Passive Target Tracking via WiFi Doppler Shift
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for tracking a target require the target to transmit signals or use active querying, which can be invasive and require precise synchronization and infrastructure.
Innovation Solution
The method utilizes Doppler shift measurements from existing radio signals, such as WiFi, to track a target without requiring the target to transmit signals or use active querying, employing techniques like extended Kalman filter, Viterbi algorithm, and particle filter for position estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods use active querying or target signal transmission for tracking, then tracking accuracy is improved, but the target becomes aware of being tracked and infrastructure requirements increase
Solution Approach 1:
The system uses existing radio signals in the environment that the target is already exposed to, rather than requiring the target to transmit signals or be actively queried. The Doppler shift of these ambient signals reflects the target's motion, enabling passive tracking without the target knowing it is being tracked.
Solution Approach 2:
The patent uses existing radio signals in the environment as an intermediary to carry information about the target's motion. These signals reflect off the target and return with Doppler shift, allowing tracking without direct communication between the tracking system and target.
2Loss of information
If active querying methods are used for target tracking, then position information can be obtained, but precise synchronization and infrastructure are required
Solution Approach 1:
The system leverages existing radio signals already present in the environment, eliminating the need for specialized infrastructure or synchronized communication systems. The ambient signals serve the dual purpose of their original function and as carriers for tracking information.
Solution Approach 2:
The patent makes existing radio signals serve multiple functions: their original communication purpose and as carriers for tracking information. This eliminates the need for dedicated tracking infrastructure and reduces system complexity.
3Object-affected harmful factors
If passive tracking using existing signals is used, then covert tracking is achieved, but measurement precision may be reduced
Solution Approach 1:
The patent applies advanced signal processing techniques including extended Kalman filters, Viterbi algorithms, and particle filters to extract precise position information from the Doppler shift measurements. These algorithms compensate for the challenges of passive tracking and maintain high measurement 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
This approach allows for covert tracking without indicating to the target that it is being tracked, does not require close synchronization of receivers, and can utilize existing signals, making it versatile for various settings.
Implementation Method 1
tracks the target position from channel state information Doppler frequency measurements
Data Source
AI summary
For tracking a target, method detects, by use of a processor, that the target is present. The method estimates an initial target position. The method further tracks the target position from channel state information Doppler frequency measurements using at least one of an extended Kalman filter, a Viterbi algorithm, and a particle filter.