Method for estimating and correcting frequency shift and apparatus thereof

Abstract

This invention relates to a wireless communication technology and discloses frequency offset estimation and a correction method and its device, which designs a certain interval frequency offset before and after the frequency-off set estimation value to mix the pilot frequency symbols with the two frequencies separately and carry out coherent accumulation to get energies to take the deviation of the two energies as the measure of the system residual frequency offset. The coherent accumulation energy of the pilot symbols reaches to the maximum after correcting the frequency offset with the feedback regulation method so as to get the largest likelihood estimation.

Description

technical field [0001] The invention relates to wireless communication technology, in particular to wideband code division multiple access technology. Background technique [0002] In electronic communication, especially mobile communication, more and more coherent demodulation methods are used to improve the performance of the communication system. For example, in the Wideband Code Division Multiple Access (WCDMA) mobile communication system, which is one of the 3rd Generation mobile communication (3G for short) standards, the up and down between the base station and the mobile station Both channels adopt the signal detection method of coherent demodulation. [0003] One of the prerequisites for coherent demodulation is that the demodulated carrier at the receiving end must have the same frequency and phase as the modulating carrier at the sending end. However, in practical applications, due to various reasons, the demodulated carrier at the receiving end cannot be guaran...

AI Technical Summary

Problems solved by technology

[0027] In actual application, the above scheme has the following problems: For the cross product frequency discrimination method, its algorithm complexity is high, the estimation accuracy is low, the dynamic range is small, and it cannot reach Statistically the best performance; for the Fourier transform method, the algorithm complexity is too high, and it is difficult to implement; using these frequency offset estimation methods for frequency offset correction will bring the same problem, low precision and high complexity, resulting in the entire communication System performance drops

[0028]The main reason for this situation is that the cross-product frequency discrimination method adopts the method of calculating the phase angle by delay cross-product, which has a large amount of calculation and is affected by the phase period However, the Fourier transform method uses Fourier transform for spectrum analysis, which inevitably brings high complexity; thirdly, the existing frequency offset estimation methods do not start from the evaluation criteria with the best statistical significance, so they cannot reach the statistically optimal good estimation performance

Images