Outage of NOMA-based Hybrid Satellite-Terrestrial Relay Networks with Switch-and-Stay Combining

This paper investigates the outage performance of a novel two-user non-orthogonal multiple access (NOMA)-based hybrid satellite-terrestrial relay network (HSTRN), where one user has direct link to the satellite (termed as direct-link user), while the other user needs to seek the help of the direct-link user or a dedicated relay to acquire its desired signal. An adaptive switch-and-stay combining relaying (ASSCR) scheme is proposed for boosting the system performance without excessive use of relaying resources of the network. Exact and asymptotic expressions of the outage probabilities (OPs) of both users are derived under the fixed-gain (FG) amplify-and-forward (AF) protocol. Finally, numerical results are presented to verify the theoretical analysis, manifest the impacts of key parameters on the system performance, and demonstrate the advantages of our proposed network over other benchmarks.