Global Sources
EE Times-Asia
Stay in touch with EE Times Asia
?
EE Times-Asia > RF/Microwave
?
?
RF/Microwave??

Battery-less communication device taps ambient wireless signals

Posted: 16 Aug 2013 ?? ?Print Version ?Bookmark and Share

Keywords:ambient backscatter? wireless signals? sensors?

Using a communication technique called 'ambient backscatter,' engineers from the University of Washington developed a system that enables two devices to interact without the need for battery power. The researchers built small devices with antennas that can detect available TV and cellular transmissions and reflect these existing signals to exchange information.

"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. "It's hopefully going to have applications in a number of areas including wearable computing, smart homes and self-sustaining sensor networks." The technology could enable a network of devices and sensors to communicate with no power source or human attention needed.

Two devices exchange information by reflecting or absorbing pre-existing radio signals

Figure 1: Two devices exchange information by reflecting or absorbing pre-existing radio signals.

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.

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.

A couch with sensors embedded sends a message to a user's phone using ambient backscatter

Figure 2: A couch with sensors embedded sends a message to a user's phone using ambient backscatter.

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.

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.





Article Comments - Battery-less communication device ta...
Comments:??
*? You can enter [0] more charecters.
*Verify code:
?
?
Webinars

Seminars

Visit Asia Webinars to learn about the latest in technology and get practical design tips.

?
?
Back to Top