Robust multiuser beamformers in MIMO-OFDM systems

Multiple antennas at the transmitter and the receiver have the potential to either increase the data rate through spatial multiplexing or enhance the quality of transmission through exploitation of diversity. In this paper, we address the problem of multi-user multiplexing using spatial diversity techniques for a MU-MIMO OFDM system so that a basestation could serve multiple users in the same frequency band enabling a substantial saving in bandwidth utilization. Existing techniques require nearly perfect knowledge of the channel state information at the transmitter, which is typicafly not available in practice. In this paper, we design robust transmitter to account for the errors in channel state estimates, which in this case arises due to mean CSI feedback.