Underwater optical wireless communication network

The growing need for underwater observation and subsea monitoring systems have stimulated considerable interest in advancing the technologies of underwater wireless communication. This communication technology is expected to play an important role in investigating climate change, monitoring biogeochemical, ecological and biological change in the ocean and lake environments, which helps to control and maintain oil production facilities and harbors using unmanned underwater vehicles (UUVs), ships, buoys, and submarines. However, the present technology of underwater acoustic communication cannot provide the high data rate required to investigate and monitor these environmental factors. To overcome this problem, Optical wireless communication has been proposed as the best alternative to meet this challenge. In this paper, optical communication using LEDs is presented as an advancement over acoustic modems for scenarios where high speed but only limited access applications is required and also lower power, less complex communication systems are desired. On the basis of Beer-Lambert's law it was deduced that blue light (470 nm) of the visible spectrum suffered the least attenuation underwater. We attempt to design an ultra-bright blue LED based transmitter system by optimizing it with opto-coupler and an enhanced photodiode based receiver system are developed with the goal of transmitting data at higher rates by using On-Off keying technology. The objective was to transmit the data at a rate of at least 1 Mbps over a distance of 30 meters. Here, real time data could be sent or received with the help of simulation results.

The Earth is a water planet, two-thirds of which is covered by water. With the rapid developments in technology, underwater communications has become a fast growing field, with broad applications in commercial and military water based systems. The need for underwater wireless communications exists in applications such as remote control in the off-shore oil industry, pollution monitoring in environmental systems, collection of scientific data from ocean-bottom stations, disaster detection and early warning, national security and defense (intrusion detection and underwater surveillance), as well as new resource discovery. Thus, the research of new underwater wireless communication techniques has played the most important role in the exploration of oceans and other aquatic environments. In contrast with terrestrial wireless radio communications, the communication channels in underwater wireless networks can be seriously affected by the marine environment, by noise, and by limited bandwidth and power resources, and by the harsh underwater ambient conditions. Hence, the underwater communication channel often exhibits severe attenuation, multipath effect, frequency dispersion, and constrained bandwidth and power resources, etc., which turn the underwater communication channel into one of the most complex and harsh wireless channels in nature. When facing these unique conditions in diverse underwater applications, many new challenges, which were not encountered in terrestrial wireless communications, are emerging in underwater acoustic, optical, and RF communications for future underwater wireless networks. Of these challenges, acoustic and optical are the most compelling, and somewhat complementary, owing to the potential for longer range and high bandwidth networked communications in sizeand power-constrained modems and unmanned systems.

Guest Editorial

In scientific, military, and industrial sectors, the development of robust and efficient submarine wireless communication links is of enormous interest. Underwater wireless communications can be carried out through acoustic, radio frequency (RF), and optical waves. Underwater optical communication is not a new idea, but it has recently been considered because seawater exhibits a window of reduced absorption both in the visible spectrum and long-wavelength UV light (UV-A). Compared to its bandwidth limited acoustic counterpart, underwater optical wireless communications (UOWCs) can support higher data rates at low latency levels. Underwater wireless communication networks are important in ocean exploration, military tactical operations, environmental and water pollution monitoring. Anyway, given the rapid development of UOWC technology, documents are still needed showing the state of the art and the progress made by the most current research. This paper aims to examine current technologies, and those potentially available soon, for Underwater Optical Wireless Communication and to propose a new perspective using UV-A radiation.

Optical communication has been employed in a wide range of applications, including terrestrial, submarine, inter-satellite, and even space communication. It is particularly successful in fiber-based communication networks that vastly reshape modern life through the Internet. With the intensified activities such as undersea resource exploration, ecosystem monitoring, and recreation, underwater is an exciting new arena for optical wireless communication (OWC). In this paper, we review the recent progress of underwater and water-air OWC systems. Channel characterization, communication system design, and performance investigations are given. Critical limitations and effective mitigation methods to overcome the influence of bubbles and waves are presented. We also address the current issues for proper performance comparison under different wave conditions. With further research in channel modeling, device innovation, and system design optimization, practical and robust underwater and water-air OWC systems can be realized.

The Earth is a water planet, two-thirds of which is covered by water. With the rapid developments in technology, underwater wireless communications and networks have become a fast growing field, with broad applications in commercial and military waterbased systems. The need for underwater wireless communications exists in applications such as remote control in the off-shore oil industry, pollution monitoring in environmental systems, collection of scientific data from ocean-bottom stations, disaster detection and early warning, national security and defense (intrusion detection and underwater surveillance), as well as new resource discovery. Thus, the research into new underwater wireless communication techniques has played the most important role in the exploration of oceans and other aquatic environments. In contrast to terrestrial wireless radio communications, the underwater channel poses serious technical challenges depending on the communications modalities (e.g., acoustic, optical, or RF/magnetic) employed. These include, but are not limited to, ambient channel noise, severe attenuation, propagation delay, multipath, frequency dispersion, bio-fouling, lack of access to precise time synchronization (GPS), and constrained bandwidth and power resources. These challenges also provide an opportunity for design of hybrid and adaptive transmission, such as the underwater acoustic and optical communications and networks, which have somewhat complementary properties, with potential for longer range and higher bandwidth networked communications in size- and power-constrained modems and mobile unmanned systems.

Although many researchers have achieved wireless optical ranging and communication based on Avalanche Photon Diode (APD) detectors and PIN detectors. However, due to the low sensitivity of APD and PIN detectors, their working distances are limited. In order to achieve long-distance underwater wireless optical communication, a Single-Photon Avalanche Diode (SPAD) with photon-limited sensitivity is used to detect optical signals. In addition, most literatures do not specially design the data frames of ranging and communication, which makes it difficult to perform ranging and communication at the same time. In view of the fact that there is currently no systematic solution for simultaneous communication and high-precision ranging under underwater photon counting, this paper sorts out the relevant technical details, proposes an integrated ranging and communication scheme applied to photon counting, designs a special data frame that integrates ranging and communication, and proposes an extraction and recovery scheme for ranging and communication signals. Simulation shows that this scheme can achieve underwater photon counting wireless optical communication with a communication distance of 160m and an SER of 9.75×10-6, and the ranging accuracy is better than 1.59cm.

In traditional underwater communication systems, acoustic waves are commonly used. However, acoustic underwater systems have low bandwidth, which is not enough for modern wireless sensors and underwater vehicles. The use of radio waves also does not provide the desired combination of transmission speed and range. All this has led to the development of optical wireless underwater communication, as it potentially provides a higher data rate than traditional acoustic underwater communication systems with significantly lower energy consumption. One of the main difficulties in designing underwater optical wireless systems is the complexity of modeling the physical and chemical characteristics of ocean water. The purpose of this survey is to generalize the available models of underwater optical communication links taking into account the various propagation effects that affect the range and speed of the system.

There is a speedy development withinside the place of broadband wi-fi communications as the global call for in elevating for large bandwidth and extra mobility. The speedy increase withinside the previous few a long time withinside the WAN's and LAN's is particularly because of growing improvement in excessive potential and occasional loss optical fiber. But, the main downside in optical fiber cable communique is that optical fiber receives broken in a long-haul installation. Thus, underwater communication has paved the way for overcoming this disadvantagefor programs of underwater statement and sea monitoring, the importance of underwater wi-fi optical communication has expanded. Attenuation and fading of light propagation, as well as impairment in the performance of underwater wireless optical communications, are caused by elements such as underwater absorption, scattering, and turbulence (UWOC). UWOC is a short-range wireless communication system that allows for greater data throughput than classic acoustic communication systems while using less power and posing fewer computing problems. The main challenge for underwater wireless communication, on the other hand, is from the fundamental properties of ocean or sea water. Understanding the feasibility and minimising the BER, as well as boosting the reliability of high data rate underwater communication lines, is the main topic of this paper. This study's purpose is to conduct underwater optical communication research while also producing new ideas to aid in the development of future underwater communication systems.

Bit error rate performance of underwater optical wireless communication test bed simulating the seawater conditions

Underwater wireless optical communication (UWOC) has emerged as a key technology for next-generation underwater wireless data transmission. Semantic communication is regarded as a promising communication paradigm to improve the efficiency and robustness of UWOC systems. However, existing underwater wireless optical semantic communication (UWOSC) system lacks the capability to adapt the code rate to different channel states, leading to intelligence inadequacy and coding inefficiency. In this paper, we introduce environment semantics into the UWOSC system for the first time, and propose an environment semantics aided underwater wireless optical semantic communication (ESA-UWOSC) framework. Based on this framework, we develop a system leveraging computer vision and deep learning for adaptive rate transmission. The ESA-UWOSC system is realized by a channel state perception mechanism (CSPM) for extracting environment semantics from the channel environment image to obtain the channel gain, a link network (LinkNet) for enabling variable code rate transmission of source semantic information, and a prediction network (PreNet) for predicting the optimal code length that satisfies the transmission task requirement. The combined operation of these three modules enables the ESA-UWOSC system to actively perceive channel state and perform adaptive rate transmission accordingly. In a series of experiments conducted on an emulated UWOC experimental platform, the results show that the ESA-UWOSC system outperforms the baseline scheme, achieving superior performance with lower bandwidth consumption, especially in harsh channel environments. Moreover, the results also demonstrate that the ESA-UWOSC system can achieve adaptive rate transmission based on the perceived channel state to meet transmission task requirement.

A routing-benefited deployment algorithm combining static and dynamic layouts is proposed, and its comprehensive performance evaluation is given in this article. The proposed routing-benefited deployment algorithm is intended to provide a suitable network deployment and subsequent data transmission approach for underwater optical networking and communication. Static nodes are anchored for long-term monitoring, and movable nodes can adjust their depths based on the virtual force and move with the variation of area-of-interest changing. Then, nodes begin to collect data that they can monitor and transmit to sink nodes. Here, the underwater wireless optical communication model is described to actualize the real environment, and the vector-based forwarding protocol is particularly considered to compare the impact of different deployment algorithms on routing. It is shown by simulation experiment results that routing-benefited deployment algorithm outperforms several existing traditional virtual force deployment algorithms in terms of coverage, lifetime, energy consumption balance, packet-loss rate, and time-delay.

We conducted full-duplex class 1 eye-safe transmission experiments, including 4K video demonstrating robust connectivity to maximize transmission capacity under optimal paths by introducing aerial relay nodes within underwater optical wireless communication networks in shallow seas.

SummaryThe emergence of 5G and 6G technologies has resulted in a faster, more automated, and more intelligent data flow in the digital world. A wide spectrum of optical wireless communication is made available to support 5G and 6G technologies, and it can meet the demands of high‐speed optical wireless communication. Trade‐offs involving latency, power consumption, deployment costs, and hardware/computational overhead have always been a part of 5G/6G technologies. The decline in the trade‐offs indicated above has major implications for networking capacity. The proposed work modulated a new grid‐based communication protocol (GCP) with elephant swarm optimization (ESO) to surpass those issues with optical wireless communication devices. This protocol employs an integrated strategy to split the network and choose the cluster head effectively. Different GCP‐ESO‐related algorithms have been explored. Various components of the OSNs, including network energy usage, cluster, and non‐cluster header nodes, are also calculated using mathematical analysis. The results have been simulated using MATLAB software. The simulation precisely demonstrates that the proposed GCP‐ESO outperforms the emerging MCH‐EOR and RDSAOA‐EECP methods concerning energy consumption (0.46 J), packet loss ratio (PLR) (0.60%), end‐to‐end latency (11.0 s), packet delivery rate (PDR) (99.41%), routing (0.112), the lifetime of the network (3718 s), and throughput (0.989 Mbps).

<div><p class="Affiliation">The demand for underwater communication is growing at a faster pace since few decades. Maximizing the communication performance and building efficient network architecture for underwater communication is a challenging task. Due to the reduced bandwidth, high error rate, noise, propagation delay, water currents and increased cost in the network topology, the existing communication techniques are not feasible for underwater communication. Research in high speed underwater transmission technology has become a primary need in today’s world. By using underwater acoustic sensor network high transmission distance can be achieved but with lower data rates, high power consumption, larger delays and with higher cost. Underwater Optical Communication can be used to increase data rates and lower delays but it suffers from high attenuation due to which it cannot be used for data transfer over larger distances. Research in the area of hybrid sensor networks is a challenging task and has many open research challenges, which needs to be solved. In this paper we discuss the various architectures of underwater communication. A comparative study is made on different routing protocols and localization algorithms. The challenges faced by acoustic and optical communication are also discussed.</p></div>