Secure Performance of DF Relaying in Cooperative NOMA over Rician Fading Channels

In this paper, a Decode-and-Forward (DF) relaying system for Non Orthogonal Multiple Access (NOMA) networks is considered, where the transmitted information between the relay and NOMA users can be overheard by an eavesdropper. In this context, we study the secrecy performance of the considered scenario under combined path loss and Rician fading. We derive novel expressions of the Secrecy Outage Probability (SOP) and the Strictly Positive Secrecy Capacity (SPSC) metrics. More Specifically, we provide the exact SOP and SPSC expressions of the near user. Unlikely, closed form expressions of the SOP and SPSC metrics for the far user are given in high signal-to-noise ratio (SNR) because of the intractable nature of the exact expressions. On this basis, numerical analysis has been firstly conducted to verify the analytical expressions. Then, the results are provided to assess the secrecy performance of our system under the effects of different network parameters.