Invented 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 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. Thus, Li-Fi could turn LED light bulbs into network access points.

According to Raja Mukherjee, President & Country Head – Illumination, Bajaj Electricals Ltd, “Li-Fi is a VLC based technology that make light as a media of communication replacing the cable wire communication.”

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While radio frequencies are becoming congested, with more devices trying to connect and overloading networks, the visible light spectrum is an untapped resource with a large bandwidth suitable for stable simultaneous connection of a vast array of Internet of Things (IoT) devices. Signify, formerly known as Philips Lighting, claims to be the first global lighting company to offer Li-Fi-enabled luminaires from our existing office lighting portfolio. Sumit Joshi, Vice Chairman and Managing Director, Signify India Innovations Ltd (formerly known as Philips Lighting India), said, “Being a lighting company, we ensure that our customers benefit from the finest quality energy efficient lighting along with state-of-the-art connectivity.”

Why Li-Fi

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 these waves can be used in the upcoming communication technologies but why the visible light is preferred? The reason behind is the easy availability and lesser harmful effects that occur due to these rays of light, opines Dr. Prakash Barjatia, Governing Body Member, Indian Society of Lighting Engineers (ISLE). He explains, “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.”

Thus, 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 whereas the 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.

How does Li-Fi work?

Explaining the working principle of Li-Fi, Dr. Barjatia said, “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.”

According to Mr Mukherjee, “All the existing wireless technologies utilise different frequencies on the electromagnetic spectrum. While Wi-Fi uses radio waves, Li-Fi hitches information through visible light. Given this, the latter requires a photo-detector to receive light signals and a processor to convert the data into stream-able content. As a result, the semiconductor nature of LED light bulbs makes them a feasible source of high-speed wireless communication.” Li-Fi works in such a way that each luminaire is equipped with a built-in modem that modulates light at speeds imperceptible to the human eye. “The light is detected by a Li-Fi USB key or dongle plugged into the socket of a laptop or tablet. In future such technology will be inbuilt into laptops, mobile phones and devices,” elucidates Mr Joshi. He further claims, with Signify Li-Fi-enabled luminaires, customers get the double benefit of quality, energy-efficient LED light and a highly secure, stable and robust connection as Li-Fi’s bandwidth is more than 1,000 times the size of the radio spectrum.

Application areas of Li-Fi

Dr. Prakash Barjatia of ISLE explains potential application areas of Li-Fi as:

  • 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/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.

Raja Mukherjee of Bajaj Electricals also acknowledges that Li-Fi can be used in hospitals, workplace, schools, and retail.

Highlighting the Indian scenario, Sumit Joshi of Signify India informs, “There is a lot of potential for Li-Fi in India, with millions of Internet devices are being added into the connected ecosystem every day. Moreover, with more and more digital content being consumed, in the future, consumers will demand a faster Internet connection that can be enabled through Li-Fi.”

Li-Fi is ideal for use in areas that are sensitive to radio frequencies (e.g. hospitals, clinics, factories, schools). It is also highly suited for use in banks, schools, government and industry, indeed anywhere where Wi-Fi is poor or unavailable (e.g. multi-tenancy buildings, underground). It offers a secure, personal connection for anyone concerned about data privacy, assures Mr Joshi.

Can Li-Fi replace Wi-Fi?

A few experts say, Li-Fi has so far only been used for scientific and academic purposes, things that are rarely ever used in daily life. It has a very short range, and constantly needs a light source. “When a person is traveling and does not have a Li-Fi enabled light source nearby, it will not be possible to connect to the Internet. Despite the fast speeds and the few benefits, Li-Fi isn’t likely to replace Wi-Fi in the near future,” cautioned Mr Mukherjee.

However, he adds, “The use of the two together can prove to be beneficial, but alone, Li-Fi isn’t capable of producing results as brilliant as the studies suggest. Until the downsides of Li-Fi have been dealt with, Wi-Fi will continue to be popular and critical to maintain our quality of life and the so-called spectrum crunch will fail to have any effect on the use of this wireless technology.”

Dr. Prakash Barjatia also admits: “It (Li-Fi) is 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.”

The Li-Fi Future

By definition, Li-Fi is networked bi-directional communication. It is an additional layer of wireless networking within the heterogeneous group of radio networks. It allows mobility, handover and multiple user access— features that make it different from VLC.

We have often attempted to access the Internet through Wi-Fi in an indoor enterprise environment only to find ourselves staring at a screen with an incessant buffering symbol! Enterprise and retail locations such as restaurants, movie theatres, parking garages, or hospitals often times provide spotty cellular reception due to infrastructure barriers such as walls and ceilings. Li-Fi provides stable Internet connectivity to such users, if they are located directly below or across a light source providing an alternative means of connectivity in these types of environments, where Wi-Fi is not suitable. But what happens when Li-Fi users move around from Wi-Fi station to Li-Fi station? “Li-Fi supports multi-point connections allowing a Li-Fi user to move across an area with many Li-Fi light fixtures without experiencing service interruptions. In similar fashion to wireless roaming, a mobile client device’s Internet session will get handed over to the nearest station without terminating it,” replies Mr Joshi.

The other question is whether we want to live with all these electro-magnetic waves around us or do we prefer to get rid of all of those? “When we have Wi-Fi, we don’t have just one network, we have a lot of networks. Li-Fi is just data coming through light, hence far safer for use as compared to Wi-Fi,” Mr Joshi assures.

Signify, formerly known as Philips Lighting, is one of the pioneers in the field of Li-Fi. Talking about the progress his company made in this front, Mr Joshi of Signify India Innovations said, “With Li-Fi from Signify, you get the double benefit of quality, energy efficient LED light and a secure and highly stable, robust and fast broadband connection. We provide everything you’ll need, from light sources and modems to USB access keys.”

With its efforts and constant drive for Li-Fi in the market, Signify has already have 7 pilot installations in India across different segments, including banks, information technology, co-working spaces, B2G, and infrastructure. The company was also invited by the Prime Minister’s Office (PMO) and Government of Gujarat to showcase Li-Fi as a futuristic technology at the Vibrant Gujarat summit.

By Subhajit Roy, Group Editor


Working of Li-Fi
When a constant current source is applied to an LED bulb, it emits a constant stream of photons observed as visible light. When this current is varied slowly, the bulb dims up and down. As these LED bulbs are semiconductor, the current and optical output can be modulated at extremely high speeds that can be detected by a photo-detector device and converted back to electrical current.
 The intensity modulation is too quick to be perceived with the human eye and hence the communication seems to be seamless just like RF. So, the technique can help in transmitting high-speed information from an LED light bulb. However, it’s much simpler, unlike RF communication which requires radio circuits, antennas, and complex receivers.
Li-Fi uses direct modulation methods similar used in low-cost infrared communications devices like remote control units. Moreover, infra-red communication has limited powers due to safety requirements while LED bulbs have intensities high enough to achieve very large data rates.

(Source: Bajaj Electricals)