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Multicarrier underwater acoustic communication method

An underwater acoustic communication, multi-carrier technology, applied in the field of communication, can solve problems such as orthogonal characteristic deterioration, signal-to-noise ratio decline, frequency offset and noise sensitivity, etc., to achieve the effect of improving transmission efficiency and frequency band utilization.

Inactive Publication Date: 2010-07-07
HARBIN ENG UNIV
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  • Abstract
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AI Technical Summary

Problems solved by technology

[0004] OFDM technology has disadvantages, mainly sensitive to frequency offset and noise
The method of OFDM technology to distinguish each sub-channel is to use the strict orthogonality between each sub-carrier, each of which is a single-frequency signal, frequency offset and noise will deteriorate the orthogonality between each sub-carrier, only 1% frequency deviation will reduce the signal-to-noise ratio by 30dB

Method used

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  • Multicarrier underwater acoustic communication method
  • Multicarrier underwater acoustic communication method
  • Multicarrier underwater acoustic communication method

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Embodiment Construction

[0046] The present invention is described in more detail below in conjunction with accompanying drawing example:

[0047] For baseband subcarrier modulation, the baseband multi-carrier modulation / demodulation formula is:

[0048] s=F -α x (1)

[0049] and

[0050] y=F αr (2)

[0051] where s = [s(0), s(1), ... s(N-1)] T and r = [r(0), r(1), ... r(N-1)] T is the data vector and the received vector to be demodulated, F -α and F α are discrete inverse fractional Fourier transform matrix and discrete fractional Fourier transform matrix respectively.

[0052] In view of the limited bandwidth of the underwater acoustic channel, in order to improve the frequency band utilization, the present invention proposes that the sub-carriers are sub-carrier pairs with positive and negative FM slopes. There are 2K subcarriers, K subcarriers are positive modulation frequency, K subcarriers are negative modulation frequency, and the frequency of each subcarrier is:

[0053] ...

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Abstract

The invention provides a multicarrier underwater acoustic communication method. The method comprises the following steps of: firstly modulating a base band subcarrier by utilizing a scattering inverse fractional order Fourier transform at a receiving terminal, wherein the plus-minus frequency subcarriers occurring in pair named as inter-modulation, secondly performing quadrature modulation on a real part and a virtual part of a base band signal so as to modulate a base band compound signal to be high frequency transmission, performing quadrature demodulation, rebuilding the base band compound signal, balancing anti-multipath diversity reception in time domain by using a Rake receiver, and balancing the decision feedback of the received signal in a fractional order Fourier transform domain. The frequency band of the invention is doubled, the transmission efficiency is high and the multipath diversity reception is resisted.

Description

technical field [0001] The present invention relates to a communication method, in particular to an underwater acoustic communication method. Background technique [0002] The underwater acoustic channel is a very complex time-space-frequency channel, and its main characteristics are complexity, variability, strong multi-path and limited bandwidth. Acoustic propagation loss and seawater absorption loss greatly limit the bandwidth of the underwater acoustic channel. The existence of multipath effects in the ocean underwater acoustic channel causes distortion of the received signal and serious intersymbol interference, which brings huge challenges to the design of the underwater acoustic communication system. difficulty. [0003] OFDM (Orthogonal Frequency Division Multiplexing) technology is actually a type of MCM (Multi-Carrier Modulation, multi-carrier modulation). The main idea is to divide the channel into several orthogonal sub-channels, convert high-speed data signals...

Claims

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Application Information

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IPC IPC(8): H04L27/26H04B13/02
Inventor 王逸林陈韵蔡平
Owner HARBIN ENG UNIV
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