Wireless communications empowered by Reconfigurable Intelligent (meta)Surfaces (RISs) are recently gaining remarkable research attention due to the increased system design flexibility offered by RISs for diverse functionalities. In this paper, we consider a Multiple Input Multiple Output (MIMO) physical layer security system with multiple data streams including one legitimate and one eavesdropping passive RISs, with the former being transparent to the eavesdropper and the latter's presence being unknown at the legitimate link. We first focus on the eavesdropping subsystem and present a joint design framework for the eavesdropper's combining vector and the reflection coefficients of the eavesdropping RIS. Then, focusing on the secrecy rate maximization, we propose a physical layer security scheme that jointly designs the legitimate precoding vector and the Artificial Noise (AN) covariance matrix, as well as the legitimate combining vector and the reflection coefficients of the legitimate RIS. Our simulation results reveal that, in the absence of a legitimate RIS, transceiver spatial filtering and AN are incapable of offering nonzero secrecy rates, even for eavesdropping RISs with small numbers of elements. However, when a L-element legitimate RIS is deployed, confidential communication can be safeguarded against cases with even more than a 5L-element eavesdropping RIS.
Two-Stage Refinement Sparse Channel Estimation for Reconfigurable Intelligent Metasurface Antenna (RIMSA) Massive MIMO
School of Information and Communications Engineering, Xi’an Jiaotong University（西安交通大学信息与通信工程学院）；School of Computer Science & Technology, Xi’an University of Posts & Telecommunications（西安邮电大学计算机科学与技术学院）
Are Stacked Intelligent Metasurfaces (SIMs) Better than Single-layer Reconfigurable Intelligent Surfaces (RISs) for Wideband Multi-user MIMO Communication Systems?
Anti-Jamming Sensing with Distributed Reconfigurable Intelligent Metasurface Antennas
School of Information and Communications Engineering, Xi’an Jiaotong University（信息与通信工程学院，西安交通大学）；Ministry of Education Key Laboratory for Intelligent Networks and Network Security, Xi’an Jiaotong University（教育部智能网络与网络安全重点实验室，西安交通大学）
