Outage and Capacity Analysis of HRIS-Aided RSMA Systems

Rate-splitting multiple access (RSMA) has emerged as a promising non-orthogonal transmission scheme with efficient interference management. On the other hand, a hybrid active-passive reconfigurable intelligent surface (HRIS) can enhance wireless channels by simultaneously reflecting and amplifying incident signals. In this paper, we explore the synergistic advantages of integrating these technologies within an HRIS-assisted RSMA system. We derive highly accurate expressions for the system's outage probability and ergodic capacity under Nakagami-$m$ fading channels and successive interference cancellation errors, leveraging the moment-matching technique. Furthermore, we present the asymptotic expressions for the outage probability and ergodic capacity to unveil important insights into the diversity order and coding gains of the system. Finally, we provide extensive numerical results to validate the analytical findings.