On the Diversity Gain in Cooperative Relaying Channels with Imperfect CSIT

In this paper, we investigate the impact of imperfect channel state information at the transmitters (CSIT) on the achievable diversity gain in a cooperative relaying channel with multiple destination antennas, where the CSIT comes from channel estimation at the transmitters. Both decode-and-forward (DF) and amplify-and-forward (AF) relaying protocols are considered. We show that transmit power control based on the imperfect CSIT significantly improves the achievable diversity gain. The diversity and multiplexing tradeoff (DMT) as a function of the CSIT quality of the source-relay link, source-destination link and relay-destination link is derived for each of the considered relaying schemes. An upper bound on the DMT of the relaying channel is also provided.