On the Performance of Rate-Splitting Multiple Access in Coordinated Direct and Relay Transmission

This paper introduces rate splitting multiple access (RSMA) in coordinated direct and relay transmission (CDRT) to improve spectrum efficiency and system performance. In the proposed system, a base station (BS) communicates directly with user equipment 1 (UE1) and through decode and forward (DF) relay with user equipment 2 (UE2). Here, the DF relay works in half-duplex relaying (HDR) mode. A passive intelligent reflecting surface (IRS) is synergistically combined with a DF relay called the hybrid relay network (HRN) to provide beneficial multipath diversity. We hereby derive the analytical expressions of outage probability and ergodic capacity of the HRN system. Asymptotic analysis of outage probability is also done. Through simulation results, the analytical expressions derived are verified.