Mobile Device Sensor Displacement for Indoor RF Positioning
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Solution Overview
Problem
Traditional methods for maintaining and updating wireless positioning databases in indoor environments are costly, time-consuming, and prone to inaccuracies due to the reliance on professional surveys and the need for absolute mobile device positions, which are often unavailable in deep indoor areas where satellite fixes are unreliable.
Innovation Solution
Mobile devices measure radio signal characteristics and determine displacement data using sensors, which are then sent to a server to aid in updating the positioning database, allowing for relative positioning and crowd-sourced data collection even without known absolute positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If professional surveyors are used to collect AP location data, then positioning database accuracy is improved, but cost and time consumption increase significantly
Solution Approach 1:
The system enables mobile devices to automatically collect and report AP location data and RF measurements without requiring professional surveyors. Mobile devices use their own sensors (accelerometers, gyroscopes, magnetometers) to determine displacement and calculate device positions, then report this data to a server that builds and maintains the positioning database autonomously.
Solution Approach 2:
Instead of physically surveying each AP location with expensive equipment, the system uses multiple mobile devices to collect redundant measurements of the same environment. The server aggregates data from many devices to create an accurate positioning database, effectively copying the surveying function across numerous inexpensive devices.
2Ease of manufacture
If traditional crowdsourcing is used for RF measurements, then data collection cost is reduced, but applicability is limited in deep indoor areas where absolute positions are unknown
Solution Approach 1:
The system introduces sensor-based displacement data as an intermediary between RF measurements and absolute positioning. Mobile devices use sensors to measure relative movement and calculate displacement vectors, which serve as a mediator to establish position relationships even when GPS or other absolute positioning systems are unavailable in deep indoor environments.
Solution Approach 2:
The positioning problem is segmented into relative displacement measurements between multiple devices rather than requiring absolute positioning for each device. By collecting RF measurements and sensor data from multiple devices at different positions and combining these segmented measurements on the server, the system can solve for AP locations without needing known absolute device positions.
3Reliability
If frequent surveys are performed to track AP location changes, then positioning database currency is improved, but overhead costs increase
Solution Approach 1:
The system enables continuous, passive collection of positioning data as mobile devices naturally move through the environment. Instead of periodic active surveys, devices continuously report RF measurements and sensor data whenever they are in use, providing ongoing updates to the positioning database without requiring dedicated surveying operations.
Solution Approach 2:
Mobile devices automatically perform data collection and reporting without requiring human intervention or scheduled maintenance operations. The system self-updates the positioning database through autonomous data collection from devices that users already carry and use daily, eliminating the need for paid surveyor contracts and manual update schedules.
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 enables efficient and accurate maintenance of wireless transmitter positions within indoor environments, reducing costs and improving positioning accuracy by leveraging relative displacement data from mobile devices, even in areas with unreliable satellite signals.
Implementation Method 1
determine a displacement between the second position and the first position based, at least in part, on the first sensor data
Implementation Method 2
measuring, at a first position of the mobile device, a first radio signal characteristic; measuring, at a second position of the mobile device, a second radio signal characteristic
Data Source
AI summary
Method, mobile device, computer program product, and apparatus for optimizing sensor reporting are described. A mobile device can measure radio frequency (RF) signal characteristics while receiving data from one or more mobile device sensors. The mobile device may determine its relative displacement between RF signal measurements. The mobile device can send a representation of the RF signal characteristics and the displacement data to one or more servers. The representation displacement data may include one or more reliability characteristics and/or a displacement reliability rating. A server can obtain the displacement data and RF signal characteristics to determine positioning of wireless transmitters in an environment and build a positioning database.