AmbientBackscatterWirelessCommunicationOutofThinAir.PDFVIP

Ambient Backscatter: Wireless Communication Out of Thin Air Vincent Liu, Aaron Parks, Vamsi Talla, Shyamnath Gollakota, David Wetherall, Joshua R. Smith University of Washington {liuv, anparks, vamsit, gshyam, djw, jrsjrs}@ ABSTRACT We present the design of a communication system that enables two devices to communicate using ambient RF as the only source of power. Our approach leverages existing TV and cellular trans- missions to eliminate the need for wires and batteries, thus enabling ubiquitous communication where devices can communicate among themselves at unprecedented scales and in locations that were pre- viously inaccessible. To achieve this, we introduce ambient backscatter, a new com- munication primitive where devices communicate by backscatter- ing ambient RF signals. Our design avoids the expensive process of generating radio waves; backscatter communication is orders of magnitude more power-efficient than traditional radio communica- tion. Further, since it leverages the ambient RF signals that are al- Figure 1—Ambient Backscatter: Communication between two ready around us, it does not require a dedicated power infrastruc- battery-free devices. One such device, Alice, can backscatter am- ture as in traditional backscatter communication. To show the fea- bient signals that can be decoded by other ambient backscatter de- sibility of our design, we prototype ambient backscatter devices in vices. To legacy receivers, this signal is simply an additional source of multi-path, and they can still decode the original transmission. hardware and achieve information rates of 1 kbps over distances of 2.5 feet and 1.5 feet, while operating outdoors and indoors re-