  In a multi-input multi-output (MIMO) setup, where one side of the link
comprises a linear antenna array, data can be transmitted over the direction of
incident rays. Channel capacity for this setup is studied in this paper. We
define two different setups; one when the energy is constant and equal over all
rays, and one when available energy is evenly distributed over rays. For the
latter, we show that there is an upper bound for channel capacity, regardless
of the number of rays and antennas. Also, we have compared this setup with the
legacy single-input single-output (SISO) AWGN channel.
