Passive Motion Detection via Wireless PHY Frame Analysis
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Solution Overview
Problem
Current motion detection systems rely on infrared or optical sensors, which may not provide discreet or efficient motion sensing, especially in environments where direct observation is not feasible, and they often require association with the wireless network they are monitoring.
Innovation Solution
A wireless sensor device that passively detects motion by eavesdropping on over-the-air signals exchanged between network devices, using beamforming dynamic information and channel state data from IEEE 802.11 standards to infer motion without being part of the network, allowing for discreet and geographically flexible motion detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If infrared or optical sensors are used for motion detection, then motion detection capability is provided, but the system requires direct observation and association with the wireless network being monitored
Solution Approach 1:
The patent replaces traditional mechanical/optical sensing systems with a wireless signal-based detection system. By using wireless communication signals (beamforming reports and PHY frames) as the sensing medium, the system eliminates the need for direct line-of-sight observation and complex network association, allowing passive motion detection through signal analysis alone
Solution Approach 2:
The system performs dual functionality by simultaneously serving as a wireless communication receiver and a motion detection sensor. The same wireless signal reception infrastructure is used both for communication and for extracting motion information, eliminating the need for separate dedicated sensing hardware and network association protocols
2Object-generated harmful factors
If passive eavesdropping on over-the-air signals is used, then discreet motion detection is achieved, but measurement precision may be compromised
Solution Approach 1:
The patent merges multiple sources of information from wireless signals (beamforming reports containing channel state information and PHY frames containing training fields) to compensate for the passive nature of eavesdropping. By combining data from these different signal components, the system achieves accurate motion detection while maintaining operational discretion
Solution Approach 2:
The wireless signals themselves serve as intermediaries that carry both communication data and motion information. By analyzing changes in these intermediary signals (particularly beamforming dynamic information), the system can infer motion without direct observation, maintaining discreteness while achieving sufficient measurement precision
3Measurement precision
If beamforming dynamic information is analyzed, then motion detection accuracy is improved, but processing complexity increases
Solution Approach 1:
The patent extracts only the essential motion-related features from the complex beamforming dynamic information, rather than processing the entire signal set. By focusing on specific parameters that directly correlate with motion (such as changes in channel state information), the system achieves high detection accuracy while reducing processing complexity
Solution Approach 2:
The system performs preliminary processing of wireless signals by extracting and storing beamforming dynamic information and PHY frame data before motion analysis. This preliminary organization of data structures the information in advance, making subsequent motion detection processing more efficient and less complex
Data Source
AI summary
In a general aspect, motion is detected in an environment using wireless signals. In one example, a downlink high-efficiency PHY (HE-PHY) frame is received. The downlink HE-PHY frame is transmitted by an access point device to wireless communication devices residing inside an environment. An uplink orthogonal frequency-division multiple access (UL-OFDMA) transmission is subsequently received in response to the downlink HE-PHY frame. The UL-OFDMA transmission is transmitted by the wireless communication devices to the access point device. The UL-OFDMA transmission includes uplink HE-PHY frames simultaneously transmitted on respective resource units by the respective wireless communication devices. A motion data set is generated based on channel responses computed from the uplink HE-PHY frames. Each channel response is computed from a respective one of the uplink HE-PHY frames. Motion within the environment is analyzed based on the motion data set.