OFDM (Orthogonal Frequency Division Multiplexing) precise timing synchronous method based on Zadoff-Chu sequence

Abstract

The invention discloses an OFDM (Orthogonal Frequency Division Multiplexing) precise timing synchronous method based on a Zadoff-Chu sequence, which belongs to the technical field of communication and mainly aims at solving the problem of timing deviation caused by the fact that a path with the maximum energy in a multi-path fading channel of an orthogonal frequency division multiplexing system is not a first path. Channel impulse response is estimated through Zadoff-Chu sequence correlation, and a self-adaptive threshold detection algorithm for withstanding residual frequency deviation is established, then the achieving time of the first path is accurately judged, moreover the self-adaptive threshold is modified aiming at the problem that the false alarm probability is increased because of the residual frequency deviation, and verification shows that in a high speed moving multi-path environment, the algorithm detection probability is high, the mean square error is small, the detection probability can be greater than 99% in an SUI-3 channel when the signal to noise ratio is greater than 3dB, and then the method can be applied to a wideband OFDM communication system in the high speed moving environment.

Description

technical field [0001] The invention relates to OFDM system timing synchronization technology, in particular to a Zadoff-Chu sequence-based OFDM precise timing synchronization method, which belongs to the field of communication technology. Background technique [0002] OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing technology) is widely used in high-speed wireless transmission systems due to its high spectrum utilization rate and strong anti-multipath fading capability. Timing synchronization is one of the key issues in OFDM systems, and there have been a lot of researches on it. [0003] In a multipath environment, many people have proposed a timing synchronization algorithm based on energy detection, but the timing point obtained by it will be offset by the influence of the maximum energy path, and the arrival time of the first path cannot be accurately detected, resulting in Performance degradation of channel estimation algor...

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Problems solved by technology

Literature [3] estimates the timing offset according to the cyclic right shift characteristic of the channel impulse response, but the algorithm needs to perform two fast Fourier transforms, the implementation complexity is high, and there is a plateau phenomenon in the timing offset estimation peak

Literature [4] adopts Constant Envelope Zero Auto-Correlation (CAZAC) training sequence, which has high multipath resolution, and detects the arrival time of the first path according to the adaptive threshold, but ignores the frequency offset Effect of CAZAC sequence relatedness

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