A system and method for identifying a specific RFID tag includes RFID reader circuitry, such as within an RFID reader, configured for sending and receiving RF signals to detect RFID tags and for obtaining signal parameter information associated with the RFID tags. Processing circuitry is configured for using the signal parameter information for one or more tags of the RFID tags and calculating a tag score for the one or more RFID tags. The processing circuitry is further configured for determining a specific RFID tag using the tag scores for the one or more RFID tags.

A radio frequency identification method and a reader, the reader comprises a camera, a display screen, a distance sensor, an antenna unit and a processor, the camera is configured to collect an image of a target electronic tag, and the display screen is configured to display an image of the target electronic tag, the distance sensor is configured to measure the distance d between the target electronic tag and the reader, and the antenna unit is configured to receive a radio frequency signal emitted by the target electronic tag. When the antenna unit only receives a radio frequency signal transmitted by one electronic tag, the reader reads the electronic tag; when the antenna unit receives radio frequency signals transmitted by a plurality of electronic tags, the processor filters out the target electronic tag according to the matching degree between the distance and a phase value of the radio frequency signal.

A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGO RFID backscatter transponders, SEGO RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.

A system, exhibiting a communication station for communicating with a number of radio tags in a time slot communication process, in which a number of time slots per time slot cycle in a repeating sequence are available for communication, and each time slot is characterized by a distinct time slot symbol, wherein the communication station is designed to send out a synchronization data signal exhibiting the time slot symbol for the currently present time slot, and wherein a radio tag is designed for changing from a sleep state into an active state at a wakeup instant, and for receiving the synchronization data signal in the active state and, if the received time slot symbol indicates a time slot intended for it, for defining a new wakeup instant corresponding to the next appearance of the time slot intended for it in a time slot cycle that follows the currently present time slot cycle.

A method of addressing one or more RFID devices within a group of RFID devices includes transmitting a command to respond to the group at a first modulation depth. The method further includes receiving a response from a first sub-group of RFID devices in the group that have a minimum modulation depth less than or equal to the first modulation depth. The method further includes transmitting the command to respond to the group at a second modulation depth higher than the first modulation depth. The method further includes receiving a response from a second sub-group of RFID devices within the group that have a minimum modulation depth less than or equal to the second modulation depth. The method is also directed to authenticating RFIDs by comparing a measured minimum modulation depth to a known minimum modulation depth.

A system, exhibiting a communication station for communicating with a number of radio tags in a time slot communication process, in which a number of time slots per time slot cycle in a repeating sequence are available for communication, and each time slot is characterized by a distinct time slot symbol, wherein the communication station is designed to send out a synchronization data signal exhibiting the time slot symbol for the currently present time slot, and wherein a radio tag is designed for changing from a sleep state into an active state at a wakeup instant, and for receiving the synchronization data signal in the active state and, if the received time slot symbol indicates a time slot intended for it, for defining a new wakeup instant corresponding to the next appearance of the time slot intended for it in a time slot cycle that follows the currently present time slot cycle.

Methods, systems, apparatus, and articles of manufacture are disclosed to improve radio frequency identification (RFID) tag communication. An example disclosed apparatus includes an RFID reader monitor to activate a first RFID reader and deactivate a second RFID reader during a first tag data acquisition at a first time, and deactivate the first RFID reader and activate the second RFID reader during a second tag data acquisition at a second time, a tag logger to identify a first set of RFID tags detected by the first RFID reader at the first time, and identify a second set of RFID tags detected by the second RFID reader at the second time, and a group generator to improve RFID tag communication by identifying which one of the first RFID reader and the second RFID reader communicates with a common RFID tag.

A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGOTM RFID backscatter transponders, SEGOTM RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.

RFID tags are used for many purpose including tracking. RFID interrogators are used to retrieve information from tags. In many applications, a plurality of RFID interrogators are required. Synchronization between interrogators in the same theatre of operation is critical to ensure that their broadcasts do not interfere with each other. In fixed RFID interrogator applications, RFID interrogators can be wired together allowing a channel to synchronize the transmissions of the RFID interrogators. Methods described herein can ensure that synchronization is maintained in the event of the failure of a synchronizing master. Furthermore, additional methods for synchronizing RFID interrogators in wireless applications are described allowing synchronization in the absence of wired connections between interrogators.

Embodiments provide an RFID reader. The RFID reader includes a collision detector, a decoder and a frame length adjuster. The collision detector is configured to detect for each slot of a plurality of slots of a current frame, in which a collision of signals transmitted by at least two RFID tags occurred, a signal property of a signal of the signals transmitted by at least two RFID tags. The decoder is configured to decode for the slot in which the collision is detected the signal of the signals transmitted by the at least two RFID tags using the detected signal property, wherein a collision recover probability describing a probability that the decoder can accurately decode the one signal depends on a signal-to-noise ratio (SNR) of the current frame. The frame length adjuster is configured to adjust a frame length of a subsequent frame in dependence on the collision recover probability.