PL-Tags: Detecting Batteryless Tags Through the Power Lines in a Building

Shwetak Patel, Erich P. Stuntebeck, Thomas Robertson

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Abstract

We present a system, called PL-Tags, for detecting the presence of batteryless tags in a building or home through the power lines. The excitation (or interrogation) and detection of these tags occurs wirelessly entirely using the powerline infrastructure in a building. The PL-Tags proof-of-concept consists of a single plug-in module that monitors the power line for the presence of these tags when they are excited. A principal advantage of this approach is that it requires very little additional infrastructure to be added to a space, whereas current solutions like RFID require the deployment of readers and antennas for triggering tags. An additional benefit of PL-Tags is that the tags are wirelessly excited using an existing phenomenon over the power line, namely electrical transient pulses that result from the switching of electrical loads over the power line. We show how these energy rich transients, which occur by simply turning on a light switch, fan, television, etc. , excite these tags and how they are detected wirelessly over the power line. We contend that the PL-Tag system is another class of potential batteryfree approaches researchers can use for building pervasive computing applications that require minimal additional infrastructure.