Data Transfer with Light Instead of Radio Waves

For the first time, Siemens researchers have succeeded in transmitting up to 100 megabits of data per second (MBit/s) with visible light. In addition to the established WLAN technology, the scientists also want to use light for wireless data transfer. The factor driving this research forward is the ever-increasing demand for bandwidth and flexibility in gigabit home networks, which will be needed for future Internet services. Using high-performance, white light-emitting diodes (LEDs), the researchers from Corporate Technology in Munich succeeded in transmitting data across more than a meter of empty space.

Today’s home networks could become bottlenecks when fed by optical high-speed networks that use glass or polymer fibers, for instance, and provide transfer rates of 100 megabits per second or more for uploading and downloading data. These are the data speeds required for new Internet services such as high-definition TV and telemedicine applications.

Wireless home networks are also increasingly facing a different problem: in many buildings, the three independent WLAN frequency bands are multiply occupied, which leads to collisions among the data packets. In a situation like this, visible light, a previously unused medium in the public domain, offers a suitable alternative.

The transfer of data through empty space is accomplished with high-performance white LEDs with a number of notable features: they have a long operating life, are mechanically robust, run with a low operating voltage, and exhibit higher energy efficiency than normal lamps. The data is transferred simply through variation of the light emitted by the LED. The receiver is a photo detector that converts the signals back into electrical pulses.

Since January 2008 this subject has been the focal point of Omega, a European research project involving a consortium of 20 European partners from industry and the scientific community — including Siemens. The researchers are initially concentrating on increasing the data transfer with white LEDs. In late 2007, such technologies became the object of standardization activities, initiated and led by Samsung. This work is now proceeding in the framework of IEEE 802.15 (Institute of Electrical and Electronics Engineers), and plans call for a standard to be adopted at the end of 2010.