Passive Beamforming and Information Transfer Design for Reconfigurable Intelligent Surfaces Aided Multiuser MIMO Systems
Passive Beamforming and Information Transfer Design for Reconfigurable Intelligent Surfaces Aided Multiuser MIMO Systems
复制标题
可重构智能表面辅助多用户 MIMO 系统的无源波束成形和信息传输设计
DOI：
10.1109/jsac.2020.3000811
复制
发表时间：
2020-08-01
影响因子：
16.4
通讯作者：
Kuai, Xiaoyan
中科院分区：
文献类型：
--
作者：
Yan, Wenjing;Yuan, Xiaojun;Kuai, Xiaoyan
本文研究了借助可重构智能表面（RIS）的多用户多输入多输出（Mu-MIMO）系统的无源波束成形和信息传输（PBIT）技术，其中RIS通过无源波束成形（P-BF）增强主通信，同时通过开关反射调制传递附加信息（其中RIS信息由每个反射元件的开/关状态携带）。对于 P-BF 设计，我们建议最大化 RIS 辅助 Mu-MIMO 信道可实现的用户总速率，并将问题表述为两步随机程序。开发了基于样本平均近似 (SAA) 的迭代算法，用于所考虑方案的高效 P-BF 设计。为了在复杂性和性能之间取得平衡，我们进一步提出了一种简化的 P-BF 算法，将随机程序近似为确定性交替优化问题。对于接收器设计，接收器处的信号检测是双线性估计问题，因为RIS信息被乘法调制到反射元件的反射信号上。为了解决这个双线性估计问题，我们开发了一种涡轮消息传递（TMP）算法，其中与问题相关的因子图被分为两个模块：一个用于估计用户信号，另一个用于估计每个RIS元件的开关状态。这两个模块迭代执行以产生接近最优的低复杂度解决方案。此外，我们利用单 RIS 和多 RIS 系统模型之间的相似性，将 Mu-MIMO PBIT 方案的设计从单 RIS 扩展到多 RIS。提供了大量的仿真结果来证明我们的 P-BF 和接收器设计的优势。
This paper investigates the passive beamforming and information transfer (PBIT) technique for multiuser multiple-input multiple-output (Mu-MIMO) systems with the aid of reconfigurable intelligent surfaces (RISs), where the RISs enhance the primary communication via passive beamforming (P-BF) and at the same time deliver additional information by the on-off reflecting modulation (in which the RIS information is carried by the on/off state of each reflecting element). For the P-BF design, we propose to maximize the achievable user sum rate of the RIS-aided Mu-MIMO channel and formulate the problem as a two-step stochastic program. A sample average approximation (SAA) based iterative algorithm is developed for the efficient P-BF design of the considered scheme. To strike a balance between complexity and performance, we further propose a simplified P-BF algorithm by approximating the stochastic program as a deterministic alternating optimization problem. For the receiver design, the signal detection at the receiver is a bilinear estimation problem since the RIS information is multiplicatively modulated onto the reflected signals of the reflecting elements. To solve this bilinear estimation problem, we develop a turbo message passing (TMP) algorithm in which the factor graph associated with the problem is divided into two modules: one for the estimation of the user signals and the other for the estimation of the on-off state of each RIS element. The two modules are executed iteratively to yield a near-optimal low-complexity solution. Furthermore, we extend the design of the Mu-MIMO PBIT scheme from single-RIS to multi-RIS, by leveraging the similarity between the single-RIS and multi-RIS system models. Extensive simulation results are provided to demonstrate the advantages of our P-BF and receiver designs.