Wireless Localisation Using Round Trip Distance and Phase
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Solution Overview
Problem
Conventional wireless positioning systems using time-of-arrival (ToA) or direction-of-arrival (DoA) measurements require multiple fixed anchor nodes, making them unsuitable for scenarios with a single nomadic master node, and existing joint ToA/DoA-based methods are computationally intensive, which is impractical for real-world applications.
Innovation Solution
A wireless positioning system employing a single nomadic master node with an antenna array that measures round trip distances and phase of signals to estimate the location of mobile nodes using a least squares method, reducing computational burden and ambiguity in phase measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If joint ToA/DoA-based positioning is used with a single master node, then positioning functionality is achieved, but computational complexity becomes too high for practical implementation
Solution Approach 1:
The patent segments the positioning problem into two separate measurement components: round trip distance (RTD) measurements from multiple antenna elements and phase difference measurements. By dividing the complex joint estimation into separate measurable quantities that can be processed independently, the computational burden is significantly reduced while maintaining positioning functionality with a single master node.
Solution Approach 2:
The patent replaces the computationally intensive maximum-likelihood estimation mechanism with a geometry-based calculation approach. Instead of performing complex iterative optimization to jointly estimate ToA and DoA, the system uses closed-form geometric relationships between RTD measurements, phase differences, and antenna element positions to directly compute target location, thereby substituting mechanical computation with mathematical geometry.
2Measurement precision
If multiple fixed anchor nodes are used for ToA or DoA measurements, then positioning accuracy is improved, but system adaptability to single-node scenarios is lost
Solution Approach 1:
The patent makes the single master node universal by enabling it to perform functions traditionally requiring multiple anchor nodes. The master node uses its multiple antenna elements to simultaneously perform ToA measurement (via RTD) and DoA measurement (via phase difference), making the single node capable of achieving positioning accuracy comparable to multi-node systems while maintaining adaptability to single-node deployment scenarios.
Solution Approach 2:
The patent adds the spatial dimension of multiple antenna elements at the single master node to compensate for the absence of multiple anchor nodes. By utilizing the spatial separation between antenna elements, the system creates virtual baseline measurements that provide the geometric diversity needed for accurate positioning, effectively transforming a single-point node into a multi-point equivalent through spatial dimensionality.
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
The system achieves greater accuracy and reduced computational cost for estimating mobile node locations, making it more practical for applications like tracking workers in a worksite environment.
Implementation Method 1
the first wireless signal is used to measure a first time of arrival between the apparatus and the remote node and the second wireless signal is used to measure a second time of arrival between the remote node and the apparatus
Implementation Method 2
each receiving element is configured to measure the phase of the second wireless signal relative to a common reference phase
Data Source
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AI summary
Disclosed is an apparatus for estimating the location of a remote node. The apparatus comprises an antenna array comprising a plurality of elements in a fixed spatial arrangement, at least one element being a transmitting element configured to transmit a first wireless signal to the remote node, and at least two elements being receiving elements configured to receive a second wireless signal transmitted by the remote node in response to the first wireless signal. The apparatus further comprises a signal processing unit connected to the antenna array, the signal processing unit being configured to: estimate a plurality of round trip distances using the wireless signals, each round trip distance being from a transmitting element to the remote node and back to a receiving element; and estimate the location of the remote node using the round trip distance estimates.