Systems and methods for self-checkout using an RFID tag. The methods comprise: detecting motion of the RFID tag using a motion sensor local to the RFID tag; enabling at least one communication operation of the RFID tag in response to the detection of the RFID tag's motion; performing operations by the RFID tag to communicate first information to an enterprise system; using the first information by the enterprise system to associate the RFID tag with an individual of a plurality of individuals present in a given facility; and dynamically changing displayed content of a display device to include information about an object to which the RFID tag is coupled, the display device being in proximity to the individual, in the possession of the individual or being worn by the individual.

A method for interleaving time slots in a multi-antenna system for communication with RFID tags is described. An exemplary system has a first RFID interrogator and first and second antennas. The first and second antennas direct signals to and receive signals from respective first and second interrogation zones. A first interrogation signal is transmitted to the first antenna. A first acquire window for receiving a signal from a first RFID transponder is opened after the first interrogation signal. A second interrogation signal is transmitted to the second antenna after the first interrogation signal, and a second acquire window for receiving a signal from a second RFID transponder is opened after the second interrogation signal.

An interrogator receives a response from a responder that has detected a predetermined state with priority among responses from a plurality of responders. A tag determines a time slot selected in a case in which a sensor has detected a predetermined state to be a time slot earlier than a time slot selected in a case in which the sensor has not detected the predetermined state.

Methods and apparatus are provided for handling the response sequence with geometric elimination of a plurality of keyless fobs. The remote fobs are interrogated with a body control module. A first signal is issued from a first set of remote fobs in a first time slot in response to the interrogation signal from the body control module. A second signal is issued from a second set of remote fobs in a second time slot in response to the interrogation signal from the body control module. The second time slot differs from the first time slot. A first remote fob is authenticated when the first signal is received by the body control module in a free and clear state. The second remote fob is authenticated when the second signal is received by the body control module in the free and clear state. If neither the first nor second signals are received in the free and clear state, the remote fobs are re-interrogated by the body control module.

Systems and methods for operating a Radio Frequency Identification (RFID) tag. The methods comprise: monitoring a level of Radio Frequency (RF) energy being received by the RFID tag; performing operations by a circuit of the RFID tag to compare the level of RF energy in a given frequency band to a first threshold value; and transitioning an operational mode of the RFID tag from a first operational mode in which a receiver is disabled to a second operational mode in which the receiver is enabled, when the level of RF energy exceeds the first threshold value. The RFID tag is able to communicate with a remote tag reader when the RFID tag is in the second operational mode and not when the RFID tag is in the first operational mode.

Various embodiments relate to a method for classifying received radio frequency signals, including: receiving an input signal; matched filtering the input signal to produce a correlation result signal; sampling the correlation result signal at a plurality of half-bit-grids and a plurality of bit-grids to produce a set of modulated phase correlation result samples and a set of non-modulated phase correlation result samples; calculating a minimum of the set of modulated phase correlation result samples; calculating a maximum of the set of non-modulated phase correlation result samples; and classifying the input signal as valid data or collision data based on the minimum and the maximum.

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 theater 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.

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 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.

According to one embodiment, a wireless tag communication apparatus includes a plurality of communication units configured to communicate with a wireless tag. The communication units are disposed such that communicable ranges of the communication units overlap each other. A control unit controls each of the plurality of communication units to alternate between a communication state and a pause state. When the wireless tag is positioned within communication ranges of both first and second communication units of the plurality of communication units, the control unit controls the first communication unit to be in the communication state and the second communication unit to be in the pause state.