Performance of Cooperative Underlay CR-NOMA Networks over Nakagami-m Channels

Non-orthogonal multiple access (NOMA) has been recently regarded as one of the potential multiple access candidates for coming fifth generation (5G) communication networks. In this paper, a two-hop decode-and-forward (DF) cooperative underlay cognitive radio NOMA (CR-NOMA) network over independent but necessarily identical distributed Nakagami-m fading channels is considered.We derive the accurate closed-form analytical expressions for the outage probability of two secondary NOMA user terminals' messages. The derived expressions are supported by the provided Monte Carlo simulations which also validate the accuracy of our analysis.