A Comprehensive Survey on Optical Scattering Communications: Current Research, New Trends, and Future Vision

To meet high data rate requirements of future wireless communication systems, there is a need for advanced communication technologies that could be used in combination with existing wireless RF technologies. Recently, optical wireless communication (OWC) has been extensively investigated as an attractive alternate technology to RF. OWC uses the optical carrier to convey data, with wavelengths ranging from ultraviolet (UV) to infrared (IR) to visible light. In the past years, there is a spike in interest over optical scattering communications (OSCs) employing UV wavelengths, thanks to the recent advances and rapid developments in deep UV light-emitting diodes (LEDs), laser diodes, and solar-blind UV filters and detectors. The unique atmospheric scattering and absorption properties of the deep UV band, which is solar-blind at the ground level, are the motivation for the recent development of the OSC systems. However, there is a clear gap in the existing literature that the OSC systems are yet to be systematically surveyed for their applicability to future wireless communications. In this context, this paper bridges the gap by providing the first contemporary and comprehensive survey on recent and new advancements in the OSCs, commonly known as UV communications. In summary, this survey is expected to provide a largely missing articulation between various aspects of UV communications. To be easy to follow, we commence our discourse by surveying the propagation concepts and historic evolution of UV communication systems. Next, we provide a detailed survey on UV channel modeling because accurate channel characterization is important for efficient system design and performance optimization of UV communication systems. We discuss various UV channel characterization efforts thus far made. Then, we present a classification to analyze current OSC system designs. Importantly, we survey recent advancements in the NLOS UV communication systems that include the application of artificial intelligence, artificial neural networks, game theory, orbital angular momentum, etc. Moreover, we conduct a comprehensive survey on recently documented UV-based indoor communication systems. Finally, we point out several key issues yet to be addressed and collate potentially interesting and challenging topics for future research. This survey is aptly featured by in-depth discussion and analysis of UV communication systems in various aspects, many of which, to the best of authors' knowledge, are the first time presented in this field.