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UNIVERSITY OF INFORMATION TECHNOLOGY &SCIENCES

Submitted By :

Showrav Mazumder

ID : 10530053

Md.Mozahid Hossain

ID : 11330336 CSE

Study Paper on

. Li-Fi Technology [The latest technology in wireless]

Submitted To: Joya Das (Lecturer of UITS)

Date of Submission : 08-03-2014

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Abstract

For the vast increasing gadgets, their usage and developments led to the progression of

Wi-Fi which provides a latest technology, it’s called Li-Fi. Li-Fi is a latest technology

that makes use of LED light which helps in the transmission of data much more faster

and flexible than data that can be transmitted through Wi-Fi. Light reaches nearly

everywhere so communication can also go along with light easily. Light Fidelity is a

branch of optical wireless communication which is an emerging technology. By using

visible light as transmission medium, Li-Fi provides wireless indoor communication. The

bit rate achieved by Li-Fi cannot be achieved by Wi-Fi. Prof. Dr. herald Haas, the

professor of mobile communications at the University of Edinburgh, UK, first time

publically displayed the proof of Light Fidelity(Li-Fi), a method of Visible Light

communication(VLC). Li-Fi is the transfer of data through light by taking fiber out of

fiber optics and sending data through LED light.

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Contents

Page

1. Introduction……………………………………………………………... 3

2. History…………………………………………………………………... 4

2.1. Present scenario …………………………………………………………… 5

3. Working Technology …………………………………………………... 6

3.1. Basic Concept ..………………………………………………………...... 6

3.2. How it’s works …………………………………………………………..... 6

3.3. Data Transmission ………………………………………………………… 7

3.4. Why Visible Light Communication ………………………………............. 7

3.5. Design of Li-Fi ………………………………………………………….. 8

3.6. What Makes A Fiber Optics Cable……………………………………..... 8

3.7. Implementation ………………………………………………………….. 9

4. Applications …………………………………………………………... 11

5. Features ..…………………………………………………………….... 15

6. Limitations….………………………………………………………..... 16

6.1. Comparisons ………………………………………………................ 16

7. Conclusion…………………………………………………………….. 18

8. References………………………………………………………….…. 19

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Introduction

Li-fi basically known as ―light fidelity‖ is an outcome of twenty first century. The basic

ideology behind this technology is that the data century. 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. As the transmission of the data takes place through the

light emitting diodes (LED’s) the amount is comparatively small .In modern times, it is

called as the optimized version of WI-FI . 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 much

more. The technology truly began during the 1990's in countries like in this spectrum and

just counting on the bulbs in use, it also multiplies to 10,000 times more availability as an

infrastructure, globally. The advantageous thing is the wireless communication which

decreases the cost enormously. HARALD HASS, who is considered to be the father of

Li-fi from university of Edinburgh, UK says that the heart of this technology lies in the

intensity and the potential of the light emitting diodes. The major reason which lead the

modern man through this invention is that the confinement of Wi-Fi to comparatively

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

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

technology. And the solution to this problem was the Li-fi technology. It has been

designed in such a way that it overcomes the disadvantages that occurs during the usage

of Wi-Fi. In general terms, Li-fi works even under water thereby causing a great benefit

to the military operations. The physicists envisions that this technology would make a

great difference between the assumption and the proof in this case. The demonstration

took place using two Casio smart phones. The data was made to exchange between the

phones using light. Even though the distance was nominal, it is sure that there would be a

rapid increase in the distance of transmission. As there is a limited amount of Radio

based wireless spectrum available a number of companies formed a consortium called

Li-fi consortium in order to promote high speed optical wireless systems. The members

of this consortium believes that a speed of 10Gbps can be achieved in no time. If this

would be possible then a high clarity image would take about 30 seconds to download!!

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History

Professor Harald Haas, from the University of Edinburgh in the UK, is widely

recognized as the original founder

of Li-Fi. Harald haas continues to

hit the world that there is a

possibility for communication

through light.LI-FI technology has

the possibility to change how we

access the internet, stream videos,

receive emails and much more.

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.

This type of light would come in

familiar forms such as infrared,

ultraviolet and visible light. Research

into VLC has been conducted in earnest since 2003, mainly in the UK, US, Germany,

Korea and Japan. Experiments have shown that LEDs can be electronically adapted to

transmit data wirelessly as well as to provide light. VLC is faster, safer and cheaper than

other forms of wireless internet, advocates say -- and so could eliminate the need for

costly mobile-phone radio masts Haas has a small lab stuffed with equipment, including

the now-famous table lamp and its box of electronics. It was here in 2007 that his

research assistant, Mostafa Afgani, first sent data using light signals. Haas's invention

centuries on how these signals are modulated: the information, embedded within visible

light emitted from the LEDs, is transmitted by means of many subtle changes made to the

intensity of the light at the ultra-high rate of 100 million cycles per second (100MHz).

The photo-detector in Haas's box monitors these tiny variations and converts them back

into a digital signal, from which the transmitted information is extracted. In October 2011

a number of companies and industries formed the Li-Fi Consortium, to promote high-

speed optical wireless system sand to enhance the limited bandwidth provided by radio-

based light communication is this method of using rapid pulses of light to transmit

information wirelessly.

Fig : Prof. Harald Hass

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2.1. Present scenario

At present we have as many as 1.5 million radio wave base stations across the

globe.

We also have close to 5 billion mobile connections which transmit a data over

600TB.

1.5 million 5 billion

Figure-1: The present scenario.

This penetration of mobile devices into our lives has led to a wide recognition of

WI-FI technology.

Radio Spectrum is congested but the demand for wireless data double each year

.Everything, it seems want to use wireless data but the capacity is drying up.

So what can carry this excess demand in the future.

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3. Working Technology

Basic Concept: Li-Fi technology is a wireless communication system based on the use of visible light between the blue (670 THz) and red (480 THz). Unlike Wi-Fi which uses the radio part of the electromagnetic spectrum, Li-Fi uses the optical spectrum. The principle of Li-Fi is based on sending data by amplitude modulation of the light sources in a well-defined and standardized way. The principle is simple: the LED turns on and off at high speed and is not visible to humans. This ribbon of on and off signals is interpreted to create binary streams of 0 and 1. Because there are no battling light frequencies like that of the radio frequencies in Wi-Fi, Li-Fi is thought to be 80% more efficient. Which means it can reach speeds of up to 1Gbps. Is this the future? Li-Fi differs from fiber optic because the Li-Fi protocol layers are suitable for wireless communication over short distances (up to ten meters). This puts Li-Fi in a unique position of extremely fast wireless communication over short distances. The technology has already attained IEEE standard certification and is currently being tested at the  Oledcomm head quarters  in France. It is expected that Li-Fi could be ready for use as soon as 2014.

3.1. How it’s Works

The working procedure is very simple, if the light is on then transmit a digital 1, if it’s off

transmit a 0. The LEDs can be switched on and off very quickly which gives nice

opportunities for transmitting data.

Fig-2: Li-Fi works

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`

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

All one has to do is to vary the rate at which the LEDs flicker depending upon the data

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

the 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.

3.2. Data Transmission

As WI-FI hotspot and cloud computing are rapidly increasing reliable signal is bound to

suffer. Speed and security are also major concerns. They are vulnerable to hackers as it

penetrates through walls easily. LI-FI is said to overcome this. This new technology is

comparable to infrared remote controls which send data through an LED light bulb that

varies in intensity faster than the human eye can see. In near future we can see data for

laptops, smart phones and tablets transmitted through the light in a room. Li-Fi(Light

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

on Visible Light Communication(VLC).

3.3. Why Visible Light Communication

At first Radio waves, its expensive and less secure. Infrared, due to eye safety regulation

can only base with low power. Gama rays can not be used as they could be dangerous.

Ultraviolet light is good for place without people, but otherwise dangerous for the human

body.

Fig-3: Why only VLC [ Visible light Communication].

But, Visible rays is safe to use larger bandwidth.

VLC is a data communication medium, which uses visible light between 400 THz (780

nm) and800 THz (375 nm) as optical carrier for data transmission and illumination. Fast

pulses are used for wireless transmission. Communication system components are:

Radio Waves

Infrared Rays

Gama

Rays Ultraviolet

Rays X- Rays

Visible Rays

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1. A high brightness white LED which acts as a communication source.

2. Silicon photo diode which shows good response to visible wavelength region.

LED illumination can be used as a communication source by modulating the LED light

with the data signal. The LED light appears constant to the human eye due to the fast

flickering rate. The high data rate can be achieved by using high speed LED’s and

appropriate multiplexing techniques. Each LED transmits at a different data rate which

can be increased by parallel data transmission using LED arrays. Many different reasons

exist for the usage of LED light in spite of fluorescent lamp, incandescent bulb etc which

are available.

3.4. Design of Li-Fi

Li-Fi architecture consists numbers of Led bulbs or lamps, many wireless devices

such as PDA, Mobile Phones, and laptops. Important factors we should consider while

designing Li –Fi as following:

1. Presence of Light must be line-of-sight.

2. Lamp driver where internet connection, switch and LED lamp connected.

3. For better performance use LED bulbs.

4. A photo detector received data.

3.5. What Makes A Fiber Optics Cable

Typically, fiber optic cables are made up of various parts depending on what cable I

want. To better understand, imagine looking at a bulls-eye, the outer most circle would

be the cable jacket or what you see on the outside of a fiber optic cable. The core is where

the data is sent as light from one end of the cable to another. One key important fact is

that the light is reflected off of mirrors inside the cable which helps get the light waves to

its destination.

.

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Fig -4: Using Fiber Optics Cable.

Generally, fiber optic cables are wires that transmit data. through an extremely thin layer

layers of glass or plastic threads. These threads are the actual fibers in a fiber optic

cable. The relationship to LI-FI technology is in the regard that data travels through

the fiber in the form of light which is then translated into 1's and 0's, the data part. One

of the key advantages to using light as a data transmitter is its massive bandwidth

which is what makes fiber optics popular today. However, fiber optics are notoriously

expensive but may soon replace most existing traditional metal cables.

3.6. Implementation

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

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Fig-5: Implementation of Li-Fi.

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.

Fig -6: Architecture of Li-Fi

Implementation of Li-Fi given in the figure. In figure a internet connection is connected

to the lamp driver . A switch connected with lamp driver and LED lamp also connected

this lamp driver through fiber optics cable. Now a receiving device named photo detector

is using for receive signal and processing , this device is connected with PC or Laptop’s

LAN port. On one end all the data on the internet will be streamed to a lamp driver when

the LED is switched on the microchip converts the digital data in form of light. The light

sensitive device photo detector receives the signal and converts it back into original data.

This method of using rapid pulses of light to transmit information wirelessly is

technically referred as Visible Light Communication.

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4. APPLICATIONS

There is a wide necessity for data transfer and by the end of the day every field involves

the use of technologies.one such technology is Li-Fi which can have its applications

extended in areas where the Wi-Fi technology lack its presence like medical technology,

power plants and various other areas where Li-Fi proved it excellence of the undersea

awesomeness.

Spectrum Relief:

Excess capacity demands of cellular networks can be off-loaded to Li-Fi networks where

available. This is especially effective on the downlink where bottlenecks tend to occur.

Mobile Connectivity: Laptops, smart phones, tablets and other mobile devices can interconnect directly using

Li-Fi. Short range links give very high data rates and also provides security.

Hazardous Environments: Li-Fi provides a safe alternative to electromagnetic

interference from radio frequency communications in environments such as mines and

petrochemical plants.

Aviation: Li-Fi can be used to reduce weight and cabling and add flexibility to seating layouts in

aircraft passenger cabins where LED lights are already deployed. In-flight entertainment

(IFE) systems can also be supported and integrated with passengers’ own mobile devices.

Underwater Communications: Due to strong signal absorption in water, RF use is impractical. Acoustic waves have

extremely low bandwidth and disturb marine life. Li-Fi provides a solution for short-

range communications.

Reduction in accident numbers: LED headlights and tail-lights are being

introduced. At traffic signals, we can use LIFI in

order to communicate with LED lights of the cars by the number of accidents can be

reduced. Data can be easily transferred by making use of LIFI lamps with the street

lamps. This can be used for vehicle-to-vehicle and vehicle-to-roadside communications.

This can be applied for road safety and traffic management.

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RF Avoidance: Some people claim they are hypersensitive to radio frequencies and are looking for an

alternative. Li-Fi is a good solution to this problem.

Location Based Services (LBS): Highly accurate location-specific information services such as advertising and navigation

that enables the recipient to receive appropriate, pertinent information in a timely manner

and location.

Airlines:

Airline Wi-Fi, nothing says captive audience like having to pay for the "service" of dial-

up speed Wi-Fi on the plane. And don’t get me started on the pricing. The best so far is

that passengers will "soon" be offered a "high-speed like" connection on some

airlines. United is planning on speeds as high as 9.8 Mbps per plane. Twice that

capacity in my living room. And at the same price as checking a bag, Li-Fi could easily

introduce that sort of speed to each seat's reading light.

Smarter Power Plants: Wi-Fi

and many other radiation types are bad for sensitive areas. Like those surrounding power

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

demand, grid integrity and (in nuclear plants) core temperature. The savings from

proper monitoring at a single power plant can add up to hundreds of thousands of

dollars. Li-Fi could offer safe, abundant connectivity for all areas of these sensitive

locations. Not only would this save money related to currently implemented solutions,

but the draw on a power plant’s own reserves could be lessened if they haven’t yet

converted to LED lighting.

Education systems:

As with the advancement of science the latest technology is the LIFI which is the fastest

speed internet access service.so this will leads to the replacement of WIFI at institutions

and at companies so that all the people can make use of LIFI with same speed intended in

a particular area.

Usage-Models:

Within a local Li-Fi cloud several database services are supported through a

heterogeneous communication system. 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

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technologies, optical mobility technologies, and navigation, precision location and

gesture recognition technologies. For Giga-speed technologies, the Li-Fi Consortium

defined Giga Dock, Giga-Beam, Giga-Shower, Giga-Spot and Giga-MIMO models to

address different user scenarios for wireless indoor and indoor-like data transfers. While

Giga Dock is a wireless docking solution including wireless charging for smartphones,

tablets or notebooks, with speeds up to 10Gbps, the Giga Beam 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. Giga shower, Giga Spot 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. Giga Shower

provides unidirectional data services via several channels to multiple users with gigabit-

class communication speed over several maters. This is like watching TV channels or

listening to different radio stations where no uplink channel is needed. In case Giga

Shower 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. Giga-Spot and Giga-MIMO

are optical wireless single- and multi-channel Hot-Spot solutions offering bidirectional

gigabit-class communication in a room, hall or shopping mall for example.

Extends our life span:

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

Operating rooms do not allow Wi-Fi over radiation concerns, and there is also that

whole lack of room. dedicated spectrum. While Wi-Fi is in place in many hospitals,

interference from cell phones and computers can block signals from monitoring

equipment. Li-Fi solves both problems: lights are not only allowed in operating

rooms, but tend to be the most glaring (pun intended) fixtures in the room. And, as

Haas mentions in his TED Talk, Li-Fi has 10,000 times the spectrum of Wi-Fi, so

maybe we can, I delegate red light to priority medical data. Code Red!

Replacement for others technologies:

This technology doesn’t deal with radio waves, so it can easily be used in the places

where Bluetooth, infrared, WIFI and Internet are banned. In this way, it will be most

helpful transferring medium for us. It includes other benefits like:

*A very wide spectrum over visible wave length range.

* Extremely high colour fidelity.

*Instant start time.

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*Easy terminal Management.

*Dynamic dark i.e. brightness Modulation of lamp output to enhance video contrast.

*Trouble-free integration into existing light engine platform.

Li-Fi is the upcoming and on growing technology acting as competent

for various other developing and already invented technologies. Since

light is d major source for transmission in this technology it is very advantageous and

implementable in various fields that can’t be done with

the Wi-Fi and other technologies. Hence the future applications of the

Li-Fi can be predicted and extended to different platforms like education

fields, medical field, industrial areas and many other fields.

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5. Features

Li-Fi offers a number of key benefits over Wi-Fi but is inherently a complementary

technology.

5.1. Capacity

Bandwidth:

The visible light spectrum is plentiful (10,000 more than RF spectrum), unlicensed and

free to use.

Data density: Li-Fi can achieve about 1000 times the data density of Wi-Fi because

visible light can be well contained in a tight illumination area whereas RF tends to spread

out and cause interference.

High speed: Very high data rates can be achieved due to low interference, high device

bandwidths and high intensity optical output.

Planning: Capacity planning is simple since there tends to be illumination infrastructure

where people wish to communicate, and good signal strength can literally be seen.

5.2. Efficiency

Low cost: Requires fewer components than radio technology.

Energy: LED illumination is already efficient and the data transmission requires

negligible additional power.

Environment: RF transmission and propagation in water is extremely difficult but Li-Fi

works well in this environment.

Safety: Life on earth has evolved through exposure to visible light. There are no known

safety or health concerns for this technology.

Non-hazardous: The transmission of light avoids the use of radio frequencies which can

dangerously interfere with electronic circuitry in certain environments.

Security.

Containment: It is difficult to eavesdrop on Li-Fi signals since the signal is confined to a

closely defined illumination area and will not travel through walls.

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Control: Data may be directed from one device to another and the user can see where the

data is going; there is no need for additional security such as pairing for RF

interconnections such as Bluetooth.

6. Limitations of Li-Fi

The main problem is that light can’t pass through objects, so if the receiver is

inadvertently blocked in any way, then the signal will immediately cut out. ―If the light

signal is blocked, or when you need to use your device to send information — you can

seamlessly switch back over to radio waves‖, Harald says.

Reliability and network coverage are the major issues to be considered by the

companies while providing VLC services. Interference from external light sources like

sun light, normal bulbs; and opaque materials in the path of transmission will cause

interruption in the communication.

High installation cost of the VLC systems can be complemented by large-scale

implementation of VLC though Adopting VLC technology will reduce further operating

costs like electricity charges, maintenance charges etc.

This research report categorizes the global VLC technology market; based on

component, applications, and geography. Li-Fi uses light-emitting diodes (LEDs) which

are rapidly gaining in popularity for standard light bulbs and other domestic and

commercial purposes. They are expected to be ubiquitous in 20 years. VLC is not in

competition with Wi-Fi, Prof. Haas says, it is a complimentary technology that should

eventually help free up much needed space within the radio wave spectrum.

We still need Wi-Fi we still need radio frequency cellular systems. You can’t have a

light bulb that provides data to a high-speed moving object or to provide data in a

remote area where there are trees and walls and obstacles behind,‖ he says.

6.1. Comparison between Li-Fi / Wi-Fi

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. Both Wi-Fi and Li-Fi transmit

data over the electromagnetic spectrum, but whereas Wi-Fi utilizes 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. It

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acquired this name due to the similarity to WI-FI, only using light instead of radio. WI-FI

is great for general wireless coverage within buildings, and li-fi is ideal for high density

wireless data coverage in confined area and for relieving radio interference issues, so the

two technologies can be considered complimentary.

Below given a comparison table of Li-Fi and Wi-Fi

Fig- Table of Comparison between Li-Fi / Wi-Fi

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Conclusion

The Idea of Li-Fi technology currently attracting us a great deal of interest because it’s

latest and very efficient alternative to radio-based wireless technology. 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 hotspot to transmit wireless data and

we can proceed toward the cleaner, greener, safer and brighter future. 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 short age of radio frequency bandwidth

and also allow internet where traditional radio based wireless is not 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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References

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

2.http://www.digplanet.com/wiki/Li-Fi.

3. the-gadgeteer.com/2011/08/29/Li-Fi-internet-at-the speed-of-light.

4. Wireless data from every light bulb Harald Haas, TED Global, Edinburgh, July 2011.

5. www.lificonsortium.org

6. www.macmillandictionary.com/buzzword/entries/Li- Fi.html

7. technopits.blogspot.comtechnology.cgap.org/2012/01/11/a-lifi-world/

8. ―Visible-light communication: Tripping the light fantastic: A fast and cheap optical version of Wi-Fi

iscoming‖,Economist, dated 28 Jan 2012

9.www.lificonsortium.org

10. seminarprojects.com/s/seminar-report-on-lifihttp://teleinfobd.blogspot.in/2012/01/what-is-lifi.html

11. advice.com/archives/2012/08/lifi-ten-ways-i.php

15. Will Li-Fi be the new Wi-Fi?, New Scientist, byJamieCondliffe, dated 28 July 2011

16. http://www.digplanet.com/wiki/Li-Fi.