	US 11,902,409 B2
	Frequency offset estimation method, device, communication device and storage medium
Bin Qian, Sichuan (CN); and Bo Liu, Sichuan (CN)
Assigned to CHENGDU CORESAT TECHNOLOGY CO., LTD, Sichuan (CN); and WUXI CORESAT TECHNOLOGY CO., LTD, Jiangsu (CN)
Filed by Chengdu Coresat Technology Co., Ltd, Sichuan (CN); and Wuxi Coresat Technology Co., Ltd, Suzhou (CN)
Filed on Apr. 29, 2022, as Appl. No. 17/733,501.
Claims priority of application No. 202110469871.8 (CN), filed on Apr. 29, 2021.
Prior Publication US 2022/0376883 A1, Nov. 24, 2022
Int. Cl. H04L 7/00 (2006.01); H04L 27/00 (2006.01)

CPC H04L 7/007 (2013.01) [H04L 27/0014 (2013.01); H04L 2027/0026 (2013.01)]

6 Claims

1. A frequency offset estimation method, applicable to a signal receiving end, wherein the signal receiving end is in communication with a signal sending end, and the method comprises steps of;

acquiring a main peak and a secondary peak of a PRACH signal when detecting that an access signal is in the PRACH signal sent by the signal sending end, wherein the PRACH signal is composed of a preset number of identical leader sequences;

calculating a ratio of a peak value of the main peak to a peak value of the secondary peak;

determining a first frequency offset according to the ratio and a preset subcarrier interval;

performing a frequency offset compensation on the PRACH signal according to the first frequency offset, to obtain a compensation sequence after the frequency offset compensation;

calculating a frequency offset between the compensation sequence and the leader sequences, to obtain a second frequency offset, so as to estimate a time delay of the access signal according to the second frequency offset;

acquiring a position of the main peak;

estimating a time delay of the access signal according to the position of the main peak and the second frequency offset, wherein according to a main peak point m′ and a number l of folds in integral folds of the frequency offset, a time delay position k is derived by calculation using a following formula, the access signal is expressed as:

a correlation peak is expressed as:

wherein if the number of folds of the frequency offset is not an integer, the peak point of the above formula m′=k, and the searched peak position m′ is a user time delay k; and if the number of folds of the frequency offset is an integer, the main peak point m′ and an actual time delay point k satisfy MOD(μ′l+κ,N)=m′,

wherein r(n) is the access signal, Δε is a frequency offset of the signal, Δε=Δf/f_s, f_sis a sampling rate, Δf is a frequency offset,

w(n) is noise with a mean value of 0 and a variance of a σ², μ is a root value, k represents an index value of a ZC sequence, N represents a length of a time domain sequence, n represents an index of the time domain sequence, and μ′ is dual to the root value^μ.