News
and Information
We might be one step
closer to an Internet-of-things reality.
University of
Washington engineers have created a new wireless communication system that
allows devices to interact with each other without relying on batteries or
wires for power.
University of Washington
Using ambient
backscatter, these devices can interact with users and communicate with each
other without using batteries. They exchange information by reflecting or
absorbing pre-existing radio signals.
The new communication
technique, which the researchers call “ambient
backscatter,” takes advantage of
the TV and cellular transmissions that already surround us around the clock.
Two devices communicate with each other by reflecting the existing signals to
exchange information. The researchers built small, battery-free devices with
antennas that can detect, harness and reflect a TV signal, which then is picked
up by other similar devices.
The technology could
enable a network of devices and sensors to communicate with no power source or
human attention needed.
“We can repurpose
wireless signals that are already around us into both a source of power and a
communication medium,” said lead researcher Shyam Gollakota, a UW assistant professor of computer
science and engineering. “It’s hopefully going to have applications in a number
of areas including wearable computing, smart homes and self-sustaining sensor
networks.”
The researchers
published their results at the Association for Computing Machinery’sSpecial Interest Group
on Data Communication 2013 conference in Hong Kong, which began Aug. 13. They have received the conference’s
best-paper award for their research.
“Our devices form a
network out of thin air,” said co-author Joshua
Smith, a UW associate
professor of computer science and engineering and of electrical engineering.
“You can reflect these signals slightly to create a Morse code of communication
between battery-free devices.”
University of Washington
Everyday objects could
be enabled with battery-free tags to communicate with each other. A couch could
use ambient backscatter to let the user know where his keys were left.
Smart sensors could be
built and placed permanently inside nearly any structure, then set to
communicate with each other. For example, sensors placed in a bridge could
monitor the health of the concrete and steel, then send an alert if one of the
sensors picks up a hairline crack. The technology can also be used for
communication – text messages and emails, for example – in wearable devices,
without requiring battery consumption.
The researchers tested
the ambient backscatter technique with credit card-sized prototype devices
placed within several feet of each other. For each device the researchers built
antennas into ordinary circuit boards that flash an LED light when receiving a
communication signal from another device.
Groups of the devices
were tested in a variety of settings in the Seattle area, including inside an
apartment building, on a street corner and on the top level of a parking
garage. These locations ranged from less than half a mile away from a TV tower
to about 6.5 miles away.
University of Washington
Researchers
demonstrate how one payment card can transfer funds to another card by
leveraging the existing wireless signals around them. Ambient RF signals are
both the power source and the communication medium.
They found that the
devices were able to communicate with each other, even the ones farthest from a
TV tower. The receiving devices picked up a signal from their transmitting
counterparts at a rate of 1 kilobit per second when up to 2.5 feet apart
outdoors and 1.5 feet apart indoors. This is enough to send information such as
a sensor reading, text messages and contact information.
It’s also feasible to
build this technology into devices that do rely on batteries, such as
smartphones. It could be configured so that when the battery dies, the phone
could still send text messages by leveraging power from an ambient TV signal.
The applications are
endless, the researchers say, and they plan to continue advancing the capacity
and range of the ambient backscatter communication network.
The other researchers
involved are David Wetherall, a UW professor of computer science and engineering, Vincent
Liu, a doctoral student
in computer science and engineering, andAaron
Parks and Vamsi Talla, both doctoral students in electrical engineering.
The research was
funded by the University of Washington through a Google Faculty Research Award
and by the National Science Foundation’s Research Center for Sensorimotor
Neural Engineering at the UW.
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