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Underwater Wireless Communications

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Communications".

Deadline for manuscript submissions: 30 June 2024 | Viewed by 12051

Special Issue Editors

Deportment of Information and Communication Engineering, Xiamen University, 422 Siming South Road, Xiamen 361005, China
Interests: digital communications; wireless communications; modern signal processing; underwater acoustic communication
Special Issues, Collections and Topics in MDPI journals
Electrical Engineering Department, Faculty of Engineering, Aswan University, Aswan 81542, Egypt
Interests: 5G cellular networks; Li-Fi technology; millimeter-wave transmissions; underwater communication

Special Issue Information

Dear Colleagues,

Effective underwater wireless communications (UWCs) are essential for a number of both military and civil applications, such as submarine communication and the discovery of new natural resources. Four communication techniques are utilized in the ocean environment: optical, electromagnetic, magnetic induction communication, and acoustic communication. Each has its advantage and disadvantages. Efforts in this area have been made by both researchers and industry to improve underwater wireless communication and discover the role of ocean water in reinforcing environmental sustainability. However, the physical characteristics of the oceanic environments still pose important challenges. These environmental challenges restrict the recharging capabilities of underwater communication nodes and limit the underwater channel bandwidth. These challenges have motivated us to invite interested researchers to design highly efficient energy and spectral underwater wireless communication systems. The new designs can be based on deep learning and artificial intelligence. This Special Issue may include signal processing algorithms designed to improve underwater wireless sensor nodes, thus enabling the Internet of Underwater Things.

This Special Issue will focus on all types of underwater wireless communication systems, underwater wireless sensor nodes, and the Internet of Underwater Things.   

Prof. Dr. Haixin Sun
Prof. Dr. Hamada Esmaiel
Guest Editors

Manuscript Submission Information

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Published Papers (8 papers)

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Research

20 pages, 1109 KiB  
Article
Improved Frequency Domain Turbo Equalization with Expectation Propagation Interference Cancellation in Underwater Acoustic Communications
by Bin Jiang, Yue Tang, Yinan Zhao, Jianrong Bao, Chao Liu and Xianghong Tang
Sensors 2023, 23(18), 7801; https://0-doi-org.brum.beds.ac.uk/10.3390/s23187801 - 11 Sep 2023
Viewed by 634
Abstract
This paper proposes an improved frequency domain turbo equalization (IFDTE) with iterative channel estimation and feedback to achieve both a good performance and low complexity in underwater acoustic communications (UWACs). A selective zero-attracting (SZA) improved proportionate normal least mean square (SZA-IPNLMS) algorithm is [...] Read more.
This paper proposes an improved frequency domain turbo equalization (IFDTE) with iterative channel estimation and feedback to achieve both a good performance and low complexity in underwater acoustic communications (UWACs). A selective zero-attracting (SZA) improved proportionate normal least mean square (SZA-IPNLMS) algorithm is adopted by utilizing the sparsity of the UWAC channel to estimate it using a training sequence. Simultaneously, a set-membership (SM) SZA differential IPNLMS (SM SZA-DIPNLMS) with variable step size is adopted to estimate the channel status information (CSI) in the iterative channel estimation with soft feedback. In this way, the computational complexity for iterative channel estimation is reduced effectively with minimal performance loss. Different from traditional schemes in UWACs, an IFDTE with expectation propagation (EP) interference cancellation is adopted to estimate the a posteriori probability of transmitted symbols iteratively. A bidirectional IFDTE with the EP interference cancellation is proposed to further accelerate the convergence. THe simulation results show that the proposed channel estimation obtains 1.9 and 0.5 dB performance gains, when compared with those of the IPNLMS and the l0-IPNLMS at a bit error rate (BER) of 103. The proposed channel estimation also effectively reduces the unnecessary updating of the coefficients of the UWAC channel. Compared with traditional time-domain turbo equalization and FDTE in UWACs, the IFDTE obtains 0.5 and 1 dB gains in the environment of SPACE’08 and it obtains 0.5 and 0.4 dB gains in the environment of MACE’04 at a BER of 103. Therefore, the proposed scheme obtains a good BER performance and low complexity and it is suitable for efficient use in UWACs. Full article
(This article belongs to the Special Issue Underwater Wireless Communications)
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17 pages, 5562 KiB  
Article
Modulation Recognition Method for Underwater Acoustic Communication Signals Based on Passive Time Reversal-Autoencoder with the Synchronous Signals
by Yalin Hu, Jixin Bao, Wanzhong Sun and Xiaomei Fu
Sensors 2023, 23(13), 5997; https://0-doi-org.brum.beds.ac.uk/10.3390/s23135997 - 28 Jun 2023
Viewed by 887
Abstract
In the process of the modulation recognition of underwater acoustic communication signals, the multipath effect seriously interferes with the signal characteristics, reducing modulation recognition accuracy. The existing methods passively improve the accuracy from the perspective of selecting appropriate signal features, lacking specialized preprocessing [...] Read more.
In the process of the modulation recognition of underwater acoustic communication signals, the multipath effect seriously interferes with the signal characteristics, reducing modulation recognition accuracy. The existing methods passively improve the accuracy from the perspective of selecting appropriate signal features, lacking specialized preprocessing for suppressing multipath effects. So, the accuracy improvement of the designed modulation recognition models is limited, and the adaptability to environmental changes is poor. The method proposed in this paper actively utilizes common synchronous signals in underwater acoustic communication as detection signals to achieve passive time reversal without external signals and designs a passive time reversal-autoencoder to suppress multipath effects, enhance signals’ features, and improve modulation recognition accuracy and environmental adaptability. Firstly, synchronous signals are identified and estimated. Subsequently, a passive time reversal-autoencoder is designed to enhance power spectrum and square spectrum features. Finally, a modulation classification is performed using a convolutional neural network. The model is trained in simulation channels generated by Bellhop and tested in actual channels which are different from the training period. The average recognition accuracy of the six modulated signals is improved by 10% compared to existing passive modulation recognition methods, indicating good environmental adaptability as well. Full article
(This article belongs to the Special Issue Underwater Wireless Communications)
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13 pages, 5920 KiB  
Article
Vector Sensor Steering-Dependent Performance in an Underwater Acoustic Communication Field Experiment
by Fabricio A. Bozzi and Sérgio M. Jesus
Sensors 2022, 22(21), 8332; https://0-doi-org.brum.beds.ac.uk/10.3390/s22218332 - 30 Oct 2022
Cited by 1 | Viewed by 1327
Abstract
This paper shows the performance resulting from combining vector sensor directional components in an underwater acoustic communication experiment. The objective is to relate performance with transmission direction and range. Receiver structures based on beamforming and passive time-reversal are tested in order to quantify [...] Read more.
This paper shows the performance resulting from combining vector sensor directional components in an underwater acoustic communication experiment. The objective is to relate performance with transmission direction and range. Receiver structures based on beamforming and passive time-reversal are tested in order to quantify and compare the steerability impact of vector sensor directional components. A shallow water experiment is carried out with a bottom fixed two-axis pressure-gradient vector sensor. A ship suspended acoustic source transmits coherent modulated communication signals at various ranges and from several directions. Results show that one vector sensor can provide an up to 10 times smaller error bit rate than a pressure sensor, favoring communication robustness without size penalty. Full article
(This article belongs to the Special Issue Underwater Wireless Communications)
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15 pages, 6115 KiB  
Article
Communication System Based on Magnetic Coils for Underwater Vehicles
by Giovanni Canales-Gómez, Gloria León-Gónzalez, Neguib Jorge-Muñoz, José Humberto Arroyo-Núñez, Elba Dolores Antonio-Yañez and Rafael Stanley Núñez-Cruz
Sensors 2022, 22(21), 8183; https://0-doi-org.brum.beds.ac.uk/10.3390/s22218183 - 26 Oct 2022
Cited by 4 | Viewed by 1528
Abstract
In this work, a wireless communication system based on magnetic coils for underwater vehicles is presented. Firstly, the mathematical model of magnetic field induction using magnetic coils is discussed. Then, a description of the proposed communication system is presented, including the main components [...] Read more.
In this work, a wireless communication system based on magnetic coils for underwater vehicles is presented. Firstly, the mathematical model of magnetic field induction using magnetic coils is discussed. Then, a description of the proposed communication system is presented, including the main components of the transmitter and receiver module. The experimental results show that due to the properties of the magnetic field, the proposed communication system can work properly in different environments such as air or water with the same efficiency. Underwater tests were carried out in different water circumstances: varying the temperature in a range from 10 °C to 35 °C, varying concentrations of clay in a range from 0% to 10%, and varying the salinity concentration in a range from 1000 ppm ( parts per million) to 35,000 ppm. It was observed that these conditions do not affect the information transfer. Finally, the advantages of using the proposed system compared to existing submarine communication systems are discussed. Full article
(This article belongs to the Special Issue Underwater Wireless Communications)
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16 pages, 4306 KiB  
Article
The Long-Range Biomimetic Covert Communication Method Mimicking Large Whale
by Jongmin Ahn, Deawon Do and Wanjin Kim
Sensors 2022, 22(20), 8011; https://0-doi-org.brum.beds.ac.uk/10.3390/s22208011 - 20 Oct 2022
Cited by 1 | Viewed by 1187
Abstract
Short-range biomimetic covert communications have been developed using dolphin whistles for underwater acoustic covert communications. Due to a channel characteristics difference by range, the conventional short-range methods cannot be directly applied to long-range communications. To enable long-range biomimicking communication, overcoming the large multipath [...] Read more.
Short-range biomimetic covert communications have been developed using dolphin whistles for underwater acoustic covert communications. Due to a channel characteristics difference by range, the conventional short-range methods cannot be directly applied to long-range communications. To enable long-range biomimicking communication, overcoming the large multipath delay and a high degree of mimic (DoM) in the low-frequency band is required. This paper proposes a novel biomimetic communication method that preserves a low bit-error rate (BER) with a large DoM in the low-frequency band. For the transmission, the proposed method utilizes the time-dependent frequency change of the whistle, and its receiver obtains additional SNR gain from the multipath delay. Computer simulations and practical ocean experiments were executed to demonstrate that the BER performance of the proposed method is better than the conventional methods. For the DoM assessment, the novel machine learning-based method was utilized, and the result shows that the whistles generated by the proposed method were recognized as the actual whistle of the right humpback whale. Full article
(This article belongs to the Special Issue Underwater Wireless Communications)
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22 pages, 7669 KiB  
Article
Energy Harvesting for TDS-OFDM in NOMA-Based Underwater Communication Systems
by Hamada Esmaiel and Haixin Sun
Sensors 2022, 22(15), 5751; https://0-doi-org.brum.beds.ac.uk/10.3390/s22155751 - 01 Aug 2022
Cited by 2 | Viewed by 1372
Abstract
Non-orthogonal multiple access (NOMA) is considered a promising multiple access technique for fifth generation (5G) mobile networks and tactical internet due to its high spectral efficiency. Thanks to the high spectral efficiency of NOMA, it can be a strong candidate suitable for the [...] Read more.
Non-orthogonal multiple access (NOMA) is considered a promising multiple access technique for fifth generation (5G) mobile networks and tactical internet due to its high spectral efficiency. Thanks to the high spectral efficiency of NOMA, it can be a strong candidate suitable for the limited channel bandwidth of underwater acoustic communication. The NOMA transmitter is employing superposition coding (SC). The NOMA receiver is based on the successive interference cancellation (SIC) technique. The multicarrier NOMA adopts orthogonal frequency division multiplexing (OFDM) as a multicarrier modulation (MCM) technique; however, conventional cyclic prefix OFDM (CP-OFDM) and zero padding (ZP-OFDM) have inefficient spectral efficiency. Thanks to efficient synchronization and high energy-spectral efficiency of the time-division synchronization OFDM (TDS-OFDM), it is a significant attractive candidate for underwater multicarrier communication. However, wasting the power transmission of long guard intervals in the battery-based underwater communication is represented as one of the TDS-OFDM main drawbacks. Harvesting energy and improving the energy efficiency of acoustic-based TDS-OFDM-NOMA represent high achievement goal battery recharging challenges due to the ocean environment. This paper proposes time switching simultaneous wireless information and power transfer (TS-SWIPT) to harvest the energy of transmitted power over the guard interval in the TDS-OFDM-NOMA scheme. The proposed energy harvested scheme harvests the energy from the wasted power in the long guard interval and improves the energy efficiency of the TDS-OFDM multicarrier scheme. This study demonstrates the superiority of the proposed TDS-OFDM-NOMA over the underwater acoustic channel by revealing high energy efficiency, high spectral efficiency, better bit error rate performance, and high system data throughput. Full article
(This article belongs to the Special Issue Underwater Wireless Communications)
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13 pages, 4806 KiB  
Article
Prefiltered Single-Carrier Frequency-Domain Equalization for Binary CPM over Shallow Water Acoustic Channel
by Ruigang Han, Ning Jia, Zhongyuan Guo, Jianchun Huang, Dong Xiao and Shengming Guo
Sensors 2022, 22(10), 3821; https://0-doi-org.brum.beds.ac.uk/10.3390/s22103821 - 18 May 2022
Cited by 1 | Viewed by 1288
Abstract
The continuous phase modulation (CPM) technique is an excellent solution for underwater acoustic (UWA) channels with limited bandwidth and high propagation attenuation. However, the severe intersymbol interference is a big problem for the algorithm applying in shallow water. To solve this problem, an [...] Read more.
The continuous phase modulation (CPM) technique is an excellent solution for underwater acoustic (UWA) channels with limited bandwidth and high propagation attenuation. However, the severe intersymbol interference is a big problem for the algorithm applying in shallow water. To solve this problem, an algorithm for prefiltered single-carrier frequency-domain equalization (PF-SCFDE) is presented in this paper. The regular whitening filter is replaced by a prefilter in the proposed algorithm. The output information sequence of this prefilter contains the forward information. To improve the performance, the output of the equalizer, combined with the forward information, is used to make the maximum likelihood estimation. The simulation results with minimum-shift keying and Gaussian-filtered minimum-shift keying signals over shallow water acoustic channels with low root mean square delay spread demonstrate that PF-SCFDE outperformed the traditional single-carrier frequency-domain equalization (SCFDE) by approximately 1 dB under a bit error rate (BER) of 10−4. A shallow sea trial has demonstrated the effectiveness of PF-SCFDE; PF-SCFDE had a reduction in BER of 18.35% as compared to the traditional SCFDE. Full article
(This article belongs to the Special Issue Underwater Wireless Communications)
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15 pages, 4906 KiB  
Article
A Method for Underwater Wireless Data Transmission in a Hydroacoustic Channel under NLOS Conditions
by Jerzy Mizeraczyk, Ryszard Studanski, Andrzej Zak and Agnieszka Czapiewska
Sensors 2021, 21(23), 7825; https://0-doi-org.brum.beds.ac.uk/10.3390/s21237825 - 24 Nov 2021
Cited by 6 | Viewed by 2195
Abstract
Wireless data transmission in the hydroacoustic channel under non-line-of-sight (NLOS) propagation conditions, for example, during a wreck penetration, is difficult to implement reliably. This is mostly due to the multipath propagation, which causes a reduction in the quality of data reception. Therefore, in [...] Read more.
Wireless data transmission in the hydroacoustic channel under non-line-of-sight (NLOS) propagation conditions, for example, during a wreck penetration, is difficult to implement reliably. This is mostly due to the multipath propagation, which causes a reduction in the quality of data reception. Therefore, in this work an attempt has been made to develop a reliable method of wireless underwater communication test it under the NLOS conditions. In our method, we used multiple frequency-shift keying (MFSK) modulation, sending a single bit on two carriers, and diversity combining. The method was tested in laboratory conditions which simulated underwater signal propagation during the penetration of the wreck. The propagation conditions were investigated by determining the impulse responses at selected measurement points using the correlation method. Additionally, for comparison, the data transmission quality was determined by the bit error rate (BER) under the same conditions using direct sequence spread spectrum (DSSS) and binary phase shift keying (BPSK) modulation. The obtained results confirmed the usefulness of the application of the developed method for wireless data transmission in a hydroacoustic channel under NLOS conditions. Full article
(This article belongs to the Special Issue Underwater Wireless Communications)
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