Indirect self-adaptive balancing method of shallow-sea underwater acoustic communication system

Abstract

The invention discloses an indirect self-adaptive equalization method of a shallow-sea underwater acoustic communication system to eliminate transmission intersymbol interference brought by a shallow-sea underwater acoustic channel with the time-varying and multi-diameter characteristics. The method comprises the following steps: designing a signal frame structure suitable for transmission in the shallow-sea underwater acoustic channel at a sending terminal; utilizing a frame head PN sequence to carry out rapid channel estimation and the initialization of equalizer tap coefficients at a receiving terminal; selecting a corresponding threshold according to the practical transmission environment to realize the decentralization of equalizer taps; and adopting an LMS algorithm with a variable step size to further reduce errors so as to better equalize frame body data. The invention enables an equalizer in the shallow-sea underwater acoustic communication system to have rapid convergence and lower hardware complexity, has good equalization effect on a sending signal after high-level modulation and can be effectively applied to the shallow-sea high-speed digital communication system.

Description

technical field [0001] The invention relates to an equalization method for a communication system, in particular to an adaptive equalization method for a shallow seawater acoustic communication system. Background technique [0002] In the shallow seawater acoustic communication system, due to the interaction between the sea surface and the submarine acoustic field, the shallow seawater acoustic channel often exhibits severe frequency-selective fading and time-varying characteristics. In addition to this, many other effects such as internal waves, reverberation, etc. are also responsible for unreliable communication performance. The multipath characteristic of the shallow sea acoustic channel will cause intersymbol interference (ISI), and the order of magnitude of its multipath spread is above milliseconds. Therefore, under the condition of high data transmission rate, the ISI generated after passing through the channel is very serious, which requires that equalization techn...

AI Technical Summary

Problems solved by technology

However, in practical applications, these methods only support low-order modulated transmission signals mapped by QPSK or 4QAM, and their performance deteriorates sharply in high-speed underwater communication systems with high-order modulation such as 64QAM.

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