Double-expansion underwater acoustic channel doppler diversity communication method based on basis expansion model

Abstract

The invention provides a double-expansion underwater acoustic channel doppler diversity communication method based on a basis expansion model. In the method, zero padding suffix repetition code is used on a transmitting terminal, a base elimination algorithm is used on a receiving terminal, a time-varying double-expansion fading channel is decomposed into a time-invariant frequency selective fading component channel set. Then, doppler diversity gain is collected through a multichannel decision feedback equalizer, and intersymbol interference is resisted, and combined with a phase-lock loop, residual doppler distortion is tracked. The underwater acoustic communication scheme uses doppler which is usually seen as harmful component in conventional receiver design as a diversity gain source, effectively improves output signal to noise ratio of the receiver, and reduces error rate of a system. The multichannel decision feedback equalizer is used to reduce dependency on channel estimation of the receiver, and prevents large-matrix inverse operation which is relatively high in computation complexity.

Description

technical field [0001] The invention relates to a communication method for time-varying multipath underwater acoustic channels, in particular to a Doppler diversity communication method based on a base extension model. Background technique [0002] With the wide application of underwater communication in submarine oil exploration, marine environment monitoring and marine disaster rescue, the demand for data rate and reliability of underwater acoustic communication is gradually increasing. However, the transmission rate of underwater acoustic waves is 5 orders of magnitude lower than that of wireless communication. The channel is a double-spread channel with superimposed multipath delay spread and Doppler spread, which is considered to be one of the most complicated wireless channels at present. [0003] There are currently two processing methods for this dual extended channel. The first one models the Doppler effect as a carrier frequency offset, and uses a phase-locked lo...

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Problems solved by technology

However, for the actual time-varying underwater acoustic channel, modeling as carrier frequency offset or the same Doppler factor for each path is too ideal: among them, when using the method of modeling as carrier frequency offset, due to the underwater environment The time variation is large, and the position of underwater nodes is unstable, resulting in a high bit error rate and large inter-carrier interference in this method; when using the same Doppler factor method for each path, due to the underwater environment, especially the ocean environment is an isotropic Heterosexuality, the actual paths are different, resulting in a large error when the same factor is used for compensation

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