A Practical Study of Rate-Splitting Multiple Access: Single vs. Multiple Common Messages

With significant attention from academia and, more recently, from industry, rate-splitting multiple access (RSMA) is emerging as a promising physical-layer multiple access technique for future communication systems. However, the current literature landscape lacks empirical studies on RSMA’s practical feasibility. To address this gap, this paper proposes a novel RSMA prototype and conducts experimental evaluations on the effective usage of common messages. In particular, we employ a practical hybrid RSMA approach, where private messages are transmitted in orthogonal time-slots, while common messages are transmitted non-orthogonally. Experimental validations via software-defined radios (SDRs) confirm the practicality of our RSMA prototype, comparing different access mechanisms and rate-splitting approaches, including single and multiple common message schemes. In terms of bit error rate, rate-splitting outperforms conventional access mechanisms for fixed throughput. However, the selection between single and multiple common messages relies on the specific reliability and throughput configurations.