Wireless Motion Detection via Multipath Channel Analysis
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Solution Overview
Problem
Existing object motion detection systems, such as those using passive infrared (PIR) and ultrasonic sensors, face challenges with accuracy, false alarms, limited range, and the need for line-of-sight, making them unsuitable for reliable motion detection in rich-scattering environments like indoor or urban areas.
Innovation Solution
A wireless monitoring system utilizing asynchronous heterogeneous Type 1 and Type 2 devices that transmit and receive wireless signals through a wireless multipath channel impacted by object motion, obtaining time series of channel information to detect motion accurately without line-of-sight requirements, offering a larger detection range and lower false alarm rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive infrared (PIR) sensors are used for motion detection, then the system can detect motion, but it produces false alarms due to sensitivity to environmental changes and requires line-of-sight
Solution Approach 1:
The patent replaces optical and acoustic sensing mechanisms with wireless communication-based detection. Instead of using PIR sensors that detect thermal radiation or ultrasonic sensors that detect sound waves, the system uses wireless signals (e.g., WiFi, Bluetooth) to detect motion by analyzing changes in the wireless channel characteristics such as signal strength, phase, and multipath components. This substitution eliminates the harmful sensitivity to environmental factors like temperature changes and sunlight that cause false alarms in traditional PIR systems.
Solution Approach 2:
The patent introduces wireless signals as an intermediary medium between the transmitter and receiver. Rather than directly detecting motion through optical or acoustic means, the system uses wireless signals that interact with the environment (walls, furniture, obstacles) to create a rich scattering pattern. Motion detection is achieved by analyzing changes in these wireless signal interactions, providing a more reliable detection mechanism that is not directly affected by environmental factors like temperature or sunlight.
2Reliability
If ultrasonic sensors are used for motion detection, then the system can detect motion, but it cannot penetrate solid objects and causes gaps in detection field
Solution Approach 1:
The patent replaces ultrasonic acoustic waves with electromagnetic wireless signals. Electromagnetic signals can penetrate solid objects like walls and furniture, unlike ultrasonic waves that require air transmission and cannot pass through solids. This substitution allows the detection system to achieve complete coverage throughout the monitoring area without gaps, as wireless signals can propagate through and around obstacles to provide continuous detection capability.
Solution Approach 2:
The patent changes the fundamental propagation parameter from acoustic wave frequency (ultrasonic) to electromagnetic wave frequency (radio frequency). This parameter change enables the detection system to penetrate solid objects and achieve omnidirectional coverage. The system analyzes changes in wireless signal parameters (amplitude, phase, multipath components) caused by motion, providing reliable detection throughout the entire monitoring area without the gaps inherent in ultrasonic systems.
3Reliability
If PIR sensors are used for motion detection, then the system can detect motion, but it has limited range and requires multiple devices
Solution Approach 1:
The patent makes wireless signals serve multiple functions simultaneously. The same wireless communication infrastructure (routers, access points, smartphones) used for data communication also serves as the detection medium for motion sensing. This multi-functionality eliminates the need for separate dedicated detection devices and extends the detection range to cover the entire area where wireless signals are transmitted, as the existing wireless network infrastructure provides both communication and detection capabilities.
Solution Approach 2:
The patent substitutes the limited-range optical/thermal detection mechanism with electromagnetic wireless signal propagation. Wireless signals naturally propagate over longer distances and can be transmitted through multiple devices (routers, access points, smartphones) throughout the monitoring area. This substitution provides extensive detection coverage without requiring multiple dedicated devices, as the wireless signals already present in the environment can be utilized for detection purposes.
4Reliability
If traditional motion sensors are used, then the system can detect motion, but it is easily defeated by blocking the body heat emission or wearing special suits
Solution Approach 1:
The patent replaces thermal radiation detection (PIR) and acoustic detection (ultrasonic) with electromagnetic wireless signal detection. Since the detection is based on analyzing changes in wireless signal characteristics (amplitude, phase, multipath components) rather than detecting body heat or sound, it becomes impossible to defeat the system by wearing heat-insulating suits or anechoic suits. The wireless signals interact with the environment and the moving object in a way that cannot be blocked by conventional protective clothing.
Solution Approach 2:
The patent uses wireless signals as an intermediary that interacts with the environment and moving objects in a way that is not easily blockable. The wireless signals create a rich scattering pattern by interacting with walls, furniture, and obstacles, and motion is detected by analyzing changes in these interactions. This intermediary approach makes the detection system immune to blocking by body heat emission or special suits, as the wireless signals are already penetrating and interacting with the environment before reaching the moving object.
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
The system provides high detection accuracy and low false alarm rates, capable of detecting motion behind obstacles and around corners, with a larger detection range and reduced sensitivity to environmental changes, making it suitable for diverse environments.
Implementation Method 1
transmitting a wireless signal through a wireless multipath channel impacted by a motion of an object
Data Source
AI summary
Methods, apparatus and systems for object motion detection are disclosed. In one example, a system having at least a processor and a memory with a set of instructions stored therein for detecting object motion in a venue is disclosed. The system comprises: a first wireless device configured for transmitting a wireless signal through a wireless multipath channel impacted by a motion of an object in the venue; and a second wireless device that has a different type from that of the first wireless device and is configured for: receiving the wireless signal through the wireless multipath channel impacted by the motion of the object in the venue, and obtaining a time series of channel information (CI) of the wireless multipath channel based on the wireless signal; and a motion detector configured for detecting the motion of the object in the venue based on motion information related to the motion of the object, wherein the motion information associated with the first and second wireless devices is computed based on the time series of CI by at least one of: the motion detector and the second wireless device.