Performance of free-space optical communication systems: effect of aerosol-induced lower atmospheric warming

Abstract

We report the effect of aerosol-induced local atmospheric heating and the resulting changes in the lower atmospheric optical turbulence on the performance of Free-Space Optical (FSO) communication links. A closed form mathematical expression is derived to estimate the influence of aerosol-induced warming on the Bit Error Rate (BER) of a Binary Phase Shift Keying FSO communication link through Gamma-Gamma modeled turbulence. Our results demonstrate a strong impact, with the aerosol-induced turbulence taking a toll on the signal-to-noise ratio of ~20 dB for a BER of 10 −9 . Aerosol-induced warming produces significant variations in BER compared to the clear atmospheric conditions and can subdue the benefits of improved beam alignment. IntroductionFree Space Optical (FSO) communication is a line of sight technology, where data laden optical signals propagate through the atmosphere characterized by fluctuations in the thermodynamical properties such as temperature, pressure and wind velocity and direction etc., superposed on the regular variations [1]. These random fluctuations cause wave-front distortion and signal degradation at the receiver. Continuously varying nature of the signalboth temporally and spatially -makes the retrieval of information more difficult. Wave front distortion of laser beam propagating through the atmosphere has been studied extensively and reported to have limiting effects on the performance of communication systems [2][3][4][5]. Such distortions arise due to the interaction of the wave front with (a) thermal eddies and (b) gas molecules and suspended particles (aerosols) in the atmosphere. Random fluctuations in the intensity of a beam propagating through the atmospheric turbulence are quantified by the refractive index structure parameter (C n 2 ). Several models are in use to estimate clear air optical turbulence [6]. Recent studies on the modulation of C n 2 due to variations in the atmospheric residence time and vertical distribution of aerosols [7,8] have clearly quantified the aerosol-induced optical scintillations through absorption, scattering and radiative effects, when they are present close to the surface or in the elevated layers [9] of the Earth's lower atmosphere (troposphere). Extinction effects of aerosols on optical turbulence [10][11][12] and FSO communication links [5,13,14] were reported earlier. Commonly used intensity fluctuation models [6] neglect the heating effects of absorbing atmospheric aerosols (such as black carbon and dust, which strongly absorb in the visible through near infra-red wavelengths of the incident solar energy). Hence, the modulation of atmospheric C n 2 by aerosol-induced warming and its consequence on FSO communication systems have not been investigated extensively. Under this backdrop, the present work focuses on the radiative

The BER of the New FSO Receiver Manufactured by RTCVD and Solar Cell Technology

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Free space optics communication system design using iterative optimization

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Bit Error Rate Performance in CDMA Free Space Optical Links with SIK Receiver under Fog Conditions

“…Being an attractive and economical choice, the Free-Space Optical (FSO) communication presents a substitute for conventional Optical Fiber Communication (OFC), particularly in situations where deploying fiber optic infrastructure is economically and logistically challenging (Singh et al, 2021). However, the effectiveness of FSO techniques can be compromised by various weather-centric elements, such as turbulence, pointing inaccuracies, haze, fog, clouds, rain, and snow, leading to performance degradation (Mahalati, 2012;Yang, 2014;Esmail et al, 2019;Sunilkumar et al, 2019;Ashrafzadeh et al, 2020). Accurately comprehending the influence of these atmospheric conditions on the propagation of optical signals through the atmosphere remains a significant quandary for the research community.…”