Abstract: Systems and methods for generating sensor tag locations expressed in a three-dimension global coordinate system from sensor tag locations expressed in three-dimensional local coordinate systems of mobile readers that read each tag and for updating the paths of each mobile reader are disclosed. In one embodiment, a method includes receiving sensor data from one or more mobile reader agents, receiving tag location data that describes the location of one or more sensor tags expressed in local coordinates of the subspace of the mobile reader agent that read the sensor tag, converting the tag location data into a global coordinate system that is common to all mobile reader agents, and updating one or more paths of one or more mobile reader agents to increase the coverage of reading tags in the subspace of the mobile reader agent.

Abstract: Systems and methods for providing an estimate of a population of passive Radio Frequency Identification (RFID) sensors in a coverage area of an RFID reader system are disclosed. In accordance with embodiments of this invention, the contention resolutions or results of each slot in an interrogation receive frame are determined. The contention resolutions are then used to determine the probabilities of different population estimates. A population estimate is then selected as the population based on the probability of the estimate meeting predetermined criteria.

Abstract: Systems and methods for detecting collisions in radio frequency tags in accordance with embodiments of the invention are disclosed. In one embodiment, a receiver system includes a receiver configured to receive and sample a phase modulated input signal, and a multiple symbol noncoherent soft output detector configured to receive the sampled input signal and to generate a soft metric indicative of the reliability of a detected symbol based upon observations over multiple symbols, a collision detector configured to calculate a decision metric from a set of soft metrics generated by the multiple symbol noncoherent soft output detector and detect a collision when the decision metric satisfies a predetermined criterion.

Abstract: Systems and methods for locating one or more radio frequency identification (RFID) tags are provided. A phase difference of received information signals of illuminated RFID tags is utilized to locate the RFID tags. One or more exciters transmit interrogation signals to illuminate the RFID tags in which the exciters may have a plurality of antenna selectively configured to transmit through two or more antennas and to receive on one antenna. Multiple reads of the same RFID tag can also be performed to generate a probability model of the location of the RFID tag. An enhanced particle filter is applied to probability model to determine the exact location of the RFID.

Abstract: Systems and methods for detecting collisions in radio frequency tags in accordance with embodiments of the invention are disclosed. In one embodiment, a receiver system includes a receiver configured to receive and sample a phase modulated input signal, and a multiple symbol noncoherent soft output detector configured to receive the sampled input signal and to generate a soft metric indicative of the reliability of a detected symbol based upon observations over multiple symbols, a collision detector configured to calculate a decision metric from a set of soft metrics generated by the multiple symbol noncoherent soft output detector and detect a collision when the decision metric satisfies a predetermined criterion.

Abstract: Systems and methods for locating one or more radio frequency identification (RFID) tags are provided. A phase difference of received information signals of illuminated RFID tags is utilized to locate the RFID tags. One or more exciters transmit interrogation signals to illuminate the RFID tags in which the exciters may have a plurality of antenna selectively configured to transmit through two or more antennas and to receive on one antenna. Multiple reads of the same RFID tag can also be performed to generate a probability model of the location of the RFID tag. An enhanced particle filter is applied to probability model to determine the exact location of the RFID.

Abstract: Systems and methods for providing an estimate of a population of passive Radio Frequency Identification (RFID) sensors in a coverage area of an RFID reader system are disclosed. In accordance with embodiments of this invention, the contention resolutions or results of each slot in an interrogation receive frame are determined. The contention resolutions are then used to determine the probabilities of different population estimates. A population estimate is then selected as the population based on the probability of the estimate meeting predetermined criteria.

Abstract: Systems and methods for reading RFID tags using joint beamforming and preamble detection in accordance with embodiments of the invention are disclosed. One embodiment includes an antenna array comprising a plurality of antenna elements, a joint beamformer and preamble detector configured to receive inputs from each of the antenna elements, and a decoder configured to receive a resampled signal from the joint beamformer and preamble detector and to decode data using the resampled signal. In addition, the joint beamformer and preamble detector is configured to correlate the inputs from the antenna elements against a correlation sequence at a plurality of starting sample positions and predetermined rates, use the correlations to select a starting sample position and rate for decoding the received signal, use the correlations to determine beamforming coefficients for combining the inputs, and resample the combined inputs based upon the selected starting sample position and rate.

Abstract: RFID systems for locating RFID tags utilizing phased array antennas and compressed sensing processing techniques in accordance with embodiments of the invention are disclosed. In one embodiment of the invention, an RFID system includes at least one exciter that includes at least one transmit antenna, a phased antenna array that includes a plurality of receive antennas, and an RFID receiver system configured to communicate with the at least one exciter and connected to the phased antenna array, where the RFID receiver system is configured to locate an RFID tag by performing reads of the RFD tag at multiple frequencies, generating a measurement matrix, and determining a line of sight (LOS) distance between the activated RFID tag and each of the plurality of receive antennas by eliminating bases from the measurement matrix.

Abstract: A multi-protocol, multi-band array antenna system may be used in Radio Frequency Identification (RFID) system reader and sensory networks. The antenna array may include array elements with an integrated low noise amplifier. The system may employ digital beam forming techniques for transmission and steering of a beam to a specific sensor tag or group of tags in a cell. The receive beam forming network is optimized for detecting signals from each sensor tag. Narrow and wideband interferences may be excised by an interference nulling algorithm. Space division multiplexing may be used by the antenna system to enhance system processing capacity.

Abstract: Systems and methods for detecting collisions in radio frequency tags in accordance with embodiments of the invention are disclosed. In one embodiment, a receiver system includes a receiver configured to receive and sample a phase modulated input signal, and a multiple symbol noncoherent soft output detector configured to receive the sampled input signal and to generate a soft metric indicative of the reliability of a detected symbol based upon observations over multiple symbols, a collision detector configured to calculate a decision metric from a set of soft metrics generated by the multiple symbol noncoherent soft output detector and detect a collision when the decision metric satisfies a predetermined criterion.

Abstract: Systems and methods for decoding data transmitted by RFID tags are disclosed. One embodiment of the invention includes an analyzer and equalizer configured to filter an input signal, an estimation block configured to obtain a baseband representation of the modulated data signal by mixing the filtered input signal with the carrier wave, and a coherent detector configured to perform phase and timing recovery on the modulated data signal in the presence of noise and to determine a sequence of data symbols.

Abstract: RFID data signals from RFID tags may be recovered by determining the probabilities of transitions between data states between a series of a pairs of signal samples using a set of predetermined probabilities related to data, timing, baud rate and/or phase variables affecting the received signal and processing those determined probabilities to determine the sequence of such transitions that has the highest probability of occurrence. A second set of predetermined probabilities related to transitions in the opposite direction may be used to sequence in a reverse direction. The determination of the sequence representing the RFID tag data may be iterated in both directions until further iterations do not change the determined probabilities.

Abstract: Systems and methods for reading RFID tags using joint beamforming and preamble detection in accordance with embodiments of the invention are disclosed. One embodiment includes an antenna array comprising a plurality of antenna elements, a joint beamformer and preamble detector configured to receive inputs from each of the antenna elements, and a decoder configured to receive a resampled signal from the joint beamformer and preamble detector and to decode data using the resampled signal. In addition, the joint beamformer and preamble detector is configured to correlate the inputs from the antenna elements against a correlation sequence at a plurality of starting sample positions and predetermined rates, use the correlations to select a starting sample position and rate for decoding the received signal, use the correlations to determine beamforming coefficients for combining the inputs, and resample the combined inputs based upon the selected starting sample position and rate.

Abstract: RFID systems are disclosed that include at least one RFID receiver system and a distributed exciter architecture. Exciters can be connected via wired and/or wireless connections to the RFID receiver system, which can control activation of the exciters to detect the presence of RFID tags within interrogation spaces defined by the exciter topology. One embodiment includes an RFID receiver system configured to detect information from RFID tags within a receive coverage area, and a plurality of exciters defining a plurality of interrogation spaces within the receive coverage area of the receiver system. The receiver system is configured to transmit a control signal that identifies one of the exciters and includes information indicative of an RFID tag interrogation signal, the exciters are configured to receive the control signal, and the exciter identified in the control signal is configured to illuminate an interrogation space with the RFID tag interrogation signal.

Abstract: RFID systems for locating RFID tags utilizing phased array antennas and compressed sensing processing techniques in accordance with embodiments of the invention are disclosed. In one embodiment of the invention, an RFID system includes at least one exciter that includes at least one transmit antenna, a phased antenna array that includes a plurality of receive antennas, and an RFID receiver system configured to communicate with the at least one exciter and connected to the phased antenna array, where the RFID receiver system is configured to locate an RFID tag by performing reads of the RFD tag at multiple frequencies, generating a measurement matrix, and determining a line of sight (LOS) distance between the activated RFID tag and each of the plurality of receive antennas by eliminating bases from the measurement matrix.

Abstract: Systems and methods for providing an estimate of a population of passive Radio Frequency Identification (RFID) sensors in a coverage area of an RFID reader system are disclosed. In accordance with embodiments of this invention, the contention resolutions or results of each slot in an interrogation receive frame are determined. The contention resolutions are then used to determine the probabilities of different population estimates. A population estimate is then selected as the population based on the probability of the estimate meeting predetermined criteria.

Abstract: Systems and methods for decoding data transmitted by RFID tags are disclosed. One embodiment of the invention includes an analyzer and equalizer configured to filter an input signal, an estimation block configured to obtain a baseband representation of the modulated data signal by mixing the filtered input signal with the carrier wave, and a coherent detector configured to perform phase and timing recovery on the modulated data signal in the presence of noise and to determine a sequence of data symbols.

Abstract: Systems and methods for locating one or more radio frequency identification (RFID) tags are provided. A phase difference of received information signals of illuminated RFID tags is utilized to locate the RFID tags. One or more exciters transmit interrogation signals to illuminate the RFID tags in which the exciters may have a plurality of antenna selectively configured to transmit through two or more antennas and to receive on one antenna. Multiple reads of the same RFID tag can also be performed to generate a probability model of the location of the RFID tag. An enhanced particle filter is applied to probability model to determine the exact location of the RFID.

Abstract: A multi-protocol, multi-band array antenna system may be used in Radio Frequency Identification (RFID) system reader and sensory networks. The antenna array may include array elements with an integrated low noise amplifier. The system may employ digital beam forming techniques for transmission and steering of a beam to a specific sensor tag or group of tags in a cell. The receive beam forming network is optimized for detecting signals from each sensor tag. Narrow and wideband interferences may be excised by an interference nulling algorithm. Space division multiplexing may be used by the antenna system to enhance system processing capacity.