Consumer-grade light-emitting diode (LED) bulbs can, with some modifications, be used for connecting devices such as appliances, wearable devices, sensors, toys and utilities that could comprise the Internet of Things (IoT), says a study."Interconnecting appliances, sensors and a wide variety of devices into the Internet of Things has many potential benefits but using radio links to do so threatens to make the radio spectrum an even scarcer resource," said Markus Gross from Disney Research lab at the Swiss Federal Institute of Technology Zurich (ETH)."Visible light communication networks conserve the radio spectrum, while also making it difficult to eavesdrop for anyone out of line of sight of the network," Gross added.By having individual LEDs alternate between sending modulated light signals and serving as receivers of signals, it is possible to create a network of bulbs that can send messages to each other and connect to devices, while having no discernible effect on room lighting.
Stefan Schmid from Disney Research in ETH Zurich implemented such a visible light communication (VLC) system, demonstrating that it is a viable way to interconnect devices within a room. The findings were presented recently at the IEEE International Conference on Sensing, Communication and Networking (SECON) 2016 in London."We used commercially available, off-the-shelf LED light bulbs as our starting point," Schmid said. "They are readily available at low cost and can be used in any lamp with standard sockets. This leads to an easy-to-setup and flexible testbed that can be readily duplicated," he added. The bulbs were modified, however. A "System-on-a-Chip" running an embedded version of Linux was added to each bulb, as well as photodiodes to enhance sensing of incoming signals and an additional power supply for the added electronics.The findings were presented recently at the IEEE International Conference on Sensing, Communication and Networking (SECON) 2016 in London.