Research On The Technology Of The Doppler Shift Estimation In The High Dynamic Environment

In high dynamic circumstances, Doppler shifts are from several tens kHz to more than one hundred kHz, due to high velocity between the receiver and the transmitter. The communication is a challenging problem because of large Doppler shifts. The primary goal of this paper is to find efficient and precise methods to estimate Doppler shifts, which is also a pre-requisite problem in mobile communication research. Since the precision of Doppler shift estimation will affect the performance of receivers. It is important to investigate the Doppler shift scheme with improved accuracy.Firstly, the character of wireless channel is introduced briefly, especially its Doppler effect. Then, the influence of Doppler shift is analyzed in high dynamic circumstances, which is mainly about the signal to noise ratio of matched filter and the demodulation of differentially phase-modulated signal. Furthermore, the principle of Doppler shift estimation is studied, which is mainly discussed in the situation of low signal to noise ratio and high dynamic environment. Finally, several Doppler shift estimation methods in high dynamic environment are studied, including the approximate maximum likelihood estimation (MLE) method, the extended Kalman filter (EKF) estimation method, the cross-product frequency (CPF) estimation method and the transform domain estimation (FFT) method, A improved transform estimation method based on quadratic interpolation is proposed in this thesis, followed by a method based on time domain estimation and transform domain estimation. These methods are simulated and have more accurate estimation of Doppler shift.