LiFiHISTORY • GrahamBell(1880) Photophone • Carl Zeiss Jena developed light speaking device. • Invention of Lasers revolutionized free sapce optics in 1960. • Gfeller (1978) – Wireless communication using optical spectrum • Nakagawa laboratory (2003)- Transmission with LeDs. • VLCC establishment in 2003 • Jan 2010 : researchers from Siemens and Fraunhofer Institute of Telecomm. demonstrated transmission at 500mbps • December 2010 : St. Cloud Minnesota • July 2011 : live demonstration was presented VLC ●COMPARISON OVER IR ●COMPARISON OVER RF ●WHY LIFI? . television remote controls and even some newer mobile phones • Infrared Data Association (IrDA) has standardized over 30 specifications VLC over IR • Narrow beam of VLC over IR – Less opportunity for eavesdropping – Decrease in adjacent device interference – beam blocked from illuminating more than one device at once.Infrared Communication Infrared: • Used in devices such as notebook computers. • Installation – Easier and cost effective • Obstruction – VLC : Less obstruction – LOS component dominates thus effect of multipath is small • Signal-to-noise ratio (SNR) – High SNR obtainable in VLC as a consequence of the illumination requirements. . • Power Efficiency – VLC eliminates severe power efficiency loss • Safety – IR causes potential visual safety problems . interfere with sensitive equipment VLC over RF • Health Concerns – RF : radiation damage – VLC : no health concerns.OVER RF RADIO FREQUENCY – Wide usage in WLAN networks – Compromise information. no safety regulations • Carbon-dioxide footprint – VLC : Significantly reduced due to its low energy consumption . • Radio wave interference – VLC : no interference with RF based systems exist • Communication link – VLC: has better channel condition than Radio Frequency (RF) • Frequency allocation – VLC : Doesn’t have any frequency allocation issues present in RF • Bandwidth – VLC: Is not limited . Why Li-Fi? • Visible Light Communication is not regulated . an ideal ubiquitous data transmitter .• Visible light LED will be used everywhere – The extensive use of LEDs render. • Image sensors can be used as receivers – Accurate direction of incoming vector – Aids in applications where RF cannot be deployed . What is Li-Fi? . • Visible Light Communication through LEDs. . • Send data by flashing light at speeds-0s &1s • Data rates upto 500Mbps • Employs semiconductor devices containing a photodiode. • Key aspect : Intensity modulation • Termed as directdetection • Light Source – Optical Access Point • Employs OFDM . Methods of VLC . METHOD I . . METHOD II . Principles of communication using image sensor . . WHITE LEDs • Long life span • High lighting efficacy and color rendering index • Easy installation. • No light pollution • Low light decay. • Low maintenance cost • Energy saving • High safety • Start immediately. • Fast response . • Green initiative. • Low heat productivity. TECHNICAL ASPECTS OF THE SYSTEM DESIGN Typical Block Diagram of a VLC system . • Viable modulation is intensity modulation (IM). .Modulation/ Demodulation Techniques Optical Carrier Schemes: • Optical coherent receivers: – Detect the optical carrier phase. – Require a local oscillator. much simpler to implement than coherent detection. signal power is very less. • Practical down-conversion technique is direct detection (DD). optical mixer and optical filter. • LEDs emit incoherent light. additional receiver complexity • Orthogonal Frequency Division Multiplexing(OFDM) – Inherent robustness of OFDM against multipath effects – Support high data rates without the need for complex channel equalizers – Offers high bandwidth efficiency – Can easily combine with TDMA and FDMA . Pulse Position Modulation(PPM) – widely used in RF and IR communication systems – Multipath delay – Channel delay spread(ISI) – limits data rate to 10Mbps – To overcome .Electrical Modulation Techniques • On-Off keying(OOK) . The peak of each signal coincides with trough of other signals .OFDM • Wireless data transmission technology • Carrier centers are put on orthogonal frequencies • ORTHOGONALITY . Modulation • Subcarriers are spaced by Δf=1/Ts • Total passband bandwidth will be B ≈ N·Δf (Hz) . • Two standards introduced by VLCC(2008): – To avoid fragmentation of proprietary protocols 1. promotion. ubiquitous telecommunication system using visible light through the activities of market research. . JEITA CP-1221 : • Mainly used for transmitting information on identification and arbitrary data. JEITA CP-1222 : • Differs from JEITA CP-1221 in that it is supposed to be only used for communication purposes and is slightly more specific in its suggestions. 2. and standardization.STANDARDIZATION EFFORTS • Visible Light Communications Consortium(VLCC) Purpose : – To realize safe. 7 (2011): – IEEE Standard for Local and Metropolitan Area Networks – Was developed by Task Group 7 (TG7) – Proposes PHY/MAC Specification Fig : IEEE 802.15.802.15.• IEEE standard .7 Standard Specification of MAC and PHY layers . ApplicationsPersonal Area Communication • Download of needed information for digital signage applications IrDA and VLCC have been working together since Sept 2008 for a visible light communication using IrDA protocol stacks . Japan Based on 100 Mbps infrared LAN system (Standard proposed by ICSA of ARIB) .• 100 Mbps Full-duplex multi-access VLC system Implemented at Nakagawa Laboratory. • High-Speed Parallel Wireless VLC system using 2D Image Sensor and LED Transmitter By Keio University and Sony Kihara Laboratory . • Communication using LED spotlight “Hikari Guide System” by Shimizu Corporation. Japan . • Visible light information broadcast system Prototype made by NEC and Matsushita Electric Works. members of VLCC . • Application of VLC to ITS(Intelligent Transport System) By VLCC and The Japan Traffic management Technology Asstn . • Information broadcast system using LED traffic lights The Nippon Signal Co.Ltd and VLCC . • Multiple transmission using multiple colors Joint project of Keio University and JVC “Sound Spot” . Applications that enable users to know their locations in accuracy of several meters • Global location service that uses VLC Prototype made by NEC and Matushita Electric Works . • Flow planning survey system for a store Nakagawa laboratories . Inc . • Flow planning survey system for a store . • Three dimensional position measuring system using VLC Applications of location determination(in several millimeter accuracy) . • Accurate position detection of a transmitter or a receiver . Applications that use augmented reality • Augmented Reality of real world image added with personal info . • Lighthouse VLC . Oct 2010 .Applications where radio waves cannot be used • Underwater VLC By Rise. Keio university. Inc. Nakagawa lab. • Charter members : a leading group of international technology companies and research institutions in optical communication technology.LiFi Consortium • Non-profit organization devoted to introduce optical wireless technology. • Purposes: – Promote optical wireless communications up to the multigigabit range – Inform potential implementers of the companies and resources available to help them achieve their product goals – Create whole solutions in anticipation of customer needs – Coordinate with standardization groups and other industry . It offers users virtually unlimited communication capability. how we work. and how we communicate. Thank you. this technology is predicted to revolutionize the commtn system being affordable and contention free. high security. .Wireless communication using visible light will change how we live. biologically friendly communications network it can allow the creation and expansion of seamless computing applications using very large bandwidth high-frequency pulsed light instead of radiowaves and microwaves. In the near future. Being a ultra high-speed.