Beamforming Design for RIS-Aided THz Wideband Communication Systems

TL;DR

This paper addresses the beam split effect in THz wideband RIS-aided MIMO systems, proposing a new beamforming architecture to mitigate array gain loss caused by frequency-dependent beamforming issues.

Contribution

It introduces a novel beamforming architecture specifically designed for RIS-aided THz systems to combat the beam split effect, which was not previously well studied.

Findings

The proposed architecture effectively mitigates array gain loss.

Simulations show improved beamforming performance in THz wideband scenarios.

The method outperforms conventional hybrid beamforming in mitigating BSE.

Abstract

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.