Abstract: Methods and apparatuses for secure communications of confidential information are provided. In an embodiment, a method of communicating with a population of radio frequency identification tags includes transmitting a first interrogation signal, receiving a response to the first interrogation signal from at least one RFID tag at a first received signal strength including at least a portion of a first identification code, and transmitting a second interrogation signal that includes a request for confidential information, a command to transmit a response to the second interrogation signal at a secure power level, and the first identification code. In another embodiment, a method for communicating with an RFID tag includes receiving an interrogation signal that includes a request for confidential information and transmitting a response to the interrogation signal at a secure power level. The response includes the confidential information.

Abstract: Methods and apparatuses are described for reducing interference amongst frequency identification (RFID) readers operating within an interference range. Groups of frequencies from a range of frequencies are determined such that RFID readers transmitting on adjacent frequencies in a particular group of frequencies experience substantially negligible interference. A first group of frequencies is selected for a first time period of operation. RFID readers are each assigned a unique frequency from the first group of frequencies. At the end of the first time period, a second group of frequencies is selected and RFID readers are each assigned unique frequencies from the second group of frequencies. Substantially all frequencies of the groups of frequencies are assigned during a predetermined time duration.

Abstract: A system comprising a transmitter element creating an interrogation signal and transmitting the interrogation signal and a receiver element receiving a reflection signal of the interrogation signal and combining the reflection signal and a feedback signal to cancel at least a portion of radio frequency echo signals in the reflection signal.

Abstract: The present invention provides methods and apparatuses for demodulation and decoding of backscattered 16-QAM RFID tag signals, represented by their in-phase and quadrature components at the output of the demodulator in the receiver portion of a reader interrogator. In a communication channel with fast changing parameters, a reader receiver adaptively and coherently corrects the in-phase and quadrature-phase components of a signal received from a tag by tracking the phase and amplitude of the signal based on a decision-feedback. A reference signal is used to correct the signal components, where the coordinates of the reference signal is updated by a tracking and an averaging algorithm. A simple implementation of the receiver in a digital signal processing environment is enabled.

Abstract: A method for pipelined processing of access commands to a population of radio frequency identification (RFID) tags is provided. The method includes transmitting a first queued access command to a first tag in the population of RFID tags, transmitting a second queued access command to a second tag in the population of RFID tags, and transmitting a status request command to the first tag. The queued access command causes the first tag to perform an operation and upon completion of the operation, to suspend transaction processing. The second queued access command is transmitted while the first tag is performing the command operation. The status request command causes the first tag to resume normal processing.

Abstract: The present invention is directed to systems that use frequency selective surfaces (FSS) to aid in the operation of radio frequency identification (RFID) devices and products. In one embodiment, a system for interrogating radio frequency identification (RFID) tags includes a conveyor belt and an RFID reader. The conveyor belt has a first surface and a second surface. The first surface is configured to receive an item to which an RFID tag is affixed and the second surface is configured to slide on a metal slide plate. The RFID reader is configured to transmit instructions embodied in a radio frequency (RF) signal to the RFID tag, wherein the metal slide plate is positioned between the RFID reader and the RFID tag and comprises a frequency selective surface that is substantially transparent to the RF signal.

Abstract: Methods, systems, and apparatuses for quadrature amplitude modulation (QAM) based radio frequency identification (RFID) systems are described. In an aspect, a tag transmitter performs QAM signal mapping and quadrature modulation of a carrier wave (CW), to transmit a QAM response signal. In another aspect, a QAM-enabled reader receiver receives the QAM tag response signal, and performs quasi-coherent signal processing, based on tracking of QAM signal parameters in a decision feedback loop.

Abstract: A thermal management system and method to control temperature in an RFID reader is described herein. In particular, by inserting variable periods of inactivity (or latency) at the beginning or at the end of each read cycle, proportional to an instantaneous temperature value of the RFID reader, over-heating and damage of RFID reader electronics is prevented. The RFID reader includes a thermal sensor and determines when the high power RF electronics is enabled. If the RFID reader is in an over-heated condition, it can be turned OFF and during this period any requests received on an interface to the RFID reader to perform a read of tag(s) are not processed.

Abstract: Methods and apparatuses for tracking an item having an associated radio frequency identification (RFID) tag are described. A change in a physical attribute of the item is detected. Information stored in the tag is updated based on the detected change. Information stored in a database may also be updated based on the detected change. In another aspect, a second tag associated with a person is determined to be located within a predetermined range of a first tag associated with an item. As a result, information is stored in the first tag regarding the person.

Abstract: Methods and systems are provided for improved protection of radio frequency identification tag memory by using two or more “brownout-safe” pointer registers (instead of a single pointer register) that are logically concatenated to form a complete address for the boundary between a locked portion and an unlocked portion of the tag memory. A first pointer is a coarse pointer identifying a block of memory containing the boundary. A second pointer is a fine pointer identifying a specific location within the identified coarse block of memory. The coarse pointer may be a gray-coded or linear pointer. Similarly, the fine pointer may be a gray-coded or linear pointer.

Abstract: Methods, systems, and apparatuses for detecting a reader signal strength in a radio frequency identification (RFID) tag is described. A tag is configured to monitor an attribute of a reader transmitted signal, such as the signal strength. The tag generates an indication of the signal attribute, and transmits the indication of the signal attribute to the reader.

Abstract: Methods, systems and apparatuses for RFID readers forming a reader network are described. In an aspect of the present invention, a plurality of RFID readers are configured to interrogate tags. Furthermore, the readers are configured to communicate with one another by transferring a token, represented by a signal. Possession of the token enables the reader to access a RF communications medium. Readers can be arranged in a ring configuration, and interconnected via wired links. A secondary token may circulate in the ring in addition to the primary token, to ensure redundancy in the system. A reader waits for a predetermined time interval before accessing the RF communications medium.

Abstract: Methods and apparatuses for assembling and implementing tamper indicating RFID devices are presented. An RFID device includes a substrate, an electrically conductive pattern formed on the substrate configured to operate as an antenna by separating a portion of a first device section from a second device section, and an electrical circuit mounted on the substrate that is electrically coupled to the antenna. The electrical circuit stores an identification code.

Abstract: Described is an RFID tracking system, an RFID tag and method, The tag includes a memory storing identification data and a radio frequency transceiver receiving a signal from a first wireless transceiver. The first wireless transceiver is part of a wireless wide area network (WWAN). The radio frequency transceiver transmits a response signal including the identification data to at least one second wireless transceiver. The at least one second wireless transceiver being part of a wireless local area network (WLAN). A location of the RFID tag is determined as a function of the response signal.