Light becomes data
What is Li-Fi?
Li-Fi (Light Fidelity) is a wireless communication system that uses light-emitting diodes (LEDs) to transmit data. Professor Harald Haas unveiled the Li-Fi technology during a 2011 TED GLOBAL talk in Edinburgh. Unlike Wi-Fi which uses radiofrequency, Li-Fi technology only needs a light source with a chip to transmit an internet signal through light waves. Technically speaking, Li-Fi is a light communication system capable of transmitting over visible, ultraviolet, and infrared light spectrums at high speeds. At present date, only LED lamps can be used to transmit data in visible light. Li-Fi provides better bandwidth, efficiency, connectivity, and security compared to Wi-Fi system.
How does Li-Fi work?
Li-Fi is a high-speed, fully networked, and bidirectional wireless communication of data using light. Li-Fi consists of several lightbulbs that form a wireless network. An electrical current is applied to the LED light bulb to emit a stream of light (photons). LED bulbs are semiconductor devices, and the light’s brightness flowing through them can be transformed at extremely high speeds.
Figure 1.
Hence the signal can be sent by modulating the light at different rates. A detector can then receive the signal that comprehends the variation in the intensity of light (i.e., signal) as data. When the LED is ON, digital 1 is transmitted, and when it is OFF, 0 is transmitted. The human eye cannot see the intensity modulation. Thus, there is smooth communication like other radio systems, allowing users to connect with Li-Fi-enabled light. Data is transmitted from a LED light bulb and back at high speeds using this technique.
Li-Fi and Visible Light Communication:
Figure 2.
Following are the features of Li-Fi technology:
• Li-Fi (Light Fidelity) works based on VLC (Visible Light Communication) principle.
• Li-Fi transmits data using light intensity modulation.
• Data speeds of about 1GBps have to be achieved in laboratory tests.
• Li-Fi uses visible light of spectrum bandwidth between 400 THz to 800 THz. It uses optical carriers in this range for data transmission and illumination purposes.
• Li-Fi system is operated through modulation schemes such as OOK, VPPM, CSK.
• Peer to peer, star, and broadcast are the modes supported by the Li-Fi system.
• The PHY and MAC layers of the Li-Fi system are defined in IEEE 802.15.7 standard.
• Data is transferred very rapidly and securely due to the LOS (Line of Sight) operation of optical signals.
Figure 3.
There are subtle differences between Li-Fi and VLC terminologies. They are as follows:
➤VLC technology uses visible light part of the light spectrum, whereas Li-Fi technology uses any possible light spectrum for communicating.
➤Wireless communication has many applications such as Wi-Fi, Satellite, LTE, and GSM. Li-Fi is one of the applications of VLC (Visible Light Communication).
➤Infrared and ultraviolet light is being tested in Li-Fi for communication, unlike Visible Light Communication. Speeds of about 40 Gbps have been achieved in the Li-Fi system.
Li-Fi vs. Wi-Fi:
| FEATURE | Li-Fi | Wi-Fi |
| Abbreviation | Light Fidelity | Wireless Fidelity |
| Technology | IrDA compliant devices | WLAN 802.11a/b/g/n/ac/ad standard compliant devices |
| Operating Frequency | Ten thousand times larger than radio frequency spectrum | 5 GHz, 4.9 GHz, and 2.4 GHz |
| Coverage | 10 meters | About 32 meters |
| Data Density | Works in a highly dense environment | Works in a less dense environment |
| Privacy | Walls block light, hence more secure. | Less secured since RF signal can’t be blocked by walls |
| Data Transfer Speed | Faster transfer speed (>1 Gbps) | Slower transfer speed (150 Mbps) |
| Medium of Data Transfer | Light as the data carrier | Radio spectrum as the data carrier |
| Spectrum Range | Light has ten thousand times broader spectrum than radio frequency | The radio frequency spectrum is much less than the light spectrum |
| Cost | Cheaper than Wi-Fi since –No license requirement for light band Lower installation cost | Costlier than Li-Fi since –License required for radio bandHigher installation cost |
| Ecological impact | Low | Medium |
| Market Maturity | Low | High |
| System components | Lamp driver, LED bulb (lamp), and photodetector make up a complete Li-Fi system. | requires routers to be installed, subscriber devices (laptops, PDAs, desktops) are referred to as stations |
| Applications | Used in airlines, operation theatres in the hospitals, undersea explorations, office and home premises for data transfer and internet browsing | Used for web browsing with the help of Wi-Fi kiosks or Wi-Fi hotspots |
| Merits(advantages) | Interference is minor, can pass through salty seawater, works in densely region | Interference is more, can’t pass through seawater, works in less densely region |
Future of Li-Fi Technology:
Companies working on Li-Fi technology:
Examples of some of the Li-Fi products commercially available on the market at present are-
- Kitefin: A military-grade, deployable Li-Fi for defense applications, also from PureLifi.
- Lifi-XC: A Li-Fi dongle from PureLifi.
- MyLiFi Pro: A Li-Fi supported desk lamp from Oledcomm.
The list is growing consistently. Still, as of now, Li-Fi remains a niche technology, not popular among the masses. But that is bound to change soon.
Since its introduction, Li-Fi has been popularized as the technology that would one day replace Wi-Fi and bring forth a new 5G era. This exemplar shift in wireless communication that Haas envisioned in his 2018 paper is very much a possibility, and it simply has not arrived yet.
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