Wi-Fi, Bluetooth, and various radio-based technologies might be all the rage in current wireless technology, but researchers at Siemens are moving things up the spectrum a bit: they’ve just concluded new tests of wireless networking using visible light from white LEDs…and successfully transmitted data at rates of 500 Mbps over a distance of 5 meters. The tests were conducted in Berlin by Siemens in conjunction with the Heinrich Hertz Institute.
The technology works by varying the amount of visible light emitted by a white LED diode. The researchers used a white LED produced by Siemens subsidiary Osram that can have its power levels modulated at very high frequencies. The changed in the LED brightness are too fast to be perceived by the human eye, but an electronic photodetector doesn’t seem to have much trouble picking them out. Researchers were also able to demonstrate that combining five LEDs could extend the range of the technology at data rates up to 100 Mbps.
If the technology works out, it could herald a new range of applications for not only industry, but home and consumer wireless communication. Current wireless technologies used for Wi-Fi, cordless phones, and other solutions operate in very similar frequency spectrums, and are prone to packet loss and interference when the devices run into each other. Visible light networking, conversely, isn’t subject to interference from other forms of wireless communications: only a a properly positioned photoreceiver can pick up the visible light signal, and it doesn’t matter what other visible light signals are happening around it. Also, the visible light spectrum is (at present!) unregulated, meaning solutions providers wouldn’t have to apply for permitting and approval to deploy the technology. Of course, there’s always the downside that a visible light link can be severed by an intervening object—and it doesn’t cope well with things like walls and floors.
Siemens envisions applications not only in the home, but also in medical, manufacturing, and transportation applications: for instance, LED stoplights, signals, and signage could be used to send information to smart cars or trains.