Rate Splitting and Beamforming Design for RIS-Assisted RSMA-Enhanced ISAC Networks

This letter investigates the design of a communication-centric rate-splitting multiple access (RSMA)-integrated sensing and communication (ISAC) system assisted by reconfigurable intelligent surface (RIS). By jointly optimizing beamforming, rate splitting, and RIS phase shifts, we maximize the sum rate of users while ensuring accurate radar target detection, even amidst multiple interference sources. To tackle the highly non-convex design problem, we capitalize on a block coordinate descent (BCD) framework that facilitates the development of a low-complexity iterative algorithm for achieving an efficient solution. Specifically, our algorithm adopts the weighted minimum mean square error (WMMSE) approach, successive convex approximation (SCA), and the penalty method to handle the challenges in the subproblems. Simulation results unveil that the proposed RSMA-ISAC outperforms traditional space-division multiple access (SDMA)-ISAC frameworks, thereby validating that the integration of RIS enable the performance of RSMA-ISAC to approach that of the communication-only scheme.