Passive RFID Antenna Localization Using TDOA-FDOA Correlation
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Solution Overview
Problem
Conventional radio frequency identification (RFID) systems, particularly long-range RFID systems, face limitations in operational range, making them unsuitable for search and rescue operations where powered emitters may not be feasible and passive emitters lack sufficient range, especially in large-scale events.
Innovation Solution
A correlative receiver system utilizing multiple antennas to calculate time and frequency differences of arrival (TDOA and FDOA) values, generating correlation maps, and averaging these to locate RFID antennas, which can be unpowered, by identifying maximum correlation values on combined maps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional RFID systems are used, then device localization is possible, but the operational range is limited
Solution Approach 1:
The system segments the localization problem into multiple measurement components (TDOA from multiple antenna pairs, FDOA from frequency shifts) and combines them through correlation mapping to achieve both extended range and maintained precision
Solution Approach 2:
The patent introduces a correlation domain as an additional dimension for analysis. By transforming spatial domain signals into correlation maps with TDOA and FDOA axes, the system extends the effective operational range while maintaining localization precision through multi-dimensional correlation analysis
2Power
If powered emitters are used, then signal generation capability is improved, but power availability becomes a constraint
Solution Approach 1:
The RFID antenna serves itself by generating return signals through passive reflection and modulation of the incident signal, eliminating the need for an external power source while maintaining signal generation capability for localization purposes
Solution Approach 2:
The incident signal from the external transmitter acts as an intermediary, providing the energy needed to generate return signals from the passive RFID antenna, thereby enabling signal generation without direct power supply to the antenna
3Use of energy by moving object
If passive emitters are used, then power consumption is reduced, but signal range becomes insufficient
Solution Approach 1:
The system merges TDOA and FDOA measurements from multiple antenna pairs into a unified correlation map, combining multiple weak signals and measurements to achieve extended effective range while maintaining passive operation
Solution Approach 2:
By transforming the problem into the correlation domain with TDOA and FDOA dimensions, the system extends the effective range of passive emitters through multi-dimensional signal processing and correlation analysis
4Measurement precision
If multiple antennas are deployed, then localization accuracy is improved, but system complexity increases
Solution Approach 1:
The system segments the complex multi-antenna signal processing into modular correlation maps for each antenna pair, where each map independently processes TDOA and FDOA measurements, reducing overall computational complexity while maintaining high localization accuracy
Solution Approach 2:
By transforming spatial correlation problems into TDOA-FDOA correlation maps, the system simplifies the integration of multiple antenna measurements, making the combination of data from multiple antennas more manageable and less complex
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
Enables the precise localization of RFID antennas over extended distances, even in unpowered devices, enhancing the effectiveness of search and rescue operations by leveraging computational correlation rather than relying on conventional reader transmitters.
Implementation Method 1
A signal emitted by a transmitter can cause an unpowered mobile device's RFID antenna to generate return signals
Implementation Method 2
Time difference of arrival (TDOA) and frequency difference of arrival (FDOA) values can be calculated for the received signals
Implementation Method 3
Time difference of arrival (TDOA) and frequency difference of arrival (FDOA) values can be calculated for the received signals
Implementation Method 4
The calculated TDOA and FDOA values can be correlated using a cross-ambiguity function (CAF). The correlated values can be plotted on a map to create a set of correlation maps. The correlation maps can be combined to produce an average map and the antenna can be located by identifying a maximum correlation value on the average map
Data Source
AI summary
Embodiments of the present disclosure utilize signals generated by a radio frequency identification (RFID) antenna to locate the antenna. For example, a signal emitted by a transmitter can cause an unpowered mobile device's RFID antenna to generate return signals that are received by multiple antennas. Time difference of arrival (TDOA) and a frequency difference of arrival (FDOA) values can be calculated for the received signals. The calculated TDOA and FDOA values can be correlated using a cross ambiguity function (CAF). The correlated values can be plotted on a map to create a set of correlation maps. The correlation maps can be combined to produce an average map and the antenna can be located by identifying a maximum correlation value on the average map.