Interferometric Location Sensing for Indoor Angle-of-Arrival Accuracy
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Solution Overview
Problem
Existing wireless localization methods, such as GPS and cellular network triangulation, are inaccurate and unreliable in indoor and crowded urban environments.
Innovation Solution
Utilizing a method that involves receiving signals from multiple antennas at different locations, computing temporal correlation functions to identify correlation peaks and measure phase differences, and estimating angles of arrival or departure to determine the location of a wireless transmitter without establishing an association.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS is used for location determination, then outdoor location accuracy is achieved, but indoor location accuracy deteriorates
Solution Approach 1:
The patent introduces wireless access points and cellular base stations as intermediary devices to enable location determination in indoor environments. These intermediaries receive and process wireless signals, allowing location calculation without direct GPS satellite reception. The system uses the infrastructure of existing wireless networks as mediators between the mobile device and the location determination process.
2Ease of operation
If cellular network triangulation is used, then location determination is enabled, but accuracy and reliability deteriorate
Solution Approach 1:
The patent replaces traditional geometric triangulation methods with interferometric phase difference measurement. Instead of relying on signal strength-based geometric calculations, the system uses phase information from multiple antennas to determine angle of arrival, providing more accurate and reliable location data through a different physical measurement approach.
3Adaptability or versatility
If GPS dependency is maintained, then outdoor location services work, but indoor location services fail
Solution Approach 1:
The patent creates a universal location determination system that works across both outdoor and indoor environments. By using phase difference measurements from wireless infrastructure that exists in both settings, the system eliminates environmental limitations and provides consistent location services regardless of whether the device is outdoors with GPS access or indoors without satellite visibility.
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 accurate location determination of mobile transceivers relative to fixed transceivers, even in challenging environments, using existing wireless infrastructure without dependence on GPS.
Implementation Method 1
A phase difference is measured between the first and second signals based on a difference between the first and second carrier phases extracted at the first and second correlation peaks
Implementation Method 2
Interferometric location sensing
Data Source
AI summary
A method for signal processing includes receiving via first and second antennas respective first and second input signals in response to an output signal that is transmitted from a wireless transmitter and encodes a predefined sequence of symbols. A temporal correlation function is computed over the first and second input signals with respect to one or more of the symbols in the predefined sequence so as to identify respective first and second correlation peaks and extract respective first and second carrier phases of the first and second input signals at the first and second correlation peaks. A phase difference between the first and second signals is measured based on a difference between the first and second carrier phases extracted at the first and second correlation peaks. Based on the measured phase difference, an angle of arrival of the output signal from the wireless transmitter is estimated.