A feedback-aided rate-split decode-and-forward protocol for static cooperative communications

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 R
2
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.