Title: Simultaneously Transmitting and Reflecting Surface (STARS) for Terahertz Communications Show Chinese title

Title: 同时发射和反射表面（STARS）用于太赫兹通信

Abstract: A simultaneously transmitting and reflecting surface (STARS) aided terahertz (THz) communication system is proposed. A novel power consumption model depending on the type and the resolution of individual elements is proposed for the STARS. Then, the system energy efficiency (EE) and spectral efficiency (SE) are maximized in both narrowband and wideband THz systems. 1) For the narrowband system, an iterative algorithm based on penalty dual decomposition is proposed to jointly optimize the hybrid beamforming at the base station (BS) and the independent phase-shift coefficients at the STARS. The proposed algorithm is then extended to the coupled phase-shift STARS. 2) For the wideband system, to eliminate the beam split effect, a time-delay (TD) network implemented by the true-time-delayers is applied in the hybrid beamforming structure. An iterative algorithm based on the quasi-Newton method is proposed to design the coefficients of the TD network. Finally, our numerical results reveal that i) there is a slight performance loss of EE and SE caused by coupled phase shifts of the STARS in both narrowband and wideband systems, and ii) the conventional hybrid beamforming achieved close performance of EE and SE to the full-digital one in the narrowband system, but not in the wideband system where the TD-based hybrid beamforming is more efficient. Show Chinese abstract

Abstract: 一种同时发射和反射表面（STARS）辅助的太赫兹（THz）通信系统被提出。 为STARS提出了一个依赖于单个元件类型和分辨率的新功耗模型。 然后，在窄带和宽带THz系统中最大化系统能效（EE）和频谱效率（SE）。 1）对于窄带系统，提出了一种基于惩罚对偶分解的迭代算法，以联合优化基站（BS）的混合波束成形和STARS的独立相移系数。 所提出的算法随后扩展到了耦合相移的STARS。 2）对于宽带系统，为了消除波束分裂效应，在混合波束成形结构中应用了一个由真时延器实现的时间延迟（TD）网络。 提出了一种基于拟牛顿法的迭代算法来设计TD网络的系数。 最后，我们的数值结果表明，i）在窄带和宽带系统中，STARS的耦合相移导致了EE和SE的轻微性能损失，ii）在窄带系统中，传统的混合波束成形实现了与全数字相近的EE和SE性能，但在宽带系统中，基于TD的混合波束成形更高效。