Patent ID: 7522049

Claim:
A presence detection system incorporated within a wireless local area network (WLAN), comprising: one or more WLAN access points each including a received signal strength measurement circuit and operating according to a revision of the IEEE 802.11 specification; an asset transmitter for transmitting a broadcast/multicast presence signal, wherein said presence signal is transmitted on one or more channels of said WLAN, to which no receiving unit in the WLAN can make a response and for which no association with another unit of said WLAN is required, and wherein said asset transmitter comprises a sniffer circuit for detecting other WLAN transmissions and wherein said asset transmitter transmits said presence signal only when said sniffer circuit detects that said other transmissions are absent; and an evaluator coupled to said one or more WLAN nodes for receiving signal strength values from each received signal strength measurement circuit within said one or more WLAN nodes and determining whether or not said asset transmitter is present in the vicinity of said one or more WLAN nodes in conformity with said signal strength values, whereby said presence signals can be detected by said access points without association of said asset transmitter with said WLAN while maintaining normal operation with other associated units of said WLAN.