Internet of things (IoT) systems usually link networks of sensors via radio, but radios demand battery power thus limiting usability. Disney Research has determined that one solution may be to get rid of the radios all together and communicate via the ambient radio waves from TV, radio and cell phones. The Disney Researchers devised an ultra-low-power system of sensors that transmit data to a central receiver by reflecting the ambient radio waves from commercial broadcasting systems that already bathe most office environments. The researchers’ idea is to reuse all the radio signals that are around us as a medium for transmitting data, much like sending ripples across a pond.
This approach radically reduces the power requirements of the sensor nodes because it is the generation of radio waves that consumes most of their battery power. Backscatter communication already is used in passive RFID tags. In that case, an RFID reader transmits radiofrequency power to the battery-free RFID tag; the tag sends data to the reader by reflecting, or backscattering, the carrier wave back to the reader. These systems have limited range, which makes them impractical for IoT systems Other researchers have shown systems that require even less power by using ambient radio waves from a single source, such as a TV station. But, again, the range is limited to a few meters unless the power of the ambient signals is boosted to high levels. The Disney Researcher said the UWB approach – which backscatters all ambient sources – offers key advantages. Using multiple backscatter channels boosts the signal-to-noise ratio, substantially improving the sensitivity of the backscatter reader and decreasing dead zones. That, in turn, enables the system to operate on real-world ambient sources and substantially extends the range – to 22 meters when using ambient signals from broadcast towers and 50 meters when using ambient signals generated by mobile phone up-link traffic.