Message Priority in Two-Way Decode-Forward Relaying

Abstract

In this paper, we examine message prioritization in terms of both rate and reliability in the two-way relay channel using decode-forward relaying. Each source sends both a low priority message and a high priority message. We design a scheme that routes the high priority messages through the relay and direct link but the low priority message is only decoded by the destination. For fixed message priorities, the rate-optimal power allocation is analytically determined based on the link state. The high priority message is guaranteed to have greater reliability than that of the low priority message. We analytically formulate this outage probability from both the perspective of a single user and that of the overall system, and numerically examine the increased reliability for the high priority message.