Energy Minimization for Low-Latency Downlink Rate Splitting Multiple Access

This paper investigates the energy minimization problem in a dual-user downlink system with strict delay constraints. To satisfy these delay constraints and balance the trade-off between block length and reliability, we use a normal approximation formula with finite blocklength code (FBC) capacity instead of the traditional Shannon formula. We consider a transmission scheme based on rate splitting multiple access (RSMA). The results show that although the objective function is not convex and does not have a closed-form expression, the RSMA problem can still be approximated to an equivalent convex function to obtain suboptimal solutions. Simulation results demonstrate that the RSMA scheme achieves significant energy savings compared to simpler non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) schemes.