Article

Prediction of drop size distribution parameters for optical wireless communications through moderate continental fog

International Journal of Satellite Communications and Networking (Impact Factor: 0.74). 01/2011; 29:97-116. DOI: 10.1002/sat.950
Source: DBLP

ABSTRACT

Wireless optical communication links (OCL), or free space optics links involving optical ground stations are highly influenced by the earth atmosphere due to the interaction of the optical wave with particles of different size and shape. Fog, clouds, rain and snow cause significant signal attenuation, thus limiting the performance of OCL. In this paper, we consider the behavior of OCL in the troposphere under moderate continental fog conditions, which are important for both ground–ground and ground–space OCL. The impact of the droplet size distribution (DSD) of fog is investigated, by processing laser attenuation measurements carried out in Milan (Italy) and Graz (Austria). Significant differences are observed between measured and predicted attenuation when using standard values for the DSD parameters. Hence, new sets of DSD parameters are proposed to model peak, mean and median values of measured attenuation for moderate continental fog. These, in turn, can be useful to make accurate link availability predictions, thus improving the quality of service design for OCL. Copyright © 2010 John Wiley & Sons, Ltd.

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Available from: László Csurgai-Horváth
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    • "Fog is characterized by several physical parameters such as liquid water content, particle size distribution, temperature and humidity. Since the size of fog particles is comparable to the transmission wavelength of optical and near infrared waves, Mie scattering applies and results in high attenuation [13]. Fog comprises of fine water droplets, ice crystals or smoke particles suspended in the atmosphere. "
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    • "Fog, having very low densities, contains very small amount of water and thus results in lower values of LWC around 0.05 g/m 3 for a moderate fog (visibility range around 300 m). Much higher values of LWC (around 0.5 g/m 3 ) usually mean formation of thick or dense fog (visibility range of about 50 m) [20]. Similarly, clouds may have LWC value of 0.06405 g/m 3 and 1-3 g/m 3 for Cirrus and Cumulonimbus clouds, respectively measured in the same amount of space [22]. "
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