A novel method of Doppler shift estimation for OFDM systems

Doppler shift estimation has been deployed to improve the performance of orthogonal frequency division multiplexing (OFDM) systems. A novel method of Doppler shift estimation for OFDM systems in time varying and frequency selective fading channels has been proposed and investigated. The proposed method is a frequency domain scheme that utilizes pilot subcarriers, which are adopted in most practical OFDM systems. An equation consisting of the Doppler shift has been derived from the ratio of two autocorrelation sample points at the receiver so that the Doppler shift estimation can be retrieved. Since the computation for solving the equation is formidable, the proposed algorithm has also been further simplified by using the optimal polynomial approximation to the zero order Bessel function of the first kind. Computer simulation demonstrates that the proposed algorithm can estimate the Doppler shift accurately within a wide range of Doppler shift.