Li-Fi: Future Application of Light for Communication

Li-Fi is not likely to replace Wi-Fi completely, but the use of two together i.e. Wi-Fi and Li-Fi can prove to improve quality of life, says Dr. Prakash Barjatia, Indian Society of Lighting Engineers.

Today, due to the revolution in Information Technology (IT) almost everybody is aware of the term “Wi-Fi”, but a very few including intellectuals are aware about the term “Li-Fi”. So, let us see how Li-Fi is complimentary to Wi-Fi, and its potential in today’s communication system.

First let us see, what is Wi-Fi?
Invented way back in 1990s, Wi-Fi (Wireless Fidelity) is used to transmit more than half of the world’s Internet connections today. Since the technology uses radio waves to transmit data, it is available everywhere, from hotels to car parks to bus terminals. Even the remotest places, which have trouble connecting to Internet, can easily be connected by Wi-Fi.

Now let us turn to Li-Fi
Li-Fi (Light Fidelity) technology is very new and was proposed by the German Physicist Harald Haas in 2011. It is also a wireless networking technology but which uses light emitting diodes (LEDs) for transmission of data. It refers to Visible Light Communication (VLC) technology that uses light as medium to deliver high-speed communication in a manner similar to Wi-Fi.

Why Li-Fi or Visible Communication System?
The frequency spectrum that is available in the atmosphere consists of many wave regions like X-rays, Gamma rays, U-V, IR, visible light rays, radio waves, etc. Any one of the above waves can be used in the upcoming communication technologies but why the Visible Light is preferred? The reason behind this is the easy availability and lesser harmful effects that occur due to these rays of
light. VLC uses the visible light between 780 NM and 375 NM as medium which are less dangerous for high-power applications, and also humans can easily perceive it and protect themselves from the harmful effects whereas other wave regions have following shortcomings:
• Radio waves are expensive and less secure due to interference and possible interception etc.
• Gamma rays are harmful while handling due to their proven adverse effects on human health
• X-Rays have health issues, similar to Gamma Rays
• Ultraviolet Rays can also be dangerous for the human body when exposed continuously
• Infrared Rays due to high safety regulation, can only be used with low power.

Concluding, visible light from red to
blue of the electromagnetic spectrum does not cause any harm to the mankind, provide larger bandwidth and also have a promising future in the communication field.

How Li-Fi works?

Li-Fi technology is a wireless communication system based on the use of visible light. The principle of Li-Fi is based on sending data by amplitude modulation of the light source in a well-defined and standardised way. Only Li-Fi-enabled LED light bulbs are capable of altering illumination levels so that when the bulb is switched on, not only does it generate light but also creates a wireless network in the room. This happens so fast that the naked eye cannot perceive it. Not all LED bulbs will be able to transmit data, though. Since LED bulbs have a built-in driver for control (which helps the light turn on, off, or dim in a fraction of a second), by coding data into the driver, the bulb could be used as a wireless data transmitter.

Potential Applications of Li-Fi
Medical applications: Operation Theatres (OTs) do not allow Wi-Fi due to radiation concerns. To overcome this and to make OT tech savvy, Li-Fi can be used to access internet and also to control medical equipment. This will be beneficial for conducting robotic surgeries and other automated procedures.
In aircrafts: Wi-Fi is not used in aircrafts, because it may interfere with the navigational systems of the pilots whereas Li-Fi can easily provide high speed Internet via every light source available inside aircrafts.
Underwater applications: Li-Fi can even work for Underwater ROVs (Remotely Operated Vehicles) where Wi-Fi fails completely, thereby throwing open endless opportunities for military underwater applications.
Educational applications: Due to its speed, it can augment or replace Wi-Fi for educational and other applications.
Disaster management: Li-Fi can be used as a powerful means of communication in times of disaster such as earthquake or hurricanes. Since Li-Fi pose no obstruction in subway stations and tunnels, it can be used in common dead zones for most emergency communications.
Applications in power plants: Power plants specifically nuclear power plants need fast, inter-connected data systems so that demand, grid integrity and core temperature can be monitored. Since radio communication interference is experienced in sensitive areas surrounding these power plants, Li-Fi can offer safe, abundant connectivity.
Traffic management: At traffic signals Li-Fi can be used to communicate with passing vehicles (through the LED lights of the cars etc) which can help in managing the traffic in a better manner resulting into smooth flow of traffic and reduction in accident. Also, LED car lights can alert drivers when other vehicles are too close.
Mobile connectivity: Mobiles, laptops, tablets, and other smart phones can easily connect with each other. The short-range network of Li-Fi can yield exceptionally high data rates and higher security.
Replacement for other technologies: Since Li-Fi doesn‘t work using radio waves, so it can be easily used in places where Bluetooth, Infrared, Wi-Fi, etc. are banned.

Future Scope
As light is everywhere and free to use, there is a great scope for the use and evolution of Li-Fi technology. If this technology matures, each Li-Fi Bulb can be used to transmit data. As the Li-Fi technology becomes popular, it will lead to a cleaner, greener, economical, and safer communication system. Although Li-Fi promises to solve issues such as, shortage of radio-frequency bandwidth and eliminates the disadvantages of radio communication technologies, but it is also associated with short range and the need of a light source. As such Li-Fi is not likely to replace Wi-Fi completely, but the use of two together i.e. Wi-Fi and Li-Fi can prove to improve quality of life.



Dr. Prakash Barjatia,
Governing Body Member,
Indian Society of Lighting Engineers

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