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Underwater Acoustic Ofdm Decision Quadratic Channel Equalization Method

An equalization method and sub-channel technology, applied to the shaping network, electrical components, transmission system and other directions in the transmitter/receiver, can solve the problems of interpolation error, poor real-time tracking of time-varying channels, etc., so as to reduce the interpolation error and improve the Channel estimation accuracy, the effect of ensuring accuracy

Inactive Publication Date: 2011-12-28
HARBIN ENG UNIV
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Problems solved by technology

Block pilot inserts complete OFDM symbols (known) at certain intervals in the time domain, and can directly estimate the complete channel frequency response without interpolation, and then equalize other data symbols, but the real-time tracking for time-varying channels is poor; The pilot frequency is evenly distributed in each OFDM symbol, and the channel frequency response of the data subcarrier position is obtained by interpolating the channel frequency response of the pilot position, which can effectively track the channel time variation, but there is an interpolation error

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  • Underwater Acoustic Ofdm Decision Quadratic Channel Equalization Method
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  • Underwater Acoustic Ofdm Decision Quadratic Channel Equalization Method

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Embodiment Construction

[0032] The present invention is described in more detail below in conjunction with accompanying drawing example:

[0033] combine Figure 1~6 , the OFDM system uses comb-shaped pilots to assist channel estimation, uses convolutional coding and Turbo coding as the second equalization decision method, and uses comb-shaped pilot minimum mean square error (CombMMSE) algorithm and block pilot minimum mean square error ( BlockMMSE) algorithm together to complete the decision of the second channel equalization.

[0034] The OFDM system uses comb pilots to assist channel estimation, and the pilot interval is N CF According to the actual channel coherence bandwidth B C Choose to satisfy: in is the subcarrier spacing of OFDM symbols.

[0035] The decision quadratic equalization algorithm adopts convolution coding and Turbo coding as the judgment methods. Convolutional encoding k=1, n=2, constraint length K=4, the block diagram of the encoder is as follows figure 1 As shown, the...

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Abstract

The purpose of the invention is to provide a method for decision of secondary channel equalization of underwater acoustic OFDM. According to the method, a CombMMSE channel estimation is carried out; once equalization is carried out on received data by utilizing a frequency response to obtain post-once equalization data; de-mapping processing is carried out on subcarriers of the post-once equalization data and then estimation of original data is obtained by convolutional decoding or Turbo decoding; coding is again carried out on the decoded data according to an original encoding rule to obtain post-secondary coding data; estimation on block pilot frequency is obtained by taking the estimated data subcarriers as a training sequence and by combining comb pilot frequency subcarriers, so that all subchannels have training data; and then secondary channel estimation is again carried out by utilizing a BlockMMSE algorithm. According to the invention, comb pilot frequency interpolation errors can be substantially reduced; moreover, a good balancing effect can be achieved on the condition that an interval between pilot frequencies is big.

Description

technical field [0001] The invention relates to a decision channel equalization method for high-speed underwater acoustic communication. Background technique [0002] Acoustic waves are the only underwater information carrier that can be transmitted remotely. With the deepening of ocean development, the requirements for transmission efficiency and reliability of underwater mobile communications are getting higher and higher. Since the underwater acoustic channel has the characteristics of narrow bandwidth, strong multipath, high noise, and random time-space-frequency variation, it is an urgent problem to realize high-speed and robust mobile communication between underwater nodes. Orthogonal frequency division multiplexing technology has the advantages of anti-multipath fading, anti-burst interference, etc., and is suitable for high-speed data transmission. However, when applied in an underwater acoustic environment, some subcarriers will experience deep fading due to the mu...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L25/02H04L27/26H04L25/03H04B13/02
Inventor 马雪飞乔钢马璐孙宗鑫周锋刘淞佐郑彩云章佳荣文明王玥
Owner HARBIN ENG UNIV
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