LI-FI TECHNOLOGY

ONKAR BHUJBALRoll No-27

Div –TE(A)

S.R. PAWARA

CONTENTS

INTRODUCTION

HISTORY

PRESENT SCENARIO

ISSUES REGARDING RADIO SPECTRUM

VISIBLE LIGHT SPECTRUM

HOW LIFI WORKS

CONSTRUCTION OF LIFI

COMPARISON OF LIFI WITH WIFI

APPLICATIONS

LIMITATIONS

CONCLUSION

REFERENCES

INTRODUCTION

Li-fi basically known as “LIGHT FEDILITY”

The basic ideology behind this technology is that the data can be transmitted

through LED light whose intensity varies even faster than the human eye.

Li-Fi is the term some have used to label the fast and cheap wireless-

communication system

As there are more and more devices coming up day-by-day the signals are

being clogged up due to heavy traffic, there a need for an error free transmission

technology.

history

The technology truly began during the 1990's in countries like

Germany, Korea, and Japan where they discovered LED's could be

added to send information.

At TED Global Talk, Haas demonstrated a data rate of transmission

of around 10Mbps.

German scientists succeeded in creating an800Mbps (Megabits per

second) capable wireless network by using nothing more than

normal red, blue, green and yellow LEDS.

In October 2011 a number of companies and industries formed the

Li-Fi Consortium, to promote high-speed optical wireless system to

enhance the limited bandwidth provided by radio-based wireless

spectrum available.

PRESENT SCENARIO

1.4 Million Base Stations 5 Billion Devices

PRESENT SCENARIO

Radio Spectrum is congested but the demand for wireless data

double each year .Every thing, it seems want to use wireless

data but the capacity is drying up.

So what can carry this excess demand in the future .

Capacity :

We transmit wireless data through radio waves.

Radio waves are limited.

Radio waves are scar and expensive.

We only have a certain range of it.

With the advent of the generation technology as of like of 2.5G,3G,4G and so on we are running out of spectrum.

Efficiency :

There are 1.4 million cellular radio base stations

They consume massive amount of energy

Most of this energy is not use for transmission but for cooling down the base stations

Efficiency of such a base station is only 5% and that raise a very big problem

Availability :

Availability of radio waves causes another concern.

We have to switch off our mobiles in airplanes.

It is not advisable to use mobiles at places like petrochemical plants ,hospitals

petrol pumps.

Security :

Radio waves penetrates through walls

They can be intercepted

If someone has a knowledge and bad intentions then he may misuse it

.

Radio Waves

Infrared Rays

Visible Rays

Ultra Violet Rays

X-RaysGamma

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.

Radio waves are limited bandwidth, expensive and less secure.

FIG-Electromagnetic Spectrum

How LI-FI Works ?

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 the digital

data in form of light.

The LED lamp will hold a microchip that will do the job of

processing the data.

A light sensitive device (photo detector) receives the signal and

converts it back into original data.

Figure- Architecture Of Li-Fi

An RF (radio-frequency) signal is generated by the solid-state

PA and is guided into an electric field about the bulb.

The PCB controls the electrical inputs and outputs of the lamp

and houses the microcontroller used to manage different lamp

functions.

The high concentration of energy in the electric field vaporizes

the contents of the bulb to a plasma state at the bulb’s centre ;

this controlled plasma generates an intense source of light

CONSTRUCTION

The LIFI product consists of 4 primary sub-assemblies:

• BULB

• RF power amplifier circuit (PA)

• Printed circuit board (PCB)

• Enclosure

APPLICATIONS OF LIFI

There are millions of street lamps deployed around the world.

Streets lamps can be transferred to lifi lamps to transfer data.

Each of these street lamps could be a free access point.

PUBLIC INTERNET

HOTSPOTS

TRAFFIC LIGHTS

Traffic lights can communicate to the car and

with each other.

Cars have LED-based headlights, and cars

can communicate with each other and prevent

accidents in by exchanging information.

ON OCEAN BEDS

Li-Fi can even work underwater were Wi-Fi fails

completely, thereby throwing open endless

opportunities for military/navigation operations.

Visible Light is more safe than RF.

Hence it can be used in places such as

petrochemical plants, Hospitals, Airlines

where RF is restricted.

SAFE ENVIRONMENT

High installation cost of the VLC systems.

A major challenge facing Li-Fi is how the receiving device will transmit

back to transmitter.

Light can't pass through objects.

Requires line of sight to transmit data.

LIMITATIONS

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.

REFERENCES

Wikipedia

http://lificonsortium.org/

http://gimt.edu.in/clientFiles/FILE_REPO/2012/NOV/23/1353645362

045/69.pdf

https://www.youtube.com/watch?v=WRG9iXZbuAc