Doppler factor estimation and compensation method of mobile underwater acoustic communication

Abstract

The invention discloses a Doppler factor estimation and compensation method of mobile underwater acoustic communication, related to underwater acoustic communication. The Doppler factor estimation andcompensation method of the mobile underwater acoustic communication comprises the following steps: 1) large scale Doppler estimation and compensation; 2) residual Doppler estimation and compensation;and 3) Doppler phase rotation compensation. In order to accurately and efficiently estimate the Doppler factor in the mobile underwater acoustic communication environment, overcome the more obvious Doppler effect compared with the terrestrial radio channel and eliminate the adverse effects on the underwater acoustic OFDM communication system of the Doppler effect, a Doppler factor estimation andcompensation method of the mobile underwater acoustic communication considering both the accuracy and the computationcomplexity is needed. Because the estimation is carried out in the frequency domainand aims at the characteristics of the underwater acoustic channel, the Doppler factor estimation and compensation method of the mobile underwater acoustic communication, especially the Doppler factor estimation and compensation method applied to the mobile underwater acoustic OFDM system is more suitable for the fast changing mobile underwater acoustic channel based on the traditional Doppler estimation and compensation. The estimation accuracy is high; and meanwhile, the computation complexity is reduced appropriately, therefore, the practicability is excellent.

Description

technical field [0001] The invention relates to the field of underwater acoustic communication, in particular to a Doppler factor estimation and compensation method for mobile underwater acoustic communication. Background technique [0002] As an important carrier of ocean detection and underwater acoustic communication, Unmanned Underwater Vehicle (UUV) has become a research hotspot in the field of ocean engineering in various countries. UUV has the characteristics of intelligence, concealment, mobility, economy, etc., and is light in weight, small in size, easy to use, and has broad economic and industrial value. [1] . The use of UUV for mobile underwater acoustic communication during high-speed movement has become one of the high-tech countries in the world that cover marine technology and information technology. [0003] Different from radio communication on land, the propagation velocity of sound waves under water is much smaller than that of electromagnetic waves. Th...

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Problems solved by technology

For example, in the published patent literature, a Doppler estimation method based on the combination of copy correlation and empty subcarriers with the publication number CN105282082A proposes to insert a chirp signal at the beginning and end of each frame signal to estimate the overall Doppler factor. This method only According to the overall Doppler extension of the data frame, it is difficult to accurately estimate the Doppler factor; the public number is CN104901718A based on the Doppler estimation method based on direct sequence spread spectrum signal carrier frequency measurement, based on direct sequence spread spectrum signal Measure the frequency value of the despread signal, compare the estimated frequency value and the original carrier frequency value to estimate the Doppler factor; the publication number is CN103618686A Accurate estimation method of underwater acoustic OFDM Doppler factor, design a prefix with cyclic prefix The OFDM frame of synchronous code and single-frequency signal is carried out Doppler estimation to the received signal; Publication number is CN102916922A document " underwater acoustic OFDM self-adaptive search Doppler compensation method " adopts CW (ContinuesWave) single-frequency signal as training sequence Rough measurement of Doppler frequency offset factor, using FFT to compensate for Doppler frequency offset

The above schemes all estimate the overall Doppler factor of the received signal through the synchronization signal or the self-circulation sequence. In the environment of the underwater acoustic channel with strong time variation, only the Doppler factor factor estimated value to compensate for the Doppler spread of subsequent OFDM data symbols, and its estimation accuracy is difficult to guarantee

The above method cannot accurately estimate the Doppler factor of each OFDM symbol, so it cannot achieve the effect of accurately demodulating the signal

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