High bandwidth underwater optical communication
TL;DR: Results of Monte Carlo simulations over ocean water paths of several tens of meters indicate that optical communication data rates >1 Gbit/s can be supported and are compatible with high-capacity data transfer applications that require no physical contact.
Abstract: We report error-free underwater optical transmission measurements at 1 Gbit/s (109 bits/s) over a 2 m path in a laboratory water pipe with up to 36 dB of extinction. The source at 532 nm was derived from a 1064 nm continuous-wave laser diode that was intensity modulated, amplified, and frequency doubled in periodically poled lithium niobate. Measurements were made over a range of extinction by the addition of a Mg(OH)2 and Al(OH)3 suspension to the water path, and we were not able to observe any evidence of temporal pulse broadening. Results of Monte Carlo simulations over ocean water paths of several tens of meters indicate that optical communication data rates >1 Gbit/s can be supported and are compatible with high-capacity data transfer applications that require no physical contact.
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TL;DR: An up-to-date survey on FSO communication systems is presented, describing FSO channel models and transmitter/receiver structures and details on information theoretical limits of FSO channels and algorithmic-level system design research activities to approach these limits are provided.
Abstract: Optical wireless communication (OWC) refers to transmission in unguided propagation media through the use of optical carriers, i.e., visible, infrared (IR), and ultraviolet (UV) bands. In this survey, we focus on outdoor terrestrial OWC links which operate in near IR band. These are widely referred to as free space optical (FSO) communication in the literature. FSO systems are used for high rate communication between two fixed points over distances up to several kilometers. In comparison to radio-frequency (RF) counterparts, FSO links have a very high optical bandwidth available, allowing much higher data rates. They are appealing for a wide range of applications such as metropolitan area network (MAN) extension, local area network (LAN)-to-LAN connectivity, fiber back-up, backhaul for wireless cellular networks, disaster recovery, high definition TV and medical image/video transmission, wireless video surveillance/monitoring, and quantum key distribution among others. Despite the major advantages of FSO technology and variety of its application areas, its widespread use has been hampered by its rather disappointing link reliability particularly in long ranges due to atmospheric turbulence-induced fading and sensitivity to weather conditions. In the last five years or so, there has been a surge of interest in FSO research to address these major technical challenges. Several innovative physical layer concepts, originally introduced in the context of RF systems, such as multiple-input multiple-output communication, cooperative diversity, and adaptive transmission have been recently explored for the design of next generation FSO systems. In this paper, we present an up-to-date survey on FSO communication systems. The first part describes FSO channel models and transmitter/receiver structures. In the second part, we provide details on information theoretical limits of FSO channels and algorithmic-level system design research activities to approach these limits. Specific topics include advances in modulation, channel coding, spatial/cooperative diversity techniques, adaptive transmission, and hybrid RF/FSO systems.
1,749 citations
Cites background from "High bandwidth underwater optical c..."
...(WBAN) and wireless personal area network (WPAN) applications [30], underwater communications [31], [32]....
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TL;DR: An exhaustive overview of recent advances in underwater optical wireless communication is provided and a hybrid approach to an acousto-optic communication system is presented that complements the existing acoustic system, resulting in high data rates, low latency, and an energy-efficient system.
Abstract: Underwater wireless information transfer is of great interest to the military, industry, and the scientific community, as it plays an important role in tactical surveillance, pollution monitoring, oil control and maintenance, offshore explorations, climate change monitoring, and oceanography research. In order to facilitate all these activities, there is an increase in the number of unmanned vehicles or devices deployed underwater, which require high bandwidth and high capacity for information transfer underwater. Although tremendous progress has been made in the field of acoustic communication underwater, however, it is limited by bandwidth. All this has led to the proliferation of underwater optical wireless communication (UOWC), as it provides higher data rates than the traditional acoustic communication systems with significantly lower power consumption and simpler computational complexities for short-range wireless links. UOWC has many potential applications ranging from deep oceans to coastal waters. However, the biggest challenge for underwater wireless communication originates from the fundamental characteristics of ocean or sea water; addressing these challenges requires a thorough understanding of complex physio-chemical biological systems. In this paper, the main focus is to understand the feasibility and the reliability of high data rate underwater optical links due to various propagation phenomena that impact the performance of the system. This paper provides an exhaustive overview of recent advances in UOWC. Channel characterization, modulation schemes, coding techniques, and various sources of noise which are specific to UOWC are discussed. This paper not only provides exhaustive research in underwater optical communication but also aims to provide the development of new ideas that would help in the growth of future underwater communication. A hybrid approach to an acousto-optic communication system is presented that complements the existing acoustic system, resulting in high data rates, low latency, and an energy-efficient system.
859 citations
Cites background or methods from "High bandwidth underwater optical c..."
...Work done by authors in [54] and [56] is focused on channel time dispersion leading to ISI....
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...In [54], a 1 Gbps laser based communication over 2 m range has been demonstrated in laboratory environment....
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...Typical values of absorption and scattering coefficients [54]....
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...The effect of system design parameters like transmitter beam divergence and receiver aperture size is studied in [54] to quantify channel time dispersion in UOWC....
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...In [54], an externally modulated laser operating at 532 nm is used to establish 1 Gbps underwater optical link....
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TL;DR: This paper provides a comprehensive and exhaustive survey of the state-of-the-art UOWC research in three aspects: 1) channel characterization; 2) modulation; and 3) coding techniques, together with the practical implementations of UowC.
Abstract: Underwater wireless communications refer to data transmission in unguided water environment through wireless carriers, i.e., radio-frequency (RF) wave, acoustic wave, and optical wave. In comparison to RF and acoustic counterparts, underwater optical wireless communication (UOWC) can provide a much higher transmission bandwidth and much higher data rate. Therefore, we focus, in this paper, on the UOWC that employs optical wave as the transmission carrier. In recent years, many potential applications of UOWC systems have been proposed for environmental monitoring, offshore exploration, disaster precaution, and military operations. However, UOWC systems also suffer from severe absorption and scattering introduced by underwater channels. In order to overcome these technical barriers, several new system design approaches, which are different from the conventional terrestrial free-space optical communication, have been explored in recent years. We provide a comprehensive and exhaustive survey of the state-of-the-art UOWC research in three aspects: 1) channel characterization; 2) modulation; and 3) coding techniques, together with the practical implementations of UOWC.
790 citations
Cites background or methods or result from "High bandwidth underwater optical c..."
...TABLE III TYPICAL VALUES OF a(λ), b(λ), AND c(λ) FOR DIFFERENT WATER TYPES [30], [37], [53], [54]...
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...In order to verify the Monte Carlo approach for UOWC channel modeling, Hanson and Radic [53] made a comparison between the results of Monte Carlo simulation and laboratory...
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...In several LD-based UOWC applications, optical diffusers are implemented to reduce the system pointing requirements [53], [150], [151]....
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...In order to verify the Monte Carlo approach for UOWC channel modeling, Hanson and Radic [53] made a comparison between the results of Monte Carlo simulation and laboratory experiments....
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TL;DR: This paper is an overview of the OWC systems focusing on visible light communications, free space optics, transcutaneous O WC, underwater OWC, and optical scattering communications.
Abstract: New data services and applications are emerging continuously and enhancing the mobile broadband experience. The ability to cope with these varied and sophisticated services and applications will be a key success factor for the highly demanding future network infrastructure. One such technology that could help address the problem would be optical wireless communications (OWC), which presents a growing research interest in the last few years for indoor and outdoor applications. This paper is an overview of the OWC systems focusing on visible light communications, free space optics, transcutaneous OWC, underwater OWC, and optical scattering communications.
377 citations
01 Oct 2008
TL;DR: Recommendations are made for the selection of communication carriers for UWSNs with engineering countermeasures that can possibly enhance the communication efficiency in specified underwater environments.
Abstract: This paper reviews the physical fundamentals and engineering implementations for efficient information exchange via wireless communication using physical waves as the carrier among nodes in an underwater sensor network (UWSN). The physical waves under discussion include sound, radio, and light. We first present the fundamental physics of different waves; then we discuss and compare the pros and cons for adopting different communication carriers (acoustic, radio, and optical) based on the fundamental first principles of physics and engineering practice. The discussions are mainly targeted at underwater sensor networks (UWSNs) with densely deployed nodes. Based on the comparison study, we make recommendations for the selection of communication carriers for UWSNs with engineering countermeasures that can possibly enhance the communication efficiency in specified underwater environments. Copyright © 2008 John Wiley & Sons, Ltd.
376 citations
References
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01 May 2005
TL;DR: In this paper, several fundamental key aspects of underwater acoustic communications are investigated and a cross-layer approach to the integration of all communication functionalities is suggested.
Abstract: Underwater sensor nodes will find applications in oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation and tactical surveillance applications. Moreover, unmanned or autonomous underwater vehicles (UUVs, AUVs), equipped with sensors, will enable the exploration of natural undersea resources and gathering of scientific data in collaborative monitoring missions. Underwater acoustic networking is the enabling technology for these applications. Underwater networks consist of a variable number of sensors and vehicles that are deployed to perform collaborative monitoring tasks over a given area. In this paper, several fundamental key aspects of underwater acoustic communications are investigated. Different architectures for two-dimensional and three-dimensional underwater sensor networks are discussed, and the characteristics of the underwater channel are detailed. The main challenges for the development of efficient networking solutions posed by the underwater environment are detailed and a cross-layer approach to the integration of all communication functionalities is suggested. Furthermore, open research issues are discussed and possible solution approaches are outlined. � 2005 Published by Elsevier B.V.
2,864 citations
TL;DR: In this article, a theoretical study on the optimization of second harmonic generation (SHG) and parametric generation (PG) by a laser beam in a uniaxial nonlinear crystal is presented.
Abstract: A theoretical study is presented on the optimization of second harmonic generation (SHG) and parametric generation (PG) by a laser beam in a uniaxial nonlinear crystal. Numerically computed curves show the dependence of the SHG power, and the reciprocal of the PG threshold power, on the parameter l/b, where l is the optical path length in the crystal and b is the confocal parameter (determined by the focal length of the focusing lens and the minimum radius of the laser beam, assumed to be in the TEM00 mode of an optical resonator). The calculations take full account of diffraction and double refraction. In the absence of double refraction, the optimum focusing condition is found to be l/b=2.84. For PG the optimization of the crystal length l is also discussed, and curves are given showing the dependence of the threshold on l for the case in which signal and idler have the same losses. It is shown that the computed functions are also relevant to the mixing of two Gaussian beams and to parametric amplificat...
1,700 citations
01 Oct 1972
TL;DR: In this paper, volume scattering functions for three general types of natural ocean waters have been obtained and are presented and are used for beam transmission in laboratory experiments using sea water, filtered fresh water, and artificial scattering and absorbing agents.
Abstract: Volume scattering functions for three general types of natural ocean waters have been obtained and are presented here. The three types of water are (1) deep clear oceanic water, (2) nearshore ocean water, and (3) very turbid harbor water. Also included are the results of laboratory experiments using sea water, filtered fresh water, and artificial scattering and absorbing agents. The beam transmission was obtained for all waters investigated. A brief description of the instruments used is given.
787 citations
17 Oct 2005
TL;DR: In this paper, the basic design issues for underwater optical communications systems with environmental noise were considered, and the effects of environmental noise such as background solar radiation, which typically limits performance of these systems were also considered.
Abstract: Acoustic systems may provide suitable underwater communications because sound propagates well in water. However, the maximum data transmission rates of these systems in shallow littoral waters are ~10 kilobits per second (kbps) which may be achieved only at ranges of less than 100 m. Although underwater (u/w) wireless optical communications systems can have even shorter ranges due to greater attenuation of light propagating through water, they may provide higher bandwidth (up to several hundred kbps) communications as well as covertness. To exploit these potential advantages, we consider the basic design issues for u/w optical communications systems in this paper. In addition to the basic physics of u/w optical communications with environmental noise, we consider system performance with some state-of-the-art commercial off-the-shelf (COTS) components, which have promise for placing u/w optical communications systems in a small package with low power consumption and weight. We discuss light sources which show promise for u/w optical transmitters such as laser diodes (LDs) and light emitting diodes (LEDs). Laser diodes with their output frequency shifted into the 500- to 650-nm range can emit more energy per pulse than LEDs but are more expensive. Currently, LEDs emit substantial amounts of light and are typically very inexpensive. Also, COTS photodiodes can be used as detectors which can respond to pulses several nanoseconds wide. Transmitter broadcast angles and detector fields of view (FOVs) with pointing considerations are discussed. If the transmitter broadcast angle and the detector FOV are both narrow, the signal-to-noise ratio (SNR) of the received pulse is higher but the pointing accuracy of transmitter and receiver is critical. If, however, the transmitter broadcast angle and/or the detector FOV is wide, pointing is less critical but SNR is lower and some covertness may be lost. The propagation of the transmitted light in various clear oceanic and turbid coastal water types is considered with range estimates for some COTS light sources and detectors. We also consider the effects of environmental noise such as background solar radiation, which typically limits performance of these systems
192 citations
18 Sep 2005
TL;DR: In this paper, the authors present a preliminary design for an optical modem system based on an omnidirectional source and receiver, which is capable of sending back high-quality video or other high-rate sensor data.
Abstract: Regional cabled observatories will bring broadband Internet to the seafloor around areas that include hydrothermal vent sites and other scientifically interesting features. The ideal platform for exploring these sites in response to episodic events is a remotely-piloted, autonomous underwater vehicle (AUV) that is capable of sending back high-quality video or other high-rate sensor data. The combined requirement of remote command/control and high data rates argues for a bi-directional optical communications link capable of streaming data at 1-10 Mbit per second rates. In this paper, we present a preliminary design for an optical modem system based on an omnidirectional source and receiver. The functional requirements and system constraints driven by use case scenarios are first reviewed. This is followed by a discussion of the optical transmission properties of seawater and the resulting impact on detection in high-rate communications, including coding considerations. A link budget and the data rate versus range relationship are developed. Validation results in a test tank and in the ocean will then be reviewed.
176 citations