An Underwater Time Reversal Communication Method Using Symbol-Based Doppler Compensation with a Single Sound Pressure Sensor

Due to the significant multipath and Doppler effects in the underwater acoustic (UWA) channel, the quality of the received signal is degraded, which seriously affects the performance of UWA communication. The paper proposes a time reversal UWA communication method combined with a symbol-based Doppler compensation (SBDC) technique to solve those problems. A single element time reversal mirror (TRM) is used to realize channel equalization and mitigate the inter-symbol interference (ISI) resulting from multipath propagation. The SBDC technique is subsequently used to compensate Doppler effects in the received signal, thereby reducing the bit error rate (BER) and improving the communication performance. In order to verify the performance of the proposed communication method, some simulations with real sounding channels were performed. Moreover, a field UWA communication experiment was conducted in the Songhua River (Harbin, China). The UWA communication experiment achieves nearly error-free performance with a communication rate of 100 bit/s in the bandwidth of 2 kHz. The results of the experiment demonstrate the feasibility and robustness of the proposed UWA communication method.

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Multiuser underwater acoustic communication using single-element virtual time reversal mirror

Science Bulletin ◽

10.1007/s11434-009-0155-x ◽

2009 ◽

Vol 54 (8) ◽

pp. 1302-1310 ◽

Cited By ~ 7

Author(s):

JingWei Yin ◽

YiLin Wang ◽

Lei Wang ◽

JunYing Hui

Keyword(s):

Acoustic Communication ◽

Time Reversal ◽

Underwater Acoustic Communication ◽

Single Element ◽

Underwater Acoustic ◽

Virtual Time ◽

Time Reversal Mirror

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Target Echo Enhancement Using a Single-Element Time Reversal Mirror

IEEE Journal of Oceanic Engineering ◽

10.1109/joe.2005.862131 ◽

2005 ◽

Vol 30 (4) ◽

pp. 912-920 ◽

Cited By ~ 9

Author(s):

L. Pautet ◽

A. Tesei ◽

P. Guerrini ◽

E. Pouliquen

Keyword(s):

Time Reversal ◽

Single Element ◽

Time Reversal Mirror

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Study on Time Reversal Maximum Ratio Combining in Underwater Acoustic Communications

Applied Sciences ◽

10.3390/app11041509 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1509

Author(s):

Anbang Zhao ◽

Caigao Zeng ◽

Juan Hui ◽

Keren Wang ◽

Kaiyu Tang

Keyword(s):

Time Reversal ◽

Signal To Noise Ratio ◽

Spatial Diversity ◽

Single Element ◽

Noise Power ◽

Theoretical Derivation ◽

Underwater Acoustic ◽

Maximum Ratio Combining ◽

Weight Coefficients ◽

Output Snr

Time reversal (TR) can achieve temporal and spatial focusing by exploiting spatial diversity in complex underwater environments with significant multipath. This property makes TR useful for underwater acoustic (UWA) communications. Conventional TR is realized by performing equal gain combining (EGC) on the single element TR output signals of each element of the vertical receive array (VRA). However, in the actual environment, the signal-to-noise ratio (SNR) and the received noise power of each element are different, which leads to the reduction of the focusing gain. This paper proposes a time reversal maximum ratio combining (TR-MRC) method to process the received signals of the VRA, so that a higher output SNR can be obtained. The theoretical derivation of the TR-MRC weight coefficients indicates that the weight coefficients are only related to the input noise power of each element, and are not affected by the multipath structure. The correctness of the derivation is demonstrated with the experimental data of the long-range UWA communications conducted in the South China Sea. In addition, the experimental results illustrate that compared to the conventional TR, TR-MRC can provide better performance in terms of output SNR and bit error rate (BER) in UWA communications.

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M-ary nonlinear sine chirp spread spectrum for underwater acoustic communication based on virtual time-reversal mirror method

EURASIP Journal on Wireless Communications and Networking ◽

10.1186/s13638-021-01995-3 ◽

2021 ◽

Vol 2021 (1) ◽

Author(s):

Songzuo Liu ◽

Habib Hussain Zuberi ◽

Yi Lou ◽

Muhmmad Bilal Farooq ◽

Shahabuddin Shaikh ◽

...

Keyword(s):

Acoustic Communication ◽

Time Reversal ◽

Spread Spectrum ◽

Underwater Acoustic Communication ◽

Half Cycle ◽

Spreading Factor ◽

Underwater Acoustic ◽

Virtual Time ◽

Chirp Spread Spectrum ◽

Time Reversal Mirror

AbstractLinear chirp spread spectrum technique is widely used in underwater acoustic communication because of their resilience to high multipath and Doppler shift. Linear frequency modulated signal requires a high spreading factor to nearly reach orthogonality between two pairs of signals. On the other hand, nonlinear chirp spread spectrum signals can provide orthogonality at a low spreading factor. As a result, it improves spectral efficiency and is more insensitive to Doppler spread than the linear counterpart. To achieve a higher data rate, we propose two variants (half cycle sine and full cycle sine) of the M-ary nonlinear sine chirp spread spectrum technique based on virtual time-reversal mirror (VTRM). The proposed scheme uses different frequency bands to transmit chirp, and VTRM is used to improve the bit error rate due to high multipath. Its superior Doppler sensitivity makes it suitable for underwater acoustic communication. Furthermore, the proposed method uses a simple, low-power bank of matched filters; thus, it reduces the overall system complexity. Simulations are performed in different underwater acoustic channels to verify the robustness of the proposed scheme.

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