Institute of Electrical & Electronic Engineers
Relay selection is an effective way to achieve considerable performance gains in Cognitive Relay Networks (CRN). In practice, the best relay may not always be selected, thus the study of the Nth best relay selection will be very beneficial for CRN design. In this paper, performance analysis for underlay cognitive decode-and-forward relay networks with the Nth best-relay selection scheme is studied over independent and identically distributed (i.i.d.) Rayleigh fading channels. Closed-form expression for the exact outage probability is derived, which can be used to evaluate the impact of the relay selection scheme, the number of relays, the interference power constraint and the transmit power limit on the outage performance.