New Trend: Visible Light Communications
Visible light communication (VLC) is a data communications medium using visible light between 400 THz (780 nm) and 800 THz (375 nm). Visible light is not injurious to vision.
Visible Light Communication uses light emitting diodes (LEDs), for the dual role of illumination and data transmission. Using the visible light spectrum, which is free and less crowded than other frequencies, wireless services can be piggy-backed over existing lighting installations. With this leading edge technology, data including video and audio, internet traffic, etc, can be transmitted at high speeds using LED light.
Most wireless communications today are produced from radio waves (RF) generated from electronic equipment. “WI-FI”, “3G Networks” and “Bluetooth” are examples of this applied technology. Even the fastest of these RF data transmission networks cannot compete with the potential of visible light transmission speeds. The fastest networks today are equipped with fiber optic cabling and equipment. The next generation of wireless networks will use light as its transmission medium because of these superior attributes.
VLC technology has the potential to deliver data transfer rates in excess of hundreds of megabits per second. Light radiation neither constitutes nor suffers from electromagnetic interference (EMI) making VLC a very attractive technology in places/environments where electromagnetic interference (EMI) is an issue, such as in hospitals and in aircraft. In addition, where security of local communication is important eg defence and fanance applications, VLC technology offers a secure medium for communication in an office/building environment.
Specially designed electronic devices generally containing a photodiode receive signals from such 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 sensor may provide either a multi-channel communication (down to 1 pixel = 1 channel) or a spatial awareness of multiple light sources.
The incorporation of VLC components into everyday technology is being investigated by a number of universities, corporations and organisations worldwide, and has already resulted in the creation of the Japan Electronics and Information Technology Industries Association’s JEITA standards (2007) for a “visible light ID system”, and a Specification Standard in 2008 by the Visible Light Communications Consortium (VLCC) - as a result of its joint cooperative agreement with the Infrared Data Association (IrDA).
The Institute of Electrical and Electronics Engineers (IEEE) Wireless Personal Area Networks working group 802.15.7 Task Group 7 is also developing a standard for VLC technologies that should be finalised by the end of 2010, whilst the EU-funded OMEGA project is investigating ways in which such technology can be incorporated into home networks.
Research in this area is being undertaken by, amongst others: Casio, Eurescom, France Telecom, NEC Corporation, Orange, Panasonic, Samsung, Sharp, Siemens AG, Telefonica, Toshiba, Universita di Roma, Universität Dortmund, Universität Ilmenau, University of Athens, University of California, and the University of Oxford.
Some of the VLC Applications:
A wide range of applications would benefit from using novel visible light communications:
WiFi Spectrum Relief - Providing additional bandwidth in environments where licensed and/or unlicensed communication bands are congested
Smart Home Network – Enabling smart domestic/industrial lighting; home wireless communication including media streaming and internet access
Commercial Aviation – Enabling wireless data communications such as in-flight entertainment and personal communications
Hazardous Environments- Enabling data communications in environments where RF is potentially dangerous, such as oil & gas, petrochemicals and mining
Hospital and Healthcare – Enabling mobility and data communications in hospitals Defence and Military Applications – Enabling high data rate wireless communications within military vehicles and aircraft
Corporate and Organisational Security – Enabling the use of wireless networks in applications where (WiFi) presents a security risk
Underwater Communications – Enabling communications between divers and/or remote operated vehicles Location-Based Services – Enabling navigation and tracking inside buildings.