scholarly journals Effects of Multipath Attenuation in the Optical Communication-Based Internet of Underwater Things

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6201
Author(s):  
Rabia Qadar ◽  
Waleed Bin Qaim ◽  
Jari Nurmi ◽  
Bo Tan
Keyword(s):  
Multiple Scattering ◽  
Optical Communication ◽  
Limited Range ◽  
Optical Signal ◽  
Optical Channel ◽  
Response Analysis ◽  
Temporal Response ◽  
Magnitude Response ◽  
Optical Source ◽  
Temporal Dispersion

The propagation of light underwater is tied closely to the optical properties of water. In particular, the underwater channel imposes attenuation on the optical signal in the form of scattering, absorption, and turbulence. These attenuation factors can lead to severe spatial and temporal dispersion, which restricts communication to a limited range and bandwidth. In this paper, we propose a statistical model to estimate the probability density function of the temporal dispersion in underwater wireless optical communication (UWOC) based Internet of Underwater Things (IoUTs) using discrete histograms. The underwater optical channel is modeled using Monte Carlo simulations, and the effects of temporal dispersion are presented by measuring the magnitude response of the channel in terms of received power. The temporal response analysis is followed by an extensive performance evaluation in terms of bit error rate (BER). To facilitate in-depth theoretical analysis, we have measured and presented magnitude response and BER of the channel under different field-of-views (FoVs), apertures, and water types. The three main areas under study are (i) BER versus link distance behavior, (ii) temporal response of the channel, and (iii) effect of scattering on photon travel. Our study shows the two main factors that contribute to beam spreading and temporal dispersion are (i) diffusivity of the optical source and (ii) multiple scattering. Furthermore, our results suggest that temporal dispersion caused due to multiple scattering cannot be mitigated completely; however, it can be minimized by optimizing the receiver aperture.

Comparative analysis of SISO and wavelength diversity-based FSO systems at different transmitter power levels

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Varun Srivastava ◽  
Abhilash Mandloi ◽  
Dhiraj Kumar Patel
Keyword(s):  
Optical Signal ◽  
Free Space Optical ◽  
Optical Source ◽  
Transmit Power ◽  
Single Input Single Output ◽  
Transmitter Power ◽  
Single Output ◽  
Communication Links ◽  
Single Input ◽  
Matching Performance

AbstractFree space optical (FSO) communication refers to a line of sight technology, which comprises optical source and detector to create a link without the use of physical connections. Similar to other wireless communication links, these are severely affected by losses that emerged due to atmospheric turbulence and lead to deteriorated intensity of the optical signal at the receiver. This impairment can be compensated easily by enhancing the transmitter power. However, increasing the transmitter power has some limitations as per radiation regulations. The requirement of high transmit power can be reduced by employing diversity methods. This paper presents, a wavelength-based diversity method with equal gain combining receiver, an effective technique to provide matching performance to single input single output at a comparatively low transmit power.

scholarly journals A 45 nm CMOS Avalanche Photodiode with 8.4-GHz Bandwidth

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 65
Author(s):  
Wenhao Zhi ◽  
Qingxiao Quan ◽  
Pingping Yu ◽  
Yanfeng Jiang
Keyword(s):  
Optical Communication ◽  
Integrated Circuit ◽  
Communication Systems ◽  
Complementary Metal Oxide Semiconductor ◽  
Avalanche Photodiode ◽  
Cmos Technology ◽  
Optical Signal ◽  
Oxide Semiconductor ◽  
Monolithically Integrated ◽  
Process Modification

Photodiode is one of the key components in optoelectronic technology, which is used to convert optical signal into electrical ones in modern communication systems. In this paper, an avalanche photodiode (APD) is designed and fulfilled, which is compatible with Taiwan Semiconductor Manufacturing Company (TSMC) 45-nm standard complementary metal–oxide–semiconductor (CMOS) technology without any process modification. The APD based on 45 nm process is beneficial to realize a smaller and more complex monolithically integrated optoelectronic chip. The fabricated CMOS APD operates at 850 nm wavelength optical communication. Its bandwidth can be as high as 8.4 GHz with 0.56 A/W responsivity at reverse bias of 20.8 V. Its active area is designed to be 20 × 20 μm2. The Simulation Program with Integrated Circuit Emphasis (SPICE) model of the APD is also proposed and verified. The key parameters are extracted based on its electrical, optical and frequency responses by parameter fitting. The device has wide potential application for optical communication systems.

Effect of Crosstalk in Super Dense Wavelength Division Multiplexing System using Hybrid Optical Amplifier

2019 ◽  
Vol 40 (4) ◽  
pp. 347-351
Author(s):  
Chakresh Kumar ◽  
Rakesh Goyal
Keyword(s):  
Wavelength Division Multiplexing ◽  
Optical Communication ◽  
Power Level ◽  
Optical Amplifier ◽  
Optical Signal ◽  
Dense Wavelength Division Multiplexing ◽  
Channel Spacing ◽  
Wavelength Division ◽  
Fiber Nonlinearity ◽  
Hybrid Optical Amplifier

Abstract Analysis of proposed 400×10 Gbps super dense wavelength division multiplexing (SD-WDM) system has been evaluated in term of crosstalk and optical signal to crosstalk ratio (OSCR). Amplification is carried out using RAMAN-EDFA hybrid optical amplifier (HOA) for the transmission of 300 km. The pump power of 550 mW at 1520 nm and 580 mW at 1530 nm are set to RAMAN and EDFA optical amplifier respectively. Further, the power level of 0 dBm with channel spacing of 100 GHz has shown the remarkable outcome of controlling the fiber nonlinearity to maintain the best rating optical communication for long haul distance.

scholarly journals Comparison of DPSK and RZ-DPSK Modulations in Optical Channel with Speed of 10 Gbps

2017 ◽  
Vol 41 (2) ◽  
pp. 185-196 ◽  
Author(s):  
Petr Ivaniga ◽  
Tomáš Ivaniga
Keyword(s):  
Phase Shift ◽  
Optical Communication ◽  
Error Rate ◽  
High Speed ◽  
Optical Network ◽  
Optical Channel ◽  
Q Factor ◽  
Differential Phase Shift ◽  
Differential Phase ◽  
Optic Waveguide

<div>This article is devoted to the problematic of error rate and modulations in optical communication. Optic waveguide shows insufficiencies in high speed transfers manifested by corrupted transfer. Although modern technological processes contributed to lowering these insufficiencies, it would be uneconomical to completely reconstruct the optical network infrastructure. The solution is only partial so we approach more economical methods, such as modulations. The article works with a 10 Gbps channel with two modulation types, namely DPSK (Differential Phase Shift Keyed) and RZ-DPSK (Return to Zero-Differential Phase Shift Keyed). These modulations are evaluated and compared according to BER (Bit Error Rate) and Q-factor.<div> </div></div>

scholarly journals Seasonal Temperature Dependence of Availability of Under-Water Visible Optical Communications through Egypt Nile River Water

2021 ◽  
Author(s):  
Seif eldin A. Zaghloul ◽  
Bedir Yousif ◽  
Walid S. El-Deeb
Keyword(s):  
Temperature Dependence ◽  
Water Temperature ◽  
Optical Communication ◽  
Optical Communications ◽  
Pure Water ◽  
Optical Power ◽  
Optical Channel ◽  
Nile River ◽  
Transmitted Power ◽  
Ray Trace

Abstract Underwater visible optical communications become very important for their high velocity and more data rate. But the optical is suffering from the high water attenuation. For optical communication. Pure water is the best of the ten water types with wavelengths λ = 455 and 486 mm. The Nile river water is a pure water without salinity (fresh water). The temperature of the water is daily changes and so the performance of optical communication underwater becomes temperature-dependent. A simplified expression very good accuracy of Egypt Nile water to determine the water refractive index, water dispersion, water attenuation, received optical power, and SNR as direct temperature dependence is done. The optical channel loss model is used to determine the received optical power and the ray trace model is used to define optical radiation pattern. The equation of optical received power by ray trace is the same as that by using the optical channel loss model except for the transmitter gain of them are different. For λ = 486nm with water temperature varying from 4oC to 30oC, the corresponding refractive index decreases from 1.3399 to 1.3379 (so, the optical velocity under fresh water increases from 2.239*108m/s to 2.2423*108 m/s), dispersion decreases from 0.6492 to 0.6459 (ps/m nm), attenuation factor decreases from 0.0378 m− 1 to 0.0345m− 1 and so the required transmitted optical power due to attenuation for 800 m long shrinks to 7.4 %. The Effect of temperature becomes more evident with more link distance. The required transmitted power to achieve the required SNR increases with the more data rate. To overcome the unavailability of the link due to water temperature, the transmitted power must be controlled by the daily water temperature. In this study, the temperature dependence of the performance of the optical link and a simulation proposed example design is done.

ROF systems performance efficiency based on continuous phase frequency shift keying phase modulation scheme

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mahmoud M. A. Eid ◽  
Vishal Sorathiya ◽  
Sunil Lavadiya ◽  
Ismail A. Abd El-Aziz ◽  
Sayed Asaduzzaman ◽  
...  
Keyword(s):  
Communication Network ◽  
Frequency Shift ◽  
Optical Communication ◽  
Phase Modulation ◽  
Noise Figure ◽  
Continuous Phase ◽  
Optical Channel ◽  
Modulation Scheme ◽  
Frequency Shift Keying ◽  
Shift Keying

Abstract Radio over fiber (ROF) technique has been presented with hybrid ordinary modulation technology to achieve improvement in optical communication network performance. Fiber Bragg grating (FBG) is employed in single mode (SM) optical channel in order to enhance the transmission environment with dispersion compensation. The continuous phase frequency shift keying phase modulation (CPFSKPM) technique is included in this study. Both previous and proposed models have been inspected and investigated. Min. bit error rate (BER), max. Q factor, signal/noise ratio (SNR), received power (RP), and noise figure (NF) are the most essential parameters able to explain the behavior performance of optical communication network model.

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