On a model and capacity of MIMO channels

A model of a MIMO fading channel is considered which does not assume that the discrete-time axis is divided into long intervals with a constant channel. It assumes only that there are $\ell$ possible states (or subchannels) of the channels, and at each moment both the transmitter and receiver know the channel state. The average input power in the subchannels can be different and not equal to the average input power over the full time axis. We obtain a lower bound for the capacity of the considered vector channel. Also, we consider a vector channel with one transmitting and two or more receiving antennas. We obtain optimum distributions of the average power over the subchannels and lower bounds for the channel capacity.