Robust Beamforming for Uplink RSMA in UAV Communication Systems With Jittering

Abstract

This letter investigates a robust beamforming (BF) scheme for a rate-splitting multiple access-enabled unmanned aerial vehicle (UAV) uplink communication system under jittering effects. Considering multiple two-user pairs, we formulate a worst-case achievable sum rate maximization problem by jointly optimizing the transmit power of ground users and the receive BF of UAV. The difficulties of this problem arise from the complex trigonometric form of the angle-of-arrival (AoA) uncertainties caused by UAV jitter. To address these challenges, we first derive an approximation method based on the second-order Taylor series expansion to simplify the AoA uncertainties, and then convert the resulting random quadratic forms into deterministic forms by applying S-Procedure. Based on these, we propose a penalty function-based successive convex approximation algorithm to obtain a suboptimal solution to the original problem. Simulation results demonstrate the robustness and superiority of the proposed robust BF scheme.