A double self-sustainable reconfigurable intelligent surfaces (RISs) assisted multi-user multiple input multiple output (MIMO) system is investigated. Two RISs are equipped with energy harvesting circuit to achieve self-sustainable transmission. The aim is to minimize the transmission power at the base station (BS), while guaranteeing the quality of service (QoS) requirements of the users and meeting the power consumption requirements of the RISs. A block coordinate descent (BCD) algorithm based on the penalty-based method and successive convex approximation (SCA) is employed to alternatively optimize the active beamforming at the BS and the phase shifts, as well as amplitude coefficients of two RISs. Simulation results show that the required power consumption at the BS for the proposed double self-sustainable RISs system is significantly reduced compared to conventional RIS systems.

翻译：本文研究了一种双自持续可重构智能表面（RIS）辅助的多用户多输入多输出（MIMO）系统。两个RIS均配备能量采集电路以实现自持续传输。目标是基站在保证用户服务质量（QoS）需求并满足RIS功耗要求的同时，最小化其传输功率。采用基于惩罚方法和逐次凸近似（SCA）的块坐标下降（BCD）算法，交替优化基站的有源波束赋形、两个RIS的相位偏移及幅度系数。仿真结果表明，与传统RIS系统相比，所提出的双自持续RIS系统所需基站功耗显著降低。