scholarly journals Effect of Link Misalignment in the Optical-Internet of Underwater Things

Electronics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 646 ◽  
Author(s):  
Ruhul Amin Khalil ◽  
Mohammad Inayatullah Babar ◽  
Nasir Saeed ◽  
Tariqullah Jan ◽  
Ho-Shin Cho
Keyword(s):  
Optical Communication ◽  
High Speed ◽  
Data Communication ◽  
Divergence Angle ◽  
Optical Internet ◽  
Wireless Optical Communication ◽  
Transmission Distance ◽  
Received Power ◽  
Lateral Offset ◽  
Marine Applications

Underwater wireless optical communication (UWOC) enables high-speed links in water for the optical Internet of Underwater Things (O-IoUT) networks. O-IoUT provides various marine applications, including ocean exploration, environmental monitoring, and underwater navigation. O-IoUT typically utilizes light-emitting diodes (LEDs) and different laser diodes (LDs) such as green/blue lasers to achieve efficient data communication in the underwater environment. The high-speed optical communication is limited up to a few tens of meters due to underwater channel impairments and misalignment between the transmitter (Tx) and the receiver (Rx). UWOC provides high-speed communications only in the line of sight conditions, and a small misalignment between the Tx and the Rx can degrade the system performance. In an attempt to understand and minimize this misalignment issue, we investigate how received power in a UWOC system depends on the transmitted beam’s divergence angle. Simulation results are provided to show the effectiveness of the study by comparing the plane, Gaussian, and spherical beams. Monte Carlo simulations are utilized to determine the maximum allowable lateral offset between Tx and Rx for a given Tx divergence angle. The results provide an overview and design-based trade-off between different parameters such as lateral offset, the power received, and bandwidth of the channel. The proposed method improves not only the maximum allowed link-span but also the bandwidth of the channel for a given transmission distance.

scholarly journals Performance Evaluation of Underwater Wireless Optical Communication System by Varying the Environmental Parameters

Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 74
Author(s):  
Dong-Chang Li ◽  
Chia-Chun Chen ◽  
Shien-Kuei Liaw ◽  
Shofuro Afifah ◽  
Jiun-Yu Sung ◽  
...  
Keyword(s):  
Optical Communication ◽  
Environmental Parameters ◽  
Artificial Seawater ◽  
Blue Laser ◽  
Laser Source ◽  
Water Tank ◽  
Wireless Optical Communication ◽  
Transmission Distance ◽  
Flow Turbulence ◽  
The Impact

Underwater wireless optical communication (UWOC) has been considered a promising technology for high-speed underwater transmission. Some Gb/s level UWOC systems applying visible light have been demonstrated with a transmission distance of several meters or more. Many of the previous works focus on the advanced technologies to push the systems’ capacity–distance performance. However, practical environmental factors issue such as flow turbulence and temperature variation are seldom studied through specific statistical/theoretical models. In this paper, a UWOC system using a 450 nm blue light laser source was set up using a 1.5-m water tank with mirrors located on both sides for single or multiple reflections corresponding to different transmission distances. The blue laser was modulated by a 1.25 Gbps NRZ-OOK format with PRBS of 7, 24 or 31, respectively, for system performance comparison. The bit error rate (BER) values were measured in 1.5, 3.0 and 6 m, respectively, for system evaluation. At room temperature, the BER value was down to 10 × 10−8 for a 1.25 Gbps data rate in a 6 m transmission. Then, the UWOC transmission system experiment was carried out under several environmental parameters such as temperature, turbulence, artificial seawater by adding salt to simulate practical application in river or sea. When a submerged motor with an output of 1200 L/h was used as a water flow turbulence source, the impact to BER and transmission quality was negligible. For the temperature change issue, the experiment shows that around the original temperature of 25 °C had the best BER as compared to other temperature ranges from 10 to 50 °C. For artificial seawater issues by adding salt to simulate the real seawater environment. The transmission distance was only 3-m instead of 6 m, mainly due to particle scattering and water disturbance. With the motor pump on, the power penalty was 1 dB at 10 × 10−8 BER when compared to the motor pump off.

scholarly journals A New Modified MPPM for High-Speed Wireless Optical Communication Systems

ETRI Journal ◽  
2013 ◽  
Vol 35 (2) ◽  
pp. 188-192 ◽  
Author(s):  
Mehdi Rouissat ◽  
Riad A. Borsali ◽  
Mohammad E. Chikh-Bled
Keyword(s):  
Optical Communication ◽  
Communication Systems ◽  
High Speed ◽  
Wireless Optical Communication ◽  
Optical Communication Systems

Optical Communication

2011 ◽  
pp. 290-315
Author(s):  
Otto Strobel ◽  
Daniel Seibl ◽  
Jan Lubkoll
Keyword(s):  
Optical Communication ◽  
Communication Systems ◽  
High Speed ◽  
Fiber Optic ◽  
Glass Fibers ◽  
Data Communication ◽  
Visible Light Communication ◽  
Physical Layers ◽  
Optical Communication Systems ◽  
Polymer Optical Fibers

The idea of this chapter is to give an overview on optical communication systems. The most important devices for fiber-optic transmission systems are presented, and their properties discussed. In particular, we consider such systems working with those basic components which are necessary to explain the principle of operation. Among them is the optical transmitter, consisting of a light source, typically a low speed LED or a high speed driven laser diode. Furthermore, the optical receiver has to be mentioned; it consists of a photodiode and a low noise, high bit rate, front-end amplifier. Yet, in the focus of the considerations, you will find the optical fiber as the dominant element in optical communication systems. Different fiber types are presented, and their properties explained. The joint action of these three basic components can lead to fiber-optic systems, mainly applied to data communication. The systems can operate as transmission links with bit rates up to 40 Gbit/s. But communication systems are also used for recent application areas in the MBit/s region, e.g. in aviation, automobile, and maritime industry. Therefore—besides pure glass fibers—polymer optical fibers (POF) and polymer-cladded silica (PCS) fibers have to be taken into account. Moreover, even different physical layers like optical wireless and visible light communication can be a solution.

scholarly journals An Experimental Assessment of LiFi Data Communication

2020 ◽  
Vol 61 (1) ◽  
pp. 73-87
Author(s):  
V. Gordon ◽  
P. Danquah
Keyword(s):  
Real Time ◽  
Optical Communication ◽  
Angular Position ◽  
Data Communication ◽  
Physical Layer ◽  
Data Rate ◽  
The Internet ◽  
Experimental Assessment ◽  
Wireless Optical Communication ◽  
Lateral Distance

In this paper, two functional light fidelity real-time testbeds implemented on custom Light fidelity (LiFi) kits are presented. This paper evaluates the use of LiFi technology over differ­ent distances and angular placement of illuminating devices and endpoint transceivers with connectivity locally and to the internet. The objective is to determine if distance or angular positioning in LiFi influence speeds or not. Finally, it aims to contribute to knowledge in the LiFi communication domain. We were limited to developing a customized testbed for wireless optical communication by accessing data in the physical layer via photons. In a lateral dis­tance and angular position, we examined the performance of a laptop with LiFi activated by a 3730 lm LED. The setup evaluated the performance of our design in a downlink and uplink scenario where the transmitter was embedded in the main LED unit and the laptop was used as a photoreceiver. The data rate/kbps, the lateral distance / m, and the angle displacement / θ° were the comparison metrics. The results of the tests show that the transmission of LiFi is not influenced by distance and angular positioning for both downloads and uploads over different distances.

scholarly journals Non-line-of-sight methodology for high-speed wireless optical communication in highly turbid water

2020 ◽  
Vol 461 ◽  
pp. 125264 ◽  
Author(s):  
Xiaobin Sun ◽  
Meiwei Kong ◽  
Omar Alkhazragi ◽  
Chao Shen ◽  
Ee-Ning Ooi ◽  
...  
Keyword(s):  
Optical Communication ◽  
High Speed ◽  
Line Of Sight ◽  
Turbid Water ◽  
Wireless Optical Communication ◽  
Non Line Of Sight
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