A Simplified Decision-Feedback Channel Tracking Scheme for MIMO-OFDM Systems

This paper proposes a simplified decision-feedback channel tracking scheme for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems designed for wireless LANs. In the proposed scheme, the channel matrix for each subcarrier is tentatively estimated from a replica matrix of the transmitted signal. A number of the estimated channel matrices, each determined for a different timing, are combined, and the previously estimated channel matrices are replaced by the latest ones. The packet error rate (PER) performances for the proposed scheme are evaluated by computer simulations. Assuming 5 GHz band operation, the proposed scheme keeps the PER degradation at PER=10^-2 to less than 1 dB when the velocity of transmitter is less than 11.8 km/h. The result represents the proposed channel tracking scheme provides sufficient mobility for wireless LAN systems. We also evaluate the computation complexity of the proposed scheme. The proposed scheme requires less than 1% of the complex multipliers needed by the conventional channel tracking scheme based on Kalman filters.