Abstract
In this paper, a dual-hop decode-and-forward non-orthogonal multiple access (NOMA) relaying network with relay-assisted diversity is studied. Exact analytical expressions for the outage probability of K NOMA destination users are derived in closed form and validated by Monte Carlo simulations. We then find optimal power allocation coefficients at the source and relaying nodes to minimize the overall outage probability for all NOMA users. Furthermore, we evaluate the impact of imperfect channel state information on the outage probability. Finally, unlike traditional single-relay NOMA networks, despite the increased interference level, the proposed network is able to significantly improve the outage performance of the system.