Communications systems for radio frequency identification (RFID)
DCFirst 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.
2 Assignments
Litigations
0 Petitions
Reexamination
Accused Products
Abstract
A method of system 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 searched tree. The interrogator transmits a first request comprising a bit string comprising a plurality of bits for use in selecting one or more wireless identification devices to participate in a slotted anticollision algorithm. Wireless identification devices in a field of the interrogator use the bit string to determine whether or not they are selected for participation. Those wireless identification devices that are selected for participation respond to the interrogator in a slot with a certain probability in accordance with the slotted anticollision algorithm.
129 Citations
78 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.
-
7. A method of addressing messages from an interrogator to a selected one or more of a number of communications devices, the method comprising:
-
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)
-
-
12. A method of addressing messages from an interrogator to a selected one or more of a number of communications devices, the method comprising:
-
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; and
determining 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)
-
-
16. A method of addressing messages from an interrogator to a selected one or more of a number of RFID devices, the method comprising:
-
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)
-
- 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.
-
27. A system comprising:
-
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)
-
-
30. A system comprising:
-
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; and
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 by descending in the tree. - View Dependent Claims (31, 32, 33)
-
-
34. A system comprising:
-
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)
-
-
38. A system, comprising:
-
an interrogator comprising;
one or more antennas, a transmitter and a receiver coupled to the one or more antennas, and a controller coupled to the transmitter and the receiver, the controller to cause the transmitter to transmit, via the one or more antennas, an initial command to select one or more radio frequency identification (RFID) devices from among a potential plurality of RFID devices that are within communications range, the initial command specifying a bit string having multiple bits; and
the one or more RFID devices, each respective device of the one or more RFID devices including;
memory to store a respective identification code, a receiver to receive the initial command from the interrogator, a circuit to compare the bit string specified in the initial command against corresponding bits stored in the respective device to determine whether the respective device is a member of a population of RFID devices selected according to the initial command, and if the respective device is a member of the population, pick a respective random value from a range of values to determine a respective slot, and a transmitter to communicate a respective reply, including at least a portion of an identifier of the respective device, to the interrogator in accordance with the respective slot. - View Dependent Claims (39, 40, 41, 42, 43)
-
-
44. A system comprising:
-
an interrogator having a transmitter to send an initial command to select one or more radio frequency identification (RFID) devices, the initial command specifying a bit string having multiple bits; and
an RFID device comprising;
a device memory to store a plurality of bits, a receiver to receive the initial command, a circuit to, in response to the initial command, determine whether the RFID device is selected via a comparison between the bit string and the plurality of bits stored in the memory and, if the RFID device is determined to be selected, communicate a response in accordance with a slotted anticollision algorithm, and a transmitter to communicate one or more identifiers of the RFID device to the interrogator in accordance with the slotted anticollision algorithm, wherein in accordance with the slotted anticollision algorithm the transmitter is to communicate the one or more identifiers in a time slot with a certain probability. - View Dependent Claims (45, 46, 47, 48, 49)
-
-
50. A system, comprising:
a radio frequency identification (RFID) device disposed in a communication field of an interrogator, the RFID device including;
a receiver to receive a first command from the interrogator after the RFID device is disposed in the field and before the interrogator transmits any other command, the first command specifying a bit string comprising two or more bits, a circuit to, in response to the first command, use the bit string to determine if the RFID device is selected for participation in a slotted anticollision algorithm, and a transmitter to communicate one or more responses to the interrogator in accordance with the slotted anticollision algorithm if the RFID device is determined to be selected for participation in the slotted anticollision algorithm, wherein the one or more responses include at least a portion of a first identifier and at least a portion of a second identifier stored in the RFID device. - View Dependent Claims (51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
-
65. A system comprising:
-
an interrogator including;
at least one antenna to provide a radio frequency (RF) field, a plurality of radio frequency identification (RFID) devices to modulate the RF field to transmit responses to the interrogator;
a transmitter to send a first signal after the plurality of RFID devices are disposed in the field and before any of the plurality of RFID devices transmit responses to the interrogator, the first signal including a bit string comprising multiple bits; and
a receiver to receive responses to the first signal in accordance with a slotted anticollision algorithm;
wherein the plurality of RFID devices include;
a first RFID device configured to store a first set of bits, receive the first signal and determine if the first RFID device is selected by the interrogator, including comparing the bit string with the first set of bits, and if so, pick a first random integer from a variable range of random integers and associate the first random integer with a first time slot in accordance with the anticollision algorithm, and modulate the RF field to communicate a first identification code of the first RFID device during the first time slot; and
a second RFID device to store a second set of bits, receive the first signal and determine if the second device is selected by the interrogator, including comparing the bit string with the second set of bits, and if so, pick a second random integer from a variable range of random integers and associate the second random integer with a second time slot in accordance with the anticollision algorithm, and modulate the RF field to communicate a second identification code of the second RFID device during the second time slot. - View Dependent Claims (66, 67, 68, 69, 70, 71)
-
-
72. A system comprising:
-
an interrogator including;
an antenna to provide a radio frequency (RF) field to interrogate;
a transmitter to send an initial command to identify radio frequency identification (RFID) devices disposed in the field, the initial command to be sent after the RFID devices are disposed in the field and before any of the RFID devices communicate any responses to the interrogator, the initial command to include a first specifying a plurality of bit values to select one or more of the RFID devices to participate in a slotted anticollision algorithm; and
a receiver to receive responses to the initial command in accordance with the slotted anticollision algorithm; and
an RFID device disposed in the RF field of the interrogator, the RFID device comprising;
a receiver to wirelessly receive the initial command;
a random number generator to randomly select an integer value from a range of integer values in accordance with the slotted anticollision algorithm, the range to be adjustable and to be indicated to the RFID device by the interrogator; and
a transmitter to modulate the RF field to communicate a one or more responses to the interrogator based at least in part on whether the plurality of bit values received from the interrogator identify the RFID device for response, wherein the one or more responses are to include a first identifier and are to be communicated in accordance with the randomly selected integer value in accordance with the slotted anticollision algorithm. - View Dependent Claims (73, 74, 75, 76, 77, 78)
-
Specification