ACKNOWLEDGEMENT

I thank my seminar guide Mrs. Rahul mathur for his proper guidance, and valuable

suggestions. I am indebted to Mrs. Surendra bohra, the HOD, ECE department & other faculty

members for giving me an opportunity to learn and present the seminar. If not for the above

mentioned people my seminar would never have been completed successfully.

I once again extend my sincere thanks to all of them.

Vikash jakhar

(student of electronics & comm.branch).

1

INDEX OF REPORT

Sr.no Objectives Names

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

Abstract of Li-Fi technology ……………………………………………….01

Introduction to Li-Fi technology …………………………………………….02

Genesis of LI-FI technology …………………………………………………..05

How Li-Fi Works? ……………………………………………………….07

Comprision Between Li-Fi & Wi-Fi ………………………………………..11

How LI-FI Light Sources Work? …………………………………………….13

Function Of The Bulb ? ……………………………………………………14

Application area of li-fi technology… ……………………………………….17

Conclusion ………...…………………………………………………….31

References …….………………………………………………………..32

2

Abstract of Li-Fi Technology:-

Whether you’re using wireless internet in a coffee shop, stealing it from the guy next

door, or competing for bandwidth at a conference, you’ve probably gotten frustrated at the slow

speeds you face when more than one device is tapped into the network. As more and more

people and their many devices access wireless internet, clogged airwaves are going to make it

increasingly difficult to latch onto a reliable signal. But radio waves are just one part of the

spectrum that can carry our data. What if we could use other waves to surf the internet? One

German physicist,DR. Harald Haas, has come up with a solution he calls “Data Through

Illumination”—taking the fiber out of fiber optics by sending data through an LED light bulb

that varies in intensity faster than the human eye can follow. It’s the same idea behind infrared

remote controls, but far more powerful. Haas says his invention, which he calls D-Light, can

produce data rates faster than 10 megabits per second, which is speedier than your average

broadband connection. He envisions a future where data for laptops, smartphones, and tablets is

transmitted through the light in a room. And security would be a snap—if you can’t see the light,

you can’t access the data.

Li-Fi is a VLC, visible light communication, technology developed by a team of

scientists including Dr Gordon Povey, Prof. Harald Haas and Dr Mostafa Afgani at the

University of Edinburgh. The term Li-Fi was coined by Prof. Haas when he amazed people by

streaming high-definition video from a standard LED lamp, at TED Global in July 2011. Li-Fi is

now part of the Visible Light Communications (VLC) PAN IEEE 802.15.7 standard. “Li-Fi is

typically implemented using white LED light bulbs. These devices are normally used for

illumination by applying a constant current through the LED. However, by fast and subtle

variations of the current, the optical output can be made to vary at extremely high speeds.

3

Unseen by the human eye, this variation is used to carry high-speed data,” says Dr Povey, ,

Product Manager of the University of Edinburgh's Li-Fi Program ‘D-Light Project’.

Introduction of Li-Fi Technology:-

In simple terms, Li-Fi can be thought of as a light-based Wi-Fi. That is, it uses light

instead of radio waves to transmit information. And instead of Wi-Fi modems, Li-Fi would use

transceiver-fitted LED lamps that can light a room as well as transmit and receive information.

Since simple light bulbs are used, there can technically be any number of access points.

This technology uses a part of the electromagnetic spectrum that is still not greatly

utilized- The Visible Spectrum. Light is in fact very much part of our lives for millions and

millions of years and does not have any major ill effect. Moreover there is 10,000 times more

space available in this spectrum and just counting on the bulbs in use, it also multiplies to 10,000

times more availability as an infrastructure, globally.

It is possible to encode data in the light by varying the rate at which the LEDs flicker on

and off to give different strings of 1s and 0s. The LED intensity is modulated so rapidly that

human eyes cannot notice, so the output appears constant.

More sophisticated techniques could dramatically increase VLC data rates. Teams at the

University of Oxford and the University of Edinburgh are focusing on parallel data transmission

using arrays of LEDs, where each LED transmits a different data stream. Other groups are using

mixtures of red, green and blue LEDs to alter the light's frequency, with each frequency

encoding a different data channel.

Li-Fi, as it has been dubbed, has already achieved blisteringly high speeds in the lab.

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. Haas has set up a spin-off firm to

sell a consumer VLC transmitter that is due for launch next year. It is capable of transmitting

data at 100 MB/s - faster than most UK broadband connections.

4

LiFi is transmission of data through illumination by taking the fiber out of fiber optics by

sending data through a LED light bulb that varies in intensity faster than the human eye can

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

system, which is the optical version of Wi-Fi. The term was first used in this context byHarald

Haas in his TED Global talk on Visible LightCommunication. “At the heart of this technology is

a new generation of high brightness light-emitting diodes”, says Harald Haas from the University

of Edinburgh, UK,”Verysimply, if the LED is on, you transmit a digital 1, if it’s offyou transmit

a 0,”Haas says, “They can be switched on and offvery quickly, which gives nice opportunities

for transmitteddata.”It is possible to encode data in the light by varying therate at which the

LEDs flicker on and off to give different strings of 1s and 0s.The LED intensity is modulated so

rapidly that human eye cannot notice, so the output appears constant. More sophisticated

techniques could dramatically increase VLC data rate. Terms at the University of Oxford and the

University of Edingburgh are focusing on parallel data transmission using array of LEDs, where

each LED transmits a different data stream. Other group are using mixtures of red,

green and blue LEDs to alter the light frequency encoding a different data channel.Li-Fi, as it has

been dubbed, has already achieved blisteringly high speed in the lab. 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. The technology was demonstrated at the 2012 Consumer

Electronics Show in Las Vegas using a pair of

Casio smart phones to exchange data using light of varying intensity given off from their screens,

detectable at a distance of up to ten metres.

5

Fig.1 Li-Fi enviorment

In October 2011 a number of companies and industry groups formed the Li-Fi Consortium, to

promote high-speed optical wireless systems and to overcome the limited amount of

radiobasedwireless spectrum available by exploiting a completely different part of the

electromagnetic spectrum. The consortium believes it is possible to achieve more than 10 Gbps,

theoretically allowing a high-definition film to be downloaded

in 30 seconds.

Li-Fi: A New Paradigm in Wireless Communication

Most of us are familiar with Wi-Fi (Wireless Fidelity), which uses 2.4-5GHz RF to deliver

wireless Internet access around our homes, schools, offices and in public places. We have

become quite dependent upon this nearly ubiquitous service. But like most technologies, it has its

limitations.While Wi-Fi can cover an entire house, its bandwidth is typically limited to 50-100

6

megabits per second (Mbps) today using the IEEE802.11n standard. This is a good match to the

speed of most current Internet services, but insufficient for moving large data files like HDTV

movies, music libraries and video games.The more we become dependent upon ‘the cloud’ or

our own ‘media servers’ to store all of our files, including movies, music, pictures and games,

the more we will want bandwidth and speed. Therefore RF-based technologies such as today’s

Wi-Fi are not the optimal way. In addition, Wi-Fi may not be the most efficient way to provide

new desired capabilities such as precision indoor positioning and gesture recognition.Optical

wireless technologies, sometimes called visible light communication (VLC), and more recently

referred to as Li-Fi (Light Fidelity), on the other hand, offer an entirely new paradigm in wireless

technologies in terms of communication speed, flexibility and usability.

Fig.

1: Li-Fi as a superset of different optical wireless technologies involving communication,

positioning, natural user interfaces and many more

Genesis of LI-FI:

Harald Haas, a professor at the University of Edinburgh who began his research in the

field in 2004, gave a debut demonstration of what he called a Li-Fi prototype at the TEDGlobal

7

conference in Edinburgh on 12th July 2011. He used a table lamp with an LED bulb to transmit a

video of blooming flowers that was then projected onto a screen behind him. During the event he

periodically blocked the light from lamp to prove that the lamp was indeed the source of

incoming data. At TEDGlobal, Haas demonstrated a data rate of transmission of around 10Mbps

-- comparable to a fairly good UK broadband connection. Two months later he achieved

123Mbps.

 

Back in 2011 German scientists succeeded in creating an800Mbps (Megabits per second)

capable wireless network by using nothing more than normal red, blue, green and

white LED light bulbs (here), thus the idea has been around for awhile and various other global

teams are also exploring the possibilities.

8

How Li-Fi Works?

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

These devices are normally used for illumination only by applying a constant current. However,

by fast and subtle variations of the current, the optical output can be made to vary at extremely

high speeds. This very property of optical current is used in Li-Fi setup. The operational

procedure is very simple-, if the LED is on, you transmit a digital 1, if it’s off you transmit a 0.

The LEDs can be switched on and off very quickly, which gives nice opportunities for

transmitting data. Hence all that is required is some LEDs and a controller that code data into

those LEDs. All one has to do is to vary the rate at which the LED’s flicker depending upon the

data we want to encode. Further enhancements can be made in this method, like using an array of

LEDs for parallel data transmission, or using mixtures of red, green and blue LEDs to alter the

light’s frequency with each frequency encoding a different data channel. Such advancements

promise a theoretical speed of 10 Gbps – meaning one can download a full high-definition film

in just 30 seconds.

9

To further get a grasp of Li-Fi consider an IR remote.(fig 3.3). It sends a single data

stream of bits at the rate of 10,000-20,000 bps. Now replace the IR LED with a Light Box

containing a large LED array. This system, fig 3.4, is capable of sending thousands of such

streams at very fast rate.

10

Light is inherently safe and can be used in places where radio frequency communication

is often deemed problematic, such as in aircraft cabins or hospitals. So visible light

communication not only has the potential to solve the problem of lack of spectrum space, but can

also enable novel application. The visible light spectrum is unused, it's not regulated, and can be

used for communication at very high speeds.

This brilliant idea was first showcased by Harald Haas fromUniversity of Edinburgh, UK,

in his TED Global talk on VLC.He explained,” Very simple, if the LED is on, you transmit

adigital 1, if it’s off you transmit a 0. The LEDs can beswitched on and off very quickly, which

gives nice

opportunities for transmitting data.” So what you require at allare some LEDs and a controller

that code data into thoseLEDs. We have to just vary the rate at which the LED’sflicker

depending upon the data we want to encode. Furtherenhancements can be made in this method,

like using an arrayof LEDs for parallel data transmission, or using mixtures ofred, green and blue

LEDs to alter the light’s frequency witheach frequency encoding a different data channel.

Suchadvancements promise a theoretical speed of 10 Gbps –meaning you can download a full

high-definition film in just30 seconds. Simply awesome! But blazingly fast data ratesand

11

depleting bandwidths worldwide are not the only reasonsthat give this technology an upper hand.

Since Li-Fi uses justthe light, it can be used safely in aircrafts and hospitals that areprone to

interference from radio waves. This can even workunderwater where Wi-Fi fails completely,

thereby throwingopen endless opportunities for military operations

Imagine only needing to hover under a street lamp to getpublic internet access, or

downloading a movie from the lampon your desk. There's a new technology on the block which

could, quite literally as well as metaphorically, 'throw light on'how to meet the ever-increasing

demand for high-speedwireless connectivity. Radio waves are replaced by lightwaves in a new

method of data transmission which is beingcalled Li-Fi.Light-emitting diodes can be switched on

and offfaster than the human eye can detect, causing the light sourceto appear to be on

continuously. A flickering light can beincredibly annoying, but has turned out to have its

upside,being precisely what makes it possible to use light for wirelessdata transmission. Light-

emitting diodes (commonly referredto as LEDs and found in traffic and street lights, car

brakelights, remote control units and countless other applications)can be switched on and off

faster than the human eye candetect, causing the light source to appear to be oncontinuously,

even though it is in fact 'flickering'. Thisinvisible on-off activity enables a kind of data

transmissionusing binary codes: switching on an LED is a logical '1',switching it off is a logical

'0'. Information can therefore beencoded in the light by varying the rate at which the LEDsflicker

on and off to give different strings of 1s and 0s. Thismethod of using rapid pulses of light to

transmit informationwirelessly is technically referred to as Visible LightCommunication (VLC),

though it’s potential to compete withconventional Wi-Fi has inspired the popular

characterization Li-Fi.

Visible light communication (VLC)-“A potential solutionto the global

wireless spectrum shortage”

12

LiFi (Light Fidelity) is a fast and cheap optical version of Wi-Fi, the technology of which

is based on Visible LightCommunication (VLC).VLC is a data communication medium, which

uses visible light between 400 THz (780 nm)and 800 THz (375 nm) as optical carrier for data

transmissionand illumination. It uses fast pulses of light to transmitinformation wirelessly. The

main components of thiscommunication system are 1) a high brightness white LED,Which acts

as a communication source and 2) a siliconphotodiode which shows good response to visible

wavelengthregion serving as the receiving element? LED can be switchedon and off to generate

digital strings of 1s and 0s. Data can beencoded in the light to generate a new data stream by

varyingthe flickering rate of the LED. To be clearer, by modulatingthe LED light with the data

signal, the LED illumination canbe used as a communication source. As the flickering rate is so

fast, the LED output appears constant to the human eye. Adata rate of greater than 100 Mbps is

possible by using highspeed LEDs with appropriate multiplexing techniques. VLC. data rate can

be increased by parallel data transmission usingLED arrays where each LED transmits a

different data stream.There are reasons to prefer LED as the light source in VLCwhile a lot of

other illumination devices like fluorescent lamp,incandescent bulb etc. are available.

COMPARISION BETWEEN Li-Fi & Wi-Fi

LI-FI is a term of one used to describe visible lightcommunication technology applied to

high speed wirelesscommunication. It acquired this name due to the similarity toWI-FI, only

using light instead of radio.WI-FI is great forgeneral wireless coverage within buildings, and li-fi

is idealfor high density wireless data coverage in confined area andfor relieving radio

interference issues, so the two technologiescan be considered complimentary.

13

Table 1.Comparison between current and future wirelesstechnology

The table also contains the current wireless technologies thatcan be used for transferring

data between devices today, i.e.Wi-Fi, Bluetooth and IrDA. Only Wi-Fi currently offers veryhigh

data rates. The IEEE 802.11.n in most implementationsprovides up to 150Mbit/s (in theory the

standard can go to600Mbit/s) although in practice you receive considerably lessthan this. Note

that one out of three of these is an opticaltechnology.

14

Li-Fi technology is based on LEDs for the transfer of data.The transfer of the data can be

with the help of all kinds oflight, no matter the part of the spectrum that they belong. Thatis, the

light can belong to the invisible, ultraviolet or thevisible part of the spectrum. Also, the speed of

the internet isincredibly high and you can download movies, games, musicetc in just a few

minutes with the help of this technology.Also, the technology removes limitations that have been

puton the user by the Wi-Fi. You no more need to be in a regionthat is Wi-Fi enabled to have

access to the internet. You cansimply stand under any form of light and surf the internet asthe

connection is made in case of any light presence. Therecannot be anything better than this

technology.

Technology Brief:-

How LI-FI Light Sources Work:-

LI-FI is a new class of high intensity light source of solid state design bringing clean lighting

solutions to general and specialty lighting. With energy efficiency, long useful lifetime, full

spectrum and dimming, LI-FI lighting applications work better compared to conventional

approaches. This technology brief describes the general construction of LI-FI lighting systems

and the basic technology building blocks behind their function.

The LIFI™ product 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 and houses the microcontroller

used to manage different lamp functions.

An RF (radio-frequency) signal is generated by the solid-state PA and is guided into an electric

field about the bulb. The high concentration of energy in the electric field vaporizes the contents

15

of the bulb to a plasma state at the bulb’s center; this controlled plasma generates an intense

source of light.

All of these subassemblies are contained in an aluminum enclosure

FUNCTION OF THE BULB:-

At the heart of LIFI™ is the bulb sub-assembly where a sealed bulb is embedded in a dielectric

material. This design is more reliable than conventional light sources that insert degradable

electrodes into the bulb. The dielectric material serves two purposes; first as a waveguide for the

RF energy transmitted by the PA and second as an electric field concentrator that focuses energy

in the bulb. The energy from the electric field rapidly heats the material in the bulb to a plasma

state that emits light of high intensity and full spectrum.

The design and construction of the LIFI™ light source enable efficiency, long stable life, full

spectrum intensity that is digitally controlled and easy to use.

16

17

Fig :- representing the data transfer using light

Application area of li-fi technology

Airways:-

Whenever we travel through airways we face the problem in

communication media ,because the whole airways communication

are performed on the basis of radio waves.

To overcomes this drawback on radioways ,li-fi is introduce.

Green information technology:-

Green information technology means that unlike radiowaves and other

communication waves affects on the birds , human bodys etc. Li-Fi never gives such

side effects on any living thing..

Free From Frequency Bandwidth Problem:-

Li-fi is an communication media in the form of light ,so no matter about

the frequency bandwidth problem . It does not require the any bandwidth

spectrum i.e. we don’t need to pay any amount for communication and licence.

Increase Communication Safety:-

Due to visual light communication , the node or any terminal attach to our

network is visible to the host of network .

Multi User Communication:-

Li-Fi supports the broadcasting of network , it helps to share multiple

thing at a single instance called broadcasting.

18

Lightings Points Used as Hotspot:-

Any lightings device is performed as a hotspot it means that the light

device like car lights, ceiling lights , street lamps etc area able to spread internet

connectivity using visual light communication. Which helps us to low cost

architecture for hotspot.

Hotspot is an limited region in which some amount of device can

access the internet connectivity .

4.1 You Might Just Live Longer

For a long time, medical technology has lagged behind the restof the wireless world.

Operating rooms do not allow Wi-Fiover radiation concerns, and there is also that whole lack

ofdedicated spectrum. While Wi-Fi is in place in many hospitals,interference from cell phones

and computers can block signalsfrom monitoring equipment. Li-Fi solves both problems: lights

are not only allowed in operating rooms, but tend to be themost glaring (pun intended) fixtures in

the room. And, as Haasmentions in his TED Talk, Li-Fi has 10,000 times thespectrum of Wi-Fi,

so maybe we can, I dunno, delegate redlight to priority medical data. Code Red!

4.2 Airlines

Airline Wi-Fi. Ugh. Nothing says captive audience like havingto pay for the "service" of

dial-up speed Wi-Fi on the plane.And don’t get me started on the pricing. The best I’ve heard

sofar is that passengers will "soon" be offered a "high-speedlike" connection on some airlines.

United is planning onspeeds as high as 9.8 Mbps per plane. Uh, I have twice thatcapacity in my

living room. And at the same price as checkinga bag, I expect it. Li-Fi could easily introduce that

sort ofspeed to each seat's reading light. I’ll be the guy WoWing nextto you. Its better than

listening to you tell me about yourwildly successful son, ma’am.

19

4.3 Smarter Power Plants

Wi-Fi and many other radiation types are bad for sensitiveareas. Like those surrounding

power plants. But power plantsneed fast, inter-connected data systems to monitor things like

demand, grid integrity and (in nuclear plants) coretemperature. The savings from proper

monitoring at a singlepower plant can add up to hundreds of thousands of dollars.Li-Fi could

offer safe, abundant connectivity for all areas ofthese sensitive locations. Not only would this

save moneyrelated to currently implemented solutions, but the draw on apower plant’s own

reserves could be lessened if they haven’tyet converted to LED lighting

4.4 Undersea Awesomeness

Underwater ROVs, those favourite toys of treasure seekersand James Cameron, operate

from large cables that supplytheir power and allow them to receive signals from their

pilotsabove. ROVs work great, except when the tether isn’t longenough to explore an area, or

when it gets stuck on something.If their wires were cut and replaced with light — say from

asubmerged, high-powered lamp — then they would be muchfreer to explore. They could also

use their headlamps tocommunicate with each other, processing data autonomouslyand referring

findings periodically back to the surface, all thewhile obtaining their next batch of orders.

4.5. It Could Keep You Informed and Save Lives

Say there’s an earthquake in New York. Or a hurricane. Takeyour pick — it’s a wacky

city. The average New Yorker maynot know what the protocols are for those kinds of

disasters.Until they pass under a street light, that is. Remember, withLi-Fi, if there’s light, you’re

online. Subway stations andtunnels, common dead zones for most emergencycommunications,

20

pose no obstruction. Plus, in times lessstressing cities could opt to provide cheap high-speed

Webaccess to every street corner.

USES IN VARIOUS AREAS

Can be used in the places where it is difficult to lay the opticalfiber like hospitals. In

operation theatre LiFi can be used formodern medical instruments. In traffic signals LiFi can

beused which will communicate with the LED lights of the carsand accident numbers can be

decreased. Thousand andmillions of street lamps can be transferred to LiFi lamps totransfer data.

In aircraft LiFi can be used for datatransmission.

It can be used in petroleum or chemical plants whereother transmission or frequencies

could be hazardous.

Li-Fi revolution: internet connections using light bulbs are 250 times faster than broadbandLi-Fi,

an alternative to Wi-Fi that transmits data using the spectrum of visible light, has achieved a new

breakthrough, with UK scientists reporting transmission speeds of 10Gbit/s – more than 250

times faster than ‘superfast’ broadband.

The fastest speed previously reported was 3Gbit/s, achieved earlier this year by the Fraunhofer

Heinrich Hertz Institute in Germany. Chinese researchers also claimed this month to have

produced a 150Mbp/s connection, but some experts were doubtful without seeing further proof.

The term Li-Fi was coined by Edinburgh University's Prof Harald Haas during a TED talk in

2011 (see below for video) though the technology is also known as visible light communications

(VLC).

Many experts claim that Li-Fi represents the future of mobile internet thanks to its reduced costs

and greater efficiency compared to traditional Wi-Fi.

Both Wi-Fi and Li-Fi transmit data over the electromagnetic spectrum, but whereas Wi-Fi

utilises radio waves, Li-Fi uses visible light. This is a distinct advantage in that the visible light is

21

far more plentiful than the radio spectrum (10,000 times more in fact) and can achieve far greater

data density.

Li-Fi signals work by switching bulbs on and off incredibly quickly – too quickly to be noticed

by the human eye. This most recent breakthrough builds upon this by using tiny micro-LED

bulbs to stream several lines of data in parallel.

The research was carried out by the Ultra Parallel Visible Light Communications project, a joint

venture between the universities of Oxford, Cambridge, Edinburgh, St Andrews and Strathclyde,

and funded by the Engineering and Physical Sciences Research Council.

Existing LED light bulbs could be converted to transmit Li-Fi signals with a single microchip,

and the technology would also be of use in situations where radio frequencies cannot be used for

fear of interfering with electronic circuitry.

And although Li-Fi bulbs would have to be kept on to transmit data, the bulbs could be dimmed

to the point that they were not visible to humans and yet still functional. One draw-back is that

the data receiver would have to be in sight of the transmitter-bulb as visible light does not

penetrate solid materials.

The makers of Li-Fi note that this quality might actually be an advantage in some scenarios,

making Li-Fi more secure than Wi-Fi with hackers unable to access unsecured internet

connections from out of sight of the transmitter.

Li-Fi, an alternative to Wi-Fi that transmits data using the spectrum of visible light, has achieved

a new breakthrough, with UK scientists reporting transmission speeds of 10Gbit/s – more than

250 times faster than ‘superfast’ broadband.

The fastest speed previously reported was 3Gbit/s, achieved earlier this year by the Fraunhofer

Heinrich Hertz Institute in Germany. Chinese researchers also claimed this month to have

produced a 150Mbp/s connection, but some experts were doubtful without seeing further proof.

22

The term Li-Fi was coined by Edinburgh University's Prof Harald Haas during a TED talk in

2011 (see below for video) though the technology is also known as visible light communications

(VLC).

Many experts claim that Li-Fi represents the future of mobile internet thanks to its reduced costs

and greater efficiency compared to traditional Wi-Fi.

Both Wi-Fi and Li-Fi transmit data over the electromagnetic spectrum, but whereas Wi-Fi

utilises radio waves, Li-Fi uses visible light. This is a distinct advantage in that the visible light is

far more plentiful than the radio spectrum (10,000 times more in fact) and can achieve far greater

data density.

Li-Fi signals work by switching bulbs on and off incredibly quickly – too quickly to be noticed

by the human eye. This most recent breakthrough builds upon this by using tiny micro-LED

bulbs to stream several lines of data in parallel.

The research was carried out by the Ultra Parallel Visible Light Communications project, a joint

venture between the universities of Oxford, Cambridge, Edinburgh, St Andrews and Strathclyde,

and funded by the Engineering and Physical Sciences Research Council.

Existing LED light bulbs could be converted to transmit Li-Fi signals with a single microchip,

and the technology would also be of use in situations where radio frequencies cannot be used for

fear of interfering with electronic circuitry.

And although Li-Fi bulbs would have to be kept on to transmit data, the bulbs could be dimmed

to the point that they were not visible to humans and yet still functional. One draw-back is that

the data receiver would have to be in sight of the transmitter-bulb as visible light does not

penetrate solid materials.

The makers of Li-Fi note that this quality might actually be an advantage in some scenarios,

making Li-Fi more secure than Wi-Fi with hackers unable to access unsecured internet

connections from out of sight of the transmitter.

23

Visible light communications

Many people’s first exposure to optical wireless technology was VLC. This emerging technology

offers optical wireless communications by using visible light. Today, it is seen as an alternative

to different RF-based communication services in wireless personal-area networks. An additional

opportunity is arising by using current state-of-the-art LED lighting solutions for illumination

and communication at the same time and with the same module. This can be done due to the

ability to modulate LEDs at speeds far faster than the human eye can detect while still providing

artificial lighting.Thus while LEDs will be used for illumination, their secondary duty could be

to ‘piggyback’ data communication onto lighting systems. This will be particularly relevant in

indoor ‘smart’ lighting systems, where the light is always ‘on.’Other examples for outdoor use

include intelligent traffic systems to exchange data between vehicles, and between vehicles and

road infrastructure like traffic lights and control units. Alternatively, the LEDs’ primary purpose

could be to transmit information while the secondary purpose of illumination would be to alert

the user to where the data is being transmitted from.In contrast to infrared, the so-called “what

you see is what you send” feature can be used to improve the usability of transmitting data at

shorter point-to-point distances between different portable or fixed devices. There, illumination

can be used for beam guiding, discovery or generating an alarm for misalignment.The premise

behind VLC is that because lighting is nearly everywhere, communications can ride along for

nearly free. Think of a TV remote in every LED light bulb and you’ll soon realise the

possibilities of this technology.

(A) GigaDock (B) GigaBeam

24

(c) GigaShower (D) GigaMIMO

Fig. 2: GigaSpeed usage models (Images courtesy: TriLumina Corp.)

One of the biggest attractions of VLC is the energy saving of LED technology. Nineteen per cent

of the worldwide electricity is used for lighting. Thirty billion light bulbs are in use worldwide.

Assuming that all the light bulbs are exchanged with LEDs, one billion barrels of oil could be

saved every year, which again translates into energy production of 250 nuclear power

plants.Driven by the progress of LED technology, visible light communication is gaining

attention in research and development. The VLC Consortium (VLCC) in Japan was one of the

first to introduce this technology.After establishing a VLC interest group within the IEEE 802.15

wireless personal-area networks working group, the IEEE 802.15.7 task group was established

by the industry, research institutes and universities in 2008. The final standard was approved in

2011. It specifies VLC comprising mobile-to-mobile (M2M), fixed-to-mobile (F2M) and

infrastructure-to-mobile (I2M) communications. There, the focus is on low-speed, medium-range

communications for intelligent traffic systems and on high-speed, short-range M2M and F2M

communications to exchange, for example, multimedia data. Data rates are supported from some

100 kbps up to 100 Mbps using different modulation schemes.Other standardisation groups are

working on standardised optical wireless communication (OWC) solutions using visible and

infrared light. The most important groups are IrDA with its new 10 Giga-IR working group, ISO

and ICSA.Li-Fi—the superset of  VLC & Co.VLC represents only a fraction of what appears

to be a much larger movement towards optical wireless technologies in general. This larger

world has been dubbed ‘Li-Fi’ (Light Fidelity) by people such as Dr Harald Haas of Edinburgh

University and organisations such as the Li-Fi Consortium.In that connection, Li-Fi comprises

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several optical wireless technologies such as optical wireless communication, navigation and

gesture recognition applied for natural user interfaces (Fig. 1). Thus it provides a completely new

set of optical technologies and techniques to offer users add-on as well as complementary

functionalities compared to well-known and established RF services. This could reach from a

new user experience regarding communication speeds in the gigabit-class to bridge the well-

known spec-trum crunch, over to precise indoor positioning or controlling video games,

machines or robots with entirely new natural user interfaces. Finally, these and many more could

be merged to a full-featured Li-Fi cloud providing wireless services for other future applications

as well.What Li-Fi stands forLi-Fi comprises a wide range of frequencies and wavelengths,

from the infrared through visible and down to the ultraviolet spectrum. It includes sub-gigabit

and gigabit-class com-munication speeds for short, medium and long ranges, and unidirectional

and bidirectional data transfer using line-of-sight or diffuse links, reflec-tions and much more. It

is not limited to LED or laser technologies or to a particular receiving technique. Li-Fi is a

framework for all of these providing new capabilities to current and future services, applications

and end users.Usage modelsWithin a local Li-Fi cloud several databased services are supported

through a heterogeneous communication sys-tem. In an initial approach, the Li-Fi Consortium

defined different types of technologies to provide secure, reliable and ultra-high-speed wireless

communication interfaces. These technologies included giga-speed technologies, optical mobility

technologies, and navigation, precision location and gesture recognition technologies.For giga-

speed technologies, the Li-Fi Consortium defined GigaDock, GigaBeam, GigaShower, GigaSpot

and GigaMIMO models (Fig. 2) to address different user scenarios for wireless indoor and

indoor-like data transfers. While GigaDock is a wireless docking solution including wireless

charging for smartphones tablets or notebooks, with speeds up to 10 Gbps, the GigaBeam model

is a point-to-point data link for kiosk applications or portable-to-portable data exchanges. Thus a

two-hour full HDTV movie (5 GB) can be transferred from one device to another within four

seconds.GigaShower, GigaSpot and Giga-MIMO are the other models for in-house

communication. There a transmitter or receiver is mounted into the ceiling connected to, for

example, a media server. On the other side are portable or fixed devices on a desk in an office, in

an operating room, in a production hall or at an airport. GigaShower provides unidirectional data

services via several channels to multiple users with gigabit-class com-munication speed over

several metres. This is like watching TV channels or listening to different radio stations where no

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uplink channel is needed. In case GigaShower is used to sell books, music or movies, the

connected media server can be accessed via Wi-Fi to process payment via a mobile device.

GigaSpot and GigaMIMO are optical wireless single- and multi-channel HotSpot solutions

offering bidirectional gigabit-class communication in a room, hall or shopping mall for

example.How Li-Fi worksImagine yourself walking into a mall where GPS signals are

unavailable but the mall is equipped with ceiling bulbs that create their own ‘constellation’ of

navigation beacons. As the camera of your cellphone automatically receives these signals, it

switches your navigation software to use this information to guide you to the ATM machine

you’re looking for.You conclude your ATM transaction and notice the GigaSpot sign for instant

digital movie downloads. You pick out that new Tom Cruise movie using your phone’s payment

facility, and then download within a few seconds the high-definition movie into the GigaLink

flash drive plugged into the USB port of your smartphone.As you walk away, your phone

notifies you that the leather jacket Tom featured in the movie is on sale nearby. You walk over

towards the show window and your image comes up on the screen, wearing that coveted jacket.

You turn and pose while the image matches your orientation and body gestures for a ‘digital

fitting.’ When you walk into the store, the clerk hands you the actual jacket in exactly your

size.On the verge of a breakthroughFirst applications of Li-Fi have been put to use already, for

example, in hospitals where RF signals are a threat due to interference problems with medical

equipment such as blood pumps and other life supporting instruments. Axiomtek Europe

presented such a product at the Embedded World exhibition in Nürn-berg, Germany. The

prototype of a mobile phone with an incorporated VLC system was presented by Casio at the

Consumer Electronics Show in Las Vegas in January this year. In the coming years, we will see

more Li-Fi products entering the market, both in the industrial as well as consumer markets.

Imagine only needing to hover under a street lamp to get public internet access, or downloading

a movie from the lamp on your desk. There's a new technology on the block which could, quite

literally as well as metaphorically, 'throw light on' how to meet the ever-increasing demand for

high-speed wireless connectivity. Radio waves are replaced by light waves in a new method of

data transmission which is being called Li-Fi.

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light-emitting diodes can be switched on and off faster than the human eye can detect, causing

the light source to appear to be on continuously

A flickering light can be incredibly annoying, but has turned out to have its upside, being

precisely what makes it possible to use light for wireless data transmission. Light-emitting diodes

(commonly referred to as LEDs and found in traffic and street lights, car brake lights, remote

control units and countless other applications) can be switched on and off faster than the human

eye can detect, causing the light source to appear to be on continuously, even though it is in fact

'flickering'. This invisible on-off activity enables a kind of data transmission using binary codes:

switching on an LED is a logical '1', switching it off is a logical '0'. Information can therefore be

encoded in the light by varying the rate at which the LEDs flicker on and off to give different

strings of 1s and 0s. This method of using rapid pulses of light to transmit information wirelessly

is technically referred to as Visible Light Communication (VLC), though its potential to compete

with conventional WiFi has inspired the popular characterisation Li-Fi.

The concept of Li-Fi is currently attracting a great deal of interest, not least because it may offer

a genuine and very efficient alternative to radio-based wireless. As a growing number of people

and their many devices access wireless internet, the airwaves are becoming increasingly clogged,

making it more and more difficult to get a reliable, high-speed signal. The opportunity to exploit

a completely different part of the electromagnetic spectrum is therefore very appealing. As well

as being a potential solution to our ever-increasing hunger for bandwidth, Li-Fi has other

advantages over WiFi, such as being safe to use on an aircraft, in hospitals and medical devices,

and even underwater, where WiFi doesn't work at all.

Research suggests that Li-Fi has the potential to be faster, safer and cheaper than

conventional WiFi technology. In more ways than one, it looks like the future of wireless

communication definitely has a 'bright side'.

Background – Li-Fi

The technology underpinning Li-Fi was pioneered by German physicist Harald Haas, currently

based at the University of Edinburgh in the UK. Haas coined the term Li-Fi in 2011 in the

context of a talk presenting the new technology at the TED (Technology Entertainment and

Design) Global conference. The word quickly entered common parlance as an instantly

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recognisable alternative to WiFi. Both terms are examples of abbreviations linguists sometimes

describe as clipped forms, i.e. WiFi = wireless fidelity, Li-Fi = light fidelity.

Haas's research project, originally known as D-Light (short for Data Light), is now set to launch

a prototype Li-Fi application under the name of newly-formed company VLC (Visible Light

Communication) Ltd, which was set up to commercialize the technology.

Would you like to use this BuzzWord article in class? Visit onestopenglish.com for tips and

suggestions on how to do just that! This downloadable pdf contains a student worksheet which

includes reading activities, vocabulary-building exercises and a focus on expressions

with light and abbreviations.

We use it in our everyday life, private life, business life as currently 2G, 3G, 4G uses radio

waves. Wireless communication has become an utility like also have 5 billion of mobile phones

electricity and water .Mobile phones transmit 600TB of data every month.We have 1.4 million

cellular base stations deployed .

The LiFi product consists of 4 primary sub-assemblies: 1.Bulb 2.RF Power Amplifier Circuit

(PA) 3.Printed Circuit Board (PCB) 4.Enclosure 1. The high concentration of energy in the

electric field vaporizes the contents of the bulb to a plasma state at the bulb’s center; this

controlled plasma generates an intense source of light. 2. The PCB controls the electrical inputs

and outputs of the lamp and houses the microcontroller used to manage different lamp functions.

3.An RF (radio-frequency) signal is generated by the solid-state PA and is guided into an electric

field about the bulb. 4. All of these subassemblies are contained in an aluminum enclosure.

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.

You Can Use Li-Fi In Hospitals And Aircrafts Also. Cheaper Then WiFi , Since Visible Light

Spectrum Is A Free Spectrum Band. No License Needed. Thousands And Millions Of Street

Lamps Can Be Converted To Li-fi Spots. Light Is Readily Available In Every Part Of The

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World. This Makes It Easy For People In Airplanes To Work On The Internet. There Are An

Estimated 14 Billion Light Sources On Earth And Each Can Be Easily Converted Into A Li-Fi

Hotspot.

Advantages of LiFi

High efficient.Led light consumes less energy. Data through illumination and thus data

transmission comes for free. We have the infrastructure available and already installed.

Efficiency Light box are already present. 10000times more spectrum than Radio waves.

Advantages of Li-Fi Other Advantages of Li-Fi Technology Capacity

Interference with other electromagnetic waves makes the transmitting data to distort Light

cannot approach the range and penetration of radio waves High installation cost of the VLC

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

transmitter. Interferences from external light sources like sun light, normal bulbs, and opaque

materials in the path of transmission will cause interruption in the communication. Visible light

cannot penetrate through solid objects There should be line of sight between sender and

receiver

Limitations of LiFi

To prove that the light bulb was the source of data stream, he periodically blocked the beam of

light, causing the connection to drop. Dr. Harald Hass demonstrated his invention using an

ordinary table lamp that successfully transmitted data at speeds exceeding 10Mbps . Yes, this is

already proven.

LiFi is Proven or Not ? Is it a proven technology? Video Demonstration of LiFi Li-Fi

Demonstration by Harald Hass at TED talk, 2013 It can used in petroleum or chemical plants

where other transmission or frequencies could be hazardous. In aircraft Li-Fi can be used to

transmit data.

Thousands and millions of street lamps can be transferred to Li-Fi lamps to transfer data.

In traffic signals Li-Fi can be used which will communicate with the LED lights of the cars and

accident numbers can be decreased. Can be used in the places where it is difficult to lay the

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optical fiber like hospitals. In operation theatre Li-Fi can be used for modern medical

instruments.

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 Wi-Fi hotspot to transmit wireless

data and we will proceed onwards the Cleaner, Greener, Safer and Brighter future.

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CONCLUSION

The possibilities are numerous and can be explored further. If his 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. The concept of

Li-Fi is currently attracting a great deal of interest, not least because it may offer a genuine and

very efficient alternative to radio-based wireless. As a growing number of people and their many

devices access wireless internet, the airwaves are becoming increasingly clogged, making it more

and more difficult to get a reliable, high-speed signal. This may solve issues such as the shortage

of radio-frequency bandwidth and also allow internet where traditional radio based wireless isn’t

allowed such as aircraft or hospitals. One of the shortcomings however is that it only work in

direct line of sight.

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Refferences:-

1:- http://timesofindia.indiatimes.com/home/science/Now-just-light-a-bulb-to-switch-on-your-

broadband/articleshow/9713554.cms

2: - http://oledcomm.com/lifi.html

3:- http://en.wikipedia.org/wiki/Li-Fi

4:- http://slideshare.com/li-fitech.html

[1] seminarprojects.com/s/seminar-report-on-lifi

[2] http://en.wikipedia.org/wiki/Li-Fi

[3] http://teleinfobd.blogspot.in/2012/01/what-is-lifi.html

[4] technopits.blogspot.comtechnology.cgap.org/2012/01/11/a-lifi-world/

[5] www.lificonsortium.org/

[6] the-gadgeteer.com/2011/08/29/li-fi-internet-at-thespeed-of-light/

[7] en.wikipedia.org/wiki/Li-Fi

[8] www.macmillandictionary.com/buzzword/entries/Li-Fi.html

[9] dvice.com/archives/2012/08/lifi-ten-ways-i.php

[10] 8. Will Li-Fi be the new Wi-Fi?, New Scientist, byJamie Condliffe, dated 28 July 2011

[11] http://www.digplanet.com/wiki/Li-Fi

[12] 10.”Visible-light communication: Tripping the lightfantastic: A fast and cheap optical

version of Wi-Fi iscoming”, Economist, dated 28Jan 2012

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