Review of fibreless optical communication technology: history, evolution, and emerging trends

In the present era of technology, it is quite fascinating to design a system capable of transmitting information from one end to another by using the optical spectrum. This system differs from optical fibre communication in terms of channel medium. Optical fibre technology uses the end-to-end physical connection via fibre. In contrast, Light-based wireless communication networks, also known as wireless optical communication (WOC) networks or fibreless optical communication networks, use light as a carrier and air as an unguided propagation media for transmission. Fibreless optical communication eliminates the need for Licensing and Buried Fibre Cables; also, its installation is relatively easy. This survey article describes the evolution of WOC technologies right from the old methods of communication to today’s deep-space optical satellite communication. This article briefly describes the WOC system working principle, categorization of wireless optical systems (based on the carrier frequency wavelength, distance covered, and application), different modulation techniques adopted for wireless optical communication, challenges associated with channel medium and channel modelling, performance analysis of WOC system, various application areas of WOC network, commercial developments in the field of WOC, and some other emerging trends associated with WOC.

A Self-Powered Transparent Photodetector Based on Detached Vertical (In,Ga)N Nanowires with 360° Omnidirectional Detection for Underwater Wireless Optical Communication

Underwater wireless optical communication (UWOC) is a wireless communication technology using visible light to transmit data in an underwater environment, which has wide applications. Based on lift-off (In,Ga)N nanowires, this work has proposed and successfully demonstrated a self-powered photoelectrochemical (PEC) photodetector (PD) with excellent transmissivity. The transparent functionality of the PD is critical for 360° omnidirectional underwater detection, which was realized by detaching the (In,Ga)N nanowires from the opaque epitaxial substrates to the indium tin oxide (ITO)/glass. It was also found that the insulating SiO2 layer can enhance the photocurrent by about 12 times. The core–shell structure of the nanowires is beneficial for generating carriers and contributing to the photocurrent. Furthermore, a communication system with ASCII code is set to demonstrate the PD detection in underwater communication. This work paves an effective way to develop 360° omnidirectional PDs for the wide applications in UWOC system and underwater photodetection.

Filter bank multi-carrier review article

Future wireless networks are researching how to fulfill the growing demand for wireless optical communication. The increased usage of mobile devices and sensors in the real world has resulted in this increasing demand. The fifth-generation (5G) wireless network is the most promising wireless network in the future, with the potential to improve various performance metrics such as spectrum and energy efficiency, high capacity, and low latency. Orthogonal frequency division multiplexing (OFDM) can be produced using cyclic prefix and Fast Fourier Transforms to fight extreme multipath fading. Filtered OFDM, such as Filter-Bank Multi-Carrier (FBMC), can be used to circumvent this limitation. The usage of FBMC to improve the performance of 5G networks is discussed in this paper, along with several hot issues like visible light communication, cognitive radio, and multiple-input multiple-output that FBMC may be utilized with to improve communication.