Abstract

Free-space optical (FSO) communication is a vital solution to meet the growing demand for high-bandwidth satellite-to-ground communication, offering advantages such as higher data rates and security compared to traditional RF systems. However, its performance is significantly affected by meteorological conditions, particularly cloud formations (e.g., cirrus, cumulus, and stratocumulus) and atmospheric turbulence, which cause signal attenuation, scattering, and phase distortions. Addressing these challenges through better understanding and mitigation strategies is essential to ensure reliable and efficient performance of FSO systems under various atmospheric conditions.
In this study, we evaluated the performance of ground-to-satellite FSO systems under varying atmospheric turbulence and cloud conditions using the OptiSystem simulator. We analyze multiple modulation techniques, including Quadrature Phase Shift Keying (QPSK), 8-Phase Shift Keying (8PSK), 16PSK, and 16-Quadrature Amplitude Modulation (16QAM), to assess their resilience based on link range, bit error rate (BER), quality factor, optical signal-to-noise ratio (OSNR), and error vector magnitude (EVM). The results demonstrate that QPSK outperforms higher-order modulation schemes in high-attenuation environments, maintaining the lowest BER and highest quality factor, making it the most suitable choice for FSO communication in satellite networks. These findings provide critical insights into the optimization of modulation strategies for robust and reliable ground-to-satellite optical links.

Key words: Atmospheric turbulence, cloud attenuation, FSO, Gamma-Gamma turbulence model, modulation techniques, Optical ground-to-satellite link.