A method based on time-frequency masking for MFSK underwater acoustic communication signal enhancement

2016 ◽  
Author(s):  
Yang Yu ◽  
Peng Han ◽  
Xiaomin Zhang
Keyword(s):  
Acoustic Communication ◽  
Signal Enhancement ◽  
Underwater Acoustic Communication ◽  
Underwater Acoustic ◽  
Time Frequency ◽  
Communication Signal

scholarly journals Bionic Morse Coding Mimicking Humpback Whale Song for Covert Underwater Communication

2019 ◽  
Vol 10 (1) ◽  
pp. 186 ◽  
Author(s):  
Bilal ◽  
Liu ◽  
Qiao ◽  
Wan ◽  
Tao
Keyword(s):  
Acoustic Communication ◽  
English Language ◽  
Matching Pursuit ◽  
Signal To Noise Ratio ◽  
Humpback Whale ◽  
Humpback Whales ◽  
Underwater Acoustic Communication ◽  
Underwater Acoustic ◽  
Transmission Distance ◽  
Communication Signal

A novel method of bionic Morse coding mimicking humpback whale vocal is presented for covert underwater acoustic communication. The complex humpback whale song is translated as bionic Morse codes based on information entropy. The communication signal is made akin to the natural singing of male humpback whales. The intruder can detect the signal but will not be able to recognize the communication signal due to unified resemblance with the natural sound. This novel technique gives an excellent low probability of recognition characteristics. A flawless stealthy underwater acoustic communication has been established which has negligible chances of deciphered with high imperceptibility. Standard mimicry Morse codes have been developed for the characters of the English language and compared with Morse coding. Covert information of one character per second can be watermarked with perfect stealth and clandestine communication. This novel concept has been verified at transmission distance of five km and less than 10−3 Bit Error Rate (BER) is achieved at Signal to Noise Ratio (SNR) down to negative seven dB. Zero BER is attained by estimating the channel by a matching pursuit algorithm and equalizing the errors by virtual time reversal mirror technique.

scholarly journals Symmetry Oriented Covert Acoustic Communication by Mimicking Humpback Whale Song

Symmetry ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 752 ◽  
Author(s):  
Gang Qiao ◽  
Muhammad Bilal ◽  
Songzuo Liu ◽  
Tianlong Ma ◽  
Yunjiang Zhao ◽  
...  
Keyword(s):  
Acoustic Communication ◽  
Matching Pursuit ◽  
Signal To Noise Ratio ◽  
Humpback Whale ◽  
Underwater Acoustic Communication ◽  
Covert Communication ◽  
Underwater Acoustic ◽  
Communication Signal ◽  
Tank Experiment ◽  
Novel Concept

To meet the increasing demand of covert underwater acoustic communication, biologically inspired mimicry communication watermarking the data in symmetrical humpback whale song is presented. Mimicry is an entirely different approach from traditional covert communication where data are transmitted by spreading the waveform at a low signal to noise ratio. In this innovative technique, the carrier signal is imitated symmetrical to the ocean background noise, which can be shipping noise, anthropological noise, or the vocals emitted by sea animals. The eavesdropper can detect the communication signal, but will assume it to be real ocean noise due to its symmetry. It excludes the mimicked signal from recognition, which makes the communication covert. In this research, we watermarked the covert information in humpback whale song using discrete cosine transform in the frequency domain. The mimicked symmetrical signal provided excellent imperceptibility with the real song and an outstanding camouflage effect was calculated. We validated the novel concept by simulation and underwater tank experiment. 10−4 BER was achieved in the underwater tank experiment, which was diminished to zero error by using matching pursuit estimation and virtual time reversal equalization. This novel bionic covert communication technique is feasible for clandestine underwater acoustic communication in the presence of an eavesdropper with better imperceptibility.

scholarly journals A low-complexity orthogonal time frequency space modulation method for underwater acoustic communication

2021 ◽  
Vol 39 (5) ◽  
pp. 954-961
Author(s):  
Yang ZHANG ◽  
Qunfei ZHANG ◽  
Yingjie WANG ◽  
Chengbing HE ◽  
Wentao SHI
Keyword(s):  
Acoustic Communication ◽  
Low Complexity ◽  
Modulation Method ◽  
Underwater Acoustic Communication ◽  
Underwater Acoustic ◽  
Frequency Space ◽  
Time Frequency ◽  
Symbol Detection ◽  
Equalization Algorithm ◽  
Infinite Norm

Compared with the orthogonal frequency division multiplexing (OFDM) modulation, the orthogonal time frequency space(OTFS) modulation has a lower peak-to-average power ratio. It can effectively resist the time selective fading caused by the Doppler effect and has significant performance advantages over doubly dispersive channels. However, the conventional OTFS linear minimum mean square error (LMMSE) method has a high complexity and is not easy to process in real time. In order to solve this problem, we propose a low-complexity equalization algorithm with infinite norm constraints based on the optimal coordinate reduction. The equalization algorithm not only obtains the optimal solution through a certain number of iterations and avoids direct matrix inversion but also equalizes infinite norm constraints to improve the symbol detection performance gains. At the same time, the OTFS delay-Doppler channel matrix we utilize is sparse and the two-norm squares of each column vector equally reduces the complexity of optimal coordinate descent. Finally, the simulation in the underwater acoustic communication scenario we designed verify the effectiveness of the proposed equalization algorithm. The simulation results show that the performance of the proposed equalization algorithm is close to that of the LMMSE method, while its low complexity is ensured.

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