Wireless identification systems and protocols

Abstract

Monitoring systems and protocols are disclosed that are flexible in mode operation and format depending on the environment in which they are used. Such monitoring systems and protocols are able to change their utilization automatically, or by received instruction to do so. A location detection system includes one or more low frequency transmitters, one or more radio frequency monitoring tags and one or more receiving devices. The low frequency transmitter transmits location identification information, such as the transmitter ID, to a tag in the vicinity of the transmission. The tag relays the transmitter ID using a higher frequency transmission sent from the tag to the receiver. Communication protocols are disclosed that enable deciphering of multiple tag transmissions starting simultaneously.

1 . In a system for monitoring location of tags, a method performed by a tag for transmitting a tag message, the method comprising: 
 determing whether the tag has been moved since an immediately prior tag message transmission; and    if it is determined that the tag has been moved, then beginning transmitting the tag message without awaiting lapse of an intermessage gap; otherwise, beginning transmitting the tag message after lapse of the intermessage gap.