Adaptation of decode-forward two-way relaying to fading links: A rate and power analysis

In this paper, we analyze a full-duplex composite decode-and-forward scheme for the two-way relay channel in a Rayleigh fading environment. Designed from a link-state perspective, this scheme combines both block Markov and independent coding, and yields relay power savings in some link-state regimes. For a given distance configuration of nodes, we analytically determine the probability of each link-state regime in Rayleigh fading, which always spans the relay power saving regimes. As such, relay power savings are realizable for almost any distance configuration. Further, we evaluate the throughput when only long-term channel state information (CSI) is available instead of perfect CSI, which still shows substantial gain over not using the relay. Numerical results illustrate significant relay power savings for most distance configurations and highlight an inherent tradeoff between achievable rate and power savings at the relay.