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US 10,095,892 B2Granted
RFID reader and method for recognizing RFID tags
AssigneesFraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V., Friedrich-Alexander-Universitaet Erlangen-Nuernberg
InventorsHazem Elsaid Ibrahim, Hamed Kenawy, Joerg Robert, Albert Heuberger, Wolfram Strauss
Life of this patent
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Abstract
An RFID reader includes a transmitter, a receiver, and an evaluator. The receiver receives signals from RFID tags within a given number of slots of a time frame with a given frame size and provides a number of successful slots and a number of collided slots. The evaluator sets a modified frame size based on an estimated number of RFID tags which is determined based on the frame size, the number of successful slots, and the number of collided slots. The invention also refers to a corresponding method.
Claims6
A Radio Frequency Identification (RFID) reader,
- comprising a transmitter configured for transmitting a request signal, a receiver configured for receiving signals from Radio Frequency Identification (RFID) tags and an evaluator,
- wherein the receiver is configured to receive the signals from the RFID tags within a given number of slots of a time frame with a given frame size,
- wherein the receiver is configured to provide a number of successful slots in which one signal has been received and a number of collided slots in which a detection of one single signal was not possible,
- wherein the evaluator is configured to set a modified frame size based on an estimated number of RFID tags,
- wherein the evaluator is configured to determine the estimated number of RFID tags based on the given frame size, the number of successful slots, and the number of collided slots,
- wherein the receiver is configured to perform a collision recovery by identifying a signal within a slot comprising more than one signal,
- wherein the receiver is configured to obtain a collision recovery probability α at which the collision recovery is performed by the receiver,
- wherein the receiver is configured to provide, in the provision, the number of successful slots, ss, and the number of collided slots, cs, after performing the collision recovery, and
- wherein the evaluator is configured to determine the estimated number of RFID tags based on the given frame size L, the number of successful slots ss, the number of collided slots cs, and the collision recovery probability α by calculating the number of collided slots before the collision recovery, Cb, and the number of successful slots before the collision recovery, Sb, according to Sb=ss−α/(1−α)*C, and Cb=cs/(1 −α) and determining the estimated number of RFID tags based on the given frame size L, the number of the collided slots Cb, and the number of the successful slots Sb.
6 more elements
A Radio Frequency Identification (RFID) reader,
- comprising a transmitter configured for transmitting a request signal, a receiver configured for receiving signals from Radio Frequency Identification (RFID) tags and an evaluator,
- wherein the receiver is configured to receive the signals from the RFID tags within a given number of slots of a time frame with a given frame size,
- wherein the receiver is configured to provide a number of successful slots in which one signal has been received and a number of collided slots in which a detection of one single signal was not possible,
- wherein the evaluator is configured to set a modified frame size based on an estimated number of RFID tags,
- wherein the evaluator is configured to determine the estimated number of RFID tags based on the given frame size, the number of successful slots, and the number of collided slots,
- wherein nest is the estimated number of RFID tags,
- wherein L is the given frame size,
- wherein cs is the number of collided slots,
- wherein ss is the number of successful slots,
- wherein said evaluator is configured to determine the estimated number of RFID tags using the following formula:
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244 more elements
A Radio Frequency Identification (RFID) reader,
- comprising a transmitter configured for transmitting a request signal, a receiver configured for receiving signals from Radio Frequency Identification (RFID) tags and an evaluator,
- wherein the receiver is configured to receive the signals from the RFID tags within a given number of slots of a time frame with a given frame size,
- wherein the receiver is configured to provide a number of successful slots in which one signal has been received and a number of collided slots in which a detection of one single signal was not possible,
- wherein the evaluator is configured to set a modified frame size based on an estimated number of RFID tags,
- wherein the evaluator is configured to determine the estimated number of RFID tags based on the given frame size, the number of successful slots, and the number of collided slots,
- wherein nest is the estimated number of RFID tags,
- wherein L is the given frame size,
- wherein cs is the number of collided slots,
- wherein ss is the number of successful slots,
- wherein α is the collision recovery probability,
- wherein the evaluator is configured to determine the estimated number of RFID tags using the following formula:
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- wherein Cb is the number of collided slots before the collision recovery performed by the receiver,
- wherein Cb is associated with the number of collided slots cs by the collision recovery probability α via:
- Cb=cs/(1−α),
- wherein Sb is the number of successful slots before the collision recovery performed by the receiver,
- wherein Sb is associated with the number of successful slots ss by the collision recovery probability α via:
- Sb=ss−α/(1−α)*C.
256 more elements
A method for recognizing at least one Radio Frequency Identification (RFID) tag, comprising:
- transmitting a request signal,
- receiving signals within a given number of slots of a time frame with a given frame size,
- providing a number of successful slots in which one signal has been received and a number of collided slots in which a detection of one single signal was not possible,
- determining an estimated number of RFID tags based on the frame size, the number of successful slots, the number of collided slots, and a collision recovery probability, and
- setting a modified frame size based on an estimated number of RFID tags,
- wherein the method further comprises
- performing a collision recovery by identifying a signal within a slot having more than one signal, and
- obtaining a collision recovery probability α at which the collision recovery is performed,
- wherein the provision provides the number of successful slots, ss, and the number of collided slots, cs, after performing the collision recovery, and
- wherein the estimated number of RFID tags is determined based on the frame size L, the number of successful slots ss, the number of collided slots cs, and the collision recovery probability α by calculating the number of collided slots before the collision recovery, Cb, and the number of successful slots before the collision recovery, Sb, according to Sb=ss−α/(1−α)*C, and Cb=cs/(1−α) and determining the estimated number of RFID tags based on the frame size, the number of the collided slots Cb, and the number of the successful slots Sb.
7 more elements
Dependencies are inferred from the claim text.