Visible light communication

Visible Light Communications, VLC or short, is a data transfer technology. In this case, data or information are transmitted via the optical transmission medium. The frequency of the light used for the transmission is in this case in the visible range between 400 THz (750 nm; 1 THz = 1000 GHz ) and 800 THz (375 nm).

Technology

To generate the needed light fluorescent lamps or LEDs are used. If fluorescent lamps are used, data rates up to 10 kbit / s can be achieved. When LEDs are used currently (August 2011) can be achieved s up to 800 Mbit / s. On the receiver side, a photodetector converts the optical signals back into current pulses.

Use

Due to the specific properties of the light used, this technology could be for use as a transmission technology for " ubiquitous computing " are, as the light of the appropriate wavelength is considered completely safe and can be used virtually anywhere. In addition, the light waves can be easily defined by each optical shielding in the spatial spread.

An advantage of this is also the royalty-free redistribution of the corresponding frequencies.

History

The first VLC devices were developed in 2003 in the Nakagawa Laboratory of Keio University in Japan.

In January 2010, a team of researchers succeeded Siemens and Fraunhofer Heinrich Hertz Institute in Berlin over white LEDs data at up to 500 Mbit / s to be transmitted over a distance of 5 meters. A standardization is done in IEEE 802.15.7.

Li -Fi

2011 coined the German researcher Harald Haas on a presentation at the California TED Conference (Technology, Entertainment, Design ) based on Wi -Fi the term Li -Fi for the latest VLC generation later in the year was the "Li - Fi consortium "among others with the Fraunhofer Institute for Photonic Microsystems, which promote a standard of the same world and wants to bring to market.