Free-Space Optical (FSO) Communication: Bridging the Gap in High-Speed Point-to-Point Wireless Networks

Abstract

Free-Space Optical (FSO) communication has emerged as a promising solution for high-speed point-to-point wireless networks, offering unparalleled data rates, security, and scalability. However, challenges such as atmospheric turbulence, weather dependency, and alignment issues have hindered its widespread adoption. This paper explores the advancements in FSO technology, focusing on its role in bridging the gap in high-speed wireless communication. We discuss key enabling technologies, including adaptive optics, hybrid FSO-RF systems, and machine learning-based optimization, and evaluate their potential to overcome existing limitations. Furthermore, we highlight applications in 5G/6G networks, satellite communication, and last-mile connectivity, providing insights into the future of FSO as a cornerstone of next-generation wireless networks.

Introduction

As the demand for faster, more reliable, and secure wireless communication increases, traditional radio frequency (RF) systems struggle with issues like spectrum congestion, interference, and limited bandwidth. Free-Space Optical (FSO) Communication has emerged as a promising alternative. FSO uses light to transmit data through free space (air or vacuum), offering benefits such as high bandwidth, low latency, enhanced security, and immunity to electromagnetic interference.

Motivation

Driven by the explosion of data-heavy applications (e.g., 5G, IoT, cloud computing), FSO offers an efficient and secure solution for high-speed, point-to-point communication where fiber deployment is impractical or too costly.

Fundamentals

FSO systems consist of:

• Transmitter (laser/LED),

• Receiver (photodetector),

• Optical antennas,

• Modulation techniques,

• Alignment mechanisms.

The process involves encoding data onto light beams, transmitting them through the atmosphere, and decoding them at the receiver end.

Advantages

• Gigabit-per-second data rates

• License-free spectrum usage

• Strong security due to narrow beams

• Scalable and low-latency performance

Challenges

FSO is susceptible to:

• Atmospheric attenuation (e.g., fog, rain)

• Weather dependence

• Alignment sensitivity

• Limited range

• Scintillation and turbulence

• Security threats

• High deployment cost

• Safety and regulatory concerns

Mitigation strategies include adaptive optics, hybrid FSO-RF systems, beam tracking, and diversity techniques.

Enabling Technologies

Key technologies enhancing FSO include:

• High-power lasers and sensitive photodetectors

• Advanced modulation/coding

• Beam steering/tracking

• Hybrid RF-FSO integration

• AI and machine learning for optimization

• Quantum Key Distribution (QKD) for security

• Energy-efficient design

• 5G and SDN integration

Applications

FSO is applied in:

• Last-mile connectivity (urban/rural broadband)

• Backhaul networks (5G, IoT)

• Enterprise interconnectivity

• Disaster recovery and emergency communications

• Inter-satellite and satellite-to-ground links

Conclusion

FSO communication represents a critical enabler of next-generation wireless networks, offering a scalable, cost-effective, and high-performance solution for point-to-point connectivity. By overcoming existing challenges and exploring new frontiers, FSO technology has the potential to revolutionize the way we communicate, bridging the gap between current limitations and future demands. As research and development efforts continue to push the boundaries of what is possible, FSO communication will play an increasingly vital role in shaping a connected and sustainable future.

References

[1] Ijaz, L. Zhang, M. Grau, A. Mohamed, S. Vural, A. U. Quddus, M. A. Imran, C. H. Foh, and R. Tafazolli, “Enabling massive IoT in 5G and beyond systems: PHY radio frame design considerations,” IEEE Access, vol. 4, pp. 3322–3339, Jul 2016. [2] M. Jaber, M. A. Imran, R. Tafazolli, and A. Tukmanov, “5G backhaul challenges and emerging research directions: A survey,” IEEE access, vol. 4, pp. 1743–1766, Apr 2016. [3] M. Shafi, A. F. Molisch, P. J. Smith, T. Haustein, P. Zhu, P. De Silva, F. Tufvesson, A. Benjebbour, and G. Wunder, “5G: A tutorial overview of standards, trials, challenges, deployment, and practice,” IEEE Journal on Selected Areas in Communications, vol. 35, no. 6, pp. 1201–1221, Jun 2017. [4] M. Z. Chowdhury, M. K. Hasan, M. Shahjalal, M. T. Hossan, and Y. M. Jang, “Optical wireless hybrid networks: Trends, opportunities, challenges, and research directions,” IEEE Communications Surveys & Tutorials, vol. 22, no. 2, pp. 930–966, Second Quart. 2020. [5] M. Z. Chowdhury, M. T. Hossan, A. Islam, and Y. M. Jang, “A comparative survey of optical wireless technologies: Architectures and applications,” IEEE Access, vol. 6, pp. 9819–9840, Jan 2018. [6] U. Siddique, H. Tabassum, E. Hossain, and D. I. Kim, “Wireless backhauling of 5G small cells: Challenges and solution approaches,” IEEE Wireless Communications, vol. 22, no. 5, pp. 22–31, Oct 2015. [7] T. O. Olwal, K. Djouani, and A. M. Kurien, “A survey of resource management toward 5G radio access networks,” IEEE Communications Surveys & Tutorials, vol. 18, no. 3, pp. 1656–1686, Third Quart. 2016. [8] H. A. U. Mustafa, M. A. Imran, M. Z. Shakir, A. Imran, and R. Tafazolli, “Separation framework: An enabler for cooperative and D2D communication for future 5G networks,” IEEE Communications Surveys & Tutorials, vol. 18, no. 1, pp. 419–445, First Quart. 2016. [9] Z. Ghassemlooy, S. Arnon, M. Uysal, Z. Xu, and J. Cheng, “Emerging optical wireless communications-advances and challenges,” IEEE Journal on Selected Areas in Communications, vol. 33, no. 9, pp. 1738–1749, Sep 2015. [10] M. Obeed, A. M. Salhab, S. A. Zummo, and M.-S. Alouini, “Joint optimization of power allocation and load balancing for hybrid VLC/RF networks,” Journal of Optical Communications and Networking, vol. 10, no. 5, pp. 553–562, May 2018. [11] M. R. Palattella, M. Dohler, A. Grieco, G. Rizzo, J. Torsner, T. Engel, and L. Ladid, “Internet of things in the 5G era: Enablers, architecture, and business models,” IEEE Journal on Selected Areas in Communications, vol. 34, no. 3, pp. 510–527, Mar 2016. [12] W. A. Hassan, H.-S. Jo, and A. R. Tharek, “The feasibility of coexistence between 5G and existing services in the IMT-2020 candidate bands in Malaysia,” IEEE Access, vol. 5, pp. 14 867–14 888, Apr 2017. [13] R. I. of Sweden (RISE), “Smartoptics joins research project to develop 100Gbps free-space optical communication solutions.” [Online]. Available: https://www.smartoptics.com/news/smartoptics-joi ns-research-project-develop-100gbps-free-space-optical-communicati on-solutions/ [14] A. Trichili et al., “Roadmap to free space optics,” J. Opt. Soc. Am. B, vol. 37, no. 11, pp. A184–A201, Nov 2020. [15] L. Boccia et al., “Low multipath antennas for GNSS-based attitude determination systems applied to high-altitude platforms,” GPS Solutions, vol. 12, pp. 163–171, Jul. 2008. [16] M. A. Esmail et al., “Outdoor FSO communications under fog: Attenuation modeling and performance evaluation,” IEEE Photonics J., vol. 8, no. 4, pp. 1–22, Aug. 2016. [17] M. S. Awan et al., “Cloud attenuations for free-space optical links,” in Proc. IEEE Int. Workshop Satell. Space Commun. (IWSSC), 2009, pp. 274–278. [18] X. Ruan et al., “Beyond 100G single sideband PAM-4 transmission with silicon dual-drive MZM,” IEEE Photon. Technol. Lett., vol. 31, no. 7, pp. 509–512, Apr. 2019. [19] S. Arnon, J. Barry, G. Karagiannidis, R. Schober, and M. Uysal, Advanced optical wireless communication systems. Cambridge university press, May 2012. [20] L. Grobe, A. Paraskevopoulos, J. Hilt, D. Schulz, F. Lassak, F. Hartlieb, C. Kottke, V. Jungnickel, and K.-D. Langer, “High-speed visible light communication systems,” IEEE communications magazine, vol. 51, no. 12, pp. 60–66, Dec 2013. [21] D. Tsonev, S. Videv, and H. Haas, “Towards a 100 Gb/s visible light wireless access network,” Optics express, vol. 23, no. 2, pp. 1627–1637, Jan 2015. [22] D. Karunatilaka, F. Zafar, V. Kalavally, and R. Parthiban, “LED based indoor visible light communications: State of the art,” IEEE Communications Surveys & Tutorials, vol. 17, no. 3, pp. 1649–1678, Fourth Quart. 2015. [23] Y.-Y. Zhang, H.-Y. Yu, J.-K. Zhang, Y.-J. Zhu, J.-L. Wang, and T. Wang, “Space codes for MIMO optical wireless communications: Error performance criterion and code construction,” IEEE Transactions on Wireless Communications, vol. 16, no. 5, pp. 3072–3085, May 2017. [24] A. Khreishah, S. Shao, A. Gharaibeh, M. Ayyash, H. Elgala, and N. Ansari, “A hybrid RF-VLC system for energy efficient wireless access,” IEEE Transactions on Green Communications and Networking, vol. 2, no. 4, pp. 932–944, Dec 2018. [25] L. Arienzo, “Green RF/FSO communications in cognitive relay-based space information networks for maritime surveillance,” IEEE Transactions on Cognitive Communications and Networking, vol. 5, no. 4, pp. 1182–1193, Dec 2019. [26] H. Haas, L. Yin, Y. Wang, and C. Chen, “What is lifi?” Journal of Lightwave Technology, vol. 34, no. 6, pp. 1533–1544, Mar 2016. [27] Z. Ghassemlooy, P. Luo, and S. Zvanovec, “Optical camera communications,” in Optical Wireless Communications. Springer, Aug 2016, pp. 547–568.

Copyright

Copyright © 2025 Khamni Mohamed Elmbark, Omar Mohammed Abubaker Naser, Hamzah Abdullah Faraj. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.