Rate-Splitting-Aided Multi-User Cooperation for Next-Generation Vehicular Clusters

The surge in traffic has amplified the need for greater reliability and higher throughput in vehicle-to-vehicle (V2V) communications. While network-coded cooperation (NCC) offers a promising solution, its reliance on overheard signals and susceptibility to network coding noise raise concerns about the quality-of-service (QoS) being provided. To address this, we propose a rate-splitting aided multi-user cooperation (RSMUC) framework, which employs rate-splitting multiple access (RSMA) as a relaying scheme and enhances the QoS by removing the dependency on overheard signals while leveraging the inherent benefits of RSMA. The outage probability analysis of the system is performed, where joint cumulative distribution functions (CDFs) are essential for accurately characterizing the outage performance of both common and private streams. To model the interdependence between these streams, we develop a copula-based framework. The results show close alignment between the simulated results and the derived analytical equations. Comparative evaluations against benchmark schemes, like NCC variants and non-orthogonal multiple access (NOMA) based cooperative systems (NCS), show that RSMUC significantly outperforms existing approaches across various performance metrics like outage probability and throughput. The contribution of RSMA was further verified through comparisons of throughput and packet delivery/drop (%) rates, providing key insights that are crucial in setting vehicular cluster sizes. These findings underscore the potential of RSMUC to enhance reliability and deliver improved QoS in next-generation V2V networks.