Outage Analysis of Cognitive Relay Networks with Interference Constraints in Nakagami-m Channels

This letter evaluates the outage probability of cognitive relay networks based on the underlay approach, while considering the mutual interference between cognitive system and primary system in Nakagami-m fading channels. Closed-form and asymptotic outage expressions are derived. Specifically, we reveal that the diversity is only determined by the fading parameters of the cognitive system. Additionally, the primary network only affects the coding gain of the cognitive system. Finally, it is shown from the simulation results that the derived closed-form expression matches the simulated results perfectly, and the asymptotic analysis keep tight in the high maximum transmit power of cognitive system.