Outage probability of fixed-gain dual-hop relay selection channels with heterogeneous fading

In this paper, we develop a framework that can be used to analyze the outage probability of a dual-hop fixed-gain amplify-and-forward relay system performing single relay selection. We consider three selection strategies: (1) first-hop selection, whereby the relay is chosen to maximize the signal-to-noise ratio (SNR) at the relay irrespective of the second-hop channels; (2) second-hop selection, in which the relay is chosen such that the second-hop SNR is maximized; and (3) dual-hop selection, where the end-to-end SNR is maximized. The proposed analytical framework is capable of treating systems operating in heterogeneous fading conditions, where all or a subset of the source-relay and relay-destination channels has non-identical distributions or even experience completely different fading processes. We apply the framework to calculate new exact series representations of the outage probability for the three aforementioned cases of relay selection when all channels adhere to the Nakagami-mmodel. Our analysis is corroborated by simulations. Finally, we provide a discussion of how the proposed framework can be applied to analyze other fading configurations using the techniques detailed herein.