Carrier frequency synchronous circuit and method of OFDM (Orthogonal Frequency Division Multiplexing) system

Abstract

The invention discloses a carrier frequency synchronous circuit and method of an OFDM (Orthogonal Frequency Division Multiplexing) system. The carrier frequency synchronous circuit comprises a decimal fraction frequency offset estimation circuit, a decimal fraction frequency offset compensation circuit, an integer frequency offset estimation circuit, an integer frequency offset compensation circuit and other circuits; correspondingly, the method comprises the following steps of decimal fraction frequency offset estimation, decimal fraction frequency offset compensation, integer frequency offset estimation and integer frequency offset compensation; a cross-correlation value of two adjacent synchronous sequences to be sampled of a frequency domain is subjected to normalization treatment to obtain a decimal fraction frequency offset estimation value, and decimal fraction frequency offset compensation correction is carried out by utilizing the estimation value; then, the high energy carrier sign bit of each OFDM sign subjected to fast Fourier transform (FFT) treatment is subjected to self-correlation computation, the self-correlation of a plurality of OFDM signs is subjected to summation computation to obtain an integer frequency offset estimation value, and then integer frequency offset compensation is carried out according to the integer frequency offset estimation value. By adopting the synchronous circuit and method, the computational burden can be reduced, the influence of noise to frequency offset estimation can be lowered, and low-power equipment is favorably designed and realized.

Description

technical field [0001] The invention relates to communication signal modulation technology, in particular to a carrier frequency synchronization circuit and method of an Orthogonal Frequency Division Multiplexing (OFDM) system. Background technique [0002] OFDM technology is widely used in a variety of high-speed data access systems due to its ability to resist multipath interference and frequency selective fading, such as wireless local area network, high-speed digital subscriber loop, asymmetric digital subscriber loop, digital audio broadcasting , digital video broadcasting and high-definition digital television and other occasions. Now many international and domestic standards have adopted OFDM technology as the transmission means of the physical layer. [0003] Since OFDM technology can better solve problems such as multipath interference and broadband transmission in high-speed communication systems, this technology has become a candidate for the fourth generation mo...

AI Technical Summary

Problems solved by technology

But there is a problem: since OFDM technology relies on the orthogonality of frequency, once its orthogonality is destroyed, the bit error rate of the system will increase sharply, which is also a major defect in the application of OFDM technology

[0010] To sum up, the decimal and integer frequency offset estimation methods in the existing OFDM system carrier frequency synchronization methods are greatly affected by interference such as noise and multipath fading phenomena, or have a large amount of calculation, so they are not suitable for application in demanding applications. Flaws in Devices for Low Complexity Computing

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