Capacity of multi-antenna systems with adaptive transmission techniques

The capacity of multiple antenna systems in the presence of Rayleigh flat fading is considered under the assumption that channel state information (CSI) is available at both transmitter and receiver. The capacity expression for a general dual antenna array system of multiple transmitter and receiver antennas is derived together with an equation that determines the cut-off value for such a system. It is shown that, compared to the case in which there is only receiver CSI, large capacity gains are available with an optimal power and rate adaptation scheme.