Importance

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Abstract

A method of establishing wireless communications between an interrogator and individual ones of multiple wireless identification devices.[., the method comprising utilizing a tree search method to attempt to identify individual ones of the multiple wireless identification devices so as to be able to perform communications, without collision, between the interrogator and individual ones of the multiple wireless identification devices, a search tree being defined for the tree search method, the tree having multiple nodes respectively representing subgroups of 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 if a collision occurs in response to the command and, if 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.]. . .Iadd.In one aspect, a method implemented in an RFID device includes: receiving a first command, comprising a first set of bit values, from an interrogator to select the RFID device based on a comparison between the first set of bit values and data stored in the RFID device; transmitting a response to the first command, the response including an identifier of the RFID device; if the response is received at an interrogator, remaining silent when the first command is subsequently repeated; and if the response is not received at the interrogator, re-transmitting the response when the first command is subsequently repeated..Iaddend.

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First Claim