LIFI − Light Fidelity − Feel the Speed

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LIFI Light Fidelity Feel the Speed

Sonia Tomer1, Sonia Choudhary2 1,2Department of Computer Science &Engineering, Ganga Institute of Technology and Management,

Kablana, Jhajjar, Haryana, India

Abstract: Li-Fi Technology deals with large amount of speed of internet which is upto 10gbps. It is fast and cheap optical version of Wi-Fi. Li-Fi is a technology that uses the technology the light emitting diodes (LED) to transmit the data wirelessly

. The data rate of Li-Fi can be compared with size and numbers of LED bulb used in it. In Li-Fi data rate can be increased by increasing number of LEDs. In this we also discussed its literature review and its working phenomenon. What the need for the development of the technology and drawbacks of the technology which is overcome by this technology. This paper include the review of the brief description of Li-fi and its advantages and future scope .

Keywords Li-Fi , Wi-Fi, Emitter, RF Driver , Data rate


    Li-Fi means Light Fidelity. Li-Fi is fast and cheap optical version of Wi-Fi. Li-Fi is a technology that uses the technology the light emitting diodes (LED) to transmit the data wirelessly . The idea of Li-Fi was introduced by a German physicist, Harald Hass. The term Li-Fi was first used by Haas in his TED Global talk on Visible Light Communication. Li-fi based on visible light communication (VLC).VLC is a data communication medium ,Which uses the visible light between 400 Thz and 800 THz as optical carrier for data transmission. Li-Fi uses visible light communication in the range of 100Mbps.

    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. Li-Fi can be the technology for the future where data will be transmitted through the light in a room. In this paper, the comparison is made between Wi-Fi and Li-Fi technology.


    Professor Harald Haas, from the University of Edinburgh in the UK, is widely recognised as the original founder of Li-Fi. He is Chair man of Mobile Communications at the University of Edinburgh and co-founder of pure LiFi. The general term visible light communication (VLC), includes any use of the visible light portion of the electromagnetic spectrum to transmit information. The D-Light project at Edinburgh's Institute for Digital Communications was funded from January 2010 to January 2012. Mr. Haas promoted this technology in his 2011 TED Global talk and helped start a company to market it. In October 2011,

    companies and industry groups formed the Li-Fi Consortium, to promote high-speed optical wireless systems. VLC technology was exhibited in 2012 using Li- Fi. By August 2013, data rates of over 1.6 Gbit/s were demonstrated over a single colour LED. In September 2013, a press release said that Li-Fi or VLC systems in general, do not require line-of-sight conditions.

    In October 2013, it was reported Chinese manufacturers were working on Li-Fi development kits. Philips lighting company has developed a VLC system for shoppers at stores. They have to download an app on their smartphone and then their smartphone works with the LEDs in the store. The LEDs can pinpoint where they are at in the store and give them corresponding coupons and information based on path where they are on and what they are looking at.


    The Li-Fi product consists of three primary sub-assemblies:

    • Emitter (including bulb).

    • RF Driver (Radio Frequency)

    • Power supply


        At the heart of LIFI is the bulb sub-assembly where a sealed bulb is embedded in a dielectric material. The dielectric material serves two purposes: Waveguide, Electric field

      2. RF DRIVER

        Power amplifier (PA) assembly that uses an LDMOS (Laterally Diffused Metal Oxide Semiconductor)device. Converts electrical energy into RF power. The PA is designed for hardness and efficiency. The RF driver also contains controls circuit for digital and analog lighting controls.

        7.4 CAPACITY

        With the advent of new technologies like 3g ,4g we are running out of spectrum. Thats why radio waves are now becoming expensive.

        1. WHY ONLY VLC

          Radio Waves

          Infrared Rays

          Visible Rays Ultraviolet Rays

          X- Rays Gama Rays


      3. WORKING

    Li-Fi offers an integrated light source that is straight forward to integrate into a projector. In this example LIFI consists of 5 primary sub-assemblies: Printed circuit board (PCB), RF power amplifier (PA), Bulb, Optics, Enclosure. The operational procedure of LIFI is very simple.If the LED is ON, you transmit a digital 1s , if its OFF you transmit a 0s. The LEDs can be switched ON and OFF very quickly, which gives nice opportunities for transmitting data.

    Fig 3

    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. HENCE WE LEFT WITH THE ONLY THE VISIBLE – LIGHT SPECTRUM.





      150 Mbps


      3 Mbps


      1 Gbps

      Table I :Comparison of transfer speed of various wireless technologies.



      Fig. – 2 Block diagram of Li-Fi system



      There are 1.4 millions cellular radio base stations. Efficiecy of each base station is just 5%.


      Radio waves can penetrate through walls and hence can be intercepted. Anyone with knowledge and bad intention can misuse it.


      We have to switch off mobiles in aircrafts.

      It is also not advisable to use mobiles at petrol pumps.

      10000 times more spectrum than RADIO WAVES. Light boxes are already present, so infrastructure is available already and installed.


      Light is present everywhere.

      Data is present where light is present


      Highly efficient because LED consumes less energy



        The concept of Li-Fi is currently attracting a great deal of interest.It is Efficient alternative to radio-based wireless.

        Li-Fi is an emerging technology which is quick and reliable. Air waves are clogged so lets use light waves.

        So lets proceed to LI FI for a brighter and greener future.

        Some Future Applications of Li-Fi are:-

          1. Education systems:

            Li-Fi is the latest technology that can provide fastest speed internet access.

            So, it can replace Wi-Fi at educational institutions and at companies so that all the people can make use of Li-Fi with the same speed intended in a particular area.

          2. Medical Applications: Operation theatres do not allow Wi-Fi due to radiation concerns. Usage of

            Wi-Fi at hospitals blocks the signals for monitoring equipmnts. So, it may be hazardous to the patient's health. To overcome from this problem , Li-Fi can be used to accessing internet and to control medical equipments. This can even be beneficial for robotic surgeries and other automated procedures.

          3. In Aircrafts: Li-Fi can easily provide high speed internet via every light source. The passengers travelling in aircrafts get access to low speed internet at a very high rate. In aircrafts Li-Fi can be used for data transmission.

          4. Disaster management: Li-Fi can be used as a

        powerful means of communication in times of disaster such as earthquake



        • No more monthly broadband bills.

  • Theoretical speed up to 1 gb per second.

  • A free band that does not need license.

  • less time & energy consumption


    • 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.

    • we will proceed toward the cleaner, greener, safer and brighter future.

    • This may solve issues such as the shortage of radio-frequency bandwidth.

    • Allows internet where traditional radio based wireless isnt allowed such as aircraft or hospitals.

    • This concept promises to solve issues such as the shortage of radio-frequency bandwidth.





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