Coordinated Rate-Splitting Multiple Access for Integrated Satellite-Terrestrial Networks with Super-Common Message

TL;DR

This paper proposes a coordinated rate-splitting multiple access framework for integrated satellite-terrestrial networks, optimizing message splitting and power allocation to improve fairness and interference mitigation.

Contribution

It introduces a novel inter- and intra-network rate-splitting scheme with a super-common message, tailored for satellite-terrestrial networks with imperfect channel information.

Findings

Outperforms traditional methods in interference scenarios

Enhances fairness among satellite and terrestrial users

Demonstrates robustness under various propagation conditions

Abstract

Rate-splitting multiple access (RSMA) is an emerging multiple access technique for multi-antenna networks that splits messages into common and private parts for flexible interference mitigation. Motivated by its robustness and scalability, it is promising to employ RSMA in integrated satellite-terrestrial networks (ISTN), where a satellite serves satellite users (SUs) broadly with a multibeam multicast transmission while terrestrial base station (BS) serves cellular users (CUs) with a unicast transmission, operating in the same frequency band. To avoid the data exchange between satellite/cellular networks via backhaul, we assume a coordinated ISTN relying on imperfect channel state information. We put forth a coordinated RSMA framework tailored to the coordinated ISTN by applying inter-network rate-splitting (RS) with a super-common message on top of intra-network RS with common/private messages. With the unified RS design for inter- and intra-networks, we jointly optimize the precoding and power allocation of the private/common/super-common messages to achieve max-min fairness among all SUs and CUs through successive convex approximation. By doing so, the power of the super-common message can be adjusted according to interference levels of the satellite towards CUs, thereby potentially mitigating inter-network interference. Simulation results demonstrate the superiority and robustness of our approach to cope with various interference and propagation conditions.