In this paper, we consider a two-way relaying system where two users communicate with each other with the help of multiple relays and in which every node is equipped with a single antenna. We assume that the relay employs the amplify-and-forward protocol and propose the Nth worst relay selection scheme.

We intend to analyze the system performance of our considered system under two different fading models: lognormal shadowing channels and generalized-K fading channels. More specifically, the outage probability and bit-error-rate expressions of the proposed scheme are derived. Finally, numerical results are provided to verify and illustrate our mathematical analysis.