Impinj, Inc.

Synopsys, Inc.

Virage Logic Corporation

Alberto Pesavento

Christopher J Diorio

John D Hyde

Theron Stanford

Thomas G Anderl

Robert J Ascani

Todd E Humes

Troy N Gilliland

Harley K Heinrich

Frédéric J Bernard

Scott A Cooper

Matthew Robshaw

Kurt Eugene Sundstrom

Jay A Kuhn

Chad A Lindhorst

Joshua F Ensworth

Charles J T Peach

Vadim Lobanov

Vadim Gutnik

Shailendra Srinivas

Terry D Hass

Adrian Wojnowski

Jamie L Langlinais

Shail Srinivas

Ronald A Oliver

Yanjun Ma

Ronald Lee Koepp

William T Colleran

Kambiz Rahimi

Kaila Raby

Frederic J Bernard

Charles Peach

David D Dressler

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.

RFID tag location using inventory cycles and illumination adjustment

RFID systems may be configured to use session-dependent replies. When an RFID tag is involved in a certain inventorying session, the tag may respond to inventorying commands with a reply that is at least partly generated based on the session. For example, the tag may generate a reply with a string that has parity based on the session or includes an identifier for the session. The string may be a random number, a tag identifier or item identifier, or any other suitable data sent from the tag.

RFID systems with session-dependent replies

RFID tag ICs in a population can adjust the impedance values used to backscatter-modulate reply signals to increase the distribution or spread of backscattered signal parameters, thereby facilitating the recovery of collided tag replies. An RFID tag IC may adjust its impedance value(s) based on a reader command or independently.

Controlling RFID tag population backscatter characteristics

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.

RFID loss-prevention based on transition risk

Inventory-cycle-based RFID tag location

Portals and other chokepoints can be monitored with RFID reader systems. A portion of an RFID reader system capable of generating multiple beams can be mounted between two adjacent chokepoints such that some beams are associated with one chokepoint while other beams are associated with the other chokepoint. When replies from an item are received, the item can be associated with a chokepoint based on parameters or characteristics associated with the replies and/or the beam(s) on which the replies are received. If the detected item is moving, its movement direction through the chokepoint and/or its movement speed may also be determined.

Portal monitoring with steered-beam RFID systems

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.

Impedance-change mitigation in RFID tags

Growing community of inventors

Seattle, WA, United States of America

Alberto Pesavento