RFID Tag Verification via Delayed Read-Verify Command
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Solution Overview
Problem
In dense RFID reader environments, cross-reads occur when a signal from an RFID tag is sensed by multiple readers, leading to incorrect tag location determination, as readers may become synchronized and inadvertently read tags powered by other readers, causing uncertainty in tag location.
Innovation Solution
Implementing a delayed read verify command after tag singulation to verify the response and ensure it was received from the correctly powered tag, thereby moving readers out of synchronization and reducing cross-reads by using a reader configuration with a tag power module, a singulate module, and a read verify module to manage RF signals and commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If readers are synchronized in their attempts to singulate tags, then communication efficiency between readers and tags is improved, but cross-reads of tags occur leading to incorrect tag location determination
Solution Approach 1:
The system performs preliminary tag verification by transmitting a read-verify command after a delay period following the singulation command. This preliminary verification action checks whether the tag responds to the verifying reader before finalizing the tag location determination, thereby preventing cross-read errors while maintaining efficient reader synchronization
Solution Approach 2:
The system implements feedback by monitoring whether a tag responds to the read-verify command transmitted by the verifying reader. If the tag responds, it confirms the tag was incorrectly singulated by the verifying reader (cross-read), and the system uses this feedback information to correct the tag location determination and adjust reader synchronization accordingly
2Measurement precision
If physical layout and RF parameters are configured to reduce cross-reads, then tag location accuracy is improved, but some non-negligible cross-reads still occur over time
Solution Approach 1:
The system performs preliminary verification by transmitting read-verify commands after a delay period to check whether tags are correctly associated with their singulating readers. This preliminary action catches cross-read errors that occur despite proper physical layout and RF parameter configuration, providing an additional layer of verification that maintains reliable tag location determination over time
Solution Approach 2:
The system uses feedback from tag responses to read-verify commands to detect and correct cross-read events. When a tag responds to a verifying reader's read-verify command, the system receives feedback indicating a cross-read occurred, and uses this information to adjust reader synchronization and prevent future cross-reads, thereby maintaining consistent reliability
3Reliability
If a delayed read verify command is transmitted to verify singulated tags, then cross-reads are reduced, but additional communication time is required
Solution Approach 1:
The system applies partial verification by transmitting read-verify commands only to verifying readers (readers other than the singulating reader) after a delay period. This partial verification approach reduces cross-reads without requiring complete re-verification of all tag-reader associations, thereby limiting the additional time required while maintaining reliable cross-read reduction
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces cross-reads by verifying the response to the read verify command, ensuring accurate tag identification and location determination, thereby improving communication quality and tag read rates in RFID systems.
Implementation Method 1
Readers typically have one or more antennas transmitting radio frequency signals to which tags respond
Implementation Method 2
the reader 'interrogates' RFID tags, and receives signals back from the tags in response to the interrogation
Data Source
AI summary
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.