The future of networking may mean streaming high-definition movies at blazing fast speeds and the routers are the lights in the room.
Scientists at the Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute HHI in Berlin, Germany, have developed a new transfer technology for video data and were able to transfer data at a rate of 100 megabits per second (Mbit/s), without any losses, using LEDs in the ceiling that light up more than ten square meters (90 square feet).
"This means that we transferred four videos in HD quality to four different laptops at the same time," says Dr. Anagnostis Paraskevopoulos from the HHI.
Aside from obvious benefits in being able to watch HD movies rather than talk to people around you, this technology could also have applications in places like hospitals. Radio frequency devices are not allowed, so this would be an alternative, and if lights in the surgical room are used as a transfer medium, this would make it possible to control wireless surgical robots or transmit x-ray images rapidly.
The fundamentals of visible light communication (VLC) were developed together with the industry partners Siemens and France Telecom Orange Labs.
"For VLC the sources of light – in this case, white-light LEDs – provide lighting for the room at the same time they transfer information. With the aid of a special component, the modulator, we turn the LEDs off and on in very rapid succession and transfer the information as ones and zeros," said Klaus-Dieter Langer. The modulation of the light is imperceptible to the human eye. A simple photo diode on the laptop acts as a receiver. "The diode catches the light, electronics decode the information and translate it into electrical impulses, meaning the language of the computer."
One advantage is that it takes only a few components to prepare the LEDs so that they function as transfer media. An obvious disadvantage currently is that as soon as something gets between the light and the photo diode, like if someone holds his hand over the diode, the transfer is impaired.
The scientists say VLC is not intended to replace regular Internet connections, it is best suited as an additional option for data transfer where radio transmission networks are not desired or possible. Combinations are also possible, such as optical WLAN in one direction and PowerLAN for the return channel. Films can be transferred to the PC like this and also played there, or they can be sent on to another computer.
Currently the scientists are developing their systems toward higher bit rates. "Using red-blue-green-white light LEDs, we were able to transmit 800 Mbit/s in the lab," said Klaus-Dieter Langer. "That is a world record for the VLC method."
The HHI scientists will showcase how videos are transmitted by light in Hall 11.1, Booth 8 at the International Telecommunications Fair IFA (Internationale Funkausstellung IFA) in Berlin from September 2-7, 2011.
