Improved Channel Estimation in OFDM Systems with Synchronization Errors and Back-Off

In orthogonal frequency division multiplexing (OFDM) systems, synchronization errors in the receiver cause a linear phase rotation at the output of the discrete Fourier transform (DFT) block. The correlation between the channel coefficients at different subcarriers is weakened due to this phase rotation. As a result, the performance of minimum mean-square error (MMSE) channel estimation degrades significantly. In this paper, we propose two novel algorithms to improve MMSE channel estimation under synchronization errors. Theoretical analysis and simulation results are presented to compare the performance of the proposed algorithms with that of the conventional algorithm.