Frequency offset estimation method and device for LTE (Long Term Evolution) system

Abstract

The invention discloses a frequency offset estimation method for an LTE (Long Term Evolution) system. The frequency offset estimation method is used for frequency offset estimation in a severe channel environment and can effectively reduce the bit error rate. The method comprises the steps of carrying out cross-correlation operation on a received digital signal and a local primary synchronization signal and extracting a descending primary synchronization signal from a digital signal; carrying out frequency offset estimation on the descending primary synchronization signal and acquiring coarse frequency offset required by correction of the digital signal; performing frequency offset correction to the digital signal by use of the coarse frequency offset to obtain preliminarily corrected digital signal; extracting a cyclic prefix signal from the preliminarily corrected digital signal; performing frequency offset estimation to the cyclic prefix signal to obtain fine frequency offset required by correction of the digital signal; and carrying out frequency offset correction on the digital signal according to the coarse frequency offset and the fine frequency offset, and finally obtaining the corrected digital signal.

Description

technical field [0001] The present invention relates to the field of communication technologies, in particular to a frequency offset estimation method and device for Long Term Evolution (LTE). Background technique [0002] The downlink of the LTE system adopts the access method of Orthogonal Frequency Division Multiple Access, which has the advantages of high spectral efficiency, strong anti-multipath interference capability, and simple equalization, but the relatively increased symbol period makes the LTE system less sensitive to carrier offset than single carrier The system is more sensitive, and the cause of the carrier frequency deviation is mainly the difference between the carrier frequency of the transmitter and the local frequency of the receiver and the Doppler frequency shift caused by the high-speed movement of the terminal. Since the frequency offset can easily cause interference between subcarriers, which will greatly affect the correct demodulation of data, res...

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Problems solved by technology

[0002] The downlink of the LTE system adopts the access method of Orthogonal Frequency Division Multiple Access, which has the advantages of high spectral efficiency, strong anti-multipath interference capability, and simple equalization, but the relatively increased symbol period makes the LTE system less sensitive to carrier offset than single carrier The system is more sensitive, and the cause of the carrier frequency deviation is mainly the difference between the carrier frequency of the transmitter and the local frequency of the receiver and the Doppler frequency shift caused by the high-speed movement of the terminal

Since the frequency offset can easily cause interference between subcarriers, which will greatly affect the correct demodulation of data, resulting in an increase in the bit error rate, it is necessary to effectively measure and estimate the frequency offset in the LTE system , and then calibrate and track according to the measured values ​​so that the deviation between the transmitter and receiver is as small as possible

[0003] The main method for frequency offset estimation in the prior art is the frequency offset estimation algorithm based on reference signals. This algorithm performs frequency offset estimation through time-domain cross-correlation. The calculation complexity of this algorithm is moderate, but it is limited by the estimation function used. The frequency offset estimation performance of integer multiples is good, but the accuracy of frequency offset estimation of decimal multiples is poor in the presence of integer frequency offsets. Secondly, the algorithm also relies on reliable timing synchronization. When the channel environment is bad or timing synchronization deviation When it is large, the performance of frequency offset estimation will be severely degraded, which will affect the correct demodulation of data

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