Energy Efficiency of Rate-Splitting Multiple Access, and Performance Benefits over SDMA and NOMA

TL;DR

This paper demonstrates that Rate-Splitting Multiple Access (RSMA) offers superior energy and spectral efficiency compared to SDMA and NOMA in multi-antenna downlink systems, across diverse user scenarios.

Contribution

The study extends previous work by quantitatively analyzing the energy efficiency of RSMA, establishing its advantages over SDMA and NOMA in various deployment conditions.

Findings

RSMA outperforms SDMA and NOMA in energy efficiency across diverse user deployments.

RSMA provides spectral and energy efficiency improvements with lower complexity.

RSMA is more effective in both underloaded and overloaded network regimes.

Abstract

Rate-Splitting Multiple Access (RSMA) is a general and powerful multiple access framework for downlink multi-antenna systems, and contains Space-Division Multiple Access (SDMA) and Non-Orthogonal Multiple Access (NOMA) as special cases. RSMA relies on linearly precoded rate-splitting with Successive Interference Cancellation (SIC) to decode part of the interference and treat the remaining part of the interference as noise. Recently, RSMA has been shown to outperform both SDMA and NOMA rate-wise in a wide range of network loads (underloaded and overloaded regimes) and user deployments (with a diversity of channel directions, channel strengths and qualities of Channel State Information at the Transmitter). Moreover, RSMA was shown to provide spectral efficiency and QoS enhancements over NOMA at a lower computational complexity for the transmit scheduler and the receivers. In this paper, we build upon those results and investigate the energy efficiency of RSMA compared to SDMA and NOMA. Considering a multiple-input single-output broadcast channel, we show that RSMA is more energy-efficient than SDMA and NOMA in a wide range of user deployments (with a diversity of channel directions and channel strengths). We conclude that RSMA is more spectrally and energy-efficient than SDMA and NOMA.