Capacity Bounds for Alternating Two-Path Relay Channels

Abstract

We propose a decode-and-forward (DF) strategy for a relay channel with two half-duplex relays that alternately forward their received messages. The proposed strategy is to combine two distinctive schemes which differently treat a codeword that each relay receives from the other relay. One lets each relay consider it as interference, while the other makes each relay decode and forward it to the destination. We show the channel conditions under which each scheme outperforms the other and combining both schemes is better than simply choosing the best of them. Even though we can verify that the proposed DF strategy achieves a cut-set upper bound only in certain cases, we numerically show that the gap between them is relatively small or negligible for most cases.