Analog/digital hybrid beamforming is considered as a key enabling multiple antenna technology for implementing millimeter wave (mmWave) multiple-input multiple-output (MIMO) communications since it can reduce the number of costly and power-hungry radio frequency (RF) chains while still providing for spatial multiplexing. In this paper, we introduce a novel hybrid beamforming architecture with dynamic antenna subarrays and hardware-efficient low-resolution phase shifters (PSs) for a wideband mmWave MIMO orthogonal frequency division multiplexing (MIMO-OFDM) system. By dynamically connecting each RF chain to a non-overlapping antenna subarray via a switch network and PSs, multiple-antenna diversity can be exploited to mitigate the performance loss due to the employment of practical low-resolution PSs. For this dynamic hybrid beamforming architecture, we jointly design the hybrid precoder and combiner to maximize the average spectral efficiency of the mmWave MIMO-OFDM system. In particular, the spectral efficiency maximization problem is first converted to a mean square error (MSE) minimization problem. Then, an efficient iterative hybrid beamformer algorithm is developed based on classical block coordination descent (BCD) methods. An analysis of the convergence and complexity of the proposed algorithm is also provided. Extensive simulation results demonstrate the superiority of the proposed hybrid beamforming algorithm with dynamic subarrays and low-resolution PSs.

中文翻译：

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用于宽带毫米波 MIMO-OFDM 系统的具有低分辨率 PS 的动态混合波束成形

模拟/数字混合波束成形被认为是实现毫米波 (mmWave) 多输入多输出 (MIMO) 通信的关键启用多天线技术，因为它可以减少昂贵且耗电的射频 (RF) 链的数量，同时仍然提供空间复用。在本文中，我们为宽带毫米波 MIMO 正交频分复用 (MIMO-OFDM) 系统引入了一种具有动态天线子阵列和硬件高效低分辨率移相器 (PS) 的新型混合波束成形架构。通过通过交换网络和 PS 将每个 RF 链动态连接到非重叠天线子阵列，可以利用多天线分集来减轻由于使用实用的低分辨率 PS 而造成的性能损失。对于这种动态混合波束成形架构，我们联合设计了混合预编码器和组合器，以最大化毫米波 MIMO-OFDM 系统的平均频谱效率。特别是，频谱效率最大化问题首先被转换为均方误差 (MSE) 最小化问题。然后，基于经典块协调下降 (BCD) 方法开发了一种高效的迭代混合波束形成器算法。还提供了对所提出算法的收敛性和复杂性的分析。广泛的仿真结果证明了所提出的混合波束成形算法与动态子阵列和低分辨率 PS 的优越性。频谱效率最大化问题首先转换为均方误差 (MSE) 最小化问题。然后，基于经典块协调下降 (BCD) 方法开发了一种高效的迭代混合波束形成器算法。还提供了对所提出算法的收敛性和复杂性的分析。广泛的仿真结果证明了所提出的混合波束成形算法与动态子阵列和低分辨率 PS 的优越性。频谱效率最大化问题首先转换为均方误差 (MSE) 最小化问题。然后，基于经典块协调下降 (BCD) 方法开发了一种高效的迭代混合波束形成器算法。还提供了对所提出算法的收敛性和复杂性的分析。广泛的仿真结果证明了所提出的混合波束成形算法与动态子阵列和低分辨率 PS 的优越性。