Outage Performance of NOMA-Based Hybrid Satellite-Terrestrial Relay Networks

In this letter, we investigate the outage probability (OP) of amplify-and-forward hybrid satellite-terrestrial relay networks with a nonorthogonal multiple access (NOMA) scheme. By assuming that a single antenna satellite communicates with multiple multiantenna users simultaneously through the help of a single antenna relay and the NOMA scheme, we first derive the closed-form OP expressions for each NOMA user. Then, asymptotic OP expressions at the high signal-to-noise ratio regime are also obtained to evaluate the achievable diversity order and coding gain. Finally, simulations are provided to the validity of theoretical results, the superiority of introducing the NOMA scheme in satellite-terrestrial relay networks, and the effect of key parameters on the performance of NOMA users.