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：研究了一种双自可持续可重构智能表面（RISs）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可持续传输。目标是最小化基站（BS）的发射功率，同时保证用户的服务质量（QoS）要求并满足RIS的功耗需求。采用基于惩罚方法和逐次凸近似（SCA）的块坐标下降（BCD）算法，交替优化基站的主动波束成形、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，所提出的双自可持续RIS系统在基站处的所需功耗显著降低。