A Technique for Multiuser and Intercarrier Interference Reduction in Multiple-Antenna Multiuser OFDM Downlink

The authors propose a two-stage precoder/equalizer to suppress InterCarrier Interference (ICI) and MultiUser Interference (MUI) in downlink multiuser OFDM with multiple transmit antennas. The first stage, non-linear Tomlinson-Harashima Precoding (THP) at the Base Station (BS) transmitter, mitigates the effect of the spatial inter-stream interference caused by transmission from multiple transmit antennas to decentralized users. In the second stage, each user's receiver employs low-complexity iterative linear Minimum Mean-Square Error (MMSE) equalization to suppress the ICI due to frequency offset.