Li-Fi (Light Fidelity) — A Visible Light Communication Internet Connectivity Solution

In recent years, the demand for wireless data transmission has increased tremendously due to the increased number of users and wireless devices. Therefore, to meet this increasing demand, Light Fidelity (Li-Fi) technology is a potential candidate that can provide wireless connectivity at speedy rates. Li-Fi is based on Visible Light Communication (VLC), which is a fully wireless technology that uses Light Emitting Diodes (LEDs) for data transmission. In comparison to incandescent light sources, light-emitting diodes (LEDs) have several merits in terms of minimal power consumption, lesser heat generation, compact size, high durability, and high reliability. One of the most important features of LED, which makes it distinctive and powerful over other lighting devices, is its capability of providing illumination and communication simultaneously. Due to the widespread increase in the demand for LEDs for communication purposes, several types of new LEDs have been proposed by several researchers that can be switched at very high speeds so that the flickering effect of LEDs is imperceptible to the human eye.

What is Li-FI?

The term Li-Fi was first coined by Prof. Harald Haas in a TED Global Talk held in July 2011. Haas claimed that Li-Fi can be used in chemical manufacturing facilities, where radio frequencies are too risky and could result in antenna sparks. Also, it can be deployed in traffic control systems that employ a car’s headlights. Haas co-founded pureLiFi, formerly known as pureVLC, a company that manufactures equipment for integrating LiFi products with current LED lighting systems. The first commercially accessible Li-Fi technology is unveiled in September 2013. The Li-1st became the first commercial Li-Fi device in history. The Li-Fi product called Li-Flame, which was introduced in February 2015, made a claim to be the first to provide mobile wireless communications. In 2016, pureLiFi, Lucibel, and a French lighting business introduced the first industrialized Li-Fi solution that has been installed in several places, including Microsoft’s Paris headquarters. Further, the LiFi-XC system was released in October 2017. This system is certified plug-and-play, compatible with USB devices, and compact enough to fit into your upcoming laptop, tablet, or smart appliance. And just last June, pureLiFi created a channel program for IT resellers to add Li-Fi to their product line and provided starter kits for Li-Fi to academic researchers.

How Does Li-Fi Work?

A Li-Fi enabled LED light bulb emits a stream of light (photons) when an electrical current is supplied to it. Since LED lights are semiconductor devices, it is possible to change the brightness of the light very quickly by varying the current through the driver circuit. This enables us to modulate the light at different rates to deliver an informative signal. The transmitted light from LED bulbs fluctuates billions of times each second, which the human eye cannot perceive. After propagating the information signal through the indoor environment, the receiver receives it, which further amplifies the signal, processing and translating the delivered information. This is essentially comparable to deciphering Morse code, but it happens millions of times each second, which is significantly faster. LiFi transmission rates can exceed 100 Gbps, which is 14 times faster than WiGig, also referred to as the fastest Wi-Fi in the world.

Standardization of Li-Fi

The physical layer is categorized into three types namely, PHY I, II, and III. Further, the physical layer employs a combination of different modulation schemes.

  • The PHY I was developed for outdoor use and operates between 11.67 kbps to 267.6 kbps.
  • The PHY II layer enables data rates up to 96 Mbit/s (1.25 Mbit/s to 96 Mbit/s).
  • The PHY III uses a specific modulation technique known as Colour Shift Keying (CSK) for various sources. PHY III is capable of delivering data rates from 12 to 96 Mbit/s.

The PHY I and PHY II layers use On-Off Keying (OOK) and Variable Pulse Position Modulation (VPPM) formats for information transmission. Further, the clock is also included in the transmitted information using Manchester coding which represents logic “0” with “01” OOK symbol and logic “1” with a “10” OOK symbol and both include a DC component. In the case of a consecutive logic zero, the DC component prevents light extinction.

The MAC layer provides three multi-access technologies, such as Peer-to-peer, star configuration, and broadcast mode. In addition, it manages physical layer issues such as protocols for data acknowledgment, collision avoidance, and addressing. Further, there are two more VLC networking standards formed by the Japanese, such as JEITA CP-1221 and CP-1222.





Wi-Fi transmits data using radio waves with the help of Wi-Fi router

LiFi transmits data using light sources (presently LED bulbs)


Several sources of radio interference can disrupt the function of a Wi-Fi network

Does not have any interference issues similar to radio frequency waves.

Feasible Link Length

~ 32 meters (WLAN 802.11b/11g), depending on transmit power and antenna type

~ 10 m

Data Density

Works in less dense environments due to interference related issues

​Works in high-density environments

Patent Analysis

The number of applications filed each year across the world is depicted in the chart. It is thrilling to know that the patent filing trend jumped to a new level of more than 1650 applications in the year 2017–2018. It is because the global LiFi market is anticipated to be driven by a rise in demand for 4G and 5G technology, as well as the constraints on the usage of the RF spectrum. Global Market Insights, Inc. projects that the LiFi market will reach $75.5 billion in value by 2023, growing at a CAGR of 80.8% from 2016. Furthermore, in upcoming years, it is expected to grow as research and development in this field are still ongoing.

The top assignees in the field of LiFi technology are presented here. Among these assignees, Samsung Electronics with a total number of 1425 patents, holds the majority of shares, followed by Here Global and Signify Holding. Currently, Samsung Electronics is a forefront pioneer of smart LED lighting systems, which is going to launch Li-Fi enabled devices. This is because Samsung LEDs developed and manufactured the first Chip Scale Package (CSP) in 2014 and the company unveiled its ground-breaking 200 lm/W product with smart lighting features. In addition to enabling more flexible and compact designs, Samsung LEDs CSP drastically lowers the production and operation cost of LED lighting systems. The other top companies/assignees contributing to this research area include KT, Sony, Guangdong Oppo Mobile Telecommunications, Sony Group, DIGIMARC, Orange, LG Electronics, etc.






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