On optimum MIMO with antenna selection

Wireless communication systems with transmit and receive antenna arrays are studied when antenna selection is used. A case with very limited feedback of information from the receiver to the transmitter is considered, where the only information fed back is the selected subset of transmit antennas to be employed. It is shown that the optimum signaling, for the largest ergodic capacity of a single isolated link with given interference and antenna selection, is generally different from that which is optimum without antenna selection for some range of signal-to-noise ratios (SNRs). In cases with interference, the improvement obtained from using the true optimum signaling approach tends to increase for this range of SNRs. Further, the optimum approach for cases without antenna selection tends to be optimum in fewer cases as interference power is increased.