Outage probability analysis of a diamond relay network with opportunistic spectrum access

In this paper, we investigate the outage probability of a wireless two relay (diamond relay) network which consists of a source, a destination and two network clusters. Each cluster is defined by a number of cognitive nodes (unlicensed) and a primary node (licensed). The cognitive nodes relay the source information by employing opportunistic spectrum access. We consider amplify-and-forward (AF) relaying protocol to evaluate the closed-form expression of outage probability in non-identical independent Rayleigh fading channels. The unavailability of the spectrum causes an increase in the outage probability and a reduction in the achievable diversity. An improvement of the performance can be provided if the neighbouring nodes within a cluster sense the spectrum cooperatively.