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1
Lee. "Underwater Acoustic Communication Using Nonlinear Chirp Signal". Journal Of The Acoustical Society Of Korea 33, n.º 4 (2014): 255. http://dx.doi.org/10.7776/ask.2014.33.4.255.
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Hovem, Jens M. y Hefeng Dong. "Understanding Ocean Acoustics by Eigenray Analysis". Journal of Marine Science and Engineering 7, n.º 4 (25 de abril de 2019): 118. http://dx.doi.org/10.3390/jmse7040118.
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Acoustics is important for all underwater systems for object detection, classification, surveillance systems, and communication. However, underwater acoustics is often difficult to understand, and even the most carefully conducted measurements may often give unexpected results. The use of theory and acoustic modelling in support of measurements is very important since theory tends to be better behaved and more consistent than experiments, and useful to acquire better knowledge about the physics principle. This paper, having a tutorial flair, concerns the use of ray modelling and in particular eigenray analysis to obtain increased knowledge and understanding of underwater acoustic propagation.
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Allam, Ahmed, Waleed Akbar y Fadel Adib. "An analytical framework for low-power underwater backscatter communications". Journal of the Acoustical Society of America 153, n.º 3_supplement (1 de marzo de 2023): A376. http://dx.doi.org/10.1121/10.0019235.
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Acoustic underwater backscatter enables ultra-low-power communication with applications in ocean exploration, monitoring, navigation, and aquaculture. Unlike traditional communication systems, acoustic backscatter does not require active signal generation. Instead, it communicates data by modulating existing acoustic signals, requiring few microwatts of power for operation. Backscatter communication enables ultra-low power sensors by switching between absorbing and reflecting acoustic waves transmitted from a central station. The energy burden is shifted to the transmitting station, and the acoustic power supplied by the station can power the sensor, allowing for battery-free operation. Initial demonstrations of underwater backscatter communication were encouraging; however, the theoretical and practical limits are still unknown. In this work, we develop a multiphysics analytical framework for the communication and power link budget of underwater backscatter. The framework calculates practical communication and power-up range, transmitter power budget, and signal-to-noise ratio, accounting for transducers’ characteristics and the underwater communication channel. The analytical predictions are validated for practical transducers using high-fidelity piezo-acoustic finite element simulations and experimental measurements. The framework will guide future backscatter systems design, identifying practical operation ranges and optimal frequencies for data transmission and batteryless operation.
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Majeed, Ishrat y Er Jasdeep Singh. "Design and Performance Analysis of Underwater Acoustic Sensor Networks". International Journal for Research in Applied Science and Engineering Technology 10, n.º 3 (31 de marzo de 2022): 294–303. http://dx.doi.org/10.22214/ijraset.2022.40599.
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Abstract: The underwater acoustic sensor network (UASN) is essential for exploration missions and observation in demanding environments. The UASN'S connection route is acoustic waves, which limits its usefulness in comparison to ground sensor networks. This is the case because to its limited capacity, latency, and significant route loss. This article provides comprehensive research of the characteristics of UASN. We explore the functionality of underwater acoustic ad-hoc networks in the presence of disruptions. RF signals are used as a communication mechanism in wireless sensor networks, both terrestrial and aerial. However, in a sub-sea setting, such as deep-sea research, detecting and transmitting data needs a completely different method to underwater communication. The fact that the seas cover 70% of the earth's surface and contain massive amounts of unexplored riches cannot be ignored. The aquatic environment has largely escaped the effects of recent breakthroughs in wireless sensor networks (WSNS) and their broad application in latest studies and economic progress. Research on underwater acoustic sensor networks (UASNS) is developing at a snail's pace due to the difficulties in transferring most of the state-of-the-art of land and air based WSNS to its aquatic equivalent. The bulk of underwater activities rely on acoustic communication and specialized sensors that can endure the harsh environment of the oceans. The purpose of this study is to investigate how UASN works in different situations. End-to-end latency and energy consumption are examined in response to a variety of factors. We also investigate how well underwater acoustic ad-hoc networks perform when nodes are dispersed, and the network is large. Keywords: Under water Acoustics, Sensor, Wireless Sensor Networks, Energy Consumptions.
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Jeon, Jun-Ho y Sung-Joon Park. "Micro-Modem for Short-Range Underwater Mobile Communication Systems". Marine Technology Society Journal 50, n.º 2 (1 de marzo de 2016): 48–53. http://dx.doi.org/10.4031/mtsj.50.2.4.
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AbstractRecently, there has been great interest in short-range underwater communication for applications such as water pollution monitoring, fish farming, oceanographic data collection, and underwater tactical surveillance based on underwater sensor network systems. Because underwater wireless communication relies primarily on acoustics, the development of acoustic modems has been an important topic that needs to be addressed. Furthermore, for years, underwater biomimetic fish robots have been studied in the area of biomechanics for scientific use and reconnaissance missions. In this article, we describe an underwater mobile communication system where fish robots act as sensor nodes, which is different from the conventional concept of an underwater sensor network that is static. We describe the issues that need to be resolved to provide mobility to a node, and we develop a micro-modem to meet the requirements of a moving node. Experiments conducted with prototypes in both a lake and a river verify that the proposed system provides a new degree of freedom (mobility) and is a viable approach.
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Zhou, Yuehai, Feng Tong y Xiaoyu Yang. "Research on Co-Channel Interference Cancellation for Underwater Acoustic MIMO Communications". Remote Sensing 14, n.º 19 (10 de octubre de 2022): 5049. http://dx.doi.org/10.3390/rs14195049.
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Multiple-input–multiple-output (MIMO) communication systems utilize multiple transmitters to send different pieces of information in parallel. This offers a promising way to communicate at a high data rate over bandwidth-limited underwater acoustic channels. However, underwater acoustic MIMO communication not only suffers from serious inter-symbol interference, but also critical co-channel interference (CoI), both of which degrade the communication performance. In this paper, we propose a new framework for underwater acoustic MIMO communications. The proposed framework consists of a CoI-cancellation-based channel estimation method and channel-estimation-based decision feedback equalizer (CE-DFE) with CoI cancellation functionalities for underwater acoustic MIMO communication. We introduce a new channel estimation model that projects the received signal to a specific subspace where the interference is free; therefore, the CoI is cancelled. We also introduce a CE-DFE with CoI cancellation by appending some filters from traditional CE-DFE. In addition, the traditional direct adaptive decision feedback equalization (DA-DFE) method and the proposed method are compared in terms of communication performance and computational complexity. Finally, the sea trial experiment demonstrates the effectiveness and merits of the proposed method. The proposed method achieves a more than 1 dB of output SNR over traditional DA-DFE, and is less sensitive to parameters. The proposed method provides a new approach to the design of robust underwater acoustic MODEM.
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Xu, Jie, Hui Li, You-Ling zhou, Qian Li, Liu-Xun Xue, Chong-Yue Shi y Hou Wang. "Performance analysis of vortex acoustic wave based on uniform circular array". Journal of Physics: Conference Series 2078, n.º 1 (1 de noviembre de 2021): 012069. http://dx.doi.org/10.1088/1742-6596/2078/1/012069.
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Abstract As a carrier for information and energy, acoustic waves have been applied in underwater communication widely, however, the narrow band and low transmission speed are the main problems. Whether in the field of optics or electromagnetic waves, the orbital angular momentum (OAM) represents the natural properties of the spiral phase structure. By introducing the OAM into the acoustics field, the transmission capacity and spectrum efficiency of the underwater acoustic communication system can be expanded. Based on the analysis and detection of the vortex acoustic wave generated by the circular array of transducers, we studied the array generation method of the spiral acoustic beam, and gave the characteristics of the vortex acoustic beam when propagating under the water. In the direction of the main axis, the uniform circular array was used to generate different topological acoustic vortex. To determine the relationship between the OAM topology mode and the transducer array, the spiral acoustic waves in different topology modes were generated, and the number of array elements, array radius, transmission frequency, etc. were investigated to give the effects on OAM acoustic vortex.
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Lee. "Underwater Acoustic Communication of FH-MFSK Method with Multiple Orthogonal Properties". Journal of the Acoustical Society of Korea 33, n.º 6 (2014): 407. http://dx.doi.org/10.7776/ask.2014.33.6.407.
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Yun, Changho. "Underwater Multi-Channel MAC with Cognitive Acoustics for Distributed Underwater Acoustic Networks". Sensors 24, n.º 10 (10 de mayo de 2024): 3027. http://dx.doi.org/10.3390/s24103027.
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The advancement of underwater cognitive acoustic network (UCAN) technology aims to improve spectral efficiency and ensure coexistence with the underwater ecosystem. As the demand for short-term underwater applications operated under distributed topologies, like autonomous underwater vehicle cluster operations, continues to grow, this paper presents Underwater Multi-channel Medium Access Control with Cognitive Acoustics (UMMAC-CA) as a suitable channel access protocol for distributed UCANs. UMMAC-CA operates on a per-frame basis, similar to the Multi-channel Medium Access Control with Cognitive Radios (MMAC-CR) designed for distributed cognitive radio networks, but with notable differences. It employs a pre-determined data transmission matrix to allow all nodes to access the channel without contention, thus reducing the channel access overhead. In addition, to mitigate the communication failures caused by randomly occurring interferers, UMMAC-CA allocates at least 50% of frame time for interferer sensing. This is possible because of the fixed data transmission scheduling, which allows other nodes to sense for interferers simultaneously while a specific node is transmitting data. Simulation results demonstrate that UMMAC-CA outperforms MMAC-CR across various metrics, including those of the sensing time rate, controlling time rate, and throughput. In addition, except for in the case where the data transmission time coefficient equals 1, the message overhead performance of UMMAC-CA is also superior to that of MMAC-CR. These results underscore the suitability of UMMAC-CA for use in challenging underwater applications requiring multi-channel cognitive communication within a distributed network architecture.
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Yoon, Jong Rak. "Performance of Convolution Coding Underwater Acoustic Communication System on Frequency Selectivity Index". JOURNAL OF THE ACOUSTICAL SOCIETY OF KOREA 32, n.º 6 (2013): 494. http://dx.doi.org/10.7776/ask.2013.32.6.494.
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Kim, J. S. "Mitigation of Inter-Symbol Interference in Underwater Acoustic Communication Using Spatial Filter". Journal Of The Acoustical Society Of Korea 33, n.º 1 (2014): 48. http://dx.doi.org/10.7776/ask.2014.33.1.048.
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N, Reshma y T. K. Ramesh. "Underwater channel design for diver communication". International Journal of Engineering & Technology 7, n.º 1.8 (28 de febrero de 2018): 214. http://dx.doi.org/10.14419/ijet.v7i1.9352.
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Underwater channels are usually considered to be very difficult media for communication purposes. There are many reasons that pull back us from considering these types of channels for communication purposes. Limited bandwidth, Doppler effect, multipath propagation etc are some of those reasons. These reasons limit the usage of underwater channel for wide range of applications.Optical waves, RF waves and acoustic waves are generally used. Among the methods, acoustic waves are used in most of the cases since less attenuation and scattering properties are offered by acoustic waves. There are many acoustic channel models existing but require some improvisations according to the diving application. An efficient acoustic underwater channel for diver communication is designed and implemented in this paper. Rayleigh channel model is considered in our algorithm that can deal with multipath propagation and Doppler effect with underwater specifications incorporated to it.This method gives a better result compared to OFDM and MIMO models. Further, a comparison between different modulation techniques like ASK, BPSK and QAM have been done. Results show QAM is a better modulation scheme for underwater environment.
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Campo-Valera, María y Ivan Felis. "Underwater Acoustic Communication for The Marine Environment’s Monitoring". Proceedings 42, n.º 1 (14 de noviembre de 2019): 51. http://dx.doi.org/10.3390/ecsa-6-06642.
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Within the possibilities of non-linear acoustics, the parametric effect offers a range of acoustic applications that are currently being exploited in different areas. In underwater acoustics, environmental monitoring and security are one of the applications that can benefit from these technologies, allowing the transmission of information in a directivity controlled and efficient manner. An essential aspect for the optimal functioning of these technologies is the choice of the modulation that best suits the needs of communication. In the present work, different modulation techniques are explained, through their non-linear propagation, that allows generating the signals to be propagated. Among the modulations presented in this work, we have Amplitude Modulation (AM), Continuous Phase Frequency Shift Keying (CPFSK), and Linear Frequency Modulation (LFM) modulations normally used in communications. These modulations are performed with a modulating signal (sine and sine-sweeps type) whose non-linear demodulation determines the shape of the 1 and 0 bits, through the transmission of a bit string. With all this, comparisons are made between each technique, to obtain a more precise detection and discrimination of the bits.
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Zhou, Lin, Lan Jun Liu y Shu Kai Chi. "Reliability Analysis of Turbo Code for High-Speed Underwater Acoustic Communication Based on OFDM". Applied Mechanics and Materials 475-476 (diciembre de 2013): 832–37. http://dx.doi.org/10.4028/www.scientific.net/amm.475-476.832.
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With the rapid development of OFDM (Orthogonal Frequency Division Multiplexing) technology and its own advantages, this technology has been studied actively in underwater acoustic communication recently to improve the data transfer rate and reliability. This paper introduces the key technology of high speed OFDM underwater acoustic communication, analyzes the advantages and disadvantages, design a high-speed underwater acoustic OFDM communication coding scheme based on TURBO code, and proceeding the simulation and analysis for the OFDM system. Finally, the reliability of TURBO code in high speed underwater acoustic OFDM communication is analyzed.
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Lončar, Ivan, Anja Babić, Barbara Arbanas, Goran Vasiljević, Tamara Petrović, Stjepan Bogdan y Nikola Mišković. "A Heterogeneous Robotic Swarm for Long-Term Monitoring of Marine Environments". Applied Sciences 9, n.º 7 (2 de abril de 2019): 1388. http://dx.doi.org/10.3390/app9071388.
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This paper describes an underwater acoustic sensor network consisting of a heterogeneous robotic swarm used for long-term monitoring of underwater environments. The swarm consists of a large number of underwater robots acting as sensor nodes with limited movement capabilities, and a few surface robots aiding them in accomplishing underwater monitoring scenarios. Main interactions between two types of robots include underwater sensor deployment and relocation, energy and data exchange, and acoustic localisation aiding. Hardware capabilities of each vehicle are described in detail. Inter-agent communication is split into two layers: surface and underwater communication. Surface communication utilises wireless communication using WiFi routers configured for decentralised routing. Underwater communication mainly uses acoustic communication which, when used within a large swarm, poses a challenging task because of high probability of interference and data loss. The acoustic communication protocol used to prevent these issues is presented in detail. Finally, more complex functionalities of the robotic swarm are presented, including several results from real-life experiments.
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He, Jun, Jie Li, Xiaowu Zhu, Shangkun Xiong y Fangjiong Chen. "Design and Analysis of an Optical–Acoustic Cooperative Communication System for an Underwater Remote-Operated Vehicle". Applied Sciences 12, n.º 11 (30 de mayo de 2022): 5533. http://dx.doi.org/10.3390/app12115533.
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Underwater wireless communication technology plays a key role in the field of marine equipment technology. In this paper, we experimentally demonstrate an underwater optical–acoustic cooperative communication platform for an underwater wireless data transmission system. The system utilizes an underwater Remote-Operated Vehicle (ROV) as a carrier, equipped with LEDbased optical communication and acoustic communication modems. In particular, the system applies optical communication to transmit large-scale data and applies acoustic communication to provide acoustic-assisted signaling exchange before optical transmission and Automatic Repeat Request (ARQ) during optical transmission. By experimentally measuring the transmission distance under different water quality conditions, we found that the system can achieve a data rate of up to 5 Mb/s over a laboratory underwater channel of 7.6 m. By comparing the attenuation coefficients for the outdoor underwater environment with that in clear seawater, we estimate that the achievable link distance in clear seawater can reach 11 m with a data rate of 3.125 MB/s. The proposed system takes both implementation complexity and cost into consideration and also provides significant guidance for future real-time high-speed underwater optical–acoustic communications.
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Wang, Zixiang, Fan Zhen, Senlin Zhang, Meiqin Liu y Qunfei Zhang. "Jamming-resilient algorithm for underwater cognitive acoustic networks". International Journal of Distributed Sensor Networks 13, n.º 8 (agosto de 2017): 155014771772630. http://dx.doi.org/10.1177/1550147717726309.
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Due to the limit spectrum resource in the underwater acoustic networks, underwater cognitive acoustic communication is a promising technique. The channel sharing mechanism in cognitive networks can improve the communication capacity efficiently. Jamming attack is a common deny of service attack in cognitive networks. In the underwater cognitive acoustic networks, the anti-jamming problem is quite different from cognitive radio networks. It calls for an effective anti-jamming strategy in the cognitive acoustic channel access. In this article, we propose an online learning anti-jamming algorithm called multi-armed bandit–based acoustic channel access algorithm to achieve the jamming-resilient cognitive acoustic communication. The imperfect channel sensing and the constraints of underwater acoustic communication are considered in the anti-jamming game. Under different kinds of jamming attacks, the channel utilization can be improved with our jamming-resilient approach.
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Naresh Kumar, D. y . "Securing Underwater Wireless Communication Networks". International Journal of Engineering & Technology 7, n.º 2.23 (20 de abril de 2018): 505. http://dx.doi.org/10.14419/ijet.v7i2.23.15344.
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Underwater remote correspondence systems (UWCNs) are especially defenseless against vindictive assaults because of the high piece blunder rates, huge and variable proliferation deferrals, and low data transmission of acoustic channels. The special attributes of the Underwater acoustic correspondence channel and the contrasts between Underwater sensor systems and their ground-based partners require the improvement of productive and solid security instruments. In this class, an entire review of security for UWCNs is exhibited, and the exploration challenge for secure correspondence in this condition is sketched out.UWCNs incorporate sensors and self-ruling Underwater vehicles (AUVs) that collaborate to perform particular applications, for example, Underwater observing. Coordination and data sharing amongst sensors and AUVs make the arrangement of security testing.
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Zhu, Yun Hang y Zhi Hui Deng. "The Application of RAKE Receiving Technology in the Underwater SS Communication". Applied Mechanics and Materials 513-517 (febrero de 2014): 4248–52. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.4248.
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In recent years, the strategic significance of the oceans is growing as well as its research and development needs. The underwater wireless communication is becoming more and more important. The underwater acoustic communication is one of the few mediums which can conduct the underwater transmission over a long distance, and the multipath effect is the major obstacle of affecting the systems high speed and high reliability. The characteristics of underwater acoustic fading and coherent multi-path channel are studied, and the model of underwater acoustic spreading spectrum (SS) communication system is established. The affect of coding technique on the systems performance are analyzed in detail. The improved RAKE receiving technical solution is put forward, whose simulation analysis and data in different combining ways are given. It is proved that the scheme can better solve the problem of multipath interference in underwater acoustic transmission.
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Guo, Xiaopeng, Biao Wang, Yunan Zhu, Zide Fang y Zhaoyue Han. "Hamming Distance Optimized Underwater Acoustic OTFS-IM Systems". Entropy 25, n.º 7 (24 de junio de 2023): 972. http://dx.doi.org/10.3390/e25070972.
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The orthogonal time frequency space (OTFS) modulation technique can provide reliable communication in time-varying channels. Due to the dispersive characteristics of underwater acoustic channels, this paper proposes an OTFS-IM underwater acoustic communication system based on Hamming distance optimization to reduce the impact of dispersion in underwater acoustic communication. Firstly, the OTFS-IM underwater acoustic communication system is introduced, which introduces index modulation into the Delay–Doppler (DD) domain to make the OTFS system have stronger anti-Delay–Doppler capability. In contrast, since there is index sequence redundancy in a specific index combination, a Hamming distance optimization model is used to eliminate the redundant combination in the specific index combination sequence and further improve the bit error rate performance of the system. In addition, the Hamming distance optimized OTFS-IM underwater acoustic communication system is verified by simulation analysis. The results show that the proposed Hamming distance optimized OTFS-IM can achieve more reliable bit error rate performance.
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Wu, Shijun, Puzhe Zhou, Canjun Yang, Yushi Zhu y Hui Zhi. "A Novel Approach for Underwater Vehicle Localization and Communication Based on Laser Reflection". Sensors 19, n.º 10 (15 de mayo de 2019): 2253. http://dx.doi.org/10.3390/s19102253.
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This study presents a device for tracking, locating and communicating underwater vehicles as they work near the seabed. The system includes a base station placed on the seabed and a reflective module mounted on a hybrid underwater profiler (HUP). The base station localizes and communicates with the HUP working near the seabed based on laser reflections of corner cube retroreflectors. A tracking method based on the particle filter algorithm is then presented. Localization is performed using the least-squares method with refraction compensation. Lost tracking links are retrieved via a recovering approach based on the interpolation method. Finally, a communication method using a modulating retroreflector installed on the reflection module is proposed. The proposed tracking, localization, and communication approach provides higher localization accuracy with lower power consumption at low cost compared with the commonly used acoustic methods. The effectiveness of the proposed approach was clarified via tracking, localization, and communication experiments.
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Ahmad y Chang. "Downlink Power Allocation Strategy for Next-Generation Underwater Acoustic Communications Networks". Electronics 8, n.º 11 (6 de noviembre de 2019): 1297. http://dx.doi.org/10.3390/electronics8111297.
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The increasing interest in next-generation underwater acoustic communications networks is due to vast investigation of oceans for oceanography, commercial operations in maritime areas, military surveillance, and more. A surface buoy or underwater base station controller (UBSC) communicates with either transceivers or underwater base stations (UBSs) via acoustic links. Transceivers further communicate with underwater sensor nodes using acoustic links. In this paper, we employ a downlink (DL) power allocation (PA) strategy using an orthogonal frequency-division multiple access (OFDMA) technique for underwater acoustic communications (UAC) networks. First, we present an approach to power offsets using three kinds of pilot spacing and apply the power boosting (PB) concept on orthogonal frequency-division multiplexing (OFDM) symbols for the UAC network. Secondly, we draw the block error rate (BLER) curves from link-level simulation (LLS) and analyze the signal-to-noise ratio (SNR) for both PA and non-PA strategies. Lastly, we adopt the best PB for system-level simulation (SLS) and compare the throughput and outage performance for PA and non-PA strategies. Hence, the simulation results confirm the effectiveness of the DL PA strategy for UAC networks.
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Rychen, Jörg, Julie Semoroz, Alexander Eckerle, Richard HR Hahnloser y Rébecca Kleinberger. "Full-duplex acoustic interaction system for cognitive experiments with cetaceans". Interaction Studies 24, n.º 1 (28 de agosto de 2023): 66–86. http://dx.doi.org/10.1075/is.22039.ryc.
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Abstract Cetaceans show high cognitive abilities and strong social bonds. Their primary sensory modality to communicate and sense the environment is acoustics. Research on their echolocation and social vocalizations typically uses visual and tactile systems adapted from research on primates or birds. Such research would benefit from a purely acoustic communication system to better match their natural capabilities. We argue that a full duplex system, in which signals can flow in both directions simultaneously is essential for communication research. We designed and implemented a full duplex system to acoustically interact with cetaceans in the wild, featuring digital echo-suppression. We pilot tested the system in Arctic Norway and achieved an echo suppression of 18 dB. We discuss the limiting factors and how to improve the echo suppression further. The system enabled vocal interaction with the underwater acoustic scene by allowing experimenters to listen while producing sounds. We describe our motivations, then present our pilot deployment and give examples of initial explorative attempts to vocally interact with wild orcas and humpback whales.
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Yao, Xiaohui, Honghui Yang y Meiping Sheng. "Automatic Modulation Classification for Underwater Acoustic Communication Signals Based on Deep Complex Networks". Entropy 25, n.º 2 (9 de febrero de 2023): 318. http://dx.doi.org/10.3390/e25020318.
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Automatic modulation classification (AMC) is an important method for monitoring and identifying any underwater communication interference. Since the underwater acoustic communication scenario is full of multi-path fading and ocean ambient noise (OAN), coupled with the application of modern communication technology, which is usually susceptible to environmental influences, automatic modulation classification (AMC) becomes particularly difficult when it comes to an underwater scenario. Motivated by the deep complex networks (DCN), which have an innate ability to process complex data, we explore DCN for AMC of underwater acoustic communication signals. To integrate the signal processing method with deep learning and overcome the influences of underwater acoustic channels, we propose two complex physical signal processing layers based on DCN. The proposed layers include a deep complex matched filter (DCMF) and deep complex channel equalizer (DCCE), which are designed to remove noise and reduce the influence of multi-path fading for the received signals, respectively. Hierarchical DCN is constructed using the proposed method to achieve better performance of AMC. The influence of the real-world underwater acoustic communication scenario is taken into account; two underwater acoustic multi-path fading channels are conducted using the real-world ocean observation dataset, white Gaussian noise, and real-world OAN are used as the additive noise, respectively. Contrastive experiments show that the AMC based on DCN can achieve better performance than the traditional deep neural network based on real value (the average accuracy of the DCN is 5.3% higher than real-valued DNN). The proposed method based on DCN can effectively reduce the influence of underwater acoustic channels and improve the AMC performance in different underwater acoustic channels. The performance of the proposed method was verified on the real-world dataset. In the underwater acoustic channels, the proposed method outperforms a series of advanced AMC method.
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Li, Fulong, Xiaohong Shen, Ling Wang y Haiyan Wang. "Research of Mobile Underwater Acoustic Communication of M-Ary Combining FDM and Piecewise-LFM". Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, n.º 4 (agosto de 2019): 704–13. http://dx.doi.org/10.1051/jnwpu/20193740704.
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Aiming at the countering doppler shift, a mobile underwater acoustic communication scheme of M-ary via FDM-PLFM is proposed. The cross-correlation between piecewise linear frequency modulation(PLFM) and traditional LFM signal is analyzed based on the cross-correlation function. Combining with frequency division multiplexing(FDM), the spectrum utilization of traditional underwater acoustic LFM communication scheme is improved. With the underwater acoustic LFM communication scheme, the new scheme does not require the doppler frequency shift compensation at the low doppler shift. The simulation results show that the present scheme has lower bit error rate than that for the traditional underwater acoustic M-ary LFM communication method under higher data rate conditions.
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Kohli, Sheena. "Sensor Hop-based Energy Efficient Networking Approach for Routing in Underwater Acoustic Communication". Journal of Telecommunications and Information Technology, n.º 1 (30 de marzo de 2017): 44–49. http://dx.doi.org/10.26636/jtit.2017.1.649.
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Underwater Wireless Sensor Networks are deployed to explore the world under the water, measure different parameters and communicate the data to the surface, in the widespread applications. The main operating technology of these networks is the acoustic communication. The communication among the sensors and finally to the surface station requires a routing protocol. The sensors being battery limited and unfeasible to be replaced under the water requires an energy efficient routing protocol. Clustering imparted in routing is an energy saving technique in sensor networks. The routing may involve single or multi hop communication in the sensor networks. The paper gives a comparative study of the benchmark protocol multi-hop LEACH with the proposed Sensor Hop-based Energy Efficient Networking Approach (SHEENA) for the shallow as well as deep water in three dimensional Underwater Wireless Sensor Networks. The network energy model for the Underwater Wireless Sensor Networks is based among the different acoustic channel characteristics. The proposed approach is found to give better response.
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Liu, Tao, Jian Gan Wang y Si Guang Zong. "Experimental Investigation on Underwater Opto-Acoustic Communication". Applied Mechanics and Materials 143-144 (diciembre de 2011): 653–57. http://dx.doi.org/10.4028/www.scientific.net/amm.143-144.653.
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The underwater opto-acoustic communication system for directional acoustic communication between an in-air platform and a submerged platform operating is important. The paper presents a new method to solve this problem with opto-acoustic technology, which combines high-energy laser, the opto-acoustic transmitter that optical energy is converted to acoustic energy at the water surface. The laser-based transmitter provides a versatile method for generating underwater sound. The acoustic pressure is linearly proportional to the laser power. The paper designed an experimental measurement system for the opto-acoustic communication. It made experiments for study on the waveform and spectrum characteristics of opto-acoustic signals. The paper also discuss the acoustic wave after optical breakdown in water with Nd:YAG laser pulses. The opto-acoustic signals can controll by adjusting the laser's parameters. The conclusion is that the opto-acoustic communication has some technical advantages. This system presents a change in the way communicational from the air.
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Dey, Indrakshi y Nicola Marchetti. "Channel Emulator Framework for Underwater Acoustic Communications". Applied Sciences 13, n.º 9 (8 de mayo de 2023): 5818. http://dx.doi.org/10.3390/app13095818.
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In this paper, we develop a tractable mathematical model and an emulation framework for communicating information through water using acoustic signals. Water is considered one of the most complex media to model due to its vastness and variety of characteristics, which depend on the scenario, the type of water body (lakes, rivers, tanks, sea, etc.), and the geographical location of the water body being considered. Our proposed mathematical model involves the concept of damped harmonic oscillators to represent the medium (water); Milne’s oscillator technique is used to map the interaction between the acoustic signal and water. Wave equations formulated for acoustic pressure and acoustic wave velocity are employed to characterise the travelling acoustic signal. The signal strength, phase shift, and time delay generated from the mathematical model are then inputted into a Simulink-based emulator framework to generate channel samples and channel impulse responses. The emulator utilises the wide sense stationary uncorrelated scattering (WSSUS) assumption and a finite sum-of-sinusoids (SOS) approach with a uniformly distributed phase to generate the channel samples. By utilising this emulator platform, it becomes feasible to generate profiles for amplitude variation, the Doppler shift, and spread experienced by any travelling signal in various underwater communication scenarios. Such a platform can be employed to simulate different communication scenarios, underwater network topologies, and data for training various learning models. Additionally, it can predict the performance of different modulation, multiplexing, error correction, and multi-access techniques for underwater acoustic communication (UWAC) systems.
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Yang, Shaojian, Yimu Yang, Xingbin Tu, Xuesong Lu, Wei Yan y Fengzhong Qu. "Direct acoustic communication between underwater and airborne nodes". Journal of the Acoustical Society of America 154, n.º 4_supplement (1 de octubre de 2023): A308. http://dx.doi.org/10.1121/10.0023622.
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Direct acoustic communication between underwater and airborne nodes has always been considered unfeasible due to the energy loss caused by the strong surface reflection of sound waves. However, contrary to popular belief, our study demonstrates that underwater transducers can effectively transmit detectable acoustic signals in the air. To investigate this phenomenon, we conducted an experiment involving the deployment of an underwater transducer at a depth of 1 m, while an unoccupied aerial vehicle equipped with a voice recorder was positioned at various altitudes ranging from 2 to 30 m and horizontal distances of 0–30 m. Sound pressure levels were measured at 20 different positions within the frequency range of 10–20kHz, and orthogonal frequency division multiplex acoustic communication signals were recorded at specific positions. Our findings reveal the successful establishment of a direct acoustic communication link between the water and air interface, achieving a data rate of 4.565 kbps. This study opens up new possibilities for practical applications in underwater-to-air communication systems.
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van Walree, Paul A. y Roald Otnes. "Ultrawideband Underwater Acoustic Communication Channels". IEEE Journal of Oceanic Engineering 38, n.º 4 (octubre de 2013): 678–88. http://dx.doi.org/10.1109/joe.2013.2253391.
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Wang, Jianping, Lijuan Ma y Wei Chen. "Design of underwater acoustic sensor communication systems based on software-defined networks in big data". International Journal of Distributed Sensor Networks 13, n.º 7 (julio de 2017): 155014771771967. http://dx.doi.org/10.1177/1550147717719672.
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The application based on big data is an important development trend of underwater acoustic sensor networks. However, traditional underwater acoustic sensor networks rely on the hardware infrastructure. The flexibility and scalability cannot be satisfied greatly. Due to the low performance of underwater acoustic sensor networks, it creates significant barriers to the implementation of big data. Software-defined network is regarded as a new infrastructure of next-generation network. It offers a novel solution for designing underwater acoustic sensor networks of high performance. In this article, a software-defined network–based solution is proposed to build the architecture of underwater acoustic sensor networks in big data. The design procedures of the data plane and control plane are described in detail. In the data plane, the works include the hardware design of OpenFlow-based virtual switch and the design of the physical layer based on software-defined radio. The hierarchical clustering technology and the node addressing techniques for designing media access control layer are well introduced. In the control plane, exploiting the hardware of the controller and designing the core module of controllers are presented as well. Through the study, it is supposed to maximize the capacity of underwater acoustic sensor networks, reduce the management complexity, and provide critical technical support for the high-performance underwater acoustic sensor networks.
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Zhou, Liu, Nie, Yang, Zhang y Ma. "M-ary Cyclic Shift Keying Spread Spectrum Underwater Acoustic Communications Based on Virtual Time-Reversal Mirror". Sensors 19, n.º 16 (16 de agosto de 2019): 3577. http://dx.doi.org/10.3390/s19163577.
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Underwater acoustic communications are challenging because channels are complex, and acoustic waves when propagating in the ocean are subjected to a variety of interferences, such as noise, reflections, scattering and so on. Spread spectrum technique thus has been widely used in underwater acoustic communications for its strong anti-interference ability and good confidentiality. Underwater acoustic channels are typical coherent multipath channels, in which the inter-symbol interference seriously affects the performance of underwater acoustic communications. Time-reversal mirror technique utilizes this physical characteristic of underwater acoustic channels to restrain the inter-symbol interference by reconstructing multipath signals and reduce the influence of channel fading by spatial focusing. This paper presents an M-ary cyclic shift keying spread spectrum underwater acoustic communication scheme based on the virtual time-reversal mirror. Compared to the traditional spread spectrum techniques, this method is more robust, for it uses the M-ary cyclic shift keying spread spectrum to improve the communication rate and uses the virtual time-reversal mirror to ensure a low bit error rate. The performance of this method is verified by simulations and pool experiments.
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Vicerra, Ryan Rhay P. y Elmer P. Dadios. "Slime Mold Inspired Swarm Robot System for Underwater Wireless Data Communication". Journal of Advanced Computational Intelligence and Intelligent Informatics 20, n.º 1 (19 de enero de 2016): 92–99. http://dx.doi.org/10.20965/jaciii.2016.p0092.
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Swarm robotics is a collection of mobile robots that displays swarm behavior. This paper presents a simulator of slime mold amoeba inspired swarm robot for underwater wireless communication system. The slime mold inspired robotic swarm is used to overcome the challenges of transmitting data in a large underwater environment. Underwater communication systems today are primarily acoustic technology and characterized by limited and distance dependent bandwidth, presence of multipath, and low speed of sound propagation. The robots navigate and seek the shortest path creating a virtual connection between the data transmitter and receiver similar to the foraging behavior of swarms. Each individual robot going back and forth from the transmitter to the receiver and vice-versa acts as a “physical” carrier of the data. Swarm robots navigate using swarm level intelligence based on the signal propagation technique used by slime mold amoeba aggregation using acoustics communication. The robot swarm system is developed, simulated and tested using the coded simulator. Using the slime mold inspired swarm robot system; the simulation successfully performed the data “foraging” scenario and showed the ability of the swarm to provide a virtual link in an underwater wireless communication network.
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Wang, Haoyang. "Channel characteristics of underwater optical communication system". Applied and Computational Engineering 12, n.º 1 (25 de septiembre de 2023): 135–44. http://dx.doi.org/10.54254/2755-2721/12/20230309.
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Underwater communication technology has seen significant development in recent years, with a focus on finding efficient and secure techniques for exploring the underwater world. While acoustic and electromagnetic waves have limitations in water, the use of optical communication has become a focus of research due to its high bandwidth and low delay. Research has shown that blue and green lights are absorbed less than other wavelengths in water, making them suitable for underwater optical communication. In recent years, people have been working with optical communication in harsh environments. The optical system and the acoustic system have been combined to achieve certain development. Several high-speed underwater laser transmission systems have also been developed, with varying transfer rates and distances. This paper focuses on the theory of underwater optical systems and their communication channel characteristics.
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E-Fatima, Shan y Monika Tripathi. "PERFORMANCE ENHANCEMENT OF UNDERWATER ACOUSTIC COMMUNICATION USING DEEP LEARNING APPROACH". International Journal of Advanced Research 10, n.º 08 (31 de agosto de 2022): 704–14. http://dx.doi.org/10.21474/ijar01/15225.
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This research aims to improve underwater acoustic communication using deep learning. Due to an increase in undersea operations, dependable communication systems have become more important. The undersea environments complexity reduces the efficacy of underwater audio communication, despite its widespread use. Using mathematical equations and approximations, the underwater sound pathway has been modeled. These projects aim to enhance underwater communication systems by better understanding the underwater audio channel. In this study, we investigate the abilities of device learning and deep studying to investigate and accurately replicate the underwater acoustic channel by making use of real-world underwater data. This is done by analyzing the results of the study. The information has been compiled with the aid of using a combination of strategies, which include machine learning and in-depth reading. In particular, the Deep Neural Community (DNN) and long quick term memory (LSTM) modeling strategies are used in order to achieve the goal of simulating the underwater audio channel. The results of the trials demonstrate that these models are capable of accurately modeling the underwater acoustic communication channel. Furthermore, the findings suggest that deep learning models, particularly LSTM, are better models in terms of mean absolute percentage error. The vast majority of the currently available UWSN routing protocols use a classical routing strategy.
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Eom. "Algorithm and Experimental Verification of Underwater Acoustic Communication Based on Passive Time-Reversal Mirror". Journal of the Acoustical Society of Korea 33, n.º 6 (2014): 392. http://dx.doi.org/10.7776/ask.2014.33.6.392.
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Xu, Haiyun, Bin Wang y Yuting Meng. "The "4Rs" Teaching Method in Underwater Acoustic Communication Systems Course". Advances in Social Development and Education Research 1, n.º 1 (1 de diciembre de 2023): 115. http://dx.doi.org/10.61935/asder.1.1.2023.p115.
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According to the training goal of underwater acoustic engineering in Information Engineering University, we find the characteristics of underwater acoustic communication systems, summarize the experience during the years of teaching students practice, and then propose the teaching method of "underwater acoustic communication system" course, which is summarized as "4Rs". This paper firstly describes the meanings of "4Rs", which is suitable for our students. Then, we show the teaching contents and what the students can learn. And finally, we tell the implementation ideas of 4Rs teaching method, and through the consecutive practical teaching training, we can have many favorable teaching results.
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Danielis, Peter, Helge Parzyjegla, Mostafa Assem Mohamed Ali y Frank Sill Torres. "Simulation model for energy consumption and acoustic underwater communication of autonomous underwater vehicles". WMU Journal of Maritime Affairs 21, n.º 1 (29 de noviembre de 2021): 89–107. http://dx.doi.org/10.1007/s13437-021-00253-z.
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AbstractRecently, cooperative autonomous underwater vehicles (AUVs) have been deployed in application areas such as surveillance and protection of maritime infrastructures for inspection and monitoring purposes. These cooperative methodologies require wireless transmission of data between the different AUVs operating in the underwater environment. Communication over ranges exceeding 100 m exclusively relies on underwater acoustic communication. However, the propagating acoustic waves suffer from several challenges due to the presence of path loss, multi-path propagation, the slow and variant propagation speed, background noise, and Doppler distortion. Since the power supply of the AUVs is limited, communication must be very energy efficient and energy constraints have to be known to be able to plan the mission of AUVs. Due to the difficulties of real experiments, the modeling and simulation of the energy consumption and underwater acoustic communication play an essential role in studying and developing these systems. We provide a modular simulation model for the energy consumption and acoustic underwater communication of AUVs implemented in the network simulator OMNeT++ using the INET framework. More specifically, we extend several INET modules in such a way as to reflect the characteristics of AUVs and underwater communication. We study and analyze the AUVs’ energy consumption and dependence of the message quality on different properties such as those mentioned above.
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Yu, Yang, Jie Shi, Ke He y Peng Han. "The Control Packet Collision Avoidance Algorithm for the Underwater Multichannel MAC Protocols via Time-Frequency Masking". Discrete Dynamics in Nature and Society 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/2437615.
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Establishing high-speed and reliable underwater acoustic networks among multiunmanned underwater vehicles (UUVs) is basic to realize cooperative and intelligent control among different UUVs. Nevertheless, different from terrestrial network, the propagation speed of the underwater acoustic network is 1500 m/s, which makes the design of the underwater acoustic network MAC protocols a big challenge. In accordance with multichannel MAC protocols, data packets and control packets are transferred through different channels, which lowers the adverse effect of acoustic network and gradually becomes the popular issues of underwater acoustic networks MAC protocol research. In this paper, we proposed a control packet collision avoidance algorithm utilizing time-frequency masking to deal with the control packets collision in the control channel. This algorithm is based on the scarcity of the noncoherent underwater acoustic communication signals, which regards collision avoiding as separation of the mixtures of communication signals from different nodes. We first measure the W-Disjoint Orthogonality of the MFSK signals and the simulation result demonstrates that there exists time-frequency mask which can separate the source signals from the mixture of the communication signals. Then we present a pairwise hydrophones separation system based on deep networks and the location information of the nodes. Consequently, the time-frequency mask can be estimated.
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Shahapur, Salma S., Rajashri Khanai y Dattaprasad A. Torse. "Performance Analysis of Error Control Codes for Underwater Wireless Acoustic Communication". Trends in Sciences 19, n.º 3 (20 de enero de 2022): 2164. http://dx.doi.org/10.48048/tis.2022.2164.
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In underwater acoustic communication, the information transmitted from 1 sensor node to another is corrupted due to errors persuaded by the noisy channel and other issues. To reduce the bit error rate, it is essential to propose suitable error regulator structure. In this paper, we simulate the performance analysis of Orthogonal Frequency Division Multiplexing Interleaver Division Multiple Access Multiple Input Multiple Output scheme with different channel codes to improve bit error rate performance. Bit error rate and consumed power are measured by communicating arbitrarily generated information through AWGN network. From the simulation results and assessment of the 2 divergent channel coding, 2 interleavers and 3 modulation techniques. We conclude that turbo codes with random interleaver and binary phase shift keying are best suitable to improve reliability performance for underwater wireless acoustic communication. To reduce the burst error in underwater acostic communication we propose an hybrid approach IDMA OFDM MIMO. BER performance is improved upto 10−6.
HIGHLIGHTS
In underwater acoustic communication to reduce bit error rate, we simulate the performance analysis of Orthogonal Frequency Division Multiplexing Interleaver Division Multiple Access Multiple Input Multiple Output scheme
We propose a hybrid approach with 2 divergent channel coding, 2 interleavers and 3 modulation techniques
Finally, we observe from simulation results that turbo code with binary phase shift keying and random interleaving improves bit error rate performance
GRAPHICAL ABSTRACT
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Onur, T. O. "Investigation of Parameters Affecting Underwater Communication Channel". Journal of Engineering Sciences 7, n.º 1 (2020): F39—F44. http://dx.doi.org/10.21272/jes.2020.7(1).f4.
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Underwater communication has become a widely studied area in recent years and showed great potential to be an area of research. Acoustic communication is often preferred in underwater communication due to its suitability for an underwater diffusion environment. However, in underwater communication, the physical and chemical properties of the water environment affect sound propagation. Therefore, determining and examining parameters affecting channel performance in underwater communication plays an essential role in inefficient communication. In this study, the effects of salinity, depth, noise, temperature, and frequency parameters for the underwater channel model are examined. By determining the effects of these parameters on spherical and cylindrical propagation, suitable propagation geometry and parameter values for an efficient channel are investigated. In light of the results obtained, in case of studying in a limited area, the path and absorption losses can be reduced by selecting cylindrical propagation as a geometrical propagation model, thereby an efficient channel model can be formed. Keywords: cylindrical propagation, spherical propagation, underwater communication channel, acoustic communication, path loss, absorption loss.
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Duane, Daniel, Byunggu Cho, Ankita D. Jain, Olav Rune Godø y Nicholas C. Makris. "The Effect of Attenuation from Fish Shoals on Long-Range, Wide-Area Acoustic Sensing in the Ocean". Remote Sensing 11, n.º 21 (23 de octubre de 2019): 2464. http://dx.doi.org/10.3390/rs11212464.
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Acoustics is the primary means of long-range and wide-area sensing in the ocean due to the severe attenuation of electromagnetic waves in seawater. While it is known that densely packed fish groups can attenuate acoustic signals during long-range propagation in an ocean waveguide, previous experimental demonstrations have been restricted to single line transect measurements of either transmission or backscatter and have not directly investigated wide-area sensing and communication issues. Here we experimentally show with wide-area sensing over 360° in the horizontal and ranges spanning many tens of kilometers that a single large fish shoal can significantly occlude acoustic sensing over entire sectors spanning more than 30° with corresponding decreases in detection ranges by roughly an order of magnitude. Such blockages can comprise significant impediments to underwater acoustic remote sensing and surveillance of underwater vehicles, marine life and geophysical phenomena as well as underwater communication. This makes it important to understand the relevant mechanisms and accurately predict attenuation from fish in long-range underwater acoustic sensing and communication. To do so, we apply an analytical theory derived from first principles for acoustic propagation and scattering through inhomogeneities in an ocean waveguide to model propagation through fish shoals. In previous experiments, either the attenuation from fish in the shoal or the scattering cross sections of fish in the shoal were measured but not both, making it impossible to directly confirm a theoretical prediction on attenuation through the shoal. Here, both measurements have been made and they experimentally confirm the waveguide theory presented. We find experimentally and theoretically that attenuation can be significant when the sensing frequency is near the resonance frequency of the shoaling fish. Negligible attenuation was observed in previous low-frequency ocean acoustic waveguide remote sensing (OAWRS) experiments because the sensing frequency was sufficiently far from the swimbladder resonance peak of the shoaling fish or the packing densities of the fish shoals were not sufficiently high. We show that common heuristic approaches that employ free space scattering assumptions for attenuation from fish groups can lead to significant errors for applications involving long-range waveguide propagation and scattering.
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Ji, Xulong. "Research on Underwater Wireless Acoustic Communication Routing Protocol". International Journal of Education and Humanities 7, n.º 1 (1 de febrero de 2023): 46–50. http://dx.doi.org/10.54097/ijeh.v7i1.4912.
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Due to the limitation of the communication range of sensor nodes, underwater nodes must transmit data to the water surface through routing mechanism. Therefore, the design of routing algorithm is related to the performance of the network, and the research of routing algorithm is necessary. However, underwater nodes are vulnerable to ocean turbulence and biological factors. The underwater environment is dynamic and complex, which greatly affects the acoustic channel, making the improvement of routing protocol a challenge. These factors lead to problems in underwater acoustic communication network, such as empty nodes, packet delivery rate, energy consumption, delay and other problems, and in the dynamic and complex seawater environment, the performance of acoustic network will be further reduced. This paper introduces some main routing algorithms, such as hollow node awareness algorithm, layer-based routing protocol; Opportunistic routing algorithm; Double-hop routing protocol, etc. These routing algorithms can solve some problems. Simulation shows that they have certain advantages in packet delivery rate, delay, network lifetime, etc.
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Pavlov, Ivan I., Vyacheslav F. Myshkin y Valery A. Khan. "ORGANIZATION OF AN UNDERWATER WIRELESS COMMUNICATION SYSTEM". T-Comm 18, n.º 1 (17 de enero de 2024): 4–12. http://dx.doi.org/10.36724/2072-8735-2024-18-1-4-12.
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The article discusses underwater wireless communication systems. Research in the field of underwater optical wireless communication system will allow developing science, industry, to find solutions to defense tasks and emergencies, to carry out remote monitoring of environmental pollution of the underwater world and control underwater objects and equipment of oilrigs, to conduct underwater research and much more. The purpose of the work is to develop a classification of the principles of construction and organization of underwater wireless communication, taking into account modern achievements and development of technologies in the field of underwater wireless communication systems, to assess the strengths and weaknesses of underwater acoustic, radio frequency and optical communication systems. It is shown that the underwater optical wireless communication system has a great potential to enhance the traditional underwater acoustic communication system and underwater radio frequency communication system due to the high speed of information transmission, low latency, lower power consumption and compact size. To select the equipment and organize the communication channel, a generalized classification of an underwater optical wireless communication system has been developed, depending on the routing protocols used, on the configuration of the communication channel, on the optical properties of water, on the type of water in which the transmission channel is organized, on the mobility of underwater vehicles and the coverage area, on the type of modulation used, the method of underwater communication and from the factors affecting the organization of the communication channel.
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Rani, Jansi J., S. Anusuya, B. Vidhya y Benedict M. Tephila. "A Study on Techniques of Underwater Optical Communication". Journal of Computational and Theoretical Nanoscience 16, n.º 2 (1 de febrero de 2019): 525–28. http://dx.doi.org/10.1166/jctn.2019.7763.
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In recent years, the higher data rate and a higher degree of accuracy in transmissions have been achieved through wireless communication technology. The underwater communication is one of the trending technologies in wireless communication. The underwater data transmission is carried out by the acoustic waves which produce vibrations of sounds during its transmission. These vibrations have disturbed the creatures present underwater and additionally it may cause some noise. The results of many recent researches have concluded that the vibrations produced by the acoustic waves cause the disturbances in the earth plates and due to which the natural calamities like tsunami, earthquakes etc., have been occurring. The underwater communication is mostly used for military applications and for the transmission of sensitive information within the shortest distance of a particular area. The use of acoustic waves produces a low data rate and increased time delay. In addition to that, these waves are unreliable and complex due to multipath propagations in water. The acoustic waves employ modulation techniques like FSK, PSK and OFDM for the data transmission and consume more energy and power. So lately, the transmission of data in underwater is carried out by using the optical waves. ON–OFF keying technique is most commonly used modulation technique with attractive features such as high data rate, less delay, low power consumption, energy saving, and better accuracy than the other techniques.
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Hong, Dae-Ki y Sunhee Kim. "An Interpolator of Underwater Sensor Node with Enhanced Frequency Response Characteristic". Journal of Computational and Theoretical Nanoscience 18, n.º 5 (1 de mayo de 2021): 1360–64. http://dx.doi.org/10.1166/jctn.2021.9600.
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The digital part of the transmitter for acoustic wave communication must perform a sampling rate up conversion before converting the baseband signal to the acoustic wave band signal. Because acoustic wave communication operates at a low frequency, the digital part of most underwater communication devices is designed as software using DSPs. Since underwater sensor nodes among underwater communication devices are scattered in the sea, the power supply to the nodes is not smooth, so low-power design is important. In this paper, we designed the interpolator hardware for the low-power underwater communication sensor node chip. The requirements for frequency characteristics for acoustic wave communication of underwater sensor nodes and the operating frequency of the system to be implemented were identified, and an interpolator capable of meeting them was modeled using Matlab. Since a CIC interpolator is implemented without a multiplier and has a small area, we used CIC interpolators. However, the CIC interpolator has a wide transition band and a large passband droop. On the other hand, since the frequency of acoustic wave is low, both the data bandwidth and channel spacing are narrow, so filtering of the data signal is important. Therefore, complementary filters were added to satisfy the frequency specifications of the underwater sensor nodes. The structure of the entire interpolator hardware is designed so that additional filters operate at as low a clock rate as possible and have a low filter order. A hardware was designed using verilog hdl and verified using ModelSim. The simulation results of the designed hardware were compared with Matlab results to confirm that the frequency specifications were satisfied. The designed interpolator will be replaced by the interpolator of the previously tested underwater sensor node designed using DSP and used for distributed underwater observation control networks.
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Kim, Sunhyo y Jee Woong Choi. "Optimal Deployment of Vector Sensor Nodes in Underwater Acoustic Sensor Networks". Sensors 19, n.º 13 (29 de junio de 2019): 2885. http://dx.doi.org/10.3390/s19132885.
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Underwater acoustic sensor networks have recently attracted considerable attention as demands on the Internet of Underwater Things (IoUT) increase. In terms of efficiency, it is important to achieve the maximum communication coverage using a limited number of sensor nodes while maintaining communication connectivity. In 2017, Kim and Choi proposed a new deployment algorithm using the communication performance surface, which is a geospatial information map representing the underwater acoustic communication performance of a targeted underwater area. In that work, each sensor node was a vertically separated hydrophone array, which measures acoustic pressure (a scalar quantity). Although an array receiver is an effective system to eliminate inter-symbol interference caused by multipath channel impulse responses in underwater communication environments, a large-scale receiver system degrades the spatial efficiency. In this paper, single-vector sensors measuring the particle velocity are used as underwater sensor nodes. A single-vector sensor can be considered to be a single-input multiple-output communication system because it measures the three directional components of particle velocity. Our simulation results show that the optimal deployment obtained using single-vector sensor nodes is more effective than that obtained using a hydrophone (three-channel vertical-pressure sensor) array.
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Campo-Valera, María, Ivan Felis-Enguix y Isidro Villó-Pérez. "Signal Processing for Parametric Acoustic Sources Applied to Underwater Communication". Sensors 20, n.º 20 (17 de octubre de 2020): 5878. http://dx.doi.org/10.3390/s20205878.
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For years, in the field of underwater acoustics, a line of research with special relevance for applications of environmental monitoring and maritime security has been developed that explores the possibilities of non-linear phenomena of sound propagation, especially referring to the so-called parametric effect or self-modulation. This article shows the results of using a new modulation technique based on sine-sweep signals, compared to classical modulations (FSK and PSK). For each of these modulations, a series of 16-bit strings of information with different frequencies and durations have been performed, with the same 200 kHz carrier wave. All of them have been tested in the Hydroacoustic Laboratory of the CTN and, through the application of cross-correlation processing, the limitations and improvements of this novel processing technique have been evaluated. This allows reaching better limits in discrimination of bits and signal-to-noise ratio used in underwater parametric acoustic communications.
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Zhao, Zichen y Zongxin Sun. "Short-Block-Length Low-Density Parity-Check Codes-Based Underwater Acoustic Spread-Spectrum Communication System". Electronics 12, n.º 18 (14 de septiembre de 2023): 3884. http://dx.doi.org/10.3390/electronics12183884.
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Low-density parity-check (LDPC) codes are commonly used in communication systems to improve the system performance, but LDPC codes takes too long for decoding, making communication inefficient and unsuitable for short-frame data transmission methods. In underwater acoustic channels, spread-spectrum communication becomes an effective way to realize long-distance communication. This paper combines short-block LDPC codes with a direct sequence spread spectrum and soft spread spectrum in underwater acoustic communication, addressing the problem of the inapplicability of conventional LDPC codes. The applicability of the proposed method in this paper is verified through simulation tests and pool experiments. The results indicate that the proposed communication system achieves lower bit error rates compared to the classical coding methods used in underwater acoustic spread-spectrum communication systems under the same channel conditions.
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Liu, Lanjun, Hao Zhao, Ming Li, Lin Zhou, Jiucai Jin, Jie Zhang, Zhichao Lv, Hui Ren y Jicun Mao. "Modelling and Simulation of Pseudo-Noise Sequence-Based Underwater Acoustic OSDM Communication System". Applied Sciences 9, n.º 10 (19 de mayo de 2019): 2063. http://dx.doi.org/10.3390/app9102063.
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Orthogonal signal division multiplex (OSDM) is an emerging signal modulation technology which has a lower peak-to-average power ratio (PAPR) and a flexible subcarrier system architecture. Particularly, it can be seen as a bridge between the single-carrier modulation and the orthogonal frequency division multiplexing (OFDM) modulation in the frequency domain. Aiming at the development trend and demand of underwater acoustic hybrid and adaptive modulation communication technology, a pseudo-noise (PN) sequence-based underwater acoustic OSDM communication system is proposed in this paper. A data frame structure with PN sequence is designed to solve the multipath and Doppler effect of underwater acoustic channel. On the basis of the PN sequence, a compressive sensing method based on the orthogonal matching pursuit (OMP) algorithm and the minimum mean square error (MMSE) algorithm is designed for channel estimation and equalization. On the basis of the system construction, the relationship among the OSDM vector length M, the OSDM subcarrier number N, and the underwater acoustic channel length is further studied for adaptive modulation of underwater acoustic communication. Finally, the proposed system is verified by simulation. The OSDM system has lower and controllable PAPR. When the OSDM vector length M is bigger than the channel length, and the system subcarrier flexibility is guaranteed, the bit error rate (BER) of the OSDM system is lower than that of the OFDM system and the single-carrier system. The PN sequence-based compressive sensing channel estimation and equalization with the OMP and MMSE algorithms has a good performance to resist the multipath effect of underwater acoustic channel.