Method for realizing frequency synchronization in orthogonal FDM system

Abstract

A method for realizing frequency synchronization in orthogonal FDM system features the combination of the fraction in orthogonal FDM system features the combination of the fraction multiplying synchronization with integer multiplying one, and includes such steps as frequency tracking before FFT, estimating fraction multiplying frequency shift, preliminary correcting, then capturing the frequency, estimating integer multiplying frequency shift, and fine frequency correction by discrete Fourier transformation and serial-parallel conversion. Its advantage is high synchronization precision.

Description

Technical field: [0001] The invention relates to a method for realizing frequency synchronization in an OFDM system, which is mainly applied to a new generation cellular mobile communication system, a wireless local area network, and a wireless and wired transmission system based on the OFDM system. Background technique: [0002] The concept of using parallel data transmission and frequency division multiplexing was proposed in the mid-1960s, in order to make full use of the effective bandwidth, use overlapping sub-channels to avoid the use of high-speed equalizers, resist impulse noise and multipath effects. It was first applied in military communication, and its characteristic is that the subcarriers are orthogonal to each other. We generally call this system Orthogonal Frequency Division Multiplexing, or OFDM for short. [0003] In an OFDM system, there is a carrier frequency offset between the transmitter and receiver due to the mismatch between the transmitter and rec...

AI Technical Summary

Problems solved by technology

[0005] The first type of method uses special synchronization blocks to estimate the frequency offset, and can get good results. However, this method needs to insert synchronization blocks, which reduces the frequency band utilization. In this case, the number of synchronization blocks is required to be much smaller than The amount of data is still a little insufficient, the synchronization time is relatively long, and the algorithm is complicated

[0006] The second type of method has high spectrum utilization, but poor synchronization performance

[0007] The third type of method uses the characteristics of the signal itself in the OFDM system to synchronize. The algorithm is relatively simple, but the accuracy is relatively low.

This method can accurately estimate the integer multiple frequency offset, but its disadvantage is that the estimation range is limited

And the frequency acquisition algorithm is relatively complex

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