Underwater Wireless Communication System Research Articles

ОРГАНИЗАЦИЯ ПОДВОДНОЙ БЕСПРОВОДНОЙ СИСТЕМЫ СВЯЗИ

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.

BECS-II: an updated bio-inspired electrocommunication system for small underwater robots.

Some weakly electric fish can use electric signals to interact and communicate with each other in dark and complex underwater environments where traditional underwater communication fails. In our previous work, we developed a bio-inspired electrocommunication system (BECS) that serves as an effective alternative to traditional methods in this challenging underwater scenario performing communication at a speed of approximately 1200 bps (bits per second) within approximately 3 m. In this study, a novel underwater wireless communication system (BECS-II) is proposed to upgrade the BECS with much better performance. We first propose theoretical and simulation models for electrocommunication, including the effects of the angular frequency and electrode impedance. A custom-made digital communication system is employed in BECS-II to improve the anti-interference ability and channel capacity of the BECS. In addition, a novel circuit optimization strategy was used to develop a customized circuit to enhance the transmitting and receiving capabilities of the BECS-II. Dual-frequency communication is proposed to meet the communication demands of different tasks by taking inspiration from the task allocation and evolution mechanisms of weakly electric fish. The experimental results showed that BECS-II outperformed BECS in high-frequency mode at both the communication speed (approximately 20 kbps) and distance (approximately 10 m), whereas in low-frequency mode, it extended the communication range by transmitting data up to a distance of approximately 20 m at a speed of approximately 200 bps. A substantial increase in the communication distance can expand the robot motion space in a group and improve group flexibility.&#xD.

Underwater Wireless Video Communication Using Blue Light

Interest in wireless blue light communication is increasing because this technology shows promise for realizing high-speed, long-distance and full-duplex underwater communication. Here, we demonstrate an underwater wireless communication system, OceanLink, to establish full-duplex data transmission using blue light. Both the transmitter and receiver are housed together to independently transmit and receive data simultaneously. To obtain a longer transmission distance and better light field distribution, the transmitter is composed of an array of three light-emitting diode (LED) units with the dominant emission peak wavelength centered around 452 nm, each of which merges four LEDs in series. These LEDs are synchronously driven via a main processing unit to pulse blue light using a nonreturn-to-zero on-off keying modulation scheme. At the receiver, light passes through a neutral density (ND) filter and a focus lens to hit the transducer, which converts light signals into electrical signals. The waterproof OceanLink achieves a bidirectional communication rate of 4 Mbps with a wireless transmission distance of 12 m in a swimming pool, wherein the ND factor is 256 and the nephelometric turbidity unit is 1.7. Thus, real-time full-duplex underwater video communication is experimentally demonstrated.

Energy harvesting techniques for sustainable underwater wireless communication networks: A review

The emergence of various underwater wireless communication systems has been on the rise due to increasing human activities in the marine environment. In underwater wireless communication networks (UWCNs), several communication devices, such as sensors and autonomous underwater vehicles (AUV) are interconnected to expand communication coverage, monitoring, information gathering, and surveillance. These devices operate on batteries, making their replacement and recharging difficult. Consequently, sustaining the operational lifetime of UWCNs is deemed a major challenge. This leads to the development of various energy harvesting (EH) techniques to perpetuate the power supply to underwater devices. In this paper, we present a review of various energy sources and EH techniques applicable to UWCNs. To achieve this, we classify the energy sources into various categories in order to establish the peculiarities of each source and the type of harvester applicable to each category. Based on this classification, we present discussions on various contributions of articles related to applications of EH techniques in UWCNs. In addition to various insights gained from the presented papers, we establish that energy harvesters based on triboelectric effect, piezoelectric effect, sediment microbial fuel cell, acoustic, and optical power transfer are suitable for low-power (milliwatt-order) consuming devices such as sensors. Also, for devices with high power consumption requirement, such as AUV, solar and inductive power transfer-based harvesters should be employed. Furthermore, we identify several technical challenges that should be taken into consideration during the planning and system design phases. Finally, we highlight open research areas that could further improve the EH and communication processes in UWCNs.

Research on duplex underwater wireless laser communication system

To improve the bit error rate (BER) of underwater wireless laser communication and increase communication speed, a duplex underwater wireless laser communication system is designed. The system uses both blue and green lasers to transmit signals simultaneously, and adopts an improved modulation and demodulation algorithm to achieve separate modulation of the two sets of signals. A duplex underwater wireless laser communication system builds based on 440 and 550 nm lasers. On the basis of analyzing the absorption and scattering characteristics of seawater in laser communication, the influence of turbulence on communication efficiency is discussed. Improved the traditional duplex modulation algorithm and conducted communication testing at a depth of 2.0 m underwater. The experimental results show that when the communication distance increases from 5 to 50 m, the BER of the unoptimized duplex mode increases from 2.34 × 10−7 to 3.5 × 10−5. After adopting the optimization algorithm, the BER increases from 2.81 × 10−7 to 1.18 × 10−6, and the signal attenuation has been significantly suppressed. The duplex communication structure and algorithm can effectively reduce the impact of communication distance on bit BER.

Analysis and Simulation of BER Performance of Chaotic Underwater Wireless Optical Communication Systems

It is shown that modulation methods based on the phenomenon of dynamic chaos and correlation processing can improve the noise immunity of underwater wireless communication systems. This provides the possibility of signal recovery at negative values of the signal-to-noise

UQRCom

While communication in the air has been a norm with the pervasiveness of WiFi and LTE infrastructure, underwater communication still faces a lot of challenges. Even nowadays, the main communication method for divers in underwater environment is hand gesture. There are multiple issues associated with gesture-based communication including limited amount of information and ambiguity. On the other hand, traditional RF-based wireless communication technologies which have achieved great success in the air can hardly work in underwater environment due to the extremely severe attenuation. In this paper, we propose UQRCom, an underwater wireless communication system designed for divers. We design a UQR code which stems from QR code and address the unique challenges in underwater environment such as color cast, contrast reduction and light interfere. With both real-world experiments and simulation, we show that the proposed system can achieve robust real-time communication in underwater environment. For UQR codes with a size of 19.8 cm x 19.8 cm, the communication distance can be 11.2 m and the achieved data rate (6.9 kbps ~ 13.6 kbps) is high enough for voice communication between divers.

Acoustic Wave Propagation Patterns in the Ocean Column

Temperature and salinity play a role in the speed of sound and the process of sound propagation of acoustic waves in the water. Research on the propagation of sound waves in the ocean is a very interesting topic to do because it has many applications, including in underwater wireless communication systems and maritime security. This study aimed to analyze the propagation of acoustic waves in different water depths. The modeling was carried out with flat wave characteristics, in which the bathymetry characteristics of the seawater were ignored. In this ray path simulation, the frequency of 5.3Hz was used at 3 stations with different seawater depths in the Makassar Strait using temperature and salinity data downloaded from marine.coperniccus.eu data. The movement pattern of the acoustic waves was simulated using the Bellhop method. The ray tracing simulation results showed significant differences at the three locations. This was influenced by several factors, including the condition of the seawater environment, the placement of the transducer, the speed of sound, and the depth. Shallow seawater would show a more complicated ray path than deep seawater. The greater the angle of the half beam used, the greater the distance of the range of each beam of light will be so that the reflection of the resulting beam of light covers each column of seawater. The closer the distance between the resulting ray paths, the smaller the energy lost.

Efficient Equalization and Carrier Frequency Offset Compensation for Underwater Wireless Communication Systems

Efficient Equalization and Carrier Frequency Offset Compensation for Underwater Wireless Communication Systems

Net 5.75 Gbps/2 m Single-Pixel Blue Mini-LED Based Underwater Wireless Communication System Enabled by Partial Pre-Emphasis and Nonlinear Pre-Distortion

Blue LEDs are cost-effective optical sources suitable for underwater optical wireless communication (UOWC) systems. However, the nonlinearity and the low-pass response of LEDs alongside the limited sensitivity of photodetectors constrain the capacity and reach of UOWC systems. Here we address these issues by means of a combined DSP scheme consisting of partial pre-emphasis and nonlinear pre-distortion. Partial pre-emphasis pre-compensates for the low-pass response of the system while relaxing the power reduction induced by a high peak-to-average power ratio, whereas nonlinear pre-distortion can effectively alleviate the LED nonlinearity with only marginal impact on the signal power. Further, it is found that the signal power and the signal SNR at the receiver can be improved by setting a low current bias for the mini-LED because of less saturated radiative recombination. The effectiveness of this combined DSP scheme and device conditioning approach is experimentally validated and enables the transmission of a net 5.75 Gb/s PAM-8 signal over 2 m of distance underwater, which, to our knowledge, is the highest net data rate achieved for single-pixel LED-based UOWC systems.

Full Duplex Physical and MAC Layer-Based Underwater Wireless Communication Systems and Protocols: Opportunities, Challenges, and Future Directions

Underwater wireless communication has gained a great deal of attention in the last couple of decades because of its applications in the military, industrial, and monitoring sectors. Despite the extreme physical and MAC layer difficulties, acoustics are used for various applications among the various modes of underwater communication technologies used. While significant research efforts have been made to address these issues, the bottleneck remains in achieving high bandwidth, high throughputs, and data rate. Researchers have begun to look into full duplex (FD) implementation to improve bandwidth efficiency and increase data rate and throughput. Users can send and receive data simultaneously over the FD links, maximizing bandwidth utilization and increasing throughput. As a result, we thoroughly reviewed various FD physical layered UWAC systems and MAC layered protocols for underwater communication. The various problems that the aforementioned systems and protocols have faced, as well as the solutions suggested in previous works to solve each problem, are also highlighted. Various metrics are used to compare the performance of various physical layered FD systems and FD MAC protocols. We also explore some of the open research questions in these FD-physical layered and MAC layered protocols, as well as future research directions. Based on ample information, we suggest a cross-layered architecture based on various IBFD-SI cancellations, DA-CSMA, and FD-MAC protocols. This review provides a broad view of the current FD physical and MAC layered protocols based on acoustic communication, as well as recommendations.

Değişik Ortam Ve Sistem Parametreleri İçin Sualtı Kablosuz Optik Haberleşme Monte Carlo Kanal Kapasitesinin İncelenmesi

Increasing interest in oceans increases the scientific, commercial and military studies in this field, in which underwater wireless communication systems are frequently used. In literature, underwater wireless, synchronous, high speed data transfer can only be done with optical systems. The distorting effects of underwater environment (UE) on optical waves significantly affect the communication distance and speed of underwater wireless optical communication (UWOC) systems. Therefore, in order to design reliable UWOC systems, it is important to examine effects of various UEs on UWOC systems on a realistic channel model. In this study, instead of the approximate channel models, Monte Carlo approach UWOC channel model, which is accepted in literature with its high accuracy and sensitivity, was used, and effects of the transmitter's beam divergence angle and aperture diameter of receiver parameters, which are important design parameters for UWOC systems, on a typical UWOC system were investigated. In this study, three various UEs, namely clean ocean, coastal ocean and harbor waters, which are frequently used as benchmarks in the literature, were taken into consideration, and channel impulse responses, signal to noise ratios and channel capacity distributions were presented and interpreted for each UE. With the results obtained, the communication speed and distance limits of a typical UWOC system were determined, and a prediction was provided for UWOC systems that can be used in various UEs and parameter values.

An Automated Underwater Wireless Communication System Using Li-Fi with IOT Support and GPS Positioning

The most difficult medium for data communication is the underwater medium. It is due to its characteristics. The various existing mode of the communication in water medium are electromagnetic waves, acoustic waves and optical signal. But all these have its own drawbacks. The loss will be huge for Electro-Magnetic (EM) waves, so it is limited to the short range communication, optical waves has line of sight issues. To overcome these, in this paper, a Li-Fi technique is used for data transmission in water medium. It uses Light Emitting Diode (LED) sources for transmission of data. This will ensure the maximum transmission rate and it is more efficient and cheaper than the other existing methods. In this paper, automation via Bluetooth, IoT and it has GPS tracking capabilities are also incorporated.

Design and deployment of IoT based underwater wireless communication system using electronic sensors and materials

Underwater wireless communication performs a critical role in tactical surveillance, water pollution control, oil exploration and maintenance, offshore mining, local weather control and oceanography research. It is an excellent operation for the military, industry, and scientific community. To facilitate these applications, wide variety of unmanned motors or units, which require excessive bandwidth and excessive ability to switch data are deployed underwater. Even though some of these goals have been achieved by underwater acoustic communication discipline but constrained by bandwidth. These factors have led to the advent of underwater Wi-Fi connectivity (UWC), which provides higher bandwidth than the usual acoustic contact systems with substantially reduced energy consumption and simplified technological problems for short-range Wi-Fi connexions. This paper under water wireless communication is achieved by using Internet of Things (IoT) an advanced technology along with microcontroller and Wi-Fi. In this study temperature, turbidity and distance between the objects are measured with the respective sensors connected to the transmitter and recorded at the receiver side by using IoT technology for different time intervals. It is concluded that the proposed UWC system based on IoT can be low cost, efficient and can be used for different applications related to underwater.

Propagation characteristics of the perfect vortex beam in anisotropic oceanic turbulence.

The propagation model of orbital angular momentum (OAM) modes carried by the perfect vortex (pv) beam through anisotropic oceanic turbulence links is established and the factors influencing the OAM propagation are discussed. The findings show that the self-focusing property of pv beams is beneficial to the propagation of OAM modes: a smaller topological charge, a smaller initial radius, and an optimized half-ring width can alleviate degrading effects of turbulence on the pv beam. Additionally, the pv beam with a longer wavelength is more resistant to turbulent interference. The oceanic conditions with a higher dissipation rate of kinetic energy per unit mass of seawater, larger values of anisotropy and inner-scale factor, a smaller temperature-salinity contribution ratio, or a lower mean-squared temperature dissipation rate can improve the signal mode detection probability. The results are expected to further optimize the design of OAM-based underwater wireless communication systems.

Design and analysis of an optical camera communication system for underwater applications

The growing interest in underwater explorations has stimulated considerable interest in advancing the enabling technologies of underwater wireless communication (UWC) systems. The study presents the design and implementation techniques of a short-range unidirectional UWC system which uses optical camera communication (OCC) principles. OCC systems have light emitting diodes at the transmitter, with the receiver being a camera. Overall system design considerations, synchronisation and frame selection, and a novel spatial position-based image processing algorithm to decode data from frames are discussed. Also, the optimisation techniques used in the image processing algorithm are also elaborated. Importance of few of key features of an OCC system, namely camera quality, transmission distance and the threshold value used for image binarisation are demonstrated through numerical results using simulations via synthetically generated images. Further, the bit error rate (BER) performance of the system is evaluated using the experimental proof of concept setup in clear water, muddy water and under turbulence conditions. Overall BER performance in the order of 10 -3 within the communication distance of 1 m is observed, and it shows that the proposed system design and algorithms can be used to realise an UWC link for short-range applications successfully.

A novel cooperative spectrum signal detection algorithm for underwater communication system

In order to further improve the spectrum resource detection probability and increase the spectrum utilization rate in underwater wireless communication systems, this paper designs a novel multi-layer cooperative spectrum sensing algorithm based on compressed sensing, which uses compressed sensing technology to estimate the spectrum to reduce the sampling rate and the overhead of sonar signals. This new algorithm seeks the optimal hyper-parameter through Bayesian model. The multi-layer Bayesian model is introduced into the Dirichlet process to realize the automatic grouping of compressed perceptual data with the information from the non-parametric grouping mechanism, and the optimal super-parameters are selected through the fusion center to determine the spectrum. Simulation results show that the proposed algorithm fully considers the temporal correlation of compressed perceptual data and effectively improves spectral sensing performance of underwater communication system.

Underwater laser communication with sloped pulse modulation in turbid water

In this article, we propose the demonstration of an underwater wireless laser communication link operating at data rates of up to 100 Mbps over a band-limited turbid water channel using a modified pulse position modulation scheme with a sloped pulse. The communication link uses an avalanche photodiode module as the receiver. The bit error rate of a 5.4 × 10−6 by 450-nm blue laser diode in turbid water with 1.4 Nephelometric Turbidity Unit was below the forward error correction limit. Our demonstrated underwater wireless laser communication system is simple to use and maintains a high data transmission rate.

Experimental Evaluation of OFDM-Based Underwater Visible Light Communication System

High-speed, reliable, flexible, and cost-effective underwater wireless communication systems have a wide variety of use in scientific, civilian, and commercial domains. Visible light communication (VLC) seems to be a promising candidate in satisfying majority of the requirements listed above. From this perspective, VLC could easily be deployed in heterogeneous wireless networking scenarios with high quality of service. Therefore, in this paper, an adapted LTE frame structure is implemented for underwater VLC (UVLC) system. The performance of UVLC system employing asymmetrically clipped optical orthogonal frequency division multiplexing modulation technique is practically tested by taking channel estimation and synchronization into account. Also, the effects of varying orthogonal frequency division multiplexing parameters on the system's signal-to-noise ratio and the bit-error-rate (BER) performances are studied. The implementation is tested for quadrature phase shift keying and 16-quadrature amplitude modulation techniques supporting both 128- and 1024-points fast Fourier transform configurations, which correspond to data rates of 1.92 and 15.36 Mbps, respectively. Experimental results show that BER could be reduced down to a level on the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> .

Zero‐padding block transmission for underwater optical wireless communications

An underwater optical wireless communication (UOWC) system is considered. For such system, a zero-padding (ZP) block-transmission scheme is presented to reduce the influence of inter-symbol-interference. Simulation results, which are based on the existing experimental data of channel pulse response, show that ZP system is effective especially for serious dispersive channel with high data rates and thus, potentially applicable to the high data rate UOWC systems.