Indoor Location Accuracy via Signal Histogram Interpolation
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Solution Overview
Problem
Existing methods for determining the indoor location of mobile devices using wireless signal strength are inaccurate due to unreliable RSSI values caused by power-saving patterns in smartphones and tablets, which are not effectively addressed by current technologies.
Innovation Solution
A method that corrects signal power values by interpolating zero count values in histograms of signal power measurements, using a radio map to assign probabilities to locations based on signal power vectors, and determining device location by the highest probability, applicable to consumer-grade devices without requiring extensive training or additional infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If RSSI values are used directly for indoor location determination, then the method is simple to implement, but the location accuracy deteriorates due to power-saving patterns causing unreliable measurements
Solution Approach 1:
The patent applies preliminary action by performing interpolation to correct zero count values in the histogram before using the signal power measurements for location determination. This pre-processing step fills in missing measurement data that would otherwise cause inaccurate location results, thereby resolving the contradiction between simple implementation and accurate measurement.
2Measurement precision
If dedicated location determination infrastructure is deployed, then location accuracy is improved, but system complexity and cost increase
Solution Approach 1:
The patent applies self-service by enabling standard mobile devices to perform their own location determination using existing WLAN infrastructure and signal measurements. The devices autonomously correct their own measurement errors through histogram interpolation without requiring external correction infrastructure, thus achieving accurate location determination without increasing system complexity.
Solution Approach 2:
The patent applies universality by using existing WLAN access points for both their primary data communication function and as signal emitters for location determination. This multi-functional use of existing infrastructure eliminates the need for dedicated location determination equipment, thereby maintaining system simplicity while achieving accurate indoor location.
3Reliability
If multiple signal measurements are collected to improve reliability, then measurement reliability is improved, but power consumption increases due to continuous monitoring
Solution Approach 1:
The patent applies periodic action by collecting signal power measurements at discrete intervals and organizing them into histograms with binning. This periodic measurement approach provides sufficient statistical reliability for location determination without requiring continuous monitoring, thereby reducing power consumption while maintaining measurement reliability.
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 method achieves accurate indoor location determination with precision up to 1 meter, enabling effective deployment in indoor location-based services without expanding existing infrastructure, and corrects for power-saving induced noise in RSSI values.
Implementation Method 1
a mobile computing device capable of receiving electromagnetic signals from a set of K>1 access points emitting such signals, and measuring the signal power thereof
Implementation Method 2
correcting zero count values in histograms of signal power measurements, using a radio map to assign probabilities to locations
Data Source
AI summary
The present invention relates to a method of determining the indoor position of a mobile computing device using the signal strength measurements of a plurality of electromagnetic signals which are emitted from fixed locations. By using a heuristic which takes the observed behavior of signal strength measuring devices into account, the method allows to increase the accuracy and robustness of similar known methods.