B.T. INSTITUTE OF

RESEARCH &

TECHNOLOGY

LI-FI

TECHNOLOGY

CONTENTS

• INTRODUCTION TO LI-FI

• HOW DOES IT WORKS?

• COMPARISON WITH WI-FI

• 4 ISSUES WITH RADIOWAVE

• ALTERNATIVE FOR RADIO WAVE

• APPLICATION OF LI-FI

• LIMITATIONS OF LI-FI

• IS IT A PROVEN TECHNOLOGY?

INTRODUCTION TO LI-FI• LI-FI IS A TECHNOLOGY THAT USES THE LIGHT

EMITTING DIODES TO TRANSMIT THE DATA WIRELESSLY.

• LI-FI IS FAST AND CHEAP OPTICAL VERSION OF WI-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

WHO INVENTED IT ?

• THIS TECHNOLOGY WASINVENTED BY GERMAN

PHYSICIST HARALD HAAS , FROMTHE UNIVERSITY OF EDINBURGH ,U.K .

• HE DEMONSTRATED IT IN THE YEAR2011 IN TED TALK SHOW.

HOW IT WORKS• LAMP FITTED WITH LED

WITH SIGNAL PROCESSING TECHNOLOGY STREAMS DATA IN ITS BEAM AT ULTRA HIGH-SPEED TO THE PHOTO DETECTOR

• RECEIVER DONGLE CONVERTS TINY CHANGES IN AMPLITUDE TO ELECTRICAL SIGNAL WHICH IS CONVERTED BACK TO DATA STREAM AND TRANSMITTED TO COMPUTER OR MOBILE DEVICES

AT HOME / OFFICE

IN TRAFFIC CONTROL

LIFI VS WIFI

DATA TRANSFER SPEED

• Li-Fi has a High speed data transfer rate over 1Gbps.

• Wi-Fi has a data transfer rate of maximum 54Mbps.

• LI-FI USES THE VISBLE LIGHT PORTION OF THE EM SPECTRUM

• WIFI USE THE RADIOWAVE PORTION OF THE EM SPECTRUM

PART OF EM SPECTRUM THEY USE

ISSUES WITH RADIO WAVE CAPACITY

• WITH THE ADVENT OF NEW TECHNOLOGIES LIKE 3G, 4G WE ARE RUNNING OUT OF SPECTRUM.

• THAT’S WHY RADIO WAVES ARE NOW BECOMING EXPENSIVE.

EFFICIENCY

• THERE ARE 1.4 MILLIONS CELLULAR RADIO BASE STATIONS .

• MOST OF THE ENERGY IS NOT USED FOR TRANSMISSION BUT RATHER FOR COOLING DOWN THE BASE STATION.

SECURITY

• RADIO WAVES CAN PENETRATE THROUGH WALLS AND HENCE CAN BE INTERCEPTED.

• ANYONE WITH KNOWLEDGE AND BAD INTENTION CAN MISUSE IT.

AVALILABLITY

• WE HAVE TO SWITCH OFF MOBILES IN AIRCRAFTS.

• IT IS ALSO NOT ADVISABLE TO USE MOBILES AT PETROL PUMPS.

ALTERNATIVE TO RADIO WAVE IN EM SPECTRUM

• Gamma rays are simply dangerous and thus can’t beused for our purpose of communication.

• X-rays are good in hospitals and can’t be usedeither.

• Ultra violet rays are sometimes good for our skinbut for long duration it is dangerous.

• Infrared rays are bad for our eyes and are thereforeused at low power levels.

• So we are now left with Visible Rays.

Radio-

Waves

Infra-

Waves

Visible

Rays

Ultra-

VioletX-rays

Gamma

Rays

OVERCOMING THE FOUR ISSUES WITH RW IN LI-FI

CAPACITY• 10000 TIMES MORE SPECTRUM THAN RW.EFFICIENCY• HIGHLY EFFICIENT BECAUSE LED CONSUMES LESS

ENERGY.AVAILABLITY• LIGHT IS PRESENT EVERYWHERE.• DATA IS PRESENT WHERE LIGHT IS PRESENT.

SECURITY• LIGHT WAVES DOESNOT PENETRATE THROUGH WALLS.• HENCE THEY CAN’T BE INTERCEPTED.

• You Can Use Li-Fi In Hospitals And Aircrafts Also.

• Cheaper Then Wi-Fi , Since Visible Light Spectrum Is AFree Spectrum Band.

• Thousands And Millions Of Street Lamps Can BeConverted To Li-fi Spots.

• Light Is Readily Available In Every Part Of The World.

• This Makes It Easy For People In Airplanes To Work OnThe Internet.

ADVANTAGES OF LI-FI

• Visible light cannot penetrate through solid objects

• Interference with other electromagnetic waves makes

the transmitting data to distort

• Light cannot approach the range and penetration ofradio waves

• High installation cost of the VLC systems

• A major challenge facing Li-Fi is how the receivingdevice will transmit back to transmitter.

LIMITATIONS OF LI-FI

IS THIS A PROVEN TECHNOLOGY ?

• YES THIS ALREADY PROVEN.

• HARALD HAAS DEMONSTRATED HIS INVENTION USING AN ORDINARY TABLE LAMP THAT SUCCESSFULLY TRANSMITTED DATA AT SPEEDS EXCEEDING 10Mbps USING LIGHT WAVES FORM LED LIGHT BULBS TO A COMPUTER LOCATED BELOW THE LAMP.

• TO PROVE THAT THE LIGHT WAS THE SOURCE OF THE DATA STREAM HE PERIODICALLY BLOCKED THE BEAM OF LIGHT , CAUSING THE CONNECTION TO DROP.