WLAN Sensing Access Point Multi-Link Motion Detection
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Solution Overview
Problem
Existing WLAN sensing techniques face challenges in accurately detecting motion and determining proximity due to the difficulty in reliably monitoring changes in single radio links, which can lead to inconsistent motion detection and proximity assessment.
Innovation Solution
Implementing a system that tracks changes in channel estimates across multiple WLAN links, using signal processing algorithms to detect variance in phase or eigenvalues of channel estimates, and combining results using logical operations or majority decision logic to indicate proximity detection, with consideration of SNR and RSSI for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single radio link is monitored for motion detection, then device complexity is reduced, but measurement precision and reliability of motion detection deteriorate
Solution Approach 1:
The patent combines multiple radio links (first link between first AP and first STA, second link between second AP and second STA) into a unified sensing system. By merging measurements from multiple independent links, the system achieves more reliable motion detection through aggregation of channel estimate variations across all links, resolving the contradiction between system simplicity and detection accuracy.
Solution Approach 2:
The patent transitions from monitoring a single radio link to monitoring multiple radio links simultaneously, adding a dimensional aspect to the measurement space. This multi-link dimensionality enables the system to distinguish true motion from false alarms by analyzing patterns across multiple dimensions of channel data.
2Reliability
If multiple radio links are monitored for motion detection, then measurement precision and reliability of motion detection are improved, but device complexity increases
Solution Approach 1:
The patent segments the sensing system into independent radio link monitors, where each link (first link with first AP/first STA, second link with second AP/second STA) is processed separately through its own channel estimation and variance calculation. This segmentation allows complex multi-link monitoring to be broken down into manageable modular units, reducing overall system complexity while maintaining high reliability through multi-link aggregation.
3Measurement precision
If channel estimate variations are analyzed for motion detection, then measurement precision is improved, but difficulty of detecting and measuring increases
Solution Approach 1:
The patent employs self-service processing where the system uses its own transmitted reference signals (beacon frames or probe request/response frames) to generate channel estimates. The channel variance calculation is performed autonomously using the transmitted and received signal characteristics, eliminating the need for external measurement equipment or complex external signal processing, thereby reducing the difficulty of detection while maintaining precision.
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
Enhances the reliability of motion detection and proximity assessment by using multiple WLAN links to consistently identify motion proximity to a device, improving detection accuracy and reducing false alarms through optimized threshold settings and signal processing operations.
Implementation Method 1
WLAN sensing enables motion detection, gesture recognition as well as biometric measurement by using WLAN signals
Implementation Method 2
tracking changes in channel estimates of each of a plurality of radio links
Implementation Method 3
detecting motion in a given environment can be performed measuring changes in the channel estimates of the WLAN link over time
Implementation Method 4
as a person or object moves around a given environment, it impacts how a WLAN signal propagates from transmitter to receiver (e.g., propagation paths are created and destructed generating time-varying multipath fading)
Data Source
AI summary
Embodiments of a STA configured for proximity detection by multiple WLAN link tracking are disclosed herein. In some embodiments, the STA performs WLAN sensing using two or more WLAN links with one or more other STAs to track a channel state of each link and performs motion detection based on the tracked channel state of each WLAN link to detect motion in any of the WLAN links. If motion is detected in at least some of the WLAN links, the STA may perform proximity detection to indicate proximity by combining results of the WLAN sensing for each link to determine whether the motion is proximate to the STA or proximate to one of the other STAs.