Rate-Splitting Multiple Access for Coordinated Multi-Point Joint Transmission

TL;DR

This paper demonstrates that Rate-Splitting Multiple Access (RSMA) significantly outperforms traditional multiple access schemes like SDMA and NOMA in Coordinated Multi-Point (CoMP) joint transmission networks, offering better spectral efficiency and robustness.

Contribution

It introduces optimal beamformer design for RSMA in CoMP JT, showing its advantages over SDMA and NOMA across various deployment scenarios.

Findings

RSMA achieves higher weighted sum-rate than SDMA and NOMA.

RSMA is effective across diverse inter-user and inter-cell channel disparities.

RSMA enhances rate, robustness, and QoS in CoMP JT networks.

Abstract

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.