The Journal of the American Medical Association published a report on Wednesday that showed certain RFID systems may induce hazardous incidents in nearby critical care medical equipment.  The study examined the effects of a 128 kHz active RFID system and a 868 MHz passive RFID system on 41 different types of medical devices.  Out of 123 tests, 34 led to electromagnetic interference incidents, 22 of which were classified as hazardous, 2 as significant, and 10 as light.

Though many consider the result of this study to be a serious and shocking failure in engineering, some RFID vendors claim that the problem could be avoided by lowering the power output of the RFID readers.  In any case, this study highlights a key obstacle for pervasive RFID systems: it will probably not be possible to deploy RFID readers in all locations of interest due to a variety of issues including electromagnetic interference, budgetary issues, or aesthetic concerns.  As such, a successful RFID system will have to infer when a tag enters a location which is not covered by an RFID reader.  This is one of the challenges which we designed Cascadia, the RFID Ecosystem’s event detection middleware, to address.  In particular, Cascadia allows an admin to define a graph that describes locations of interest (which may or may not be covered by an RFID reader – see image below).  Cascadia then tracks tags over this graph and can infer with some probability when a tag enters a location that is not covered by an RFID reader.  See our MobiSys 2008 paper for details!