Benefiting from tens of GHz of bandwidth, terahertz (THz) communications has become a promising technology for future 6G networks. However, the conventional hybrid beamforming architecture based on frequency-independent phase-shifters is not able to cope with the beam split effect (BSE) in THz massive multiple-input multiple-output (MIMO) systems. Despite some work introducing the frequency-dependent phase shifts via the time delay network to mitigate the beam splitting in THz wideband communications, the corresponding issue in reconfigurable intelligent surface (RIS)-aided communications has not been well investigated. In this paper, the BSE in THz massive MIMO is quantified by analyzing the array gain loss. A new beamforming architecture has been proposed to mitigate this effect under RIS-aided communications scenarios. Simulations are performed to evaluate the effectiveness of the proposed system architecture in combating the array gain loss.

翻译：受益于数十GHz的带宽，太赫兹通信已成为未来6G网络的一项有前景技术。然而，基于频率无关移相器的传统混合波束赋形架构无法应对太赫兹大规模多输入多输出系统中的波束分裂效应。尽管已有研究通过时延网络引入频率相关相移来缓解太赫兹宽带通信中的波束分裂问题，但在可重构智能表面辅助通信场景中的相应问题尚未得到充分研究。本文通过分析阵列增益损失对太赫兹大规模MIMO中的BSE进行了量化，并提出了一种新的波束赋形架构以在RIS辅助通信场景下缓解该效应。仿真实验验证了所提系统架构在对抗阵列增益损失方面的有效性。