Method of addressing messages and communications
First Claim
1. A method of establishing wireless communications between an interrogator and wireless identification devices, the method comprising utilizing a tree search technique to establish communications, without collision, between the interrogator and individual ones of the multiple wireless identification devices, the method including using a search tree having multiple nodes respectively representing subgroups of the multiple wireless identification devices, the method further comprising, for a node, transmitting a command, using the interrogator, requesting that devices within the subgroup represented by the node respond, determining with the interrogator if a collision occurred in response to the command and, if not, repeating 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 . 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.
135 Citations
85 Claims
- 1. A method of establishing wireless communications between an interrogator and wireless identification devices, the method comprising utilizing a tree search technique to establish communications, without collision, between the interrogator and individual ones of the multiple wireless identification devices, the method including using a search tree having multiple nodes respectively representing subgroups of the multiple wireless identification devices, the method further comprising, for a node, transmitting a command, using the interrogator, requesting that devices within the subgroup represented by the node respond, determining with the interrogator if a collision occurred in response to the command and, if not, repeating 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 for respective devices unique identification numbers;
causing the devices to select random values, wherein respective devices choose random values independently of random values selected by the other devices;
transmitting a communication, from the interrogator, requesting devices having random values within a first specified group of random values to respond;
receiving the communication at multiple devices, devices receiving the communication 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 communication 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 a transponder 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 a communication from the transponder 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;
receiving the communication at multiple devices, devices receiving the communication respectively determining if the random value chosen by the device falls within the specified group and, if so, sending a reply to the transponder; and
, if not, not sending a reply; and
determining using the transponder 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 a communication 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;
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;
receiving the command at multiple RFID devices, RFID 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 different level of the tree, 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; and
if 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 using RF, 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 for respective devices unique identification numbers respectively having the first predetermined number of bits;
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, to 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, to 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; and
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;
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. - 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 a 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;
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; and
the 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 a command at the same node. - View Dependent Claims (36, 37, 38)
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39. A radio frequency identification (RFID) system, comprising:
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a plurality of RFID tags; and
at least one interrogator, the interrogator to transmit a first request to the plurality of RFID tags, the first request specifying a first subgroup of a group of random numbers, among the plurality of RFID tags at least one RFID tag having generated a random number that is within the first subgroup to provide a first response, the interrogator to receive one or more responses, including the first response, from one or more of the plurality of RFID tags respectively, and the interrogator to repeat the first request if the first response is received without a detected collision. - View Dependent Claims (40, 41, 42, 43, 44)
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45. A method implemented in a radio frequency identification (RFID) system having at least one RFID tag and at least one RFID interrogator, the method comprising:
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generating random numbers at a plurality of RFID tags, including an RFID tag affixed to an object;
transmitting a first command from the interrogator to select RFID tags, including the RFID tag affixed to the object, that have generated random numbers that are within a subset of random numbers;
the selected RFID tags transmitting a response, including a random number generated by the RFID tag affixed to the object;
if the random number is received at the interrogator, retransmitting the first command. - View Dependent Claims (46, 47, 48)
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49. An interrogator, comprising:
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one or more antennas to poll a plurality of radio frequency identification (RFID) tags;
means for transmitting a first command to select a first subset of the plurality of RFID tags;
means for receiving one or more responses from the subset of RFID tags, the one or more responses including a random number generated at a first RFID tag of the plurality of RFID tags;
means for transmitting the first command if at least one of the one or more responses is received without a collision; and
means for transmitting a second command to select a second subset of the plurality of RFID tags if a collision is detected in the one or more responses. - View Dependent Claims (50, 51)
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52. A method implemented in a radio frequency identification (RFID) device, the method comprising:
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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, retransmitting the response when the first command is subsequently repeated. - View Dependent Claims (53)
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54. A method implemented in a radio frequency identification (RFID) system having an interrogator to poll a plurality of RFID tags, the method comprising:
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transmitting a first command to select a first subset of RFID tags;
receiving one or more responses from the subset of RFID tags, the one or more responses including a random number generated at a first RFID tag of the plurality of RFID tags; and
retransmitting the first command if at least one of the one or more responses is received without a collision. - View Dependent Claims (55, 56, 57, 58)
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59. A radio frequency identification (RFID) device, comprising:
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an antenna;
a receiver coupled to the antenna to receive a first command from an interrogator, the first command comprising a first value having multiple bits to select a group of one or more RFID devices in a field of the interrogator;
processing circuitry to determine if the RFID device is selected by the interrogator based on the first value; and
a transmitter to communicate a response to the first command in a first time slot with a first probability if the RFID device is selected by the interrogator in accordance with the first value, wherein the response includes an identifier of the RFID device and the first probability is indicated by the first command;
wherein if the first command, including the first value to select the group, is subsequently repeated by the interrogator while the RFID device remains within the field of the interrogator, the RFID device is configured to;
remain silent, if the response was received at the interrogator without detecting a collision, and retransmit the response if the response was not received at the interrogator without detecting a collision. - View Dependent Claims (60, 61, 62, 63, 64, 65)
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66. A radio frequency identification (RFID) interrogator, comprising:
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an antenna;
a transmitter coupled to the antenna to transmit a first command comprising a value, having multiple bits, corresponding to a group of one or more RFID devices to be selected in a field of the interrogator;
a receiver to receive a response to the first command from an RFID device selected by the first command in accordance with the value, the response to include an identifier of the RFID device and to be received in a time slot in accordance with a time slot method; and
processing circuitry to determine if the response is received without a collision, and if so, to transmit a second command to silence the RFID device and to retransmit the first command, including the value, to reselect the group to respond to the first command. - View Dependent Claims (67, 68, 69, 70, 71)
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72. A method comprising:
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transmitting from an interrogator a first command, including a first identifier comprising a plurality of bits, to select a set of one or more RFID devices, corresponding to the first identifier, in a field of the interrogator, and to request the set to respond in accordance with a time slot method in which an RFID device responds in a first time slot with a probability indicated by the first command;
receiving a first response to the first command from a first RFID device of the set, wherein the first response is received in a time slot in accordance with the time slot method and the first response includes a second identifier of the RFID device;
detecting no collision in the first response from the first RFID device; and
retransmitting from the interrogator the first command, including the first identifier, to select the set of one or more RFID devices and to request the set to respond while the set remains in the field of the interrogator. - View Dependent Claims (73, 74, 75, 76, 77, 78)
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79. A radio frequency identification (RFID) system, comprising:
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an interrogator to transmit a first command to select a group of one or more RFID devices in a field of the interrogator, wherein the first command includes a first identifier, comprising a plurality of bits, that corresponds to the group of one or more RFID devices; and
an RFID device in the field of the interrogator to determine, using the first identifier, if the RFID device is selected as one of the group, and if so, to communicate a response to the first command in a first time slot with a first probability, wherein the response includes a second identifier of the RFID device;
wherein the interrogator is to retransmit the first command, including the first identifier, after the interrogator receives the response, without a collision, from the RFID device and while the group remains in the field of the interrogator. - View Dependent Claims (80, 81, 82, 83, 84, 85)
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Specification