RFID Tag Localization Using Constructive Interference Mapping
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Solution Overview
Problem
Current RFID tag locating systems in indoor environments suffer from cost and usability issues, particularly with UHF RFID tags, as methods like TDOA, PDOA, and RSSI measurement face accuracy challenges.
Innovation Solution
The system employs sub-threshold superposition response mapping (STSRM) using multiple antennas to create constructive and destructive interference patterns, adjusting signal power and phase to activate RFID tags only in specific areas, combined with environmental and structural interference compensation, and utilizes a system controller for precise tag location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional locating methods (TDOA, PDOA, RSSI) are used for RFID tags, then system implementation is straightforward, but location accuracy is insufficient
Solution Approach 1:
The patent changes the fundamental parameter of signal interaction by introducing controlled destructive interference between multiple antenna signals. By adjusting signal phases and amplitudes to create destructive interference patterns, the system achieves high-precision location through the spatial distribution of interference nulls rather than traditional signal strength or time-based measurements.
Solution Approach 2:
The patent uses destructive interference patterns as an intermediary mechanism between the transmitted signals and location determination. The interference pattern acts as a mediator that transforms the raw signal data into spatial information, enabling precise location without requiring complex signal processing algorithms.
2Measurement precision
If multiple antennas are used to create interference patterns, then location precision improves, but signal processing complexity increases
Solution Approach 1:
The patent converts the potentially harmful effect of signal interference into a beneficial location determination mechanism. Instead of treating interference as noise to be filtered, the system deliberately creates and exploits destructive interference patterns as the primary source of location information, transforming a problematic phenomenon into the solution.
Solution Approach 2:
The patent replaces complex signal processing algorithms with a more straightforward interference pattern recognition approach. By substituting computational complexity with physical interference phenomena, the system achieves precise location through the natural properties of wave interference rather than through complex digital signal analysis.
3Measurement precision
If sub-threshold superposition response mapping is used, then location accuracy increases, but the number of iterations required increases
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing interference pattern maps that correspond to different signal configurations. During actual operation, the system queries these pre-computed maps rather than performing iterative calculations in real-time, significantly reducing search time while maintaining high accuracy.
Solution Approach 2:
The patent creates a copy of the interference pattern characteristics in the form of lookup tables or maps. Instead of repeatedly performing complex interference calculations during location determination, the system uses these pre-generated copies (maps) to quickly identify tag positions, reducing computational iterations.
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
STSRM achieves high-precision RFID tag localization with reduced iterations, enhancing accuracy and reducing search time, and can be integrated with other locating techniques for improved performance.
Implementation Method 1
transmitting a plurality of sub-threshold radio-frequency identification signals to create a constructive interference pattern within the predefined area
Data Source
AI summary
A system and method for locating radio-frequency identification tags within a predetermined area. The method can incorporate sub-threshold superposition response mapping techniques, alone, or in combination with other methods for locating radio-frequency identification tags such as but not limited to time differential on arrival (TDOA), frequency domain phase difference on arrival (FD-PDOA), and radio signal strength indication (RSSI). The system can include a plurality of antennas dispersed in a predefined area; one or more radio-frequency identification tags; a radio-frequency transceiver in communication with said antennas; a phase modulator coupled to the radio-frequency transceiver; and a system controller in communication with said transceiver and said phase modulator. Calibration techniques can be employed to map constructive interference zones for improved accuracy.