Outage Performance of RIS-Aided NOMA ISAC Network for LEO Satellite System

This paper investigates outage probability in a reconfigurable intelligent surface (RIS)-aided non-orthogonal multiple access (NOMA)-integrated sensing and communication (ISAC) system within satellite communications. We model satellite channels exploiting a shadowed-rician distribution and terrestrial channels with a nakagami distribution. Closed-form exact outage probabilities for both perfect and imperfect successive interference cancellations (SIC) are derived and validated through Monte Carlo simulations. Additionally, an asymptotic outage expression and the corresponding diversity gain are derived, illustrating the influence of system parameters on the outage probability decay rate. Through extensive simulations, we demonstrate that RIS can greatly enhance outage performance, despite the impacts of imperfections in channel state information (CSI) and SIC. We further examine outage performance under both heavy and moderate shadowing conditions. Furthermore, we provide a beam pattern for the detection of aerial targets from LEO satellites.