A time-frequency joint synchronization method and device in an OFDM system

Abstract

The invention discloses a time and frequency joint synchronization method and device in an OFDM system. In the OFDM system, according to a characteristic that an LFM signal converges after Radon-Wigner conversion and a peak position changes correspondingly due to time offset and frequency offset, the LFM signal is used as a training sequence, the peak position is detected, and the time offset and frequency offset are estimated and compensated at the same time. The method mainly comprises the following steps of selecting two LFM signals with reverse frequencies at a sending end and adding up the two LFM signals so as to be used as the training sequence; performing Radon-Wigner conversion on the received training sequence at a receiving end, and detecting actual peak position information; determining a center frequency variable of the two LFM signals; determining time offset and frequency offset in the system; and compensating an OFDM symbol according to the obtained time offset and frequency offset. The method and device have high synchronization performance, and can improve the estimation accuracy of the existing algorithm remarkably particularly at a low signal-to-noise ratio.

Description

technical field [0001] The invention relates to the field of digital communication, in particular to a time-frequency joint synchronization method and device in an OFDM system. Background technique [0002] A digital communication system is a system that uses digital signals to transmit information and is the basis of a modern communication network. The digital communication system has the advantages of strong anti-interference ability, high reliability, easy encryption and strong confidentiality, good flexibility, and equipment integration, etc. that the analog communication system does not have. But while there are many advantages, the digital communication system also has the problems of wide occupied frequency band and complex technical requirements, especially the high precision of synchronization technology. [0003] The most fundamental requirement and goal of digital communication is the reliable and high-speed transmission of signals in the channel. In order to mee...

AI Technical Summary

Problems solved by technology

Compared with the traditional synchronization method using training sequence correlation, this synchronization algorithm can calculate the time offset and integer multiple frequency offset at the same time, which improves the synchronization efficiency and overcomes the problem of low signal-to-noise ratio of FrFT on LFM signal detection performance. Therefore, it has a better synchronization effect than the FrFT-based time-frequency joint synchronization method at low signal-to-noise ratios, and improves the time-frequency synchronization accuracy

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