Bidirectional decision feedback equalization for mobile MIMO-OFDM systems

Orthogonal frequency division multiplexing (OFDM) combined with multiple transmitter and receiver antennas (MIMO) is a promising technique for high-speed wireless transmissions. However, severe intercarrier interference (ICI) coming from high mobility of user equipment corrupts the orthogonality of the OFDM and pulls down the system performance. From the analysis of the ICI channel matrix, it is revealed that the interference can be effectively bounded in finite double-side subcarriers centering the desired subcarrier. In this paper, we propose bi-directional decision feedback equalizer (BD-DFE) to tackle ICI problem for the mobile MIMO-OFDM system. The equalizer consists of two-part equalizers. The upper part uses DFE to output tentative decisions. The lower part employs BD-DFE aiming to cancel both pre- and post-cursor ICI to give a finial symbol estimates. In so doing, double-sided ICI can be removed more completely. Simulation results show that our proposed receiver for the mobile OFDM system provides good tradeoffs between receiver performance and computational load.