Li-Fi Technology
ACKNOWLEDGEMENT
I wish to extend my sincere gratitude to my seminar guide, Mr. Padmesh Singh Senior Lecturer, Department of Electrical Engineering, for his valuable guidance and encouragement which has been absolutely helpful in successful completion of this seminar. I am indebted to Mr. Pradeep Kumar Verma Assistant Professor, Department of Electrical Engineering and Mr. Pankaj Shukla Lecturer, Department of Electrical Engineerig for their valuable support. I am also grateful to my parents and friends for their timely aid without which I wouldn’t have finished my seminar successfully. I extend my thanks to all my well-wishers and all those who have contributed directly and indirectly for the completion of this work. And last but not the least; I thank God Almighty for his blessings without which the completion of this seminar would not have been Possible
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Li-Fi Technology
ABSTRACT
With the vast growing gadgets, their usage and their developments led to the advancement in the Wi-Fi which provides a technology so called Li-Fi.Li-Fi is a 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 WiFi.Light reaches nearly everywhere so communication can also go along with light freely. 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.. Dr herald Haas ,the professor of mobile communications at the university of Edinburgh school of engineering ,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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INDEX Acknowledgement
01
Abstract
02
Index
03
1. Introduction
06
1.1 What is Li-Fi? 2. History of Li-Fi
07
3. Principle of Li-Fi
08
4. Genesis of Li-Fi
08
5. How Li-Fi works?
09
5.1 Environmental condition 5.2 Visible light communication 6. Technical presentation of VLC light fidelity
13
7. Why Li-Fi?
14
7.1 Present scenario in Wireless Communication 7.2 Issues with Wi-Fi using Radio Waves 7.3 Alternatives to Radio Waves in spectrum 8. What we have to do?
16
9. Is it a proven technology?
16
10. How Li-Fi overcomes issues attached with w ith Radio Waves
16
10.1 Capacity BBDNIIT
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10.2 Efficiency 10.3 Safety 10.4 Security 11. Potential application of Li-Fi
17
12. Will Li-Fi be new Wi-Fi?
19
13. Advantages/Disadvantages of Li-Fi
21
13.1 Advantages 13.2 Disadvantages 14. Future
22
14.1 Reduction in Accident Numbers 14.2 Replacement for others Technologies 15. Related researches
24
15.1 Experimental study on VLC based on LED 16. Limitations of Li-Fi
25
17. Five reasons to promote Li-Fi Technologies
26
17.1 Distance 17.2 Cost 17.3 Traffic Updates 17.4 Game consoles 17.5 Television Interaction 18. Comparison between Li-Fi and Wi-Fi
27
18.1 Congestion BBDNIIT
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18.2 Safety 18.3 Security 18.4 Speed 19. Common myths of Li-Fi
30
20. Challenges for Li-Fi
30
21. Photo Gallery
31
22. Conclusion
32
23. Bibliography
33
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1. INTRODUCTION 1.1 What is LI-FI? Li-Fi is a VLC, visible light communication, technology developed by a team of scientists including Dr Gordon Povey, Prof. Harald Haas and Dr MostafaAfgani at the University of Edinburgh. The term Li-Fi was coined by Prof. Haas when he amazed people by streaming high-definition video from a standard LED lamp, at TED Global in July 2011. Li-Fi is 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 now part of the Visible Light Communications (VLC) PAN IEEE 802.15.7 standard. “Li -Fi is typically implemented using white LED light bulbs. These devices are normally used for illumination by applying a constant current through the LED. However, by fast and subtle variations of the current, the optical output can be made to vary at extremely high speeds. Unseen by the human eye, this variation is used to carry high-speed data, “says Dr Povey, , Product Manager of the University of Edinburgh's Li-Fi Program „D-Light Project”. 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.
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2. THE HISTORY OF LI-FI Alexander Graham Bell is most famous for inventing the telephone, but he also demonstrated the first VLC system in 1880. In fact only 4 years after inventing the telephone, Bell demonstrated the world’s first wireless telephone call. He did this with an apparatus called a Photo phone that used light, not radio. Bell had to use daylight for transmission, which severely limited its practical use. Professor Harald Haas and his research team first developed the modern concept of Li-Fi at the University of Edinburgh, ironically in labs within the Alexander Graham Bell Building (Bell was born in Edinburgh and attended the University). Li-Fi was developed as a solution to the growing radio spectrum congestion problems. Haas demonstrated the technology by streaming live video for the first time at TED Global in July 2011, and the term ‘Li-Fi’ was coined by him during this talk. The company pure VLC (www.purevlc.com) was created in 2012, in order to commercialize Li-Fi. Haraald 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 wireless spectrum available. The consortium believes it is possible to achieve more than 10Gbpsspeed using this optical wireless technology also known as Li-Fi. The communication is done by deploying transmit-ter and receiver in direct line of sight manner. It gets affected if line of sight is not used, the speed of data transmission will reduce or data transmission will stop. It is also more secure than other wireless net-works as only photo receptors are used, which can receive data within transmitted cone of light signals.
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3. PRINCIPLES OF LI-FI The basic idea behind this communication scheme is transmission of ‘Data through illumination’. The intensity of the LEDs is varied by changing the current passed through them at very high speeds. However, the human eye cannot perceive this change and the LEDs appear to have a constant intensity. This ON OFF activity of LED lights enables data transmission using binary codes i.e., when the LED is ON, logical ‘1’ is transmitted and when the LED is OFF, logical ‘0’ is transmitted. [2]This method of using rapid pulses of light to transmit data is called Visible Light Communication (VLC).
4. GENESIS OF LI-FI DR. Harald Hass, at TED
Talks
July
2011Harald
Haas,
professor
at
a 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 12th July 2011. He used a table lamp with an LED bulb to transmit a video of blooming flowers that was then projected onto a screen behind him. During the event he periodically blocked the light from lamp
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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.
5. HOW LI-FI WORKS? In order to know the working of Li-fi we need to know the necessity for Li-fi .With the vast development in living the use of gadgets and invention of new gadgets is increasing which lead to the technological developments There are many situations in which people get frustrated with the dull performance signals of Wi-Fi at a place with many network connections in seminars conferences etc. Li fi fulfills these needs .this fantabulous idea first striked the mind of Harald Haas from University of Edinburgh, UK, in his TED Global talk on VLC.His idea was very simple that if the
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LED is “on” then the digital 1 can be transmitted and if the led is “off” then the digital 0 can be transmitted.Led’s can be switched on and off very quick.For transmitting data this way all that we require is LED’s and controller that code data into LED’s.Parallel data transmission can be done by using array of LED’s or by using red, green, blue LED’s to alter light frequency with the frequency of different data channel. Ad-vancements and enhancements in this field generate a speed of 10 gbps! But amazingly fast data rates and lowering band widths are not the only reasons that enhance this technology.Lifi usually is based on light and so it can be probably implemented in articrafts and hospitals that are prone to inference from radio waves.unlike Wi-Fi Li-Fi can work even under-water which makes it more advantageous for military operations. Radio waves are replaced by light waves in data transmission call
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Light emitting diodes can be switched on and off very much faster than the human eye allowing the light source to appear continuously. The data transmission is done through binary codes which involve switching on LED can be done by logic 1 and switch off using logic 0.The encoding of information in light can therefore be identified by varying the rate at which the LED’s flicker on and off to give strings of 0’s and 1’s.visible
5.1 Environmental Condition The lamp performance is stated for the following environmental conditions:
At ambient temperatures higher than 45 C, the driver temperature can exceed its recommended limits which will impact its long term reliability. In order to
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operate for long periods of time at elevated ambient temperatures, the LiFi driver must be heat sunk more thoroughly and its base temperature validated at the elevated temperatures. The RF cable is also rated for up to 105º C temperature surrounding and therefore should not exceed this limit if operating in higher ambient temperatures.
At ambient temperatures lower than -40 C, start time becomes longer and can exceed the specification for the system. Though there is no specific impact on lifetime or reliability at cold temperatures, the lamp may experience difficulty in igniting or warming up to full brightness in the allotted time.
5.2 Visible Light Communication 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. Fast pulses are used for wireless transmission. Communication system components are: 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 tech-niques.Each LED transmits at a different data rate which can be in-creased 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
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6. TECHNICAL PRESENTATION OF THE VISIBLE LIGHT COMMUNICATION LIGHT FIDELITY Diagram mentioned below shows the topological representation how the LI-FI will work in the offices and work place. Diagram shows that how the visual light communication communicates to connect the different devices and media and also shows the probable path of the communication and of course transmitting the data and audio-video signals. In addition to how the peripheral devices may be utilized optimally. BBDNIIT
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7. WHY LI-FI? 7.1 Present Scenario In Wireless Communication
There are 1.4million cellular radio masts deployed worldwide.
There are more than five billion Wi-Fi devices present.
With all these devices, we transmit more than 600 terabytes of data every month.
Wireless communications has become a utility like electricity and water. We use it every day. We use it in our everyday lives now -- in our private lives, in our BBDNIIT
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business lives. And we even have to be asked sometimes, very kindly, to switch off the mobile phone at events like this for good reasons. And , therefore , it is very important to look into the issues that this technology has, because it's so fundamental to our lives.
7.2 Issues With Wi-Fi Using Radio Waves- There are four issues with the current Wi-Fi scenario, which are:7.2.1 Capacity- o
We transmit wireless data is by using electromagnetic waves -- in particular, radio waves.
o
Radio waves are scarce, expensive and we only have a certain range of it.
o
Due to this limitation one can’t forever hope to cope with the demand of wireless data transmissions and the number of bytes and data which are transmitted every month.
o
With the advent of the new generation technologies like 2g , 3g , 4g and so on we are running out of spectrum.
7.2.2 Efficiency- o
There are 1.4million cellular radio masts deployed worldwide.
o
Most of the energy consumed, is not used to transmit the radio waves, but is used to cool the base stations.
o
The efficiency of such a base station is only at about five percent.
7.2.3 Health Issues- o
There are potential health issues associated with radio waves.-phones in places like hospitals.
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o
Consequently we have to switch off devices like cell-phones in places like hospitals.
7.2.4 Security- o
The radio waves penetrate through walls.
o
They can be intercepted, and somebody can make use of one’s network.
7.3 Alternatives To Radio Waves In SpectrumThe issues concerning radio waves beg a close inspection at EM Spectrum for some alternative. The EM Spectrum is as given below:
Gamma rays can’t be used as they could be dangerous.
X-Rays have similar health issues.
Ultraviolet Light is good for a nice suntan, but otherwise dangerous for the human body.
Infrared, due to eye safety regulations, can only be used with low power.
Hence we are left with only the Visible Light Spectrum.
.
8. WHAT WE HAVE TO DO?
We have to replace inefficient fluorescents lights with this new dignitaries of LED lights.
It is a semi conductive e-device.
The LED bulb will hold a micro chip that will do the job of processing the data.
Light intensity can be modulated at very high speeds to send data by tiny changes in amplitude.
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9. IS IT A PROVEN TECHNOLOGY?
Yes this is already proven!
Harald Haas demonstrated his invention using an ordinary table lamp that successfully transmitted data at speeds exceeding 10mbps using light waves from LED light bulbs to a computer located below the lamp.
To prove that the light bulb was the source of the data stream he periodically blocked the beam of light , causing the connection to drop!
10. HOW LI-FI OVERCOMES ISSUES ATTACHED WITH RADIO WAVES:-
10.1 Capacity
We have 10,000 times more spectrum in visible light region than in the radio waves region.
Therefore we have 10,000 times more channels to transmit data.
10.2 Efficiency
Led consumes very little power therefore the data transmission is very efficient.
10.3 Safety
Visible light poses no health issue.
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10.4 Security
Light waves don’t penetrate through walls.
Therefore they can’t be intercepted easily.
11. POTENTIAL APPLICATIONS OF LI-FI Li-Fi technology is still in its infancy. However some areas where it seems perfectly applicable are:
Smart Lighting. Any private or public lighting including street lamps can be used to provide Li- Fi
Hotspots and the same communications and sensor infrastructure can be used to monitor and control lighting and data.
Indoor Positioning. Transmission of a unique ID is all that is required for basic positioning. Multiple LED light bulbs can be used with tri late ration for more accurate indoor positioning and navigation.
Mobile Connectivity. Laptops, smart phones, tablets and other mobile devices can interconnect directly using VLC. Short range links give very high data rates and also provides security via the visible pairing method.
Hazardous Environments. VLC provides a safe alternative to electromagnetic interference from RF communications in environments such as mines and petrochemical plants.
Vehicles &
Transportation.
LED headlights
and tail-lights are being
introduced. Street lamps, signage and traffic signals are also moving to LED. This
can
be
used
for vehicle-to-vehicle
and
vehicle-to-roadside
communications. This can be applied for road safety and traffic management.
Hospital & Healthcare. VLC emits no electromagnetic interference and so does not interfere with medical instruments, nor is it interfered with by MRI scanners.
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Wi-Fi Spectrum Relief. Excess capacity demands of Wi-Fi networks can be off-loaded to VLC networks where available. This is especially effective on the downlink where bottlenecks tend to occur. o
Aviation . LEDs are being used in aircraft passenger cabins. VLC can be
used to reduce weight and cabling and adding flexibility to seating layouts. The in-flight entertainment systems can be supported by VLC. o
Underwater Communications. Due to strong signal absorption in water,
RF use is impractical. Acoustic waves have extremely low bandwidth and disturb marine life. VLC provides a solution for short-range communications. o
RF
Avoidance. Some people claim they are hypersensitive to
radiofrequencies and are looking for an alternative. VLC is a good solution to this problem. o
Toys. Many toys incorporate LED lights and these can be used to enable
extremely low-cost communication between interactive toys.
12. WILL LI-FI BE THE NEW WI-FI?
FLICKERING lights are annoying but they may have an upside. Visible light communication (VLC) uses rapid pulses of light to transmit information wirelessly. Now it may be ready to compete with conventional Wi-Fi. BBDNIIT
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"At the heart of this technology is a new generation of high-brightness lightemitting 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 transmitting 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 eyes cannot notice, so the output appears constant. More sophisticated techniques could dramatically increase VLC data rates. Teams at the University of Oxford and the University of Edinburgh are focusing on parallel data transmission using arrays of LEDs, where each LED transmits a different data stream. Other groups are using mixtures of red, green and blue LEDs to alter the light's frequency, with each frequency encoding a different data channel. Li-Fi, as it has been dubbed, has already achieved blisteringly high speeds in the lab. Researchers at the Heinrich Hertz Institute in Berlin, Germany, have reached data rates of over 500 megabytes per second using a standard white-light LED. Haas has set up a spin-off firm to sell a consumer VLC transmitter that is due for launch next year. It is capable of transmitting data at 100 MB/s - faster than most UK broadband connections. Once established, VLC could solve some major communication problems. In 2009, the US Federal Communications Commission warned of a looming spectrum crisis: because our mobile devices are so data-hungry we will soon runout of radio-frequency bandwidth. Li-Fi could free up bandwidth, especially as much of the infrastructure is already in place
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"There are around 14 billion light bulbs worldwide, they just need to be replaced with LED ones that transmit data," says Haas. "We reckon VLC is a factor of ten cheaper than Wi-Fi." Because it uses light rather than radio-frequency signals, VLC could be used safely in aircraft, integrated into medical devices and hospitals where Wi-Fi is banned, or even underwater, where Wi-Fi doesn't work at all. "The time is right for VLC, I strongly believe that," says Haas, who presented his work at TED Global in Edinburgh last week. But some sound a cautious note about VLC's prospects. It only works in direct line of sight, for example, although this also makes it harder to intercept than WiFi. "There has been a lot of early hype, and there are some very good applications," says Mark Leeson from the University of Warwick, UK. "But I'm doubtful it's a panacea. This isn't technology without a point, but I don't think it sweeps all before it, either.
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13. ADVANTAGES/DISADVATAGES OF LI-FI
13.1 Advantages-
Superiority Over RF Waves-
As was demonstrated earlier, the visible light has considerable edge over RF waves in many fields.
Little Infrastructure Requirements-
There are an estimated 14 billion bulbs in the world today. Since Li-Fi can operate on conventional LEDs infrastructure is pretty much present already.
Simple System Structure-
A typical Li-Fi system consists of an LED array, a photo receiver, a de/modulator pair. Li-Fi can solve problems related to the insufficiency of radio frequency bandwidth because this technology uses Visible light spectrum that has still not been greatly utilized. High data transmission rates of up to 10Gbps can be achieved. Since light cannot penetrate walls, it provides privacy and security that Wi-Fi cannot. Li Fi has low implementation and maintenance costs. It is safe for humans since light, unlike radio frequencies, cannot penetrate human body. Hence, concerns of cell mutation are mitigated.
13.2 DisadvantagesThe biggest disadvantage is that it needs direct line of sight to transmit data, so one wouldn't be able to have a single router in his/her house and the data goes through walls etc.
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14. FUTURE In 2009, the US Federal Communications Commission warned of a looming spectrum crisis: because our mobile devices are so data-hungry we will soon run out of radio-frequency bandwidth. Li-Fi could free up bandwidth, especially as much of the infrastructure is already in place. The solution might be Li-Fi. Direct modulation of LED devices is a low cost, secure, and safe way to transmit data, and there is an abundance of free visible light spectrum. High intensity LEDs used in light bulbs, flash lights and cameras can transmit very high data rates, faster than Wi-Fi. And the technique looks good not only on paper. At Heinrich Hertz Institute in Berlin, Germany researchers have achieved a data rate of 500 megabytes per second using a standard white LED. This year’s, 2012, Consumers Electronics Show in Las Vegas demonstrated VLC in full vigor when a pair of Casio smart phones exchanged data using light of varying intensity given off from their screens. In October, 2011 a number of companies and industry groups formed the Li-Fi Consortium to work towards and promote Light Fidelity (Li-Fi) in order to overcome the rapidly diminishing bandwidth for Wireless Fidelity (Wi-Fi).However everyone is not so optimistic. Dr Suresh Borkar, a trend-watcher, consultant and communications expert, who teaches at the Illinois Institute of Technology, opines that at the current stage of maturity, LiFi usage will be limited to in-house and proximity applications. The use of very high frequency (400-800 THz) limits it to very short distances and more of pointto-point communications. Li-Fi, according to Dr Borkar, is still in the experimental laboratory stage. Standards have to be defined and devices identified and made available along with the infrastructure and related entities before it can be used widely. Some limited proto type friendly deployments have taken place in the last year or so but the availability of receiving devices that require arrays of photodiodes is still limited.
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14.1 Reduction In Accident Numbers- 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.
14.2 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 color fidelity.
Instant start time.
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 ad-vantageous 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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15. RELATED RESEACHES
15.1 Experimental Study on Visible Light Communication Based on LEDWANG Jia-Yuan, ZOU Nian-Yu, WANG Dong, IRIE Kentaro, IHA Zensei, NAMIHIRA Yoshinori The Journal of China Universities of Posts and Telecommunications In this paper, the illumination of the receiving surface for different distances between the LED and photodiode receiver was tested. It was found that with the increase in communication distance, the illumination sharply reduced. When the distance is greater than 85cm, the surface illumination of photodiode is less than 100 lx and when the distance is greater than 120cm, the surface illumination of photodiode is very weak i.e., close to 0 lx. The variation of bit error rate (BER) v/s communication distance was also tested and it was found that the system can provide a bit rate of up to 111.607Kbps at distances within 1.5m, and when the distance is high, the BER is very high and limits the bit rate.
15.2 VISIBLE LIGHT COMMUNICATION: Recent Progress and ChallengesDominic O’Brien, Hoa Le Minha, Lubin Zeng, Grahame Faulkner and His Hsir Chou, Kyungwoo Lee, Daekwang Jung, YunJe Oh, Eun Tae Won Wireless World Research Forum .In this White Paper from the Wireless World Research Forum (WWRF), it was proved that performance of receiver need not be considered for bandwidths up to 100MHz. To increase data rates, performance of LEDs must be enhanced. It also identified the most challenging problem for VLC as the compatibility with PWM dimming systems. They proposed approaches that combine modulation with dimming.
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16. LIMITATIONS OF LI-FI
Only works if there is direct line of sight (LOS) between the transmitter and receiver.
Data transmission can be easily obstructed by opaque obstacles.
The use of very high frequencies (400-800THz) limits it to vey short distances and point to point communications only.
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. Interferences 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.
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17. FIVE REASONS TO PROMOTE Li-Fi TECHNOLOGIES Although the use of light in order to transmit data can be limited in comparison to radio waves, there is a great amount of possibilities that can be developed due to this technology. In essence, a single pixel of a monitor could transmit a single channel of information to a source. Although this technology is still in its infant stages, the usefulness of this Li-Fi technology has implications for a great amount of good.
17.1 Distance- The sheer range of transmitting information could be worth the decrease in data speeds. The RONJA project in the Czech Republic can transmit a 10 Mbit/s Ethernet-type link just under a mile. As developments of this aspect continue, the range could be entirely up to the strength of the light which is emitting the information. Although the speeds are less than what they are for gigabit Ethernet, the power of the beam can allow DVD-quality streaming of video to any location connected to the Li-Fi device.
17.2 Cost- Instead of running close to a mile worth of cable, the LED-powered Li-Fi connection could be used to beam the information directly to the destination. Using a point-to-point array, office buildings can stay connected to each other without the use of additional cables being laid from one access point to another. The only problem the two buildings would be faced with is obstruction by solid objects or dense weather patterns such as heavy fog or snow.
17.3 Traffic Updates- Could you imagine having a car that uses a GPS system that receives information from traffic lights informing you of accidents and/or delays up ahead? There is a kind of system like that already in play for GPS navigational systems, but the traffic lights could be updating drivers using basic information or streaming video directly from news broadcasts.
17.4 Game Consoles- An innovative idea would be to put sensors on a television in order to receive information from game consoles. This would allow the unit to be place literally anywhere within the room as long as there is a direct line of sight to the sensor. Could you imagine a game system like the Xbox using BBDNIIT
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a Kinect and all of it being completely wireless except for the power going into the unit? That will be tackled once wireless energy is perfected for practical home use.
17.5
Television
Interaction- Instead of using apps or additional
installations, you could theoretically hold your phone up as you sit on the couch and have every piece of information regarding the show or movie you are currently watching sent to your display – even recording directly to your mobile device. Of course, this may spawn some kind of copyright lawsuit because you are illegally copying a movie or television show, but you still get the idea. There are a number of reasons why investing in Li-Fi technology can have a great benefit to the future of wireless networking. Although there are a few aspects that need to be ironed out before it can be introduced on a wide scale of practicality, the future looks to be very promising. Even if the technology was merely developed as a small scale indoor application to “beam” information directly to a computer system without the use of Ethernet cable being strewn about the floor, visible-light communications could set the benchmark higher for wireless transmissions.
18. COMPARISON BETWEEN LI-FI AND WI-FI
Li-Fi is a terminology which is used to describe visible light communication technology applied to high speed wireless communication. 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. Li-Fi can turn an LED lamp into a wireless access point similar to a Wi-Fi router, so apart from the added advantage of illumination, how do they differ?
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18.1 Congestion- Wi-Fi uses radio frequencies, and these are very limited. Devices – computers, laptops, printers, smart TVs, smart phones and tablets – BBDNIIT
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must compete for bandwidth. The emergence of more and more Wi- Fi-enabled things e.g. refrigerators, watches, cameras, and offloading from cellular is
causing congestion, and degrading data communications. Li-Fi uses the frequencies of light waves, which are up to 10,000 times more plentiful than radio frequencies and do not compete with Wi-Fi.
18.2 Safety- Wi-Fi creates Electromagnetic Interference (EMI), known to interfere with airplanes’ instruments and equipment in hospitals, and is potentially dangerous in hazardous operations, such as power/nuclear generation or oil and gas drilling. Li-Fi uses light instead of radio waves, which is intrinsically safe and does not create EMI.
18.3 Security- Radio waves pass through walls and ceilings. Light doesn’t. Therein lies the difference in data security between Wi-Fi and Li-Fi. An intruder or hacker, outside a building can tap into the Wi-Fi data communications of computers inside the building. Data communicated via Li-Fi can only be accessed where the LED light illuminates.
18.4 Speed- Wi-Fi standard, 802.11a/g, provides data communication rates up to 54Mbps. However, there are techniques available to extend this to 1Gbps. The University of Edinburgh, pure VLC's partner and home to Prof. Harald Haas – “the father of Li-Fi” have already demonstrated 3Gbps on a single color. On a single LED with full color (R, G, B) this could communicate at speeds up to 9Gbp
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19. COMMON MYTHS OF LI-FI
Uni-Directional Only- No, Li-Fi can be implemented as a transceiver, providing both transmission and reception.
Visible Light Essential- No, Li-Fi enabled LEDs can be dimmed until no light is humanly visible, but data communications is still maintained reliably.
Line-Of-Sight Required - No , but desired. Li-Fi is perfectly capable of data communications from reflected light, but the signal will be stronger on direct light
Requires Special LEDs- No, Li-Fi does not requires any special LEDs for its implementation.
20. CHALLENGES FOR LI-FI
Apart from many advantages over Wi-Fi, Li-Fi technology is facing some challenges. Li-Fi requires line of sight. When set up outdoors, the apparatus would need to deal with ever changing conditions. Indoors, one would not be able to shift the receiving device. A major challenge facing Li-Fi is how the receiving device will transmit back to transmitter. One more disadvantage is that visible light can’t penetrate through brick walls as radio waves and is easily blocked by somebody simply walking in front of LED source [10]. A side effect of Li-Fi is that your power cord immediately becomes your data stream, so if you have power, you have internet.
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22. CONCLUSION
Li-Fi has great potential in the field of wireless data transmission. It is a promising alternative to conventional methods of wireless communications that use radio waves as data carrier. Many enhancements can be made to the existing technology. For example, encoding and decoding can be implemented directly in the transmitter and receiver part of the circuit. This would reduce error in transmission. Also, by using fast-switching LEDs, data transmission rates can be further enhanced. The driving speed of the circuit can be improved by using fastswitching transistors. The fact that Li-Fi is being considered as one of the IEEE 802.xx standards bodes well for its potential success. Like other 802.xx standards, it is defined only at layers 1 and 2 (physical and media access control (MAC) layers) of the Open Systems Interconnection (OSI) model. Layer 3 and higher layers need to Bede signed using the Internet Engineering Task Force (IETF) packet transport standards.Li-Fi is certainly not useless, but it has certain inherent limits for the technology. Li-Fi may not be able to replace conventional radios altogether, but it could turbo charge the development of wireless television and make it easier to throw a wireless signal across an entire house. At present, finding the ideal position for a wireless router is something of a divine art. If the signal could be passed via VLC from Point A to Point B inside a home, small local routers at both points could create local fields with less chance of overlapping and interfering with each other. 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 will 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 shortage of radio-frequency bandwidth and also allow internet where traditional radio based wireless isn’t allowed such as aircraft or hospitals. One of the shortcomings however is that it only work in direct line of sight. BBDNIIT
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