Method of addressing messages and communications system
First Claim
1. 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.
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Accused Products
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.
178 Citations
38 Claims
- 1. 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.
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7. A method of addressing messages from an interrogator to a selected one or more of a number of communications devices, the method comprising:
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establishing a first predetermined number of bits to be used as unique identification numbers, and establishing for respective devices unique identification numbers respectively having the first predetermined number of bits; establishing a second predetermined number of bits to be used for random values; causing the devices to select random values, wherein respective devices choose random values independently of random values selected by the other devices; transmitting a command, from the interrogator, requesting devices having random values within a first specified group of random values to respond; receiving the command at multiple devices, devices receiving the command respectively determining if the random value chosen by the device falls within the first specified group and, if so, sending a reply to the interrogator; and determining using the interrogator if a collision occurred between devices that sent a reply and, if so, creating a second specified group smaller than the first specified group; and
, if not, again transmitting a command requesting devices having random values within the first specified group of random values to respond. - View Dependent Claims (8, 9, 10)
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11. A method of addressing messages from an interrogator to a selected one or more of a number of communications devices, the method comprising:
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establishing unique identification numbers for respective devices; causing the devices to select random values, wherein respective devices choose random values independently of random values selected by the other devices; transmitting an Identify command from the interrogator requesting devices having random values within a specified group of a plurality of possible groups of random values to respond, the plurality of possible groups being organized in a binary tree defined by a plurality of nodes at respective levels, the specified group being defined as being at one of the nodes, wherein the size of groups of random values decrease in size by half with each node descended; receiving the command at multiple devices, devices receiving the command respectively determining if the random value chosen by the device falls within the specified group and, if so, sending a reply to the interrogator; and
, if not, not sending a reply; anddetermining using the interrogator if a collision occurred between devices that sent a reply and, if so, creating a new, smaller, specified group by descending in the tree; and
, if not, transmitting an Identify at the same node. - View Dependent Claims (12, 13)
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14. A method of addressing messages from an interrogator to a selected one or more of a number of RFID devices, the method comprising:
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establishing for respective devices unique identification numbers respectively having a first predetermined number of bits; establishing a second predetermined number of bits to be used for random values; causing the devices to select random values, wherein respective devices choose random values independently of random values selected by the other devices; transmitting a command using the interrogator requesting devices having random values within a specified group of a plurality of possible groups of random values to respond, the specified group being equal to or less than the entire set of random values, the plurality of possible groups being organized in a binary tree defined by a plurality of nodes at respective levels, wherein the maximum size of groups of random values decrease in size by half with each node descended; receiving the command at multiple devices, devices receiving the command respectively determining if their chosen random values fall within the specified group and, only if so, sending a reply to the interrogator, wherein sending a reply to the interrogator comprises transmitting the unique identification number of the device sending the reply; determining using the interrogator if a collision occurred between devices that sent a reply and, if so, creating a new, smaller, specified group using a level of the tree different from the level used in the interrogator transmitting, the interrogator transmitting a command requesting devices having random values within the new specified group of random values to respond; and
, if not, the interrogator re-transmitting a command requesting devices having random values within the first mentioned specified group of random values to respond; andif a reply without collision is received from a device, the interrogator subsequently sending a command individually addressed to that device. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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- 21. A communications system comprising an interrogator, and a plurality of wireless identification devices configured to communicate with the interrogator in a wireless fashion, the interrogator being configured to employ tree searching 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, the interrogator being configured to follow a search tree, the tree having multiple nodes respectively representing subgroups of the multiple wireless identification devices, the interrogator being 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.
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27. A system comprising:
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an interrogator; a number of communications devices capable of wireless communications with the interrogator; means for establishing a first predetermined number of bits to be used as unique identification numbers, and for establishing for respective devices unique identification numbers respectively having the first predetermined number of bits; means for establishing a second predetermined number of bits to be used for random values; means for causing the devices to select random values, wherein respective devices choose random values independently of random values selected by the other devices; means for causing the interrogator to transmit a command requesting devices having random values within a specified group of random values to respond; means for causing devices receiving the command to determine if their chosen random values fall within the specified group and, if so, send a reply to the interrogator; and means for causing the interrogator to determine if a collision occurred between devices that sent a reply and, if so, create a new, smaller, specified group; and
, if not, transmit a command requesting devices having random values within the same specified group of random values to respond. - View Dependent Claims (28, 29, 30)
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31. A system comprising:
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an interrogator configured to communicate to a selected one or more of a number of communications devices; a plurality of communications devices; the devices being configured to select random values, wherein respective devices choose random values independently of random values selected by the other devices; the interrogator being configured to transmit a command requesting devices having random values within a specified group of a plurality of possible groups of random values to respond, the specified group being less than the entire set of random values, the plurality of possible groups being organized in a binary tree defined by a plurality of nodes at respective levels, the specified group being defined as being at one of the nodes, wherein the size of groups of random values decrease in size by half with each node descended; devices receiving the command being configured to respectively determine if their chosen random values fall within the specified group and, only if so, send a reply to the interrogator, wherein sending a reply to the interrogator comprises transmitting the unique identification number of the device sending the reply; the interrogator being configured to determine if a collision occurred between devices that sent a reply and, if so, create a new, smaller, specified group using a different level of the tree, the interrogator being configured to transmit a command requesting devices having random values within the new specified group of random values to respond; and
, if not, the interrogator being configured to re-transmit a command requesting devices having random values within the first mentioned specified group of random values to respond; andif a reply without collision is received from a device, the interrogator being configured to send a command individually addressed to that device. - View Dependent Claims (32, 33, 34)
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35. A system comprising:
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an interrogator configured to communicate to a selected one or more of a number of RFID devices; a plurality of RFID devices, respective devices being configured to store a unique identification number, respective devices being further configured to store a random value; the interrogator being configured to transmit an Identify command requesting devices having random values within a specified group of a plurality of possible groups of random values to respond, the plurality of possible groups being organized in a binary tree defined by a plurality of nodes at respective levels, the specified group being defined as being at one of the nodes, wherein the size of groups of random values decrease in size by half with each node descended; devices receiving the command respectively being configured to determine if their chosen random values fall within the specified group and, if so, send a reply to the interrogator; and
, if not, not send a reply; andthe interrogator being configured to determine if a collision occurred between devices that sent a reply and, if so, to create a new, smaller, specified group by descending in the tree; and
, if not, to transmit an Identify command at the same node. - View Dependent Claims (36, 37, 38)
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Specification