STARS for Spectral Efficiency in Wideband Terahertz Communications

Abstract

A wideband simultaneously transmitting and reflecting surface (STARS) aided terahertz (THz) communication system is proposed. The spatial wideband effect at the base station (BS) and STARS leads to significant performance degradation due to the beam split issue. To address this, true time delayers (TTDs) are introduced into the conventional hybrid beamforming structure for facilitating wideband beamforming. The hybrid beamforming at the BS and the passive beamforming at the STARS are jointly designed to maximize the spectral efficiency of the proposed system. A double-loop iterative algorithm based on penalty dual decomposition is proposed to solve the resulting optimization problem. Finally, the numerical results confirm the effectiveness of exploiting STARS in wideband THz systems.