Light Fidelity (Li-Fi): Wireless Optical Networking Technology
Article contributed by Mr. Vinod Mishra, Assistant Professor, Faculty of Technology and Computer Applications
Li-Fi is a wireless optical networking technology that uses visible light from LED’s for data transmission. Li-Fi is a communication system which is capable of data transmission at high speed over the visible light, ultraviolet and infrared spectrum. At present only LED lamps can be used for the transmission of visible light  . it is similar to Wi-Fi the only difference is that Wi-Fi uses radio frequency to transmit data whereas Li-Fi uses visible light. Li-Fi provides several advantages over Wi-Fi most important is wider bandwidth and higher transmission speed. The visible light spectrum is 10,000 times larger than the entire radio frequency spectrum so it has no capacity limitation  . Li-Fi is expected to be 10 times cheaper than Wi-Fi
Li-Fi is more useful in aircraft cabins, hospitals and nuclear power plants for avoiding electromagnetic interference
It is predicted that in future home and building automation will be highly dependent on the Li-Fi technology as it is very secure and fast. As light cannot penetrate through walls, the signal can not be hacked from a remote location.
The block digram of simple Li- Fi system is as given below.
The transmitter section includes the input, timer circuit and an LED bulb. The input of the transmitter can be any kind of data like text, voice. The timing circuit provides the necessary time interval among every bit and these are transmitted to the receiver end in the form of LED flashes.
The Receiver section includes photodiodes as well as amplifier.
Photodiode receives the LED bulb flashes then chenges the flashes in to electrical signals.
Amplifier receives the signal from the photodiode and amplifies to provide the output.
Difference between Li-Fi and Wi-Fi
|Work of operation
|Transmission of data using LED bulb
|Transmission of data using radio waves
|Present IrDA(Infrared Data Association)
|Interference issue from nearby access point
|more secure data transfer
|require security technique
|Data Transfer Speed
|Data transfer speed between 1Gbps to 20 Gbps
|150 Mbps with WLAN11n
|Frequency of operation
|10,000 times frequency spectrum of radio waves
|2.4GHz, 4.9GHz and 5 GHz
|work in high dense environment
|work in less dense environment
|lamp driver, LED bulb and photodetector
Application of Li-Fi
As Li-Fi uses light from LED which cannot penetrate through walls and doors . this makes it more secure and it can be used in variety of application.
Aviation– Li-Fi based data transmission will not interfere with equipment on the Aircraft.
Hospital- Li-Fi system could be better system which has little effect on medical instrument.
Vehicles- Vehicles could communicate with one another via front and back light to increase road safety.
Industrial Automation- It can be used in Industry by replacing cables for communication.
1· “Comprehensive Summary of Modulation Techniques for LiFi | LiFi Research”. www.lifi.eng.ed.ac.uk. Retrieved 16 January 2018.
3.Haas,Harald (19 April 2013)“High-speed wireless networking using visible light”.SPIE Newsroom. doi:10.1117/2.1201304.004773.
5.Li-Fi Internet at the Speed of Light, by Ian Lim, the gadgeteer, dated 29 August 2011 Archived 1 February 2012 at the Wayback Machine