Tuesday, August 13, 2013

SIGCOMM2013: Dude, Where’s My Card? RFID Positioning That Works with Multipath and Non-Line of Sight

Jue Wang and Dina Katabi

Goal: Locate RFID to within 10 to 15cm

Challenge: multipath effect
Previous methods like Angle-of-Arrival (AoA) and RSSI are not accurate when influenced by multipath effect.

Proposed method: PinIt
An accurate RFID localization even in multipath and non-line-of-sight environment

How does PinIt exploit multipath?
Because signals from nearby RFIDs propagate along closer paths and experience similar reflection, we can construct multipath profile for each RFID.

How to obtain multipath profiles?
We can capture multipath profiles with antennas array, but it is impractical to have so many antennas on a device. Thus, we capture multipath profiles with a sliding antenna.

How to detect proximity from multipath profiles?
A naive solution is to correlate profiles. However, correlation cannot capture peak shift, which is the usual case in similar multipath profiles. We borrow a well-established technique from speech processing, Dynamic Time Warping, to cope with the problem.

Conclusion:
PinIt improve accuracy compared to AoA and RSSI.
PinIt enables new applications.