LI-FI

TECHNOLOGY

PRESENTED BY

Dr. SK. Mastan Vali

Li-Fi (Light Fidelity)

• Li-Fi (Light Fidelity) can be thought of as a light-based Wi-Fi

Technology uses The Visible Spectrum

• The term was first used by Harald Haas in his TED

Global talk on Visible Light Communication in 2011

• In October 2011 a number of companies and industry

groups formed the Li-Fi consortium, to promote high-speed

optical wireless systems.

• Researchers at the Heinrich Hertz Institute in Berlin,

Germany, have reached data rates of over 500 megabytes

per second using a standard white-light LED.

LI-FI ENVIRONMENT

PRINCIPLE OF LI-FI TECHNOLOGY

• The heart of this technology is a new generation high

brightness led’s.

• Visible Light Communication.

• These led’s varies in intensity (that is gets on and off) so fast

that a human eye cannot detect it.

• If led is on , then we transmit a digital signal 1,and if the led is

off , then we transmit a digital signal 0.

• A controller is connected at the back side of these led bulbs

to code data to these led’s.

If led is on , then we transmit a digital signal 1,

and if the led is off , then we transmit a digital signal

0.

VISIBLE LIGHT COMMUNICATION

• Li-Fi is a faster and cheaper version of Wi-Fi, which is based on visible light communication

(VLC).

• The visible light communication is a data communication technique using visible light between

400 THz and 800 THz as an optical carrier for data transmission.

Visible Rays

Radio Waves

Ultraviolet Rays

X-raysGamma

rays

• Gama rays,X-rays,Ultraviolet rays are harmful for the human body.

• Infrared rays are also dangerous, due to eye safety regulation, and can only be used with low

power.

• Radio waves are expensive and they are less secure.

• Hence we are left with only the VISIBLE - LIGHT SPECTRUM which is not harmful for humans .

CONSTRUCTION and WORKING OF Li-Fi

• Li-Fi is implemented using white LED light bulbs at downlink transmitter.

• By fast variations of the current, optical output can be made to vary at extremely

high speeds.

• An overhead lamp fitted with an LED with signal processing technology streams

data embedded in its beam at ultra high speeds to the photodiodes.

• A receiver dongle then converts the tiny changes in amplitude into an electrical

signal, which is then converted back into a data stream & transmitted to a computer

or mobile device.

Sl.No Parameters Light Fidelity Wireless Fidelity

1 Speed for data transfer Faster transfer speed (>1 Gbps) Data Transfer speed (150 Mbps)

2 Medium through which

data transfers occurs

Used Light as a carrier Used Radio spectrum

3 Spectrum Range Visible light spectrum has 10,000 time

broad spectrum in comparison to radio

frequency

Radio frequency spectrum range is

less than visible light spectrum.

4 Cost Cheaper than Wi-Fi because free band

doesn’t need license and it use light.

Expensive in comparison to Li-Fi

because its uses radio spectrum.

5 Network topology Point to point Point to point

6 Operating frequency Hundreds of Tera Hz (THz) 2.4 GHz

COMPARISON BETWEEN LI-FI AND WI-FI

FUTURE APPLICATIONS

In vehicles and traffic lights, reducing accidents and traffic

congestion

Street lamps(as free access points)

In Airplanes' And Underwater

Hospitals

Availability Efficiency Harmless

High Security

Ease of use Fast Data Transfer

Low Cost

ADVANTAGES

DISADVANTAGES

•Light can't pass through objects.

•A major challenge facing Li-Fi is how the receiving

device will transmit back to transmitter.

•High installation cost of the VLC systems

•Interferences from external light sources like

sun , light , normal bulbs , opaque materials .

CONCLUSION

• The possibilities are numerous and can be explored further.

• In spite of disadvantages if this technology can be put into

practical use, every bulb can be used something like a Wi-Fi

hotspot to transmit wireless data and we will proceed toward the

cleaner, greener, safer and brighter future.

• Jyoti Rani1, Prerna Chauhan2, Ritika ripathi3,1Student,

,2Student,ad ,3Assistant Professor, ECE, Dep't. " Li-Fi (Light

Fidelity)-The future technology In Wireless communication"

ISSN 0973-4562 Vol.7 No.11 (2012)

• Shailander kaushik, System Analytic,Nuclear Software export

Ltd, "An overview of technical aspects for wifi networks

technology " ,ISSN-2277-1956.

• Visible Light Communications Consortium,www.vlcc.net, 2008

REFERENCES