Cross Entropy Algorithm for Joint Precoding and Transmit Antenna Selection in Multiuser MIMO Systems with Limited Feedback

This paper considers the joint precoding and transmit antenna selection to reduce the hardware cost such as the radio-frequency (RF) chains associated with antennas in the downlink of multi-user multi-input multi-output (MU-MIMO) systems with limited feedback. The joint precoding and transmit antenna selection algorithm requires an exhaustive search (ES) of all possible combinations and permutations to find the optimum solution at transmitter, thus resulting in extremely high computational complexity. In order to reduce the computational load while still maximizing channel capacity, the cross entropy (CE) method is addressed to determine sub-optimum solution. Compared with the conventional genetic algorithm (GA) and random search method, simulation results show that the CE method provides not only a better performance but also a lower computational complexity.