Greedy Successive Relaying for the Multicarrier Diamond Relay Channel

We propose a new decode-and-forward (DF) protocol called Greedy Successive Relaying (GSR) protocol for the M-relay multicarrier diamond relay channel. We consider the diamond channel with half-duplex relays. The GSR protocol uses two states and the relays are partitioned into two sets, A and B. In the first state of the GSR protocol, the relays in A will receive messages from the source while the relays in B will transmit messages to the destination. In the second state, the role of the relays will be reversed i.e. the relays in A will be transmitting to the destination while the relays in B will be receiving from the source. The GSR protocol takes advantage of:(1) successive relaying to overcome the half-duplex limitation, and (2) greedy subcarrier allocation across relays to exploit the available diversity from all the relays. The proposed GSR protocol performs significantly better than the existing protocols. Furthermore, under a Rayleigh fading model, the gap from the cutset bound is also observed to be bounded at high power.