A fast power allocation algorithm for MIMO relay channels

By assuming full-duplex mode, we consider a MIMO relay channel where the receivers have perfect channel state information (CSI) and the transmitters have partial CSI. Lower bound achieving transmit covariance matrices are derived using an iterative algorithm. Lower bound to the capacity is analyzed for three cases depending on the channel covariance matrix. In the first case, lower bound on the capacity is equal to the capacity of the link from source to relay. In the second case, lower bound on the capacity is equal to the multi access channel capacity from source and relay to the destination. In the last case, lower bound on the capacity depends on both multi access channel and source to relay channel. In that case, under a certain practical channel assumption, we propose a fast power allocation algorithm.