Outage probability analysis of RIS-assisted RSMA systems over Nakagami-m fading channels

Abstract

In this study, we propose and analyze an RIS-assisted rate-splitting multiple access (RSMA) system. The framework enhances transmission efficiency by simultaneously exploiting both the direct and RIS-reflected links to serve two users. For practical considerations, imperfect successive interference cancellation (SIC) is taken into account. Under the Nakagami-m fading channel model, closed-form expressions for the outage probability (OP) and energy efficiency (EE) are derived and verified through Monte Carlo simulations with a large number of iterations. Furthermore, a comprehensive comparative analysis with a benchmark RIS-assisted non-orthogonal multiple access (NOMA) scheme is conducted. Simulation results show that the proposed system significantly outperforms its NOMA counterpart in terms of OP. The impacts of key system parameters, including the number of RIS reflecting elements, transmit power, carrier frequency, fading severity, and SIC imperfection level, are thoroughly investigated. These findings demonstrate the strong potential of RIS-assisted RSMA as a promising solution to enhance the reliability of future sixth-generation (6G) wireless networks.