When RIS Meets GEO Satellite Communications: A New Sustainable Optimization Framework in 6G

TL;DR

This paper introduces a novel optimization framework for RIS-assisted GEO satellite communications in 6G, enhancing spectral efficiency and channel capacity through joint power and phase shift optimization using a Mesh Adaptive Direct Search algorithm.

Contribution

It proposes a new RIS-assisted GEO SatCom system model and an epsilon-optimal algorithm for joint power and phase shift optimization, addressing nonconvex challenges.

Findings

RIS-assisted SatCom improves channel capacity

The proposed algorithm efficiently solves the nonconvex optimization

Simulation confirms enhanced system performance with RIS

Abstract

Reflecting intelligent surfaces (RIS) is a low-cost and energy-efficient solution to achieve high spectral efficiency in sixth-generation (6G) networks. The basic idea of RIS is to smartly reconfigure the signal propagation by using passive reflecting elements. On the other side, the demand of high throughput geostationary (GEO) satellite communications (SatCom) is rapidly growing to deliver broadband services in inaccessible/insufficient covered areas of terrestrial networks. This paper proposes a GEO SatCom network, where a satellite transmits the signal to a ground mobile terminal using multicarrier communications. To enhance the effective gain, the signal delivery from satellite to the ground mobile terminal is also assisted by RIS which smartly shift the phase of the signal towards ground terminal. We consider that RIS is mounted on a high building and equipped with multiple re-configurable passive elements along with smart controller. We jointly optimize the power allocation and phase shift design to maximize the channel capacity of the system. The joint optimization problem is formulated as nonconvex due to coupled variables which is hard to solve through traditional convex optimization methods. Thus, we propose a new $\epsilon-$optimal algorithm which is based on Mesh Adaptive Direct Search to obtain an efficient solution. Simulation results unveil the benefits of RIS-assisted SatCom in terms of system channel capacity.