Most devices and sensors connected to the Internet of Things (IoT) rely on the transmission of radio waves to communicate, which requires power, which means batteries if mains power is not a option. A Disney Research team is looking to exploit a technique called ultra-wideband (UWB) ambient backscatter, which would allow devices to overlay their communications on the multitude of FM and cellular signals already in the air.
“As we move toward connecting the next billion wireless devices to the Internet, using batteries to power those devices will become impractical,” said Markus Gross, vice president of Disney Research. “UWB ambient backscatter systems, which could potentially be deployed in any metropolitan area, have great potential to solve this dilemma.”
Ambient backscatter techniques essentially use the ubiquitous cloud of TV and cellular signals already in the air to power small transistors or to overlay data transmissions. This greatly reduces the power requirements of these sensors, potentially allowing them to communicate without transmitting their own radio waves.
Such technology has been tested many times over the past few years, from developing advertising posters that can piggyback on FM signals in the air and send advertisements to nearby devices, to powering small sensors without any external battery power.
The new innovation developed by the Disney Research Wireless Systems group allows a single device to backscatter a multitude of available ambient sources. Where earlier devices were calibrated to feed or piggyback on a single specific FM or cellular signal, this new UWB approach harnesses all broadcast signals in the 80 MHz to 900 MHz range, including digital TVs, FM radios and cellular networks, resulting in a stronger signal. -noise ratio and extension range.
The new system requires a single reader hub to receive and decode the sensor data carried on the backscatter signals, but realistically this would mean that a variety of backscatter-based sensors could easily be deployed in an office or a home environment that would communicate with a source-powered exchange.
The team was able to demonstrate node-to-reader communication over 22 m (72 ft) when using ambient signals from broadcast towers, and over 50 m (164 ft) with data rates up to at 1 kbps by simultaneously exploiting 17 sources of ambient signals.
Future prospects for this technology could allow inert, non-powered objects to be integrated with communicating sensors, such as a bus stop pole that contains live timetable information, a t-shirt that communicates on the heart rate to its wearer, or even a smartphone that could transmit text messages after its battery is depleted.