Power Allocation and RIS Elements Optimisation for Reconfigurable Intelligent Surfaces assisted RSMA

This paper proposes power allocation and the number of reconfigurable intelligent surfaces (RIS) elements optimisation in a RIS-assisted rate splitting multiple access (RSMA) system. The optimised RIS-RSMA (ORIS-RSMA) method determines the optimal number of RIS elements and the power allocation factors for both common and private parts of a message. Additionally, it maximises the sum rate while ensuring that a target common rate is satisfied. The performance of the proposed ORIS-RSMA is compared to that of the conventional RIS-RSMA and RSMA. Simulation results show that ORIS-RSMA achieves a higher sum rate.