Li- Fi (Light – Fidelity)

Contents - INTRODUCTION - HOW LI-FI IS DIFFERENT ? - HISTORY OF LI-FI - LI-FI CONSTRUCTION - WHY LI-FI COMES ? - HOW LI-FI WORKS ? - LI-FI VS WI-FI - FEATURES - ADVANTAGES - DIADVANTAGES - APPLICATIONS - FUTURE SCOPE - CONCLUSION

Introduction Li-Fi means “LIGHT FIDELITY” Li-Fi is fast and cheap optical version of wi-Fi. Li-Fi is a technology that uses the LIGHT EMITTING DIODES (LED) to transmit the data wirelessly . Li-Fi based on VISIBLE LIGHT COMMUNICATION (VLC). VLC is a data communication medium, which uses the visible light between 400 THz (780 nm) and 800 THz (375 nm) as optical carrier for data transmission.

How Li-Fi Is Different ? - Li-Fi technology is based on LEDs for the transfer of data. - The transfer of the data can be with the help of all kind of light i.e., Light may be Invisible, Ultraviolet or Visible part of spectrum. - The speed of the internet is incredibly high and the user everything in just a few minutes.

History of Li-Fi This technology was invented by German Physicist “HARALD HASS”, from the university of Edinburgh, U.K. - He demonstrated it in the year 2012. - But, the technology was truly began during the 1990’s in countries like Germany, Korea & Japan. - where they discovered LED’s could be retrofitted to send information UNIVERSITY OF EDINBURGH :-

Li-Fi Construction The Li-Fi product consists of three primary sub- assemblies:- Emitter (including bulb) RF Driver. Power supply

Function of Bulb Assembly At the heart of LIFI is the bulb sub-assembly where a sealed bulb is embedded in a dielectric material. The dielectric material serves two purposes: 1) waveguide 2) Electric field

RF Drive Power amplifier (PA) assembly that uses an LDMOS device. Converts electrical energy into RF power. The PA is designed for ruggedness and efficiency. The RF driver also contains controls circuit for digital and analog lighting controls.

A Typical Li-Fi Scenario

Capacity Efficiency Security Why Li-Fi comes ? - Due to Issues regarding with Radio frequency Spectrum - Electromagnetic spectrum - These are - Capacity Availability Efficiency Security

Radio Spectrum Issues Security Capacity Less secure(passes through the walls) Capacity Radio waves. Cost and Expensive. Less Bandwidth compared to other spectrums. Insufficient spectrum for increasing data. Efficiency Millions of base stations consume huge amount of energy for 1.) Transmitting the radio waves 2.) To cool the base station cabins 5% Efficiency Availability Available within the range of Base stations. Limited availability. Unavailable in aircrafts.

Electromagnetic Spectrum

Why Only VLC ? Gama rays cant be used as they could be dangerous. Radio Waves Infrared Rays Visible Rays Ultraviolet Rays X- Rays Gama Rays Gama rays cant be used as they could be dangerous. X-rays have similar health issues. Ultraviolet light is good for place without people, but other wise dangerous for the human body. Infrared, due to eye safety regulation, can only be used with low power. HENCE WE LEFT WITH THE ONLY THE VISIBLE - LIGHT SPECTRUM.

RADIO WAVES FOR WIRELESS WHAT USES CAN REPLACE RADIO WAVES FOR WIRELESS COMMUNICATION ?

THROUGH LI-FI - By the use of li-fi we can replace radio waves for wireless communication

How Li-Fi Works ? Procedure is very simple, if the LED is on , then your device transmit a digit ‘1’ & if it is off, then your device transmit a digit ‘0’. The LED can be switched on & off very quickly, which gives nice opportunities for transmitting data. Hence, all that required is some LEDS & a controller that code data into those LEDS.

Comparison Between Li-Fi vs. Wi-Fi

Features of Li-Fi CAPACITY - 10,000 Times more spectrum then RW. - Light boxes are already present, so infrastructure is available already and installed . EFFICIENCY - Highly efficient because LED consume less energy. AVAILABLITY - Light is present every where. - Data is present where light is present. SECURITY - Light waves does not penetrate through walls. - Hence they can not be INTERCEPTED.

Advantages of Li-Fi It is impossible to achieve more than 10Gbps, theoretically allowing a high-definition film to be downloaded in 30 sec. Mostly powered by LEDs so it is cost efficient Transmission of data is fast and easy. MAPS

Disadvantages of Li-Fi Presence of light is essential There should be line of sight Works better with fluorescent light and LEDs but very low efficiency with bulbs.

Street and traffic light Applications of Li-Fi Street and traffic light

Under water scenarios

Airplane scenarios

In RF restricted environment

Future Scope This research report categories the global VLC technology market based on component, application and geography. Li-fi uses light emitting diodes (LEDs) which are rapidly gaining in popularity for standards light bulbs and other domestic and commercial purposes . They are expected to be ubiquitous in 20 years. Still under research :- What will be effect of interference from external light sources like sun light and normal bulbs ? What about the limited bandwidth of existing copper cable used for electrical connection.

Future Scope Where do the connections uplink, how serious are the modifications needed to the power grid. How will other devices React if you Inject a high frequency in to Main ?

Conclusion The possibilities are numerous and can be explored further. If this technology can be put into practical use , every bulb can be used something like a Wi-Fi hotspots to transmit wireless data.

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