Abstract—We investigate nonlinear pre-equalization techniques for the downlink of multi-user systems from a transmitter equipped with multiple antennas to non-cooperative single antenna mobile receivers. The contribution of this paper is the derivation of minimum mean square error (MMSE) preequalization for imperfect transceiver calibration at the base station and the resulting nonreciprocal channels. The performance of the proposed schemes is investigated numerically in both, uncoded and coded transmission.