Outage Performance of Hybrid Decode-Amplify-Forward Protocol with the nth Best Relay Selection

In this paper, we consider the Hybrid Decode-Amplify-Forward protocol with the th best-relay selection scheme. In the best-relay selection scheme, the best relay only forwards the source signal to the destination, regardless of working in the Amplify-and-Forward mode or the Decode-and-Forward mode. However, the best relay might be unavailable due to some reasons; hence we might bring into play the second, third or generally the th best relay. We derive closed-form expression for the outage probability using the probability density function and moment generating function of the signal-to-noise ratio of the relayed signal at the destination node. Results show that with the th best relay the diversity order is equal to where is the number of relays. Simulation results are also given to verify the analytical results.