• Current Optics and Photonics
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• v.6 no.1
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• pp.39-43
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• 2022

Underwater optical wireless communication (UOWC) is a good candidate for high-speed underwater wireless communication. In this work, we compare the performance of several modulation techniques for a UOWC system consisting of a light-emitting diode (LED) with an operating wavelength of 405 nm and a Si avalanche photodiode (APD). In this work, we consider six modulation schemes: 4-quadrature amplitude modulation (QAM), 8-QAM, quadrature phase shift keying (QPSK), binary phase shift keying (BPSK), on-off keying (OOK), and 4-pulse amplitude modulation (PAM). We also consider the cases of pure water and seawater for the working conditions. Our results show that 4-QAM and 8-QAM perform the best, in terms of communication distance and transmission power efficiency, for all water types considered.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.923-928
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• 2014

Communication underwater is severely limited when compared to communications in air because water is essentially opaque to electromagnetic radiation except in visible range. Acoustic systems are capable of long range communication, but offer limited data rates and significant latency due to the speed of sound in water. On the other hand, optical wireless communication has been proposed as one of the best alternatives to meet the requirements of the underwater observation and subsea monitoring systems. It will help In this study, we are developing an underwater optical communication system that integrates with a depot ship floating on the water. An interface between LED lighting communication system and Bluetooth module is presented to support the underwater-to-air communications. Error free image and text transmission at 3 m of water were achieved at bit rates of 230.4 kbps. This development effort will enhance infrastructure to efficiently interconnect between underwater wireless systems and command ship networks for underwater monitoring.

• Journal of Advanced Navigation Technology
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• v.23 no.1
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• pp.61-68
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• 2019

Underwater wireless light communication system is quite necessary to retrieve recorded data from underwater devices or the black box without taking back it body. In this paper, a research on the light sensor technology in underwater wireless light communication under turbid sea was studied. A noise source under turbid sea for light communication was analysed, and a sensor system for light sensing using the reference light signal to remove the noises and to improve the output swing power wasstudied. Also, an underwater communication system was manufactured to validate the good performance of the development system, and using the system, the good performance of the developed system was validated through the light communication test in the tank containing the turbid sea water was presented.

• Ocean Systems Engineering
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• v.8 no.1
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• pp.33-39
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• 2018

The paper presents a numerical underwater channel model developed in MATLAB for estimating the optical link budget between a light emitting diode (LED) based optical transmitter and a photo diode (PD) receiver when operated in the harbor, coastal and deep waters locations in the Bay of Bengal. The water samples are collected at different locations in the Bay of Bengal using a water sampler during an offshore research cruise. The optical attenuation, the main inherent parameter determining the range of the optical communication link is identified for the different waters using an underwater irradiance measurement system in the laboratory. The identified parameters are applied to the numerical model and found that a 10 W LED and a photo diode based system can provide the optical budget required for a horizontal underwater communication range of about 0.5, 14 and 35 m in the harbor, coastal and deep waters locations respectively. By increasing the transmitter power to 50 W, the operating range of the communication link could be increased up to 53 m in deep water locations in the Bay of Bengal.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.115-118
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• 2014

Underwater Wireless Communication System can be useful for research of quality of water, ocean resources exploration, analysis ocean environment and so on. However, there exist security threats including data loss, data forgery, and another variety of security threats, because of characteristics of water, various geographical factors, intended attack, etc. To solve these problem, in this paper, we propose a CCM-UW mode of operation modified form of CCM mode of operation, providing data confidentiality, integrity, origin authentication and anti-attack prevent, for the Underwater Wireless Communication System. By implementing CCM-UW in MACA protocol(Underwater Wireless Communication MAC Protocol) and measuring speed of communication, we confirm the applicability of the security and analyze the communication environment impact.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2643-2645
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• 2004

The underwater system autonomously is navigated by using the wireless communication system, which receives the control signal from surface ship. The study proposes the new media access control protocol for underwater vehicles network in the view of communication distance and as CSMA(Carrier Sense Multiple Access) for the existing networks is intended to communication network using the high speed media such as electric signal or microwave signal, and thus it may introduce the reduction in throughput when applying the protocols to underwater communication network.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.231-234
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• 2008

The paper proposed the new underwater wireless communication system fitted to non-linear acoustic channel. Generally, in non-linear acoustic channel, one used to do acoustic communication using parametric effect that is some effect caused from acoustic wave having frequency different of two primary acoustic wave frequency. In the paper, Offset PSK communication method fitted to non-linear acoustic channel was proposed, and it was demonstrated through simulations.

• The Journal of the Acoustical Society of Korea
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• v.23 no.2
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• pp.134-145
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• 2004

The study aims to develop the underwater wireless telephone system. The system is designed based on the underwater acoustic communication channel parameters such as ambient noise, multipath effect and diver breathing noise. The system adopts SSB modem and its carrier frequency is about 33 kHz in which ambient noise level is low and therefore a high S/N ratio is easily obtained. The source level of the transmitter is designed as 131 dB re 1μPa. Its intelligibility index of sentence shows as 80% or mure in the range of less than 300m in the sea trial.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.109-114
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• 2003

Wireless communication systems are inevitable for efficient underwater activities. Because of the poor propagation characteristics of light and electromagnetic waves, acoustic waves are generally used for the underwater wireless communication. Although there are many kinds of information type, visual images take an essential role especially for search and identification activities. For this reason, we developed an acoustic-based underwater image transmission system under a dual use technology project supported by MOCIE (Ministry of Commerce, Industry and Energy). For the application to complicated and time-varying underwater environments all-digital transmitter and receiver systems are investigated. Array acoustic transducers are used at the receiver, which have the center frequency of 32kHz and the bandwidth of 4kHz. To improve transmission speed and quality, various algorithms and systems are used. The system design techniques will be discussed in detail including image compression/ decompression system, adaptive beam- forming, fast RLS adaptive equalizer, ${\partial}/4$ QPSK (Quadrilateral Phase Shift Keying) modulator/demodulator, and convolution coding/ Viterbi. Decoding.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.579-582
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• 2016

Recently, wireless communication system has been widely used in a variety of fields along with the remarkable advancement of communication technology. Sound communication system in underwater wireless communication is utilized in underwater communication since it has better transmission capacity than the existing RF. However, sound communication system has the problems such as low speed communication, transmission delay and limited bandwidth, and the studies have been actively conducted on the visible light communication underwater to improve these problems. Therefore, the visible light communication underwater using ASK modulation is suggested for the effective communication in this article.