Channel estimation and equalization for OFDM system with fast fading channels

A frequency-domain channel estimation and equalization technique is proposed for OFDM system with fast fading channels in this paper. The proposed method, in addition to the conventional method which averages and updates the estimated propagation characteristics on every channel, detects subchannels that are momentarily distorted by noise and inter-carrier-inference (ICI) over the fast fading frequency-selective channels, or by the sudden intercept owing to the shadowing effects. The information of the detected subchannels is used to decide whether or not insert pilot in the corresponding channel. Then we obtain the MMSE equalizer, and get the optimum solution. Through simulation we optimize the coefficients lambda (comparison threshold), alpha (forgetting factor) and beta (MMSE adjust factor). The simulation results demonstrate that the method is effective for OFDM system with fast fading channels.