Impinj, Inc.

Jayasuryan Iyer

Kurt Eugene Sundstrom

Scott A Cooper

Sandesh Doddameti

Balaji Shyamkumar

Christopher J Diorio

An RFID-based item tracking system may use statistical methods to determine whether a tag or tagged item that does not respond when inventoried is present in a particular zone or reader antenna field-of-view. In one embodiment, the item tracking system may determine an observability of an item based on one or more initial trials. Upon not detecting the item in one or more subsequent trials, the item tracking system may estimate whether the item is still present based on the observability.

RFID-based item presence detection

RFID readers may be configured to recover multiple, collided RFID tag signals. An RFID reader may receive a collided reply waveform including at least first and second tag responses. The reader may determine that the collided reply waveform contains multiple tag responses and recover the first and second tag responses from the collided reply waveform. The reader may first recover the first tag response, reconstruct the first tag response, and subtract the reconstructed first tag response from the collided reply waveform to form a modified tag response. The reader may then recover the second tag response from the modified tag response.

Weak RFID tag signal recovery from collisions

RFID readers may be configured to recover weak RFID tag signals from collisions with stronger RFID tag signals. An RFID reader may receive a combined tag response including a strong tag response and a weak tag response. The reader recovers the strong and weak tag responses using source separation. In one example, the reader may recover the strong tag response from the combined tag response and remove the recovered tag response from the combined tag response to form a modified tag response. The reader may then recover the weak tag response from the modified tag response.

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Bellevue, WA, United States of America

Jayasuryan Iyer