Wifi Frequency Subset Scanning for Location Estimation
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Solution Overview
Problem
Existing location estimation methods for wireless devices, such as cell phones and laptops, face challenges in indoor settings where GPS signals are weak, and the process of discovering nearby Wifi access points is power-intensive, leading to battery drain.
Innovation Solution
A method where a wireless computing device scans a subset of frequencies associated with strong and fixed Wifi base stations, reducing power consumption while maintaining accurate location estimation by using a subset of base stations that are within a threshold distance of each other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a device scans all Wifi frequencies to discover access points for location estimation, then location accuracy is improved, but power consumption increases
Solution Approach 1:
The patent divides the frequency spectrum into multiple frequency sets and further segments them into frequency subsets. Instead of scanning all frequencies at once, the device scans only selected subsets, reducing power consumption while maintaining location estimation accuracy through incremental updates.
Solution Approach 2:
The patent performs partial frequency scanning by selecting only certain frequency subsets rather than scanning the entire frequency spectrum. This partial action is sufficient to discover enough access points for accurate location estimation without the excessive power consumption of a full scan.
2Measurement precision
If a device performs frequent full frequency scans to maintain accurate location tracking, then location update accuracy is improved, but battery life deteriorates
Solution Approach 1:
The patent implements periodic location estimation using incremental updates based on previously scanned frequency subsets. Instead of performing continuous full scans, the device periodically updates location using selected frequency subsets, maintaining accuracy while extending battery life through reduced scanning frequency and scope.
Solution Approach 2:
The patent performs preliminary frequency scans to discover access points and build a location database in advance. This preliminary action allows subsequent location updates to be performed more efficiently using stored information and selective re-scanning of only necessary frequency subsets.
3Measurement precision
If a device uses GPS for location estimation, then outdoor location accuracy is improved, but indoor location capability deteriorates
Solution Approach 1:
The patent creates a universal location estimation system that works both outdoors and indoors by using Wifi access point discovery and frequency subset scanning. This multi-functional approach replaces GPS-dependent outdoor positioning with a hybrid system that maintains accuracy in both environments, particularly excelling indoors where GPS signals are unavailable.
Data Source
AI summary
A wireless computing device may scan a frequency set. A first group of base stations may use the frequencies in the frequency set. Based on information relating to one or more base stations in the first group of base stations, the wireless computing device may estimate its location. The wireless computing device may further select a frequency subset of the frequency set. A second group of base stations may use the frequencies of the frequency subset. Based on information relating to one or more base stations in the second group of base stations, the wireless computing device may again estimate its location. If the two estimated locations are within a threshold distance of one another, the wireless computing device may perform, during a subsequent location-estimating operation, an additional frequency scan using the frequency subset.