Adaptive Two-Way Relaying and Outage Analysis

This paper analyzes the outage performance of cooperative protocols for the two-way relaying model in which a half-duplex relay assists in the bi-directional communication of two terminals. We first define the outage events and derive closed form results for the outage probabilities of conventional nonadaptive Amplify-and-Forward (AF) and Decode-and-Forward (DF) two-way relaying protocols. We then consider a simple adaptive protocol in the two-way relaying scenario, which switches between AF and DF depending on the decodability of the two bi-directional data streams at the relay. We also derive the outage probability for this adaptive scheme in closed form expressions, and our results show that it always outperforms the non-adaptive schemes. All the closed form results derived in this paper are applicable to arbitrary channel gains between terminals.