A Differential Correlation Acquisition Method Adapted to the Environment with Frequency Offset and Low SNR

Abstract

The present invention relates to an acquisition method using unbiased differential correlation and coherent accumulation being applied to an environment with frequency offset and a low signal to noise ratio. The method comprise the following steps of segmenting a received signal according to a code length period, and associating a sequence obtained after segmentation with a corresponding local code so as to eliminate pseudo code information; performing M-order unbiased differential correlation on the sequence with pseudo code information eliminated so as to improve the signal to noise ratio of the sequence; performing coherent accumulation on a result after M-order correlated operation so as to obtain a peak value; and comparing the peak value with an adaptive threshold, and determining that if the peak value exceeds the adaptive threshold, confirmation is carried out again, and if the peak value still exceeds the threshold, the acquisition is right. According to the method, low signal to noise ratio based acquisition performance can be improved.

Description

technical field [0001] The invention relates to the technical field of wireless communication, in particular to an acquisition method using unbiased differential correlation and coherent accumulation, which is adapted to the environment with frequency deviation and low signal-to-noise ratio. Background technique [0002] Acquisition is a key technical issue in the field of wireless communication, and the acquisition performance determines the performance of the system to a large extent. At the same time, in consideration of low cost, ordinary crystal oscillators are generally used, and the frequency offset of transceivers can reach 40PPM. For traditional correlation capture, the existence of frequency offset will seriously attenuate the correlation peak and deteriorate the capture performance. Therefore, the acquisition algorithm for the low signal-to-noise ratio environment with frequency offset has become an indispensable key technology for wireless communication systems....

AI Technical Summary

Problems solved by technology

Among them, the traditional differential capture is simple to implement and can eliminate the influence of frequency offset, but with the increase of PN code and the decrease of signal-to-noise ratio, the capture sensitivity lost by differential processing is too much

The performance of the FFT-based capture algorithm is related to the number of FFT points. The overhead of resources is too large under low signal-to-noise ratio, and there is a fence effect, which has a great impact on the capture performance.

The two-dimensional search and acquisition algorithm using pseudo-code synchronization and frequency offset estimation is generally used in weak GPS signals, and the acquisition time is long, which is not suitable for DSSS application scenarios under low signal-to-noise ratio

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