Improving the Diversity-Multiplexing Tradeoff With Repetition-Coded Relaying in Wireless Downlink

Repetition-coded relaying using half-duplex relays offers an easy way of achieving cooperative diversity that works well with apparently any source transmission schemes, but at the same time presents a potentially serious problem of inefficient spectrum utilization. Poor Diversity-Multiplexing Tradeoff (DMT) is often reported. This paper investigates efficient ways of using repetition-type decode-and-forward relaying to improve the DMT of users in a wireless downlink. The authors deliberately align the relaying operation of one user with the source transmission for another user and show that the arisen inter-user and inter-relay interference could be efficiently managed without the need of transmit-side channel state information thanks to the downlink network topology and simple user scheduling.