Outage Performance of Cognitive Relay Networks with Primary User´s ISR Constraint

In the underlay spectrum sharing systems, secondary users (SUs) are allowed to transmit their data in the licensed spectrum band when primary users(PUs) are also transmitting, as long as the transmission of SUs do not interfere PUs´ communications. In cognitive relay networks, the source and relay nodes both need to tune their transmit power to mitigate the interference to PU. In this paper, we investigate the outage performance of cognitive relay networks with PU´s interference to signal ratio (ISR) constraint, where both average and peak ISR constraint are considered. Finally, We derive the exact outage probability in the scenario without cooperation and the upper bound of outage probability in the scenario with cooperation.