Millimeter-wave (mm-wave) communication is a key technology for future wireless networks. To combat significant path loss and exploit the abundant mm-wave spectrum, effective beamforming is crucial. Nevertheless, conventional fully digital beamforming techniques are inapplicable, as they demand a separate radio frequency (RF) chain for each antenna element, which is costly and consumes too much energy. Hybrid beamforming is a cost-effective alternative, which can significantly reduce the hardware cost and power consumption by employing a small number of RF chains. This paper presents a holistic view on hybrid beamforming for 5G and beyond mm-wave systems, based on a new taxonomy for different hardware structures. We take a pragmatic approach and compare different proposals from three key aspects: 1) hardware efficiency, i.e., the required hardware components; 2) computational efficiency of the associated beamforming algorithm; and 3) achievable spectral efficiency, a main performance indicator. Through systematic comparisons, the interplay and trade-off among these three design aspects are demonstrated, and promising candidates for hybrid beamforming in future wireless networks are identified.

中文翻译：

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适用于5G和超越毫米波系统的混合波束成形：整体视图

毫米波（mm-wave）通信是未来无线网络的一项关键技术。为了克服重大的路径损耗并利用丰富的毫米波频谱，有效的波束成形至关重要。然而，常规的全数字波束成形技术是不适用的，因为它们要求每个天线元件使用单独的射频（RF）链，这既昂贵又消耗太多能量。混合波束成形是一种经济高效的替代方案，它可以通过使用少量RF链来显着降低硬件成本和功耗。本文基于针对不同硬件结构的新分类法，针对5G和毫米波系统以外的混合波束成形提出了整体观点。我们采取务实的方法，并从三个关键方面比较不同的建议：1）硬件效率，即 所需的硬件组件；2）相关波束成形算法的计算效率；3）可达到的频谱效率是主要性能指标。通过系统比较，证明了这三个设计方面之间的相互作用和折衷，并确定了未来无线网络中混合波束成形的有希望的候选者。