An Estimate Of The Wcdma System Frequency Deviation And The Maximum Doppler Shift Method

In the digital mobile communication, with the effect of modulation, transmission channels and demodulation, the received signal ineluctably has some distortion. Frequncy offset is one of them. It mainly includes two parts: the frequency offset caused by the difference of the mobile equipment's transmitting frequency and the nodeB's receiving frequency; the frequency offset caused by the vehicle of the mobile equipment, which is called Doppler shift. Accurate Frequency offset estimation and compensation is of importance for demodulation. Estimation of Doppler spread width which is equal to the maximal Doppler Frequency is an important way to calculate the velocity of the mobile equipment.The ways of estimating the frequency offset and Doppler spread width in WCDMA system are studied in this paper. The estimation of frequency offset is based on pilot symbols and non-pilot symbols. This paper also discusses some parameters in the method and gives the way of compensation. To get the estimation method of Doppler spread width, we model the Rayleigh channel based on the conclusion of Gans'spectrum analysis based on Clarke model. And we utilize the relation of spectrum function and correlation function to give the way of estimating Doppler spread width. And we discuss some factors in this method.At last, the implement of the methods on DSP is refered. Based on the statistics, the performance of the methods is analyzed.