Method of Addressing Messages and Communications System
First Claim
1. A method, comprising:
- transmitting a first command from an interrogator in accordance with a first loop of an algorithm to identify a radio frequency identification (RFID) device, the first command comprising a field indicating that no number of valid bits of a comparison value are transmitted with the first command;
responsive to the first command, receiving a first reply from the RFID device, the first reply comprising a first identifier of the RFID device;
transmitting a second command from the interrogator in accordance with a second loop of the algorithm if the interrogator detects a collision in the first reply, the second command comprising a field indicating that one or more valid bits of the comparison value are transmitted with the second command, wherein the RFID device compares the valid bits of the comparison value with a portion of the first identifier, and, if equal, modulates an RF field provided by the interrogator to communicate a second reply to the interrogator in accordance with the algorithm, the second reply comprising at least a portion of the first identifier; and
transmitting an indication of a number of time slots in which the interrogator is to receive one or more responses from one or more RFID devices in a field of the interrogator, and in response, receiving the one or more responses in one or more time slots of the number of time slots, wherein each of the one or more responses comprises a second identifier of each of the one or more RFID devices, respectively.
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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 combining tree search and Aloha methods to establish communications between the interrogator and individual ones of the multiple wireless identification devices without collision. A 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 tree search and Aloha techniques 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.
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Citations
59 Claims
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1. A method, comprising:
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transmitting a first command from an interrogator in accordance with a first loop of an algorithm to identify a radio frequency identification (RFID) device, the first command comprising a field indicating that no number of valid bits of a comparison value are transmitted with the first command; responsive to the first command, receiving a first reply from the RFID device, the first reply comprising a first identifier of the RFID device; transmitting a second command from the interrogator in accordance with a second loop of the algorithm if the interrogator detects a collision in the first reply, the second command comprising a field indicating that one or more valid bits of the comparison value are transmitted with the second command, wherein the RFID device compares the valid bits of the comparison value with a portion of the first identifier, and, if equal, modulates an RF field provided by the interrogator to communicate a second reply to the interrogator in accordance with the algorithm, the second reply comprising at least a portion of the first identifier; and transmitting an indication of a number of time slots in which the interrogator is to receive one or more responses from one or more RFID devices in a field of the interrogator, and in response, receiving the one or more responses in one or more time slots of the number of time slots, wherein each of the one or more responses comprises a second identifier of each of the one or more RFID devices, respectively. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A radio frequency identification (RFID) device, comprising:
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a receiver to receive first and second commands, the first command to include an indication of a first number of valid bits of an identification number and, if the first number of valid bits is indicated to be greater than zero, the valid bits of the identification number itself, and the second command to include an indication of a first number of time slots in which the RFID device is to respond; a memory to store a first identifier; and a transmitter to communicate a first response to the first command if the valid bits of the identification number, if any, match an equal number of bits of the first identifier stored in the memory, and to communicate a second response to the second command in a randomly selected time slot of the indicated first number of time slots, wherein the first response includes at least a portion of the first identifier. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An initiating wireless device to initiate wireless communication with a target radio frequency identification (RFID) device, comprising:
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a transmitter to transmit a first portion of a set of identifiers and to indicate a first number of time slots; an antenna to provide an RF field to be modulated by a target RFID device to communicate signals to the initiating device; a receiver to receive a response from a target RFID device that has an identifier in the set and to receive one or more identifiers from one or more target RFID devices during a time slot randomly selected from the first number of time slots by each of the one or more target RFID devices, respectively; and processing circuitry to perform collision detection on the response, to cause the transmitter to transmit a second portion of a subset of the set of identifiers if a collision is detected on the response, and to determine the identifier of the target RFID device using the response if no collision is detected on the response. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A target radio frequency identification (RFID) device, comprising:
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a receiver to receive an indication of a first number of valid bits common to a first set of identifiers, to receive the valid bits common to the first set if the first number is greater than zero, and to receive a signal indicating a change in a number of time slots from a first number of a plurality of time slots to a second number of a plurality of time slots in which the target device may respond; a memory to store an identifier; processing circuitry to determine if the identifier is in the first set, to generate a random value, and to randomly select a time slot; and a transmitter to communicate a response if the identifier is determined to be in the first set, and to communicate the response during the randomly selected time slot. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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49. A radio frequency identification (RFID) device, comprising:
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memory storing a unique number to identify to a person with whom the RFID device is associated; a receiver coupled to an antenna to receive requests comprising values having varying numbers of valid bits in accordance with a first method to wirelessly identify the RFID device, and time slot information in accordance with a second method to wirelessly identify the RFID device; a modulating circuit to modulate RF fields to communicate responses, wherein the responses comprise the unique number and an identifier of the RFID device; and processing circuitry to cause the modulating circuit to communicate responses based, at least in part, on comparisons between the valid bits of the values and bits of the identifier of the RFID device in accordance with the first method, and to cause the modulating circuit to communicate responses at time slots randomly selected using the time slot information in accordance with the second method. - View Dependent Claims (50, 51, 52, 53, 54, 55, 56, 57, 58, 59)
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Specification