Achievable Diversity-Multiplexing-Delay Tradeoff for ARQ Cooperative Broadcast Channels

Cooperative broadcast aims to deliver common messages to all receiver nodes in the wireless network by utilizing cooperation between them. This can have many important applications like broadcasting control messages and cellular phone-based teleconference/game among a group of people. In this paper, we will investigate the cooperative broadcast from the diversity-multiplexing-delay (D-M-D) tradeoff point of view, which has become a popular tool in analyzing multiple-input multiple-output (MIMO) and cooperative protocols. The major contribution is that we derive the optimal D-M-D tradeoff curves for arbitrary number of receive nodes and arbitrary maximum number of automatic retransmission request (ARQ) rounds. Interestingly, it is shown that the achievable diversity gain is always restricted by two special situations. Moreover, we have also compared our results with the previous results on the achievable diversity-multiplexing (D-M) tradeoff of cooperative broadcast channels where no delay is taken into consideration.