Performance Study of a UCRN Over Nakagami- ${m}$ Fading Channels in the Presence of CCI

In this paper, the impact of co-channel interference (CCI) on the performance of an underlay cognitive radio network over Nakagami-m fading channels is thoroughly presented and analysed. More precisely, a decode-and-forward relay protocol for a cognitive cooperative network is considered. In this study, the impact of both the primary transmitter interference and CCI on the secondary system performance are considered. First, an exact expression for the equivalent signal-to-interference-plus-noise ratio of the secondary system is obtained. Then, the corresponding exact and asymptotic cumulative distribution functions are derived. From this, the exact outage performance for the secondary network is investigated. Furthermore, the equivalent probability density function is obtained and discussed. In addition, approximate expressions for the average error probability and the system ergodic capacity performances are derived. From the results, it can be inferred that the presence of the CCI and primary network interference severely degrades the system performance. Moreover, a higher value of the shape parameter of the desired fading channel gives better performance and diversity gain. In addition, despite the impact of interferences, the secondary network performance gives better results in comparison to the Rayleigh fading channels scenario.