Machine Learning Based Biomimetic Underwater Covert Acoustic Communication Method Using Dolphin Whistle Contours

Abstract

For underwater acoustic covert communications, biomimetic covert communications have been developed using dolphin whistles. The conventional biomimetic covert communication methods transmit slightly different signal patterns from real dolphin whistles, which results in a low degree of mimic (DoM). In this paper, we propose a novel biomimetic communication method that preserves the large DoM with a low bit error rate (BER). For the transmission, the proposed method utilizes the various contours of real dolphin whistles with the link information among consecutive whistles, and the proposed receiver uses machine learning based whistle detectors with the aid of the link information. Computer simulations and practical ocean experiments were executed to demonstrate the better BER performance of the proposed method. Ocean experiments demonstrate that the BER of the proposed method was 0.002, while the BER of the conventional Deep Neural Network (DNN) based detector showed 0.36.

Deep Learning-Based Near-Field Source Localization Without a Priori Knowledge of the Number of Sources

“…To calculate the dependent components, the conventional GS utilizes the inner product, but this paper replaces the inner product with the convolutional layer (Conv) because the Conv attains the features from the inputs [17,18,26,[32][33][34][35][36]. However, since the general Conv sums the convolution results for each channel, this paper utilizes the 1-dimensional…”

The Long-Range Biomimetic Covert Communication Method Mimicking Large Whale

“…Recently, a biomimetic communication method has been studied for military purposes. Biomimetic communication methods make the enemy confuse our communication signals with dolphin or whale sounds to achieve covertness [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Traditional covert communication systems decrease the signal strength and hide the existence of the signal using various techniques (e.g., spread spectrum, chaotic modulation, etc.)…”

“…Low-power spectral density of the transmitted signal causes a low SNR at the receiver, which results in low bit-error-rate (BER) performance. Especially for long-distance communication, low frequency and narrow bandwidth are inevitable, and it is difficult to conceal the signal using these methods [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Biomimetic underwater acoustic communication has been developed to overcome the disadvantage of traditional covert communication.…”

“…Conventional biomimetic communication methods utilize various modulation methods such as chirp spread spectrum (CSS), frequency shift keying (FSK), phase shift keying (PSK), and time-frequency shift keying (TFSK) to modulate bits into whistles [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Conventional biomimetic communication studies have demonstrated their communication performance through ocean experiments.…”

“…In addition, the conventional methods have evaluated the degree of mimic (DoM) by comparing the shape of mimicking the signal with the real whistle. Especially in studies of CV-CFM (based on PSK) and TFSK, the authors performed the mean-of-score (MOS) test and showed that humans could hardly distinguish a mimicking signal from a real dolphin whistle [ 11 , 12 , 13 , 14 ]. All of the conventional studies mimicked the whistle of small dolphins (such as white-sided dolphins utilizing tens of kilohertz sounds) and conducted ocean experiments at a short range within 5 km [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ].…”