Symbol Technologies, LLC

Jens Arnold

Mohammad Soleimani

Victor Hugo Molina

Mark William Duron

Wayne E Shanks

Martin J Strzelczyk

Seok Ho Kim

Ron Boschini

Darrell Pinson

Methods, systems and apparatuses for RFID readers forming a reader network are described. In an aspect of the present invention, a plurality of RFID readers are configured to interrogate tags. Furthermore, the readers are configured to communicate with one another by transferring a token, represented by a signal. Possession of the token enables the reader to access a RF communications medium. Readers can be arranged in a ring configuration, and interconnected via wired links. A secondary token may circulate in the ring in addition to the primary token, to ensure redundancy in the system. A reader waits for a predetermined time interval before accessing the RF communications medium.

Token passing protocol for RFID systems

Methods, systems, and apparatuses for verifying singulated tags are described. A radio frequency (RF) signal is transmitted to provide power to at least one tag. A powered tag is singulated. A delay time period is waited. A read verify command is transmitted to the singulated tag. A response is received to the read verify command. The response to the read verify command is verified to determine whether it was received from the singulated tag.

Verification of singulated RFID tags by RFID readers

A method for reading and tracking radio frequency identification (RFID) tags in the presence of a noisy air channel is provided. In accordance with the method, a binary tree data structure is used to characterize a plurality of RFID tags, each of which is associated with a unique identification (ID) number. During communication between a tag reader and one or more RFID tags, the tag reader traverses the binary tree, eliminating tags from communication until one tag with a unique ID number is isolated and verified. As the binary tree is traversed, counters associated with each node in the tree are incremented based on tag matches, such that, over time, counters associated with nodes in tag-populated branches will tend to have a high value and counters associated with nodes in unpopulated tree branches will tend to have low values. Where the read process is subject to noise and the tag reader is forced make a decision at a branching node, the tag reader makes a branch prediction based on the current value of the node counters associated with each of the possible alternative branches.

Method for the efficient reading of a population of radio frequency identification tags with unique identification numbers over a noisy air channel

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Perry Hall, MD, United States of America

Jens Arnold