This paper presents a pilot-symbol-aided channel estimator for orthogonal frequency division multiplex (OFDM) wireless communication systems. The proposed scheme is highly robust to time variation of wireless channels. In addition, it is equivalent to the conventional two-dimensional (2-D) minimum mean-square error (MMSE) channel estimator but with much reduced computational complexity. The reduction in complexity is achieved by employing the two-dimensional (2-D) inverse fast Fourier transform (IFFT), 2-D FFT and a 2-D weighting function instead of a 2-D filter. The weighting function is derived based on the mean-squared error (MSE) criterion. For cases where channel statistics are not available, we propose a robust estimator based on a simple 2-D windowing function. Furthermore, we propose an enhanced channel estimator that can further improve the performance of the robust estimator. Simulation results demonstrate that the proposed robust and enhanced estimators are highly effective for realistic situations without the need for channel statistics.
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