Imagine data transferring over your local wireless network at the speeds of light. Light Fidelity or Li-Fi is a ground-breaking innovation that has made it possible. Data communication through optical fibers has already made data communication available at light speeds over long distances. Light Fidelity has filled the space for optical communication in the wireless arena and may replace Wi-Fi networks. A wireless optical data communication technology capable of data rates 100 times greater than Wi-Fi, Li-Fi brings the promise of highly secure internet communication without any radio interference. Li-Fi is based on IEEE standard IEEE 802.15.7—similar and compatible with Wi-Fi standard IEEE 802.11.
What is Li-Fi?
Light Fidelity (Li-Fi) is a visible light communication (VLC) technology. Unlike Wi-Fi, which uses radio frequencies for data communication, Li-Fi utilizes visible light and infrared light spectrum for internet data communication. The transceiver is a light source that transmits data by varying the light intensity. The light source on the transceiver is a LED, and the data is received by a photo-detector. The modulated light intensity is decrypted by a microcontroller to regenerate digital data from light waves.
Li-Fi was first demonstrated by professor Harald Haas at the TED Global talk in 2011. As the technology uses visible and infrared light waves for data communication and modulates light intensity instead of frequency, Li-Fi is far more cost-effective compared to Wi-Fi. It offers a wider frequency band of 400 THz compared to 300 GHz of Wi-Fi. Therefore, it is possible to connect several devices with a Li-Fi network without any data latency. Li-Fi promises to be highly secure as data could not be accessed in the absence of light. Li-Fi is capable of topping up to 42.8 Gbit/s while Wi-Fi has a maximum data rate of 300 Mbps. While the network coverage of a Wi-Fi network is greater than Li-Fi, Li-Fi is better at operating in high-density environments. The network coverage of the Li-Fi network can still be adjusted, extended, or limited simply by altering the light intensity. While a WiFi network requires repeaters and routers to extend range, Li-Fi networks can be extended by syncing plain light sources.
Li-Fi enables data transmission through any light source, such as an LED bulb, street lamp, or television screen. The device act as both a light source and as an internet transceiver. Li-Fi will be most useful for public wireless networks like the ones in streets, hospitals, schools, and airplanes. In a Li-Fi network, the receiver needs to be within reach of the light source. You may think of Li-Fi as surfing the internet under a light bulb or street lamp or before a television set. Though the visible light band is used in Li-Fi, the light is low intensity, or infrared and so remains invisible to the human eye.
How Li-Fi works?
Li-Fi mainly uses the band of visible light spectrum between red (400 THz) and violet (800 THz). The two main components in data transmission are a LED light and a photodetector. Li-Fi works by modulating the amplitude of light in a well-defined and uniform pattern. The LED light that acts as transmitter flickers at a speed that takes less than a microsecond. When the LED is ON, it is deciphered as logical ‘1’, and when the LED is OFF, it is deciphered as logical ‘0’. Since the flickering of a light source occurs in a time less than a microsecond, it remains imperceptible to human eyes. On the receiver side, the flickering of light waves is detected by a photodetector, which decrypts the binary ‘1’s and ‘0’s by interpreting the time period of LED switching. Therefore, Li-Fi operates on a very simple and straightforward principle. The digital data is encrypted on visible light waves by high-speed switching of LED and decrypted by detecting the high-speed switching with the help of a highly-sensitive photodetector.
Advantages of Li-Fi over Wi-Fi
Li-Fi is 100 times faster than WiFi. The data speed of a WiFi network ranges between 11 to ~300 Mbps. The typical data speed in the Li-Fi network is 10~20 Gbps. The data speed of a Li-Fi network can top up to 224 Gbps. Li-Fi offers a 100x data speed at a hardware cost of 10 times less than a WiFi network. All that is needed to build a Li-Fi network is an LED, a photodetector, and a microcontroller. Any light source can act as a data transmitter or transceiver, so a Li-Fi network can be extended endlessly and made available anywhere; it will be possible to connect unlimited devices with a Li-Fi network. It utilizes a radio spectrum 400 THz wide that is 10,000 times greater than the frequency band used by WiFi.
A major advantage of Li-Fi is that it operates without any interruption. The visible light waves are neither interrupted nor interfere with radio waves. This makes Li-Fi a highly suitable internet transceiver to use in airplanes and ships. Because light waves used by Li-Fi do not penetrate through walls, there is no chance of intercepting Li-Fi signals and hacking the end devices.
Disadvantages of Li-Fi
The dependency of Li-Fi on the visible light spectrum does impose limitations on the use of this technology. First of all, as Li-Fi is based on the modulation of light waves, the maximum range of a Li-Fi transceiver is limited to 10 meters. In the outdoors, the data transmission speed of a Li-Fi network can be affected by sunlight and other visible light sources. Indoors, the network coverage is obviously limited as the visible light waves cannot penetrate through walls; even opaque obstructions within a room can restrict network coverage. Li-Fi networks require a close line of sight between the LED source and the photodetector. This may compromise the practicality of Li-Fi in many situations.
Applications of Li-Fi
Some of the practical applications of Li-Fi networks include underwater communication, military communication, virtual reality, augmented reality, connected cars, and wireless internet networking in hospitals, schools, airplanes, ships, and retail stores. As Li-Fi signals do not interfere with radio waves, it is best suited to high-speed internet in airplanes and ships. The absence of electromagnetic interference also makes Li-Fi suitable for internet connectivity in hospitals, where Wi-Fi signals can interfere with electronic signals from monitoring equipment.
Li-Fi is useful for internet connectivity where electromagnetic interference is not acceptable. For example, Li-Fi can provide a safe and secure network connection within a power plant. The Li-Fi networks using infrared spectrum can also be used for wireless internet underwater. Additionally, the technology is capable of rendering internet services unaffected by natural disasters such as earthquakes and hurricanes as it operates without routers, antennas, modems, signal repeaters, and amplifiers.
Li-Fi has scope to use for car-to-car communication as well as deployment of IoT in traffic management. It can be installed and utilized in both connected cars and many smart city applications, as well as high-speed internet for home and office automation.
Li-Fi is expected to have a market worth of $115 billion in 2022. As LED prices drop, Li-Fi is expected to be more profitable in the future. While, this growth is encouraging, there are major challenges to face. The IEEE 802.15.7 standard that Li-Fi is based on is now considered obsolete. The standard strictly requires a revision to maintain Li-Fi as an emerging technology. In fact, with the introduction of Optical – Orthogonal Frequency Division Multiplexing (O-OFDM), the entire VLC technology needs a re-standardization.
Li-Fi is a promising and fascinating technology that has significant advantages over Wi-Fi in terms of data rate, connectivity, environment density, security, and reliability. It promises to deliver uninterrupted high-speed internet indoors and a limited range outdoors. Finally, Li-Fi can be used in places inaccessible or where radio interference is a major issue resulting in either no internet access or access only to low-speed internet.
You may also like:
Filed Under: Applications, What Is, Wireless