RF Backscatter Tag Localization via Simultaneous Multi-Port Reception
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Solution Overview
Problem
Current RFID systems face challenges in efficiently reading a large number of passive RFID tags due to tag collisions and interference, leading to delayed responses and hidden tags in crowded environments, despite collision avoidance schemes like the RFID Gen II Standard.
Innovation Solution
The implementation of Simultaneous Multi-Port (SMP) reception using synchronized RF backscatter transmitters and receivers with dual-mode antennas, along with spatial reuse and time splitting techniques, to manage tag responses and reduce interference by partitioning the reading area into smaller volumes and controlling tag excitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If collision avoidance schemes like RFID Gen II Standard are used, then tag reading capability is improved, but in crowded environments with large population of RFID tags, replies become delayed and collisions still cause some tags to remain hidden
Solution Approach 1:
The patent divides the reading area into multiple zones and segments tag reading into different time slots. By spatially separating tags into zones and temporally separating their responses, the system reduces collisions and hidden tag problems in crowded environments while maintaining reading capability.
Solution Approach 2:
The patent implements periodic time-slot-based tag excitation and response collection. Tags are excited in periodic intervals with different time slots assigned to different zones, allowing systematic reading of crowded tags without mutual interference, thus reducing response delays.
2Area of stationary object
If multiple RFID tags are in the range of a given reader, then coverage area is improved, but their replies interfere and cause mis-detection
Solution Approach 1:
The patent segments the reading area into multiple zones with dedicated time slots. This spatial-temporal segmentation allows the system to maintain large reading coverage while preventing signal interference by processing tags in different zones at different times.
Solution Approach 2:
The patent introduces time slots as an intermediary mechanism between tags in different zones. By mediating tag responses through time-division multiplexing, the system enables large-area coverage while maintaining detection accuracy through controlled sequential reading.
3Reliability
If collision avoidance schemes are implemented, then system robustness is improved, but tag reading time increases due to delayed responses
Solution Approach 1:
The patent uses periodic time-slot-based tag excitation that systematically cycles through different zones. This periodic approach maintains system robustness through controlled collision avoidance while improving reading efficiency by parallelizing tag access across multiple zones in each period.
Solution Approach 2:
The patent implements continuous tag reading across multiple zones by eliminating idle time between zone readings. The systematic time-slot allocation ensures continuous useful action as each time slot is fully utilized for reading tags in its assigned zone, improving overall reading efficiency.
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 significantly reduces the time required to read RFID tags, enhances reading efficiency, and allows for accurate localization of tags in crowded environments by minimizing collisions and improving data collection rates.
Implementation Method 1
a plurality of passive RF backscatter tags, each associated with a respective product and configured to backscatter a reply in response to a transmission from the at least one RF backscatter transmitter
Data Source
AI summary
A product tagging system is provided that includes at least one RF backscatter transmitter configured to emit a Radio Frequency (RF) signal on a frequency. The system includes a plurality of passive RF backscatter tags, each associated with a respective product and configured to backscatter a reply in response to a transmission from the transmitter. The system includes at least one RF backscatter receiver configured to read data for the respective product by detecting a distributed ambient backscatter signal generated by backscattering the RF signal by a corresponding one of the tags. The at least one RF backscatter receiver includes at least two antennas for performing Simultaneous Multi-Port reception (SMP) by receiving respective distributed ambient backscatter signals from a same one of the tags responsive to a same one of the RF signal being transmitted thereto. Each of the transmitter and receiver include a respective synchronized clock for the SMP.