Rate bounds for MIMO relay channels using precoding

Relay channels plays a central role in next-generation multihop wireless systems. This paper considers the MIMO relay channel where multiple antennas are employed by each terminal. New lower bounds on the capacity of a Gaussian MIMO relay channel are derived under the assumption that the transmitter employs either superposition coding or dirty-paper coding. The proposed lower bounds improve on a previously proposed lower bound that arises from a simple transmit strategy.