Transmissive Reconfigurable Intelligent Surface Transmitter Empowered Cognitive RSMA Networks

Abstract

In this paper, a novel transmissive reconfigurable intelligent surface (TRIS) transceiver empowered integrated sensing and communications (ISAC) system is proposed for future multi-demand terminals. To address interference management, we implement rate-splitting multiple access (RSMA), where the common stream is independently designed for the sensing service. We introduce the sensing quality of service (QoS) criteria based on this structure and construct an optimization problem with the sensing QoS criteria as the objective function to optimize the sensing stream precoding matrix and the communication stream precoding matrix. Due to the coupling of optimization variables, the formulated problem is a non-convex optimization problem that cannot be solved directly. To tackle the abovementioned challenging problem, alternating optimization (AO) is utilized to decouple the optimization variables. Specifically, the problem is decoupled into three subproblems about the sensing stream precoding matrix, the communication stream precoding matrix, and the auxiliary variables, which is solved alternatively through AO until the convergence is reached. For solving the problem, successive convex approximation (SCA) is applied to deal with the sum-rate threshold constraints on communications, and difference-of-convex (DC) programming is utilized to solve rank-one non-convex constraints. Numerical simulation results verify the superiority of the proposed scheme in terms of improving the communication and sensing QoS.

User Selection for Simple Passive Beamforming in Multi-RIS-Aided Multi-User Communications

“…Based on the imperfect CSI assumption, a robust system sum-rate maximization strategy was proposed. Very recently, the authors of [27] proposed a transmissive RIS transmitter empowered cognitive radio network scheme to realize low-power, high-rate multi-stream transmissions.…”

“…In practical implementations, the communication between the feed antenna and the RIS occurs over a short distance, typically less than the Rayleigh distance [30]. To properly account for the unique characteristics arising from wave propagation in the near-field regime, a statistical model known as the non-uniform spherical wave-based channel model is adopted herein 2 [27]. Then, the near-field channel from the feed antenna to the RIS can be directly modeled as a line-ofsight (LoS) channel:…”