A Feedback-Aided Rate-Split Decode-and-Forward Protocol for Static Cooperative Communications

Abstract

A two-phase, rate-split, static nonorthogonal decode-and-forward protocol for the cooperative relay network consisting of a source, multiple half-duplex relays and a destination, all having single antenna, is proposed in this paper. In the proposed protocol, the desired transmission rate R is split into rates R-1 and R-2; then the source sends rate R-1 during the first phase and rate R2 during the second. Explicit expressions for R-1 and R-2, are also given. It is shown that the proposed protocol achieves the optimal cooperative diversity derived from the information theoretic cut set bound in high SNR regime. Compared to the compress-and-forward protocol, the proposed protocol is much simpler for practical implementation, holds the same for any number of relays and requires only local channel-state-information at each node, except for a small feedback of rate R-1 as well as a selection index of relays.