Transmitter precoding for ICI reduction in OFDM systems

A non-linear Tomlinson-Harashima (TH) pre-coder is proposed for ICI reduction in OFDM. We show the ICI coefficient matrix is approximately unitary and use this property for the precoder design. Our proposed precoder significantly reduces the bit error rate (BER) degradation due to frequency offset. With this proposed design, only partial channel state information (CSI), not including the knowledge of the frequency offset, is needed at the transmitter. Furthermore, the effect of channel mismatch on the precoder scheme is analyzed and demonstrated by simulation results.