Carrier frequency offset estimation method, device and system

A technology of frequency offset estimation and carrier frequency offset, applied in the field of communication, can solve the problem of inability to take into account the accuracy of carrier frequency offset estimation and the acquisition range of frequency offset, and achieve the effect of ensuring accuracy and reliability

Active Publication Date: 2012-07-25
OMNIVISION TECH (SHANGHAI) CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The embodiment of the present invention provides a carrier frequency offset estimation method, device and system to solve the problem that the accuracy of carrier frequency offset estimation and frequency offset acquisition range cannot be considered in the prior art

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  • Carrier frequency offset estimation method, device and system
  • Carrier frequency offset estimation method, device and system
  • Carrier frequency offset estimation method, device and system

Examples

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Embodiment 1

[0039] An embodiment of the present invention provides a method for calculating a carrier frequency, including:

[0040] 101. The correlator receives the preamble sequence r n , with the locally stored Barker sequence b of the correlator n Carry out related operations, and the calculation result is c n ;

[0041] In the embodiment of the present invention, the received preamble sequence can be either a baseband signal or an oversampled signal, and the correlation sequence c n The number of samples between peaks is related to the sampling rate, but in any case, the transmission rate F of each preamble symbol s = 1MHz is fixed, that is to say the correlation sequence c n The peak value of is repeated at a rate of 1MHz, so the sampling interval corresponding to the peak position is T s =1 / F s , the received preamble sequence is denoted as r n , the local Barker sequence is denoted as b n , the Barker code correlation operation can be expressed as Where L is the length o...

Embodiment 2

[0077] In the embodiment of the present invention, two frequency offset estimation devices are used, that is, a two-stage frequency offset estimation method is selected, specifically:

[0078] The delay parameter D of the first stage is selected as 1, which can ensure the capture range of the frequency offset, and the delay parameter D of the second stage is selected as 20, which can improve the accuracy of frequency offset estimation.

[0079] When the delay of the first-stage frequency offset estimation module is selected as 1, since the maximum frequency offset that the 802.11b system needs to support is ±125KHz, two adjacent correlation peaks x can be calculated n+1 and x n The phase difference between them is at most 45 degrees, so y n The energy of the real part of the sequence must be greater than the energy of the imaginary part, so you can directly use y n The real part of the modulation sequence is used to determine the modulation sequence to estimate the BPSK modu...

Embodiment 3

[0088] The embodiment of the present invention also provides a carrier frequency offset estimation system, including:

[0089] Correlator 301, peak extraction module 302, first frequency offset estimation module 303, second frequency offset estimation module 304 and frequency offset combination module 305, wherein:

[0090] Correlator 301, used to receive the preamble sequence r n , with the locally stored Barker sequence b of the correlator n Carry out related operations, the result is c n ;

[0091] Peak extraction module 302, used for said c n Take the peak value of every L points in the , and record the result as x n , the L is the length of the Barker sequence corresponding to the sampling rate;

[0092] The first frequency offset estimation module 303 is configured to receive x n , calculate the corresponding estimated value of carrier frequency offset;

[0093] The second frequency offset estimation module 304 is used to receive x n , calculate the corresponding...

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Abstract

The embodiment of the invention provides a carrier frequency offset estimation method, a device and a system. The method comprises the following steps of: receiving a leader sequence rn by a correlator, and performing correlation operation with a Barker sequence (bn) which is locally saved in the correlator to get a result of cn; taking a peak value of every L points in the cn, and recording the result as xn, wherein L is the length of the Barker sequence, which corresponds to sampling rate; performing frequency offset estimation on the xn through at least two frequency offset estimation devices, and figuring out corresponding carrier frequency offset estimated values, wherein the values of time delay parameters D in the frequency offset estimation devices are different; and inputting the results output by the at least two frequency offset estimation devices into a frequency offset combination module, and figuring out a final carrier frequency offset estimated value. By adopting the method provided by the embodiment of the invention, the precision in frequency estimation can be realized and the frequency offset capture range can be ensured.

Description

technical field [0001] The present invention relates to the communication field, in particular to a carrier frequency offset estimation method, device and system. Background technique [0002] The frame structure of wireless local area network 802.11b includes three parts: preamble sequence, frame header sequence and data sequence. Since the wireless local area network transmits information in bursts, the receiver must complete various synchronizations of the receiver during the reception of the preamble sequence. Carrier frequency estimation is a very important step in carrier synchronization. Since the wireless local area network standard stipulates that the stability of the crystal oscillator should be controlled within ±25ppm, it can be calculated that the receiver needs to have the ability to estimate the carrier frequency deviation of ±125KHz at most. [0003] Wireless LAN 802.11b needs to be able to work in extremely harsh environments. For example, when the transmis...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26
CPCH04L27/2671H04L27/2657H04L27/2675H04L27/26H04L27/2613
Inventor 张赟
Owner OMNIVISION TECH (SHANGHAI) CO LTD
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