Efficient Ordering Calculation Method Using Frequency Correlation for MU-MIMO-OFDM THP

This paper proposes an efficient ordering calculation method employing frequency correlation in multiuser multiple-input multiple-output orthogonal frequency division multiplexing (MU-MIMO-OFDM) Tomlinson Harashima Precoding (THP). Although the ordering process is effective to improve the transmission performance of THP, it requires a large amount of computational effort due to sub-carrier-based operation. To cope with this problem, the proposed method thins out the sub-carriers conducting the ordering process based on the frequency correlation. The basic idea behind this proposal is that the ordering results are considered to be the same among the neighboring sub-carriers in a relatively small delay spread. Moreover, the frequency correlation is derived from a delay profile which can be determined by multiple transmit antennas. The effectiveness of the proposed method is demonstrated in terms of calculation cost and the bit error rate (BER) by comparing with the traditional MU-MIMO-OFDM THP without thinning.