Efficient OFDM Channel Estimation in Mobile Environments Based on Irregular Sampling

We present a novel pilot-aided channel estimation method for OFDM packet transmissions over time-varying channels. The proposed channel estimator is based on 2-D irregular sampling techniques that allow for flexible training data arrangement. The resulting iterative conjugate gradient algorithm involves block Toeplitz matrices and thus has low computational complexity. We apply our scheme to a WLAN system by jointly exploiting preamble and continual pilot subcarriers (that are present for the purpose of frequency offset tracking) for channel estimation. Simulation results confirm the excellent performance of our method, which is thus an attractive add-on to WLAN and WiMAX receivers in high-mobility scenarios.