RSMA-enhanced ultra-dense network: Joint analysis of coverage and area spectral efficiency

Abstract

In this study, a rate-splitting multiple access (RSMA) approach is proposed to address the challenges in ultra-dense network (UDN) deployments, particularly in optimizing spectrum resource utilization and power allocation. To reflect real-world network deployment scenarios more accurately, a hybrid spatial distribution modeling method based on stochastic geometry is adopted. The locations of small base stations (SBSs) are modeled using a Poisson cluster process (PCP), while the locations of macro base stations (MBSs) are modeled using a Poisson point process (PPP). For the channel model, the Nakagami-m fading model is employed to characterize multipath propagation under both line-of-sight (LOS) and non-line-of-sight (NLOS) conditions. Under this framework, closed-form expressions for the coverage probability and area spectral efficiency (ASE) of the RSMA system are derived. Results show that although the coverage performance of RSMA is degraded compared to traditional schemes in certain scenarios, its coverage probability can be effectively improved by adjusting the channel fading parameters. In high-density SBS deployment environments, the trade-off between the coverage probability and ASE of RSMA system can obtain better benefits on the overall transmission performance.