Hybrid precoding, combining the digital and analogue precoding, is a key enabler to reach a compromise between system performance and hardware complexity in millimetre wave (mmWave) massive multiple-input multiple-output (MIMO) systems. Most previous studies on hybrid precoding considered narrowband channels. However, mmWave systems are expected to operate on wideband channels with frequency selectivity. In this study, the authors focus on the hybrid precoding design in mmWave massive MIMO systems using orthogonal frequency division multiplexing (OFDM). By transforming the hybrid precoding problem into a series of sub-problems, they propose a low-complexity algorithm to design the digital precoder and analogue precoder alternately. In particular, a phase pursuit method is introduced to seek this solution of analogue precoding matrix with the constant amplitude constraint. Simulation results and complexity evaluations reveal that the proposed algorithm can obtain better performance and lower complexity than some existing solutions in mmWave OFDM systems.

中文翻译：

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宽带毫米波大规模MIMO系统的替代混合预编码算法

混合预编码结合了数字和模拟预编码，是在毫米波（mmWave）大规模多输入多输出（MIMO）系统中实现系统性能和硬件复杂性之间折衷的关键推动力。以前有关混合预编码的大多数研究都考虑了窄带信道。但是，毫米波系统有望在具有频率选择性的宽带信道上运行。在这项研究中，作者专注于使用正交频分复用（OFDM）的mmWave大规模MIMO系统中的混合预编码设计。通过将混合预编码问题转化为一系列子问题，他们提出了一种低复杂度算法来交替设计数字预编码器和模拟预编码器。尤其是，引入了一种相位追踪方法，以寻求具有恒定幅度约束的模拟预编码矩阵的这种解决方案。仿真结果和复杂度评估表明，与毫米波OFDM系统中的某些现有解决方案相比，该算法可以获得更好的性能和更低的复杂度。