Fluid Antenna-Aided Rate-Splitting Multiple Access

TL;DR

This paper investigates a novel combination of fluid antenna systems with rate-splitting multiple access, demonstrating significant performance improvements over traditional schemes through analytical and numerical analysis.

Contribution

It introduces a new FAS-aided RSMA framework, deriving the channel distribution and outage probability, and shows its superiority over TAS and NOMA in downlink transmission.

Findings

FAS combined with RSMA outperforms TAS and NOMA in outage probability.

Analytical expressions for channel gain distribution and outage probability are derived.

Numerical results confirm the practical benefits of FAS in RSMA systems.

Abstract

This letter considers a fluid antenna system (FAS)-aided rate-splitting multiple access (RSMA) approach for downlink transmission. In particular, a base station (BS) equipped with a single traditional antenna system (TAS) uses RSMA signaling to send information to several mobile users (MUs) each equipped with FAS. To understand the achievable performance, we first present the distribution of the equivalent channel gain based on the joint multivariate t-distribution and then derive a compact analytical expression for the outage probability (OP). Moreover, we obtain the asymptotic OP in the high signal-to-noise ratio (SNR) regime. Numerical results show that combining FAS with RSMA significantly outperforms TAS and conventional multiple access schemes, such as non-orthogonal multiple access (NOMA), in terms of OP. The results also indicate that FAS can be the tool that greatly improves the practicality of RSMA.