Wireless Zone Tracking Using RSSI and Entry-Exit Thresholds
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Solution Overview
Problem
Existing location determination methods using wireless signals are prone to reliability issues due to signal interference and lack of knowledge about physical structures, making it difficult to accurately determine if a device is in a particular zone and count the number of devices within a zone.
Innovation Solution
A location/zone tracking server that utilizes RSSI information, combined with knowledge of physical structures like doorway locations, to reliably determine device presence and count within zones by applying different threshold criteria for initial entry and continued presence, and considers passageways to reduce false determinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RSSI-based location determination is used, then location estimation can be obtained, but reliability is poor due to signal interference and lack of physical structure knowledge
Solution Approach 1:
The patent introduces an intermediary approach by combining RSSI measurements with knowledge of physical structures (doorways, hallways, floors) to mediate between signal-based location estimation and actual physical zone determination. This intermediary layer of physical structure knowledge filters out false location determinations caused by signal interference.
Solution Approach 2:
The patent replaces pure signal-strength-based location determination with a hybrid system that incorporates spatial reasoning about physical structures. Instead of relying solely on the mechanical/electromagnetic RSSI measurements, the system uses logical deductions about how devices move through physical spaces (doorways, hallways) to verify zone presence.
2Productivity
If signal strength measurements are used for zone presence determination, then device presence can be detected, but false determinations occur due to signal jitter and interference
Solution Approach 1:
The patent implements feedback mechanisms where the system continuously monitors both RSSI measurements and device location history, using this feedback to adjust zone presence determinations. When signal jitter causes temporary false determinations, the feedback loop detects these anomalies and corrects them by comparing against physical structure knowledge and historical movement patterns.
Solution Approach 2:
The patent performs preliminary actions by pre-establishing knowledge of physical structures (doorway locations, hallway configurations, floor layouts) before actual zone presence determination occurs. This preliminary structural knowledge serves as a reference framework that prevents false determinations during real-time device tracking.
3Ease of operation
If simple RSSI threshold criteria are applied, then zone presence can be determined quickly, but accuracy is reduced due to inability to distinguish between true presence and false determinations
Solution Approach 1:
The patent segments the zone presence determination process into multiple independent components: RSSI measurement, physical structure knowledge, device location history, and threshold criteria. Each component handles a specific aspect of the problem, and their modular combination allows the system to maintain simplicity in individual components while achieving high accuracy through their integrated operation.
Data Source
AI summary
Methods and apparatus relating to the detection of one or more devices in zones, e.g., non-overlapping areas, are described. Individual device locations are made based on RSSI information. Whether a user is determined to be in a zone or not is determined based on location determinations corresponding to the device. Thresholds used to determine whether a device is to be considered as being within a zone differs depending on whether the device is newly detected in the zone or is already determined to be in the zone. In some embodiments it is easier to be determined to be in a zone than to be determined to have left a zone. A device may be determined to be in two non-overlapping zones at the same time thereby increasing the chance that devices in edge areas will be counted with regard to the number of devices for which resources should be provided.