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Abstract: Li-Fi stands for Light-Fidelity,For the fast increasing gadgets and to improve more effective use of lights a new technology is developed which is called- LIFI. Lifi is a modern technology which is used in progression with WIFI technology. LIFI uses LED lights which helps in faster and flexible data transfer transmitted through Wi-Fi. As light is everywhere, using light as the transmission medium Li-Fi can provide wireless indoor communication. The data transfer through LIFI is in bits and is much faster than Wifi. Dr. herald Haas, the professor of mobile communications at the University of Edinburgh, UK, 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.
I. INTRODUCTION
The most important day-to-day activities in this fast world are the transfer of data and information. As the world is becoming faster the need of fast data transmission is also increasing. As the numbers of devices that access to the internet
are increasing, the limited bandwidth leads to decrease in the speed of the data transfer
To give a solution to this problem Li-Fi technology is introduced. Li-Fi stands for Light Fidelity. Li-Fi provides better bandwidth, efficiency, availability and security than Wi-Fi and thus increases the data transfer speed. Li-Fi technology provides transmission of data through illumination by taking the fibre out of fibre optics by sending data through an LED light bulb that varies in intensity faster than the human eye can follow. Li-Fi is ideal for high density wireless data coverage in confined area and for relieving radio interference issues.
Lifi uses visible light instead of Gigahertz radio waves for data transfer which makes it fast and cheap mode of wireless communication. The idea of Li-Fi was introduced by a German physicist, Harald Hass, which he also referred to as ―data through illumination‖. The term Li-Fi was first used by Haas in his TED Global talk on Visible Light Communication. According to Hass, the light, which he referred to as D-Light, can be used to produce data rates higher than 10 megabits per second which is much faster than our average broadband connection.
II. CONSTRUCTIONS OF LI-FI SYSTEM
The LIFI™ product consists of 4 primary sub-assemblies:
• Bulb
• RF power amplifier circuit (PA)
• Printed circuit board (PCB)
• Enclosure
The PCB controls the electrical inputs and outputs of the lamp and houses the microcontroller used to manage different lamp functions. 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 centre; this controlled plasma generates an intense source of light. All of these subassemblies are contained in an aluminium enclosure.
III. FUNCTIONS OF THE BULB SUB-ASSEMBLY
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 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
IV. WORKING OF LI-FI
A new era of large brightness light-emitting diodes forms the core part of lifi technology. The logic is so simple as follows-If the LED light is on, a digital 1 is transmitted. If the LED light is off, a digital 0 is transmitted. These large brightness LEDs lights can be switched on and off very quickly which gives us a very nice chance for transmitting data through light.
The working of Li-Fi is very easy as Wi-Fi . There is a light emitter on one corner, for example, an LED, and a photo detector (light sensor) on the other corner. The photo detector registers a binary one when the LED is on; and a binary
zero if the LED is off same as microprocessor. To generate any message, flash the LED numerous times or use an array of LEDs of perhaps a few different colours, to obtain data rates in the range of hundreds of megabits per second.
The data can be encoded in the light by varying the flickering rate at which the LEDs flicker on and off togenerate different strings of 1s and 0s.The LED intensity is modulated so rapidly that human eye cannot notice, so the light of the LED appears constant to humans 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, even though it is in fact 'flickering'.
The on-off activity of the bulb which seems to be invisible enables data transmission using binary codes: switching on an LED is a logical '1', switching it off is a logical '0'. By varying the rate at which the LEDs flicker on and off, information can be encoded in the light to differentcombinations 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 it is popularly called as Li-Fi because it can compete with its radio-based rival Wi- Fi.
The data can be encoded in the light by varying the flickering rate at which the LEDs flicker on and off togenerate different strings of 1s and 0s.The LED intensity is modulated so rapidly that human eye cannot notice, so the light of the LED appears constant to humans 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, even though it is in fact 'flickering'.
The on-off activity of the bulb which seems to be invisible enables data transmission using binary codes: switching on an LED is a logical '1', switching it off is a logical '0'. By varying the rate at which the LEDs flicker on and off, information can be encoded in the light to differentcombinations 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 it is popularly called as Li-Fi because it can compete with its radio-based rival Wi- Fi.