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  1. 1. SEMINAR ON TANSHU Page  1
  2. 2. Li-Fi can be thought of as a lightbased Wi-Fi. That is, it uses light instead of radio waves to transmit information. And instead of Wi-Fi modems, LiFi would use transceiver-fitted LED lamps that can light a room as well as transmit and receive information. Page  2
  3. 3. WHAT IS LI – FI ? • LI-FI is transmission of data through illumination ,ie sending data through a LED light bulb that varies in intensity faster than human eye can follow • LI FI- LIGHT FIDEALITY Page  3
  4. 4. HISTORY- The technology truly began during the 1990's in countries like Germany, Korea, and Japan where they discovered LED's could be retrofitted to send information. Harald Haas continues to wow the world with the potential to use light for communication HARALD HASS Page  4
  5. 5. 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 to prove that the lamp was indeed the source of incoming data. At TEDGlobal, Haas demonstrated a data rate of transmission of around 10Mbps -- comparable to a fairly good UK broadband connection. Two months later he achieved 123Mbps. Back in 2011 German scientists succeeded in creating an800Mbps (Megabits per second) capable wireless network by using nothing more than normal red, blue, green and yellw 0 Page  5
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  7. 7. PRESENT SCENARIO 5 Billion Radio Spectrum is congested but the demand for wireless data double each year .Every thing, it seems want to use wireless data but the capacity is drying up. 1.4 Million Page  7
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  11. 11. Radio Waves Infrared Rays Visible Rays Ultraviolet Rays X- Rays Gama Rays Gama rays cant be used as they could be dangerous. X-rays have similar health issues. Ultraviolet light is good for place without people, but other wise dangerous for the human body. Infrared, due to eye safety regulation, can only bse used with low power.  Page  11
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  14. 14. LED ie Light emitting diode can be switched on and off faster since operating speed of LED is less than 1 μs, than the human eye can detect, causing the light source to be appear continuously. This invisible onoff activity enables a kind of data transmission using binary codes. Switching on and LED is a logical ‘1’, switching it off is a logical ‘0’.It is possible to encode data in the light by varying the rate at which LED’s flicker on and off to give different strings of 1s and 0s. Modulation is so fast that human eye doesn’t notice Page  14
  15. 15. How LI-FI Works ? operational procedure is 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. Hence all that us required is some LEDS and a controller that code data into those LEDs. We have to just vary the rate at which the LED’s flicker depending upon the data we want to encode Thus every light source will works as a hub for data transmission Page  15
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  18. 18. Page  19 Further enhancements can be made in this method, like using an array of LEDs for parallel data transmission, or using mixtures of red, green and blue LEDs to alter the light‘s frequency with each frequency encoding a different data channel. Such advancements promise a theoretical speed of 10 Gbps – meaning one can download a full highdefinition film in just 30 seconds
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  20. 20. For giga-speed technologies, the Li-Fi Consortium defined GigaShower, GigaSpot and GigaMIMO models Page  21
  21. 21. GigaShower and Giga-MIMO are the other models for inhouse communication. There a transmitter or receiver is mounted into the ceiling connected to, for example, a media server GigaShower provides unidirectional data services via several channels to multiple users with gigabit-class com-munication speed over several metres. This is like watching TV channels or listening to different radio stations where no uplink channel is needed. In case GigaShower is used to sell books, music or movies, the connected media server can be accessed via Wi-Fi to process payment via a mobile device. GigaSpot and GigaMIMO are optical wireless single- and multi-channel HotSpot solutions offering bidirectional gigabitclass communication in a room, hall or shopping mall for example. Page  22
  22. 22. LI FI CONSTRUCTIONThe LI FI product consists of 4 primary sub-assemblies: • Bulb • RF power amplifier circuit (PA) • Printed circuit board (PCB) • Enclosure 3-The PCB controls the electrical inputs and outputs of the lamp and houses the microcontroller used to manage different lamp functions. 2- An RF (radio-frequency) signal is generated by the solid-state PA and is guided into an electric field about the bulb. The high concentration of energy in the electric field vaporizes the contents of the bulb to a plasma state at the bulb’s center; this controlled pasma generates an intense source of light. All of these subassemblies are contained in an aluminum enclosure. Page  23
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  26. 26. POTENTIAL APPLICATION OF LI-FI Li Fi technology is still in its infancy .However some areas where it seems perfectly applicable are:- 1- TRAFFIC LIGHTS  Traffic lights can communicate to the car and with each other. Cars have LED-based headlights, LED-based cack lights, and cars can communicate with each other and prevent accidents in by exchanging information. Page  27
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  28. 28. 2-INTRINSICALLY SAFE ENVIRONMENT Visible Light is more safe than RF, hence it can be used in places where RF can't be used such as petrochemical plants .  Page  29
  29. 29. 3- Airlines Whenever we travel through airways we face the problem in communication media ,because the whole airways communication are performed on the basis of radio waves. To overcomes this drawback on radioways , li-fi is introduced. Page  30
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  31. 31. 4- ON OCEAN BEDS Li-Fi can even wok underwater were Wi-Fi fails completely, thereby throwing open endless opportunities for military/navigation operations. Page  32
  32. 32.  PUBLIC INTERNET HOTSPOTS There are millions of street lamps deployed around the world. Each of these street lamps could be a free access point. Page  33
  33. 33. It will reduce your electricity bill and maintainance bill Page  34
  34. 34. Limitations 0r challenges# light can't pass through objects #. 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 #A major challenge facing Li-Fi is how the receiving device will transmit back to transmitter. Page  35
  35. 35. CONCLUSION 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 hotspots to transmit wireless data. Page  36
  36. 36. REFRENCES 1..http://www.electronicsforu.com/electronicsforu/ci rcuitarchives/view_article.asp?sno=778&title%20= %20LiFi%3A+A+New+Paradigm+in+Wireless+Communi cation&b_type=new&id=12042 2. http://en.wikipedia.org/wiki/Li-Fi 3. International Journal of advances in computing & communications, vol 1, 2013,page no-12 www.ijacc.org Page  37
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