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Method for estimating carrier, frequency shifts of orthogonal FDM communication system

A carrier frequency offset and multiplexing communication technology, which is applied in the direction of orthogonal multiplexing system, multiplexing communication, multi-carrier system, etc., can solve the problem of increasing the difficulty of system implementation, difficult ASIC implementation, large amount of calculation, etc. problem, to achieve the effect of easy implementation, small amount of calculation and good effect

Inactive Publication Date: 2004-02-04
SHANGHAI JIAO TONG UNIV
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Problems solved by technology

The frequency domain synchronization algorithm was proposed by Ferdinard Classen and Heinrich Meyr in the paper Frequency Synchronization Algorithms for OFDM Systems Suitable for Communication Over Frequency Selective Fading Channels (inProc.IEEE Veh.Technol.Conf., 1994, pp.1655-1659), the method mainly It is a method that uses repeated sequences combined with DFT to estimate the frequency error. It can improve the estimation range of the frequency offset, but it requires the pre-processing of the FFT data. These processes will actually cause additional errors, resulting in actual processing delays, and also Increased the difficulty of system implementation
The time-domain frequency synchronization method was proposed by Paul HMoose in the paper A Technique for Orthogonal Frequency Division Multiplexing Frequency Offset Correction (IEEE Trans.Commun., vol.42, pp.2908-2914, Oct.1994), which is mainly based on the maximum Likelihood (MLE, Maximum LikelihoodEstimation) frequency offset estimation algorithm, but it has a large amount of calculation, low precision, and is not easy to implement in the system ASIC

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  • Method for estimating carrier, frequency shifts of orthogonal FDM communication system
  • Method for estimating carrier, frequency shifts of orthogonal FDM communication system
  • Method for estimating carrier, frequency shifts of orthogonal FDM communication system

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Embodiment

[0032] Embodiment: The method of the present invention is applied to OFDM wireless local area network.

[0033] The application of the present invention in an OFDM wireless local area network transmitting and receiving system is shown in FIG. 3 . After the data at the transmitter is convolutionally encoded, interleaved, and modulated, a specially designed training sequence is first added to the system frame to estimate the frequency offset. Here, since the data sampling point length to be sent in the system frame is 64, the sampling point length of each A training sequence added is 1 4 × 64 = 16 , there are 10 training sequences for class A. According to the relationship between the lengths of training sequences A and B, two training sequences of type B are added, the length of sampling points of each training sequence of type B is 64, and the cyclic prefix of training sequences of type B is...

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Abstract

A estimating method of OFDM communication system carrier frequency excursion, in original place of systems frame adds two training sequence that were designed especially, using the result of cross correlation of class A training sequence estimates original value of frequency excursion, namely to make rough estimation of frequency excursion, then using class B makes autocorrelation, gained frequency deviation signal was estimated precisely in small scale, namely to make frequency excursion precise estimation, then make two estimating value combined to get precise value of system frequency excursion, finally control numerical control oscillator to produce rectify value of system frequency excursion, and put it to multiply with time domain data to make compensation of frequency excursion.

Description

Technical field: [0001] The invention relates to a method for estimating carrier frequency offset in an orthogonal frequency division multiplexing communication system, which is a method for estimating and compensating carrier frequency offset, and belongs to the field of digital communication. Background technique: [0002] Orthogonal Frequency Division Multiplexing (OFDM) is a data modulation method that converts high-speed serial data into low-speed parallel data, and modulates the parallel data with multiple mutually orthogonal subcarriers. Although sub-carrier spectrum overlaps, since each sub-carrier is orthogonal, there is no interference between carriers, so spectrum utilization efficiency can be effectively improved. As an emerging multi-carrier modulation technology, OFDM has strong anti-multipath fading and frequency selective fading characteristics, and has been used in asymmetric digital subscriber line (ADSL), digital television broadcasting (DVB), wireless loc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04J11/00H04L27/32
Inventor 周跃峰许婵媛陈柏南胡亮亮周军
Owner SHANGHAI JIAO TONG UNIV
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