Method of addressing messages and communications system

A method ol establishing wireless communications between an interrogator and individual ones ol multiple wireless identification devices, the method comprising utilizing a tree search method to attempt to identily individual ones ol the multiple wireless identification devices so as to be able to perform communications, without collision, between the interrogator and individual ones ol the multiple wireless identification devices, a search tree being defined for the tree search method, the tree having multiple nodes respectively representing subgroups ol the multiple wireless identification devices, wherein the interrogator transmits a command at a node, requesting that devices within the subgroup represented by the node respond, wherein the interrogator determines il a collision occurs in response to the command and, il not, repeats the command at the same node. An interrogator configured to transmit a command at a node, requesting that devices within the subgroup represented by the node respond, the interrogator further being configured to determine if a collision occurs in response to the command and, if not, to repeat the command at the same node.

38 Claims, 3 Drawing Sheets

RFID CIRCUITRY

POWER SOURCE

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