Underlay Spectrum Sharing for NOMA Relaying Networks: Outage Analysis

In this paper, we investigate a cognitive non-orthogonal multiple access (NOMA) network scenario by adopting an amplify-and-forward (AF) relaying method. The end-to-end outage probability (OP) for secondary users is studied. Then, we compare the OP for the NOMA and time-division multiple access techniques and demonstrate that the former one outperforms the latter. Moreover, the proposed AF protocol is compared to the detect-and-forward one. Finally, the simulation results validate the derived analytical expressions.