Wireless Object Tracking via Channel Impulse Response Segmentation
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Solution Overview
Problem
Existing indoor localization systems fail to effectively track multiple persons in rich-scattering environments due to superimposed signals from targets and other objects, requiring cumbersome calibration and specialized hardware, with limited ability to disentangle weak signals.
Innovation Solution
A wireless tracking system using a single 802.11ad device with digital beamforming and a multi-object detection algorithm, along with robust clustering techniques, to achieve high spatial resolution and track multiple users, demonstrated to achieve a median location error of 9.9 cm for dynamic targets and 19.7 cm for static targets with a people counting error ≤1 for 97.8% of the time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single wireless device is used for tracking, then device complexity is reduced, but measurement precision deteriorates due to signal superposition
Solution Approach 1:
The patent segments the wireless channel response into multiple path components using Channel Impulse Response (CIR) analysis. By decomposing the superimposed signal into distinct propagation paths (direct path, reflected paths), the system can identify and separate signals from different targets, enabling multi-person localization with a single device despite signal superposition.
Solution Approach 2:
The patent introduces Channel State Information (CSI) as an intermediary that captures detailed characteristics of the wireless channel. By analyzing CSI parameters including phase, amplitude, and temporal variations, the system extracts target information without requiring multiple physical devices, thus maintaining low device complexity while achieving accurate measurement.
2Measurement precision
If dense device deployment is used, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent enables a single wireless device to perform self-calibration and self-tracking by analyzing temporal variations in channel responses. The system uses reference signals and correlation analysis to automatically identify target positions and trajectories without requiring external calibration equipment or multiple synchronized devices, eliminating the need for dense deployment.
Solution Approach 2:
The patent exploits temporal changes in channel parameters (phase, amplitude, delay) to distinguish between static and moving targets. By monitoring how channel responses evolve over time and comparing them against reference measurements, the system achieves high measurement precision with a single device, avoiding the complexity of deploying multiple devices.
3Measurement precision
If specialized hardware with multiple antennas is used, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent makes standard wireless communication hardware universal for both communication and sensing functions. By utilizing the existing antenna array and signal processing capabilities of conventional wireless devices, the system achieves high spatial resolution for multi-target tracking without requiring specialized hardware with multiple dedicated antennas, thus reducing device complexity.
Solution Approach 2:
The patent replaces mechanical beamforming and physical antenna arrays with digital signal processing techniques. Instead of using multiple physical antennas for spatial resolution, the system employs digital beamforming and correlation analysis on channel impulse responses, achieving equivalent or superior spatial resolution with simpler hardware requirements.
4Measurement precision
If calibration is performed for each target, then measurement precision improves, but loss of time increases
Solution Approach 1:
The patent performs preliminary calibration by establishing a reference channel response before tracking begins. By measuring the channel response without targets present and storing it as a reference, the system enables rapid tracking of multiple targets without requiring individual calibration for each target, thus reducing time loss while maintaining precision.
Solution Approach 2:
The patent implements continuous tracking by monitoring temporal variations in channel responses without interrupting for recalibration. The system continuously compares current channel measurements against the reference and updates target positions in real-time, maintaining measurement precision while eliminating the time loss associated with per-target calibration procedures.
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 enables accurate multi-person localization and tracking without the need for dense device deployment or prior training, achieving high accuracy in both dynamic and static target localization with low error rates.
Implementation Method 1
receiving a second wireless signal using a plurality of receive antennas through the wireless multipath channel between the transmitter and the receiver
Implementation Method 2
The second wireless signal differs from the first wireless signal due to the wireless multipath channel and a modulation of the first wireless signal by the at least one object
Data Source
AI summary
Methods, apparatus and systems for wireless object tracking are described. In one example, a described wireless tracking system comprises: a transmitter, a receiver, and a processor. The transmitter is configured for transmitting a first wireless signal using a plurality of transmit antennas towards at least one object in a venue through a wireless multipath channel of the venue. The receiver is configured for: receiving a second wireless signal using a plurality of receive antennas through the wireless multipath channel between the transmitter and the receiver. The second wireless signal differs from the first wireless signal due to the wireless multipath channel and a modulation of the first wireless signal by the at least one object. The processor is configured for obtaining a set of channel information (CI) of the wireless multipath channel based on the second wireless signal received by the receiver, and tracking the at least one object simultaneously based on the set of CI. Each CI in the set is associated with a respective one of the plurality of transmit antennas and a respective one of the plurality of receive antennas.