Due to its inherent ability in reducing hardware cost and power consumption while maintaining high system capacity, hybrid precoding is deemed as one of the key technologies in the upcoming 5G/6G millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) systems. However, it is challenging to design high performance hybrid precoders/combiners with low computational complexity. In this paper, based on the singular value decomposition (SVD) technique and the concept of equivalent channel, joint hybrid precoding strategies with high spectral-efficiency and low complexity are proposed for both single-user and multi-user massive MIMO systems. Specifically, for single-user massive MIMO scenarios, after transforming the design of hybrid beamforming into the problem of maximizing the square of sum eigenvalues for an equivalent channel, a two-stage successive method is conceived to design the analog precoder and combiner jointly, and the corresponding equivalent channel is constructed. Then, the digital precoding and combining operations are realized directly by applying the SVD technique to the matrix of equivalent channel. Meanwhile, the hybrid precoding strategy is extended to the multi-user scenario for achieving high performance resultant from multi-user diversity. Extensive simulations are conducted to verify the effectiveness of the precoding/combing schemes. The results show that our proposed schemes can achieve superior performance with lower complexity compared to the existing ones.

中文翻译：

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大规模MIMO系统基于等效信道的联合混合预编码/组合方案


由于混合预编码具有在保持高系统容量的同时降低硬件成本和功耗的固有能力，因此被认为是即将到来的5G/6G毫米波（mmWave）大规模多输入多输出（MIMO）的关键技术之一系统。然而，设计具有低计算复杂度的高性能混合预编码器/组合器具有挑战性。本文基于奇异值分解（SVD）技术和等效信道的概念，针对单用户和多用户大规模MIMO系统提出了高频谱效率和低复杂度的联合混合预编码策略。具体来说，针对单用户大规模MIMO场景，将混合波束成形的设计转化为最大化等效信道的特征值和平方问题后，提出两阶段连续方法联合设计模拟预编码器和组合器，并构建相应的等效通道。然后，将SVD技术应用于等效信道矩阵，直接实现数字预编码和合并操作。同时，将混合预编码策略扩展到多用户场景，以实现多用户分集带来的高性能。进行了大量的模拟来验证预编码/组合方案的有效性。结果表明，与现有方案相比，我们提出的方案可以以更低的复杂度实现卓越的性能。