Evan Welbourne Karl Koscher Emad Soroush Magdalena Balazinska Gaetano Borriello Longitudinal study of a building-scale RFID ecosystem. 69-82 2009 MobiSys http://doi.acm.org/10.1145/1555816.1555824 conf/mobisys/2009 db/conf/mobisys/mobisys2009.html#WelbourneKSBB09