Internet of Vehicles via Rate-Splitting Multiple Access With Antenna and RIS Partitioning

Integrating rate-splitting multiple access (RSMA) and reconfigurable intelligent surface (RIS) into vehicular communication systems for the Internet of vehicles (IoV) offers significant potential for enhancing quality of service, but also introduces challenges in radio resource allocation due to increased system complexity and the heterogeneous movement patterns of vehicles. In this paper, we propose an IoV communication system that leverages partitioned antenna arrays, RIS elements, and subarray-subsurface-vehicle mapping to reduce computational complexity, with RSMA serving multiple vehicles and users therein. This partitioning and mapping approach, combined with a zero-forcing technique that decouples precoding at the base station (BS) and decoding at the user equipment (UE) into a zero-forcing factor and a precoding/decoding factor, effectively mitigates inter-vehicular interference. For sum-rate maximization, we develop an alternating optimization algorithm that incorporates a dynamic partitioning scheme, which divides the BS antennas and RIS elements into subsets and maps them to individual vehicles for transmitting common and private streams to UEs therein. The passive beamforming for each RIS subsurface is optimized using the Riemannian conjugate gradient (RCG) method, while precoding at the BS subarrays and decoding at the UEs are optimized using a weighted minimum mean square error (WMMSE) approach. Simulation results and comparisons with benchmarks demonstrate that the proposed solution achieves robust system sum rate while significantly reducing computational complexity.