Method of addressing messages and communications systems
First Claim
1. A method of establishing wireless communications between an interrogator and individual ones of multiple wireless identification devices, the wireless identification devices having respective identification numbers and being addressable by specifying identification numbers with any one of multiple possible degrees of precision, the method comprising utilizing a tree search in an arbitration scheme to determine a degree of precision necessary to establish one-on-one communications 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 selectable levels respectively representing subgroups of the multiple wireless identification devices, the level at which a tree search starts being variable the method further comprising starting the tree search at any selectable level of the search tree.
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Abstract
A method of and apparatus for establishing wireless communications between an interrogator and individual ones of multiple wireless identification devices, the method comprising utilizing a tree search method to establish 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 levels respectively representing subgroups of the multiple wireless identification devices, the method further comprising starting the tree search at a selectable level of the search tree. A communications system comprising an interrogator, and a plurality of wireless identification devices configured to communicate with the interrogator in a wireless fashion, the respective wireless identification devices having a unique identification number, the interrogator being configured to employ a tree search technique to determine the unique identification numbers of the different wireless identification devices so as to be able to establish communications between the interrogator and individual ones of the multiple wireless identification devices without collision by multiple wireless identification devices attempting to respond to the interrogator at the same time, wherein the interrogator is configured to start the tree search at a selectable level of the search tree. In one embodiment, the interrogator transmits a first request indicating a subgroup of random numbers out of a total number of possible random numbers. The wireless identification devices each determine if the random number generated by each wireless identification device falls within the subgroup, and if so, the wireless identification device responds to the interrogator. If a collision between wireless identification device responses is detected by the interrogator, the interrogator transmits a second request indicating a subgroup of random numbers.
119 Citations
83 Claims
- 1. A method of establishing wireless communications between an interrogator and individual ones of multiple wireless identification devices, the wireless identification devices having respective identification numbers and being addressable by specifying identification numbers with any one of multiple possible degrees of precision, the method comprising utilizing a tree search in an arbitration scheme to determine a degree of precision necessary to establish one-on-one communications 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 selectable levels respectively representing subgroups of the multiple wireless identification devices, the level at which a tree search starts being variable the method further comprising starting the tree search at any selectable level of the search tree.
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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 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; determining the maximum number of devices potentially capable of responding to the interrogator; transmitting a command from the interrogator requesting devices having random values within a specified group of random values to respond, by using a subset of the second predetermined number of bits, the specified group being chosen in response to the determined maximum number; 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 determining using the interrogator if a collision occurred between devices that sent a reply and, if so, creating a new, smaller, specified group. - View Dependent Claims (8, 9, 10, 11)
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12. 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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causing the devices to select random values for use as arbitration numbers, wherein respective devices choose random values independently of random values selected by the other devices, the devices being addressable by specifying arbitration numbers with any one of multiple possible degrees of precision; transmitting a 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 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, wherein the size of groups of random values decrease in size by half with each node descended, wherein the specified group is below a node on the tree selected based on the maximum number of devices capable of communicating with the interrogator; 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. - View Dependent Claims (13, 14, 15)
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16. 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 a predetermined number of bits to be used for random values, the predetermined number being a multiple of sixteen; 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 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, wherein the specified group is below a node on a level of the tree selected based on the maximum number of devices known to be capable of communicating with the interrogator; 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, only if so, sending a reply to the interrogator, wherein sending a reply to the interrogator comprises transmitting both the random value of the device sending the reply and the unique identification number of the device sending the reply; using the interrogator to determine 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 a reply without collision is received from a device, the interrogator subsequently sending a command individually addressed to that device. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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- 24. A communications system comprising an interrogator, and a plurality of wireless identification devices configured to communicate with the interrogator in a wireless fashion, the wireless identification devices having respective identification numbers, the interrogator being configured to employ a tree search in a search tree having multiple selectable levels, to determine the identification numbers of the different wireless identification devices with sufficient precision so as to be able to establish one-on-one communications between the interrogator and individual ones of the multiple wireless identification devices, wherein the interrogator is configured to start the tree search at any selectable level of the search tree.
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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 predetermined number of bits to be used as random numbers, and for causing respective devices to select random numbers respectively having the predetermined number of bits; means for inputting a predetermined number indicative of the maximum number of devices possibly capable of communicating with the receiver; means for causing the interrogator to transmit a command requesting devices having random values within a specified group of random values to respond, the specified group being chosen in response to the inputted predetermined number; 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. - View Dependent Claims (28, 29)
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30. 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, different sized groups of devices being addressable by specifying random values with differing levels of precision; 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, wherein the size of groups of random values decrease in size by half with each node descended, wherein the specified group is below a node on the tree selected based on a predetermined maximum number of devices capable of communicating with the interrogator; devices receiving the command being configured to respectively 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, create a new, smaller, specified group by descending in the tree. - View Dependent Claims (31, 32, 33)
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34. 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 unique identification numbers respectively having a first predetermined number of bits, respective devices being further configured to store a second predetermined number of bits to be used for random values, respective devices being configured to select random values independently of random values selected by the other devices; the interrogator being configured to transmit an identify command requesting a response from devices having random values within a specified group of a plurality of possible groups or random values, the specified group being less than or equal to 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, wherein the specified group is below a node on a level of the tree selected based on the maximum number of devices known to be capable of communicating with the interrogator; devices receiving the command respectively being configured to 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 both the random value of the device sending the reply and 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 level of the tree different from the level used in previously transmitting an identify command, the interrogator transmitting an identify command requesting devices having random values within the new specified group of random values to respond; and the interrogator being configured to send a command individually addressed to a device after communicating with a device without a collision. - View Dependent Claims (35, 36, 37)
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38. A method, comprising:
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transmitting, from a reader, an initial wireless command to start identification of a plurality of radio frequency identification (RFID) tags, the initial wireless command specifying at least two bits and requesting first RFID tags having the at least two bits to reply with at least random numbers generated on the first RFID tags as identifiers to be used by the reader in subsequent communications to individually address the first RFID tags; determining whether there is a collision in response to the initial wireless command;
identifying, from a response to the initial command, a random number generated at an RFID tag, if there is no collision in response to the initial wireless command; andtransmitting, from the reader, a subsequent wireless command to identify RFID tags, the subsequent command specifying at least the two bits to request replies. - View Dependent Claims (39, 40, 41, 42, 43, 44)
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45. A radio frequency identification (RFID) interrogator, comprising:
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one or more antennas; a controller; a transmitter coupled to the controller and the one or more antennas to send a first wireless radio frequency (RF) signal to start identification of individual tags of a population of RFID tags, the first RF signal requesting RFID tags having first bits specified in the first RF signal to reply, the first bits having at least two bits; and a receiver coupled to the controller and the one or more antennas to detect a collision in response to the first RF signal and, when there is no collision in response to the first RF signal, to determine an identifier of a first RFID tag from a reply to the first RF signal; wherein the transmitter is to subsequently use the identifier, determined from the reply to the first RF signal, to address the first RFID tag, among the population of RFID tags, for a response from the first RFID tag. - View Dependent Claims (46, 47, 48, 49)
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50. A radio frequency identification (RFID) system, comprising:
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a plurality of RFID tags; and an interrogator having a range for wireless communications, the plurality of RFID tags disposed within the range for communications with the interrogator, the interrogator comprising; at least one antenna, a transmitter coupled to the at least one antenna to transmit a first wireless radio frequency (RF) signal to initiate a search to identify the RFID tags, the first RF signal specifying at least two bits, wherein RFID tags having the at least two bits reply to the first RF signal with at least random numbers generated on respective RFID tags, and a receiver coupled to the at least one antenna to identify, from at least one reply to the first RF signal, a random number generated by a first RFID tag, if there is no response collision in replying to the first RF signal; wherein the transmitter is to subsequently use the random number, identified from the reply to the first RF signal, to request a response from the first RFID tag. - View Dependent Claims (51, 52, 53, 54, 55, 56)
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57. A radio frequency identification (RFID) system, comprising:
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an interrogator to transmit an initial wireless radio frequency (RF) signal to start a search to identify RFID tags, the initial wireless RF signal specifying at least two first bits and requesting replies; and a set of RFID tags, each tag of the set having; an antenna, a memory storing a plurality of bits; and a circuit coupled to the antenna to receive the initial RF signal, to compare the at least two first bits with corresponding bits stored in the memory, to independently generate a random number as an identifier, to generate a random value to select a time slot to reply, and to reply with the random number in accordance with the time slot, if there is a match between the at least two first bits specified in the initial RF signal and the corresponding bits stored in the memory; wherein the interrogator is to individually address a first RFID tag among the set of RFID tags, using the random number of the first RFID tag identified from a reply to the first wireless RF signal, to request a response from the first RFID tag. - View Dependent Claims (58, 59, 60, 61, 62)
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63. A radio frequency identification (RFID) method, comprising:
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transmitting, from a reader, a first wireless command to initiate identification of a population of RFID tags and a plurality of subsequent wireless commands to continue the identification of a population of RFID tags, the first command including first bits, the first command to request a set of RFID tags having the first bits to reply with identifiers of the set of RFID tags, the identifiers including random numbers individually generated by the set of RFID tags, the first bits including at least two bits; generating, by the set of RFID tags, the random numbers independent from each other; generating, by the set of RFID tags, random values; replying, by the set of RFID tags, to the first command and the subsequent command with at least the random numbers of the set of RFID tags, in an order in accordance with the random values; receiving, at the reader, a reply to the first command from a first RFID tag; determining whether there is a collision in replying to the first command; if there is no collision in replying to the first command, identifying from the reply a random number generated by the first RFID tag; and transmitting a second wireless command to address the first RFID tag using the random number, the second wireless command to request a response from the first RFID tag addressed by the random number. - View Dependent Claims (64, 65, 66, 67, 68, 69, 70, 71, 72)
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73. A radio frequency communications-based method of conducting a financial transaction, comprising:
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sending a first wireless radio frequency (RF) signal to start identification of one or more radio frequency devices of a population of radio frequency devices, the first RF signal requesting one or more radio frequency devices having at least two first bits specified in the first RF signal to reply; receiving a response via a receiver coupled to a controller and one or more antennas, said receiver, said controller and said one or more antennas configured to detect a collision in response to the first RF signal and, when there is no collision in response to the first RF signal, to determine an identifier of a first radio frequency device from a reply to the first RF signal; addressing the first radio frequency device using the identifier determined from the reply to the first RF signal so as to elicit a subsequent response from the first radio frequency device; and initiating a financial transaction based at least in part on said acts of sending, receiving and addressing, thereby resulting in the debiting of an account associated with said first radio frequency device. - View Dependent Claims (74, 75, 76, 77, 78, 79, 80, 81, 82, 83)
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Specification