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?
Li-Fi is sometimes referred to as light-based Wi-Fi because it transmits data by light rather than radio frequencies. Li-Fi can provide a data transmission speed of around 100 Gbps as compared to Wireless Fidelity (Wi-Fi). Currently, Wi-Fi networks rely on Radio Frequency (RF) waves, but there is a constraint on the usage of the RF spectrum.
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 high-speed Li-Fi network transmits data to a device (downlink), such as a laptop or a tablet, using the light from LED lamps and receiving it from the device transmitter, which delivers light signals back to the lamp. Li-Fi technology is the superset of Visible Light Communication (VLC) that forms bidirectional, high-speed mobile networking and data connectivity solutions that provide wireless internet connections at speedy rates.
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
Li-Fi technology is capable of transmitting information at high speeds over Visible Light (VL), Utraviolet (UV) and Infrared (IR) spectrums. The LiFi technology currently uses VL sources such as LED lamps for downlink operations and IR LEDs for uplink operations. The most active standard approved by the IEEE in 2011 for Visible Light Communication is IEEE 802.15.7 (https://standards.ieee.org/ieee/802.15.7/6820/). Mobile-to-mobile (M2M), fixed-to-mobile (F2M), and infrastructure-to-mobile (I2M) communications are all included in this standard. The major goal of the VLC standard is to concentrate on short-range mobile-to-mobile and fixed-to-mobile communications at high rates for information exchange, and medium-range communications for low-speed intelligent traffic systems. The IEEE 802.15.7 standard defines the physical layer (PHY) and media access control (MAC) layers for VLC/LiFi.
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.
Parameters | Wi-Fi | Li-Fi |
|---|---|---|
Operation | Wi-Fi transmits data using radio waves with the help of Wi-Fi router | LiFi transmits data using light sources (presently LED bulbs) |
Interference | 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 patent data in this article shows information related to LiFi technology, including the patent filing trend across the globe and the top-rated assignees.
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.
Conclusion
Li-Fi technology aims to deliver high-speed wireless data connectivity using visible light sources. The Li-Fi technology enables intense data transmission facilities in diverse areas such as manufacturing processes, industrial automation systems, and education purposes due to the minimum number of equipment requirements and ease of flexibility. It can also be utilized for traffic control, underwater communication, and Internet connection to the outside. Additionally, it can be used in aggregated or hybrid fashion in conjunction with Wi-Fi, depending on the technology. Furthermore, several industries have already launched different products that support Li-Fi connectivity, and the LiFi market is experiencing intense competition. Nearly every town in the globe has LED lighting installed, and by combining a microchip with these LEDs, it is possible to turn each light source into a data source that can facilitate data transmission. Li-Fi makes communication on this planet safer, more cost-effective, and more environmentally friendly. Thus, Li-Fi technology provides a more efficient and secure network that can meet the future demand for high-speed wireless connectivity.
