Enhancing the Atmospheric Visibility and Fog Attenuation Using a Controlled FSO Channel

Ijaz, Muhammad; Ghassemlooy, Zabih; Pérez, Joaquín; Brazda, Vladimir; Fišer, Ondřej

doi:10.1109/lpt.2013.2264046

Cited by 56 publications

(29 citation statements)

References 13 publications

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“…These results suggest that the sole dependency of the visibility as in eq. (3) is insufficient and the Ws, T and RH are also seen to exhibit statistical significance and they interwoven with the dependence in atmospheric attenuation effects [13]. Figure 7(a) indicates that the relationship of RH to attenuation as in eq.…”

Section: Data For 6 June 2013-monsoonmentioning

confidence: 94%

“…The fundamental law to estimate attenuation of optical signal on the basis of the atmospheric visibility (V) in km is Koschmieder law, which defines the visibility as the distance to an object/optical intensity at which the visual contrast/transmittance of an optical signal drops to certain value of the visual/transmittance threshold T th of the original visual contrast/intensity (100%) along the propagation path [11][12][13][14]. The meteorological visibility can be therefore expressed with the Beer-Lambert law as [15,16] V ¼ 10log 10 T th ð Þ β λ ¼ 4:343 log 10 T th ð ÞR log 10 …”

Section: Introductionmentioning

confidence: 99%

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Comparison of Different Models for Ground-Level Atmospheric Attenuation Prediction with New Models According to Local Weather Data for FSO Applications

Raj¹,

Selvi²

2015

Journal of Optical Communications

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A dedicated Free Space Optical Link (FSOL) for the range of 0.5 km at an altitude of 15.25 m is established and explained. The power levels of the received signal with meteorological parameters are continuously measured using the opto-electronic assembly and developed weather station respectively and stored in a computer. The existing models selected for comparative analysis are briefed. Measured meteorological parameters and optical attenuation of size [2000 Â 4] are used for linear regression analysis as well as to design the mathematical models more suitable at the test field. In addition, the prediction accuracy of the proposed and selected models during different seasons in one-year period are investigated and validated in terms of RMSE. The average Root Mean Square Error (RMSE) of 0.041 dB/km for the optical attenuation is achieved in the longer range dynamic of meteorological parameters during different local seasons.

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Section: Data For 6 June 2013-monsoonmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Comparison of Different Models for Ground-Level Atmospheric Attenuation Prediction with New Models According to Local Weather Data for FSO Applications

Raj¹,

Selvi²

2015

Journal of Optical Communications

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“…A box of turbulence simulator (BTS) acts as an atmospheric chamber, as shown in Figure 4 [18,19], that provides turbulent media for optical propagation in the FSO. The BTS has dimensions of 4.0 m×0.5 m×0.5 m and operates by mixing flows of a highto-cold temperature-gradient.…”

Section: Methodsmentioning

confidence: 99%

Optical Spatial Filter to Suppress Beam Wander and Spatial Noise Induced by Atmospheric Turbulence in Free-Space Optical Communications

Darusalam

Priambodo

Rahardjo

2015

Advances in Optical Technologies

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We propose an optical spatial filter (OSF) method to suppress beam wander and spatial noise effects. Signal from random displacements of the focus spot around the optical axis within the constricted area is collected. This method advantageously suppresses fluctuations in signal intensity. The OSF consists of a pinhole and cone reflector. The pinhole produces Fresnel diffraction on the focus spot. The cone reflector provides directed reflectance onto the pinhole for random focus spot displacements due to beam wander. The calculations of signal power are based on fluctuations of signal intensity that are minimized by the circular aperture function of the pinhole and the cosine of the reflectance angle from the cone reflector. The method is applied to free-space optical communications at a wavelength of 1.55 m with an atmospheric chamber to provide optical propagation media. Based on calculations, the beam wander angles that can be received by the OSF are from 14.0 ∘ to 28.0 ∘ . Moreover, based on experiment, the OSF with a pinhole diameter of 20.0 m and cone reflector diameter of 1.5 mm produces signal power of −15.3 dBm. Both calculations and experiment show that the OSF enhances the received signal power in the presence of turbulence.

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“…λ is the wavelength of the laser being used and β λ denotes the loss coefficient. Based on the Kim model, q is defined as [31]…”

Section: Fog/smoke Attenuationmentioning

confidence: 99%

Differential Signalling in Free-Space Optical Communication Systems

et al. 2018

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In this paper, we review the differential signalling techniques and investigate its implementation of in free-space optical (FSO) communication systems. The paper is an extended version of our previous works, where the effects of background noise, weak turbulence and pointing errors (PE) were investigated separately. Here, for the first time, we present a thorough description of the differential signalling scheme including for combined effects. At first, we present an extension of the analysis of differential signalling to the case of moderate to strong atmospheric turbulence. Next, we investigate a more general case where both channel turbulence and PE are taken into consideration. We provide closed-form expressions for the optimal detection threshold and the average bit-error-rate, and present a set of numerical results to illustrate the performance improvement offered by the proposed differential signalling under various turbulence and PE conditions. differential signaling to mitigate pointing errors effect in an FSO communication link. One of the authors, M.M.A. was supported by the PhD studentship from Northumbria University. The work was also supported by the The European project H2020 MSC ITN no. 764461 (VISION) and CTU project SGS17/182/OHK3/3T/13. Conflicts of Interest:The authors declare no conflict of interest. Author Contributions: M.M.A. and M.R.B. carried out the mathematical analysis and simulation; Z.G. and S.Z. proofread and confiremed the analysis; M.-A.K. and M.P.J.L. contributed to the theory material.Acknowledgments: Portions of this work were presented at the IEEE International Conference on Communications ICC in 2016 (ICC2016), using differential signaling to mitigate pointing errors effect in an FSO communication link. One of the authors, M.M.A. was supported by the PhD studentship from Northumbria University. The work was also supported by the The European project H2020 MSC ITN no. 764461 (VISION) and CTU project SGS17/182/OHK3/3T/13. Conflicts of Interest:The authors declare no conflict of interest.

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Enhancing the Atmospheric Visibility and Fog Attenuation Using a Controlled FSO Channel

Cited by 56 publications

References 13 publications

Comparison of Different Models for Ground-Level Atmospheric Attenuation Prediction with New Models According to Local Weather Data for FSO Applications

Comparison of Different Models for Ground-Level Atmospheric Attenuation Prediction with New Models According to Local Weather Data for FSO Applications

Optical Spatial Filter to Suppress Beam Wander and Spatial Noise Induced by Atmospheric Turbulence in Free-Space Optical Communications

Differential Signalling in Free-Space Optical Communication Systems

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