Optimal Resource Allocation Towards Energy Efficiency in RSMA-URLLC IIoT Networks

To meet the stringent requirements of latency, reliability and energy efficiency (EE), we introduce rate splitting multiple access (RSMA) into ultra-reliable and low-latency communication (URLLC) IIoT networks, where RSMA has a good flexibility in interference management. By jointly optimizing beamforming design and common rate allocation, we investigate the worst-case EE maximization problem with imperfect channel state information (CSI). Although the problem is nonconvex, we exploit the monotonicity of the problem to develop an optimal solution, where a monotonic optimization framework based on polyblock outer approximation (PA) and boundary searching is proposed to find the optimal points on the Pareto boundary. Simulation results show the convergence of the proposed optimal algorithm, and RSMA can achieve higher EE than space division multiple access (SDMA) and non-orthogonal multiple access (NOMA) in URLLC IIoT scenarios.