OFDM underwater sound time-varying Doppler frequency offset estimation method based on non-uniform no-load wave

Abstract

The invention relates to an OFDM underwater sound time-varying Doppler frequency offset estimation method based on non-uniform empty subcarriers, and the method comprises the following steps: 1) after a receiving end carries out frequency mixing, filtering, down-sampling, synchronization and OFDM frame Doppler estimation on OFDM received signals, solving a spectral function by utilizing non-uniform empty subcarrier signals of the receiving end and adopting a multiple signal classification, namely a MUSIC method; 2) according to the solved spectral function, adopting a simulated genetic algorithm to quickly solve a spectral function extreme solution based on the non-uniform no-load wave, obtaining an individual evaluation basis by calculating individual fitness in the population, and adopting gene operations of copying, crossing and mutation to obtain a new population with optimized fitness until iteration converges to a final result. According to the method, no-load wave placement is more arbitrary and flexible, joint optimal estimation of multiple symbol time-varying Doppler factors can be directly obtained, and compared with a spectrum peak search algorithm, the calculation amount is smaller, and the search efficiency is higher.

Description

technical field [0001] The invention belongs to the field of underwater acoustic communication, in particular to an OFDM underwater acoustic time-varying Doppler frequency offset estimation method based on a non-uniform empty carrier. Background technique [0002] Orthogonal frequency division multiplexing (OFDM) technology is widely used in underwater acoustic communication systems because of its strong anti-channel fading characteristics and high spectrum utilization. Unlike the radar system, the Doppler frequency shift of sonar is much greater than that of radar because the propagation speed of sound waves is much smaller than that of electromagnetic waves. Therefore, in order to achieve correct tracking and decoding, Doppler estimation and compensation technology has always been a key part of OFDM underwater acoustic communication system. [0003] The patent with publication number CN105282082A discloses a Doppler estimation method based on the combination of copy corre...

AI Technical Summary

Problems solved by technology

The above two methods use the Doppler estimation method based on the pilot frequency, the single frequency signal and the cyclic prefix respectively. Compared with the Doppler estimation method based on the empty subcarrier, the above two methods waste the transmission energy and the estimation accuracy is not high.

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