SINR analysis of cognitive underlay systems with multiple primary transceivers in Nakagami-m fading

In this paper the outage probability of a cognitive decode-and-forward relay network operating over Nakagami-m fading channels is evaluated. Based on the underlay approach, secondary transmissions are allowed only in cases where interference constraints on the primary destination receivers are satisfied. Additionally, by taking into consideration the interfering effects coming from the multiple primary transmitters, the signal-to-interference-plus-noise-ratio statistic of the secondary nodes is investigated. The derived results include exact expressions as well as approximated ones for high values of the maximum allowed transmitted power at the cognitive network and/or the interference limited case. We present numerical performance evaluation results for various channel conditions and communication scenarios. These results are complemented by equivalent computer simulated ones, which validate the accuracy of the proposed analysis.