Beacon Clusters with Offset Stations for Location Accuracy
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Solution Overview
Problem
BLE location-determining systems face accuracy issues due to RSSI fluctuation caused by co-channel interference and multipath fading, and the presence of jittering areas where mobile devices cannot determine proximity to adjacent beacon stations, complicating location determination and requiring complex system modifications.
Innovation Solution
The system employs beacon-broadcasting clusters with primary and offset-assisted stations, where offset-assisted stations are positioned to form an evenly-spaced sequence with the primary station, and each station broadcasts distinguishable component beacons for diversity reception, reducing jittering areas and RSSI fluctuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple beacon stations are deployed to improve location determination accuracy, then coverage area increases, but jittering areas between adjacent stations increase causing uncertainty in proximity determination
Solution Approach 1:
The patent divides the coverage area into multiple zones based on RSSI thresholds, creating distinct proximity regions (immediate, near, far, unknown) around each beacon station. This segmentation allows clear differentiation between adjacent stations' coverage areas, eliminating jittering zones where devices cannot determine proximity. Each zone is defined by specific RSSI ranges, providing unambiguous location determination throughout the entire coverage area.
2Ease of manufacture
If RSSI measurement is used for proximity determination, then implementation is simple, but RSSI fluctuation due to co-channel interference and multipath fading reduces determination accuracy
Solution Approach 1:
The patent changes the parameter used for proximity determination from raw RSSI values to normalized RSSI ratios. By calculating the ratio of RSSI from the target station to RSSI from reference stations, and normalizing this ratio against pre-stored reference values, the system compensates for RSSI fluctuations caused by co-channel interference and multipath fading. This parameter transformation maintains measurement precision while preserving implementation simplicity.
3Measurement precision
If beacon stations are placed at known locations to enable location determination, then location estimation becomes possible, but co-channel interference from other wireless systems introduces RSSI fluctuation
Solution Approach 1:
The patent introduces reference stations as intermediary elements to eliminate the harmful effect of co-channel interference. By measuring RSSI from multiple reference stations and using these measurements to normalize the target station's RSSI, the system creates a relative measurement framework that cancels out common interference factors. The reference stations act as mediators that transform absolute RSSI measurements (vulnerable to interference) into relative ratios (resistant to interference).
Data Source
AI summary
A system comprising beacon-generating clusters for enabling a mobile computing device to perform location or proximity determination is provided. Each cluster comprises a primary station for broadcasting a primary beacon, and an offset-assisted station, positioned from the primary station by an offset distance along a direction, for broadcasting a secondary beacon. The offset distance and the direction are unique for all the clusters, causing a jittering area, within which the mobile computing device is unable to determine which one of adjacent primary stations is closer to from detecting the primary beacons, to be reduced by further utilizing the secondary beacons provided by the clusters. Fluctuation in received signal strength indicator (RSSI) can be reduced by having each station, primary or secondary, installed with multiple co-located broadcasting units for utilizing space and time diversity to reduce RSSI fluctuation. In another option, multiple offset-assisted stations are used for each cluster.