Joint Resource Allocation and Beamforming Design in Multi-Cell Multicarrier Uplink RSMA Transmission

This paper studies an elasticity-enhanced uplink architecture that synergistically integrates the coordinated full-spectrum reuse in multi-cell cellular networks with multicarrier rate-splitting multiple access (RSMA). The uplink multi-layer RSMA granularly partitions each user’s data stream by strategically distributing splitted submessages across subcarriers and employing an elaborate decoding order, thereby fully exploiting the available spatial-spectral degrees of freedom. Particularly, the sum rate maximization for the multi-cell system is formulated through joint optimization of the user association, uplink power allocation, submessage-specific subcarrier assignment, receive beamforming, and decoding order. To tackle the problem’s non-convexity and mitigate the centralized computational burden, a two-stage approach is developed. First, a low-complexity base station (BS) selection method, grounded in matching games, is proposed to partition the user set. Next, a collaborative distributed scheme is proposed to delegate computational process to the corresponding BSs, where each BS independently addresses the remaining local problems using an alternating optimization algorithm. Specifically, the majorization-minimization (MM) and dual decomposition techniques are employed to derive the suboptimal solutions for the power and subcarrier allocation, while the fractional programming and alternating direction method of multipliers (ADMM) are utilized to achieve closed-form updating of the receive beamforming. Moreover, a dynamically optimized decoding order strategy is analytically derived. Simulation results validate the efficacy of the proposed algorithm in sum rate gain and computational complexity, showcasing that the RSMA-aided multi-cell collaborative transmission can attain superior performance than existing schemes.