Rate-Splitting Multiple Access for Multigateway Multibeam Satellite Systems with Feeder Link Interference

TL;DR

This paper introduces a rate-splitting multiple access (RSMA) strategy for multigateway multibeam satellite systems, demonstrating its effectiveness in improving fairness and performance under practical constraints like interference and imperfect channel knowledge.

Contribution

It proposes a novel RSMA-based beamforming scheme for satellite systems, addressing max-min fairness with imperfect CSIT and feeder link interference, and compares it with conventional methods.

Findings

RSMA achieves higher max-min fairness rates than traditional precoding.

Using on-board processing (OBP) enhances the benefits of RSMA.

RSMA is effective under practical satellite system constraints.

Abstract

This paper studies the precoder design problem of achieving max-min fairness (MMF) amongst users in multigateway multibeam satellite communication systems with feeder link interference. We propose a beamforming strategy based on a newly introduced transmission scheme known as rate-splitting multiple access (RSMA). RSMA relies on multi-antenna rate-splitting at the transmitter and successive interference cancellation (SIC) at the receivers, such that the intended message for a user is split into a common part and a private part and the interference is partially decoded and partially treated as noise. In this paper, we formulate the MMF problem subject to per-antenna power constraints at the satellite for the system with imperfect channel state information at the transmitter (CSIT). We also consider the case of two-stage precoding which is assisted by on-board processing (OBP) at the satellite. Numerical results obtained through simulations for RSMA and the conventional linear precoding method are compared. When RSMA is used, MMF rate gain is promised and this gain increases when OBP is used. RSMA is proven to be promising for multigateway multibeam satellite systems whereby there are various practical challenges such as feeder link interference, CSIT uncertainty, per-antenna power constraints, uneven user distribution per beam and frame-based processing.