This paper investigates robust and secure multiuser multiple-input single-output (MISO) downlink communications assisted by a self-sustainable intelligent reflection surface (IRS), which can simultaneously reflect and harvest energy from the received signals. We study the joint design of beamformers at an access point (AP) and the phase shifts as well as the energy harvesting schedule at the IRS for maximizing the system sum-rate. The design is formulated as a non-convex optimization problem taking into account the wireless energy harvesting capability of IRS elements, secure communications, and the robustness against the impact of channel state information (CSI) imperfection. Subsequently, we propose a computationally-efficient iterative algorithm to obtain a suboptimal solution to the design problem. In each iteration, S-procedure and the successive convex approximation are adopted to handle the intermediate optimization problem. Our simulation results unveil that: 1) there is a non-trivial trade-off between the system sum-rate and the self-sustainability of the IRS; 2) the performance gain achieved by the proposed scheme is saturated with a large number of energy harvesting IRS elements; 3) an IRS equipped with small bit-resolution discrete phase shifters is sufficient to achieve a considerable system sum-rate of the ideal case with continuous phase shifts.
翻译:本文调查了由自可持续智能反射表面(IRS)协助的强大和安全的多用户多投入单产出(MISO)下链通信,该反射面可以同时反映和从收到的信号中获取能量。我们研究了进入点和阶段转移的光线设计以及IRS为尽量扩大系统总和而采用的能源采集时间表。设计是非碳化优化问题,其中考虑到IRS元素的无线能源采集能力、安全通信和对频道国家信息不完善的影响的稳健性。随后,我们提出了一种计算效率高的迭代算法,以获得设计问题的亚优度解决方案。在每次循环、S-程序及连续的convex近似处理中间优化问题中,我们模拟结果显示:(1) 系统总和与IRS的自我可持续性之间存在非三重交易;(2) 拟议的计划取得的业绩收益是饱和化的,拥有相当数量的离子系统离子系统离差分解阶段(IRS)实现相当高的离子流动阶段。