Internet @ speed of light

MUMBAI: German scientists created a method for computers & smartphones to transfer data at super high speeds using easily available LED lighting.

Regular LEDs can be turned into optical WLAN with only a few additional components thanks to visible light communication (VLC). The lights are then not just lighting up, they also transfer data. They send films in HD quality to your phone or laptop, with no loss in quality, quickly and safely.

Just imagine the following scenario: four people are comfortably in a room. Each one of them can watch a film from the Internet on his or her laptop, in HD quality. This is made possible thanks to optical networks. Light from the LEDs in the overhead lights serves as the transfer medium.

Sci-fi to reality
For a long time, this was just a vision for the future. However, scientists from the Fraunhofer Institute for Telecommunications and Heinrich Hertz Institute (HHI) in Berlin, Germany, have managed to developed this new transfer technology.

In May, the scientists demonstrated the results of their research. They 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 90 square feet. The receiver can be placed anywhere within this radius, which is currently the maximum range.

"This means that we transferred four videos in HD to four different laptops at the same time," says Anagnostis Paraskevopoulos from the HHI.

"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. The modulation of the light is imperceptible to the human eye. A simple photo diode on the laptop acts as a receiver.

As project manager Klaus-Dieter Langer explains, "The diode catches the light, electronics decode the info and translate it into electrical impulses , or the language of the computers."

One advantage is that it takes only a few components to prepare the LEDs so that they function as transfer media. One disadvantage is that as soon as something gets between the light and the photo diode (for example, when someone holds his hand over the diode) the transfer is impaired. Laptops, Palm devices or mobile telephones are all potential end devices.

Reaching where Wi-Fi can't 
The scientists emphasise that VLC is not intended to replace regular networks. It is best suited as an additional option for data transfer where radio transmission networks are not desired or not possible - without needing new cables or equipment in the house.

The new technology is suitable for hospitals, for example, because radio transmissions are not allowed there. Despite this fact, huge amounts of data must be transmitted and unzipped. If part of the communication would occur via the light in the surgical room, it would make it possible to control wireless surgical robots or transmit x-ray images.

In airplanes, each passenger could view his own program on a display, saving manufacturers miles of cables.

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," said Klaus-Dieter Langer. "That is a world record for the VLC method."