UWB Antenna Array for Accurate Client Location Tracking
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Solution Overview
Problem
Existing client tracking and ranging methods, such as Time of Flight (ToF) measurements, face limitations in accuracy and coverage, especially in Non-Line of Sight (NLoS) scenarios and environments with insufficient anchor deployment, leading to angle ambiguity and false location determinations.
Innovation Solution
The UWB antenna array system employs an equilateral triangular formation of omnidirectional antennas with half-wavelength spacing, providing uniform gain and low group delay variation to enhance Phase-Difference-of-Arrival (PDOA) measurements, enabling accurate client location tracking with a single anchor and reducing angle ambiguity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Time of Flight (ToF) measurements are used for client tracking, then ranging capability is provided, but accuracy deteriorates in Non-Line of Sight (NLoS) scenarios and environments with insufficient anchor deployment
Solution Approach 1:
The patent replaces Time of Flight (ToF) measurements with Phase-Difference-of-Arrival (PDOA) measurements. PDOA measures the phase difference of electromagnetic signals arriving at multiple antennas, providing angular information that enables accurate location tracking even in NLoS conditions where ToF fails. This substitution of measurement methodology directly addresses the accuracy reliability issue in challenging environments.
Solution Approach 2:
The patent transitions from measuring only distance (ToF provides radial distance information) to measuring angular information (PDOA provides angle of arrival data). By adding the angular dimension to the measurement approach, the system can determine client location based on signal arrival angles rather than just distance, enabling accurate tracking in NLoS scenarios and with minimal anchor deployment.
2Measurement precision
If traditional antenna arrays are used for PDOA measurements, then angle ambiguity occurs, but positioning accuracy deteriorates
Solution Approach 1:
The patent employs an asymmetric antenna array configuration where antennas are positioned at non-uniform intervals along the array. This asymmetric arrangement creates distinct signal propagation paths that eliminate angle ambiguity by providing unique phase difference patterns for different arrival angles. The asymmetric geometry ensures that the mapping between measured phase differences and calculated angles is one-to-one, resolving the angle ambiguity problem.
Solution Approach 2:
The patent optimizes the local spacing and positioning of individual antennas within the array to create specific geometric relationships. By carefully controlling the local quality of antenna placement (half-wavelength spacing in equilateral triangular formation), the system achieves uniform gain patterns and minimizes mutual coupling effects, thereby improving PDOA measurement precision and reducing angle ambiguity.
3Measurement precision
If multiple anchors are deployed to improve coverage, then location accuracy improves, but device complexity and deployment cost increase
Solution Approach 1:
The patent enables a single anchor with multiple antennas to perform location tracking that would traditionally require multiple anchors. The multi-antenna system at one anchor provides the angular measurement capability normally needing spatial distribution across multiple anchors. This universalization allows one anchor to fulfill the location tracking function of multiple anchors, reducing deployment complexity while maintaining accuracy.
Solution Approach 2:
The patent combines the functions of multiple anchors into a single anchor by integrating multiple antennas with half-wavelength spacing in an equilateral triangular formation. This merging consolidates what would traditionally be distributed across multiple separate anchor devices into one unified anchor unit, reducing system complexity and deployment requirements while preserving location tracking accuracy through combined PDOA measurements.
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 configuration improves the accuracy of client location tracking and ranging by reducing error variance and angle ambiguity, achieving precise positioning even in challenging environments with a single anchor, while maintaining adequate link budget and coverage.
Implementation Method 1
A PDOA between the first antenna and the second antenna is determined based on the poll signal. A first portion of a final signal is received via the first antenna and a third antenna and a second portion of the final signal is received via the second antenna and the third antenna. A PDOA between the first antenna and the third antenna is determined based on the first portion of the final signal, and a PDOA between the second antenna and the third antenna is determined based on the second portion of the final signal.
Data Source
AI summary
Ultra-Wideband (UWB) ranging and location tracking, and particularly an UWB antenna array system and methods for improving the accuracy for Phase-Difference-of-Arrival (PDOA) is provided. UWB ranging may include receiving a poll signal from a client via a first and second antenna. PDOA between the first and second antenna is determined based on the poll signal. A response signal is transmitted to the client, and a first portion of a final signal is received via the first antenna and a third antenna and a second portion of the final signal is received via the second and third antenna. PDOA between the first and third antenna is determined based on the first portion, and PDOA between the second and third antenna is determined based on the second portion. The client location is then determined based on the PDOAs.