Access Point Signal Strength Calibration for Indoor Fingerprinting
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Solution Overview
Problem
Existing Wi-Fi-based positioning systems, particularly fingerprinting methods, face challenges in accurately determining the location of client devices indoors due to variability in signal strength measurements caused by different probe devices and the need for prolonged calibration phases, which can be time-consuming and require frequent updates.
Innovation Solution
The method involves generating a signal strength map by using a probe device to transmit probe requests and having access points detect and respond with signal strengths, which are then recorded in a fingerprinting database from the access points' perspective, providing a consistent and accurate view of signal strengths, reducing calibration time and improving positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal strength measurements are taken from the probe device's perspective, then the calibration process captures device-specific variability, but this leads to inconsistent measurements and reduced positioning accuracy
Solution Approach 1:
The patent inverts the traditional measurement perspective by having access points measure signal strength from their own perspective rather than having probe devices measure from their perspective. This inversion eliminates probe device variability and provides consistent measurements centered on the access points, directly resolving the contradiction between measurement consistency and positioning accuracy.
2Measurement precision
If traditional fingerprinting calibration is performed with multiple probe devices, then comprehensive signal data is collected, but this increases calibration time and complexity
Solution Approach 1:
The access points perform self-service by autonomously measuring signal strength from their own perspective and generating fingerprint data without requiring multiple probe devices. This self-service approach maintains comprehensive signal data collection while dramatically reducing calibration time and complexity, as each access point independently contributes to the fingerprinting database.
3Adaptability or versatility
If signal strength is measured from probe device perspective, then device-specific characteristics are captured, but this introduces variability that reduces measurement reliability
Solution Approach 1:
The patent applies inversion by switching the measurement subject from probe devices to access points. This eliminates the variability introduced by different probe devices while maintaining the ability to capture location-specific signal characteristics. The access points, being fixed infrastructure elements, provide reliable and consistent measurements that do not vary with different measuring devices.
Data Source
AI summary
Provided are devices, computer-program products, and methods for calibration of a signal strength map for purposes of providing wireless positioning services through fingerprinting. Fingerprinting involves generating a map of the signal strengths in an area covered by a Wi-Fi network. In some implementations, a wireless probe request may be received. In these implementations, the wireless probe request may be associated with location information. In some implementations, the signal strength of the wireless probe request may be detected. In these implementations, the signal strength may indicate a signal characteristic between an origination and a destination for the wireless probe request. In some implementations, the wireless probe request may be responded to with a response message. In these implementations, the response message may include the signal strength of the wireless probe request. In these implementations, the response message and the location information may further facilitate generating an entry in a fingerprinting database.