Simultaneously Transmitting and Reflecting Surface (STARS) for Terahertz Communications

A simultaneously transmitting and reflecting surface (STARS) aided terahertz (THz) communication system is proposed. novel power consumption model proposed that depends on the type resolution of STARS elements. The spectral efficiency (SE) energy (EE) are maximized in both narrowband wideband THz systems by jointly optimizing hybrid beamforming at base station (BS) passive STARS. 1) For systems, independent phase-shift STARSs investigated first. resulting complex joint optimization problem decoupled into a series subproblems using penalty dual decomposition. Low-complexity element- wise algorithms to optimize analog BS algorithm then extended case coupled 2) spatial effect leads significant performance degradation due beam split issue. To address this, true time delayers (TTDs) introduced conventional structure for facilitating beamforming. An iterative based quasi-Newton method design coefficients TTDs. Finally, our numerical results confirm superiority over reconfigurable intelligent (RIS). It also revealed i) there only slight loss terms SE EE caused phase shifts ii) achieves comparable much higher compared with full-digital but not where TTD-based required mitigating split.