Cognitive Cooperative Networks in Dual-Hop Relaying Asymmetric Fading Channels

In cognitive relay networks (CRNs), all of previous works have considered symmetric fading channels. However, in practical wireless propagation scenarios, it is likely that the different channels associated with secondary user (SU) and primary user (PU) may undergo different fading characteristics. Therefore, in this paper, we assume that the channels of the secondary network (SU-source→SU-relay→SU-destination) are subject to Rician fading whereas the channels of the link from SU to PU experience Rayleigh fading. Based on this framework, the end-to-end outage probability (OP) of CRNs is investigated for two different relaying schemes: i) in the absence of the direct link with decode-and-forward (DF) relay and ii) in the presence of the direct link with the incremental DF relay. In particular, we derive both exact and asymptotic OP for the considered CRNs under asymmetric fading phenomena. Our analysis reveals important insights into the impact of fading parameters on the CRN performance under distinct fading distributions.