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

An adaptive equalization, underwater acoustic communication technology, applied in transmission systems, baseband system components, shaping networks in transmitters/receivers, etc., can solve problems such as performance degradation

Inactive Publication Date: 2009-10-28
魏昕
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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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  • Indirect self-adaptive balancing method of shallow-sea underwater acoustic communication system
  • Indirect self-adaptive balancing method of shallow-sea underwater acoustic communication system
  • Indirect self-adaptive balancing method of shallow-sea underwater acoustic communication system

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Embodiment Construction

[0056] The technical solutions of the present invention will be further described below in conjunction with the drawings and embodiments.

[0057] 1. The signal frame structure of the sending end

[0058] At the sending end of the shallow sea acoustic communication system, after the bit stream to be sent undergoes error-correcting channel coding and constellation mapping, a symbol sequence is obtained, and these symbols are sent out in the form of a signal frame to form a data packet. A data packet consists of Composed of M signal frames, each signal frame consists of frame body and frame header, such as figure 1 shown. where frame body N B consists of symbols, with a length N known to both the sender and the receiver H The PN sequence is used as the frame header. Fast and accurate channel estimation and synchronization can be realized by utilizing the good correlation characteristics of PN sequences.

[0059] 2. Indirect adaptive equalization method

[0060] figure 2 ...

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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...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L25/03H04L25/02H04B1/707H04B13/02
Inventor 魏昕赵力余华邹采荣奚吉
Owner 魏昕
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