Phase Shift Design for RIS-Assisted Satellite-Aerial-Terrestrial Integrated Network

The reconfigurable intelligent surface (RIS) has been studied for integration into satellite-aerial-terrestrial integrated networks to boost the received signal power without the additional power consumption by coordinating the passive reflecting elements' phase shift at the RIS. However, the RIS may cause inter-satellite interference to terrestrial users due to the reflection of multiple satellites' transmissions. Therefore, this article proposes the optimal reflection, i.e., passive beamforming, of the RIS to maximize the terrestrial user's received signal-to-interference-plus-noise ratio when the interfering satellite exists. The numerical analysis and simulation results demonstrate the effectiveness and feasibility of the RIS against the interfering satellite, the optimality of the proposed reflection vector, and the superiority of the phase search algorithms in the practical discrete phase shift model.