Wireless Terminal Location via Barometric Pressure Wave Analysis
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Solution Overview
Problem
Existing location estimation techniques for wireless terminals are unreliable in environments with signal obstructions and indoors, where signal impairment is subtle and difficult to detect, leading to inaccurate location estimates that can have serious consequences for emergency services.
Innovation Solution
A location engine that estimates whether a wireless terminal is indoors or outdoors by analyzing barometric pressure measurements, using the correlation between transient pressure waves and indoor environments to infer the location based on the presence or absence of specific pressure wave features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal-based location estimation techniques are used, then location can be estimated in open environments, but reliability deteriorates in indoor environments with signal obstructions and impairment
Solution Approach 1:
The patent introduces barometric pressure measurements as an intermediary parameter to detect indoor environments. The pressure sensor acts as a mediator that detects transient pressure waves caused by door openings/closings, providing indirect evidence of indoor location without relying on impaired radio signals. This intermediary measurement resolves the contradiction by enabling reliable location estimation in indoor environments where traditional signal-based methods fail.
Solution Approach 2:
The patent replaces the electromagnetic signal-based location estimation system with a mechanical pressure-based detection system. Instead of relying on radio wave propagation characteristics that are impaired by buildings and obstacles, the system uses barometric pressure measurements to detect indoor environments. This substitution resolves the technical contradiction by using a physical mechanism (pressure waves) that is not affected by the same obstructions that impair electromagnetic signals.
2Measurement precision
If traditional signal measurement techniques are used, then location estimation can be performed, but measurement precision deteriorates when signals are weak or impaired
Solution Approach 1:
The patent uses barometric pressure as an intermediary measurement that is not affected by signal impairment. The pressure sensor detects transient pressure waves in the air, providing a separate measurement channel that is independent of radio signal quality. This intermediary measurement allows the system to achieve precise location estimation even when traditional signal measurements are degraded by obstructions, attenuation, or indoor environmental factors.
Solution Approach 2:
The patent changes the measurement parameter from electromagnetic signal strength to barometric pressure. By measuring pressure variations caused by door openings and closings, the system obtains location information that is not subject to the same harmful factors affecting radio signals. This parameter change resolves the contradiction by using a physical quantity (pressure) that maintains measurement precision regardless of signal impairment conditions.
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 solution provides accurate location estimates by distinguishing between indoor and outdoor environments through detectable transient pressure waves, improving reliability and reducing errors in location determination, especially in challenging environments like buildings.
Implementation Method 1
generating a characterization of a pressure wave in the vicinity of the wireless terminal based on the sample of barometric pressure measured at the wireless terminal
Data Source
AI summary
A method for estimating the location of a wireless terminal at an unknown location, such as within a building. A location engine using the disclosed method receives and uses samples of barometric pressure measured by the wireless terminal to generate a characterization of a pressure wave in the vicinity of the wireless terminal. The location engine generates an estimate of the location of the wireless terminal based on the characterization of the pressure wave and, in some cases, the location of the source of the pressure wave, such as a building's door that is opening or closing. The location engine also bases the estimate of the wireless terminal's location on a propagation characteristic of the pressure wave, such as its speed of propagation.