USRE40686E1 - Method of addressing messages and communications system - Google Patents

Method of addressing messages and communications system Download PDF

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USRE40686E1
USRE40686E1 US10/652,573 US65257303A USRE40686E US RE40686 E1 USRE40686 E1 US RE40686E1 US 65257303 A US65257303 A US 65257303A US RE40686 E USRE40686 E US RE40686E
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interrogator
devices
command
random values
reply
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US10/652,573
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Clifton W. Wood, Jr.
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Boeing Co
Round Rock Research LLC
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Keystone Technology Solutions LLC
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Assigned to KEYSTONE TECHNOLOGY SOLUTIONS, LLC reassignment KEYSTONE TECHNOLOGY SOLUTIONS, LLC ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MICRON TECHNOLOGY, INC.
Priority to US11/862,121 priority patent/USRE41471E1/en
Priority to US11/862,124 priority patent/USRE41352E1/en
Publication of USRE40686E1 publication Critical patent/USRE40686E1/en
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Priority to US12/541,882 priority patent/USRE42599E1/en
Assigned to ROUND ROCK RESEARCH, LLC reassignment ROUND ROCK RESEARCH, LLC ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MICRON TECHNOLOGY, INC.
Assigned to MICRON TECHNOLOGY, INC. reassignment MICRON TECHNOLOGY, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KEYSTONE TECHNOLOGY SOLUTIONS, LLC
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W4/00Services specially adapted for wireless communication networks; Facilities therefor
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L41/00Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
    • H04L41/08Configuration management of networks or network elements
    • H04L41/0893Assignment of logical groups to network elements
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L41/00Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
    • H04L41/12Discovery or management of network topologies

Definitions

  • More than one reissue application has been filed for the reissue of U.S. Pat. No. 6 , 282 , 186 .
  • the reissue applications are the initial reissue application Ser. No. 10 / 652 , 573 filed Aug. 28 , 2003 , a continuation reissue application Ser. No. 11 / 862 , 121 filed Sep. 26 , 2007 , a continuation reissue application Ser. No. 11 / 862 , 124 filed Sep. 26 , 2007 , and a continuation reissue application Ser. No. 11 / 862 , 130 filed Sep. 26 , 2007 .
  • This invention relates to communications protocols and to digital data communications. Still more particularly, the invention relates to data communications protocols in mediums such as radio communication or the like. The invention also relates to radio frequency identification devices for inventory control, object monitoring, determining the existence, location or movement of objects, or for remote automated payment.
  • Communications protocols are used in various applications. For example, communications protocols can be used in electronic identification systems. As large numbers of objects are moved in inventory, product manufacturing, and merchandising operations, there is a continuous challenge to accurately monitor the location and flow of objects. Additionally, there is a continuing goal to interrogate the location of objects in an inexpensive and streamlined manner. One way of tracking objects is with an electronic identification system.
  • an identification device may be provided with a unique identification code in order to distinguish between a number of different devices.
  • the devices are entirely passive (have no power supply), which results in a small and portable package.
  • identification systems are only capable of operation over a relatively short range, limited by the size of a magnetic field used to supply power to the devices and to communicate with the devices.
  • Another wireless electronic identification system utilizes a large, board level, active transponder device affixed to an object to be monitored which receives a signal from an interrogator. The device receives the signal, then generates and transmits a responsive signal.
  • the interrogation signal and the responsive signal are typically radio-frequency (RF) signals produced by an RF transmitter circuit.
  • RF radio-frequency
  • Electronic identification systems can also be used for remote payment.
  • the toll both can determine the identity of the radio frequency identification device, and thus of the owner of the device, and debit an account held by the owner for payment of toll or can receive a credit card number against which the toll can be charged.
  • remote payment is possible for a variety of other goods or services.
  • a communication system typically includes two transponders: a commander station or interrogator, and a responder station or transponder device which replies to the interrogator.
  • the interrogator If the interrogator has prior knowledge of the identification number of a device which the interrogator is looking for, it can specify that a response is requested only from the device with that identification number. Sometimes, such information is not available. For example, there are occasions where the interrogator is attempting to determine which of multiple devices are within communication range.
  • the interrogator When the interrogator sends a message to a transponder device requesting a reply, there is a possibility that multiple transponder devices will attempt to respond simultaneously, causing a collision, and thus causing an erroneous message to be received by the interrogator. For example, if the interrogator sends out a command requesting that all devices within a communications range identify themselves, and gets a large number of simultaneous replies, the interrogator may not be able to interpret any of these replies. Thus, arbitration schemes are employed to permit communications free of collisions.
  • the interrogator sends a command causing each device of a potentially large number of responding devices to select a random number from a known range and use it as that device's arbitration number.
  • the interrogator determines the arbitration number of every responder station capable of communicating at the same time. Therefore, the interrogator is able to conduct subsequent uninterrupted communication with devices, one at a time, by addressing only one device.
  • Aloha Another arbitration scheme is referred to as the Aloha or slotted Aloha scheme.
  • This scheme is discussed in various references relating to communications, such as Digital Communications: Fundamentals and Application, Bernard Sklar, published January 1988 by Prentice Hall.
  • a device will respond to an interrogator using one of many time domain slots selected randomly by the device.
  • a problem with the Aloha scheme is that if there are many devices, or potentially many devices in the field (i.e. in communications range, capable of responding) then there must be many available slots or many collisions will occur. Having many available slots slows down replies. If the magnitude of the number of devices in a field is unknown, then many slots are needed. This results in the system slowing down significantly because the reply time equals the number of slots multiplied by the time period required for one reply.
  • the invention provides a wireless identification device configured to provide a signal to identify the device in response to an interrogation signal.
  • One aspect of the invention provides a method of establishing wireless communications between an interrogator and individual ones of multiple wireless identification devices.
  • the method comprises 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 is defined for the tree search method.
  • the tree has multiple nodes respectively representing subgroups of the multiple wireless identification devices.
  • the interrogator transmits a command at a node, requesting that devices within the subgroup represented by the node respond.
  • the interrogator determines if a collision occurs in response to the command and, if not, repeats the command at the same node.
  • Another aspect of the invention provides a communications system comprising an interrogator, and a plurality of wireless identification devices configured to communicate with the interrogator in a wireless fashion.
  • the interrogator is 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 is configured to follow a search tree, the tree having multiple nodes respectively representing subgroups of the multiple wireless identification devices.
  • the interrogator is configured to transmit a command at a node, requesting that devices within the subgroup represented by the node respond.
  • the interrogator is further configured to determine if a collision occurs in response to the command and, if not, to repeat the command at the same node.
  • a radio frequency identification device comprising an integrated circuit including a receiver, a transmitter, and a microprocessor.
  • the integrated circuit is a monolithic single die single metal layer integrated circuit including the receiver, the transmitter, and the microprocessor.
  • the device of this embodiment includes an active transponder, instead of a transponder which relies on magnetic coupling for power and therefore has a much greater range.
  • FIG. 1 is a high level circuit schematic showing an interrogator and a radio frequency identification device embodying the invention.
  • FIG. 2 is a front view of a housing, in the form of a badge or card, supporting the circuit of FIG. 1 according to one embodiment the invention.
  • FIG. 3 is a front view of a housing supporting the circuit of FIG. 1 according to another embodiment of the invention.
  • FIG. 4 is a diagram illustrating a tree splitting sort method for establishing communication with a radio frequency identification device in a field of a plurality of such devices.
  • FIG. 5 is a diagram illustrating a modified tree splitting sort method for establishing communication with a radio frequency identification device in a field of a plurality of such devices.
  • FIG. 1 illustrates a wireless identification device 12 in accordance with one embodiment of the invention.
  • the wireless identification device is a radio frequency data communication device 12 , and includes RFID circuitry 16 .
  • the device 12 further includes at least one antenna 14 connected to the circuitry 16 for wireless or radio frequency transmission and reception by the circuitry 16 .
  • the RFID circuitry is defined by an integrated circuit as described in the above-incorporated patent application Ser. No. 08/705,043, filed Aug. 29, 1996. Other embodiments are possible.
  • a power source or supply 18 is connected to the integrated circuit 16 to supply power to the integrated circuit 16 .
  • the power source 18 comprises a battery.
  • the device 12 transmits and receives radio frequency communications to and from an interrogator 26 .
  • An exemplary interrogator is described in commonly assigned U.S. patent application Ser. No. 08/907,689, filed Aug. 8, 1997 and incorporated herein by reference.
  • the interrogator 26 includes an antenna 28 , as well as dedicated transmitting and receiving circuitry, similar to that implemented on the integrated circuit 16 .
  • the interrogator 26 transmits an interrogation signal or command 27 via the antenna 28 .
  • the device 12 receives the incoming interrogation signal via its antenna 14 .
  • the device 12 responds by generating and transmitting a responsive signal or reply 29 .
  • the responsive signal 29 typically includes information that uniquely identifies, or labels the particular device 12 that is transmitting, so as to identify any object or person with which the device 12 is associated.
  • FIG. 1 typically there will be multiple devices 12 that correspond with the interrogator 26 , and the particular devices 12 that are in communication with the interrogator 26 will typically change over time. In the illustrated embodiment in FIG. 1 , there is no communication between multiple devices 12 . Instead, the devices 12 respectively communicate with the interrogator 26 .
  • Multiple devices 12 can be used in the same field of an interrogator 26 (i.e., within communications range of an interrogator 26 ).
  • the radio frequency data communication device 12 can be included in any appropriate housing or packaging. Various methods of manufacturing housings are described in commonly assigned U.S. patent application Ser. No. 08/800,037, filed Feb. 13, 1997, and incorporated herein by reference.
  • FIG. 2 shows but one embodiment in the form of a card or badge 19 including a housing 11 of plastic or other suitable material supporting the device 12 and the power supply 18 .
  • the front face of the badge has visual identification features such as graphics, text, information found on identification or credit cards, etc.
  • FIG. 3 illustrates but one alternative housing supporting the device 12 . More particularly, FIG. 3 shows a miniature housing 20 encasing the device 12 and power supply 18 to define a tag which can be supported by an object (e.g., hung from an object, affixed to an object, etc.). Although two particular types of housings have been disclosed, other forms of housings are employed in alternative embodiments.
  • the battery can take any suitable form.
  • the battery type will be selected depending on weight, size, and life requirements for a particular application.
  • the battery 18 is a thin profile button-type cell forming a small, thin energy cell more commonly utilized in watches and small electronic devices requiring a thin profile.
  • a conventional button-type cell has a pair of electrodes, an anode formed by one face and a cathode formed by an opposite face.
  • the power source 18 comprises a series connected pair of button type cells. In other alternative embodiments, other types of suitable power source are employed.
  • the circuitry 16 further includes a backscatter transmitter and is configured to provide a responsive signal to the interrogator 26 by radio frequency. More particularly, the circuitry 16 includes a transmitter, a receiver, and memory such as is described in U.S. patent application Ser. No. 08/705,043.
  • the interrogator 26 communicates with the devices 12 via an electromagnetic link, such as via an RF link (e.g., at microwave frequencies, in one embodiment), so all transmissions by the interrogator 26 are heard simultaneously by all devices 12 within range.
  • an electromagnetic link such as via an RF link (e.g., at microwave frequencies, in one embodiment)
  • the interrogator 26 sends out a command requesting that all devices 12 within range identify themselves, and gets a large number of simultaneous replies, the interrogator 26 may not be able to interpret any of these replies. Therefore, arbitration schemes are provided.
  • the interrogator 26 can specify that a response is requested only from the device 12 with that identification number.
  • the interrogator 26 To target a command at a specific device 12 , (i.e., to initiate point-on-point communication), the interrogator 26 must send a number identifying a specific device 12 along with the command. At start-up, or in a new or changing environment, these identification numbers are not known by the interrogator 26 . Therefore, the interrogator 26 must identify all devices 12 in the field (within communication range) such as by determining the identification numbers of the devices 12 in the field. After this is accomplished, point-to-point communication can proceed as desired by the interrogator 26 .
  • RFID systems are a type of multiaccess communication system.
  • the distance between the interrogator 26 and devices 12 within the field is typically fairly short (e.g., several meters), so packet transmission time is determined primarily by packet size and baud rate. Propagation delays are negligible.
  • packet transmission time is determined primarily by packet size and baud rate. Propagation delays are negligible.
  • the inventors have determined that the use of random access methods work effectively for contention resolution (i.e., for dealing with collisions between devices 12 attempting to respond to the interrogator 26 at the same time).
  • RFID systems have some characteristics that are different from other communications systems.
  • one characteristic of the illustrated RFID systems is that the devices 12 never communicate without being prompted by the interrogator 26 . This is in contrast to typical multiaccess systems where the transmitting units operate more independently.
  • contention for the communication medium is short lived as compared to the ongoing nature of the problem in other multiaccess systems.
  • the interrogator can communicate with them in a point-to-point fashion.
  • arbitration in a RFID system is a transient rather than steady-state phenomenon.
  • the capability of a device 12 is limited by practical restrictions on size, power, and cost. The lifetime of a device 12 can often be measured in terms of number of transmissions before battery power is lost. Therefore, one of the most important measures of system performance in RFID arbitration is total time required to arbitrate a set of devices 12 . Another measure is power consumed by the devices 12 during the process. This is in contrast to the measures of throughput and packet delay in other types of multiaccess systems.
  • FIG. 4 illustrates one arbitration scheme that can be employed for communication between the interrogator and devices 12 .
  • the interrogator 26 sends a command causing each device 12 of a potentially large number of responding devices 12 to select a random number from a known range and use it as that device's arbitration number.
  • the interrogator 26 determines the arbitration number of every responder station capable of communicating at the same time. Therefore, the interrogator 26 is able to conduct subsequent underrupted communication with devices 12 , one at a time, by addressing only one device 12 .
  • the interrogator sends an Identify command (IdentifyCmnd) causing each device of a potentially large number of responding devices to select a random number from a known range and use it as that device's arbitration number.
  • the interrogator sends an arbitration value (AVALUE) and an arbitration mask (AMASK) to a set of devices 12 .
  • sixteen bits are used for AVALUE and AMASK.
  • Other numbers of bits can also be employed depending, for example, on the number of devices 12 expected to be encountered in a particular application, on desired cost points, etc.
  • the interrogator sets AVALUE to 0000 (or “don't care” for all bits, as indicated by the character “X” in FIG. 4 ) and AMASK to 0000.
  • the interrogator transmits a command to all devices 12 requesting that they identify themselves.
  • AMASK is 0000 and anything bitwise ANDed with all zeros results in all zeros, so both the devices 12 in the field respond, and there is a collision.
  • the interrogator sets AMASK to 0001 and AVALUE to 0000 and transmits an identify command.
  • the left side equals the right side, so the equation is true for the device 12 with the random value of 1100.
  • the left side equals the right side, so the equation is true for the device 12 with the random value of 1010. Because the equation is true for both devices 12 in the field, both devices 12 in the field respond, and there is another collision.
  • the interrogator next sets AMASK to 0011 with AVALUE still at 0000 and transmits an Identify command.
  • the left side equals the right side, so the equation is true for the device 12 with the random value of 1100, so this device 12 responds.
  • the left side does not equal the right side, so the equation is false for the device 12 with the random value of 1010, and this device 12 does not respond. Therefore, there is no collision, and the interrogator can determine the identity (e.g., an identification number) for the device 12 that does respond.
  • the identity e.g., an identification number
  • De-recursion takes place, and the devices 12 to the right for the same AMASK level are accessed when AVALUE is set at 0010, and AMASK is set to 0011.
  • the right side equals the left side, so the equation is true for the device 12 with the random value of 1010. Because there are no other devices 12 in the subtree, a good reply is returned by the device 12 with the random value of 1010. There is no collision, and the interrogator 26 can determine the identity (e.g., an identification number) for the device 12 that does respond.
  • identity e.g., an identification number
  • recursion what is meant is that a function makes a call to itself. In other words, the function calls itself within the body of the function. After the called function returns, de-recursion takes place and execution continues at the place just after the function call; i.e. at the beginning of the statement after the function call.
  • Arbitrate(AMASK,AVALUE) ⁇ collision IdentifyCmnd(AMASK, AVALUE) if (collision) then ⁇ /* recursive call for left side */ Arbitrate ((AMASK ⁇ 1)+1, AVALUE) /* recursive call for right side */ Arbitrate ((AMASK ⁇ 1)+1, AVALUE+(AMASK+1)) ⁇ /* endif */ ⁇ /* return */
  • the routine generates values for AMASK and AVALUE to be used by the interrogator in an Identify command “IdentifyCmnd.” Note that the routine calls itself if there is a collision. De-recursion occurs when there is no collision. AVALUE and AMASK would have values such as the following assuming collisions take place all the way down to the bottom of the tree.
  • This method is referred to as a splitting method. It works by splitting groups of colliding devices 12 into subsets that are resolved in turn.
  • the splitting method can also be viewed as a type of tree search. Each split moves the method one level deeper in the tree. Either depth-first or breadth-first traversals of the tree can be employed. Depth first traversals are performed by using recursion, as is employed in the code listed above. Breadth-first traversals are accomplished by using a queue instead of recursion.
  • Either depth-first or breadth-first traversals of the tree can be employed. Depth first traversals are performed by using recursion, as is employed in the code listed above. Breadth-first traversals are accomplished by using a queue instead of recursion. The following is an example of code for performing a breadth-first traversal.
  • AVALUE and AMASK would have values such as those indicated in the following table for such code.
  • Rows in the table for which the interrogator is successful in receiving a reply without collision are marked with the symbol “*”.
  • FIG. 5 illustrates an embodiment wherein the interrogator 26 retries on the same node that yielded a good reply.
  • the search tree has a plurality of nodes 51 , 52 , 53 , 54 etc. at respective levels 32 , 34 , 36 , 38 , or 40 .
  • the size of subgroups of random values decrease in size by half with each node descended.
  • the interrogator performs a tree search, either depth-first or breadth-first in a manner such as that described in connection with FIG. 4 , except that if the interrogator determines that no collision occurred in response to an identify command, the interrogator repeats the command at the same node.
  • the method described in connection with FIG. 4 would involve proceeding to node 53 and then sending another Identify command. Because a device 12 in a field of devices 12 can override weaker devices, this embodiment is modified such that the interrogator retries on the same node 52 after silencing the device 12 that gave the good reply. Thus, after receiving a good reply from node 52 , the interrogator remains on node 52 and reissues the Identify command after silencing the device that first responded on node 52 . Repeating the Identify command on the same node often yields other good replies, thus taking advantage of the devices natural ability to self-arbitrate.
  • AVALUE and AMASK would have values such as the following for a depth-first traversal in a situation similar to the one described above in connection with FIG. 4 .
  • Rows in the table for which the interrogator is successful in receiving a reply without collision are marked with the symbol “*”.
  • the interrogator transmits a command at a node, requesting that devices within the subgroup represented by the node respond.
  • the interrogator determines if a collision occurs in response to the command and, if not, repeats the command at the same node.
  • the upper bound of the number of devices in the field (the maximum possible number of devices that could communicate with the interrogator) is determined, and the tree search method is started at a level 32 , 34 , 36 , 38 , or 40 in the tree depending on the determined upper bound.
  • the level of the search tree on which to start the tree search is selected based on the determined maximum possible number of wireless identification devices that could communicate with the interrogator.
  • the tree search is started at a level determined by taking the base two logarithm of the determined maximum possible number. More particularly, the tree search is started at a level determined by taking the base two logarithm of the power of two nearest the determined maximum possible number of devices 12 .
  • the level of the tree containing all subgroups of random values is considered level zero, and lower levels are numbered 1, 2, 3, 4, etc. consecutively.
  • a method involving starting at a level in the tree depending on a determined upper bound is combined with a method comprising re-trying on the same node that gave a good reply, such as the method shown and described in connection with FIG. 5 .
  • Aloha Another arbitration method that can be employed is referred to as the “Aloha” method.
  • Aloha every time a device 12 is involved in a collision, it waits a random period of time before retransmitting. This method can be improved by dividing time into equally sized slots and forcing transmissions to be aligned with one of these slots. This is referred to as “slotted Aloha.”
  • the interrogator asks all devices 12 in the field to transmit their identification numbers in the next time slot. If the response is garbled, the interrogator informs the devices 12 that a collision has occurred, and the slotted Aloha scheme is put into action. This means that each device 12 in the field responds within an arbitrary slot determined by a randomly selected value. In other words, in each successive time slot, the devices 12 decide to transmit their identification number with a certain probability.
  • the Aloha method is based on a system operated by the University of Hawaii. In 1971, the University of Hawaii began operation of a system named Aloha.
  • a communication satellite was used to interconnect several university computers by use of a random access protocol.
  • the system operates as follows. Users or devices transmit at any time they desire. After transmitting, a user listens for an acknowledgment from the receiver or interrogator. Transmissions from different users will sometimes overlap in time (collide), causing reception errors in the data in each of the contending messages. The errors are detected by the receiver, and the receiver sends a negative acknowledgment to the users. When a negative acknowledgment is received, the messages are retransmitted by the colliding users after a random delay. If the colliding users attempted to retransmit without the random delay, they would collide again. If the user does not receive either an acknowledgment or a negative acknowledgment within a certain amount of time, the user “times out” and retransmits the message.
  • slotted Aloha There is a scheme known as slotted Aloha which improves the Aloha scheme by requiring a small amount of coordination among stations.
  • a sequence of coordination pulses is broadcast to all stations (devices).
  • packet lengths are constant. Messages are required to be sent in a slot time between synchronization pulses, and can be started only at the beginning of a time slot. This reduces the rate of collisions because only messages transmitted in the same slot can interfere with one another.
  • the retransmission mode of the pure 11 Aloha scheme is modified for slotted Aloha such that if a negative acknowledgment occurs, the device retransmits after a random delay of an integer number of slot times.
  • an Aloha method (such as the method described in the commonly assigned patent application mentioned above) is combined with a method involving re-trying on the same node that gave a good reply, such as the method shown and described in connection with FIG. 5 .
  • levels of the search tree are skipped. Skipping levels in the tree, after a collision caused by multiple devices 12 responding, reduces the number of subsequent collisions without adding significantly to the number of no replies. In real-time systems, it is desirable to have quick arbitration sessions on a set of devices 12 whose unique identification numbers are unknown. Level skipping reduces the number of collisions, both reducing arbitration time and conserving battery life on a set of devices 12 . In one embodiment, every other level is skipped. In alternative embodiments, more than one level is skipped each time.
  • Skipping levels reduces the number of collisions, thus saving battery power in the devices 12 . Skipping deeper (skipping more than one level) further reduces the number of collisions. The more levels that are skipped, the greater the reduction in collisions. However, skipping levels results in longer search times because the number of queries (Identify commands) increases. The more levels that are skipped, the longer the search times. Skipping just one level has an almost negligible effect on search time, but drastically reduces the number of collisions. If more than one level is skipped, search time increases substantially. Skipping every other level drastically reduces the number of collisions and saves battery power without significantly increasing the number of queries.
  • a level skipping method is combined with a method involving re-trying on the same node that gave a good reply, such as the method shown and described in connection with FIG. 5 .

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 the 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.

Description

CROSS REFERENCE TO RELATED APPLICATION
This is a Continuation of U.S. patent application Ser. No. 09/026,050, filed Feb. 19, 1998, now U.S. Pat. No. 6,061,344 and titled “Method of Addressing Messages and Communications System”.
RELATED REISSUE APPLICATIONS
More than one reissue application has been filed for the reissue of U.S. Pat. No. 6,282,186. The reissue applications are the initial reissue application Ser. No. 10/652,573 filed Aug. 28, 2003, a continuation reissue application Ser. No. 11/862,121 filed Sep. 26, 2007, a continuation reissue application Ser. No. 11/862,124 filed Sep. 26, 2007, and a continuation reissue application Ser. No. 11/862,130 filed Sep. 26, 2007.
TECHNICAL FIELD
This invention relates to communications protocols and to digital data communications. Still more particularly, the invention relates to data communications protocols in mediums such as radio communication or the like. The invention also relates to radio frequency identification devices for inventory control, object monitoring, determining the existence, location or movement of objects, or for remote automated payment.
BACKGROUND OF THE INVENTION
Communications protocols are used in various applications. For example, communications protocols can be used in electronic identification systems. As large numbers of objects are moved in inventory, product manufacturing, and merchandising operations, there is a continuous challenge to accurately monitor the location and flow of objects. Additionally, there is a continuing goal to interrogate the location of objects in an inexpensive and streamlined manner. One way of tracking objects is with an electronic identification system.
One presently available electronic identification system utilizes a magnetic coupling system. In some cases, an identification device may be provided with a unique identification code in order to distinguish between a number of different devices. Typically, the devices are entirely passive (have no power supply), which results in a small and portable package. However, such identification systems are only capable of operation over a relatively short range, limited by the size of a magnetic field used to supply power to the devices and to communicate with the devices.
Another wireless electronic identification system utilizes a large, board level, active transponder device affixed to an object to be monitored which receives a signal from an interrogator. The device receives the signal, then generates and transmits a responsive signal. The interrogation signal and the responsive signal are typically radio-frequency (RF) signals produced by an RF transmitter circuit. Because active devices have their own power sources, and do not need to be in close proximity to an interrogator or reader to receive power via magnetic coupling. Therefore, active transponder devices tend to be more suitable for applications requiring tracking of a tagged device that may not be in close proximity to an interrogator. For example, active transponder devices tend to be more suitable for inventory control or tracking.
Electronic identification systems can also be used for remote payment. For example, when a radio frequency identification device passes an interrogator at a toll booth, the toll both can determine the identity of the radio frequency identification device, and thus of the owner of the device, and debit an account held by the owner for payment of toll or can receive a credit card number against which the toll can be charged. Similarly, remote payment is possible for a variety of other goods or services.
A communication system typically includes two transponders: a commander station or interrogator, and a responder station or transponder device which replies to the interrogator.
If the interrogator has prior knowledge of the identification number of a device which the interrogator is looking for, it can specify that a response is requested only from the device with that identification number. Sometimes, such information is not available. For example, there are occasions where the interrogator is attempting to determine which of multiple devices are within communication range.
When the interrogator sends a message to a transponder device requesting a reply, there is a possibility that multiple transponder devices will attempt to respond simultaneously, causing a collision, and thus causing an erroneous message to be received by the interrogator. For example, if the interrogator sends out a command requesting that all devices within a communications range identify themselves, and gets a large number of simultaneous replies, the interrogator may not be able to interpret any of these replies. Thus, arbitration schemes are employed to permit communications free of collisions.
In one arbitration scheme or system, described in commonly assigned U.S. Pat. Nos. 5,627,544; 5,583,850; 5,500,650; and 5,365,551, all to Snodgrass et al. and all incorporated herein by reference, the interrogator sends a command causing each device of a potentially large number of responding devices to select a random number from a known range and use it as that device's arbitration number. By transmitting requests for identification to various subsets of the full range of arbitration numbers, and checking for an error-free response, the interrogator determines the arbitration number of every responder station capable of communicating at the same time. Therefore, the interrogator is able to conduct subsequent uninterrupted communication with devices, one at a time, by addressing only one device.
Another arbitration scheme is referred to as the Aloha or slotted Aloha scheme. This scheme is discussed in various references relating to communications, such as Digital Communications: Fundamentals and Application, Bernard Sklar, published January 1988 by Prentice Hall. In this type of scheme, a device will respond to an interrogator using one of many time domain slots selected randomly by the device. A problem with the Aloha scheme is that if there are many devices, or potentially many devices in the field (i.e. in communications range, capable of responding) then there must be many available slots or many collisions will occur. Having many available slots slows down replies. If the magnitude of the number of devices in a field is unknown, then many slots are needed. This results in the system slowing down significantly because the reply time equals the number of slots multiplied by the time period required for one reply.
An electronic identification system which can be used as a radio frequency identification device, arbitration schemes, and various applications for such devices are described in detail in commonly assigned U.S. patent application Ser. No. 08/705,043, filed Aug. 29, 1996, and incorporated herein by reference.
SUMMARY OF THE INVENTION
The invention provides a wireless identification device configured to provide a signal to identify the device in response to an interrogation signal.
One aspect of the invention provides a method of establishing wireless communications between an interrogator and individual ones of multiple wireless identification devices. The method comprises 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 is defined for the tree search method. The tree has multiple nodes respectively representing subgroups of the multiple wireless identification devices. The interrogator transmits a command at a node, requesting that devices within the subgroup represented by the node respond. The interrogator determines if a collision occurs in response to the command and, if not, repeats the command at the same node.
Another aspect of the invention provides a communications system comprising an interrogator, and a plurality of wireless identification devices configured to communicate with the interrogator in a wireless fashion. The interrogator is 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 is configured to follow a search tree, the tree having multiple nodes respectively representing subgroups of the multiple wireless identification devices. The interrogator is configured to transmit a command at a node, requesting that devices within the subgroup represented by the node respond. The interrogator is further configured to determine if a collision occurs in response to the command and, if not, to repeat the command at the same node.
One aspect of the invention provides a radio frequency identification device comprising an integrated circuit including a receiver, a transmitter, and a microprocessor. In one embodiment, the integrated circuit is a monolithic single die single metal layer integrated circuit including the receiver, the transmitter, and the microprocessor. The device of this embodiment includes an active transponder, instead of a transponder which relies on magnetic coupling for power and therefore has a much greater range.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are described below with reference to the following accompanying drawings.
FIG. 1 is a high level circuit schematic showing an interrogator and a radio frequency identification device embodying the invention.
FIG. 2 is a front view of a housing, in the form of a badge or card, supporting the circuit of FIG. 1 according to one embodiment the invention.
FIG. 3 is a front view of a housing supporting the circuit of FIG. 1 according to another embodiment of the invention.
FIG. 4 is a diagram illustrating a tree splitting sort method for establishing communication with a radio frequency identification device in a field of a plurality of such devices.
FIG. 5. is a diagram illustrating a modified tree splitting sort method for establishing communication with a radio frequency identification device in a field of a plurality of such devices.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).
FIG. 1 illustrates a wireless identification device 12 in accordance with one embodiment of the invention. In the illustrated embodiment, the wireless identification device is a radio frequency data communication device 12, and includes RFID circuitry 16. The device 12 further includes at least one antenna 14 connected to the circuitry 16 for wireless or radio frequency transmission and reception by the circuitry 16. In the illustrated embodiment, the RFID circuitry is defined by an integrated circuit as described in the above-incorporated patent application Ser. No. 08/705,043, filed Aug. 29, 1996. Other embodiments are possible. A power source or supply 18 is connected to the integrated circuit 16 to supply power to the integrated circuit 16. In one embodiment, the power source 18 comprises a battery.
The device 12 transmits and receives radio frequency communications to and from an interrogator 26. An exemplary interrogator is described in commonly assigned U.S. patent application Ser. No. 08/907,689, filed Aug. 8, 1997 and incorporated herein by reference. Preferably, the interrogator 26 includes an antenna 28, as well as dedicated transmitting and receiving circuitry, similar to that implemented on the integrated circuit 16.
Generally, the interrogator 26 transmits an interrogation signal or command 27 via the antenna 28. The device 12 receives the incoming interrogation signal via its antenna 14. Upon receiving the signal 27, the device 12 responds by generating and transmitting a responsive signal or reply 29. The responsive signal 29 typically includes information that uniquely identifies, or labels the particular device 12 that is transmitting, so as to identify any object or person with which the device 12 is associated. Although only one device 12 is shown in FIG. 1, typically there will be multiple devices 12 that correspond with the interrogator 26, and the particular devices 12 that are in communication with the interrogator 26 will typically change over time. In the illustrated embodiment in FIG. 1, there is no communication between multiple devices 12. Instead, the devices 12 respectively communicate with the interrogator 26. Multiple devices 12 can be used in the same field of an interrogator 26 (i.e., within communications range of an interrogator 26).
The radio frequency data communication device 12 can be included in any appropriate housing or packaging. Various methods of manufacturing housings are described in commonly assigned U.S. patent application Ser. No. 08/800,037, filed Feb. 13, 1997, and incorporated herein by reference.
FIG. 2 shows but one embodiment in the form of a card or badge 19 including a housing 11 of plastic or other suitable material supporting the device 12 and the power supply 18. In one embodiment, the front face of the badge has visual identification features such as graphics, text, information found on identification or credit cards, etc.
FIG. 3 illustrates but one alternative housing supporting the device 12. More particularly, FIG. 3 shows a miniature housing 20 encasing the device 12 and power supply 18 to define a tag which can be supported by an object (e.g., hung from an object, affixed to an object, etc.). Although two particular types of housings have been disclosed, other forms of housings are employed in alternative embodiments.
If the power supply 18 is a battery, the battery can take any suitable form. Preferably, the battery type will be selected depending on weight, size, and life requirements for a particular application. In one embodiment, the battery 18 is a thin profile button-type cell forming a small, thin energy cell more commonly utilized in watches and small electronic devices requiring a thin profile. A conventional button-type cell has a pair of electrodes, an anode formed by one face and a cathode formed by an opposite face. In an alternative embodiment, the power source 18 comprises a series connected pair of button type cells. In other alternative embodiments, other types of suitable power source are employed.
The circuitry 16 further includes a backscatter transmitter and is configured to provide a responsive signal to the interrogator 26 by radio frequency. More particularly, the circuitry 16 includes a transmitter, a receiver, and memory such as is described in U.S. patent application Ser. No. 08/705,043.
Radio frequency identification has emerged as a viable and affordable alternative to tagging or labeling small to large quantities of items. The interrogator 26 communicates with the devices 12 via an electromagnetic link, such as via an RF link (e.g., at microwave frequencies, in one embodiment), so all transmissions by the interrogator 26 are heard simultaneously by all devices 12 within range.
If the interrogator 26 sends out a command requesting that all devices 12 within range identify themselves, and gets a large number of simultaneous replies, the interrogator 26 may not be able to interpret any of these replies. Therefore, arbitration schemes are provided.
If the interrogator 26 has prior knowledge of the identification number of a device 12 which the interrogator 26 is looking for, it can specify that a response is requested only from the device 12 with that identification number. To target a command at a specific device 12, (i.e., to initiate point-on-point communication), the interrogator 26 must send a number identifying a specific device 12 along with the command. At start-up, or in a new or changing environment, these identification numbers are not known by the interrogator 26. Therefore, the interrogator 26 must identify all devices 12 in the field (within communication range) such as by determining the identification numbers of the devices 12 in the field. After this is accomplished, point-to-point communication can proceed as desired by the interrogator 26.
Generally speaking, RFID systems are a type of multiaccess communication system. The distance between the interrogator 26 and devices 12 within the field is typically fairly short (e.g., several meters), so packet transmission time is determined primarily by packet size and baud rate. Propagation delays are negligible. In such systems, there is a potential for a large number of transmitting devices 12 and there is a need for the interrogator 26 to work in a changing environment, where different devices 12 are swapped in and out frequently (e.g., as inventory is added or removed). In such systems, the inventors have determined that the use of random access methods work effectively for contention resolution (i.e., for dealing with collisions between devices 12 attempting to respond to the interrogator 26 at the same time).
RFID systems have some characteristics that are different from other communications systems. For example, one characteristic of the illustrated RFID systems is that the devices 12 never communicate without being prompted by the interrogator 26. This is in contrast to typical multiaccess systems where the transmitting units operate more independently. In addition, contention for the communication medium is short lived as compared to the ongoing nature of the problem in other multiaccess systems. For example, in a RFID system, after the devices 12 have been identified, the interrogator can communicate with them in a point-to-point fashion. Thus, arbitration in a RFID system is a transient rather than steady-state phenomenon. Further, the capability of a device 12 is limited by practical restrictions on size, power, and cost. The lifetime of a device 12 can often be measured in terms of number of transmissions before battery power is lost. Therefore, one of the most important measures of system performance in RFID arbitration is total time required to arbitrate a set of devices 12. Another measure is power consumed by the devices 12 during the process. This is in contrast to the measures of throughput and packet delay in other types of multiaccess systems.
FIG. 4 illustrates one arbitration scheme that can be employed for communication between the interrogator and devices 12. Generally, the interrogator 26 sends a command causing each device 12 of a potentially large number of responding devices 12 to select a random number from a known range and use it as that device's arbitration number. By transmitting requests for identification to various subsets of the full range of arbitration numbers, and checking for an error-free response, the interrogator 26 determines the arbitration number of every responder station capable of communicating at the same time. Therefore, the interrogator 26 is able to conduct subsequent unterrupted communication with devices 12, one at a time, by addressing only one device 12.
Three variables are used: an arbitration value (AVALUE), an arbitration mask (AMASK), and a random value ID (RV). The interrogator sends an Identify command (IdentifyCmnd) causing each device of a potentially large number of responding devices to select a random number from a known range and use it as that device's arbitration number. The interrogator sends an arbitration value (AVALUE) and an arbitration mask (AMASK) to a set of devices 12. The receiving devices 12 evaluate the following equation: (AMASK & AVALUE)==(AMASK & RV) wherein “&” is a bitwise AND function, and wherein “==” is an equality function. If the equation evaluates to “1” (TRUE), then the device 12 will reply. If the equation evaluates to “0” (FALSE), then the device 12 will not reply. By performing this in a structured manner, with the number of bits in the arbitration mask being increased by one each time, eventually a device 12 will respond with no collisions. Thus, a binary search tree methodology is employed.
An example using actual numbers will now be provided using only four bits, for simplicity, reference being made to FIG. 4. In one embodiment, sixteen bits are used for AVALUE and AMASK. Other numbers of bits can also be employed depending, for example, on the number of devices 12 expected to be encountered in a particular application, on desired cost points, etc.
Assume, for this example, that there are two devices 12 in the field, one with a random value (RV) of 1100 (binary), and another with a random value (RV) of 1010 (binary). The interrogator is trying to establish communications without collisions being caused by the two devices 12 attempting to communicate at the same time.
The interrogator sets AVALUE to 0000 (or “don't care” for all bits, as indicated by the character “X” in FIG. 4) and AMASK to 0000. The interrogator transmits a command to all devices 12 requesting that they identify themselves. Each of the devices 12 evaluate (AMASK & AVALUE)==(AMASK & RV) using the random value RV that the respective devices 12 selected. If the equation evaluates to “1” (TRUE), then the device 12 will reply. If the equation evaluates to “0” (FALSE), then the device 12 will not reply. In the first level of the illustrated tree, AMASK is 0000 and anything bitwise ANDed with all zeros results in all zeros, so both the devices 12 in the field respond, and there is a collision.
Next, the interrogator sets AMASK to 0001 and AVALUE to 0000 and transmits an identify command. Both devices 12 in the field have a zero for their least significant bit, and (AMASK & AVALUE)==(AMASK & RV) will be true for both devices 12. For the device 12 with a random value of 1100, the left side of the equation is evaluated as follows (0001 & 0000)=0000.
The right side is evaluated as (0001 & 1100)=0000. The left side equals the right side, so the equation is true for the device 12 with the random value of 1100. For the device 12 with a random value of 1010, the left side of the equation is evaluated as (0001 & 0000)=0000. The right side is evaluated as (0001 & 1010)=0000. The left side equals the right side, so the equation is true for the device 12 with the random value of 1010. Because the equation is true for both devices 12 in the field, both devices 12 in the field respond, and there is another collision.
Recursively, the interrogator next sets AMASK to 0011 with AVALUE still at 0000 and transmits an Identify command. (AMASK & AVALUE)==(AMASK & RV) is evaluated for both devices 12. For the device 12 with a random value of 1100, the left side of the equation is evaluated as follows (0011 & 0000)=0000. The right side is evaluated as (0011 & 1100)=0000. The left side equals the right side, so the equation is true for the device 12 with the random value of 1100, so this device 12 responds. For the device 12 with a random value of 1010, the left side of the equation is evaluated as (0011 & 0000)=0000. The right side is evaluated as (0011 & 1010)=0010. The left side does not equal the right side, so the equation is false for the device 12 with the random value of 1010, and this device 12 does not respond. Therefore, there is no collision, and the interrogator can determine the identity (e.g., an identification number) for the device 12 that does respond.
De-recursion takes place, and the devices 12 to the right for the same AMASK level are accessed when AVALUE is set at 0010, and AMASK is set to 0011.
The device 12 with the random value of 1010 receives a command and evaluates the equation (AMASK & AVALUE)==(AMASK & RV). The left side of the equation is evaluated as (0011 & 0010)=0010. The right side of the equation is evaluated as (0011 & 1010)=0010. The right side equals the left side, so the equation is true for the device 12 with the random value of 1010. Because there are no other devices 12 in the subtree, a good reply is returned by the device 12 with the random value of 1010. There is no collision, and the interrogator 26 can determine the identity (e.g., an identification number) for the device 12 that does respond.
By recursion, what is meant is that a function makes a call to itself. In other words, the function calls itself within the body of the function. After the called function returns, de-recursion takes place and execution continues at the place just after the function call; i.e. at the beginning of the statement after the function call.
For instance, consider a function that has four statements (numbered 1,2,3,4) in it, and the second statement is a recursive call. Assume that the fourth statement is a return statement. The first time through the loop (iteration 1) the function executes the statement 2 and (because it is a recursive call) calls itself causing iteration 2 to occur. When iteration 2 gets to statement 2, it calls itself making iteration 3. During execution in iteration 3 of statement 1, assume that the function does a return. The information that was saved on the stack from iteration 2 is loaded and the function resumes execution at statement 3 (in iteration 2), followed by the execution of statement 4 which is also a return statement. Since there are no more statements in the function, the function de-recurses to iteration 1. Iteration 1, had previously recursively called itself in statement 2. Therefore, it now executes statement 3 (in iteration 1). Following that it executes a return at statement 4. Recursion is known in the art.
Consider the following code which can be used to implement operation of the method shown in FIG. 4 and described above.
Arbitrate(AMASK,AVALUE)
{
collision=IdentifyCmnd(AMASK, AVALUE) if
(collision) then
{
/* recursive call for left side */ Arbitrate
((AMASK<<1)+1, AVALUE)
/* recursive call for right side */ Arbitrate
((AMASK<<1)+1, AVALUE+(AMASK+1))
} /* endif */
}/* return */
The symbol “<<” represents a bitwise left shift. “<<1” means shift left by one place. Thus, 0001<<1 would be 0010. Note, however, that AMASK is originally called with a value of zero, and 0000<<1 is still 0000. Therefore, for the first recursive call, AMASK=(AMASK<<1)+1. So for the first recursive call, the value of AMASK is 0000+0001=0001. For the second call, AMASK=(0001<<)+1=0010+1=0011. For the third recursive call, AMASK=(0011<<1)+1=0110+1=0111.
The routine generates values for AMASK and AVALUE to be used by the interrogator in an Identify command “IdentifyCmnd.” Note that the routine calls itself if there is a collision. De-recursion occurs when there is no collision. AVALUE and AMASK would have values such as the following assuming collisions take place all the way down to the bottom of the tree.
AVALUE AMASK
0000 0000
0000 0001
0000 0011
0000 0111
0000  1111*
1000  1111*
0100 0111
0100  1111*
1100  1111*
This sequence of AMASK, AVALUE binary numbers assumes that there are collisions all the way down to the bottom of the tree, at which point the Identify command sent by the interrogator is finally successful so that no collision occurs. Rows in the table for which the interrogator is successful in receiving a reply without collision are marked with the symbol “*”. Note that if the Identify command was successful at, for example, the third line in the table then the interrogator would stop going down that branch of the tree and start down another, so the sequence would be as shown in the following table.
AVALUE AMASK
0000 0000
0000 0001
0000  0011*
0010 0111
This method is referred to as a splitting method. It works by splitting groups of colliding devices 12 into subsets that are resolved in turn. The splitting method can also be viewed as a type of tree search. Each split moves the method one level deeper in the tree. Either depth-first or breadth-first traversals of the tree can be employed. Depth first traversals are performed by using recursion, as is employed in the code listed above. Breadth-first traversals are accomplished by using a queue instead of recursion.
Either depth-first or breadth-first traversals of the tree can be employed. Depth first traversals are performed by using recursion, as is employed in the code listed above. Breadth-first traversals are accomplished by using a queue instead of recursion. The following is an example of code for performing a breadth-first traversal.
Arbitrate(AMASK,AVALUE)
{
 enqueue(0,0)
 while (queue I= empty)
(AMASK,AVALUE) = dequeue( )
collision=IdentifyCmnd(AMASK, AVALUE)
if (collision) then
{
 TEMP = AMASK+1
 NEW_AMASK = (AMASK<<1)+1
 enqueue(NEW_AMASK, AVALUE)
 enqueue(NEW_AMASK, AVALUE+TEMP)
} /* endif */
endwhile
}/* return */
The symbol “!=” means not equal to. AVALUE and AMASK would have values such as those indicated in the following table for such code.
AVALUE AMASK
0000 0000
0000 0001
0001 0001
0000 0011
0010 0011
0001 0011
0011 0011
0000 0111
0100 0111
Rows in the table for which the interrogator is successful in receiving a reply without collision are marked with the symbol “*”.
FIG. 5 illustrates an embodiment wherein the interrogator 26 retries on the same node that yielded a good reply. The search tree has a plurality of nodes 51, 52, 53, 54 etc. at respective levels 32, 34, 36, 38, or 40. The size of subgroups of random values decrease in size by half with each node descended.
The interrogator performs a tree search, either depth-first or breadth-first in a manner such as that described in connection with FIG. 4, except that if the interrogator determines that no collision occurred in response to an identify command, the interrogator repeats the command at the same node. This takes advantage of an inherent capability of the devices, particularly if the devices use backscatter communication, called self-arbitration. Arbitration times can be reduced, and battery life for the devices can be increased.
When a single reply is read by the interrogator, for example, in node 52, the method described in connection with FIG. 4 would involve proceeding to node 53 and then sending another Identify command. Because a device 12 in a field of devices 12 can override weaker devices, this embodiment is modified such that the interrogator retries on the same node 52 after silencing the device 12 that gave the good reply. Thus, after receiving a good reply from node 52, the interrogator remains on node 52 and reissues the Identify command after silencing the device that first responded on node 52. Repeating the Identify command on the same node often yields other good replies, thus taking advantage of the devices natural ability to self-arbitrate.
AVALUE and AMASK would have values such as the following for a depth-first traversal in a situation similar to the one described above in connection with FIG. 4.
AVALUE AMASK
0000 0000 
0000 0001 
0000 0011 
0000 0111 
0000 1111*
0000 1111*
1000 1111*
1000 1111*
0100 0111 
0100 1111*
0100 1111*
1100 1111*
1100 1111*
Rows in the table for which the interrogator is successful in receiving a reply without collision are marked with the symbol “*”.
In operation, the interrogator transmits a command at a node, requesting that devices within the subgroup represented by the node respond. The interrogator determines if a collision occurs in response to the command and, if not, repeats the command at the same node.
In one alternative embodiment, the upper bound of the number of devices in the field (the maximum possible number of devices that could communicate with the interrogator) is determined, and the tree search method is started at a level 32, 34, 36, 38, or 40 in the tree depending on the determined upper bound. The level of the search tree on which to start the tree search is selected based on the determined maximum possible number of wireless identification devices that could communicate with the interrogator. The tree search is started at a level determined by taking the base two logarithm of the determined maximum possible number. More particularly, the tree search is started at a level determined by taking the base two logarithm of the power of two nearest the determined maximum possible number of devices 12. The level of the tree containing all subgroups of random values is considered level zero, and lower levels are numbered 1, 2, 3, 4, etc. consecutively.
Methods involving determining the upper bound on a set of devices and starting at a level in the tree depending on the determined upper bound are described in a commonly assigned patent application (attorney docket MI40-118) naming Clifton W. Wood, Jr. as an inventor, titled “Method of Addressing Messages and Communications System,” filed concurrently herewith, and incorporated herein by reference.
In one alternative embodiment, a method involving starting at a level in the tree depending on a determined upper bound (such as the method described in the commonly assigned patent application mentioned above) is combined with a method comprising re-trying on the same node that gave a good reply, such as the method shown and described in connection with FIG. 5.
Another arbitration method that can be employed is referred to as the “Aloha” method. In the Aloha method, every time a device 12 is involved in a collision, it waits a random period of time before retransmitting. This method can be improved by dividing time into equally sized slots and forcing transmissions to be aligned with one of these slots. This is referred to as “slotted Aloha.” In operation, the interrogator asks all devices 12 in the field to transmit their identification numbers in the next time slot. If the response is garbled, the interrogator informs the devices 12 that a collision has occurred, and the slotted Aloha scheme is put into action. This means that each device 12 in the field responds within an arbitrary slot determined by a randomly selected value. In other words, in each successive time slot, the devices 12 decide to transmit their identification number with a certain probability.
The Aloha method is based on a system operated by the University of Hawaii. In 1971, the University of Hawaii began operation of a system named Aloha. A communication satellite was used to interconnect several university computers by use of a random access protocol. The system operates as follows. Users or devices transmit at any time they desire. After transmitting, a user listens for an acknowledgment from the receiver or interrogator. Transmissions from different users will sometimes overlap in time (collide), causing reception errors in the data in each of the contending messages. The errors are detected by the receiver, and the receiver sends a negative acknowledgment to the users. When a negative acknowledgment is received, the messages are retransmitted by the colliding users after a random delay. If the colliding users attempted to retransmit without the random delay, they would collide again. If the user does not receive either an acknowledgment or a negative acknowledgment within a certain amount of time, the user “times out” and retransmits the message.
There is a scheme known as slotted Aloha which improves the Aloha scheme by requiring a small amount of coordination among stations. In the slotted Aloha scheme, a sequence of coordination pulses is broadcast to all stations (devices). As is the case with the pure Aloha scheme, packet lengths are constant. Messages are required to be sent in a slot time between synchronization pulses, and can be started only at the beginning of a time slot. This reduces the rate of collisions because only messages transmitted in the same slot can interfere with one another. The retransmission mode of the pure 11 Aloha scheme is modified for slotted Aloha such that if a negative acknowledgment occurs, the device retransmits after a random delay of an integer number of slot times.
Aloha methods are described in a commonly assigned patent application (attorney docket MI40-089) naming Clifton W. Wood, Jr. as an inventor, titled “Method of Addressing Messages and Communications System,” filed concurrently herewith, and incorporated herein by reference.
In one alternative embodiment, an Aloha method (such as the method described in the commonly assigned patent application mentioned above) is combined with a method involving re-trying on the same node that gave a good reply, such as the method shown and described in connection with FIG. 5.
In another embodiment, levels of the search tree are skipped. Skipping levels in the tree, after a collision caused by multiple devices 12 responding, reduces the number of subsequent collisions without adding significantly to the number of no replies. In real-time systems, it is desirable to have quick arbitration sessions on a set of devices 12 whose unique identification numbers are unknown. Level skipping reduces the number of collisions, both reducing arbitration time and conserving battery life on a set of devices 12. In one embodiment, every other level is skipped. In alternative embodiments, more than one level is skipped each time.
The trade off that must be considered in determining how many (if any) levels to skip with each decent down the tree is as follows. Skipping levels reduces the number of collisions, thus saving battery power in the devices 12. Skipping deeper (skipping more than one level) further reduces the number of collisions. The more levels that are skipped, the greater the reduction in collisions. However, skipping levels results in longer search times because the number of queries (Identify commands) increases. The more levels that are skipped, the longer the search times. Skipping just one level has an almost negligible effect on search time, but drastically reduces the number of collisions. If more than one level is skipped, search time increases substantially. Skipping every other level drastically reduces the number of collisions and saves battery power without significantly increasing the number of queries.
Level skipping methods are described in a commonly assigned patent application (attorney docket MI40-117) naming Clifton W. Wood, Jr. and Don Hush as inventors, titled “Method of Addressing Messages, Method of Establishing Wireless Communications, and Communications System,” filed concurrently herewith, and incorporated herein by reference.
In one alternative embodiment, a level skipping method is combined with a method involving re-trying on the same node that gave a good reply, such as the method shown and described in connection with FIG. 5.
In yet another alternative embodiment, any two or more of the methods described in the commonly assigned, concurrently filed, applications mentioned above are combined.
In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.

Claims (60)

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.
2. A method in accordance with claim 1 and further comprising, if a collision occurred in response to the first mentioned command, sending a command at a different node, using the interrogator.
3. A method in accordance with claim 1 wherein when a subgroup contains both a device that is within communications range of the interrogator, and a device that is not within communications range of the interrogator, the device that is not within communications range of the interrogator does not response to the command.
4. A method in accordance with claim 1 wherein when a subgroup contains both a device that is within communications range of the interrogator, and a device that is not within communications range of the interrogator, the device that is within communications range of the interrogator responds to the command.
5. A method in accordance with claim 1 wherein a device in a subgroup changes between being within communications range of the interrogator and not being within communications range, over time.
6. A method in accordance with claim 1 wherein the wireless identification device comprises an integrated circuit including a receiver, a modulator, and a microprocessor in communication with the receiver and modulator.
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;
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.
8. A method of addressing messages from an interrogator to a selected one or more of a number of communications devices in accordance with claim 7 wherein sending a reply to the interrogator comprises transmitting the unique identification number of the device sending the reply.
9. A method in accordance with claim 7 wherein one of the first and second specified groups contains both a device that is within communications range of the interrogator, and a device that is not within communications range of the interrogator, and wherein the device that is not within communications range of the interrogator does not respond to the interrogator.
10. A method of addressing messages from an interrogator to a selected one or more of a number of communications devices in accordance with claim 7 wherein, after receiving a reply without collision from a device, the interrogator sends a communication individually addressed to that device.
11. A method of addressing messages from a transponder to a selected one or more of a number of communications device, the method comprising:
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 command at multiple devices, devices receiving the communication command respectively determining if the random value chosen by the device falls within the specified group and, if so, sending a reply to the transponder interrogator; 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.
12. A method of addressing messages from a transponder to a selected one or more of a number of communications devices in accordance with claim 11 wherein establishing unique identification numbers for respective devices comprises establishing a predetermined number of bits to be used for the unique identification numbers.
13. A method of addressing messages from a transponder to a selected one or more of a number of communications devices in accordance with claim 12 and further including establishing a predetermined number of bits to be used for the random values.
14. 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 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.
15. A method of addressing messages from an interrogator to a selected one or more of a number of RFID devices in accordance with claim 14 wherein the first mentioned specified group contains both a device that is within communications range of the interrogator, and a device that is not within communications range of the interrogator, and wherein the device that is not within communications range of the interrogator does not respond to the transmitting of the command or the re-transmitting of the command.
16. A method of addressing messages from an interrogator to a selected one or more of a number of RFID devices in accordance with claim 14 wherein the first mentioned specified group contains both a device that is within communications range of the interrogator, and a device that is not within communications range of the interrogator, and wherein the device that is within communications range of the interrogator responds to the transmitting of the command and the re-transmitting of the command.
17. A method of addressing messages from an interrogator to a selected one or more of a number of RFID devices in accordance with claim 14 wherein a device in the first mentioned specified group is capable of changing between being within communications range of the interrogator and not being within communications range of the interrogator over time.
18. A method of addressing messages from an interrogator to a selected one or more of a number of RFID devices in accordance with claim 14 wherein the devices respectively comprise an integrated circuit including a receiver, a modulator, and a microprocessor in communication with the receiver and modulator.
19. A method of addressing messages from an interrogator to a selected one or more of a number of RFID devices in accordance with claim 14 and further comprising, after the interrogator transmits a command requesting devices having random values within the new specified group of random values to respond;
devices receiving the command respectively determining if their chosen random values fall within the new smaller specified group and, if so, sending a reply to the interrogator.
20. A method of addressing messages from an interrogator to a selected one or more of a number of RFID devices in accordance with claim 19 and further comprising, after the interrogator transmits a command requesting devices having random values within the new specified group of random values to respond;
determining if a collision occurred between devices that sent a reply and, if so, creating a new specified group and repeating the transmitting of the command requesting devices having random values within a specified group of random values to respond using different specified groups until all of the devices capable of communicating with the interrogator are identified.
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.
22. A communications system in accordance with claim 21 wherein the interrogator is configured to send a command at a different node if a collision occurs in response to the first mentioned command.
23. A communications system in accordance with claim 21 wherein a subgroup contains both a device that is within communications range of the interrogator, and a device that is not within communications range of the interrogator.
24. A communications system in accordance with claim 21 wherein a subgroup contains both a device that is within communications range of the interrogator, and a device that is not within communications range of the interrogator, and wherein the device that is within communications range of the interrogator responds to the command.
25. A communications system in accordance with claim 21 wherein a device in a subgroup is movable relative to the interrogator so as to be capable of changing between being within communications range of the interrogator and not being within communications range.
26. A communications system in accordance with claim 21 wherein the wireless identification device comprises an integrated circuit including a receiver, a modulator, and a microprocessor in communication with the receiver and modulator.
27. A system comprising:
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.
28. A system in accordance with claim 27 wherein sending a reply to the interrogator comprises transmitting the unique identification number of the device sending the reply.
29. A system in accordance with claim 27 wherein a specified group contains both a device that is within communications range of the interrogator, and a device that is not within communications range of the interrogator.
30. A system in accordance with claim 27 wherein the interrogator further includes means for, after receiving a reply without collision from a device, sending a command individually addressed to that device.
31. A system comprising:
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.
32. A system in accordance with claim 31 wherein the first mentioned specified group contains both a device that is within communications range of the interrogator, and a device that is not within communications range of the interrogator.
33. A system in accordance with claim 31 wherein a device in the first mentioned specified group is capable of changing between being within communications range of the interrogator and not being within communications range of the interrogator over time.
34. A system in accordance with claim 31 wherein the respective devices comprise an integrated circuit including a receiver, a modulator, and a microprocessor in communication with the receiver and modulator.
35. 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 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.
36. A system in accordance with claim 35 wherein the unique identification numbers for respective devices are stored in digital form and respectively comprise a predetermined number of bits.
37. A system in accordance with claim 35 wherein the random values for respective devices are stored in digital form and respectively comprise a predetermined number of bits.
38. A system in accordance with claim 35 wherein the interrogator is configured to determine if a collision occurred between devices that sent a reply in response to respective Identify commands and, if so, to create further new specified groups and repeat the transmitting of the command requesting devices having random values within a specified group of random values to respond using different specified groups until all responding devices capable of responding are identified.
39. A method of establishing wireless communications between an interrogator and wireless identification devices, the method comprising:
transmitting a first interrogation command, using the interrogator, to a first plurality of wireless identification devices, said command requesting that devices receiving the command respond to the interrogator;
detecting with the interrogator if a collision occurred in response to the interrogation command;
sending an interrogation command to at least a portion of said first plurality of wireless identification devices until no collision is detected; and
once no collision is detected, sending another interrogation command to at least a portion of said first plurality of wireless identification devices.
40. The method of claim 39, further comprising, after sending said first interrogation command and detecting a collision, sending a signal to at least one wireless identification device configured to avoid a subsequent collision.
41. The method of claim 39, wherein the interrogation command sent to at least a portion of said wireless identification devices after a collision is detected is sent to the entire first plurality of wireless identification devices.
42. The method of claim 39, wherein said interrogation command sent to said first plurality of wireless identification devices is the same interrogation command as is subsequently sent to at least a portion of said wireless identification devices.
43. The method of claim 39, further comprising, after said step of sending an interrogation command after no collision is detected, sending a communication to a selected wireless identification device through use of an identification individually addressed to that device.
44. A method of establishing wireless communications between an interrogator and wireless identification devices, the method comprising:
transmitting a first interrogation command, using the interrogator, to a first plurality of wireless identification devices, said command requesting that devices receiving the command respond to the interrogator;
detecting if a collision occurred in response to the interrogation command;
in the event of detection of a collision, sending a signal to at least one wireless identification device to avoid a subsequent collision;
sending an interrogation command to at least a portion of said first plurality of wireless identification devices until no collision is detected; and
once no collision is detected, sending another interrogation command to said first plurality of wireless identification devices.
45. A method comprising:
performing arbitration including sending a first command from an interrogator to a plurality of wireless identification devices;
receiving a good reply from a first wireless identification device of the plurality of wireless identification devices in response to the first command;
sending a second command from the interrogator to silence the first wireless identification device; and
resending the first command from the interrogator to the plurality of wireless identification devices.
46. The method of claim 45 wherein performing the arbitration is done using a search tree.
47. The method of claim 46 wherein the first command requests a response from wireless identification devices associated with a first node of the search tree.
48. The method of claim 45 wherein the second command individually addresses the first wireless identification device.
49. The method of claim 45 wherein the good reply comprises unique ID received by the interrogator without a collision detected.
50. An arbitration method comprising:
sending a first command from an interrogator to a plurality of wireless identification devices;
receiving a reply from a first wireless identification device of the plurality of wireless identification devices, and detecting no collisions, in response to the first command; and
resending the first command from the interrogator to the plurality of wireless identification devices in response to receiving the reply and detecting no collisions.
51. The method of claim 50, further comprising sending a second command from the interrogator to silence the first wireless identification device, in response to receiving the reply, before resending the first command.
52. The method of claim 51, wherein sending the second command comprises sending a number associated with the first wireless identification device to address the first wireless identification device.
53. The method of claim 50, further comprising:
sending a third command from the interrogator to the plurality of wireless identification devices;
receiving a reply from a second wireless identification device of the plurality of wireless identification devices, and detecting no collisions, in response to the third command; and
resending the third command from the interrogator to the plurality of wireless identification devices in response to receiving the reply from the second wireless identification device and detecting no collisions.
54. The method of claim 50, wherein sending the first command comprises sending a request for identification, the request including at least a portion of a number that identifies the first wireless identification.
55. The method of claim 54, wherein the portion of the number is associated with a node of a search tree.
56. The method of claim 50, wherein receiving the reply includes receiving the reply at a randomly selected time.
57. The method of claim 56, wherein receiving the reply at a randomly selected time is in accordance with an Aloha method.
58. The method of claim 57, wherein the Aloha method is a slotted Aloha method.
59. The method of claim 50, wherein sending the first command comprises sending a request for identification, the request including a number associated with a node of a search tree, and wherein receiving the reply is in accordance with an Aloha method.
60. The method of claim 50, wherein receiving the reply comprises receiving at least a portion of a number that identifies the first wireless identification device.
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US11/862,124 USRE41352E1 (en) 1998-02-19 2007-09-26 Method of addressing messages and communications
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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090322491A1 (en) * 1998-02-19 2009-12-31 Keystone Technology Solutions, Llc Method of Addressing Messages and Communications System
US20110116421A1 (en) * 2009-09-25 2011-05-19 Dongning Guo Rapid on-off-division duplex network communications
USRE42599E1 (en) 1998-02-19 2011-08-09 Round Rock Research, Llc Method of addressing messages and communications system
USRE43254E1 (en) 1998-02-19 2012-03-20 Round Rock Research, Llc Method of addressing messages and communications systems
USRE43382E1 (en) 1998-02-19 2012-05-15 Round Rock Research, Llc Method of addressing messages and communications systems
USRE44411E1 (en) 1998-02-19 2013-08-06 Round Rock Research, Llc Method of addressing messages, method of establishing wireless communications and communications system
US8645222B1 (en) 2009-03-20 2014-02-04 Jpmorgan Chase Bank, N.A. System and methods for mobile ordering and payment
US9832769B2 (en) 2009-09-25 2017-11-28 Northwestern University Virtual full duplex network communications

Families Citing this family (88)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8538801B2 (en) 1999-02-19 2013-09-17 Exxonmobile Research & Engineering Company System and method for processing financial transactions
US6739487B2 (en) * 1999-03-01 2004-05-25 Thule Sweden Ab Vertically engageable carrier foot
US6323771B1 (en) * 1999-04-09 2001-11-27 James S. Payne Method of identifying animals via universal identification scheme
US7005985B1 (en) * 1999-07-20 2006-02-28 Axcess, Inc. Radio frequency identification system and method
US7239226B2 (en) 2001-07-10 2007-07-03 American Express Travel Related Services Company, Inc. System and method for payment using radio frequency identification in contact and contactless transactions
US7889052B2 (en) * 2001-07-10 2011-02-15 Xatra Fund Mx, Llc Authorizing payment subsequent to RF transactions
US8543423B2 (en) * 2002-07-16 2013-09-24 American Express Travel Related Services Company, Inc. Method and apparatus for enrolling with multiple transaction environments
US8429041B2 (en) 2003-05-09 2013-04-23 American Express Travel Related Services Company, Inc. Systems and methods for managing account information lifecycles
WO2001067355A2 (en) 2000-03-07 2001-09-13 American Express Travel Related Services Company, Inc. System for facilitating a transaction
US7650314B1 (en) 2001-05-25 2010-01-19 American Express Travel Related Services Company, Inc. System and method for securing a recurrent billing transaction
US7542942B2 (en) * 2001-07-10 2009-06-02 American Express Travel Related Services Company, Inc. System and method for securing sensitive information during completion of a transaction
US6988667B2 (en) * 2001-05-31 2006-01-24 Alien Technology Corporation Methods and apparatuses to identify devices
US9031880B2 (en) 2001-07-10 2015-05-12 Iii Holdings 1, Llc Systems and methods for non-traditional payment using biometric data
US7668750B2 (en) 2001-07-10 2010-02-23 David S Bonalle Securing RF transactions using a transactions counter
US7996324B2 (en) 2001-07-10 2011-08-09 American Express Travel Related Services Company, Inc. Systems and methods for managing multiple accounts on a RF transaction device using secondary identification indicia
US7762457B2 (en) 2001-07-10 2010-07-27 American Express Travel Related Services Company, Inc. System and method for dynamic fob synchronization and personalization
US8294552B2 (en) 2001-07-10 2012-10-23 Xatra Fund Mx, Llc Facial scan biometrics on a payment device
US9454752B2 (en) 2001-07-10 2016-09-27 Chartoleaux Kg Limited Liability Company Reload protocol at a transaction processing entity
US7805378B2 (en) 2001-07-10 2010-09-28 American Express Travel Related Servicex Company, Inc. System and method for encoding information in magnetic stripe format for use in radio frequency identification transactions
US7303120B2 (en) 2001-07-10 2007-12-04 American Express Travel Related Services Company, Inc. System for biometric security using a FOB
US8001054B1 (en) 2001-07-10 2011-08-16 American Express Travel Related Services Company, Inc. System and method for generating an unpredictable number using a seeded algorithm
US8960535B2 (en) * 2001-07-10 2015-02-24 Iii Holdings 1, Llc Method and system for resource management and evaluation
US8548927B2 (en) 2001-07-10 2013-10-01 Xatra Fund Mx, Llc Biometric registration for facilitating an RF transaction
US7249112B2 (en) 2002-07-09 2007-07-24 American Express Travel Related Services Company, Inc. System and method for assigning a funding source for a radio frequency identification device
US7925535B2 (en) * 2001-07-10 2011-04-12 American Express Travel Related Services Company, Inc. System and method for securing RF transactions using a radio frequency identification device including a random number generator
US7503480B2 (en) * 2001-07-10 2009-03-17 American Express Travel Related Services Company, Inc. Method and system for tracking user performance
US7735725B1 (en) 2001-07-10 2010-06-15 Fred Bishop Processing an RF transaction using a routing number
US20040236699A1 (en) 2001-07-10 2004-11-25 American Express Travel Related Services Company, Inc. Method and system for hand geometry recognition biometrics on a fob
US9024719B1 (en) 2001-07-10 2015-05-05 Xatra Fund Mx, Llc RF transaction system and method for storing user personal data
US8279042B2 (en) * 2001-07-10 2012-10-02 Xatra Fund Mx, Llc Iris scan biometrics on a payment device
US7360689B2 (en) 2001-07-10 2008-04-22 American Express Travel Related Services Company, Inc. Method and system for proffering multiple biometrics for use with a FOB
US7746215B1 (en) 2001-07-10 2010-06-29 Fred Bishop RF transactions using a wireless reader grid
US8635131B1 (en) 2001-07-10 2014-01-21 American Express Travel Related Services Company, Inc. System and method for managing a transaction protocol
US7193504B2 (en) * 2001-10-09 2007-03-20 Alien Technology Corporation Methods and apparatuses for identification
DE60221700T2 (en) * 2001-12-11 2008-04-30 Tagsys S.A. SYSTEMS FOR SAFELY MARKING DATA
US6972682B2 (en) * 2002-01-18 2005-12-06 Georgia Tech Research Corporation Monitoring and tracking of assets by utilizing wireless communications
US20040046642A1 (en) * 2002-09-05 2004-03-11 Honeywell International Inc. Protocol for addressing groups of RFID tags
US6805287B2 (en) 2002-09-12 2004-10-19 American Express Travel Related Services Company, Inc. System and method for converting a stored value card to a credit card
US7009526B2 (en) * 2002-10-02 2006-03-07 Battelle Memorial Institute RFID system and method including tag ID compression
US7515882B2 (en) * 2002-12-17 2009-04-07 Kelcourse Mark F Apparatus, methods and articles of manufacture for a multi-band switch
US7869770B2 (en) * 2002-12-17 2011-01-11 M/A-Com Technology Solutions Holdings, Inc. Apparatus, methods and articles of manufacture for a multi-band switch
JP2004259123A (en) * 2003-02-27 2004-09-16 Nec Micro Systems Ltd Rfid (radio frequency identification) system and program for rfid
US6970070B2 (en) * 2003-05-08 2005-11-29 Rsa Security Inc. Method and apparatus for selective blocking of radio frequency identification devices
FR2857475B1 (en) * 2003-07-10 2007-02-02 Commissariat Energie Atomique DEVICE COMPRISING A MATRIX OF MICROSYSTEMS ADDRESSABLE INDIVIDUALLY BY ELECTROMAGNETIC TRANSMISSION AND METHOD OF ADDRESSING SUCH A DEVICE
US8102244B2 (en) * 2003-08-09 2012-01-24 Alien Technology Corporation Methods and apparatuses to identify devices
US7119664B2 (en) * 2003-09-17 2006-10-10 Id Solutions, Inc. Deep sleep in an RFID tag
US7716160B2 (en) * 2003-11-07 2010-05-11 Alien Technology Corporation Methods and apparatuses to identify devices
US7880589B2 (en) * 2004-02-06 2011-02-01 Battelle Memorial Institute Communications device identification methods, communications methods, wireless communications readers, wireless communications systems, and articles of manufacture
US7841120B2 (en) 2004-03-22 2010-11-30 Wilcox Industries Corp. Hand grip apparatus for firearm
US20050237159A1 (en) * 2004-04-13 2005-10-27 Impinj, Inc. RFID tag systems, RFID tags and RFID processes with reverse link burst mode
US20050237158A1 (en) * 2004-04-13 2005-10-27 Impinj, Inc. RFID tag systems, RFID tags and RFID processes using N-ary FSK
US20050237157A1 (en) * 2004-04-13 2005-10-27 Impinj, Inc. RFID tag systems, RFID tags and RFID processes with branch node indexing
DE102004018540A1 (en) * 2004-04-14 2005-11-03 Atmel Germany Gmbh Method for selecting one or more transponders
DE102004018541A1 (en) * 2004-04-14 2005-11-17 Atmel Germany Gmbh Method for selecting one or more transponders
US7318550B2 (en) 2004-07-01 2008-01-15 American Express Travel Related Services Company, Inc. Biometric safeguard method for use with a smartcard
US8604910B2 (en) * 2004-07-13 2013-12-10 Cisco Technology, Inc. Using syslog and SNMP for scalable monitoring of networked devices
JP2008507043A (en) * 2004-07-15 2008-03-06 マスターカード インターナシヨナル インコーポレーテツド Contactless payment card reader with frustoconical operating volume
WO2006015145A2 (en) * 2004-07-29 2006-02-09 Rsa Security Inc. Methods and apparatus for rfid device authentication
US7920050B2 (en) * 2004-07-29 2011-04-05 Emc Corporation Proxy device for enhanced privacy in an RFID system
US7581678B2 (en) 2005-02-22 2009-09-01 Tyfone, Inc. Electronic transaction card
WO2006133087A2 (en) * 2005-06-03 2006-12-14 Ems Technologies, Inc. Method and system for discovering antenna line devices
US7953826B2 (en) 2005-07-14 2011-05-31 Cisco Technology, Inc. Provisioning and redundancy for RFID middleware servers
KR100693006B1 (en) * 2005-07-26 2007-03-12 삼성전자주식회사 ID anti-collision method using data structure to be applied to RFID system
KR100625675B1 (en) * 2005-09-30 2006-09-18 에스케이 텔레콤주식회사 Method for identifying tags using adaptive binary tree splitting technique in rfid system and rfid system therefor
WO2007049219A2 (en) * 2005-10-25 2007-05-03 Nxp B.V. Method of reading data from transponders through a reader, a transponder, and a reader
US8698603B2 (en) * 2005-11-15 2014-04-15 Cisco Technology, Inc. Methods and systems for automatic device provisioning in an RFID network using IP multicast
US8378786B2 (en) * 2006-02-03 2013-02-19 Emc Corporation Security provision in standards-compliant RFID systems
US20070205896A1 (en) * 2006-03-02 2007-09-06 Axcess International Inc. System and Method for Determining Location, Directionality, and Velocity of RFID Tags
WO2007109241A2 (en) * 2006-03-20 2007-09-27 Axcess International Inc. Multi-tag tracking systems and methods
WO2007133690A2 (en) * 2006-05-11 2007-11-22 Axcess International Inc. Radio frequency identification (rfid) tag antenna design
WO2008062331A2 (en) * 2006-11-23 2008-05-29 International Business Machines Corporation Privacy method, device and computer program
US7924141B2 (en) * 2006-12-01 2011-04-12 Round Rock Research, Llc RFID communication systems and methods, and RFID readers and systems
US8181879B2 (en) 2006-12-29 2012-05-22 Solicore, Inc. Mailing apparatus for powered cards
US7967214B2 (en) 2006-12-29 2011-06-28 Solicore, Inc. Card configured to receive separate battery
US7973644B2 (en) 2007-01-30 2011-07-05 Round Rock Research, Llc Systems and methods for RFID tag arbitration where RFID tags generate multiple random numbers for different arbitration sessions
US8134452B2 (en) * 2007-05-30 2012-03-13 Round Rock Research, Llc Methods and systems of receiving data payload of RFID tags
CN101430753B (en) * 2007-11-08 2011-01-19 中兴通讯股份有限公司 Label anti-collision method for radio frequency recognition system
US9741027B2 (en) 2007-12-14 2017-08-22 Tyfone, Inc. Memory card based contactless devices
US8638194B2 (en) * 2008-07-25 2014-01-28 Axcess International, Inc. Multiple radio frequency identification (RFID) tag wireless wide area network (WWAN) protocol
US20100033310A1 (en) * 2008-08-08 2010-02-11 Narendra Siva G Power negotation for small rfid card
US8451122B2 (en) 2008-08-08 2013-05-28 Tyfone, Inc. Smartcard performance enhancement circuits and systems
US7961101B2 (en) 2008-08-08 2011-06-14 Tyfone, Inc. Small RFID card with integrated inductive element
US8231061B2 (en) 2009-02-24 2012-07-31 Tyfone, Inc Contactless device with miniaturized antenna
CN101860948B (en) 2009-04-13 2014-07-30 华为技术有限公司 Method, equipment and system for regulating power consumption
US9734645B2 (en) 2010-10-15 2017-08-15 The Chamberlain Group, Inc. Method and apparatus pertaining to message-based functionality
US9160906B2 (en) 2011-02-03 2015-10-13 Jason R. Bond Head-mounted face image capturing devices and systems
US8573866B2 (en) * 2011-02-03 2013-11-05 Jason R. Bond Head-mounted face image capturing devices and systems
RU2657185C1 (en) 2017-09-13 2018-06-08 Самсунг Электроникс Ко., Лтд. High frequency local positioning system

Citations (65)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4075632A (en) 1974-08-27 1978-02-21 The United States Of America As Represented By The United States Department Of Energy Interrogation, and detection system
US4761778A (en) 1985-04-11 1988-08-02 Massachusetts Institute Of Technology Coder-packetizer for random accessing in digital communication with multiple accessing
US4799059A (en) 1986-03-14 1989-01-17 Enscan, Inc. Automatic/remote RF instrument monitoring system
US4845504A (en) 1987-04-08 1989-07-04 M/A-Com, Inc. Mobile radio network for nationwide communications
US4862453A (en) 1986-10-03 1989-08-29 The Marconi Company Limited Communication system
US4926182A (en) 1986-05-30 1990-05-15 Sharp Kabushiki Kaisha Microwave data transmission apparatus
US4955018A (en) 1987-11-10 1990-09-04 Echelon Systems Corporation Protocol for network having plurality of intelligent cells
US4969146A (en) 1987-11-10 1990-11-06 Echelon Systems Corporation Protocol for network having a plurality of intelligent cells
US5019813A (en) 1987-04-13 1991-05-28 N.V. Nederlandsche Apparatenfabriek Nedap System for the contactless exchange of data
US5025486A (en) 1988-12-09 1991-06-18 Dallas Semiconductor Corporation Wireless communication system with parallel polling
US5046066A (en) 1987-02-09 1991-09-03 Telesystems Slw Inc. Wireless local area network
US5055968A (en) 1988-07-04 1991-10-08 Sony Corporation Thin electronic device having an integrated circuit chip and a power battery and a method for producing same
US5121407A (en) 1990-09-27 1992-06-09 Pittway Corporation Spread spectrum communications system
US5124697A (en) 1989-10-16 1992-06-23 Motorola, Inc. Acknowledge-back pager
US5142694A (en) 1989-07-24 1992-08-25 Motorola, Inc. Reporting unit
US5144668A (en) 1991-01-25 1992-09-01 Motorola, Inc. Signal overlap detection in a communication system
US5144313A (en) 1988-10-27 1992-09-01 Steffen Kirknes Method for processing transmitted and reflected signals for removing unwanted signals and noise from wanted signals
US5150310A (en) 1989-08-30 1992-09-22 Consolve, Inc. Method and apparatus for position detection
US5150114A (en) 1989-11-10 1992-09-22 U.S. Philips Corporation Polling-type information transmission system
US5164985A (en) 1987-10-27 1992-11-17 Nysen Paul A Passive universal communicator system
US5168510A (en) 1984-03-06 1992-12-01 Comsource Systems Spread spectrum-time diversity communications systems and transceivers for multidrop area networks
US5194860A (en) 1989-11-16 1993-03-16 The General Electric Company, P.L.C. Radio telemetry systems with channel selection
US5231646A (en) 1992-03-16 1993-07-27 Kyros Corporation Communications system
US5266925A (en) 1991-09-30 1993-11-30 Westinghouse Electric Corp. Electronic identification tag interrogation method
US5307463A (en) 1990-03-08 1994-04-26 Allen-Bradley Company, Inc. Programmable controller communication module
US5365551A (en) 1992-12-15 1994-11-15 Micron Technology, Inc. Data communication transceiver using identification protocol
US5373503A (en) 1993-04-30 1994-12-13 Information Technology, Inc. Group randomly addressed polling method
US5479416A (en) 1993-09-30 1995-12-26 Micron Technology, Inc. Apparatus and method for error detection and correction in radio frequency identification device
US5500650A (en) 1992-12-15 1996-03-19 Micron Technology, Inc. Data communication method using identification protocol
US5619648A (en) 1994-11-30 1997-04-08 Lucent Technologies Inc. Message filtering techniques
US5621412A (en) 1994-04-26 1997-04-15 Texas Instruments Incorporated Multi-stage transponder wake-up, method and structure
US5625628A (en) 1995-03-15 1997-04-29 Hughes Electronics Aloha optimization
US5640151A (en) 1990-06-15 1997-06-17 Texas Instruments Incorporated Communication system for communicating with tags
EP0779520A2 (en) 1995-12-12 1997-06-18 AT&T Corp. Enhanced uplink modulated backscatter system
US5649296A (en) 1995-06-19 1997-07-15 Lucent Technologies Inc. Full duplex modulated backscatter system
WO1997048216A2 (en) 1996-06-10 1997-12-18 At & T Wireless Services, Inc. Registration of mobile packet data terminals after disaster
US5790946A (en) 1993-07-15 1998-08-04 Rotzoll; Robert R. Wake up device for a communications system
US5805586A (en) 1995-05-02 1998-09-08 Motorola Inc. Method, device and data communication system for multilink polling
US5914671A (en) 1997-02-27 1999-06-22 Micron Communications, Inc. System and method for locating individuals and equipment, airline reservation system, communication system
US5936560A (en) 1996-12-04 1999-08-10 Fujitsu Limited Data compression method and apparatus performing high-speed comparison between data stored in a dictionary window and data to be compressed
US5942987A (en) 1994-09-09 1999-08-24 Intermec Ip Corp. Radio frequency identification system with write broadcast capability
US5952922A (en) 1996-12-31 1999-09-14 Lucent Technologies Inc. In-building modulated backscatter system
US5966471A (en) 1997-12-23 1999-10-12 United States Of America Method of codebook generation for an amplitude-adaptive vector quantization system
US5974078A (en) 1993-03-17 1999-10-26 Micron Technology, Inc. Modulated spread spectrum in RF identification systems method
US5988510A (en) 1997-02-13 1999-11-23 Micron Communications, Inc. Tamper resistant smart card and method of protecting data in a smart card
US6038455A (en) 1995-09-25 2000-03-14 Cirrus Logic, Inc. Reverse channel reuse scheme in a time shared cellular communication system
US6061344A (en) 1998-02-19 2000-05-09 Micron Technology, Inc. Method of addressing messages and communications system
US6072801A (en) 1998-02-19 2000-06-06 Micron Technology, Inc. Method of addressing messages, method of establishing wireless communications, and communications system
US6075973A (en) 1998-05-18 2000-06-13 Micron Technology, Inc. Method of communications in a backscatter system, interrogator, and backscatter communications system
US6104333A (en) 1996-12-19 2000-08-15 Micron Technology, Inc. Methods of processing wireless communication, methods of processing radio frequency communication, and related systems
US6118789A (en) 1998-02-19 2000-09-12 Micron Technology, Inc. Method of addressing messages and communications system
US6130602A (en) 1996-05-13 2000-10-10 Micron Technology, Inc. Radio frequency data communications device
US6169474B1 (en) 1998-04-23 2001-01-02 Micron Technology, Inc. Method of communications in a backscatter system, interrogator, and backscatter communications system
US6192222B1 (en) 1998-09-03 2001-02-20 Micron Technology, Inc. Backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods
US6216132B1 (en) 1997-11-20 2001-04-10 International Business Machines Corporation Method and system for matching consumers to events
US6275476B1 (en) 1998-02-19 2001-08-14 Micron Technology, Inc. Method of addressing messages and communications system
US6289209B1 (en) 1996-12-18 2001-09-11 Micron Technology, Inc. Wireless communication system, radio frequency communications system, wireless communications method, radio frequency communications method
US6324211B1 (en) 1998-04-24 2001-11-27 Micron Technology, Inc. Interrogators communication systems communication methods and methods of processing a communication signal
US6459726B1 (en) 1998-04-24 2002-10-01 Micron Technology, Inc. Backscatter interrogators, communication systems and backscatter communication methods
US6566997B1 (en) 1999-12-03 2003-05-20 Hid Corporation Interference control method for RFID systems
US6707376B1 (en) 2002-08-09 2004-03-16 Sensormatic Electronics Corporation Pulsed power method for increased read range for a radio frequency identification reader
US6714559B1 (en) * 1991-12-04 2004-03-30 Broadcom Corporation Redundant radio frequency network having a roaming terminal communication protocol
US6850510B2 (en) * 1995-10-05 2005-02-01 Broadcom Corporation Hierarchical data collection network supporting packetized voice communications among wireless terminals and telephones
US20060022801A1 (en) 2004-07-30 2006-02-02 Reva Systems Corporation RFID tag data acquisition system
US7026935B2 (en) 2003-11-10 2006-04-11 Impinj, Inc. Method and apparatus to configure an RFID system to be adaptable to a plurality of environmental conditions

Family Cites Families (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4796023A (en) * 1986-12-05 1989-01-03 King Robert E Stabilized binary tree protocol
US5461627A (en) 1991-12-24 1995-10-24 Rypinski; Chandos A. Access protocol for a common channel wireless network
US5449296A (en) * 1994-03-07 1995-09-12 Cabel-Con, Inc. Usa Cable connector apparatus for preventing radiation leakage
US5530702A (en) 1994-05-31 1996-06-25 Ludwig Kipp System for storage and communication of information
US6812852B1 (en) 1994-09-09 2004-11-02 Intermac Ip Corp. System and method for selecting a subset of autonomous and independent slave entities
US5550547A (en) 1994-09-12 1996-08-27 International Business Machines Corporation Multiple item radio frequency tag identification protocol
US7085637B2 (en) 1997-10-22 2006-08-01 Intelligent Technologies International, Inc. Method and system for controlling a vehicle
FR2741979B1 (en) 1995-12-01 1998-01-23 Raimbault Pierre METHOD FOR REMOTE QUERYING STATION LABELS AND LABEL FOR IMPLEMENTING SAME
US6097292A (en) 1997-04-01 2000-08-01 Cubic Corporation Contactless proximity automated data collection system and method
US6812824B1 (en) * 1996-10-17 2004-11-02 Rf Technologies, Inc. Method and apparatus combining a tracking system and a wireless communication system
CA2268951A1 (en) 1996-10-17 1998-04-23 Pinpoint Corporation Article tracking system
US6107910A (en) * 1996-11-29 2000-08-22 X-Cyte, Inc. Dual mode transmitter/receiver and decoder for RF transponder tags
US6243012B1 (en) 1996-12-31 2001-06-05 Lucent Technologies Inc. Inexpensive modulated backscatter reflector
US6130623A (en) 1996-12-31 2000-10-10 Lucent Technologies Inc. Encryption for modulated backscatter systems
US6570487B1 (en) * 1997-01-24 2003-05-27 Axcess Inc. Distributed tag reader system and method
US6415439B1 (en) 1997-02-04 2002-07-02 Microsoft Corporation Protocol for a wireless control system
US6288629B1 (en) 1997-05-23 2001-09-11 Intermec Ip Corp. Method of using write—ok flag for radio frequency (RF) transponders (RF Tags)
US6078888A (en) 1997-07-16 2000-06-20 Gilbarco Inc. Cryptography security for remote dispenser transactions
US5986570A (en) 1997-09-03 1999-11-16 Micron Communications, Inc. Method for resolving signal collisions between multiple RFID transponders in a field
GB9724183D0 (en) * 1997-11-14 1998-01-14 British Tech Group Identification system
US6778096B1 (en) 1997-11-17 2004-08-17 International Business Machines Corporation Method and apparatus for deploying and tracking computers
JP3690285B2 (en) 2001-02-01 2005-08-31 日本ビクター株式会社 Color separation / synthesis optical system and projection display device using the same
US7688764B2 (en) 2002-06-20 2010-03-30 Motorola, Inc. Method and apparatus for speaker arbitration in a multi-participant communication session
US20080007421A1 (en) 2005-08-02 2008-01-10 University Of Houston Measurement-while-drilling (mwd) telemetry by wireless mems radio units
US7924141B2 (en) 2006-12-01 2011-04-12 Round Rock Research, Llc RFID communication systems and methods, and RFID readers and systems
US7973644B2 (en) 2007-01-30 2011-07-05 Round Rock Research, Llc Systems and methods for RFID tag arbitration where RFID tags generate multiple random numbers for different arbitration sessions

Patent Citations (79)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4075632A (en) 1974-08-27 1978-02-21 The United States Of America As Represented By The United States Department Of Energy Interrogation, and detection system
US5168510A (en) 1984-03-06 1992-12-01 Comsource Systems Spread spectrum-time diversity communications systems and transceivers for multidrop area networks
US4761778A (en) 1985-04-11 1988-08-02 Massachusetts Institute Of Technology Coder-packetizer for random accessing in digital communication with multiple accessing
US4799059A (en) 1986-03-14 1989-01-17 Enscan, Inc. Automatic/remote RF instrument monitoring system
US4926182A (en) 1986-05-30 1990-05-15 Sharp Kabushiki Kaisha Microwave data transmission apparatus
US4862453A (en) 1986-10-03 1989-08-29 The Marconi Company Limited Communication system
US5046066A (en) 1987-02-09 1991-09-03 Telesystems Slw Inc. Wireless local area network
US4845504A (en) 1987-04-08 1989-07-04 M/A-Com, Inc. Mobile radio network for nationwide communications
US5019813A (en) 1987-04-13 1991-05-28 N.V. Nederlandsche Apparatenfabriek Nedap System for the contactless exchange of data
US5164985A (en) 1987-10-27 1992-11-17 Nysen Paul A Passive universal communicator system
US4969146A (en) 1987-11-10 1990-11-06 Echelon Systems Corporation Protocol for network having a plurality of intelligent cells
US4955018A (en) 1987-11-10 1990-09-04 Echelon Systems Corporation Protocol for network having plurality of intelligent cells
US5055968A (en) 1988-07-04 1991-10-08 Sony Corporation Thin electronic device having an integrated circuit chip and a power battery and a method for producing same
US5144313A (en) 1988-10-27 1992-09-01 Steffen Kirknes Method for processing transmitted and reflected signals for removing unwanted signals and noise from wanted signals
US5025486A (en) 1988-12-09 1991-06-18 Dallas Semiconductor Corporation Wireless communication system with parallel polling
US5142694A (en) 1989-07-24 1992-08-25 Motorola, Inc. Reporting unit
US5150310A (en) 1989-08-30 1992-09-22 Consolve, Inc. Method and apparatus for position detection
US5124697A (en) 1989-10-16 1992-06-23 Motorola, Inc. Acknowledge-back pager
US5150114A (en) 1989-11-10 1992-09-22 U.S. Philips Corporation Polling-type information transmission system
US5194860A (en) 1989-11-16 1993-03-16 The General Electric Company, P.L.C. Radio telemetry systems with channel selection
US5307463A (en) 1990-03-08 1994-04-26 Allen-Bradley Company, Inc. Programmable controller communication module
US5640151A (en) 1990-06-15 1997-06-17 Texas Instruments Incorporated Communication system for communicating with tags
US5121407A (en) 1990-09-27 1992-06-09 Pittway Corporation Spread spectrum communications system
US5144668A (en) 1991-01-25 1992-09-01 Motorola, Inc. Signal overlap detection in a communication system
US5266925A (en) 1991-09-30 1993-11-30 Westinghouse Electric Corp. Electronic identification tag interrogation method
US6714559B1 (en) * 1991-12-04 2004-03-30 Broadcom Corporation Redundant radio frequency network having a roaming terminal communication protocol
US5231646A (en) 1992-03-16 1993-07-27 Kyros Corporation Communications system
US5841770A (en) 1992-12-15 1998-11-24 Micron Technology, Inc. Data communication system using indentification protocol
US5500650A (en) 1992-12-15 1996-03-19 Micron Technology, Inc. Data communication method using identification protocol
US5583850A (en) 1992-12-15 1996-12-10 Micron Technology, Inc. Data communication system using identification protocol
US5627544A (en) 1992-12-15 1997-05-06 Micron Technology, Inc. Data communication method using identification protocol
US5365551A (en) 1992-12-15 1994-11-15 Micron Technology, Inc. Data communication transceiver using identification protocol
US5974078A (en) 1993-03-17 1999-10-26 Micron Technology, Inc. Modulated spread spectrum in RF identification systems method
US5373503A (en) 1993-04-30 1994-12-13 Information Technology, Inc. Group randomly addressed polling method
US5790946A (en) 1993-07-15 1998-08-04 Rotzoll; Robert R. Wake up device for a communications system
US5608739A (en) 1993-09-30 1997-03-04 Micron Technology, Inc. Apparatus and method for error detection and correction in radio frequency identification device
US5479416A (en) 1993-09-30 1995-12-26 Micron Technology, Inc. Apparatus and method for error detection and correction in radio frequency identification device
US5621412A (en) 1994-04-26 1997-04-15 Texas Instruments Incorporated Multi-stage transponder wake-up, method and structure
US5942987A (en) 1994-09-09 1999-08-24 Intermec Ip Corp. Radio frequency identification system with write broadcast capability
US5619648A (en) 1994-11-30 1997-04-08 Lucent Technologies Inc. Message filtering techniques
US5625628A (en) 1995-03-15 1997-04-29 Hughes Electronics Aloha optimization
US5805586A (en) 1995-05-02 1998-09-08 Motorola Inc. Method, device and data communication system for multilink polling
US5649296A (en) 1995-06-19 1997-07-15 Lucent Technologies Inc. Full duplex modulated backscatter system
US6038455A (en) 1995-09-25 2000-03-14 Cirrus Logic, Inc. Reverse channel reuse scheme in a time shared cellular communication system
US6850510B2 (en) * 1995-10-05 2005-02-01 Broadcom Corporation Hierarchical data collection network supporting packetized voice communications among wireless terminals and telephones
US5940006A (en) 1995-12-12 1999-08-17 Lucent Technologies Inc. Enhanced uplink modulated backscatter system
EP0779520A2 (en) 1995-12-12 1997-06-18 AT&T Corp. Enhanced uplink modulated backscatter system
US6130602A (en) 1996-05-13 2000-10-10 Micron Technology, Inc. Radio frequency data communications device
US6771634B1 (en) 1996-06-10 2004-08-03 At&T Wireless Services, Inc. Registration of mobile packet data terminals after disaster
US6157633A (en) 1996-06-10 2000-12-05 At&T Wireless Sucs. Inc. Registration of mobile packet data terminals after disaster
WO1997048216A2 (en) 1996-06-10 1997-12-18 At & T Wireless Services, Inc. Registration of mobile packet data terminals after disaster
US5936560A (en) 1996-12-04 1999-08-10 Fujitsu Limited Data compression method and apparatus performing high-speed comparison between data stored in a dictionary window and data to be compressed
US6289209B1 (en) 1996-12-18 2001-09-11 Micron Technology, Inc. Wireless communication system, radio frequency communications system, wireless communications method, radio frequency communications method
US6104333A (en) 1996-12-19 2000-08-15 Micron Technology, Inc. Methods of processing wireless communication, methods of processing radio frequency communication, and related systems
US6265963B1 (en) 1996-12-19 2001-07-24 Micron Technology, Inc. Methods of processing wireless communication, methods of processing radio frequency communication, and related systems
US5952922A (en) 1996-12-31 1999-09-14 Lucent Technologies Inc. In-building modulated backscatter system
US5988510A (en) 1997-02-13 1999-11-23 Micron Communications, Inc. Tamper resistant smart card and method of protecting data in a smart card
US5914671A (en) 1997-02-27 1999-06-22 Micron Communications, Inc. System and method for locating individuals and equipment, airline reservation system, communication system
US6216132B1 (en) 1997-11-20 2001-04-10 International Business Machines Corporation Method and system for matching consumers to events
US5966471A (en) 1997-12-23 1999-10-12 United States Of America Method of codebook generation for an amplitude-adaptive vector quantization system
US6226300B1 (en) 1998-02-19 2001-05-01 Micron Technology, Inc. Method of addressing messages, and establishing communications using a tree search technique that skips levels
US6072801A (en) 1998-02-19 2000-06-06 Micron Technology, Inc. Method of addressing messages, method of establishing wireless communications, and communications system
US6061344A (en) 1998-02-19 2000-05-09 Micron Technology, Inc. Method of addressing messages and communications system
US6307848B1 (en) 1998-02-19 2001-10-23 Micron Technology, Inc. Method of addressing messages, method of establishing wireless communications, and communications system
US6275476B1 (en) 1998-02-19 2001-08-14 Micron Technology, Inc. Method of addressing messages and communications system
US6282186B1 (en) 1998-02-19 2001-08-28 Micron Technology, Inc. Method of addressing messages and communications system
US6118789A (en) 1998-02-19 2000-09-12 Micron Technology, Inc. Method of addressing messages and communications system
US6169474B1 (en) 1998-04-23 2001-01-02 Micron Technology, Inc. Method of communications in a backscatter system, interrogator, and backscatter communications system
US6324211B1 (en) 1998-04-24 2001-11-27 Micron Technology, Inc. Interrogators communication systems communication methods and methods of processing a communication signal
US6459726B1 (en) 1998-04-24 2002-10-01 Micron Technology, Inc. Backscatter interrogators, communication systems and backscatter communication methods
US6075973A (en) 1998-05-18 2000-06-13 Micron Technology, Inc. Method of communications in a backscatter system, interrogator, and backscatter communications system
US6229987B1 (en) 1998-05-18 2001-05-08 Micron Technology, Inc. Method of communications in a backscatter system, interrogator, and backscatter communications system
US6192222B1 (en) 1998-09-03 2001-02-20 Micron Technology, Inc. Backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods
US6566997B1 (en) 1999-12-03 2003-05-20 Hid Corporation Interference control method for RFID systems
US6707376B1 (en) 2002-08-09 2004-03-16 Sensormatic Electronics Corporation Pulsed power method for increased read range for a radio frequency identification reader
US7026935B2 (en) 2003-11-10 2006-04-11 Impinj, Inc. Method and apparatus to configure an RFID system to be adaptable to a plurality of environmental conditions
US20060022801A1 (en) 2004-07-30 2006-02-02 Reva Systems Corporation RFID tag data acquisition system
US20060022800A1 (en) 2004-07-30 2006-02-02 Reva Systems Corporation Scheduling in an RFID system having a coordinated RFID tag reader array
US20060022815A1 (en) 2004-07-30 2006-02-02 Fischer Jeffrey H Interference monitoring in an RFID system

Non-Patent Citations (28)

* Cited by examiner, † Cited by third party
Title
Association Francaise de Normalization (AFNOR), "Identification Cards-Contactless Integrated Circuit(s) Cards-Proximity Cards-Part 3: Initalization and Anticollision", ISO/IEC, #ISO/IEC FDIS 1443-3:2000(E), 48 pp. (Jul. 13, 2000).
Association Francaise de Normalization (AFNOR), "Identification Cards-Contactless Integrated Circuit(s) Cards-Proximity Cards-Part 4: Transmission Protocol", ISO/IEC, #ISO/IEC FDIS 14443-4:2000(E), 37 pp. (Jul. 13, 2000).
Association Francaise de Normalization (AFNOR), "Identification Cards-Contactless Integrated Circuit(s) Cards-Vicinity Cards-Part 1: Physical Characteristics", Final Draft, ISO/IEC, #ISO/IEC FDIS 15693-1:2000(E), 8 pp. (Feb. 19, 2000).
Association Francaise de Normalization (AFNOR), "Identification Cards-Contactless Integrated Circuit(s) Cards-Vicinity Cards-Part 2: Air Interface and Initialization", Final Draft, ISO/IEC, #ISO/IEC FDIS 15693-2:2000(E), 23 pp. (Feb. 3, 2000).
Auto-ID Center, Technical Report, "13.56 MHz ISM Band Class 1 Radio Frequency Identification Tag Interface Specification: Recommended Standard", Version 1.0.0, Auto-ID Center, Massachusetts Institute of Technology, 31 pp. (Feb. 1, 2003).
Capetanakis, John I., "Generalized TDMA: The Multi-Accessing Tree Protocol," IEEE Transaction on Communications, vol. Com 27, No. 10, pp. 1476-1484 (Oct. 1979).
Capetanakis, John I., "Tree Algorithms for Packet Broadcast Channels", IEEE Transactions on Information Theory, vol. IT-25, No. 5, pp. 505-515 (Sep. 1979).
ECC Report 1, "Compatability between Inductive LF and HF RFID Transponder and Other Radio Communication Systems in the Frequency Ranges 135-148.5 kHz, 4.78-8.78 MHz and 11.56-15.56 MHz," Electronic Comm. Committee, 14 pp. (Feb. 2002)..
Engels, Daniel, "Technical Report, The Use of the Electronic Product Code", Auto-ID Center, Massachusetts Institute of Technology, 8 pp. (Feb. 1, 2003).
EP serial No. 05016513.3 ; Extended Search Report And Search Opinion; mailed Jan. 22, 2007; 5 pp.
EP serial No. 05016514.1 ; Extended Search Report And Search Opinion; mailed Jan. 26, 2007; 5 pp.
EPC(TM)Radio Frequency identity Protocols Class-1 Generation-2 UHF RFID Protocol for Communications at 860 MHz-960 MHz, EPC Global, Inc. Version 1.0.9, cover sheet and pp. 37-38 (Jan. 2005).
http://216.121.131.129/article/articleview/330/1/1/;"EPC Doesn't Infringe RFID Patents", RFID Journal, 2 pp. (Mar. 4, 2003).
http://money.cnn.com/services/ticketheadlines/prn/citu045.PI.09162003122727.24911.htm, "Manhattan Associates Announces Next-Generation Microsoft-Based RFID Solutions", CNN Money, 3 pp. (Sep. 16, 2003).
http://www.rfid-handbook.com/, "Radio Frequency-Identification; The Authors Homepage of the RFID Handbook", (C) 1998-2006, 2 pp. (reprint Feb. 22, 2007).
http://www.rfidjournal.com/article/articleview/473/1/1/, "Second Source of Class 1 EPC Chips", RFID Journal, 2 pp. (Jun. 26, 2003).
http://www.sal-c.org/, Smart Active Labels (SAL) Consortium), (C) 2007, 1 page (reprinted Apr. 26, 2007).
Humblet, Pierre A., et al., "Efficient Accessing of a Multiaccess Channel", Proc IEEE Conference Decis Control Incl Symp Adapt Processes 1, pp. 624-627 (1980).
International Standard ISO/IEC, "Final Committee Draft, ISO/IEC 14443-1, Identification Cards-Contactless Integrated Circuit(s) Card-Proximity Cards, Part 1: Physical Characteristics", 9 pp. (1997).
ISO, Automatic Identification-Radio Frequency Identification for Item Management-Communications and Interfaces-Part 3, Physical Layer, Anti collision System and Protocol Values at 13.56 MHz MODE 4, #ISO/WD 18000-3-v40-4, 24 pp. (Mar. 1, 2001).
ISO/IEC, "Automatic Identification-Radio Frequency Identification for Item Management-Communications and Interfaces-Part 3: Physical Layer, Anti-Collision System and Protocol Values at 13.56 MHz-MODE 1", ISO/IEC, #ISO/WD 18000-3-v40-1, 105 pp. (Mar. 1, 2001).
ISO/IEC, "Final Committee Draft, ISO/IEC 14443-2, Identification Cards-Contactless Integrated Circuit(s) cards-Proximity Cards-Part 2: Radio Frequency Power and Signal Interface", Editor D. Baddeley, #ISO/IEC JTC/SC17/WG8, 16 pp. (Mar. 26, 1999).
ISO/IEC, "Identification Cards-Contactless Integrated Circuit(s) Cards-Vicinity Cards-Part 3: Anticollision and Transmission Protocol", ISO/IEC, #ISO/IEC CD 15693-3:1999(e), 48 pp. (Nov. 17, 1999).
ISO/IEC, "ISO/IEC 18000, p. 3, Information Technology AIDC Techniques-RFID for Item Management-Air Interface, Part 3, Parameters for Air Interface Communications at 13.56 MHz", #ISO IEC SC31 WG4 FCD18000-3, 176 pp. May 27, 2002).
U.S. Appl. No. 11/607,263 filed Dec. 2006, Tuttle,
Whitepaper, "Understanding Gen 2: What It Is, How You Will Benefit and Criteria for Vendor Assessment", Symbol Technologies, Inc., 8 pp. (Jan. 2006).
Wolf, Jack Keil, "Principles of Group Testing and an Application to the Design and Analysis of Multi-Access Protocols," NATO ASI Series E, Applied Sciences, N. 91, pp. 237-257 (1985).
Wright, Jim, "Trends and Innovations in RF Identification", SUN Microsystems, Inc., (presentation); 30 pp. (Mar. 2005).

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