Resource Allocation for UAV-Assisted RSMA-CDRT With Integrated Forwarding and Transmission

Abstract

This letter investigates resource allocation for a generalized coordinated direct and relay transmission (CDRT) framework assisted by an amplify-and-forward unmanned aerial vehicle (UAV), where the considered UAV simultaneously forwards the base station’s signals and delivers its own local information, yielding a unified transmission architecture well aligned with practical sensing and control applications. To manage the highly coupled interference topology among direct, forwarded, and relay-originated streams, we adopt the rate-splitting multiple access (RSMA) strategy. We formulate a joint optimization of precoding vectors, the UAV amplification matrix, and rate-splitting parameters to maximize the system sum rate. A penalty-based alternating optimization algorithm that combines semidefinite relaxation and successive convex approximation is customized to tackle the intertwined non-convex fractional terms. Simulation results demonstrate substantial sum-rate gains over the pure-forwarding, NOMA, and SDMA schemes in most considered cases, with the advantage becoming more pronounced under full-load and moderately overloaded conditions.