A novel channel estimation and tracking method for wireless OFDM systems based on pilots and Kalman filtering

In this paper, a new on-line channel estimation and tracking method for wireless OFDM systems based on comb-type pilots is developed. Long training sequences are used to estimate the channel response in frequency domain, and a scalar Kalman filtering scheme is designed to refine the channel estimation. To track the channel variations during a long burst packet, estimated pilots via a vector Kalman filtering are used to linearly interpolate and modify the estimated channel response. Both channel AWGN and state variable noise variance are adaptively estimated. Furthermore, to overcome the phase changes across the symbols owing to frequency offset estimation error, pilot based phase compensation scheme is incorporated. The complete algorithm can be processed in real time with much better performance than training sequence based or pilots based channel estimation methods. Simulation results based on 802.11a wireless LAN standard are presented.