Investigating the effects of primary users within cognitive relay networks with Rayleigh fading

This paper investigates the effects of a primary user (PU) within a cognitive amplify-and-forward (AF) network using general selection combining (SC) techniques whilst under the influence of non-identical Rayleigh fading channels. The net- work´s operation will be determined mathematically by deriving a closed-form expression for the network outage probability (OP) from expressions for the probability density functions, cumulative distribution functions of the end-to-end signal to interference noise ratios (SINR) for the channel links. Also, asymptotic calculation is used to define the upper bound of the power transmit constraint for optimal performance within an underlay spectrum. The effects of a moving primary user are also investigated by using MATLAB simulations. The results will be displayed graphically and denote the primary user in three unique places based on an (x, y) co-ordinate system.