RFID Tag Localization Using Synchronized Phase-Based Ranging
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Solution Overview
Problem
Existing RFID systems face challenges in accurately determining the contents of a container or item inventory with low location and ranging accuracy, particularly in densely populated environments, leading to incorrect inclusion or exclusion of RFID tagged items.
Innovation Solution
Implement phase-based ranging (PBR) using synchronized frequency hopping sequences with multiple RFID reader devices to estimate distances and localize RFID tags, utilizing a location estimation engine to analyze distance measurements from multiple readers at known locations, and employing fixed reference tags for calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional RFID reading methods are used, then the system is simple and easy to operate, but the location and ranging accuracy is low leading to incorrect inclusion or exclusion of RFID tagged items
Solution Approach 1:
The patent changes the measurement parameter from simple signal presence detection to phase-based distance estimation. By measuring the phase of the backscatter signal at multiple frequency points and using phase unwrapping algorithms, the system achieves precise distance measurements. This parameter transformation enables accurate localization while maintaining RFID system operation
Solution Approach 2:
The patent introduces fixed reference tags as intermediary elements to establish known distance benchmarks. These reference tags placed at known positions serve as mediators between the RFID readers and the items being tracked, enabling the system to calculate accurate distances and locations through comparison with the known reference positions
2Measurement precision
If multiple RFID reader devices are deployed to improve localization accuracy, then the location estimation precision improves, but the device complexity and synchronization requirements increase
Solution Approach 1:
The patent implements periodic frequency hopping where multiple RFID readers sequentially access different frequency points in a synchronized cycle. Each reader hops through predefined frequency sequences at regular intervals, allowing the system to collect phase measurements across multiple frequencies from multiple readers without continuous interference. This periodic structure simplifies the coordination complexity while enabling accurate multi-reader localization
Solution Approach 2:
The patent performs preliminary synchronization of frequency hopping sequences before actual measurement begins. The system pre-configures the frequency hopping patterns and timing for all readers, establishing a known reference framework in advance. This preliminary action reduces the complexity during actual operation by eliminating the need for real-time negotiation and coordination between readers
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
Enhances RFID tag localization accuracy in two or three dimensions, enabling precise determination of container contents and item inventory without prior knowledge of the subset of interest, improving selective reading and localization of RFID tags.
Implementation Method 1
a backscatter signal received from the RFID tag
Data Source
AI summary
Systems and techniques are provided for wireless communications. A wireless communication device can obtain information indicative of a configured sequence of carrier frequencies associated with phase-based ranging (PBR) distance estimation between the wireless communication device and a Radio Frequency Identification (RFID) tag. An RFID Query command transmitted from a first RFID reader device to the RFID tag can be detected. A pilot tone can be sequentially transmitted to the RFID tag on each respective carrier frequency of the configured sequence, using a corresponding plurality of frequency hops synchronized between at least the wireless communication device and the first RFID reader device. A PBR measurement can be determined, indicative of an estimated distance from the wireless communication device to the RFID tag based on relative phase measurement associated with a backscatter signal received from the RFID tag for each respective carrier frequency of the configured sequence of carrier frequencies.