Communication methods using slotted replies
First Claim
Patent Images
1. A method comprising the steps of:
- sending a first signal from an interrogator to a plurality of radio frequency identification (RFID) tags, the first signal including parameters that describe bit storage locations of memory and a bit string;
each of the plurality of tags receiving the first signal and comparing the bit string against respective bits stored in the bit storage locations of memory of each respective tag to determine if the respective tag is a member of a selected tag group;
each tag of the selected tag group independently picking a respective first random slot value from a first number of slot values in accordance with an arbitration scheme; and
a first tag of the selected tag group backscattering a first reply to the interrogator, the first reply including a first random number independently generated by the first tag, the first tag replying in accordance with a first sequence determined at least in part by the respective first random slot value independently picked by each tag of the selected tag group.
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Abstract
An RFID tag population is selected by an interrogator. Each tag of the selected tag population then responds to the interrogator in accordance with a slotted arbitration scheme. According to the slotted arbitration scheme, each tag of the selected tag population picks its own random value from a range of integers indicated by the interrogator. The random value corresponds to a slot. The interrogator may indicate that the range of integers is to be adjusted. Each tag of the selected tag population responds to the interrogator with a random number.
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Citations
78 Claims
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1. A method comprising the steps of:
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sending a first signal from an interrogator to a plurality of radio frequency identification (RFID) tags, the first signal including parameters that describe bit storage locations of memory and a bit string; each of the plurality of tags receiving the first signal and comparing the bit string against respective bits stored in the bit storage locations of memory of each respective tag to determine if the respective tag is a member of a selected tag group; each tag of the selected tag group independently picking a respective first random slot value from a first number of slot values in accordance with an arbitration scheme; and a first tag of the selected tag group backscattering a first reply to the interrogator, the first reply including a first random number independently generated by the first tag, the first tag replying in accordance with a first sequence determined at least in part by the respective first random slot value independently picked by each tag of the selected tag group. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method comprising the steps of:
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sending a first signal from an interrogator to a plurality of radio frequency identification (RFID) tags to select a tag group, the first signal including a set of parameters that describe bit storage locations of memory and a bit string; each of the plurality of tags receiving the first signal and comparing the bit string to a respective number contained in the respective bit storage locations of memory within each of the plurality of tags to determine if a respective tag is a member of the tag group; sending a second signal from the interrogator; each tag of the tag group picking a respective first random slot value from a first number of slot values in response to the second signal, a first sequence in which tags of the tag group are to reply to the interrogator being determined at least in part by the first random slot values associated with the tag group; a first tag of the tag group backscattering a first reply to the interrogator, the first reply including a first random number generated by the first tag, the first tag replying in accordance with the first sequence; the interrogator receiving the first reply from the first tag, and, in response thereto, the interrogator sending an acknowledge signal to acknowledge the first tag; sending a third signal from the interrogator; and a second tag of the tag group backscattering a second reply to the interrogator in response to the third signal, the second reply including a second random number generated by the second tag, the second tag replying in accordance with the first sequence. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method comprising the steps of:
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sending a query command from an interrogator to a plurality of wireless identification devices, the query command including a first set of fields comprising first bit values; each device of the plurality of devices using the first bit values to determine if the respective device belongs to a group of chosen wireless identification devices that may respond to the query command; each device of the group of chosen devices picking a respective first random slot value from a first number of slot values in response to the query command, the first number of slot values being determined using the first bit values; a first device of the group of chosen devices backscattering a first random number during a first time, the first random number generated by the first device; sending a subsequent command from the interrogator to the group of chosen devices, the subsequent command including a second set of fields comprising second bit values; each device of at least a portion of the group of chosen devices picking a respective second random slot value from a second number of slot values in response to the subsequent command, the second number of slot values varying from the first number of slot values and determined using the second bit values; and a second device of the at least a portion of the group of chosen devices backscattering a second random number during a second time, the second random number generated by the second device. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29)
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30. A method comprising:
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sending a first signal from an interrogator to first and second radio frequency identification (RFID) tags, the first signal including a bit string and indicating bit storage locations of memory, the first tag having stored therein a first set of bits in bit storage locations corresponding to the bit storage locations of memory, and the second tag having stored therein a second set of bits in bit storage locations corresponding to the bit storage locations of memory; the first tag receiving the first signal and comparing the bit string against the first set of bits to determine that the first tag is selected; the second tag receiving the first signal and comparing the bit string against the second set of bits to determine that the second tag is selected; sending a query command from the interrogator, the query command including a set of fields to select the first and second tags for response to the query command; the first tag picking a first random slot value from a first number of slot values in response to the query command in accordance with an arbitration scheme; the second tag picking a second random slot value from the first number of slot values in response to the query command in accordance with the arbitration scheme; the first tag backscattering a first reply to the interrogator during a first period of time, the first reply including a first random number generated by the first tag; and the second tag backscattering a second reply to the interrogator during a second period of time, the second reply including a second random number generated by the second tag. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37)
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38. A method comprising the steps of:
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sending a first command from an interrogator to a radio frequency identification (RFID) tag, the first command including a bit string and indicating bit storage locations of memory, the tag having stored therein an identifier, a portion of the identifier being stored in a location that corresponds to the bit storage locations of memory indicated by the first command; the tag comparing the bit string against the portion of the identifier to determine if the tag is selected; sending a second command from the interrogator; the tag picking a first random value from a first range of values in response to the second command, the first range of values corresponding to slots in accordance with an arbitration scheme; the tag backscattering a first self-generated random number during a slot of time that corresponds to the first random value in accordance with the arbitration scheme; the interrogator detecting a collision upon receiving the first random number; sending a third command from the interrogator; the tag picking a second random value from a second range of values different from the first range of values in response to the third command, the second range of values corresponding to slots in accordance with the arbitration scheme; and the tag backscattering a second self-generated random number during a slot of time that corresponds to the second random value in accordance with the arbitration scheme. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. A method comprising:
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sending a first command from an interrogator, the first command including a first set of parameters; a first radio frequency identification (RFID) device wirelessly receiving the first command and using the first set of parameters to determine if the first device is a participant that may respond to the first command and also to determine a first number of slots, the first device randomly picking a first slot from the first number of slots; a second RFID device wirelessly receiving the first command and using the first set of parameters to determine if the second device is a participant that may respond to the first command and also to determine the first number of slots, the second device randomly picking a second slot from the first number of slots; and the first device backscattering a first 16 bit random number during a period of time corresponding to the first slot randomly picked by the first device, the first random number generated by the first device. - View Dependent Claims (54, 55, 56, 57, 58, 59)
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60. A method comprising:
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sending a first query command from an interrogator to a radio frequency identification (RFID) tag, the first query command including a first set of fields; the tag wirelessy receiving the first query command; the tag determining, based on at least one field of the first set of fields, if the tag is chosen to participate in an arbitration scheme; the tag picking a first random value from a first number of values, the first number of values being determined using at least one field of the first set of fields, the first random value corresponding to a first slot value in accordance with the arbitration scheme; the tag backscattering a reply to the interrogator during a first period of time in accordance with the arbitration scheme; sending a second command from the interrogator in response to the reply, the second command including a second set of fields; the tag wirelessly receiving the second command; the tag picking a second random value from a second number of values, the second number of values being determined using at least one field of the second set of fields, wherein the second number of values varies from the first number of values, the second random value corresponding to a second slot value in accordance with the arbitration scheme; the tag backscattering a random number to the interrogator during a second period of time in accordance with the arbitration scheme, wherein the random number is independently generated by the tag; and sending an acknowledge command from the interrogator to the tag if the random number is received by the interrogator without detecting a collision. - View Dependent Claims (61, 62, 63, 64, 65, 66)
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67. A method comprising:
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transmitting a first command from an interrogator, the first command to choose a group of radio frequency identification (RFID) tags according to one or more fields of the first command; causing each respective tag of a first portion of the group of tags to backscatter a respective, independently generated random number in a first order determined, at least in part, by a respective first slot value randomly picked from a first number of values by each respective tag of the first portion in accordance with an arbitration scheme; causing each respective tag of a second portion of the group of tags to backscatter a respective, independently generated random number in a second order determined, at least in part, by a respective second slot value randomly picked from a second number of values by each respective tag of the second portion in accordance with the arbitration scheme, wherein the first number of values varies from the second number of values; acknowledging each respective tag of the group of tags; and causing each respective tag of the group of tags to backscatter at least a portion of a respective identification code that identifies a respective object to which each respective tag is affixed. - View Dependent Claims (68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78)
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Specification