Abstract: Techniques are provided to estimate the location of an RFID tag using tag read information, such as a tag read count or a tag read rate, and an opportunity metric, such as an inventory cycle duration, inventory cycle rate, or inventory cycle count. A tag tracking system determines read information for a tag in a zone and an opportunity metric associated with the tag and the zone. The tag tracking system then computes a success rate based on the tag read information and opportunity metric, and uses the success rate to estimate the location of the tag.

Abstract: Synthesized-beam RFID readers may be used to locate RFID tags. In one embodiment, a tag's response rates on different beams can be used, along with the target locations of those beams, to estimate the tag's location. The estimated tag location is within a region where beams with nonzero tag response rates overlap, and the distances of the estimated tag location from any two different beam target locations may correspond to a ratio of tag response rates on the two different beams. In another embodiment, a tag's response rates on different beam pairs configured to cooperatively power RFID tags can be used, along with the target locations of those beam pairs, to estimate the tag's location.

Abstract: Embodiments are directed to restricting access to Radio Frequency Identification (RFID) tag information based on location. Access to RFID tag information may be restricted at the reader level, at the requester level, and at the network level. When reader-level restrictions exist, devices may be prevented from inventorying tags and retrieving information from tags. When requester-level restrictions exist, a requester or device may be prevented from receiving tag information from inventoried tags or a network. When network-level restrictions exist, a network may discard or otherwise restrict tag information received from devices.

Abstract: Synthesized-beam RFID readers may be used to locate RFID tags. In one embodiment, a tag's response rates on different beams can be used, along with the target locations of those beams, to estimate the tag's location. The estimated tag location is within a region where beams with nonzero tag response rates overlap, and the distances of the estimated tag location from any two different beam target locations may correspond to a ratio of tag response rates on the two different beams. In another embodiment, a tag's response rates on different beam pairs configured to cooperatively power RFID tags can be used, along with the target locations of those beam pairs, to estimate the tag's location.

Abstract: A cryptographically-enabled RFID tag stores a primary secret key and derives secondary keys from the primary key. A secondary key may be derived by combining the primary key with one or more other parameters using one or more algorithms. The tag uses a derived secondary key to encrypt or electronically sign a tag response sent to a verifying entity. The verifying entity does not know the derived secondary key, but knows the tag primary key and the parameters and algorithms used to derive the secondary key and can derive all of the potential secondary keys. The verifying entity can then attempt to authenticate the tag or tag response by trying potential secondary keys.

Abstract: Embodiments are directed to mitigating power-based impedance changes in Radio Frequency Identification (RFID) tags. The intrinsic impedance of components in an RFID tag front-end may change as incident RF power on the tag changes, causing the input impedance of the front-end to change and altering the RF properties of the RFID tag. A number of approaches can be used to mitigate input impedance variations due to power variations. One approach involves adjusting the operating point of one or more components in the RFID tag front-end to change their intrinsic impedances so as to counteract or mitigate the RF-power-based input impedance variation.

Abstract: An RFID loss-prevention system (LPS) permits authorized items to leave a facility and may perform a security action if an unauthorized item leaves the facility. A checkout reader first authorizes an item tagged with an RFID tag to exit a facility by reading an identifier from the tag, obtaining an exit authorization, and sending the identifier to a database. A reader system configured to direct at least two beams along a facility exit path reads tagged items exiting the facility, determines at least one of a travel direction and a tag location, and uses the determination to indicate that a tag is exiting or has exited the facility. The LPS then uses the database to determine if the exiting/exited tag is authorized to leave the facility.

Abstract: Techniques are provided to estimate the location of an RFID tag using tag read information, such as a tag read count or a tag read rate, and an opportunity metric, such as an inventory cycle duration, inventory cycle rate, or inventory cycle count. A tag tracking system determines read information for a tag in a zone and an opportunity metric associated with the tag and the zone. The tag tracking system then computes a success rate based on the tag read information and opportunity metric, and uses the success rate to estimate the location of the tag.

Abstract: An RFID loss-prevention system (LPS) may monitor RFID-tagged items in a facility. An RFID reader transmits a first inventory command configured to cause tags in a first state to respond, receive a reply from a first tag, determine that the first tag has a low transition risk, and cause the first tag to switch to a second state. The reader may also receive a reply from a second tag, determine that the second tag has a high transition risk, and cause the second tag to remain in the first state. The reader may then transmit a second inventory command configured to cause tags in the first state to respond, receive a reply from the second tag in response to the second inventory command, determine that the second tag has inappropriately exited the facility, and issue an alert.

Abstract: Synthesized-beam RFID readers may be used to locate RFID tags. In one embodiment, a tag's response rates on different beams can be used, along with the target locations of those beams, to estimate the tag's location. The estimated tag location is within a region where beams with nonzero tag response rates overlap, and the distances of the estimated tag location from any two different beam target locations may correspond to a ratio of tag response rates on the two different beams. In another embodiment, a tag's response rates on different beam pairs configured to cooperatively power RFID tags can be used, along with the target locations of those beam pairs, to estimate the tag's location.

Abstract: Synthesized-beam RFID readers may be used to manage and provide information about RFID tag populations. In one embodiment, two or more synthesized-beam readers synthesize respective RF beams towards a tag location. The synthesized-beam readers may coordinate their pointing by means of a controller, a peer-to-peer network, or by using a master-slave arrangement. The synthesized-beam readers may coordinate their transmissions to increase the RF energy available to a tag at the pointing location.

Abstract: Data stored in nonvolatile memory on a Radio Frequency Identification (RFID) tag integrated circuit may have a “margin” associated with how strongly the data is written to the memory. Upon receiving a wireless margin read command, the RFID IC determines whether the margin for one of more data values stored in memory exceeds a margin threshold. The IC may determine the margin by applying bias voltages or currents to the memory cells storing the data values. If the determined margin does not exceed the margin threshold, the IC may respond with an error code.

Abstract: A cryptographically-enabled RFID tag stores a primary secret key and derives secondary keys from the primary key. A secondary key may be derived by combining the primary key with one or more other parameters using one or more algorithms. The tag uses a derived secondary key to encrypt or electronically sign a tag response sent to a verifying entity. The verifying entity does not know the derived secondary key, but knows the tag primary key and the parameters and algorithms used to derive the secondary key and can derive all of the potential secondary keys. The verifying entity can then attempt to authenticate the tag or tag response by trying potential secondary keys.

Abstract: Synthesized-beam RFID readers may be used to manage and provide information about RFID tag populations. In one embodiment, two or more synthesized-beam readers synthesize respective RF beams towards a tag location. The synthesized-beam readers may coordinate their pointing by means of a controller, a peer-to-peer network, or by using a master-slave arrangement. The synthesized-beam readers may coordinate their transmissions to increase the RF energy available to a tag at the pointing location.

Abstract: An RFID loss-prevention system (LPS) permits authorized items to leave a facility and may perform a security action if an unauthorized item leaves the facility. A checkout reader first authorizes an item tagged with an RFID tag to exit a facility by reading an identifier from the tag, obtaining an exit authorization, and sending the identifier to a database. A reader system configured to direct at least two beams along a facility exit path reads tagged items exiting the facility, determines at least one of a travel direction and a tag location, and uses the determination to indicate that a tag is exiting or has exited the facility. The LPS then uses the database to determine if the exiting/exited tag is authorized to leave the facility.

Abstract: Synthesized-beam RFID readers may be used to manage and provide information about RFID tag populations. In one embodiment, two or more synthesized-beam readers synthesize respective RF beams towards a tag location. The synthesized-beam readers may coordinate their pointing by means of a controller, a peer-to-peer network, or by using a master-slave arrangement. The synthesized-beam readers may coordinate their transmissions to increase the RF energy available to a tag at the pointing location.

Abstract: An RFID loss-prevention system (LPS) based on synthesized-beam readers (SBRs) permits authorized items to leave a facility and may perform a security action if an unauthorized item leaves the facility. A checkout reader first authorizes an item tagged with an RFID tag to exit a facility by reading an identifier from the tag, obtaining an exit authorization, and sending the identifier to a database. An SBR configured to direct at least two beams along a facility exit path reads tagged items exiting the facility, determines at least one of a travel direction and a tag location, and uses the determination to indicate that a tag is exiting or has exited the facility. The LPS then uses the database to determine if the exiting/exited tag is authorized to leave the facility.

Abstract: RFID tag ICs employ tunneling-voltage profile calibration during IC manufacturing to determine and store, typically in nonvolatile memory, a tunneling-voltage profile for writing data to the IC's nonvolatile memory. The IC may subsequently read the profile at power-up, prior to writing the memory, or at other times as determined by the IC or by an interrogating reader, and may determine an actual ramp profile for writing to the nonvolatile memory based on the read profile and one or more operating conditions. By using the read profile to determine an actual ramp profile for writing to the nonvolatile memory, the IC may reduce nonvolatile memory write time and oxide stress.

Abstract: RFID tag ICs employ tunneling-voltage profile calibration during IC manufacturing to determine and store, typically in nonvolatile memory, a tunneling-voltage profile for writing data to the IC's nonvolatile memory. The IC may subsequently read the profile at power-up, prior to writing the memory, or at other times as determined by the IC or by an interrogating reader. By using the stored profile when writing to the nonvolatile memory the IC may reduce nonvolatile memory write time and oxide stress.

Abstract: A nonvolatile memory cell is constructed using a floating-gate pFET readout transistor having its source tied to a power source (Vdd) and its drain providing a current, which can be sensed to determine the state of the cell. The gate of the pFET readout transistor provides for charge storage, which can be used to represent information such as binary bits. A control capacitor coupled between a first voltage source and the floating gate and a tunneling capacitor between a second voltage source and the floating gate are fabricated so that the control capacitor has much more capacitance than the tunneling capacitor. Manipulation of the voltages applied to the first voltage source and second voltage source controls an electric field across the capacitor structure and pFET dielectrics and thus Fowler-Nordheim tunneling of electrons on and off the floating gate, controlling the charge on the floating gate and the information stored thereon.