Improved DFT-Based Channel Estimation for OFDM Systems with Null Subcarriers

We propose two new techniques to mitigate the "edge effect" of the traditional Discrete Fourier Transform (DFT)based channel estimator for OFDM systems with Null subcarriers. Both techniques try to reduce the "edge effect" by generating virtual pilots (VP) in the receiver to fill the missing pilots in the Null spectrum. In the first technique, VPs are generated such that the channel frequency response (CFR) has "continuous" transition between the active and Null spectrums. The second technique is a simplified alternative of the first technique with much lower complexity at very little performance loss. Computer simulations conducted in static frequency selective channels shows that both proposed new techniques outperform previously proposed DFT-based channel estimators in terms of bit error rate (BER) and channel estimation mean square error (MSE).