Cooperative transmission in wireless networks with delay constraints

By using distributed antennas, the cooperative transmission strategy provides powerful benefits of multiantenna systems without the need for physical arrays. In this paper, network nodes are fed by bursty data sources and the delay constraints of data services are considered. The time-varying fading channel is modelled as a Markov process to characterize the channel correlation. Utilizing an orthogonal space-time coding scheme, we propose a cooperative scheduling protocol for buffer management and packet transmission. Two scenarios are discussed where either no channel state information (CSI) or quantized CSI is available at the transmitters. The optimal protocol minimizes the average transmit power while guaranteeing the delay requirements. The contribution of this work is to examine the impacts of the temporal variation of fading channels and the delay sensitivity of data sessions on the performance of the cooperative protocols. Results show that the benefits provided by cooperative protocols diminish with strict delay constraints or with fast-varying channels.