We are familiar with Wi-Fi (Wireless Fidelity), which uses 2.4-5GHz RF to deliver ubiquitous wireless internet access. Wi-Fi provide access to internet within the premise be it a house, school, building, mall etc and offers a typical bandwidth of 50-100 megabits per second (Mbps) using IEEE802.11n standard. This is a good match to the speed of most current internet services, but it is insufficient for moving large data files like HDTV movies, music libraries and video games. Especially in the today tech world where we are using cloud services to fetch and store data the bandwidth offer by RF technologies like Wi-Fi may not be sufficient. In addition RF technologies may not be efficient in providing newer desired capabilities like precision indoor positioning, gesture recognition etc.

Optical wireless technologies sometimes called Visible Light Communication (VLC), and more recently referred to as Li-Fi (Light Fidelity), on the other hand offer an entirely new paradigm in wireless technologies in terms of communication speed, flexibility and usability.

Li-Fi as a superset of different optical wireless technologies involving communication, positioning, natural user interfaces and many more

Visible Light Communication (VLC)

VLC offers optical wireless communications by using visible light. Today, it is seen as an alternative to different RF-based communication services in wireless personal-area networks. An additional opportunity is arising by using current state-of-the-art LED lighting solutions for illumination and communication at the same time & with same hardware. This can be done due to the ability to modulate LEDs at speeds far faster than the human eye can detect and still providing artificial lighting. Thus while LEDs will be used for illumination, their secondary duty could be to 'piggyback' data communication onto lighting systems. This will be particularly relevant in indoor 'smart' lighting systems, where the light is always 'on.' Outdoor use includes intelligent traffic systems to exchange data between vehicles, and between vehicles and road infrastructure like traffic lights and control units. Driven by the progress of LED technology, visible light communication is gaining attention in research and development. The VLC Consortium (VLCC) in Japan was one of the first to introduce this technology. After establishing a VLC interest group within the IEEE 802.15 wireless personal-area networks working group, the IEEE 802.15.7 task group was established by the industry, research institutes and universities in 2008. The final standard was approved in 2011. Data rates are supported from some 100 kbps up to 100 Mbps using different modulation schemes.

Li-Fi-the superset of VLC & other optical wireless technologies

VLC represents only a fraction of what appears to be a much larger movement towards optical wireless technologies. This larger world has been dubbed 'Li-Fi' (Light Fidelity) Li-Fi comprises several optical wireless technologies such as optical wireless communication, navigation and gesture recognition applied for natural user interfaces. Thus it provides a completely new set of optical technologies and techniques to offer users add-on as well as complementary functionalities compared to well-known and established RF services.

What is Li-Fi

Li-Fi comprises a wide range of frequencies and wavelengths, from the infrared through visible and down to ultraviolet spectrum. It includes sub-gigabit and gigabit-class communication speeds for short, medium and long ranges. Unidirectional and bidirectional data transfer using line-of-sight/ diffuse links, reflections etc. It is not only limited to LED or laser technologies or to a particular receiving technique. Li-Fi is a framework for all of these providing new capabilities to current and future services and applications.

Conclusion

First applications of Li-Fi have been put to use already, for example, in hospitals where RF signals are a threat due to interference problems with medical equipment such as blood pumps and other life supporting instruments; Axiomtek Europe presented such a product at the Embedded World exhibition in Nürn-berg, Germany. A prototype of a mobile phone with VLC system was presented by Casio at the Consumer Electronics Show in Las Vegas. In the coming years, we will see more Li-Fi products entering the market, both in the industrial as well as consumer markets.

      GigaDock-Optical         GigaBeam-Bi-Directional     GigaShower-Unidirectional
     Wireless Charging                  Communication                   Communication

GigaSpeed usage models of Li-FI (Images courtesy: TriLumina Corp.)

By Manik Modgil - 3rd year ECE Student, Chitkara University, Punjab

References
https://en.wikipedia.org/wiki/Li-Fi
www.lificonsortium.org/technology.html