Light Fidelity ( Li-Fi ) Seminar Report

LIGHT FIDELITY

Shamil Ahammad K [Reg. No. 90012065]VIIth Semester B.Tech Instrumentation

Department of Instrumentation, Cochin University of Science & TechnologyCochin, Kerala, India -682022

ABSTRACT

Light Fidelity or Li-Fi is a Visible Light Communication technology developed by a team of scientists including Dr. Gordon Povey, Prof. Harald Haas and Mostafa Afgani at the University of Edinburgh. Li-Fi, as coined by Prof. Harald Haas during his TED Global talk, is a bidirectional, high speed and fully networked wireless communications similar to Wi-Fi. Li-Fi is a subset of optical wireless communications (OWC) and can be a complement to RF communication (Wi-Fi or Cellular network), or a replacement in contexts of data broadcasting. It is wireless and uses visible light communication or infra-red and near ultraviolet (instead of radio frequency waves) spectrum, part of Optical wireless communications technology, which carries much more information, and has been proposed as a solution to the RF-bandwidth limitations.

In a Wi-Fi hotspot, as more and more people and their many devices access wireless internet, we have probably gotten frustrated at the slow speeds. Prof. Harald Haas has come up with a solution he calls “data through illumination” –taking the fibber out of fiber optic by sending data through an LED light bulb that varies in intensity faster than the human eye can follow. It’s the same idea band behind infrared remote controls but far more powerful. Haas says his invention can produce data rates faster than 10 megabits per second, which is speedier than present average broadband connection. He envisions a future where data for laptops, smart phones, and tablets is transmitted through the light in a room. And security would be snap – if you can’t see the light, you can’t access the data.

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List of Contents

Introduction ……………………………………………...4

History …………………………………………………...6

Working Technology ……………………………………9

Li-Fi Transmitter .……………………………………….11

Li-Fi Receiver …………………………………………..12

Comparison between Wi-Fi and Li-Fi ………………….13

Present Scenario of Radio Waves ………………………14

Drawbacks of other Electromagnetic Spectrums …...…..15

How it is Different? …….………………………………16

Applications of Li-Fi …………………………………...17

UK Research Report ……………………………………21

Recent Updates …………………………………………23

Conclusion ……………………………………………...24

Reference ……………………………………………….25

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IntroductionLiFi 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 optical version of Wi-Fi. The term was first used in this context by Harald Haas in his TED Global talk on visible light communication. ‘’At the heart of his technology is a new generation of high brightness light-emitting diodes’’, says Harald Haas from the university of Edinburgh, UK, ‘’Very simply, if the LED is on, you transmit a digital 1, if it’s off you transmit a 0, ‘’Haas says, ‘’they can be switched on and off very quickly, which gives nice opportunities for transmitted data. ‘’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 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 Edinburgh are focusing on parallel data transmission using array 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 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 meters.

Light is inherently safe and can be used in places where radio frequency communication is often deemed problematic, such as in aircrafts 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.

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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 radiobased wireless 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.

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History

Professor Harald Haas, the University of Edinburgh in the UK, is widely recognized as the original founder of Li-Fi. He coined the term Li-Fi and is chair of Mobile Communications at the University of Edinburgh and co-founder of pure Li-Fi. The general term visible light communication (VLC), includes any use of the visible light portion of the electromagnetic spectrum to transmit information. The D-light at Edinburgh’s institute for Digital Communications was funded from January 2010 to January 2012. Haas promoted this technology in his 2011 TED Global talk and helped start a company to market it. Pure Li-Fi, formerly pure VLC, is an original equipment manufacturer (OEM) firm set up to commercialize Li-Fi product for integration with existing LED-lighting systems. In October 2011, companies and industry groups formed the Li-Fi consortium, to promote high speed optical wireless systems and to overcome the limited amount of radio-based wireless spectrum available by exploiting a completely different part of the electromagnetic spectrum. A number of companies offer uni-directional VLC products which is not the same as Li-Fi.

VLC technology was exhibited in 2012 using Li-Fi. By August 2013, data rates of over 1.6 Gbps were demonstrated over a single color LED. In September 2013, a press release said that, Li-Fi do not require line of sight conditions. In October 2013 Chinese manufactures were working on Li-Fi development kits. One part of VLC is modeled after communication protocols established by the IEEE work group. However, the IEEE 802.15.7 standard is out of date. Specifically the standard fails consider the latest technological developments in the field of optical wireless communications, specifically with the introduction of optical orthogonal frequency division multiplexing(O-OFDM) modulation methods which have been optimized for data rates, multiple-access and energy efficiency have. The introduction of O-OFDM means that a new drive for standardization of optical wireless communications is required.

Nonetheless the IEEE 802.15.7 standard defines the physical layer (PHY) and media access control (MAC) layer. The standard is able to deliver enough data

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rates to transmit radio, video and multimedia services. It takes into account the optical transmission mobility, its compatibility with artificial lightning present in infrastructures, the deviance which may be caused by interference generated by the ambient lightning. The MAC layer allows to use the link with the other layers like the TCP/IP protocol.

The standards define three PHY layers with the different rates:

PHY I : Outdoor Applications from 11.66 Kbps to 267.6 Kbps PHY II : Allows Speed from 1.25 Mbps to 96 Mbps PHY III : Used For Color Shift Keying delivers speed from 12 Mbps to

96 Mbps

The modulation formats reorganized for PHY I and PHY II are the coding ON-OFF keying (OOK) and variable pulse position modulation (VPPM). The Manchester coding used for the PHY I and PHY II layers include the clock inside the transmitted data by representing a logic 0 with an OOK symbol ‘01’ and a logic 1 with an OOK symbol ‘10’, all with a DC component. The DC component avoids the light extinction in case of an extended lie of logic 0.

The first LiFi smartphones prototype was presented at the Consumer Electronics Show in Las Vegas from January 7 – 10 in 2014. The phone uses Sun Partners Wysips CONNECT, a technique that converts light waves into usable energy, making the phone capable of receiving and decoding signals without drawing on its battery.

LiFi refers to 5G VLC systems using light connection from LEDs as a medium to deliver networked, mobile, high speed communication in a similar manner as WiFi. LiFi could lead to the Internet Of Things, which is everything electronics being connected to internet, with the LED lights on the electronics being used as internet as access points. The LiFi market is projected to have a compound of 82% from 2013 to 2018 and to be worth over $6 billion per year by 2018.

VLC signals work by switching bulbs on and off within nanoseconds, which is too quickly to be noticed by the human eye. Although LiFi 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. The light waves cannot

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penetrate walls which makes a short range, though more secure from hacking, relating to WiFi. Direct line of sight isn’t necessary for LiFi transmit signal and light reflected off of the walls can achieve 70 Mbps.

LiFi has the advantage of being able to be used in electromagnetic sensitive areas such as in aircraft cabins, hospitals and nuclear power plants without causing electromagnetic interference. Both LiFi and WiFi transmit data over the electromagnetic spectrum, but whereas WiFi utilizes radio waves, LiFi uses visible light. While the Federal Communications Commision has warned of a potential spectrum crisis because Wifi is close to full capacity, LiFI has almost no limitations on capacity. The VLC is 10,000 times larger than the entire radio frequency spectrum. Researchers have reached the data rates over 10Gbps. LiFi is expected to be 10 times cheaper and more environmentally friendly than WiFi. Short range, low reliability and high installation costs are the potential downsides.

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Working Technology

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 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

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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 LiFi.

Visible light communication (VLC)-“A potential solution to the global wireless spectrum shortage”

LiFi (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 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 transmits 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.

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Li-Fi Transmitter

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, say Chinese scientist. A microchipped bulb can produce data speeds of upto 150Mbps, Chinan, IT professor at Shanghai’s Fudan University told Xinhua News.

LiFi is a new class of high intensity light source of solid state design bringing clean lightning solutions to general and specialty lightning with energy efficiency, long useful lifetime, full spectrum and dimming.

Four primary sub-assemblies

Bulb RF power amplifier circuit PCB Enclosure

The PCB controls the electrical inputs and outputs of the lamp ad houses the microcontroller used to manage different lamp function. An RF 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 of the bulb to a plasma generates an intense source of light. All of these subassemblies are contained in an aluminum enclosure.

Function of the Bulb Sub Assembly

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 wave guide for the RF energy transmitted by the RF-Power Amplifier and second as an electric field concentrates that focuses energy in the bulb. The energy from the electric field rapidly heats the material in the bulb to plasma state that emits light of high intensity and full spectrum.

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Li-Fi Receiver

Figure of Data transmission using LED

The figure illustrates a main server connecting the internet is transmitted over visible light transmitter Li-Fi LED lamp, which collects at receiving end, by photodiode and decoded, amplified and transmit to the computer.

Basic Li-FI receiver is of a photodiode which collect incoming visible lights which are tuned for certain intensities produce signals that can be demodulated or decoded by a Li-Fi modem or router.

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Present Scenario of Radio WavesCapacity

Now datas are transmitted over radio waves. Radio waves are limited and little scare and very expensive to set up the base stations and other things. Considering the capacity of radio waves it has only limited certain range. With the advent of 2.5G, 3G and 4G new generation technologies, we are running out of spectrum.

Efficiency

There are 1.4 million cellular radio base stations all over the world. These cellular towers and base stations consumes massive amount of energy, and most of the energy used for cooling down the systems. Efficiency of such base stations are less than ten percent.

Availability

We have to switch off our mobile phones in most of the airplanes. In mid sea the availability is almost zero. Radio wave communication inside or near the power plants and petrol pumps are banned or limited. Most of the petroleum

companies has banned usage of mobile phones inside the company.

Security

Radio waves penetrate through walls, is an advantage. But in some cases regarding the security issues, they can be intercepted. If someone has

knowledge and bad intentions, he may misuse it.

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Drawbacks of other Electromagnetic Spectrum

Gamma rays are simply very dangerous and thus can’t be used for our

purpose of communication.

X-Rays are good in hospital and can’t be used either

UV rays in long duration is dangerous

IR increases heat and can’t be used in high powers

Radio waves are short in bandwidth, not environmental

Visible light are faster, large bandwidths, secure, environmental.

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Comparison Between Li-Fi & Wi-Fi

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.

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 is an optical technology.

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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.

Figure Shows Basic Working and advantages

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Applications OF Li-Fi

You Might Just Live Longer

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 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, delegate red light to priority medical data. Code Red!

Airlines

Airline Wi-Fi, Nothing says captive audience likes having to pay for the "service" of dial-up speed Wi-Fi on the plane. And don’t get started on the pricing. The best have heard 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. Uh, we have twice that capacity in our living room. And at the same price as checking a bag, we expect it. 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

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Undersea Awesomeness

Underwater ROVs, those favorite toys of treasure seekers and James Cameron, operate from large cables that supply their power and allow them to receive signals from their pilots above. ROVs work great, except when the tether isn’t long enough to explore an area, or when it gets stuck on something. If their wires were cut and replaced with light — say from a submerged, high-powered lamp — then they would be much freer to explore. They could also use their headlamps to communicate with each other, processing data autonomously and referring findings periodically back to the surface, all the while obtaining their next batch of orders.

It Could Keep You Informed and Save Lives

Say there’s an earthquake in somewhere or a thunder storm. The average people may not know what the protocols are for those kinds of disasters. Until they pass under a street light, that is. Remember, with Li-Fi, if there’s light, you’re online. Subway stations and tunnels, common dead zones for most emergency communications, pose no obstruction. Plus, in times less stressing cities could opt to provide cheap high-speed Web access to every street corner.

Uses In Various Areas

Can be used in the places where it is difficult to lay the optical fiber like hospitals. In operation theatre LiFi can be used for modern medical instruments. In traffic signals LiFi can be used which will communicate with the LED lights of the cars and accident numbers can be decreased. Thousand and millions of street lamps can be transferred to LiFi lamps to transfer data. In aircraft LiFi can be used for data transmission. It can be used in petroleum or chemical plants where other transmission or frequencies could be hazardous.

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 TED Global conference in Edinburgh on 12 th 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

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periodically blocked the light from lamp to prove that the lamp was indeed the source of incoming data. At TED Global, Haas demonstrated a data rate of transmission of around 10Mbps-comparable to a fairly good UK broadband connection. Two months later he achieved 123Mbps.

Green Information Technology

It means , unlike radio waves and other communication waves affects on birds, human bodies etc.. Li-Fi never gives such kind of side effects on any living thing.

Communication Safety

Due to visual light communication, the node or any terminal attach to our network is visible to the host of network. So we can take this as a an advantage of Li-Fi in case of securities.

Multi User Communication

Li-Fi supports the broadcasting of the networks, it helps to share multiple thing at a single instance called broadcasting. Using more connections in a single network does not make large problems as like we connecting in a Wi-Fi network.

Hotspots of Lighting Points

Any lighting device is performed as a hotspot it means that the light device like car lights, ceiling lights, street lamps etc are area able to spread internet connectivity using visual light communication. This helps us to low cost architecture for hotspot. Hotspot is a limited region in which some amount of device can access data through internet connectivity.

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Block Diagram of Li-Fi Internet Connectivity

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. To further get a grasp of Li-Fi consider an IR remote. It sends a single data of bits at the rate of 10000-20000 bps. Now replace the IR LED with a Light Box containing a large LED array.

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UK Research Report

UK researchers said they have achieved data transmission speeds of 10Gbps via LiFi. The researchers used a micro-LED light bulb to transmit 3.5Gbps via each of the three primary colors – Red, Green and Blue – that make white light. This means over 10Gbps is possible. LiFi is an emerging technology that could see specialized LED lights bulbs providing low cost internet connectivity almost everywhere.

Li-Fi Data Delivery Rates

The research known as the ultra-parallel visible light communication project, is a joint venture between the universities of Edinburgh, St Andrews, Starthclyde, Oxford and Cambridge, and funded by the Engineering and Physical Sciences Research Council.

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

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“ If you think of a shower head separating water out into parallel streams, that’s how we can make light behave “ said the Prof. Harald Haas.

Using Orthogonal Frequency Divisional Multiplexing (OFDM), researchers enabled micro LED bulbs to handle millions of changes in light intensity per second, effectively behaving like an extremely fast ON-OFF switch. This enables large chunks of binary data- a series of ones and zeroes- to be transmitted at high speed.

Earlier this year, Germany’s Fraunhofer Heinrich Hertz Institute claimed that data rates up to 1Gbps per LED light frequency were possible in laboratory conditions. Chinese scientists reportedly developed a microchipped LED bulb that can produce data up to 150Mbps with one bulb providing internet connectivity for four computers.

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Recent Updates

Prof. Harald Haas has been in forefront of Li-Fi research for more than ten years. In 2011 he demonstrated how an LED bulb equipped with the signal processing technology could stream a HD Video to a computer.

His Li-Fi company called pureLiFiTM introduced two new products this year in market which works fine with high speed data communication. These home devices can achieve capacity of data transmission rate at more than 1Gbps, which can stream high definition 3D, 4K videos without any stuck or clarity loss.

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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 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 work in direct line of sight.

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Reference

[1] Prof. Harald Haas’s pureLiFi project website, www.purelifi.com

[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] Will Li-Fi be the new Wi-Fi?, Scientist Jamie Condliffe, 28 July 2011

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

[12] ”Visible-light communication: Tripping the light fantastic: A fast and cheap optical version of Wi-Fi is coming”, Economist, dated 28Jan 2012

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