Characterization of UAV-Based Free-Space Optical (FSO) Channel Under Real Atmospheric Conditions in the Tropical Savanna Region of Korhogo, Northern Côte d'Ivoire

Wongnigué Allassane Soro^1, , Amadou Soumahoro¹, Douatia Koné^{1, 2} and Aladji Kamagaté¹

¹Mathematics Physics Chemistry, LaTIATE Laboratory, Université Peleforo Gon Coulibaly, Korhogo, Côte d’Ivoire

²Research and Technological Innovation Department, Ecole Supérieure Africaine des Technologies de l’Information et de la Communication, Abidjan, Côte d’Ivoire

Cite this paper:
Wongnigué Allassane Soro, Amadou Soumahoro, Douatia Koné and Aladji Kamagaté. Characterization of UAV-Based Free-Space Optical (FSO) Channel Under Real Atmospheric Conditions in the Tropical Savanna Region of Korhogo, Northern Côte d'Ivoire. International Journal of Physics. 2026; 14(2):36-47. doi: 10.12691/ijp-14-2-3

Abstract

Unmanned aerial vehicle (UAV)-assisted free-space optical (FSO) communication is a promising solution for rapidly deployable, high-capacity wireless networks. However, realistic channel characterization in tropical environments remains challenging because atmospheric attenuation, turbulence, pointing errors, and angle-of-arrival (AoA) fluctuations are often investigated independently and rarely using long-term site-specific meteorological data. This paper presents a unified statistical framework for modeling a UAV-assisted FSO link under the tropical savanna climate of Korhogo, northern Côte d’Ivoire. The proposed model jointly incorporates weather-dependent attenuation caused by rain, fog, humidity, and dust, Málaga-distributed atmospheric turbulence, pointing errors, and AoA fluctuations within a heterodyne-detection decode-and-forward relay architecture. Atmospheric attenuation parameters are derived from six years (2020–2025) of meteorological observations collected by the Korhogo station of the National Meteorological Agency (ANAM), enabling realistic channel characterization. Closed-form channel statistics are employed to evaluate the signal-to-noise ratio (SNR) and bit-error rate (BER). The results show seasonal atmospheric attenuation ranging from 0.81 dB/km during the dry season to 3.10 dB/km under severe rainy conditions. Increasing the UAV altitude from 200 m to 500 m extends the communication range from 2.5 km to 4.5 km for an SNR threshold of 10 dB, while the reliable transmission distance at a BER of 10⁻³ increases from 2.5 km to 3.2 km. More importantly, the analysis reveals a distance-dependent altitude trade-off. Beyond approximately 5 km, humidity-induced attenuation and beam divergence outweigh turbulence mitigation, challenging the common assumption that higher UAV altitudes always improve FSO performance. These findings provide practical design guidelines for deploying reliable UAV-assisted FSO systems in tropical environments.

Keywords:
Angle-of-Arrival fluctuations Atmospheric attenuation Atmospheric turbulence Channel characterization Málaga distribution Pointing errors UAV-FSO communications

This work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

References:

[1]	Aboelala, O., Lee, I. E., and Chung, G. C. (2022). “A Survey of Hybrid Free Space Optics (FSO) Communication Networks to Achieve 5G Connectivity for Backhauling,” Entropy, vol. 24, no. 11, p. 1573.
[2]	Mohsan,S. A. H., Khan,M. A., and Amjad,H. (2023). “Hybrid FSO/RF networks: A review of practical constraints, applications and challenges,” Opt. Switch. Netw., vol. 47, p. 100697.
[3]	Gupta,A., Dhawan, D., and Gupta, N. (2023). “Review on UAV-based FSO links: recent advances, challenges, and performance metrics,” Opt. Eng., vol. 63, no. 04.
[4]	Wang,J. Y., Ma,Y., Lu, R. R., Wang,J. B., Lin,M., and Cheng, J. (2021). “Hovering UAV-Based FSO Communications: Channel Modelling, Performance Analysis, and Parameter Optimization,” IEEE J. Sel. Areas Commun., vol. 39, no. 10, pp. 2946–2959.
[5]	Singh,D., and Swaminathan,R. (2022). “Comprehensive Performance Analysis of Hovering UAV-Based FSO Communication System,” IEEE Photonics J., vol. 14, no. 5, pp. 1–13.
[6]	Badarneh,O. S., El Bouanani,F., Almehmadi,F. S., and Silva,H. S. (2023). “FSO Communications Over Doubly Inverted Gamma-Gamma Turbulence Channels With Nonzero-Boresight Pointing Errors,” IEEE Wirel. Commun. Lett., vol. 12, no. 10, pp. 1761–1765.
[7]	Duyen,T. H. (2023). “Performance Analysis of FSO DF Relays with Log-Normal Fading Channel,” J. Opt. Commun., vol. 44, no. 3, pp. 395–403.
[8]	Xu,G., Yu,X., Wang,J., Song,Z., and Zhang,Q. (2024). “Performance Analysis of Multi-UAV Optical Communication Systems Over Foggy Channel Under Málaga Turbulence and Pointing Error Impairments,” IEEE Photonics J., vol. 16, no. 6, pp. 1–16.
[9]	Kone,D.,SORO,P. A., and Kamagaté,A. (2024) “Evaluation of Free Space Optical (FSO) Link Under Weather Conditions in Abidjan,” Int. J. Phys., vol. 12, no. 6, pp. 247–259.
[10]	Salih,M. G. M., Al-Dharrab,S. I., Alawsh,S. A., and Muqaibel,A. H. (2024). “Performance Analysis of Multi-Hop UAVs Using FSO Communications Under Humidity and Sandstorms Conditions,” IEEE Open J. Commun. Soc., vol. 5, pp. 6987–7001.
[11]	Shen,B., Chen,J., Xu,G., Chen,Q., and Wang,J. (2023). “Performance Analysis of a Drone-Assisted FSO Communication System over Málaga Turbulence under AoA Fluctuations,” Drones, vol. 7, no. 6, p. 374.
[12]	Moon,H.J., Chae,C.B., Wong,K.K., and Alouini,M.S. (2025). “A Generalized Pointing Error Model for FSO Links With Fixed-Wing UAVs for 6G: Analysis and Trajectory Optimization,” IEEE Trans. Wirel. Commun., vol. 24, no. 7, pp. 5723–5737.
[13]	INS, “Résultats globaux définitifs RGPH 2021,” Institut National de la Statistique (INS). Accessed: May 05, 2026. [Online]. Available: https://rp2021.anstat.ci/.
[14]	Kottek,M., Grieser,J., Beck,C., Rudolf,B., and Rubel,F. (2006). “World Map of the Köppen-Geiger climate classification updated,” Meteorol. Zeitschrift, vol. 15, no. 3, pp. 259–263.
[15]	Silué, S., Kouassi, A. A., Dago, D. N., Dajuma, A., Doumbia, M., Touré, D. E., Kéita, S. (2021). “Assessing seasonal climate variability impact on the malaria patient’s cases in the north of Côte d’Ivoire,” Adv. Image Video Process., vol. 9, no. 6.
[16]	Jérôme,A.N. (2022). “Kafoudal,” Rev. des Sci. Soc. l’université Peleforo Gon Coulibaly korhogo, vol. 3–4, p. 316.
[17]	Elamassie,M. and Uysal,M. (2023). “Free Space Optical Communication: An Enabling Backhaul Technology for 6G Non-Terrestrial Networks,” Photonics, vol. 10, no. 11, p. 1210.
[18]	Kim,I. I., and Korevaar,E. J., “Availability of free-space optics (FSO) and hybrid FSO/RF systems,” E. J. Korevaar, Ed., Nov. 2001, p. 84.
[19]	Kaushal, H. and Kaddoum,G. (2017). “Optical Communication in Space: Challenges and Mitigation Techniques,” IEEE Commun. Surv. Tutorials, vol. 19, no. 1, pp. 57–96.
[20]	Yao, C., Kacou, M., Koffi, E. S, Dao, A., Dutremble, C., Guilliod, M., Kamagaté, B., Perrin, J-L., Salles, C., Neppel, L., Paturel, J-E., Zahiri, E. P., Séguis, L. (2024). “Rainfall risk over the city of Abidjan (Côte d’Ivoire): first contribution of the joint analysis of daily rainfall from a historical record and a recent network of rain gauges,” Proc. IAHS, vol. 385, pp. 259–265.
[21]	Ghoname,S., Fayed,H. A., El Aziz,A. A., and Aly,M. H. (2017). “FSO System Performance Enhancement: Receiver Impact,” J. Adv. Res. Appl. Mech., vol. 37, no. 1, pp. 1–8.
[22]	Elamassie,M. and Uysal,M. (2022). “Aerosol Attenuation Model for High Altitude UAV-Based FSO Links,” in 2022 13th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP), IEEE, Jul. 2022, pp. 71–75.
[23]	Ajam,H., Najafi, M., Jamali,V., and Schober,R. (2020). “Ergodic Sum Rate Analysis of UAV-Based Relay Networks With Mixed RF-FSO Channels,” IEEE Open J. Commun. Soc., vol. 1, pp. 164–178.
[24]	Chapala,V. K. and Zafaruddin,S. M. (2022). “Unified Performance Analysis of Reconfigurable Intelligent Surface Empowered Free-Space Optical Communications,” IEEE Trans. Commun., vol. 70, no. 4, pp. 2575–2592.
[25]	Ai,D. H., Trung,H. D., and Tuan,D. T. (2020). “On the ASER performance of amplify-and-forward relaying MIMO/FSO systems using SC-QAM signals over log-normal and gamma-gamma atmospheric turbulence channels and pointing error impairments,” J. Inf. Telecommun., vol. 4, no. 3, pp. 267–281.
[26]	Trung,H. (2021). “Performance of UAV-to-Ground FSO Communications with APD and Pointing Errors,” Appl. Syst. Innov., vol. 4, no. 3, p. 65.
[27]	Ansari,I. S., Yilmaz,F., and Alouini,M.-S. (2016). “Performance Analysis of Free-Space Optical Links Over Málaga ($\mathcal{M} $) Turbulence Channels With Pointing Errors,” IEEE Trans. Wirel. Commun., vol. 15, no. 1, pp. 91–102, Jan. 2016.
[28]	Alheadary,W. G., Park,K.H., and Alouini,M.S. (2017). “Performance analysis of multihop heterodyne free-space optical communication over general Malaga turbulence channels with pointing error,” Optik (Stuttg)., vol. 151, pp. 34–47.
[29]	ANAM, “Historique des prévisions météo à Korhogo.” Accessed: May 10, 2026. [Online]. Available: https://www.historique-meteo.net/afrique/cote-d-ivoire/korhogo/2026/.
[30]	Gnamien, S., Yoboué, V., Liousse, C., Ossohou, M., Keita, S., Bahino, J., Siélé, S., Diaby, L. (2021). “Particulate Pollution in Korhogo and Abidjan (Cote d’Ivoire) during the Dry Season,” Aerosol Air Qual. Res., vol. 21, no. 1, p. 200201.
[31]	Xu,M., Xu,G., Dong,Y., Wang,W., Zhang,Q., and Song,Z. (2023). “UAV-assisted FSO communication system with amplify-and-forward protocol under AOA fluctuations: A performance analysis,” China Commun., vol. 20, no. 11, pp. 111–130.
[32]	Ahmed,H. Y., Zeghid,M., Khan,A. N., and Abd El-Mottaleb, S. A. (2025). “Fuzzy Logic-Based Performance Enhancement of FSO Systems Under Adverse Weather Conditions,” Photonics, vol. 12, no. 5, p. 495.
[33]	Bayraktar,M., Garces, S.L. M., Duncan,J. C. M., and Chatzinotas,S., “Rytov Variance of Adaptive Optics Applied Modified Von-Karman Spectrum,” in 2024 IEEE Wireless Communications and Networking Conference (WCNC), IEEE,pp. 1–5.
[34]	Gao,W., Han,C., and Chen,Z. (2023). “Scintillation and Attenuation Modelling of Atmospheric Turbulence for Terahertz UAV Channels,” arXiv Prepr. arXiv2305.08820.
[35]	Moon,H.J., Chae,C.B., Wong,K.K., and Alouini,M.S. (2025). “A Generalized Pointing Error Model for FSO Links With Fixed-Wing UAVs for 6G: Analysis and Trajectory Optimization,” IEEE Trans. Wirel. Commun., vol. 24, no. 7, pp. 5723–5737.