Rate-Splitting Downlink Transmission in Cell-Free Networks under Fronthaul Constraints

Future communication networks will support heterogeneous services with increasing number of devices and increasing rate requirements. Therefore, it is necessary to develop network architectures that can flexibly adapt to the constraints and requirements from the environment. In this paper, the synergy between rate splitting multiple access (RSMA) and cell-free network architecture is studied. In contrast to recent work, we apply rate splitting (RS) at the central processing unit (CPU) and optimize the rate allocation at the fronthaul links and the power control at the access points (APs) jointly. The derived achievable rate region expressions are applied to an anecdotal cell-free network with two APs and two users served over a standard wireless interference channel. We show that the proposed adaptive RS scheme outperforms the baseline as well as recent state of the art multiple access schemes.