Performance Analysis of RIS-Assisted Fluid Antenna Systems Over Rician Fading

Abstract

This paper presents performance analysis of reconfigurable intelligent surface (RIS)-assisted fluid antenna systems (FAS) over Rician fading channels, capturing realistic line-of-sight conditions between the base station (BS), RIS, and user. The system comprises of a BS transmitting via a RIS to a user equipped with a spatially correlated FAS, where the optimal port is selected for reception in the absence of a direct link. Closed-form approximations of the equivalent channel gain distribution are derived using the central limit theorem and Laguerre series expansion, incorporating the Rician fading model. Based on these approximations, analytical expressions for outage probability (OP) and delay outage rate (DOR) are obtained and benchmarked against Rayleigh fading scenarios. The impact of key system parameters on OP and DOR is extensively analyzed, and the theoretical results are validated via Monte Carlo simulations. © 2012 IEEE.