Device Location Accuracy via Iterative ToF Calibration
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Solution Overview
Problem
Time-of-flight-based location determination systems face challenges in accuracy due to varying delays caused by different device chipsets, leading to inconsistent time-of-flight measurements and incorrect location estimates, especially as new devices enter the market, making manual measurement burdensome and impractical.
Innovation Solution
A method to determine a device's location by estimating the chipset-induced delay (baseToF value) and iteratively refining it, using multilateration with additional access points to account for unknown errors, allowing for accurate location determination regardless of device type or manufacturer, without requiring constant updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual measurement of baseToF values is performed for each device, then measurement precision is improved, but device complexity and ease of operation deteriorate due to burdensome manual intervention
Solution Approach 1:
The system performs self-calibration by automatically determining baseToF values through iterative multilateration calculations using TOF measurements from multiple access points. The location determination system independently refines baseToF values without requiring external manual measurement, making the system self-sufficient and eliminating the burden of manual device-by-device calibration.
Solution Approach 2:
The system dynamically adjusts the baseToF parameter through iterative refinement based on multilateration results. By changing the baseToF value systematically using mathematical optimization with additional access points, the system achieves accurate location determination automatically without manual intervention for each device.
2Measurement precision
If constant updates to the location determination system are performed, then measurement precision is improved for new devices, but productivity deteriorates due to continuous maintenance requirements
Solution Approach 1:
The system automatically adapts to new devices through self-calibration using iterative multilateration. When a new device enters the market or is first connected, the system independently determines its specific baseToF value through mathematical calculations using TOF measurements from multiple access points, eliminating the need for constant manual updates or system administrator intervention.
Solution Approach 2:
The system performs preliminary calibration automatically during the initial location determination process. By incorporating iterative refinement of baseToF values as part of the standard location calculation routine, the system prepares and adjusts parameters in advance before actual location determination is needed, ensuring accuracy is maintained without continuous updates.
3Measurement precision
If iterative multilateration is performed to determine baseToF value, then measurement precision is improved, but loss of time increases due to additional calculations
Solution Approach 1:
The system performs a limited number of iterative multilateration calculations to determine baseToF value rather than exhaustive computation. By using a practical number of access points (at least four) and performing iterations only when necessary (e.g., when location estimates differ between iterations), the system achieves sufficient precision without excessive calculation time that would degrade user experience.
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 approach enhances location determination accuracy for any device, improves precision over time, and eliminates the need for manual measurement and continuous updates, ensuring reliable performance across various devices.
Implementation Method 1
time-of-flight measurements of WiFi-capable devices to estimate a distance of a device from a wireless access point
Data Source
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AI summary
Described herein are techniques for determining a location of a device. In an example, a group of access points may be selected. Time-of-flight (ToF) measurements relative to the device may be received from each of the access points in the group. A respective distance of the device from each access point may be determined using the ToF measurements and a baseToF value. Location coordinates of the device and a new baseToF value may be determined based on the determined distances and the location coordinates of each access point in the group.