RFID is a localized solution relying on a closed system of access points (AP's) to set up boundaries for tracking. RFID is a good solution for buildings or outside areas where the APs are present(and the power to run those AP's is also available - Example, a construction yard full of equipment).

RFID reception and tracking depends upon a process of "lateration" (not to be confused with triangulation), the tag interacting (beaconing a signal) to the access points in order to calculate its position. RFID typically has an average accuracy of 10 meters +/-.

Because RFID reception is localized (with signal lower signal output needed), The beaconing (chirp rate) can be slowed to allow extended battery life - but then you lose granularity of motion and ability to measure speed rates.

RFID is not a workable solution for open sky GPS-type envorinments.

Accuracy is also dependent upon the way the AP's are set up and their population. 1.2 GHZ RFID is also prone to RFI.

If a tag goes beyond the AP boundaries, it is lost - cannot be tracked.

I know this because I was asked to do investigation into RFID a few years back, and also with a revisit this year - Nothing has changed in the operational arena, but advances have been made in Tag size (shrinking).

GPS takes up where RFID stops and delivers the same software tracking features.

Regards