This paper focuses on multi-user downlink signal transmission in a wireless system aided by multiple reconfigurable intelligent surfaces (RISs). In such a multi-RIS, multi-user, multi-antenna scenario, determining a set of RIS phase shifts to maximize the sum throughput becomes intractable. Hence, we propose a novel scheme that can substantially simplify the optimization of passive beamforming. By opportunistically selecting a user with the best channel condition as the only active transmitter in the system, it degrades to single-user passive beamforming, where two methods, i.e., joint optimization based on the semidefinite relaxation approach and alternating optimization, are applicable. The superiority of the proposed scheme is demonstrated through Monte-Carlo simulations.
翻译:本文侧重于多用户下行链路信号传输的无线系统中的多用户下行链路信号传输,由多可重新配置的智能表面(RIS)协助。在这样的多RIS、多用户、多天文情景中,确定一套RIS阶段转移以最大限度地实现总吞吐量变得棘手。因此,我们提出了一个新方案,可以大大简化被动波束的优化。通过机会选择一个拥有最佳频道条件的用户作为系统中唯一活跃发射机,它降解为单一用户被动波束,其中适用两种方法,即基于半确定性放松办法的联合优化和交替优化。通过蒙特-卡尔洛模拟展示了拟议方案的优越性。</s>