RFID Phase Pattern Matching for Multipath Localization
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Solution Overview
Problem
Current RFID phase-based localization techniques are impractical for real-world applications due to noise susceptibility and environment change sensitivity, making it challenging to accurately determine the location of RFID tags in multipath environments.
Innovation Solution
The proposed solution involves extracting a robust and stable phase signal pattern from RFID signals, using pattern matching techniques such as cosine similarity, and leveraging fixed location reference tags to estimate the location of RFID tagged items or people, rather than relying on absolute phase values for distance calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If absolute phase values are used for distance calculation in RFID localization, then the localization method is simple to implement, but the measurement precision deteriorates due to noise susceptibility and environment change sensitivity
Solution Approach 1:
The patent performs preliminary calibration by measuring phase values at multiple known distances and storing them as reference data before actual localization. This pre-established reference database enables accurate localization without directly calculating absolute phase-to-distance conversions, thereby avoiding noise and environmental sensitivity issues while maintaining implementation simplicity.
Solution Approach 2:
The patent creates a reference copy of phase patterns at known distances and uses pattern matching against this reference database. Instead of directly using absolute phase values for distance calculation, it compares the current phase pattern with stored reference patterns, achieving high precision localization through pattern recognition rather than direct mathematical conversion.
2Adaptability or versatility
If phase-based localization techniques are applied in multipath environments, then RFID technology can provide location tracking capability, but the reliability deteriorates due to multipath effects and RF signal sensitivity
Solution Approach 1:
The system performs preliminary measurements in the specific multipath environment to capture the characteristic phase patterns including multipath effects. By storing these environment-specific reference patterns, the system adapts to the multipath conditions and achieves reliable localization despite the challenging RF environment.
Solution Approach 2:
The patent converts the harmful multipath effects into a useful characteristic by capturing the complete phase pattern including multipath contributions during calibration. The multipath signals, which normally cause errors in absolute phase measurement, become part of the reference pattern that is matched during localization, thereby transforming the reliability problem into a solution.
3Measurement precision
If pattern matching with reference phase patterns is used, then the localization accuracy is improved in multipath environments, but the device complexity increases due to calibration requirements and pattern storage
Solution Approach 1:
The system performs self-calibration by automatically measuring phase values at known distances and generating its own reference database without requiring external intervention or complex configuration. This self-service approach simplifies deployment while achieving high accuracy through pattern matching.
Solution Approach 2:
The patent changes the approach from using absolute phase values to using relative phase patterns and their derivatives. By transforming the measurement from absolute to relative parameters and using pattern recognition instead of direct calculation, it achieves high accuracy while keeping the system complexity manageable through software-based pattern matching.
Data Source
AI summary
A method for localizing a device. The method is performed by a communication device. The method includes measuring a phase of a signal that the communication device has received from the device, the signal having a first frequency; measuring a phase of at least one further signal that the communication device has received from the device; the at least one further signal having a second frequency, determining a phase pattern of a measured phase versus frequency, pattern matching the phase pattern with each reference phase pattern of a plurality of pre-determined reference phase patterns. Each reference phase pattern is associated with a distance between the communication device and the further communication device. The method further includes determining the distance between the further communication device and the communication device based on the pattern matching.