Space-time processing for cooperative relay networks

Future wireless communication systems have to support high data rates. The capacity of these systems can be increased dramatically by using multiple antennas at the transmitter and the receiver working in a rich scattering environment. However, in a line-of-sight environment, the MIMO channel matrix is rank deficient, and therefore the capacity increase diminishes. Using cooperative amplify and forward relay nodes, it is possible to overcome this problem by increasing the rank of the MIMO channel. A special signaling scheme is necessary to achieve this increase of channel rank. Therefore the use of existing space-time algorithms is not straightforward. We show that a recently proposed class of linear space-time block codes exploits the offered capacity and achieves good performance results. The codes are able to use transmit diversity in combination with spatial multiplexing with reasonable and scalable computational complexity.