US Patent 8018336 System and method for RFID asset monitor

A system for an asset monitor includes a reader, a tag, and a router. The router actively transmits a location identification to the tag in a coverage area by using a radio frequency (RF). The tag is mounted on an article (or a user). The tag directly sends a signal to the reader or indirectly forwards to the reader via the router when the location identification of the tag is different from a current location identification or the location identification is repeatedly received up to a preset value. The sent signal includes a location identification and a current location identification that are received by the reader to determine the location of the article.