Performance Evaluation of Outage Probability for Half-Duplex Asymmetric Bi-directional Decode-and-Forward Relaying

This paper addresses the problem of outage evaluation for a decode-and-forward based bi-directional communication network. We consider a three-node scenario, where two end-sources wish to communicate to each other with the help of a relay node, and each terminal has a single antenna and operates in a half-duplex manner. Unlike the existing works, we deal with this problem from the view point that system has asymmetric traffic flows (i.e., asymmetric bi-directional relaying). As a first step, we characterize the achievable rate region for the examined network scenario. Given the obtained achievable rate region, outage probability is defined accordingly. Then, the conventional three-node network is evaluated in terms of outage probability and the corresponding closed-from expressions are developed over Rayleigh fading channels. After that we get insights into the impact of traffic asymmetry on the system outage probability, which manifest that generally the system outage probability is related to the two parallel channels simultaneously, however, the metric can be determined only by the link with greater information rate when the level of traffic asymmetry is above a certain threshold. Finally, simulation experiments are conducted, which verify our proposed studies.