Channel Estimator with Time Spread Tracking for OFDM systems
An improved channel estimator with time delay tracking measurement for OFDM systems is proposed by exploiting the inherent correlation between the cyclic prefix and port of the received OFDM signal. This scheme make use of real time measured size of inter-symbol interference (ISI) free window to estimate the maximum delay spread of channel, then a transform domain channel estimator is adopted to further reduce the noise variance. Due to the ISI-free window can be estimated before the application of FFT to the received signal, it is a parallel processing, and very suitable for the practical systems. Simulation result demonstrated that the proposed method can track the variation of delay spread of wireless channel, and improve the MSE of channel estimation significantly, thus give at least 1-dB improvement in ITU PA3 channel and 0.5-dB in ITU PB3 channel