On Diversity-Multiplexing Tradeoff in Multiple-Relay Networks

This paper studies the setup of a multiple-relay network in which K half-duplex multiple-antenna relays assist in the transmission between a/several multiple-antenna transmitter(s) and a multiple-antenna receiver. Each two nodes are assumed to be either connected through a quasi-static Rayleigh fading channel, or disconnected. We propose a new scheme, which we call random sequential (RS), based on the amplify-and-forward relaying. We prove that for general multiple-antenna multiple-relay networks, the proposed scheme achieves the maximum diversity gain. Furthermore, we derive diversity-multiplexing tradeoff (DMT) of the proposed RS scheme for general single-antenna multiple-relay networks. Finally, we show that for single-antenna multiple-access multiple-relay (K > 1) networks (without direct link between the transmitter(s) and the receiver), the proposed RS scheme achieves the optimum DMT. However, for the case of multiple access single relay setup, the RS scheme reduces to the naive amplify-and-forward relaying and is not optimum in terms of DMT, while the dynamic decode-and-forward scheme performs optimum for this scenario 1 .