STAR-IRS Assisted Rate Splitting Multiple Access with Perfect and Imperfect CSI for 6G Communication

Incorporating cutting-edge technology like rate splitting multiple access (RSMA) and intelligent reflecting surface (IRS) are essential in 6G communications to satisfy the constantly growing needs for more connection, better reliability, and faster data rates. This paper explores the concept of simultaneously transmitting and reflecting IRS (STAR-IRS) assisted RSMA in the presence of both perfect and imperfect channel state information (CSI). STAR-IRS leverages its dual capability to transmit and reflect signals simultaneously, enhancing spectral efficiency and expanding coverage. So far, in literature, STAR-IRS assisted RSMA system is analyzed in terms of outage probability with perfect CSI scenario. So, in this work, we carry out the performance analysis of STAR-IRS in terms of outage probability and sum rate. Firstly, we derive the analytical expression of the outage probability and sum rate. Secondly, we propose a automatic optimization (AO) algorithm for weighted sum rate (WSR) maximization. The performance analysis is carried out by varying power allocation factor to find its optimality. The derived outage probability and sum rate expressions are validated with Monte Carlo simulations. Also, it is found that on using WSR maximization, the sum rate is enhanced for STAR-IRS based RSMA system when compared with the conventional sum rate maximization.