Outage Performance for Cognitive Relay Networks with Underlay Spectrum Sharing

The outage performance is investigated for a cognitive relay system with underlay spectrum sharing model. It is shown that the dependence among the received SNRs is introduced due to the interference power constraint. The joint probability of the received SNRs is derived. By considering the dependence for the case of null decoding set, a tight lower bound on the outage probability is obtained. Simulation results are presented to verify the theoretical analyses.