Visible light communication
Visible light communication (VLC) is a data communications medium using visible light between 400 and 800 THz (780–375 nm). Using visible light is less dangerous for high-power applications because humans can perceive it and act to protect their eyes from damage. VLC is a subset at the optical wireless communications technologies.
The technology uses fluorescent lamps (ordinary lamps, not special communications devices) to transmit signals at 10 kbit/s, or LEDs for up to 500 Mbit/s. Low rate[vague] data transmissions at 1 and 2 kilometres (0.6 and 1.2 mi) were demonstrated. RONJA achieves full Ethernet speed (10 Mbit/s) over the same distance thanks to larger optics and more powerful LEDs.
Specially designed electronic devices generally containing a photodiode receive signals from light sources, although in some cases a cell phone camera or a digital camera will be sufficient. The image sensor used in these devices is in fact an array of photodiodes (pixels) and in some applications its use may be preferred over a single photodiode. Such a sensor may provide either multi-channel communication (down to 1 pixel = 1 channel) or a spatial awareness of multiple light sources.
VLC can be used as a communications medium for ubiquitous computing, because light-producing devices (such as indoor/outdoor lamps, TVs, traffic signs, commercial displays, car headlights/taillights, etc.) are used everywhere.
The history of Visible Light Communications (VLC) dates back to the 1880s in Washington, D.C. when the Scottish-born scientist Alexander Graham Bell invented the photophone, which transmitted speech on modulated sunlight over several hundred meters. This pre-dates the transmission of speech by radio.
More recent work began in 2003 at Nakagawa Laboratory, in Keio University, Japan, using LEDs to transmit data by visible light. Since then there have been numerous research activities focussed on VLC, notably by Smart Lighting Engineering Centre, Omega Project, COWA, ByteLight, Inc.,D-Light Project, UC-Light Centre, and work at Oxford University.
In 2006, researchers from CICTR at Penn State proposed a combination of power line communication (PLC) and white light LED to provide broadband access for indoor applications. This research suggested that VLC could be deployed as a perfect last-mile solution in the future.
In January 2010 a team of researchers from Siemens and Fraunhofer Institute for Telecommunications (Heinrich Hertz Institute in Berlin) demonstrated transmission at 500 Mbit/s with a white LED over a distance of 5 metres (16 ft), and 100 Mbit/s over longer distance using five LEDs.
The VLC standardization process is conducted within IEEE Wireless Personal Area Networks working group (802.15).
Recently, VLC-based indoor positioning system has become an attractive topic. ABI research  forecasts that it could be a key solution to unlocking the $5 billion "indoor location market". Publications have been coming from Nakagawa Laboratory, COWA at Penn State and other researchers around the world.
Another recent application is in the world of toys, thanks to cost-efficient and low-complexity implementation, which only requires one microcontroller and one LED as optical front-end.
In October 2014, Axrtek launched a commercial bidirectional RGB LED VLC system called MOMO that transmits down and up at speeds of 300 Mbit/s and with a range of 25 feet.
- Optical Wireless Communications
- Fiber-optic communication
- Free space optics
- IrDA — Same principle as VLC but uses infrared light instead of visible light
- Free-space optical communication
- "Image Sensor Communication". VLC Consortium.[dead link]
- "Lighthouse Sub Project". VLC Consortium.[dead link]
- "About Visible Light Communication". VLC Consortium.[dead link]
- "Intelligent Transport System – Visible Light Communication". VLC Consortium.[dead link]
- M. Kavehrad, P. Amirshahi, “Hybrid MV-LV Power Lines and White Light Emitting Diodes for Triple-Play Broadband Access Communications,” IEC Comprehensive Report on Achieving the Triple Play: Technologies and Business Models for Success, ISBN 1-931695-51-2, pp. 167-178, January 2006. See publication here
- "500 Megabits/Second with White LED Light" (Press release). Siemens. Jan 18, 2010.
- "St. Cloud first to sign on for new technology" (Press release). St. Cloud Times. Nov 19, 2010.
- Yoshino, M.; Haruyama, S.; Nakagawa, M.; , "High-accuracy positioning system using visible LED lights and image sensor," Radio and Wireless Symposium, 2008 IEEE , vol., no., pp.439-442, 22-24 Jan. 2008. ByteLight filed a patent on a light positioning system using LED digital pulse recognition in March 2012. In January 2013 it publicly piloted this technology for the first time at the Museum of Science in Boston. See publication here
- S. Horikawa, T. Komine, S. Haruyama and M. Nakagawa,”Pervasive Visible Light Positioning System using White LED Lighting”, IEICE, CAS2003-142,2003.
- Zhang, W.; Kavehrad, M.; , "A 2-D indoor localization system based on visible light LED," Photonics Society Summer Topical Meeting Series, 2012 IEEE , vol., no., pp.80-81, 9–11 July 2012. See publication here
- Lee, Yong Up; Kavehrad, Mohsen; , "Long-range indoor hybrid localization system design with visible light communications and wireless network," Photonics Society Summer Topical Meeting Series, 2012 IEEE , vol., no., pp.82-83, 9–11 July 2012. See publication here
- Panta, K.; Armstrong, J.; , "Indoor localisation using white LEDs," Electronics Letters. vol.48, no.4, pp.228-230, February 16, 2012.See publication here
- Hyun-Seung Kim; Deok-Rae Kim; Se-Hoon Yang; Yong-Hwan Son; Sang-Kook Han; , "Indoor positioning system based on carrier allocation visible light communication," Quantum Electronics Conference & Lasers and Electro-Optics (CLEO/IQEC/PACIFIC RIM), 2011 , vol., no., pp.787-789, Aug. 28 2011-Sept. 1 2011. See publication here
- Giustiniano D.; Tippenhauer N. O.; Mangold, S.; , "Low-Complexity Visible Light Networking with LED-to-LED Communication" Wireless Days, 2012 IFIP, (pp. 1-8), 21-23 Nov. 2012., Best Paper Award See publication here
- Xin Huang; Bangdao Chen; A.W. Roscoe; , "Multi−Channel Key Distribution Protocols Using Visible Light Communications in Body Sensor Networks", Computer Science Student Conference 2012, (pp. 15), Nov. 2012., See publication here
- Xin Huang; Shangyuan Guo; Bangdao Chen; A.W. Roscoe; , "Bootstrapping body sensor networks using human controlled LED−camera channels", Internet Technology And Secured Transactions‚ 2012 International Conferece For, (pp. 433-438), Dec. 2012., See publication here
- P. Haigh, F. Bausi, Z. Ghassemlooy, I. Papakonstantinou, H. Le Minh, C. Fléchon, and F. Cacialli, "Visible light communications: real time 10 Mb/s link with a low bandwidth polymer light-emitting diode," Opt. Express 22, 2830-2838 (2014) See publication here
- Axrtek MOMOAxrtek, Inc.
- David G. Aviv (2006): Laser Space Communications, ARTECH HOUSE. ISBN 1-59693-028-4.
- IEEE 802.15 WPAN Task Group 7 (TG7) Visible Light Communication