Optical Wireless Communications for 3D Ubiquitous Intelligent 6G Networks and Beyond

Dear Colleagues,

Ubiquitous connectivity is paramount for 6G networks to ensure reliable communication across diverse environments. Unlike previous generations, 6G aims to provide a hyper-connected world where devices, people, and infrastructure are seamlessly and efficiently interconnected. It guarantees high-speed, low-latency communication accessible to everyone, everywhere, at all times. In these emerging complex network landscapes, traditional rigid 2D networks are becoming bottlenecks for expansion, necessitating flexible, agile 3D networks to achieve 6G KPIs. Optical wireless communication (OWC) is an emerging wireless solution offering flexible, high-speed, ubiquitous 3D connectivity, linking space, air, ground, underwater, and maritime integrative networks. As a backbone, OWC enables reliable communication for short-range applications, including indoor, outdoor, automotive, and Internet of Underwater Things networks, and supports long-range communications for space, satellite, UAVs, HAPs, and backhaul terrestrial communications.

The 6G network brings forward several novel concepts, including the seamless integration of multiple communication technologies such as radio and optical wireless, AI-driven communication network solutions, digital twins for performance optimization, and reconfigurable intelligent surfaces to enhance capacity and coverage. This also entails efficiently integrating emerging technologies with existing network infrastructure to enable seamless communication across various scenarios, from space to underwater environments. While OWC complements existing wireless systems, enhancing coverage, speed, reliability, and latency, several challenges still demand significant innovation and further research to integrate OWC effectively into intelligent 6G networks. This includes advancing core OWC technology and developing 6G compatible solutions.

Signal blockage and line-of-sight requirements can hinder consistent connectivity in dynamic environments. Addressing these issues may involve advanced techniques like beyond-the-light communication, beam steering, and tracking combined with intelligent, reflective surfaces and hybrid RF/optical solutions. Additionally, challenging environmental effects such as atmospheric/underwater turbulence and high attenuation demand significant attention. Hence, further innovation in OWC system design is essential for achieving better power and spectral efficiencies, enhancing resilience to environmental effects, and meeting the growing demand for high-speed, secure, and reliable data transmission in settings where traditional radio frequency communication is limited or impractical. The innovations include developing novel optoelectronic devices like lasers/LEDs and highly sensitive receivers, diversity and MIMO schemes, advanced optics systems, and signal processing and waveform technologies. Furthermore, while OWC offers better security than RF wireless systems, achieving ultra-secure communication remains a critical challenge.

This Special Issue aims to report recent breakthroughs, emerging challenges and opportunities, and novel practical applications of OWC. Researchers are encouraged to address several challenges that require further consideration. Hence, this Special Issue accepts papers on, but is not limited to, the following topics:

• Terrestrial optical wireless communications, including free space optics;
• Non-terrestrial optical wireless communications;
• Underwater optical wireless communications;
• Visible light communications and LiFi;
• Vehicular optical wireless communications (V2V, V2I, and V2X);
• Secure optical wireless communications;
• AI-enabled optical wireless communications;
• Digital twin-based optical wireless communications;
• Reconfigurable intelligent surface (RIS)-assisted optical wireless communication;
• Adaptive and adaptable optics for optical wireless communication;
• Optical wireless backhaul and fronthaul;
• Radio-over-free space optical communications (RoFSOs);
• Visible light positioning (VLP) and sensing;
• Integrated sensing communication and positioning;
• Hybrid radio and optical wireless communications;
• Optical camera communications (OCCs);
• Diversity techniques for optical wireless communications;
• Channel modeling for optical wireless communications;
• Quantum key distribution (QKD) over optical wireless systems and networks.

Dr. Farah Mahdi Al-Sallami
Dr. Sujan Rajbhandari
Dr. Chedlia Ben Naila
Guest Editors

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• optical wireless communications
• underwater optical wireless communications
• visible light communications and LiFi
• vehicular optical wireless communications