Passive Multi-Person Location Tracking Using Signal Polarization
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Solution Overview
Problem
Existing tracking technologies, such as Wi-Fi-based systems, are unable to effectively track multiple individuals moving simultaneously within a tracking environment due to the complexity of signal reflection paths changing with multiple individuals, which current methods are not designed to handle.
Innovation Solution
A passive multi-person location tracking system utilizing signal polarization, specifically employing polarimetry with Wi-Fi devices to differentiate and locate individuals by analyzing the polarization axial ratio angle and other location parameters from reflected signals, allowing for the use of commercial off-the-shelf equipment in various environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Wi-Fi-based tracking technology is used, then passive tracking of individuals is enabled, but tracking becomes impossible when multiple individuals move simultaneously within the environment
Solution Approach 1:
The patent applies parameter changes by utilizing polarization parameters (polarization axial ratio angle) in addition to traditional location parameters (time of flight, angle of arrival). This additional parameter dimension enables the system to differentiate between multiple reflection paths caused by multiple individuals, resolving the contradiction between maintaining tracking reliability and adapting to multi-person environments.
2Reliability
If radar technology is used for tracking, then tracking and ranging operations can be performed, but special technology and equipment are required that are impractical in many environments
Solution Approach 1:
The patent employs copying by using commercial off-the-shelf Wi-Fi devices to replicate radar-like tracking functionality. Instead of implementing specialized radar hardware, the system copies the tracking function using widely available Wi-Fi equipment, thereby maintaining reliability while dramatically improving ease of manufacture and deployment practicality.
3Ease of manufacture
If existing Wi-Fi tracking technology is used, then simple equipment can be deployed, but the technology cannot provide tracking when multiple individuals move simultaneously
Solution Approach 1:
The patent applies dimensionality change by introducing polarization parameters as an additional dimension for signal analysis. While existing Wi-Fi tracking only analyzes traditional parameters (time, angle), this invention adds the polarization dimension, enabling the system to distinguish between multiple individuals using the same Wi-Fi equipment, thereby improving multi-person tracking capability without sacrificing equipment simplicity.
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
Enables accurate and stable location tracking of multiple persons by processing channel state information from multiple receivers, overcoming the limitations of existing technologies and providing reliable tracking in dynamic environments.
Implementation Method 1
receiving reflected signals from the tracking environment at a first receiver at a first location and a second receiver at a second location
Implementation Method 2
transmitting polarized radio signals from a Wi-Fi transmitter at a first location, the polarized signals including a first signal transmitted with a horizontal polarization and a second signal transmitted with vertical polarization
Data Source
AI summary
Embodiments are directed to passive multi-person location tracking utilizing signal polarization. An embodiment of a system includes multiple receivers, including a first receiver at a first location and a second receiver at a second location, each receiver including one or more receiver antennas to receive polarized radio signals; a transmitter located at a third location to transmit polarized radio signals, the transmitter including antennas for a first signal at a first polarization direction and a second signal at a second, different polarization direction; and a processing system to receive channel state information from each receiver, and to track a plurality of individuals utilizing the received channel state information, wherein the tracking of the plurality of individuals is based at least in part on analysis of a polarization parameter and a set of location parameters generated for each of multiple reflection paths based on the channel state information.