  As a promising downlink multiple access scheme, Rate-Splitting Multiple
Access (RSMA) has been shown to achieve superior spectral and energy
efficiencies compared with Space-Division Multiple Access (SDMA) and
Non-Orthogonal Multiple Access (NOMA) in downlink single-cell systems. By
relying on linearly precoded rate-splitting at the transmitter and successive
interference cancellation at the receivers, RSMA has the capability of
partially decoding the interference and partially treating the interference as
noise, and therefore copes with a wide range of user deployments and network
loads. In this work, we further study RSMA in downlink Coordinated Multi-Point
(CoMP) Joint Transmission (JT) networks by investigating the optimal beamformer
design to maximize the Weighted Sum-Rate (WSR) of all users subject to
individual Quality of Service (QoS) rate constraints and per base station power
constraints. Numerical results show that, in CoMP JT, RSMA achieves significant
WSR improvement over SDMA and NOMA in a wide range of inter-user and inter-cell
channel strength disparities. Specifically, SDMA (resp. NOMA) is more suited to
deployments with little (resp. large) inter-user channel strength disparity and
large (resp. little) inter-cell channel disparity, while RSMA is suited to any
deployment. We conclude that RSMA provides rate, robustness and QoS
enhancements over SDMA and NOMA in CoMP JT networks.
