Mobile Device Location Calculation Using Memory-Efficient Signal Filtering
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Solution Overview
Problem
Existing RFID tracking systems in retail environments face challenges with data overload, as they generate large amounts of signal strength data that overwhelm random access memory, leading to inefficient device location calculations and inaccurate positioning due to incorrect assumptions about signal strength and distance correlations.
Innovation Solution
The system reduces computational load by storing only signal strengths above a threshold, interpolating missing data, and averaging access point locations to determine device positions, while also limiting the number of tracked devices and using memory cleanup processes to manage data storage effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all signal strength data from multiple access points is stored in random access memory for location calculation, then location accuracy can be maintained, but memory capacity is overwhelmed and system efficiency deteriorates
Solution Approach 1:
The patent extracts and stores only the essential location information (access point identifiers and their spatial coordinates) in a lookup table, while temporarily holding minimal measurement data in random access memory during processing. This separates the permanent reference data from the transient measurement data, preventing memory overflow while preserving location calculation accuracy.
Solution Approach 2:
The system pre-calculates and stores the spatial coordinates of all access points in a lookup table before location determination begins. This preliminary action eliminates the need to store and process raw signal strength data from multiple access points during runtime, reducing memory requirements while maintaining accurate location computation.
2Measurement precision
If signal strength data from all access points is processed for location determination, then positioning accuracy is improved, but processing time increases
Solution Approach 1:
The patent extracts only the necessary access point identifiers from the signal strength data and retrieves their pre-stored spatial coordinates from the lookup table, avoiding unnecessary processing of redundant signal strength information. This extraction approach maintains positioning accuracy while significantly reducing computation time.
Solution Approach 2:
Instead of processing raw signal strength data from multiple access points, the system copies the pre-stored spatial coordinates of relevant access points from the lookup table to determine device location. This copying operation is much faster than performing complex signal strength analysis while preserving the essential location information.
3Reliability
If complete measurement data is retained for correlation analysis, then tracking accuracy is improved, but memory consumption increases
Solution Approach 1:
The patent extracts only the critical correlation elements (device identifiers and access point identifiers) from complete measurement data for storage and comparison. By extracting and storing only these essential identification elements rather than complete signal strength measurements, the system maintains tracking accuracy while minimizing memory consumption during data retention periods.
Data Source
AI summary
For a measurement period, signal strengths, device identifiers and access point identifiers are received from a plurality of access points. A record for the measurement period is stored in random access memory with the record being associated with a single device identifier and containing access point identifiers associated with signal strengths received for the measurement period. The location of a device is determined for the measurement period by retrieving spatial coordinates of a corresponding access point for each access point identifier in the record for the measurement period and setting the location of the device for the measurement period to the average of the retrieved spatial coordinates.