WiFi Tomographic Mapping for Through-Wall Detection
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Solution Overview
Problem
Existing methods for mapping the interior of a building and detecting movement within it are imprecise and not economically viable for widespread adoption by first responders, such as military personnel and law enforcement, as they fail to provide detailed information about the structure's contents and occupants before entry.
Innovation Solution
The use of commercial off-the-shelf WiFi transceivers and tomographic backprojection processing to create a crude map of a building's interior by analyzing signal strength and attenuation patterns, combined with the detection of electromagnetic field disturbances to identify obstacles and movement, utilizing a network of transceivers positioned both inside and outside the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional radar devices like RadarScope are used to detect movement through walls, then movement detection capability is provided, but location precision and detailed interior mapping are insufficient
Solution Approach 1:
The system divides the detection task into multiple segments by deploying multiple WiFi transceivers at different locations around the structure. Each transceiver captures signal data from a specific viewpoint, and the combination of multiple segmented measurements enables precise location determination through tomographic reconstruction algorithms.
Solution Approach 2:
The system transitions from traditional 2D radar scanning to 3D spatial mapping by collecting WiFi signal data from multiple transceiver locations around the structure. This multi-dimensional data collection approach enables reconstruction of interior layouts and object positions in three-dimensional space, significantly improving location precision.
2Measurement precision
If specialized mapping equipment is deployed to achieve accurate interior mapping, then mapping precision improves, but cost and ease of deployment deteriorate
Solution Approach 1:
The system replaces expensive specialized mapping equipment with inexpensive commercial WiFi transceivers that are already widely deployed. These low-cost devices can be quickly positioned around structures without requiring complex installation, making the system economically viable for widespread adoption by first responders.
Solution Approach 2:
The system leverages the universality of WiFi technology, which is already present in most modern devices. By repurposing existing WiFi transceivers for mapping and detection purposes, the system eliminates the need for specialized equipment while maintaining mapping accuracy, thereby reducing deployment costs.
3Measurement precision
If more transceivers are deployed to improve mapping accuracy and coverage, then measurement precision improves, but device complexity and deployment difficulty increase
Solution Approach 1:
The system employs self-organizing algorithms that automatically process data from multiple transceivers and reconstruct interior maps without requiring manual configuration or complex coordination during deployment. The transceivers independently collect data and the central processing system automatically integrates the information, simplifying the deployment process.
Solution Approach 2:
The system uses pre-programmed algorithms and automated data processing routines that are prepared in advance. When transceivers are deployed, the algorithms automatically take over to coordinate data collection and perform tomographic reconstruction, eliminating the need for operators to manually manage the complexity of multiple devices.
4Loss of information
If existing radar systems are used for first responder applications, then basic movement detection is achieved, but actionable intelligence about interior layout and occupant position is insufficient
Solution Approach 1:
The system merges multiple data sources including WiFi signal strength measurements, phase information, and data from multiple transceiver locations into a unified interior map. This integration of multiple information streams provides comprehensive intelligence about both the physical layout and occupant positions, far exceeding what single-source radar systems can provide.
Solution Approach 2:
The system replaces traditional mechanical radar scanning systems with electromagnetic field-based WiFi signal analysis. By using WiFi signals and tomographic reconstruction algorithms instead of mechanical radar, the system achieves superior information completeness about interior structures while maintaining manageable system complexity through software-based processing.
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
This approach enables the production of accurate, economical, and rapidly deployable see-through-the-walls capability, providing first responders with critical information about the building's layout and occupant movement, enhancing safety and mission success.
Implementation Method 1
transceivers positioned to transmit and receive signals that pass through at least a portion of a structure of interest... using the strength of the received signals and the locations of the transceivers to infer the presence of a person or other object
Implementation Method 2
interior maps of a building may be produced using a set of WiFi transmitters and receivers and a processing method such as tomographic backprojection
Data Source
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AI summary
An apparatus includes a plurality of transceivers positioned to transmit and/or receive signals that pass through at least a portion of a structure of interest, wherein each of the transceivers receives a signal from at least one of the other transceivers, and a processor using the strength of the received signals, the locations of the transceivers, prior knowledge of building practices, and exterior characteristics of the structure to produce a map of the structure of interest and/or to detect movement of persons in the structure of interest. A method of producing a map of the structure of interest and/or detecting the movement of persons in the structure of interest is also provided.