TECHNICAL SEMINAR ONLI-FI(LIGHT FIDELITY)

By

G.N.V.S. SAI KIRAN(10AG1A0441)

Under the Guidance Of:

Asst Prof. Y.V.S. DURGA PRASAD

Present Scenario Issues regarding Radio spectrumHistoryDemonstration IntroductionWorkingConstructionApplicationsAdvantagesChallengesConclusion

CONTENTS

•72 hours of video are uploaded to YouTube every minute

•25% of global YouTube views come from mobile devices

•Internet video traffic is growing at 48% CAGR

•Mobile phones transmit 600TB of data every month

•Wireless communication has become an utility like electricity and water

PRESENT SCENARIO

LEADING TO RF SPECTRUM SHORTAGE

ISSUES REGARDING RADIO SPECTRUM

CAPACITY: With the increasing number of mobile subscribers

the spectrum is getting congested.EFFICIENCY: The data speeds can only reach up to a few hundreds of megabits per second.AVAILABILITY: The availability of the radio waves is yet another

major issue.SECURITY: These radio waves can easily penetrate through

the walls, thus letting anonymous users to use the network.

HOW TO FIX THE PROBLEM?

HISTORY The technology truly began during

the 1990's in countries like Germany, Korea, and Japan where they discovered LED's could be retrofitted to send information.

A German physicist Dr. Harald Haas, has started working on transmission of data using visible light back in 2004.

In the year 2011 he first introduced to the world this new technology,LI-FI in the TED talk show.

DEMONSTRATION

INTRODUCTION

Li-Fi is transmission of data through illumination sending data through a LED light bulb that switches faster than human eye can follow.

This invisible on-off activity enables a kind of data transmission using binary codes, switching on LED is a logical ‘1’, switching it off is a logical ‘0’.

Li-Fi is a VLC, visible light communication, which uses the visible light between 400 THz (780 nm) and 800 THz (375 nm) as optical carrier for data transmission.

WHY ONLY VLC ?

Gamma rays are dangerous and thus can’t be used for our purpose of communication.

X-rays are good in hospitals and can’t be used either. Ultra violet rays are sometimes good for our skin but

for long duration it is dangerous. Infrared rays are bad for our eyes and are therefore

used at low power levels. We have already seen the short comings of radio

waves. So we are left with Visible light.

Radio-Waves

Infra-Waves

VisibleRays

Ultra-Violet X-rays Gamma

Rays

WORKING

• On one end all the data on the internet will be streamed to a lamp driver.• When the LED is turned on the microchip converts this digital data in the form of light.• On the other end this light is detected by photo sensitive devices.• Next this light is amplified and processed and then fed to the device.

CONSTRUCTION

The Li-Fi chip consists of 4 primary sub-assemblies:• Bulb• RF power amplifier circuit (PA)• Printed circuit board (PCB)• Enclosure The PCB controls the electrical inputs and

outputs of the lamp. An RF (radio-frequency) signal is generated by

the PA is guided into an electric field about the bulb vaporizes the contents of the bulb to a plasma state and generates an intense source of light.

PROTOTYPE OF LI-FI

INTRINSICALLY SAFE ENVIRONMENT

Applications

IN VEHICLES AND TRAFFIC LIGHTS

PUBLIC INTERNET HOTSPOTS

IN AIRCRAFT CABINS

Hospitals(In few medical instruments)

ADVANTAGES Visible light spectrum is 10000 times more

compared to radio wave spectrum The data transmission can reach up to gigabits

per second thus providing very rich data streaming.

The sources can be used as normal lights when there is no data transmission

• There should be line of sight between sender and receiver

• Visible light cannot penetrate through solid objects

• High installation cost of the VLC systems

• Interferences from external light sources like sun light, normal bulbs, in the path of transmission will cause data to distort

CHALLENGES

CONCLUSION If this technology can be put into practical use,

every light source can be used like a Wi-Fi hotspot to transmit data.

Li-Fi cannot wipe off the need of Wi-Fi. Li-Fi is complementary.