Abstract: In one among many embodiments, the invention provides a system including an interrogator communicating to a selected one or more of a number of communications devices. A plurality of communications devices select random values independently of random values selected by other devices. The interrogator transmits a first signal requesting devices within a specified group of devices to respond, the specified group being less than or equal to all of the devices within a field of the interrogator. Devices receiving the first signal respectively determine if the respective device falls within the specified group and, if so, send a reply including a respective random value to the interrogator within a randomly selected time slot of a number of slots; and, if not, do not send a reply. The interrogator determines if a collision occurred between devices that sent a reply. The interrogator also creates a new, different specified group.

Abstract: A target radio frequency identification (RFID) device may include a receiver to receive valid bits common to a first set of random numbers and to receive a signal indicating a change in a number of time slots from a first number of a plurality of time slots to a second number of a plurality of time slots in which the target device may respond. The target device may include processing circuitry to generate a random number, to determine if the random number is in the first set, to generate a random value, and to randomly select a time slot. The target device may further include a transmitter to communicate a response if the random number is determined to be in the first set, and to communicate the random value during the randomly selected time slot.

Abstract: A method of establishing wireless communications between an interrogator and individual ones of multiple wireless identification devices, the method comprising combining tree search and Aloha methods to establish communications between the interrogator and individual ones of the multiple wireless identification devices without collision. A system comprising an interrogator, and a plurality of wireless identification devices configured to communicate with the interrogator in a wireless fashion, the respective wireless identification devices having a unique identification number, the interrogator being configured to employ tree search and Aloha techniques to determine the unique identification numbers of the different wireless identification devices so as to be able to establish communications between the interrogator and individual ones of the multiple wireless identification devices without collision by multiple wireless identification devices attempting to respond to the interrogator at the same time.

Abstract: RFID tags are identified. In one embodiment, RFID tags may be chosen to respond to an interrogator in accordance with an arbitration scheme. According to one arbitration scheme, each chosen tag may randomly pick a slot value. The interrogator may indicate that the number of slot values is to be adjusted. Each chosen tag may respond to the interrogator with a random number.

Abstract: An RFID tag population is selected by an interrogator. Each tag of the selected tag population then responds to the interrogator in accordance with a slotted arbitration scheme. According to the slotted arbitration scheme, each tag of the selected tag population picks its own random value from a range of integers indicated by the interrogator. The random value corresponds to a slot. The interrogator may indicate that the range of integers is to be adjusted. Each tag of the selected tag population responds to the interrogator with a random number.

Abstract: A wireless communications system comprising a first transponder adapted to be coupled to one of a plurality of selectable antennas, having a look-up table including locations holding data representing antennas, and having pointers pointing to selected ones of the locations, the pointers defining an order in which antennas will be used to attempt communication; and a second transponder configured to communicate with the first transponder, wherein the first transponder uses an antenna defined by data in one location of the table for communication with the second transponder, and, if successful communication with the second transponder is not established, the first transponder uses an antenna defined by data in another location of the table selected in accordance with the order defined by the pointers.

Abstract: A wireless communications system comprising a first transponder adapted to be coupled to one of a plurality of selectable antennas, having a look-up table including locations holding data representing antennas, and having pointers pointing to selected ones of the locations, the pointers defining an order in which antennas will be used to attempt communication; and a second transponder configured to communicate with the first transponder, wherein the first transponder uses an antenna defined by data in one location of the table for communication with the second transponder, and, if successful communication with the second transponder is not established, the first transponder uses an antenna defined by data in another location of the table selected in accordance with the order defined by the pointers.

Abstract: A wireless communications system comprising a first transponder adapted to be coupled to one of a plurality of selectable antennas, having a look-up table including locations holding data representing antennas, and having pointers pointing to selected ones of the locations, the pointers defining an order in which antennas will be used to attempt communication; and a second transponder configured to communicate with the first transponder, wherein the first transponder uses an antenna defined by data in one location of the table for communication with the second transponder, and, if successful communication with the second transponder is not established, the first transponder uses an antenna defined by data in another location of the table selected in accordance with the order defined by the pointers.

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 establish communications without collision between the interrogator and individual ones of the multiple wireless identification devices, a search tree being defined for the tree search method, the tree having multiple levels representing subgroups of the multiple wireless identification devices, the number of devices in a subgroup in one level being half of the number of devices in the next higher level, the tree search method employing level skipping wherein at least one level of the tree is skipped.

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 establish communications without collision between the interrogator and individual ones of the multiple wireless identification devices, a search tree being defined for the tree search method, the tree having multiple levels respectively representing subgroups of the multiple wireless identification devices, the method further comprising starting the tree search at a selectable level of the search tree.

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 establish communications without collision between the interrogator and individual ones of the multiple wireless identification devices, a search tree being defined for the tree search method, the tree having multiple levels representing subgroups of the multiple wireless identification devices, the number of devices in a subgroup in one level being half of the number of devices in the next higher level, the tree search method employing level skipping wherein at least one level of the tree is skipped.

Abstract: A wireless communications system comprising a first transponder adapted to be coupled to one of a plurality of selectable antennas, having a look-up table including locations holding data representing antennas, and having pointers pointing to selected ones of the locations, the pointers defining an order in which antennas will be used to attempt communication; and a second transponder configured to communicate with the first transponder, wherein the first transponder uses an antenna defined by data in one location of the table for communication with the second transponder, and, if successful communication with the second transponder is not established, the first transponder uses an antenna defined by data in another location of the table selected in accordance with the order defamed by the pointers.

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.

Abstract: A wireless communications system comprising a first transponder adapted to be coupled to one of a plurality of selectable antennas, having a look-up table including locations holding data representing antennas, and having pointers pointing to selected ones of the locations, the pointers defining an order in which antennas will be used to attempt communication; and a second transponder configured to communicate with the first transponder, wherein the first transponder uses an antenna defined by data in one location of the table for communication with the second transponder, and, if successful communication with the second transponder is not established, the first transponder uses an antenna defined by data in another location of the table selected in accordance with the order defined by the pointers.

Abstract: A method of establishing wireless communications between an interrogator and individual ones of multiple wireless identification devices, the method comprising combining tree search and Aloha methods to establish communications between the interrogator and individual ones of the multiple wireless identification devices without collision. A system comprising an interrogator, and a plurality of wireless identification devices configured to communicate with the interrogator in a wireless fashion, the respective wireless identification devices having a unique identification number, the interrogator being configured to employ tree search and Aloha techniques to determine the unique identification numbers of the different wireless identification devices so as to be able to establish communications between the interrogator and individual ones of the multiple wireless identification devices without collision by multiple wireless identification devices attempting to respond to the interrogator at the same time.

Abstract: A method of protecting data in a smart card from unauthorized access, the method comprising providing a housing defined by first and second housing portions; employing a volatile memory in the smart card for storing the data, and supporting the volatile memory from the first housing portion; providing a power supply in the housing, the power supply maintaining the data in the volatile memory while the power supply is connected to the volatile memory; and connecting the power supply to the volatile memory using a conductor supported by and movable with the second housing portion.

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.

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.

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.

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 establish communications without collision between the interrogator and individual ones of the multiple wireless identification devices, a search tree being defined for the tree search method, the tree having multiple levels respectively representing subgroups of the multiple wireless identification devices, the method further comprising starting the tree search at a selectable level of the search tree.