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Proceedings Paper

Scintillation loss in free-space optic IM/DD systems
Author(s): Florian David
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Paper Abstract

When designing free-space optics systems, one key issue is to assess the impact of scintillations and to find an appropriate link margin to cope with atmospheric fading. Huge effort is spent to find mathematical models to describe laser beam propagation through the atmosphere. However, these models are quite cumbersome to use for the communications engineer. On the other hand, there are empirical models that try to describe the influence of scintillations and other system parameters in a simple and easy to use manner. Nevertheless, they are empirical and not based on theory. This paper is intended to close the gap between mathematical theory and empirical models. Therefore, a simple yet accurate receiver model is introduced. Based on turbulence theory and using the recently proposed convolution method assuming independent sub-aperture intensities, probability distributions of the received power are derived. Aperture averaging as well as multiple transmitter systems can be described this way. Power penalties are found by numerically calculating the resulting bit error probabilities for varying mean values of received power. Finally a model for appropriate link margins under different atmospheric conditions, taking transmitter diversity and aperture averaging into account, is derived and compared to empirical models.

Paper Details

Date Published: 16 June 2004
PDF: 11 pages
Proc. SPIE 5338, Free-Space Laser Communication Technologies XVI, (16 June 2004); doi: 10.1117/12.528832
Show Author Affiliations
Florian David, DLR (Germany)

Published in SPIE Proceedings Vol. 5338:
Free-Space Laser Communication Technologies XVI
Steve Mecherle; Cynthia Y. Young; John S. Stryjewski, Editor(s)

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