Cooperative diversity in space-time coded wireless networks

The use of spatial diversity methods is an effective way to counter the adverse effects of fading in wireless channels. Cooperative networks aim to utilize the available terminals as a collection of distributed antennas for the transmission of signals from one end of the network to the other. This technique is especially effective in providing spatial diversity when having more than one antenna in the transmitter and/or receiver is not practical or cost-effective. Even with multiple antennas available, cooperation amongst terminals could provide additional spatial diversity. In this paper, we investigate a cooperative strategy, in which the transmitter uses a block space-time code. Here, one or more terminals can be designated as partner stations which either re-transmit their received signal after simple amplification or after appropriate processing. We obtain analytical expressions for the error rate performance of the systems considered. Analytical and simulation results show that the added spatial diversity achieved improves the error rate performance of the system quite remarkably.