4th [2015] college of computing sciences and information...

4th International Conference on System Modeling & Advancement in Research Trends (SMART) College of Computing Sciences and Information Technology (CCSIT) ,Teerthanker Mahaveer University , Moradabad [2015]

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Li-Fi(Light Fidelity) Technology Sonali Bhattacharya1, Manish Joshi2,

1MCA Lateral, 1College of Computing Sciences and Information Technology, Teerthanker Mahaveer University

Moradabad [email protected]

[email protected] Abstract— whether we are 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. One German physicist ,DR. Harald Haas, has come up with a solution he calls ―Data Through Illuminationǁ—taking the fibre out of fibre 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, Smartphone’s, and tablets is transmitted through the light in a room Keywords— LED (light emitting diode), VLC (visible light communication)

I. INTRODUCTION 1) Li-Fi Is A Technology That Uses The Light

Emitting Diodes To Transmit The Data Wirelessly.

2) HARALD HAAS, who is considered to be the father of Li-Fi from University of Edinburgh.

3) Li-Fi Is Fast And Cheap Optical Version Of Wi-Fi , Based On Visible Light Communication(VLC);

4) 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.

5) 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.

II. WORKING TECHNOLOGY

How It Works: This brilliant idea was first showcased by Harald Haas from University of Edinburgh, UK, in his TED Global talk on VLC. He explained,” 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. So what you require at all are some LEDs and a controller that code data into those LEDs. We have to just 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 you can download a full high-definition film in just 30


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seconds. Simply awesome! But blazingly fast data rates and depleting bandwidths worldwide are not the only reasons that give this technology an upper hand. Since Li-Fi uses just the light, it can be used safely in aircrafts and hospitals that are prone to interference from radio waves. This can even work underwater where Wi-Fi fails completely, thereby throwing open endless opportunities for military operations. 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. 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 it’s potential to compete with conventional Wi-Fi has inspired the popular characterization Li-Fi.

A. Visible light communication (VLC)-“A potential solution to the global wireless spectrum shortage” 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).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 transmission and illumination. It uses fast pulses of light to transmit information wirelessly. The main components of this communication system are 1) A high brightness white LED, Which acts as a communication source and 2) A silicon photodiode which shows good response to visible wavelength region serving as the receiving element? LED can be switched on and off to generate digital strings of 1s and 0s. Data can be Encoded in the light to generate a new data stream by varying the flickering rate of the LED. To be clearer, by modulating the LED light with the data signal, the LED illumination can be used as a communication source. As the flickering rate is so Fast, the LED output appears constant to the human eye. A data rate of greater than 100 Mbps is possible by using high speed LEDs with appropriate multiplexing techniques. VLC data rate can be increased by parallel data transmission using LED arrays where each LED transmit a different data stream. There are reasons to prefer LED as the light source in VLC while a lot of other illumination devices like fluorescent lamp, incandescent bulb etc. are available. B.COMPARISION BETWEEN Li-Fi & Wi-Fi:


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LI-FI is a term of one used to describe visible light Communication technology applied to high speed wireless communication. It 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.

Speed Data density

Wireless(current) Wi-Fi-IEEE 802.11N

150Mbps *

Bluetooth 3Mnps * IrDA 4Mbps *** Wireless(future) WiGig 2Gbps ** Giga-IR 1Gbps *** Li-Fi >1Gbps ****

Table 1.Comparison between current and future wireless Technology

The table also contains the current wireless technologies that can be used for transferring data between devices today, i.e. Wi-Fi, Bluetooth and IrDA. Only Wi-Fi currently offers very high data rates. The IEEE 802.11.n in most implementations provides up to 150Mbit/s (in theory the standard can go to 600Mbit/s) although in practice you receive considerably less than this. Note that one out of three of these are an optical technology.

III How it is different?

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 of light, no matter the part of the spectrum that they belong. That is, the light can belong to the invisible, ultraviolet or the visible part of the spectrum. Also, the speed of the internet is incredibly high and you can download movies, games, music etc in just a few minutes with the help of this technology. Also, the technology removes limitations that have been put on the user by the Wi-Fi. You no more need to be in a region that is Wi-Fi enabled to have access to the internet. You can simply stand under any form of light and surf the internet as the connection is made in case of any light presence. There cannot be anything better than this technology.

IV. APPLICATION AREAS: Li Fi technology is still in its

infancy .However some areas where it seems perfectly applicable are:-

POTENTIAL APPLICATION OF LI-FI (A) Traffic Lights:

Traffic lights can communicate to the car and with each other. Cars have LED-based headlights, LED-based cack lights, and cars can communicate with each other and prevent accidents in by exchanging information


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. (B) Intrinsically Safe Environment:

Visible Light is safer than RF, hence it can be used in places where RF can't be used such as petrochemical plants

(C) Hospitals: LED is most preferably used in hospitals (In Few Medical Equipements)

(D) Airlines :

Whenever we travel through airways we face the problem in communication media, because the whole airways communications are performed on the basis of radio waves. To overcome this drawback on radio waves, Li-Fi is introduced.

4. On Ocean Beds :

Li-Fi can even wok underwater were Wi-Fi fails completely, thereby throwing open endless opportunities for military/navigation operations.

V. 'LI-FI’ VIA LED LIGHT BULB DATA SPEED BREAK

UK researchers say they have achieved data transmission speeds of 10Gbit/s via "li-fi" - wireless internet connectivity using light.

The researchers used a micro-LED light bulb to transmit 3.5Gbit/s via each of the three primary colours - red, green, blue - that make up white light.

This means over 10Gbit/s is possible. Li-fi is an emerging technology that could see specialised LED lights bulbs providing low-cost wireless internet connectivity almost everywhere.


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Micro-LEDs can transmit large amounts of digital data in parallel

(A) High speed The research, known as the ultra-parallel visible light communications project, is a joint venture between the universities of Edinburgh, St Andrews, Strathclyde, Oxford, and Cambridge, and funded by the Engineering and Physical Sciences Research Council.

The tiny micro-LED bulbs, developed by the University of Strathclyde, Glasgow, allow streams of light to be beamed in parallel, each multiplying the amount of data that can be transmitted at any one time.

"If you think of a shower head separating water out into parallel streams, that's how we can make light behave," said Prof Harald Haas, an expert in optical wireless communications at the University of Edinburgh and one of the project leaders.

Using a digital modulation technique called Orthogonal Frequency Divisional Multiplexing (OFDM), researchers enabled micro-LED light bulbs to handle millions of changes in light intensity per second, effectively behaving like an extremely fast on/off switch.

This allows large chunks of binary data - a series of ones and zeros - to be transmitted at high speed.

Earlier this year, Germany's Fraunhofer Heinrich Hertz Institute claimed that data rates of up to 1Gbit/s per LED light frequency were possible in laboratory conditions. And this month, Chinese scientists reportedly developed a microchipped LED bulb that can produce data speeds of up to 150 megabits per second (Mbps), with one bulb providing internet connectivity for four computers.

VI.. 'Light fidelity' Prof Harald Haas has been in the forefront of "Li-Fi" research for the last 10 years In 2011, Prof Haas demonstrated how an LED bulb equipped with signal processing technology could stream a high-definition video to a computer.

He coined the term "light fidelity" or Li-Fi - also known as visual light communications (VLC) - and set up a private company, Pure VLC, to exploit the technology.

Li-Fi promises to be cheaper and more energy-efficient than existing wireless radio systems given the ubiquity of LED bulbs and the fact that lighting infrastructure is already in place.

Visible light is part of the electromagnetic spectrum and its bandwidth is 10,000 times bigger than the radio frequency spectrum used by existing communication systems, affording vastly greater capacity. Another advantage, Prof Haas argues, is that evenly spaced LED transmitters could provide much more localised and consistent internet connectivity throughout buildings.


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The disadvantage of traditional Wi-Fi routers is that the signal weakens the further you are away from it, leading to inconsistent connectivity within offices and homes.

Prof Haas also believes light's inability to penetrate walls makes VLC technology potentially more secure than traditional Wi-Fi connectivity.

(A) LED light bulb 'Li-Fi' closer, say Chinese scientists

If "'Li-Fi' " technology takes off, all LED lights could potentially provide internet connectivity. Wi-Fi connectivity from a light bulb - or "'Li-Fi' " - has come a step closer, according to Chinese scientists. A micro chipped bulb can produce data speeds of up to 150 megabits per second (Mbps), Chi Nan, IT professor at Shanghai's Fudan University told Xinhua News.

A one-watt LED light bulb would be enough to provide net connectivity to four computers, researchers say. But experts told the BBC more evidence was needed to back up the claims. There are no supporting video or photos showing the technology in action.

Li-Fi, also known as visible light communications (VLC), at these speeds would be faster - and cheaper - than the average Chinese broadband connection.

In 2011, Prof Harald Haas, an expert in optical wireless communications at the University of

Edinburgh, demonstrated how an LED bulb equipped with signal processing technology could stream a high-definition video to a computer. He coined the term "light fidelity" or Li-Fi and set up a private company, Pure VLC, to exploit the technology.

"We're just as surprised as everyone else by this announcement," Pure VLC spokesman Nikola Serafimovski told the BBC.

"But how valid this is we don't know without seeing more evidence. We remain sceptical."

This year, the Fraunhofer Heinrich Hertz Institute claimed that data rates of up to 1Gbit/s per LED light frequency were possible in laboratory conditions, making one bulb with three colors potentially capable of transmitting data at up to 3Gbit/s.

Edinburgh University's Prof Harald Haas coined the

term "Li-Fi" (B) Unlimited capacity Li-Fi promises to be cheaper and more energy-efficient than existing wireless radio systems given the ubiquity of LED bulbs and the fact that lighting infrastructure is already in place.

Visible light is part of the electromagnetic spectrum and 10,000 times bigger than the radio spectrum,


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affording potentially unlimited capacity. But there are drawbacks: block the light and you block the signal. However, this is also a potential advantage from a security point of view. Light cannot penetrate walls as radio signals can, so drive-by hacking of wireless internet signals would be far more difficult, if not impossible.

Prof Chi's research team includes scientists from the Shanghai Institute of Technical Physics at the Chinese Academy of Sciences, the report says. She admitted that the technology was still in its infancy and needed further developments in microchip design and optical communication controls before it could go mass market.

Her team is hoping to show off sample li-fi kits at the China International Industry Fair in Shanghai on 5 November, the report said.

VII. LI-FI VS WIFI

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

Wi-Fi Uses The Radio wave Portion Of The EM

Li-Fi has a High speed data transfer rate over 1Gbps.{1024 Mbps}

Li-Fi Uses The Visible Light Portion Of The EM.

VIII. CONCLUSIONS

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.

We will proceed toward the cleaner, greener, safer and brighter future.

This may solve issues such as the shortage of radio-frequency bandwidth.

Allows internet where traditional radio based wireless isn’t allowed such as aircraft or hospitals.

REFERENCES [1] http://en.wikipedia.org/wiki/Li-Fi [2] http://www.scribd.com/doc/88377913/Synopsis-on-Lifi-The-

latesttechnology-in-wireless-communication. [3] http://www.scribd.com/doc/88340668/Seminar-Report-on-

LIFiTECHNOLOGY [4] seminarprojects.com/s/seminar-report-on-lifi [5] http://en.wikipedia.org/wiki/Li-Fi [6] http://teleinfobd.blogspot.in/2012/01/what-is-lifi.html [7] technopits.blogspot.comtechnology.cgap.org/2012/01/11/a-lifi-

world/www.lificonsortium.org/the-gadgeteer.com/2011/08/29/li-fi-internet-at-thespeed-of-light/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] http://www.digplanet.com/wiki/Li-Fi

4th [2015] college of computing sciences and information...

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