Methods and an apparatus for implementing a read cycle for identifying RFID tags among a plurality of RFID tags is disclosed. The read cycle comprises of selecting a group of items for reading and receiving identifiers from one or more items of the group, determining an aggregate data of the received identifiers, and comparing the aggregate data of the received identifiers with the aggregate data for the group from a previous read cycle. Further, where the aggregate data compared is equal, the read cycle is terminated, or where the aggregate data compared is not equal, the read cycle is repeated by forming at least one new group or by dividing the group into at least two subgroups and running the read cycle for each subgroup. The read cycle is performed in a time proportional to the number of tags that have changed and logarithmic in the total number of tags.

When multiple readers for RF transponders have to be placed in close proximity, such as in adjacent lanes of a highway toll barrier, they can be set to operate at different frequencies. When signals from two adjacent ones of the readers interfere, the resulting signal includes interference terms whose frequencies equal the sum of the reader frequencies and the difference between the reader frequencies. To remove such interference terms while passing the desired terms, a tag includes a low-pass or other frequency-selective filter.

An RFID reading device according to the present invention includes: response requesting unit (20) configured to output a response request signal to a wireless tag; response reception unit (24) configured to extract an ID of the wireless tag and detecting a signal collision of a response from the wireless tag, based on a response signal output from the wireless tag in response to the response request signal; reading result acquisition unit (25) configured to acquire a read tag number indicating the number of wireless tags from which the corresponding ID has been successfully read; collision occurrence status acquisition unit (26) configured to count the number of time slots in which the signal collision has occurred and calculating the number of collisions; and reading result complementing unit (27) configured to estimate the number of readable wireless tags based on the read tag number and the number of collisions.

An apparatus, system, and method for wireless communication with remote devices that reduce or eliminate interference from zero-mean noise and deterministic signals within the operating system frequency band are provided. An interrogator uses dithering of the initiation time of sequential transmitted signals or sets of transmitted signals with synchronous accumulation of the resulting received signals to reduce the relative strength of interfering signals while increasing the relative strength of the desired signal. The apparatus, system, and method are particularly advantageous when used to extract identification and/or sensor data from passive wireless sensors and tags.

Methods and an apparatus for implementing a read cycle for identifying RFID tags among a plurality of RFID tags is disclosed. The read cycle comprises of selecting a group of items for reading and receiving identifiers from one or more items of the group, determining an aggregate data of the received identifiers, and comparing the aggregate data of the received identifiers with the aggregate data for the group from a previous read cycle. Further, where the aggregate data compared is equal, the read cycle is terminated, or where the aggregate data compared is not equal, the read cycle is repeated by forming at least one new group or by dividing the group into at least two subgroups and running the read cycle for each subgroup. The read cycle is performed in a time proportional to the number of tags that have changed and logarithmic in the total number of tags.

This application discloses a method and apparatus for backscatter signal transmission, a communication device, and a readable storage medium. The method includes: determining, by a tag based on first information, a parameter related to transmission of a backscatter signal; where the first information includes at least one of the following: a first identifier, where the first identifier includes an identifier of the tag or a temporary identifier of the tag; a first value, where the first value is used to indicate a random number generated by the tag; a second value, where the second value is used to indicate a counter value of the tag; a third value, where the third value is used to indicate a counter step of the tag; a group identifier or intra-group identifier of the tag; a session number or a process number; or information received from a reader/writer.

When multiple readers for RF transponders have to be placed in close proximity, such as in adjacent lanes of a highway toll barrier, they can be set to operate at different frequencies. When signals from two adjacent ones of the readers interfere, the resulting signal includes interference terms whose frequencies equal the sum of the reader frequencies and the difference between the reader frequencies. To remove such interference terms while passing the desired terms, a tag includes a low-pass or other frequency-selective filter.

A method for recognizing a tag in an environment where the same frequency band is in use and an NFC device for the same are provided. Depending on whether a radio channel is in use, the NFC device changes a first operation mode to a second operation mode, requests slot assignment for tag recognition at the second operation mode, and changes the second operation mode back to the first operation mode to perform a tag recognition process at an assigned slot.

Enhanced surface acoustic wave (SAW) sensors and SAW sensor-tag wireless interface devices, including low loss devices, devices that enable enhanced use of time diversity for device identification, and devices suitable for use in band-limited environments (such as ISM band) and for use in ultra-wideband applications are disclosed. Antennas for use with both SAW sensors and/or tags, and wireless transceiver systems also are disclosed, including antennas suitable for operation in conductive media and in highly metallic environments, said antennas being used to activate and read said SAW sensors and/or tags. SAW sensors and sensor-tags and related methods for measuring scaled voltage and current in electrical conductors via measurements of the electric and magnetic fields thereof are disclosed.

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.