Performance analysis of DF-relayed cognitive underlay networks over EGK fading channels

In this paper, we analyse the performance of a dual hop cognitive radio underlay network employing a decode and forward relay. The fading channels have been modeled using extended generalized-K fading statistics. The interference temperature is taken as a constraint so that the transmit power of the secondary source and the relay do not exceed this value. This limits the transmit powers of the secondary network to ensure no interference with the primary communication which is imperative in cognitive underlay systems. First the signal to noise ratio at the relay and the destination of the system under consideration are analyzed and then the respective cumulative distribution function and probability density function are evaluated. This is followed by the derivation of statistical expression for end-to-end signal to noise ratio of the relay network, it's cumulative distribution function and probability density function. These expressions are further utilized to derive the analytical expressions for the outage probability and the ergodic capacity of the underlay dual-hop cognitive relay network. Our results demonstrate the dependence of the performance of the system on various parameters under the constraints of transmit power and interference temperature already defined. The mathematical analysis is followed by various numerical examples to illustrate how the various parameters of the system affect it's performance.