1. 1. LI-FI TECHNOLOGY BY MANISH JAISWAL B110950EE
2. 2. CONTENTS : Introduction Why LI-FI ?? Difference Between The Technologies Components Block diagram Working process Applications Advantages Limitation Conclusion References
3. 3. INTRODUCTION TO What is exactly ?
4. 4. Introduction A German physicist, Dr. Harald Haas, has come up with a solution to address the problems with WIFI networks, he calls Data Through Illumination In simple terms, Li-Fi can be thought of as a light-based Wi-Fi. 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.
5. 5. 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. 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. LI-FI comes under VLC (VISIBLE LIGHT COMMUNICATION)
6. 6. If led is on , then we transmit a digital signal 1, and if the led is off , then we transmit a digital signal 0.
7. 7. Why VLC ??
8. 8. Why LI-FI ? Present Scenario: More than 1.8 Million More than 338 Million
9. 9. Drawbacks Of Before Technologies Issues Regarding Radio Spectrum:
10. 10. Cont o Capacity Radio waves Cost and expensive Less bandwidth compared to other spectrums Insufficient spectrum for increasing data o Efficiency Millions of base stations consume huge amount of energy for 1. Transmitting the radio waves 2. To cool the base station cabins 5 % efficiency
11. 11. Cont o Availability Availability within the range of base stations Limited availability Unavailability in aircrafts o Security Less secure(passes through the walls)
12. 12. Difference Between The Technologies
13. 13. Major Components of a LIFI Communication System Source A high brightness white LED, acts as a communication source Its guided by the PCB and powered by PA and is enclosed in an aluminum enclosure Bulb: The high concentration of energy in the electric field vaporizes the contents of the bulb to a plasma state at the bulbs center; this controlled plasma generates an intense source of light. RF power amplifier circuit (PA): An RF (radio-frequency) signal is generated by the solid-state PA(Power Amplifier) and is guided into an electric field about the bulb. Printed circuit board (PCB): The PCB controls the electrical inputs and outputs of the lamp and houses the microcontroller used to manage different lamp functions. Enclosure: All of these subassemblies are contained in an aluminum enclosure
14. 14. Cont Receiver A silicon photodiode, which shows good response to visible wavelength region serving as the receiving element.
15. 15. Block Diagram: RECEVING SIGNALS
16. 16. How LI-FI Works ?
17. 17. How LI FI Works
18. 18. How LI FI Works On one end all the data on the internet will be streamed to a lamp driver when the led is turned on the microchip converts the digital data in form of light. A light sensitive device (photo detector) receives the signal and converts it back into original data. This method of using rapid pulses of light to transmit information wirelessly is technically referred as Visible Light Communication
19. 19. Cont
20. 20. Function Of The Bulb: At the heart of LIFI is the bulb sub-assembly where a sealed bulb is embedded in a dielectric material. This design is more reliable than conventional light sources that insert degradable electrodes into the bulb. The dielectric material serves two purposes; first as a waveguide for the RF energy transmitted by the PA (power amplifier) and second as an electric field concentrator that focuses energy in the bulb. The energy from the electric field rapidly heats the material in the bulb to a plasma state that emits light of high intensity and full spectrum
21. 21. Working White LED light bulbs: Li-Fi is typically implemented using white LED light bulbs at the downlink transmitter which normally used for illumination only by applying a constant current. Optical output is varied at extremely high speed: The LEDs can be switched on and off very quickly which gives nice opportunity for data transfer in the form of Binary code. Hence, by fast and subtle variations of the current, the optical output can be made to vary at extremely high speeds. This very property of optical current is used in Li-Fi setup.
22. 22. Cont Operational Procedure: The operational procedure is very simple-, if the LED is on, you transmit a digital 1, if its off you transmit a 0.
23. 23. Cont Hence it is possible to encode the data into the LEDs by using a controller ,we just have to vary at which LEDs flicker depending on the data we want to encode to give different strings of 0s and 1s.
24. 24. Data transfer in binary code UK researches say that using a micro-LED light bulb they have achieved a data transmission speed of 10Gbps using LI-FI.
25. 25. 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 frequency encoding a different data channel. Such advancements promise a theoretical speed of 10 Gbps meaning one can download a full high-definition film in just 30 seconds
26. 26. Illustration
27. 27. OUTLOOK OF LI-FI Li-Fi communication with other Devices
28. 28. Properties of LIFI Light-based Wi-Fi: LIFI 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. Unutilized electromagnetic spectrum is used: This technology uses a part of the electromagnetic spectrum that is still not greatly utilized. The Visible Spectrum. No major ill effect: Light is in fact very much part of our lives for millions and millions of years and does not have any major ill effect.
29. 29. HOW THE BASIC LIGHT IS CONVERTED INTO ELECTRICITY Vacuum equations, electromagnetic waves and speed of light. Figure is a 3D diagram shows a plane linearly polarized wave propagating from left to right with the same wave equations from left to right. Where E = E0 sin(t + k r) and B = B0 sin(t + k r) In a region with no charges ( = 0) and no currents (J = 0), such as in a vacuum, Equation is reduced Maxwells equations.
30. 30. Cont Taking the curl () of the curl equations, and using the curl of the curl identity (X) = (X) 2X we obtain the wave equations. Which identify C is the speed of light in free space. In materials with relative permittivity r and relative permeability r, the phase velocity of light becomes which is usually less than c
31. 31. Potential Application Area: IN AIRCRAFT CABIN IN PETROCHEMICAL INDUSTRIES
32. 32. In Hospitals In Traffic
33. 33. Under Water In Home , Offices and Schools
34. 34. In Lecture Hall
35. 35. Advantages:
36. 36. Limitation or Challenges : Light can not pass through opaque objects. Interference from external source like sun light, normal bulbs opaque materials. High installation cost of VLC.
37. 37. The possibilities are numerous and can be explored further. If his technology can be put into practical use, every bulb can be used something like a Wi-Fi hotspot to transmit wireless data and we will proceed toward the cleaner, greener, safer and brighter future
38. 38. References: http://www.ted.com/talks/harald_haas_wireless_data_from_every_light _bulb.html www.ijacc.org http://oledcomm.com/lifi.html http://en.wikipedia.org/wiki/Li-Fi International Journal of advances in computing & communications, vol 1, 2013,page no-12