Method and apparatus for estimating integer frequency bias

Abstract

The invention discloses a method and a device for estimating integer frequency offset; the method comprises the steps: fast Fourier transformation is carried out to a plurality of time-domain positions which receive signals and comprise timing synchronization positions so as to obtain multiple groups of frequency domain data; the frequency domain data are correlated with local pilot sequences respectively in the searching range of the integer frequency offset so as to obtain multiple groups of correlation values; peak search is carried out to the multiple groups of correlation values; and the integer frequency offset corresponding to the highest value among the correlation values is taken as the integer frequency offset estimation. With the adoption of the method and the device in the embodiment, a frequency domain correlation is carried out in a plurality of positions around the timing synchronization position, and the integer frequency offset corresponding to the highest value among the correlation values is taken as the integer frequency offset estimation, thereby increasing the accuracy of the integer frequency offset estimation and reducing the influence on the integer frequency offset estimation by unsatisfied timing synchronization.

Description

technical field [0001] The present invention relates to the communication field, in particular to an integer frequency offset estimation method and device. Background technique [0002] At present, the Zadoff-Chu sequence is more and more widely used in various OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) communication systems due to its good correlation characteristics, such as the LTE (3GPP Long Term Evolution, 3GPP Long Term Evolution Project) system Zadof-Chu is used as a synchronization signal in . In this type of mobile communication system, there is a problem that the user equipment UE (User Equipment) and the crystal oscillator of the base station cannot locate the same frequency accurately, so there is a frequency offset in the communication system, and the frequency offset will seriously affect the communication. system performance. Frequency offset in OFDM systems usually refers to normalized frequency offset, whi...

AI Technical Summary

Problems solved by technology

The integer frequency offset will cause the position of the subcarrier where the frequency domain data is located to shift. The size of the shift is equal to the size of the integer frequency offset. Therefore, the integer frequency offset must be accurately estimated and corrected, otherwise the OFDM communication system will not work properly.

[0003] In the process of implementing the present invention, the inventor found that in the prior art, the integer frequency offset estimation would be affected by the timing synchronization, because the actual timing synchronization position It is not always possible to be exactly at the ideal position t 0 , the synchronization position offset will cause the frequency domain data to rotate with the phase of the subcarrier. For the system using the Zadoff_Chu sequence as the frequency domain pilot, this phase rotation will cause the shift of the correlation peak, such as figure 1 As shown in the simulation results, set the integer frequency offset ε int = 0, the correlation peak of the ideal timing is at 0, and after a certain timing deviation exists, the correlation peak is at 5, obviously, the latter integer frequency offset estimation will be wrong

In addition, the correlation peak offset may be caused by integer frequency offset or non-ideal time synchronization, which cannot be distinguished by the existing integer frequency offset estimation method

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