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Li-Fi (Light Fidelity) The future technology In Wireless communication INTRODUCTION LiFi 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 the optical version of Wi-Fi. The term was first used in thiscontext by Harald Haas in his TED Global talk on Visible Light Communication. At the heart of this 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 its 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 Edingburgh are focusing on parallel data transmission using array of LEDs, where each LED transmits a different data stream. Other group 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 metres.
Light is inherently safe and can be used in places where radio frequency communication is often deemed problematic, such as in aircraft cabins or hospitals. So visible light communication not only has the potential to solve the problem of lack of spectrum space, but can also enable novel application. The visible light spectrum is unused; it's not regulated, and can be used for communication at very high speeds. Fig.1 Li-Fi environment 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.
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 its 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 aresome LEDs and a controller that code data into those LEDs. We have to just vary the rate atwhich the LEDs 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 lights frequency with each frequencyencoding 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 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 its potential to compete with conventional Wi-Fi has inspired the popular characterization Li-Fi. 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 and 2) a silicon photodiode which shows good response to visible wavelength region serving as the receiving element? LED can be switched on and off to generate digital strings of 1s and 0s. Data can be encoded in the light to generate a new data stream by varying the flickering rate of the LED. To be clearer, by modulating the LED light with the data signal, the LED illumination can be used as a communication source. As the flickering rate is so fast, the LED output appears constant to the human eye. A data rate of greater than 100 Mbps is possible by using high speed LEDs with appropriate multiplexing techniques. VLC. data rate can be increased by parallel data transmission using LED arrays where each LED 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.
INTERNET POWER I AMPLIFICATION AND PROCESSING 0 PHOTO-DETECTOR HOW IT WORKS An overhead lamp fitted with an LED with signal-processing technology (below) streams data embedded in its beam at ultra-high speeds to the photo-detector. A receiver dongle then converts the tiny changes in amplitude into an electrical signal, which is Fig 2.Data transmission using LED
COMPARISION 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. APPLICATION 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, I dont know, delegate red light to priority medical data. Code Red! Airlines: Airline Wi-Fi. Ugh. Nothing says captive audience like having to pay for the "service" of dial-up speed Wi-Fi on the plane. And dont get me started on the pricing. The best Ive 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, I have twice that capacity in my living room. And at the same price as checking a bag, I expect it. Li-Fi could easily introduce that sort of speed to each seat's reading light. Ill be the guy wowing next to you. Its better than listening to you tell me about your wildly successful son, maam.
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 plants own reserves could be lessened if they havent yet converted to LED lighting. 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 isnt 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. PRESENT SCENARIO: We have 1.4 million cellular radio waves base stations deployed. We also have over 5 billions of mobile phones. Mobile phone transmits more than 600TBb of data. Wireless communication has become a utility like electricity & water. We use it in everyday life, in our private life, business life. Currently wifi uses Radio waves for communication. It is important to look into this technology which has become fundamental to our
life.
Four Issues with Radio Waves: 1. Capacity: We transmit wireless data through radio waves. Radio waves are limited, scar and expensive. We only have a certain range of it. With the advent of the new generation technologies as of likes of 2.5G, 3G, 4G and so on we are running out of spectrum. 2. Efficiency: There are 1.4 million cellular radio base stations. They consume massive amount of energy. Most of this energy is not used for transmission but for cooling down the base stations. Efficiency of such a base station is only 5% and that raise a very big problem. 3. Availability: We have to switch off our mobiles in aeroplanes. It is not advisable to use mobiles at places like petrochemical plants and petrol pumps. Availability of radio waves causes another concern. 4. Security: Radio waves penetrate through walls. They can be intercepted. If someone has knowledge and bad intentions then he may misuse it.
5. Alternative to Radio waves in Electromagnetic Spectrum: So there are four major concerns i.e., capacity, efficiency, availability, security related with Radio waves. But on the other hand we have 40 billions of light box already installed and light is part of electromagnetic spectrum. So lets look up at this in context of EM spectrum. Electromagnetic Spectrum Radio Infra .. . Ultra- Gamma waves red visible violet x-rays ravs ----------------------------------------------------1 Frequency x 10 000 Gamma rays are simply very dangerous and thus cant be used for our purpose of communication. X-rays are good in hospital and cant be used either. Ultra-violet rays are sometimes good for our skin but for long duration it is dangerous. Infra-red rays are bad for our eyes and are therefore used at low power levels. We have already seen shortcomings of radio waves. So we are left with only Visible light spectrum.
393256176393256176393256176393256176-lifi.docx

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393256176393256176393256176393256176-lifi.docx

  • 1. Li-Fi (Light Fidelity) The future technology In Wireless communication INTRODUCTION LiFi 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 the optical version of Wi-Fi. The term was first used in thiscontext by Harald Haas in his TED Global talk on Visible Light Communication. At the heart of this 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 its 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 Edingburgh are focusing on parallel data transmission using array of LEDs, where each LED transmits a different data stream. Other group 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 metres.
  • 2. Light is inherently safe and can be used in places where radio frequency communication is often deemed problematic, such as in aircraft cabins or hospitals. So visible light communication not only has the potential to solve the problem of lack of spectrum space, but can also enable novel application. The visible light spectrum is unused; it's not regulated, and can be used for communication at very high speeds. Fig.1 Li-Fi environment 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.
  • 3. 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 its 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 aresome LEDs and a controller that code data into those LEDs. We have to just vary the rate atwhich the LEDs 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 lights frequency with each frequencyencoding 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
  • 4. eye can detect, causing the light source to appear to be on continuously, even though it is in fact 'flickering'. This invisible on-off activity enables a kind of data transmission using binary codes: switching on an LED is a logical '1', switching it off is a logical '0'. Information can therefore be encoded in the light by varying the rate at which the LEDs flicker on and off to give different strings of 1s and 0s. This method of using rapid pulses of light to transmit information wirelessly is technically referred to as Visible Light Communication (VLC), though its potential to compete with conventional Wi-Fi has inspired the popular characterization Li-Fi. 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 and 2) a silicon photodiode which shows good response to visible wavelength region serving as the receiving element? LED can be switched on and off to generate digital strings of 1s and 0s. Data can be encoded in the light to generate a new data stream by varying the flickering rate of the LED. To be clearer, by modulating the LED light with the data signal, the LED illumination can be used as a communication source. As the flickering rate is so fast, the LED output appears constant to the human eye. A data rate of greater than 100 Mbps is possible by using high speed LEDs with appropriate multiplexing techniques. VLC. data rate can be increased by parallel data transmission using LED arrays where each LED 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.
  • 5. INTERNET POWER I AMPLIFICATION AND PROCESSING 0 PHOTO-DETECTOR HOW IT WORKS An overhead lamp fitted with an LED with signal-processing technology (below) streams data embedded in its beam at ultra-high speeds to the photo-detector. A receiver dongle then converts the tiny changes in amplitude into an electrical signal, which is Fig 2.Data transmission using LED
  • 6. COMPARISION 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. APPLICATION 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, I dont know, delegate red light to priority medical data. Code Red! Airlines: Airline Wi-Fi. Ugh. Nothing says captive audience like having to pay for the "service" of dial-up speed Wi-Fi on the plane. And dont get me started on the pricing. The best Ive 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, I have twice that capacity in my living room. And at the same price as checking a bag, I expect it. Li-Fi could easily introduce that sort of speed to each seat's reading light. Ill be the guy wowing next to you. Its better than listening to you tell me about your wildly successful son, maam.
  • 7. 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 plants own reserves could be lessened if they havent yet converted to LED lighting. 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 isnt 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. PRESENT SCENARIO: We have 1.4 million cellular radio waves base stations deployed. We also have over 5 billions of mobile phones. Mobile phone transmits more than 600TBb of data. Wireless communication has become a utility like electricity & water. We use it in everyday life, in our private life, business life. Currently wifi uses Radio waves for communication. It is important to look into this technology which has become fundamental to our
  • 9. Four Issues with Radio Waves: 1. Capacity: We transmit wireless data through radio waves. Radio waves are limited, scar and expensive. We only have a certain range of it. With the advent of the new generation technologies as of likes of 2.5G, 3G, 4G and so on we are running out of spectrum. 2. Efficiency: There are 1.4 million cellular radio base stations. They consume massive amount of energy. Most of this energy is not used for transmission but for cooling down the base stations. Efficiency of such a base station is only 5% and that raise a very big problem. 3. Availability: We have to switch off our mobiles in aeroplanes. It is not advisable to use mobiles at places like petrochemical plants and petrol pumps. Availability of radio waves causes another concern. 4. Security: Radio waves penetrate through walls. They can be intercepted. If someone has knowledge and bad intentions then he may misuse it.
  • 10. 5. Alternative to Radio waves in Electromagnetic Spectrum: So there are four major concerns i.e., capacity, efficiency, availability, security related with Radio waves. But on the other hand we have 40 billions of light box already installed and light is part of electromagnetic spectrum. So lets look up at this in context of EM spectrum. Electromagnetic Spectrum Radio Infra .. . Ultra- Gamma waves red visible violet x-rays ravs ----------------------------------------------------1 Frequency x 10 000 Gamma rays are simply very dangerous and thus cant be used for our purpose of communication. X-rays are good in hospital and cant be used either. Ultra-violet rays are sometimes good for our skin but for long duration it is dangerous. Infra-red rays are bad for our eyes and are therefore used at low power levels. We have already seen shortcomings of radio waves. So we are left with only Visible light spectrum.