Engineers at the University of Washington have successfully demonstrated a short-range wireless communications system that is not only battery-free but also makes use of ambient radio waves as the carrier channel. The project paves the way for the creation of peer to peer networks that can be created out of ‘thin air’.
In the video demonstration below the researchers used two credit card sized devices, neither of which is equipped with a battery, to communicate with each other. The system works with each device either absorbing or reflecting the ambient radio waves that are all around us, coming from TV broadcast towers, cellular towers, wifi access points and the like, giving rise to the name ‘ambient backscatter’.
Absorption and reflection of the RF waves gives a device two states, which can be interpreted in a binary fashion, allowing one device to communicate with another at distances of 1.5 feet indoors and 2.5 feet outdoors, while being as far away as 6.5 miles from the RF backscatter source.
Data transfer speeds are only in the range of 1Kbps but that is enough for simple applications like sensors or similar use cases to RFID. Theoretically, it could even allow a device to send a text message even when the battery is depleted, although there are some issues here with regards to powering the screen.
“What we are doing is transforming ambient RF signals into a source of power and a communication medium,” the researchers said.