Li-Fi (Light Fidelity) The future technology In Wireless communication
ABSTRACT 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 have 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 germen phycist.Harald Haas has come up with a solution he calls data through illumination! illumination! "taking the fibber out of fiber optic by sending data through an #$% light bulb that varies in intensity faster than the human eye can follow. &t’s the same idea band behind infrared remote controls but far more powerful. Haas says his invention, which he calls %#&'H(, can produce data rates faster than )* megabits persecond, which is speedier than your average broadband connection. He envisions a future where data for laptops, smart phones, and tablets is transmitted through throu gh the light lig ht in aroom. aroo m. And security would be snap " if you can’t see the light, you can’t access the data. #i+i is a -#, visible light communication, technology developed by a team of scientists including %r 'ordon /ovey, /rof. Harald Haas and %r 0ostafa Afgani at the 1niversity of $dinburgh. (he term #i+i was coined by /rof. Haas when he ama2ed people by streaming high+definition video from a standard #$% lamp, at ($% 'lobal in 3uly 4*)). #i+i is now part of the -isible -isible #ight ommunications 5-#6 /A7 /A7 &$$$ 8*4.)9.: standard. #i+i is typically implemented using white #$% light bulbs. (hese devices are normally used for illumination by applying a constant current through the #$%. However, by fast and subtle variations of the current, the optical output can be made to vary at extremely high speeds. 1nseen by the human eye, this variation is used to carry high+speed data,! says %r /ovey, , /roduct 0anager of the 1niversity of $dinburgh;s #i+i /rogram <%+#ight /ro=ect’.
ITR!"#CTI! #ii is transmission of data through illumination by taking the fiber out of fiber optics by sending data through a #$% light lig ht bulb that varies in intensity faster than the human eye can can foll follow ow..#i+ #i+ii is the the term term some some have have used used to labe labell the the fast fast and and chea cheap p wire wirele less ss communication system, which is the optical version of Wi+i. (he term was first used in this context by Harald Haas in his ($% 'lobal talk on -isible #ight ommunication. At the heart of this technology is a new generation of high brightness light+emitting diodes!, says Harald Haas from the 1niversity of $dinburgh, 1>,!-ery simply, if the #$% is on, you transmit a digital ), if it’s off you transmit a *,!Haas *,!Haas says, (hey can be switched on and off very ?uickly, which gives nice opportunities for transmitted data.!&t is possible to encode data in the light by varying the rate at which the #$%s flicker on and off to give different strings of )s and *s.(he #$% intensity intensity is modulated so rapidly that human eye cannot notice, so the output appears constant. 0ore sophisticated techni?ues could dramatically increase -# data rate. (erms at the 1niversity of Oxford and the 1niversity of $dingburgh are focusing on parallel data transmission using array of #$%s, where each #$% transmits a different data stream stream.. Other Other group group are using using mixtu mixtures res of red,gr red,gree een n and blue #$%s #$%s to alte alterr the the light light fre?ue fre?uency ncy encodi encoding ng a diffe differen rentt data data channe channel. l.#i #i+ +i, i, as it has been been dub dubbe bed, d, has has alrea already dy achieved blisteringly high speed in the lab. @esearchers at the Heinrich Hert2 &nstitute in erlin,'ermany erlin,'ermany,, have reached data rates of over 9** megabytes megabytes per second using a standard white+light white+light #$%. (he technology was demonstrated at the 4*)4 onsumer $lectronics Bhow in #as -egas using a pair ofasio smart phones to exchange data using light of varying intensity given off from their screens, detectable at a distance of up to ten metres. #ight is inherently safe and can be used in places where radio fre?uency communication is ofte often n deem deemed ed prob proble lema mati tic, c, such such as in airc aircra raft ft cabi cabins ns or hosp hospit ital als. s. Bo visi visibl blee ligh lightt communication not only has the potential to solve the problem of lack of spectrum space, but can also enable novel application. (he visible light spectrum is unusedC it;s not regulated, and can be used for communication at very high speeds.
ig.) #i+i environment
&n October 4*)) a number of companies and industry groups formed the #i+i onsortium, 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. (he consortium believes it is possible to achieve more than )* 'bps, theoretically allowing a high+definition film to be downloaded in D* seconds.
W!R$I% T&C'!L!% (his brilliant idea was first showcased by Harald Haas from 1niversity of $dinburgh, 1>, in his ($% 'lobal talk on -#. He explained,! -ery simple, if the #$% is on, you transmit a digital ), if it’s off you transmit a *. (he #$%s can be switched on and off very ?uickly, which gives nice opportunities for transmitting data.! Bo what you re?uire at all are some #$%s and a controller that code data into those #$%s. We have to =ust vary the rate at which the #$%’s flicker depending upon the data we want to encode. urther enhancements can be made in this method, like using an array of #$%s for parallel data transmission, or using mixtures of red, green and blue #$%s to alter the light’s fre?uency with each fre?uency encoding a different data channel. Buch advancements promise a theoretical speed of )* 'bps " meaning you can download a full high+definition film in =ust D* seconds. Bimply awesomeE ut bla2ingly fast data rates and depleting bandwidths worldwide are not the only reasons that give this technology an upper hand. Bince #i+i uses =ust the light, it can be used safely in aircrafts and hospitals that are prone to interference from radio waves. (his can even workunderwater where Wi+i fails completely, thereby throwing open endless opportunities for military operations. &magine only needing to hover under a street lamp to get public internet access, or downloading a movie from the lamp on your desk. (here;s a new technology on the block which could, ?uite literally as well as metaphorically, ;throw light on; how to meet the ever+ increasing demand for high+speed wireless connectivity. @adio waves are replaced by light waves in a new method of data transmission which is being called #i+i.#ight+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. #ight+emitting diodes 5commonly referred to as #$%s and found in traffic and street lights, car brake lights, remote control units and countless other applications6 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;. (his invisible on+off activity enables a kind of data transmission using binary codesF switching on an #$% is a logical ;);, switching it off is a logical ;*;. &nformation cantherefore be encoded in the light by varying the rate at which the #$%s flicker on and off to give different strings of )s and *s.
isi*le light communication (LC)-+A ,otential solutionto the glo*al ireless s,ectrum shortage. #ii 5#ight idelity6 is a fast and cheap optical version of Wi+i, the technology of which is based on -isible #ight ommunication 5-#6.-# is a data communication medium, which uses visible light between G** (H2 5:8* nm6 and 8** (H2 5D:9 nm6 as optical carrier for data transmission and illumination. &t uses fast pulses of light to transmit information wirelessly. (he main components of this communication system are )6 a high brightness white #$%, Which acts as a communication source and 46 a silicon photodiode which shows good response to visible wavelength region serving as the receiving element #$% can be switched on and off to generate digital strings of )s and *s. %ata can be encoded in the light to generate a new data stream by varying the flickering rate of the #$%. (o be clearer, by modulating the #$% light with the data signal, the #$% illumination can be used as a communication source. As the flickering rate is sofast, the #$% output appears constant to the human eye. A data rate of greater than )** 0bps is possible by using high speed #$%s with appropriate multiplexing techni?ues. -#. data rate can be increased by parallel data transmission using #$% arrays where each #$% transmits a different data stream. (here are reasons to prefer #$% as the light source in -# while a lot of other illumination devices like fluorescent lamp, incandescent bulb etc. are available.
ig 4.%ata transmission using #
%$ C!/0ARISI! B&TW&& Li-Fi 1 Wi-Fi #&+& is a term of one used to describe visible light communication technology applied to high speed wireless communication. &t ac?uired this name due to the similarity to W&+&, only using light instead of radio.W&+& 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.
(able ).omparison between current and future wireless technology
(he table also contains the current wireless technologies that can be used for transferring data between devices today, i.e. Wi+i, luetooth and &r%A.Only Wi+i currently offers very high data rates. (he &$$$ 8*4.)).n in most implementations provides up to )9*0bitIs 5in theory the standard can go to J**0bitIs6 although in practice you receive considerably less than this. 7ote that one out of three of these is an optical technology.
'o it is different2 #i+i technology is based on #$%s for the transfer of data. (he transfer of the data can be with the help of all kinds of light, no matter the part of the spectrum that they belong. (hat is, the light can belong to the invisible, ultraviolet or the visible part of the spectrum. Also, the speed of the internet is incredibly high and you can download movies, games, music etc in =ust a few minutes with the help of this technology. Also, the technology removes limitations that have been put on the user by the Wi+i. Kou no more need to be in a region that is Wi+i enabled to have access to the internet. Kou can simply stand under any form of light and surf the internet as the connection is made in case of any light presence. (here cannot be anything better than this technology.
ig D.Working and advantages
A00LICATI! !F LI-FI ou /ight 3ust Li4e Longer or a long time, medical technology has lagged behind the rest of the wireless world. Operating rooms do not allow Wi+i over radiation concerns, and there is also that whole lack of dedicated spectrum. While Wi+i is in place in many hospitals, interference from cell phones and computers can block signals from monitoring e?uipment. #i+i solves both problemsF lights are not only allowed in operating rooms, but tend to be the most glaring 5pun intended6 fixtures in the room. And, as Haas mentions in his ($% (alk 5 #i+i has )*,*** times the spectrum of Wi+i, so maybe we can, & don’t know, delegate red light to priority medical data. ode @edE
Airlines6 Airline Wi+i. 1gh. 7othing says captive audience like having to pay for the LserviceL of dial+up speed Wi+i on the plane. And don’t get me started on the pricing. (he best &’ve heard so far is that passengers will LsoonL be offered a Lhigh+speed likeL connection on some airlines. 1nited is planning on speeds as high as 789 /*,s per plane. 1h, & have twice that capacity in my living room. And at the same price as checking a bag, & expect it. #i+i could easily introduce that sort of speed to each seat;s reading light. &’ll be the guy wowing next to you. &t’s better than listening to you tell me about your wildly successful son, ma’am.
Smarter 0oer 0lants6 Wi+i and many other radiation types are bad for sensitive areas. #ike those surrounding power plants. ut power plants need fast, inter+connected data systems to monitor things like demand, grid integrity and 5in nuclear plants6 core temperature. (he savings from proper monitoring at a single power plant can add up to hundreds of thousands of dollars. #i+i could offer safe, abundant connectivity for all areas of these sensitive locations. 7ot 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 #$% lighting.
#ndersea Aesomeness6
1nderwater @O-s, those favorite toys of treasure seekers and 3ames ameron, operate from large cables that supply their power and allow them to receive signals from their pilots above. @O-s work great, except when the tether isn’t long enough to explore an area, or when it gets stuck on something. &f their wires were cut and replaced with light M say from a submerged, high+powered lamp M then they would be much freer to explore. (hey 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 $ee, ou Informed and Sa4e Li4es Bay there’s an earth?uake in 7ew Kork. Or a hurricane. (ake your pick M it’s a wacky city. (he average 7ew Korker may not know what the protocols are for those kinds of disasters. 1ntil they pass under a street light, that is. @emember, with #i+i, if there’s light, you’re online. Bubway stations and tunnels, common dead 2ones for most emergency communications, pose no obstruction. /lus, in times less stressing cities could opt to provide cheap high+speed Web access to every street corner.
#S&S I ARI!#S AR&AS an be used in the places where it is difficult to lay the optical fiber like hospitals. &n operation theatre #ii can be used for modern medical instruments. &n traffic signals #ii can be used which will communicate with the #$% lights of the cars and accident numbers can be decreased. (housand and millions of street lamps can be transferred to #ii lamps to transfer data. &n aircraft #ii can be used for data transmission. &t can be used in petroleum or chemical plants where other transmission or fre?uencies could be ha2ardous.
%enesis of LI-FI6 Harald Haas, a professor at the 1niversity of $dinburgh who began his research in the field in 4**G, gave a debut demonstration of what he called a #i+i prototype at the ($% 'lobal conference in $dinburgh on )4th 3uly 4*)). He used a table lamp with an #$% bulb to transmit a video of blooming flowers that was then pro=ected onto a screen behind him. %uring the event he periodically blocked the light from lamp to prove that the lamp was indeed the source of incoming data. At ($% 'lobal, Haas demonstrated a data rate of transmission of around )*0bps ++ comparable to a fairly good 1> broadband connection. (wo months later he achieved )4D0bps.
'o it is different2 #i+i technology is based on #$%s for the transfer of data.(he transfer of the data can be with the help of all kinds oflight, no matter the part of the spectrum that they belong. (hatis,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, music etc in =ust a few minutes with the help of this technology.
Also, the technology removes limitations that have been puton the user by the Wi+i. Kou no more need to be in a regionthat is Wi+i enabled to have access to the internet. Kou cansimply stand under any form of light and surf the internet asthe connection is made in case of any light
presence.
(herecannot
be
anything
better
than
this
technology.
(o further get a grasp of #i+i consider an &@ remote. &t sends a single data stream of bits at the rate of )*,***+4*,*** bps. 7ow replace the &@ #$% with a #ight ox containing a large #$% array.
'IST!R /rofessor Harald Haas, from the 1niversity of $dinburgh in the 1>, is widely recognised as the original founder of #i+i. He coined the term #i+i and is hair of 0obile ommunications at the 1niversity of $dinburgh and co+founder of pure#ii. (he general term visible light communication 5-#6, includes any use of the visible light portion of the electromagnetic spectrum to transmit information. (he %+#ight pro=ect at $dinburgh;s &nstitute for %igital ommunications was funded from 3anuary 4*)* to 3anuary 4*)4. Haas promoted this technology in his 4*))($% 'lobal talk and helped start a company to market it. /ure#ii, formerly pure-#, is an original e?uipment manufacturer 5O$06 firm set up to commerciali2e #i+i products for integration with existing #$%+lighting systems. &n October 4*)), companies and industry groups formed the #i+i onsortium, 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 -# products which is not the same as #i+i. -# technology was exhibited in 4*)4 using #i+i. y August 4*)D, data rates of over ).J 'bps were demonstrated over a single color #$%. &n Beptember 4*)D, a press release said that #i+i, or -# systems in general, do not re?uire line+of+sight conditions. &n October 4*)D, it was reported hinese manufacturers were working on #i+i development kits. One
part
of
-#
is
modeled
after
communication
protocols
established
by
the &$$$ workgroup. However, the &$$$ 8*4.)9.: standard is out+of+date. Bpecifically, the standard fails to consider the latest technological developments in the field of optical wireless communications, specifically with the introduction of optical orthogonal fre?uency+division multiplexing 5O+O%06 modulation methods which have been optimi2ed for data rates, multiple+access and energy efficiency have. (he introduction of O+O%0 means that a new drive for standardi2ation of optical wireless communications is re?uired. 7onetheless, the &$$$ 8*4.)9.: standard defines the physical layer 5/HK6 and media access control 50A6 layer. (he standard is able to deliver enough data rates to transmit audio, video and multimedia services. &t takes into account the optical transmission mobility, its compatibility with artificial lighting present in infrastructures, the devience which may be
caused by interference generated by the ambient lighting. (he 0A layer allows to use the link with the other layers like the (/I&/ protocol. (he standard defines three /HK layers with different ratesF •
(he /HK & was established for outdoor application and works from )).J: kbitIs to 4J:.J kbitIs.
•
(he /HK && layer allows to reach data rates from ).49 0bitIs to NJ 0bitIs.
•
(he /HK &&& is used for many emissions sources with a particular modulation method called color shift keying 5B>6. /HK &&& can deliver rates from )4 0bitIs to NJ 0bitIs.
(he modulation formatsrecogni2ed for /HK & and /HK && are the coding on+off keying 5OO>6 and variable pulse position modulation 5-//06. (he 0anchester coding used for the /HK & and /HK && layers include the clock inside the transmitted data by representing a logic * with an OO> symbol L*)L and a logic ) with an OO> symbol L)*L, all with a % component. (he % component avoids the light extinction in case of an extended line of logic *. (he first #i+i smartphone prototype was presented at the onsumer $lectronics Bhow in #as -egas from 3anuary :")* in 4*)G. (he phone uses Bun /artner’s Wysips O77$(, a techni?ue that converts light waves into usable energy, making the phone capable of receiving and decoding signals without drawing on its battery.
Li-Fi, or light fidelity, refers to 9' visible light communication systems using light
from light+emitting diodes 5#$%s6 as a medium to deliver networked, mobile, high+speed communication in a similar manner as Wi+i. #i+i could lead to the &nternet of (hings, which is everything electronic being connected to the internet, with the #$% lights on the electronics being used as internet access points. (he #i+i market is pro=ected to have a compound of 84 from 4*)D to 4*)8 and to be worth over PJ billion per year by 4*)8. -isible light communications 5-#6 signals work by switching bulbs on and off within nanoseconds, which is too ?uickly to be noticed by the human eye. Although #i+i 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. (he light waves cannot penetrate walls which makes a much shorter range, though more secure from hacking, relative to Wi+ i. %irect line of sight isn;t necessary for #i+i to transmit signal and light reflected off of the walls can achieve :* 0bps.
#i+i has the advantage of being able to be used in electromagnetic sensitive areas such as in aircraft cabins, hospitals and nuclear power plantsQcitation causing electromagnetic
interference. oth
Wi+i
and
#i+i
transmit
needed R
without
data
over
the electromagnetic spectrum, but whereas Wi+i utilises radio waves, #i+i uses visible light. While the 1B ederal ommunications ommission has warned of a potential spectrum crisis because Wi+i is close to full capacity, #i+i has almost no limitations on capacity. (he visible
light
spectrum
is
)*,***
times
larger
than
the
entire radio
fre?uency spectrum.@esearchers have reached data rates of over )* 'bps, which is more than 49* times faster than superfast broadband.
:Li-fi: 4ia L&" light *ul* data s,eed *rea;through
#$ researchers say they ha4e achie4ed data transmission s,eeds of <=%*it>s 4ia ?li-fi? ireless internet connecti4ity using light8
(he researchers used a micro+#$% light bulb to transmit D.9'bitIs via each of the three primary colours + red, green, blue + that make up white light. (his means over )*'bitIs is possible.#i+fi is an emerging technology that could see specialised #$% lights bulbs providing low+cost wireless internet connectivity almost everywhere.
0icro+#$%s can transmit large amounts of digital data in parallel
'igh s,eed
(he research, known as the ultra-,arallel 4isi*le light communications ,ro@ect , is a =oint venture between the universities of $dinburgh, Bt Andrews, Btrathclyde, Oxford, and ambridge, and funded by the $ngineering and /hysical Bciences @esearch ouncil. (he tiny micro+#$% bulbs, developed by the 1niversity of Btrathclyde, 'lasgow, allow streams of light to be beamed in parallel, each multiplying the amount of data that can be transmitted at any one time. L&f you think of a shower head separating water out into parallel streams, that;s how we can make light behave,L said /rof Harald Haas, an expert in optical wireless communications at the 1niversity of $dinburgh and one of the pro=ect leaders. 1sing a digital modulation techni?ue called Orthogonal re?uency %ivisional 0ultiplexing 5O%06, researchers enabled micro+#$% light bulbs to handle millions of changes in light intensity per second, effectively behaving like an extremely fast onIoff switch. (his allows large chunks of binary data + a series of ones and 2eros + to be transmitted at high speed. $arlier this year, 'ermany;s raunhofer Heinrich Hert2 &nstitute claimed that data rates of up to )'bitIs per #$% light fre?uency were possible in laboratory conditions.And this month, hinese scientists reportedly developed a microchipped #$% bulb that can produce data speeds of up to )9* megabits per second 50bps6, with one bulb providing internet connectivity for four computers.
:Light fidelity:
/rof Harald Haas has been in the forefront of Lli+fiL research for the last )* years &n 4*)), 0rof 'aas demonstrated how an #$% bulb e?uipped with signal processing technology could stream a high+definition video to a computer. He coined the term Llight fidelityL or li+fi + also known as visual light communications 5-#6 + and set up a private company, /ure-#, to exploit the technology. #i+fi promises to be cheaper and more energy+efficient than existing wireless radio systems given the ubi?uity of #$% bulbs and the fact that lighting infrastructure is already in place.
-isible light is part of the electromagnetic spectrum and its bandwidth is )*,*** times bigger than the radio fre?uency spectrum used by existing communication systems, affording vastly greater capacity.Another advantage, /rof Haas argues, is that evenly spaced #$% transmitters could provide much more localised and consistent internet connectivity throughout buildings.
(he 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. /rof Haas also believes light;s inability to penetrate walls makes -# technology potentially more secure than traditional wi+fi connectivity.
LED light bulb 'li-f' closer, say Chinese scientists
&f Lli+fiL technology takes off, all #$% lights could potentially provide internet connectivity. Wi-fi connecti4ity from a light *ul* - or ?li-fi? - has come a ste, closer5 according to Chinese scientists8
A microchipped bulb can produce data speeds of up to )9* megabits per second 50bps6, hi 7an, &( professor at Bhanghai;s udan 1niversity told inhua es.
A one+watt #$% light bulb would be enough to provide net connectivity to four computers, researchers say.ut experts told the more evidence was needed to back up the claims.(here are no supporting video or photos showing the technology in action. #i+fi, also known as visible light communications 5-#6, at these speeds would be faster + and cheaper + than the average hinese broadband connection. &n 4*)), /rof Harald Haas, an expert in optical wireless communications at the 1niversity of $dinburgh, demonstrated how an #$% bulb e?uipped with signal processing technology could stream a high+definition video to a computer.He coined the term Llight fidelityL or li+fi and set up a private company, /ure-#, to exploit the technology.
LWe;re =ust as surprised as everyone else by this announcement,L /ure-# spokesman 7ikola Berafimovski told the . Lut how valid this is we don;t know without seeing more evidence. We remain sceptical.L (his year, the raunhofer Heinrich Hert2 &nstitute claimed that data rates of up to )'bitIs per #$% light fre?uency were possible in laboratory conditions, making one bulb with three colours potentially capable of transmitting data at up to D'bitIs.
$dinburgh 1niversity;s /rof Harald Haas coined the term Lli+fiL
#nlimited ca,acity #i+fi promises to be cheaper and more energy+efficient than existing wireless radio systems given the ubi?uity of #$% bulbs and the fact that lighting infrastructure is already in place. -isible light is part of the electromagnetic spectrum and )*,*** times bigger than the radio spectrum, affording potentially unlimited capacity.ut there are drawbacksF block the light and you block the signal.However, this is also a potential advantage from a security point of view. #ight cannot penetrate walls as radio signals can, so drive+by hacking of wireless internet signals would be far more difficult, if not impossible. /rof hi;s research team includes scientists from the Bhanghai &nstitute of (echnical /hysics at the hinese Academy of Bciences, the report says.Bhe 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 hina &nternational &ndustry air in Bhanghai on 9 7ovember, the report said.
'o LIFI Light Sources Wor;
ITR!"#CTI! #&& is a new class of high intensity light source of solid state design bringing clean lighting solutions togeneral and specialty lighting. With energy efficiency, long useful lifetime, full spectrum and dimming, #&& lighting applications work better compared to conventional approaches. (his technology briefdescribes the general construction of #&& lighting systems and the basic technology building blocksbehind their function.
LIFI C!STR#CTI! (he #&& product consists of G primary sub+assembliesF S ulb S @ power amplifier circuit 5/A6 S /rinted circuit board 5/6 S $nclosure (he / controls the electrical inputs and outputs of the lamp andhouses the microcontroller used to manage different lamp functions.An @ 5radio+fre?uency6 signal is generated by the solid+state /Aand is guided into an electric field about the bulb. (he highconcentration of energy in the electric field vapori2es the contentsof the bulb to a plasma state at the bulb’s centerC this controlledplasma generates an intense source of light. All of these subassemblies are contained in an aluminum enclosure.
F#CTI! !F T'& B#LB S#B-ASS&/BL At the heart of #&& is the bulb sub+assembly where a sealed bulb isembedded in a dielectric material. (his design is more reliable thanconventional light sources that insert degradable electrodes into thebulb. (he dielectric material serves two purposesC first as awaveguide for
the @ energy transmitted by the /A and second as anelectric field concentrator that focuses energy in the bulb. (heenergy from the electric field rapidly heats the material in the bulb toa plasma state that emits light of high intensity and full spectrum. (he #&& product consists of G primary sub+assembliesF S ulb S @ power amplifier circuit 5/A6 S /rinted circuit board 5/6 S $nclosure
(he / controls the electrical inputs and outputs of the lamp and houses the micro+ controller used to manage different lamp functions.
A,,lication of LiFi (Light Fidelity) Technology #i+i found its application in Airays5 %reen information technology5 multi user communication5 #nderater R! etc. and has many advantages which are discussed in
this pro=ect report. 1se this report on #ii only for your study and reference purpose.
(he design and construction of the #&& light source enable efficiency, long stable life, full spectrum intensity that is digitally controlled and easy to use.
/@$B$7( B$7A@&OF
We have ).G million cellular radio waves base stations deployed. We also have over 9 billions of mobile phones. 0obile phone transmits more than J**(b of data. Wireless communication has become a utility like electricity T water. We use it in everyday life,in our private life,business life.
urrently wifi uses @adio waves for communication.
&t is important to look into this technology which has become fundamental to our
life.
our &ssues with @adio WavesF ). apacityF
•
We transmit wireless data through radiowaves. @adio waves are limited,scar and expensive. We only have a certain range of it.
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With the advent of the new generation technologies as of
• •
likes of 4.9',D',G' and so on we are running out of spectrum.
4. $fficiencyF
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(here are ).G million cellular radio base stations. (hey consume massive amount of energy. 0ost of this energy is not used for transmission but for
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cooling down the base stations. $fficiency of such a base station is only 9 and that
• •
raise a very big problem.
D. AvailabilityF We have to switch off our mobiles in aeroplanes. &t is not advisable to use mobiles at places like
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petrochemical plants and petrol pumps. Availability of radiowaves causes another concern.
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G. BecurityF • • •
@adiowaves penetrate through walls. (hey can be intercepted. &f someone has knowledge and bad intentions then he may misuse it.
9. Alternative to @adiowaves in $lectromagnetic BpectrumF •
Bo there are four ma=or concerns i.e., capacity,efficiency,availability,security related with @adiowaves.
•
ut on the other hand we have G* billions of light box already installed and light is part of electromagnetic
•
•
spectrum. Bo let’slook up at this in context of $0 spectrum.
'amma rays are simply very dangerous and thus can’t be used for our purpose of
•
communication. U+rays are good in hospital and can’t be used either. 1ltra+violet raysare sometimes good for our skin but for long duration it is dangerous. &nfra+red rays are bad for our eyes and are therefore used at low power levels. We have already seen shortcomings of radiowaves.
•
Bo we are left with only -isible light spectrum.
• • •
LI-FI 'AS A #00&R'A" "#& T! 0ARALL&L "ATA TRAS/ISSI!
Conclusion6
(he possibilities are numerous and can be explored further. &f his technology can be put into practical use, every bulb can be used something like a Wi+i hotspot to transmit wireless data and we will proceed toward the cleaner, greener, safer and brighter future. (he concept of #i+i 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. (his may solve issues such as the shortage of radio+fre?uency 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.
R&F&R&C&S Q)R seminarpro=ects.comIsIseminar+report+on+lifi Q4R httpFIIen.wikipedia.orgIwikiI#i+i QDR httpFIIteleinfobd.blogspot.inI4*)4I*)Iwhat+is+lifi.html QGR technopits.blogspot.comtechnology.cgap.orgI4*)4I*)I))Ia+lifi+worldI Q9R www.lificonsortium.orgI
QJR the+gadgeteer.comI4*))I*8I4NIli+fi+internet+at+thespeed+of+lightI Q:R en.wikipedia.orgIwikiI#i+i Q8R Will #i+i be the new Wi+i, 7ew Bcientist, by 3amie ondliffe, dated 48 3uly 4*)) QNR httpFIIwww.digplanet.comIwikiI#i+i Q)*R !-isible+light communicationF (ripping the light fantasticF A fast and cheap optical version of Wi+i is coming!, $conomist, dated 483an 4*)4.
