Abstract
Free space optics (FSO) technology is gaining attention for 6G and beyond networks due to its ability to provide secure data transmission, operate without the need for licensed spectrum, and support significantly higher data rates. Although the FSO system has various advantages, long-distance communication transmissions are inadequate. The dependability of FSO technology is predominantly influenced by various weather factors. This paper’s results seek to enhance the efficiency of FSO technology for long-distance communication. The present work utilised a combined methodology that mixes multi-beam combinations and self-homodyne direct-detection (SHDD) approaches inside a wavelength division multiplexed (WDM) FSO technology. The system is assessed through several implementations of single beam (SB), 4 multiple beams (MB4), and 8 multiple beams (MB8). This paper utilises the gamma–gamma (GG) channel model. The findings show that MB provided the best performance throughout a range of 1.6–12 km, with all lengths depending on the surrounding conditions. The link quality is determined by calculating the bit error rate (BER), Q factor and Eye height.
-
Research ethics: No human or animal subjects were involved in this research.
-
Informed consent: The work described has not been published previously, is not under consideration for publication elsewhere, and its publication is approved by all authors. The manuscript will not be published elsewhere in any form without the written consent of the Publisher.
-
Author contributions: Y.K.G.: conceptualisation, study design, and manuscript preparation. A.G.: supervision, conceptualisation, and study design.
-
Use of Large Language Models, AI and Machine Learning Tools: Large Language Models were used solely for language editing. All authors reviewed and approved the final manuscript.
-
Conflicts of interest: The authors declare no conflict of interest.
-
Research funding: None.
-
Data availability: Data will be made available on request.
References
1. Malik, A, Singh, P. Free space optics: current applications and future challenges. Int J Optoelectron 2015;2015. https://doi.org/10.1155/2015/945483.Search in Google Scholar
2. Singh, H, Miglani, R, Mittal, N, Gupta, S, Tubbal, F, Raad, R, et al.. Designing an optimized free space optical (FSO) link for terrestrial commercial applications under turbulent channel conditions. Opt Quant Electron 2023;55:532. https://doi.org/10.1007/s11082-023-04805-w.Search in Google Scholar
3. Singh, M, Atieh, A, Grover, A, Barukab, O. Performance analysis of 40 Gb/s free space optics transmission based on orbital angular momentum multiplexed beams. Alex Eng J 2022;61:5203–12. https://doi.org/10.1016/j.aej.2021.10.043.Search in Google Scholar
4. El-Nayal, MK, Aly, MM, Fayed, HA, AbdelRassoul, RA. Adaptive free space optic system based on visibility detector to overcome atmospheric attenuation. Results Phys 2019;14:102392. https://doi.org/10.1016/j.rinp.2019.102392.Search in Google Scholar
5. Singh, H, Mittal, N, Miglani, R, Singh, H, Gaba, GS, Hedabou, M. Design and analysis of high-speed free space optical (FSO) communication system for supporting fifth generation (5G) data services in diverse geographical locations of India. IEEE Photon J 2021;13:1–12. https://doi.org/10.1109/JPHOT.2021.3113650.Search in Google Scholar
6. Grover, M, Singh, P, Kaur, P. Mitigation of scintillation effects in WDM FSO system using multibeam technique. J Telecommun Inf Technol 2017;2017:69–74. https://doi.org/10.26636/jtit.2017.111917.Search in Google Scholar
7. Elsayed, EE. Performance enhancement in FSO relay systems with MISO via multi - Hop M - Ary PPM integrating and spatial modulation over gamma – gamma channels. J Opt 2025;54:3364–79. https://doi.org/10.1007/s12596-024-01936-5.Search in Google Scholar
8. Elsayed, EE. Performance analysis and modeling: atmospheric turbulence and crosstalk of WDM – FSO network. J Opt 2024. https://doi.org/10.1007/s12596-024-02434-4.Search in Google Scholar
9. Parikh, J, Jain, VK. Study on statistical models of atmospheric channel for FSO communication link. In: Proc. Int. Conf. Eng. (NUiCONE) Nirma Univ. Ahmedabad, India: IEEE; 2011:1–7 pp.10.1109/NUiConE.2011.6153263Search in Google Scholar
10. Abtahi, M, Rusch, LA. Mitigating of scintillation noise in FSO communication links using saturated optical amplifiers. In: Proc. - IEEE Mil. Commun. Conf. MILCOM. IEEE, Washington, USA; 2006.10.1109/MILCOM.2006.302382Search in Google Scholar
11. Rani, N, Singh, P, Kaur, P. Mitigation of scintillation effects in WDM-FSO system using homodyne detection. Optik 2021;248:168165. https://doi.org/10.1016/j.ijleo.2021.168165.Search in Google Scholar
12. Fadhil, HA, Amphawan, A, Shamsuddin, HA, Hussein Abd, T, Al-Khafaji, HM, Aljunid, S, et al.. Optimization of free space optics parameters: an optimum solution for bad weather conditions. Optik 2013;124:3969–73. https://doi.org/10.1016/j.ijleo.2012.11.059.Search in Google Scholar
13. Grover, M, Singh, P, Kaur, P, Madhu, C. Multibeam WDM-FSO system: an optimum solution for clear and hazy weather conditions. Wirel Pers Commun 2017;97:5783–95. https://doi.org/10.1007/s11277-017-4810-2.Search in Google Scholar
14. Saleh, MA, Abass, AK, Ali, MH. Enhancing performance of WDM-RoFSO communication system utilizing dual channel technique for 5G applications. Opt Quant Electron 2022;54:1–11. https://doi.org/10.1007/s11082-022-03857-8.Search in Google Scholar PubMed PubMed Central
15. Sood, A, Kaushik, R. 4 × 20 Gbps-60 GHz hybrid RoF-FSO transmission link for last mile connectivity. J Opt 2023;53:1095–105. https://doi.org/10.1007/s12596-023-01301-y.Search in Google Scholar
16. Vasani, E, Shah, V. An effective design of hybrid spectrum slicing WDM–PDM in FSO communication system under different weather conditions. Wirel Pers Commun 2023;130:777–800. https://doi.org/10.1007/s11277-023-10309-3.Search in Google Scholar
17. Gupta, YK, Goel, A, Tiwari, A, Das, AS. Performance analysis of high-speed MIMO FSO system in various data formats. In: 1st IEEE International Conference on Innovations in High Speed Communication and Signal Processing, IHCSP 2023. IEEE, Bhopal, India; 2023:398–401 pp.10.1109/IHCSP56702.2023.10127215Search in Google Scholar
18. Gupta, YK, Goel, A. Performance analysis of multiple-beam WDM free space laser-communication system using homodyne detection approach. Heliyon 2023;9:e13325. https://doi.org/10.1016/J.HELIYON.2023.E13325.Search in Google Scholar
19. Gupta, YK, Goel, A. EDFA controlled spectral efficient MIMO free space optic links for mitigation of climatic turbulence conditions. Wirel Pers Commun 2023;132:2563–85. https://doi.org/10.1007/s11277-023-10732-6.Search in Google Scholar
20. Kruse, RBMPW, McGlauchlin, LD. Elements of infrared technology: generation, transmission and detection. New York, NY, USA: Wiley; 1962.Search in Google Scholar
21. Kim, II, McArthur, B, Korevaar, EJ. Comparison of laser beam propagation at 785 nm and 1,550 nm in fog and haze for optical wireless communications. Opt Wirel Commun III 2001;4214:26–37. https://doi.org/10.1117/12.417512.Search in Google Scholar
22. Soni, G. Performance analysis of free space optical link under various attenuation effects. Sci J Circ Syst Signal Process 2018;7:43. https://doi.org/10.11648/j.cssp.20180702.11.Search in Google Scholar
23. Bhatnagar, MR, Ghassemlooy, Z. Performance analysis of gamma-gamma fading FSO MIMO links with pointing errors. J Lightwave Technol 2016;34:2158–69. https://doi.org/10.1109/JLT.2016.2526053.Search in Google Scholar
24. Majumdar, AK. Free-space laser communication performance in the atmospheric channel. J Opt Fiber Commun Rep 2005;2:345–96. https://doi.org/10.1007/s10297-005-0054-0.Search in Google Scholar
25. Andrews, LC, Phillips, RL, Young, CY. Laser beam scintillation with applications. Bellingham, USA: SPIE; 2001.10.1117/3.412858Search in Google Scholar
26. Chaudhary, S, Amphawan, A, Nisar, K. Realization of free space optics with OFDM under atmospheric turbulence. Optik 2014;125:5196–8. https://doi.org/10.1016/j.ijleo.2014.05.036.Search in Google Scholar
27. Lema, GG. Free space optics communication system design using iterative optimization. J Opt Commun 2020:000010151520200007. https://doi.org/10.1515/joc-2020-0007.Search in Google Scholar
© 2025 Walter de Gruyter GmbH, Berlin/Boston