Performance Analysis of FAS-Assisted RSMA Communication System

Abstract

Fluid antenna systems (FAS) have recently been recognized as a promising enabler for sixth-generation (6G) wireless communications, owing to their ability to dynamically adapt antenna positions within a confined region. Rate-splitting multiple access (RSMA), on the other hand, allows messages to be divided into common and private parts, which can significantly improve the user experience, especially in scenarios with diverse channel conditions. This advantage is particularly pronounced in FAS, where users can dynamically adjust their antennas for optimal performance. In this paper, we investigate the performance of a FAS-assisted RSMA communication system to utilize their synergistic benefits. We consider a scenario where a fixed base station (BS) transmits information to users equipped with a planar fluid antenna. We begin by deriving the joint cumulative distribution function (CDF) of the effective channel at the user by utilizing copula theory to model the correlation between the channel fading coefficients. To gain more insights, delay outage rate (DOR) is derived. Simulation results demonstrates that the integration of RSMA and FAS leads to improved overall system performance compared to conventional single-input single-output (SISO) RSMA systems. The analytical expressions derived are validated through simulation results. © 2025 IEEE.