Fluid Antennas Empowered RIS-Aided Integrated Sensing and Communication Systems
TL;DR
This paper proposes an FA-empowered integrated sensing and communication (ISAC) system in which a reconfigurable intelligent surface (RIS) is employed to mitigate performance degradation in communication and sensing caused by blockages of line-of-sight links.
Abstract
Fluid antennas (FAs) represent a key enabling technology for the evolution of next-generation wireless networks. In this paper, we propose an FA-empowered integrated sensing and communication (ISAC) system in which a reconfigurable intelligent surface (RIS) is employed to mitigate performance degradation in communication and sensing caused by blockages of line-of-sight links. We consider a joint optimization of transmit beamforming matrices, RIS coefficients, and transmit antenna positions to maximize the sum rate subject to power budget, RIS, and antenna spacing constraints, as well as flexible regions. Due to the non-convexity and complexity of the objective, the alternative algorithm-based framework is used to iteratively solve the original optimization problem, in which the problem is decomposed into several subproblems using the fractional programming algorithm. Specifically, the subproblems regarding precoding, RIS phase shifts, and antenna positions are efficiently solved using semidefinite relaxation, Riemannian steepest-descent, and majorization minimization algorithms, respectively. Simulation results demonstrate the efficiency and superiority of the proposed framework over the conventional RIS-aided fixed-position antenna ISAC system.