for a data transmission rate of gigabits per second owing to the large bandwidth available in the mmWave spectrum and the antenna gains provided by the massive MIMO system. However, hybrid precoding with high complexity and low spectral efficiency cannot address the challenge of high cost and power consumption of RF chains of multi-user systems. In this paper, we propose a low-complexity hybrid precoding scheme for downlink multi-antenna multi-user mmWave massive MIMO systems, aiming to enhance the sum spectral efficiency (SSE) performance. We first extend the dimension of the analog precoding matrix into a square matrix and find the optimal analog combiner by selecting some of the discrete Fourier transform (DFT) bases, which enhances the equivalent baseband channel matrix gain. Then, we directly aggregate the channel gain through the equal gain transmission (EGT) method to ensure the frequency efficiency performance. Finally, we propose an improved BD scheme to design the digital precoder and combiner to reduce the inter-user interference. We consider both the mmWave channel and the Rayleigh channel to evaluate the performance of the proposed algorithm. The simulation results verify that the proposed scheme enjoys near-optimal achievable sum spectrum efficiency and BER performance in both the mmWave channel and Rayleigh channel and performs even better in Rayleigh channel than in the mmWave channel.

由于毫米波频谱中可用的大带宽和大规模 MIMO 系统提供的天线增益，毫米波 (mmWave) 大规模多输入多输出 (MIMO) 系统允许每秒千兆位的数据传输速率。然而，高复杂度和低频谱效率的混合预编码无法解决多用户系统射频链的高成本和高功耗挑战。在本文中，我们提出了一种用于下行链路多天线多用户毫米波大规模 MIMO 系统的低复杂度混合预编码方案，旨在提高总频谱效率 (SSE) 性能。我们首先将模拟预编码矩阵的维度扩展为方阵，并通过选择一些离散傅里叶变换 (DFT) 基来找到最佳模拟组合器，这增强了等效基带信道矩阵增益。然后，我们通过等增益传输（EGT）方法直接聚合信道增益，以确保频率效率性能。最后，我们提出了一种改进的BD方案来设计数字预编码器和组合器，以减少用户间干扰。我们同时考虑毫米波通道和瑞利通道来评估所提出算法的性能。仿真结果验证了所提出的方案在毫米波通道和瑞利通道中均具有接近最佳的可实现总频谱效率和误码率性能，并且在瑞利通道中的性能甚至优于毫米波通道。我们提出了一种改进的BD方案来设计数字预编码器和组合器以减少用户间干扰。我们同时考虑毫米波通道和瑞利通道来评估所提出算法的性能。仿真结果验证了所提出的方案在毫米波通道和瑞利通道中均具有接近最佳的可实现总频谱效率和误码率性能，并且在瑞利通道中的性能甚至优于毫米波通道。我们提出了一种改进的BD方案来设计数字预编码器和组合器以减少用户间干扰。我们同时考虑毫米波通道和瑞利通道来评估所提出算法的性能。仿真结果验证了所提出的方案在毫米波通道和瑞利通道中均具有接近最佳的可实现总频谱效率和误码率性能，并且在瑞利通道中的性能甚至优于毫米波通道。