Characterization of outage performance for cognitive relay networks with mixed fading

We consider a dual-hop underlay cognitive radio network with a single transceiver pair, which utilizes an amplify-and-forward relay to establish end-to-end communication. The secondary nodes, i.e., the transmitter and the relay, obey transmit power constraints, which are imposed within the underlay paradigm, to guarantee that the instantaneous peak interference at the primary receiver will not exceed a certain threshold. Each of the secondary communication links contains a line-of-sight component whereas the external links, to the primary receiver, are subject to Rayleigh fading. For this system model, we analyze the outage probability, investigate asymptotic cases and outline some interesting variations of the proposed setup. Finally, we demonstrate the accuracy of the obtained mathematical expressions via numerical simulations, which corroborate our theoretical findings.