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Passive time-reversal underwater acoustic communication method based on indirect channel function tracking

A channel function, underwater acoustic communication technology, applied to the shaping network in the transmitter/receiver, baseband system components, etc. Small amount of calculation, the effect of reducing the order

Active Publication Date: 2014-04-02
ZHEJIANG UNIV
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  • Description
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Problems solved by technology

However, the time-varying nature of the underwater acoustic channel makes the performance of time-reversal communication significantly degraded, and it is even impossible to achieve communication

Method used

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  • Passive time-reversal underwater acoustic communication method based on indirect channel function tracking
  • Passive time-reversal underwater acoustic communication method based on indirect channel function tracking
  • Passive time-reversal underwater acoustic communication method based on indirect channel function tracking

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Embodiment Construction

[0014] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0015] The transmit signal structure is as figure 1 As shown, it consists of pre-chirp signal, training sequence, data and post-chirp signal. Among them, the selection of the chirp signal satisfies BT>100, (B is its bandwidth, T is its pulse time width).

[0016] Denote the transmitted signal as s(t), then the signal received by the i-th array element can be expressed as

[0017] r i ( t ) = s ( t ) ⊗ h i ( t ) - - - ( 1 )

[0018] Among them, h i (t) is the channel impulse response from the transmitting source to the i-th array element; Re...

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Abstract

The invention discloses a passive time-reversal underwater acoustic communication method based on indirect channel function tracking. The method comprises the following steps: firstly, using a training sequence which receives a signal to estimate a channel time delay, namely a Doppler spread function; analyzing the Doppler extension phenomenon to implement indirect channel function modeling, then carrying out Doppler compensation on the received signal of each array element, carrying out time reversal processing on channel estimation obtained by an indirect channel function estimated by the training sequence and the signal compensated by Doppler, estimating and tracking the indirect channel function by using a Kalman / extended Kalman filter, judging whether a Doppler compensation factor and the channel estimation are updated or not according to a normalized amplitude of the estimated indirect channel function, and finally, recovering a transmitted symbol from the signal processed by time-reversal by utilizing a decision feedback equalizer which is less than ten orders. The method uses the tracking for the indirect channel function to confront the performance reduction of passive time-reversal communication caused by environment time-varying, thereby realizing the high-speed and stable uplink underwater acoustic communication in a rapidly changing environment of an underwater acoustic channel.

Description

technical field [0001] The invention relates to the field of underwater acoustic communication, and mainly relates to a passive time-reverse underwater acoustic communication method based on indirect channel function tracking. Background technique [0002] Due to the rich dynamic process in the water body, the effect of the acoustic boundary, the refraction caused by the gradient of the sound velocity profile in the water body, and the scattering of particles, the underwater acoustic channel often manifests as serious multipath delay spread, Doppler frequency shift spread and so on. The fast time-varying characteristics cause severe intersymbol interference. Traditional communication technology uses equalization technology to combat inter-symbol interference caused by multipath. For underwater acoustic channels with severe delay expansion, the order of traditional equalizers is on the order of hundreds, and the amount of calculation is huge. Time counter technology is an ef...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L25/02H04L25/03
Inventor 金丽玲夏梦璐曾文俊余子斌徐文
Owner ZHEJIANG UNIV
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