New OFDM Channel Estimation Method by Adding a Virtual Channel Frequency Response

A discrete Fourier transform (DFT)-based channel estimation method which exploits outside of the active frequency band is proposed for orthogonal frequency division multiplexing (OFDM) systems. Usually the DFT-based channel estimation method is degraded due to leakage from non-sample locations of the multi-path timing. In the proposed method, an additional virtual channel frequency response is added outside of the active frequency band so that the total channel frequency response is smooth and periodically continuous in the DFT size. This method decreases the leakage effect in the time domain, and therefore has better performance than conventional time domain methods. Simulation results show that the mean square error and block error rate performance of the proposed method is greatly improved, especially in high signal-to-noise ratio regions, for example, MIMO 4times4,16QAM, R=8/9.