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A virtual time-reversal underwater acoustic ofdm channel equalization method

A technology of virtual time reversal and channel equalization, which is applied to shaping networks, baseband system components, and multi-frequency code systems in transmitters/receivers. It can solve problems such as limiting OFDM communication rates and achieve high estimation accuracy, Improve utilization, reduce ISI and the effect of ICI

Active Publication Date: 2017-07-11
HARBIN ENG UNIV
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AI Technical Summary

Problems solved by technology

Existing channel equalization algorithms, such as least square (LS), minimum mean square error (MMSE), etc., need to add a cyclic prefix greater than the maximum multipath delay of the channel to overcome ISI and ICI, and add a denser pilot to estimate the channel , which severely limits the communication rate of OFDM

Method used

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  • A virtual time-reversal underwater acoustic ofdm channel equalization method
  • A virtual time-reversal underwater acoustic ofdm channel equalization method
  • A virtual time-reversal underwater acoustic ofdm channel equalization method

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Embodiment Construction

[0020] Step 1: According to the principle of the virtual time reversal mirror (VTRM), the detection signal for signal estimation is added to the signal transmitted by the transmitter;

[0021] Such as figure 1 As shown, the basic principle of VTRM technology is to send a detection signal before transmitting the information signal, estimate the channel impulse response according to the detection signal, and then convolve the time-reversal signal with the received signal to obtain the virtual time-reversal signal of.

[0022] According to the principle of VTRM, the frame structure of the transmitted signal is designed as figure 2 As shown, the frame header uses a linear frequency modulation (LFM) signal for frame timing synchronization, followed by a single-frequency pulse (CW) signal for estimating the Doppler factor, which is used to eliminate the influence of Doppler frequency offset at the receiving end, and then is the sounding signal, used to estimate the channel impuls...

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Abstract

The invention relates to a virtual time reversal underwater sound OFDM channel equalization method which is characterized by comprising the steps that 1. detecting signals for signal estimation are added into signals sent by a sending end; 2. a receiving end completes a synchronous process, and the received detecting signals are extracted, and according to the received detecting signals, channel impulse response is estimated; 3. according to the estimated channel impulse response, virtual time reversal OFDM channel equalization is completed; and 4. signals after equalization are subjected to serial-parallel conversion, circulating prefixes and circulating postfixes are removed, and a demodulation process is completed.

Description

technical field [0001] The invention relates to a virtual time reversal underwater acoustic OFDM channel equalization method. Background technique [0002] Underwater acoustic channels have the characteristics of limited bandwidth, serious multipath interference, space variation, time variation, and frequency variation. Especially for shallow seawater acoustic channels, affected by the seabed topography and sound velocity distribution, the channels are very complex, and the channel multi-path delay often reaches Hundreds of milliseconds have brought serious interference to underwater acoustic communication. OFDM (Orthogonal Frequency Division Multiplexing) has the advantages of high frequency band utilization, anti-frequency selective fading, and simple equalization, and is widely used in short-range high-speed underwater acoustic communications. Inter-carrier interference (ISI) and inter-carrier interference (ICI), it is necessary to add a cyclic prefix greater than the ma...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L25/03H04L27/26
Inventor 乔钢尹艳玲马璐周峰孙宗鑫刘凇佐马雪飞聂东虎
Owner HARBIN ENG UNIV
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