ABSTRACT
Visible light communications (VLC) is an evolving technology for forthcoming high data rate communication interfaces in the visible range of the electromagnetic spectrum utilizing LEDs which provide data transmission and room illumination simultaneously. Light Fidelity or Li-Fi, is an amazing invention in 5G visible light communication systems and the forthcoming wireless internet access techniques. In the recent years, white Light Emitting Diodes (LEDs) are considered as an encouraging technology for next generation lighting due to their longer lifespan, low-power requirement and very high efficiency. VLC is well-thought-out as a possible access choice for upcoming 5G wireless communications because of its advantages. VLC technology can also be used in the high precision indoor-positioning and navigation systems underwater communication, vehicle to traffic light, vehicle to vehicle communication and information broadcasting. VLC is an emerging technology in OWC which stimulates international research. These facts result in an increasing throughput requisite from the next generation 5G communication networks, which are anticipated to be deployed beyond 2020. The important features of Light Fidelity (Li-Fi) networks are license-free spectrum, unlimited channel bandwidth, high data rate interfaces and energy efficiency. Li-Fi is a subdivision of the VLC which provides access networks with several users. Visible Light Communication uses different types of modulation schemes based on the requirements for various applications such as Li-Fi, vehicle to vehicle communication, under-water communication, visible light ID system and Wireless Local Area Networks (WLANs). Visible Light Communication (VLC) system which deploys Light-Emitting-Diodes (LEDs) to communicate and blink at speed of light in terms of Giga bits per second (Gbps). The modulation speed of the LEDs are restricted by the residual charge carriers in depletion region during the reverse bias condition of the LEDs. Switching speed of the LEDs are reduced during the reverse biased condition of the LEDs. Carrier sweep out method during reverse bias to enhance the operating frequency of the LEDs was considered as an effective method, so that higher data transfer rate can be achieved. The switching speed or the modulation speed of the LEDs should be improved to enhance data transfer rate. The remaining carriers in the depletion region can be swept outside by connecting the leads of the LEDs for a moment.
