Li-Fi âFuture of Wireless
Transcription
Li-Fi âFuture of Wireless
IJSART - Volume 1 Issue 5 –MAY 2015 ISSN [ONLINE]: 2395-1052 Li-Fi –Future of Wireless Ashvanth Ramesh Kumar1, Aarthi R2 Department of Computer Science 1 Illinois Institute of Technology,Chicago,USA 2 RMD Engineering College, Tamil Nadu, India Abstract- Light-Fidelity in short called as Li-Fi was proposed by a Germanphysicist Harald Hass.Li-Fi is considered as the future of wireless technology. It uses light as a transmission medium which in turn results in the data transmission through illumination. The intensity of an LED light bulb varies much faster which cannot be captured by human eye.This paper mainly focuses on developing a Li-Fibased system and analyzes its performance with respect toexisting technology. Wi-Fiis very much suitable to provide internet access within the buildings and on the other hand Li-Fi is ideal for high density wireless data coverage in confined area. Li-Fi can be considered as a Light based Wi-Fi and has a better data rates, security and efficiency when compared to Wi-Fi.Li-Fi uses only LED lamps whichare easily available at low cost and this in turn helps us to have internet access through street lights to high speed cars which can communicate through their headlights. This technology is mainly focused for laptops,PDA gadgets and smart phones which will access to the internet with the help of LED lamps fitted in the room. Keywords- Light-Fidelity (Li-Fi), Light Emitting Diode (LED), Wireless-Fidelity (Wi-Fi). I. INTRODUCTION Internet is playing a vital role in our day today activities. People are connecting to network either through wired medium or through wireless medium. We need to transfer data from one system to another to complete our activity. When multiple system access the same access point the data transfer rate will be reduced because only a fixed bandwidth is available to access the internet. For example, In a Mall there will be a free Wi Fi zone but the network quality will be very minimal because many people access the internet which in turn results in poor internet access. transmission medium which in turn results in the data transmission throughillumination. The intensity of an LED light bulb (shown in Fig. 1)varies much faster which cannot be captured by human eye. A German physicist, Harald Hass introduced the concept called D light which is referred to as data through Illumination. He called it as D light, which can produce a data rate of higher than 10 megabits per second. It is then later called as Li Fi. Li-Fi is a part ofvisible light communication (VLC) PAN IEEE 802.15.7 standard. Li Fi offers a larger frequency band of around 300 THz but on the other hand RF communications can give a frequency band of 300GHz. Li-Fi uses only LED lamps which are easily available at low cost and this in turn helps us to have internet access through street lights to high speed cars which can communicate through their headlights.[2] This technology is mainly focused for laptops, PDA gadgets and smart phones which will access to the internet with the help of LED lamps fitted in the room.Li Fi can also be used in Military areas where security is a primary concern.[3] Fig 2 Overview of Li-Fi II. DESIGN OF LI-FI Li-Fi architecture is designed to have more numbers of Light emitting diodes or lamps, and numerous wireless devices such as Smart Phones, Laptops, and PDA gadgets.Primary factors which should be taken care while designing Li-Fi are Fig. 1. Li-Fi bulb The problem can be solved by using Li-Fi technology. Li-Fi denotesLight-Fidelity.It uses light as a Page | 94 Presence of Light Line of Sight (Los) Fluorescent light &light emitting diodes should be used to have better performance www.ijsart.com IJSART - Volume 1 Issue 5 –MAY 2015 ISSN [ONLINE]: 2395-1052 IV. FUNCTION OF BLUB SUB ASSEMBLY Fig. 3 Architecture of Li-Fi As shown in figure 3, the efficiency of the Li Fi lies in the streaming content integration with server & internet network. As shown in the Block diagram of Li-Fi subassemblies, the sealed bulb is embedded in a dielectric material. This Li Fi makes the design more reliable. The main purposes of using the dielectric material are: 1. It acts as a waveguide for the RF energy transmitted by the RF power amplifier circuit. 2. As a concentrator for electric field that mainly focuses on energy in the bulb. III. CONSTRUCTION OF LI-FI SYSTEM Li-Fi is called as Light Bases Wi Fi and it is very fast and economical optical version of Wi-Fi.[8] Li Fi uses Visible Light Communication (VLC).VLCuses visible light between 400THz (780 nm) and 800 THz (375 nm) as optical carrier fordata transmission and illumination.Li Fi mainly consists of: a) Transmission source:A high brightness white Fluorescent light or light emitting diodes. Fig 5 Bulb sub-assembly V. WORKING OF LI-FI b) ReceivingElement: A silicon photodiode which has a good response to visible light. The sub-assemblies of Li Fi are as follows: • Bulb • PA (RF power amplifier circuit) • PCB (Printed circuit board) • Enclosure Electrical inputs and outputs of the lamp are controlled by PCB and the other lamp functions are controlled by the micro controller. Solid-state PA generates the RF (radio-frequency) signal and this in turn helps in driving electric field about the blub.[11]The blub contents are vaporized to a plasma state due to the concentration of energy in the electric field and this controlled plasma produces an intense source of light. Fig.4 Block diagram of Li-Fi sub-assemblies Page | 95 Light-emitting diodes act as a transmission source for the Li Fi technology. Digital 1 is transmitted if the LED is switched ON and Digital 0 is transmitted if the LED is switched OFF. The LED lamps can be turned ON and OFF instantly which helps in efficient transmission of data through light. [9] Li Fi has a light emitter on one end, for example, Light - emitting diodes, and a photo detector on the other end. Binary one is registered when the LED is switched ON by the photo detector and when the LED is switched OFF, Binary zero is registered.[11] Different data rates can be obtained when array of LED‟s with different colors is used. Fig. 6 Block diagram of Li-Fi system www.ijsart.com IJSART - Volume 1 Issue 5 –MAY 2015 When Light-emitting diodes are switched ON and OFF we will be able to generate different combinations of Zeros and One. Human eye cannot detect the intensity of the LED lamps which varies rapidly.[16]Light-emitting diodes commonly referred to as LEDs are used in our day today commodities like street lights, car head lights, remote control units and other applications. The data rates can be varied by switching ON and OFF the LED lamp which helps in the transmission information and this is called as Visible Light Communication (VLC).[12]Li-Fi is now part of visible light communication (VLC) PAN IEEE 802.15.7 standard. Fig.7 Li-Fi system connecting devices in a room. The above figure shows how Li Fi i.e. Light can used a transmission medium. All the gadgets like PDBA, Laptops should be in the Line of sight to the electric blub to achieve high data rate. VI. COMPARISION WITH EXISITING WIRELESS TECHNOLOGY Li Fi is a part of visible light communication which helps in high transfer rate.[15] Li Fi can be treated as a Light Based Wi Fi. Li Fi uses light whereas Wi Fi uses the radio spectrum. Li-Fi is ideal for high density wireless data coverage in confined area and Wi Fi is used for wireless coverage and the coverage areas are confined within the buildings. Table I shows a comparison of transfer speed of various Wireless technologies. Table II shows a comparison of various Technologies that are used for connecting to the end user. ISSN [ONLINE]: 2395-1052 WI Gig Giga-IR Li-Fi Future Wireless System 2 Gbps 1 Gbps >1Gbps TABLE II.COMPARISON OF SPEED OF VARIOUS WIRELESSES TECHNOLOGIES Li Fi Characteristics Blue tooth WiFi Frequency 2.4 Hz 2.4 Hz – 5GHz No frequency for light Range 10 meters 100 meters Based on LED light falling Data Transfer rate 800 kbps 11Mbps >1Gbps Operating Band ISM Band RF Band Visible Light Band Working Concept MasterSlave Various Topologies Direct Binary Data Serving The above table gives us the compare the various features present in the existing wireless technology and that in turn compared with Li-Fi which is considered as the future of wireless. VII. MERITS OF LI-FI Li Fi technology has the fastest data transfer rate and we can download HD videos and large amounts of data‟s in GB within fraction of seconds.[17] Li Fi technology mainly depends on the LED lamps or other light sources for the transfer of data. Wi Fi has more number of limitations and this has been overcome by Li Fi. The advantages of Li Fi technology are as follows: TABLE I.COMPARISON OF SPEED OF VARIOUS WIRELESS TECHNOLOGIES Technology Speed Current Wireless System a) Capacity: Wi Fi uses the radio spectrum and we are running out of spectrum availability. On the other hand, Li Fi which uses Light has wider bandwidth when compared to that of radio waves. So, Li Fi has a wider bandwidth and better capacity. Wi-Fi – IEEE 802.11n Bluetooth IrDA b) Efficiency:The efficiency of the radio wave base station is only 5% because more amount of energy is spent on cooling the base station than in the transmission. On the other hand, Li Page | 96 150 Mbps 3 Mbps 4 Mbps www.ijsart.com IJSART - Volume 1 Issue 5 –MAY 2015 ISSN [ONLINE]: 2395-1052 Fi uses LED lamps for data transmission which consumes less energy and the overall efficiency is also high. c) Availability: Radio spectrum cannot be used in all places but Li Fi uses Light as a source for data transmission and light bulbs are used universally. d) Security: Light waves in LI Fi cannot not penetrate through walls. So, they can„t be misused and can be used for secure purposes. VIII. SHORTCOMINGS OF LI-FI Some of the short comings of using Li Fi technology are as follows: A. External light cannot travel into walls and other opaque materials. B. Li-Fi enabled end device (through its inbuilt photoreceiver) will never be as fast and handy as a Wi-Fi enabled device in the open air. C. Always works in the Direct Line of Sight . Fig.8 Smarter Power Plants d) Airlines: Internet access in the aircrafts is very minimal and it is offered at high price. Wi Fi usage is limited in aircrafts because it may get interfered with the navigational systems of the pilots. So, this interference can be overcome by using Li Fi which provides the high speed internet via the light sources present inside the cabin with minimal cost. [21] IX. APPLICATIONS OF LI-FI Li Fi uses LED lamps for data transmission and has numerous applications. The future applications of Li Fi are as follows: A) Educationsystems: Li-Fi provides us high speed internet access. So, Wi Fi can be replaced by Li Fi in education system. Using Li-Fi, we can listen to Online lectures easily without any buffering time.[20] b) Health technologies: Wi Fi should not be used in hospitals because the radio spectrum blocks the signals of the monitoring equipment. Due to radiation concerns, Wi FI is not allowed in Operation theatres (OTs). [7] Li Fi can be used in hospitals without affecting patient‟s health. This helps in involving robots to perform surgeries and other automated process. c) Power Plants: Wi-Fi and many other radiation or radio waves are harmful for sensitive areas like thoseof power plants especially the atomic power plants. Nuclear power plants need fast, some wireless technology to monitor things like demand, grid integrity and core temperature and inter-connected data systems. The efficiency of the plant can be improved if monitoring is done well. [3]Li Fi can provide more accurate data and helps in increasing the overall effectiveness of the system. Page | 97 Fig.9Airlines e) Under Sea Working: Li Fi has a major role in under sea communications. Underwater Rovers, which is also called toys of treasure seekers, operate from long cables.ROV receive signals from their pilots above. The radio communication work efficiently in a small area. [5]If Li Fi is used they can use a high-powered lamp and can explore more. The explorers can even interact with each other using their headlights and can obtain their orders from the source. f) Traffic management: LED lamps acts as a primary source for Li Fi.LED lamps are present in the headlights of the car and helps in managing the traffic and accidents numbers. LED car lamps can also alert drivers about the car/vehicle which is near to it. X. CONCLUSION Li-Fi is not limited to LED or laser technologies and has wide range of operating frequencies and wavelength. Li Fi supports both unidirectional and bidirectional data transfer using line-of-sight. If Li Fi is put into practice, every LED lamp will acts as a Wi Fi hotspot and helps in transmission of wireless data. This will help in the safer, cleaner andecowww.ijsart.com IJSART - Volume 1 Issue 5 –MAY 2015 friendlyfuture. The demand for wireless internet is keep on increasing due to more number of smart phones into the market and this clogs the available radio spectrum. Li Fi has a broader application area where Wi Fi fails to support. But, one of the major short comings is Li Fi works only on the Direct Line of Sight. ISSN [ONLINE]: 2395-1052 [7] http://articles.economictimes.indiatimes.com/2013-0114/news/36331_1_data-transmission-trafficvisiblespectrum [8] http://www.extremetech.com/extreme/147339-micro-ledlifi-whereevery-light-source-in-the-world-is-also-tv-andprovides-gigabit-internetaccess XI. FUTURE ENHANCEMENTS Li Fi system can be further enhanced by using array of LED‟s which helps in parallel data transmission and the light frequency can be varied by using mixture of red, green and blue LEDs. We can expect a speed of about 10 Gbps by using Li Fi technology and this result in download of high definition film with in fraction of seconds. 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TED Global. Edinburgh, Scotland. [6] Vucic, J. and Langer, K.-D., “High-speed visible light communications: State-of-the-art,” in [Optical Fiber Communication Conference and Exposition (OFC/NFOEC), 2012 and the National Fiber Optic Engineers Conference] Page | 98 [9] Li-Fi (Light Fidelity)-The future technology In Wireless Communication NehaSingh, International Journal of advances in computing & communications, vol.1, 2013 www.ijacc.org [10] http://www.good.is/posts/forget-wifi-it-s-lifi-internetthrough-lightbulbs [11] “New Epoch of wireless communication: Light Fidelity” IJIRCCE, volume 1,issue 2,April 2013. [12] http://www.ispreview.co.uk/index.php/2013/01/tiny-ledlights-set-todeliver-wifi-styleinternetcommunications.html [13] http://www.newscientist.com/article/mg21128225.400will-lifi-be-thenew-wifi.html [14] http://groupivsemi.com/working-lifi-could-be-availablesoon/ [15] H. Haas, “Wireless Data from Every Light Bulb”, TED Website, Aug. 2011.[Online]. vailable:http://bit.ly/ted_vlc. [16] Azhar, A., Tran, T., and O‟Brien, D., “A Gigabit/s Indoor Wireless Transmission Using MIMO-OFDM VisibleLight Communications,” IEEE Photonics Technology Letters 25, 171–174 (Jan.15 2013). [17] Technopits.blogspot.comtechnology.cgap.org2012/01/11/ a-li-fi-world/ [18] Li-Fi – Internet at the Speed of Light, by Ian Lim, the gadgeteer,dated 29 August 2011. [19] “Visible-light communication: Tripping the light fantastic: A fast and cheap optical version of Wi-Fi is coming". TheEconomist. 28 January 2012. Retrieved 22 October 2013. [20] ”Visible-light communication: Tripping the light fantastic: A fast and cheap optical version of Wi-Fi is www.ijsart.com IJSART - Volume 1 Issue 5 –MAY 2015 ISSN [ONLINE]: 2395-1052 coming”, Economist,dated 28Jan 2012 [21] An IEEE Standard for Visible LightCommunicationsvisiblelightcomm.com, dated April 2011.Tsonev, D.; Sinanovic, S.; Haas, Herald (15 September 2013). "Complete Modeling of Nonlinear Distortion in OFDM-Based Optical Wireless Communication". IEEE Journal of Light wave Technology 31 (18): 3064– 3076.doi:10.1109/JLT.2013.2278675 ABOUT THE AUTHORS Ashvanth did his Bachelor‟sDegree in Electronics and Communication and has a keen interest in the field of Electronics and Computer Science. He has an industrial experience of around 2.5 years and Currently doing his Masters in Computer Science at Illinois Institute of Technology, Chicago, USA. Aarthi did her Bachelor‟s Degree in the field of Electronics and Communication and has published many research papers. She did her Masters in the field of Applied Electronics and working as a Assistant Professor in RMD Engineering for past 4 years and handled many papers on Digital Communication, Control Systems. She is also acting as research guide for her students in the field of VLSI and Communication Systems. Page | 99 www.ijsart.com