IJRIT International Journal of Research in Information Technology, Volume 2, Issue 4, April 2014, Pg: 166- 170
International Journal of Research in Information Technology (IJRIT)
www.ijrit.com
ISSN 2001-5569
Light-Fidelity: A Reconnaissance of Future Technology Mohit Madan, Stela Sarkar Computer Science, Maharshi Dayanand University Khentawas, Farrukh Nagar-122506, Gurgaon, Haryana, India
[email protected],
[email protected] Abstract— This document gives formatting instructions for authors preparing papers for publication in the Proceedings of an IEEE conference. The authors must follow the instructions given in the document for the papers to be published. You can use this document as both an instruction set and as a template into which you can type your own text. Keywords— Wireless-Fidelity (Wi-Fi), Light-Fidelity (Li-Fi), Light Emitting Diode (LED), Line of Sight (LOS), Visible Light Communication (VLC)
I. INTRODUCTION Li-Fi is a transmission of data through illumination by taking the fibre out of fibre optics by sending data through a LED light bulb that varies in intensity faster than the human eye can follow. Li-Fi comprises a wide range of frequencies and wavelengths, from the infrared through visible and down to the ultraviolet spectrum. It includes sub-gigabit and gigabit-class communication speeds for short, medium and long ranges, and unidirectional and bidirectional data transfer using line-of-sight or diffuse links, reflections and much more. It is not limited to LED or laser technologies or to a particular receiving technique. Li-Fi is a framework for all of these providing new capabilities to current and future services, applications and end users. This 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 digital 1; if its off you transmit 0. The LEDs can be switched on and off very quickly, which gives nice opportunities for transmitting data.” The LED intensity is modulated so rapidly that human eye cannot notice, so output appears constant. The technology was demonstrated at the 2012 Consumer Electronics Show in Las Vegas.
Fig. 1 Overview of Li-Fi
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IJRIT International Journal of Research in Information Technology, Volume 2, Issue 4, April 2014, Pg: 166- 170
II. DESIGN OF LI-FI Li-Fi architecture consists of numbers of Led bulbs or lamps, many wireless devices such as PDA, Mobile Phones, and laptops. Important factors we should consider while designing Li-Fi as following: • • •
Presence of Light Line of Sight(LOS) For better performance use fluorescent light and LED
As shown in the figure 2 streaming content must have proper integration with server and internet network, so that it is easily possible to work efficiently.
Fig. 2 Architecture of Li-Fi
III. IMPLEMENTATION OF LI-FI Li-Fi is typically implemented using white LED light bulbs at the downlink transmitter. These devices are normally used for illumination only by applying a constant current. However, 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. The operational procedure is very simple, if the LED is on, you transmit a digital 1, if it’s off you transmit 0. The LEDs can be switched on and off very quickly, which gives nice opportunities for transmitting data. Hence all that is required is some LEDs and a controller that code data into those LEDs. All one has to do is to vary the rate at which 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 light’s frequency with each frequency encoding a different data channel. Such advancements promise a theoretical speed of 10 Gbps which means one can download a full high-definition film in just 30 seconds. 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.
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IJRIT International Journal of Research in Information Technology, Volume 2, Issue 4, April 2014, Pg: 166- 170
Fig. 3 Implementation of Li-Fi
IV. VALUES OF LI-FI • A free band that does not need license. • High instantaneous cost but very low maintenance cost • Cheaper than Wi-Fi. • Theoretical speed up to 1 GB per second: Less time and energy consumption. • No more monthly broadband bills. • Lower electricity costs. • Longevity of LED bulb: saves money. • Light doesn’t penetrate through walls: secured access. • Traffic Updates. • Game Consoles. • Television interaction. • Easy to use. • Harmless. • Fast data transfer. • • •
V. LIMITATIONS OF LI-FI The main problem is that light can’t pass through objects, so if receiver is inadvertently blocked in any way, then the signal will immediately cut out. “ If the light signal is blocked, or when you need to use your device to send information- you can seamlessly switch back over to radio waves”. Reliability and network coverage are the major issues to be considered by the companies while providing VLC services. Interference from external light source 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 can be complemented by large-scale implementation of VLC through adopting VLC technology will reduce further operating costs like electricity charges, maintenance charges etc.
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IJRIT International Journal of Research in Information Technology, Volume 2, Issue 4, April 2014, Pg: 166- 170
•
• •
This research report categorizes the global VLC technology market; based on component, applications and geography. Li-Fi uses light emitting diodes (LEDs) which are rapidly gaining in popularity for standard light bulbs and other domestic and commercial purposes. They are expected to be ubiquitous in 20 years. VLC is not in competition with Wi-Fi, it is a complementary technology that should eventually help free up much needed space within the radio wave spectrum. We still need Wi-Fi we still need radio frequency cellular systems. You can’t have a light bulb that provides data to a high speed moving object or to provide data in a remote area where there are trees and walls and obstacles behind. Best hotspots are : The remote control devices under the ocean: radio wave doesn’t work there. Petrochemical plants: radio wave data transmission is not secured there. Hospitals: for medical purposes. Street lights, traffic signals: for traffic purposes. Aircraft cabins: for emergency conversations.
VI. COMPARISION BETWEEN LI-FI AND WI-FI
VII. CONCLUSION Li-fi is certainly not useless, but it has certain inherent limits for the technology. Li-Fi may not be able to replace conventional radios altogether, but it could turbo charge the development of wireless television and make it easier to throw a wireless signal across an entire house. At present , finding the ideal position for a wireless router is something of a divine art. If the signal could be passed via VLC from point A to point B inside a home, small local routers at both points could create local fields with less chance of overlapping and interfering with each other. Large scale areas that are saturated with radio signals or that doesn’t permit them for security reasons could use Li-Fi as an alternate high-speed wireless network solution. Li-Fi is attracting a great deal of interests, not least because it may offer a genuine and very efficient alternative to radio based wireless. As a growing number of people and their many devices access wireless internet, the airwaves are becoming increasingly clogged, making it more and more difficult to get a reliable, high speed signal. This may solve issues such as shortage of radio-frequency bandwidth and also allow internet where traditional radio based wireless isn’t allowed such as aircraft or hospitals.
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IJRIT International Journal of Research in Information Technology, Volume 2, Issue 4, April 2014, Pg: 166- 170
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