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

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...

AI Technical Summary

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

Images