Ergodic Capacity and Outage Probability Analysis of RIS-Aided Hybrid Satellite-Terrestrial Networks.

Using satellites to provide services with ubiquitous coverage is considered as an indispensable part of 6G era. Communication between the satellite and terrestrial user may be interrupted due to the presence of obstacles or deep shadowing, which can be improved by deploying reconfigurable intelligent surfaces (RIS). In this paper, we consider a hybrid satellite-terrestrial network (HSTN) consisting of one satellite, one terrestrial user, and a RIS which is employed to improve the reliability of wireless transmissions between the satellite and the terrestrial user. Performance analysis of the RIS-aided HSTN is carried out by deriving the upper bound of ergodic capacity and approximation of outage probability, respectively. Numerical results show that increasing the number of reflecting elements significantly improves both the ergodic capacity and outage performance of the system. Moreover, improved channel conditions between the satellite and the terrestrial user also contribute to the capacity and reliability of the system.