Bidirectional CSI Sensing for Phase-Offset-Free Vital Detection
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Solution Overview
Problem
Existing non-contact sensing methods, such as those using Wi-Fi RSS for breathing frequency detection, suffer from low accuracy due to phase offset phenomena and insufficient adaptability, leading to poor detection performance.
Innovation Solution
A non-contact sensing method that utilizes channel state information (CSI) from both directions of a communication link to construct third CSI, mitigating phase and amplitude offsets, thereby improving sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Wi-Fi RSS is used for breathing frequency detection, then the detection can be performed non-contactly, but the detection accuracy is low due to phase offset phenomena
Solution Approach 1:
The patent combines CSI data from both transmission directions (first node to second node, and second node to first node) to construct third CSI. This merging of bidirectional channel information allows the system to eliminate phase and amplitude offsets through comparative analysis, thereby resolving the phase offset phenomenon that limits RSS-based detection accuracy.
Solution Approach 2:
The patent transitions from using unidirectional RSS or single-direction CSI to utilizing bidirectional CSI data. By adding the dimension of reverse-direction channel state information, the system creates a more comprehensive measurement space that enables offset cancellation and improves breathing frequency detection precision.
2Reliability
If unidirectional CSI is used for sensing, then the system complexity is low, but the sensing performance is poor due to phase and amplitude offsets
Solution Approach 1:
The patent merges first CSI and second CSI from opposite transmission directions to construct third CSI. This combination approach improves sensing reliability by eliminating phase and amplitude offsets through the reciprocity relationship between forward and reverse channel measurements, while the processing complexity remains manageable due to the systematic construction method.
Solution Approach 2:
The patent utilizes feedback from the reverse-direction channel measurement (second CSI) to correct the forward-direction channel information (first CSI). By comparing and processing both directions of channel state information, the system eliminates offsets and improves sensing reliability through a feedback-based correction mechanism.
3Adaptability or versatility
If existing non-contact sensing methods are used, then the implementation is simple, but the adaptability is insufficient for different scenarios
Solution Approach 1:
The patent creates a universal sensing approach that works for both single-antenna and multi-antenna devices by using bidirectional CSI construction. The method of combining first CSI and second CSI to eliminate offsets is applicable across different device configurations and scenarios, providing enhanced adaptability without requiring scenario-specific customization.
Solution Approach 2:
The patent changes the fundamental parameter used for sensing from unidirectional RSS or single-direction CSI to bidirectional third CSI. This parameter transformation enables the system to adapt to different scenarios (breathing detection, posture recognition, etc.) while maintaining consistent offset elimination performance, thereby improving versatility without proportionally increasing complexity.
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 method enhances the accuracy of detecting physiological indicators and human body postures by eliminating phase and amplitude offsets, applicable to both single-antenna and multi-antenna devices.
Implementation Method 1
first CSI is CSI of a link from a first node to a second node, and the second CSI is CSI of a link from the second node and the first node
Data Source
AI summary
This application discloses a non-contact sensing method and apparatus, to improve target sensing performance. The method includes: obtaining first information, where the first information is associated with first channel state information (CSI) and second CSI of a first frequency, the first CSI is CSI of a link from a first node to a second node, and the second CSI is CSI of a link from the second node and the first node; and determining a sensing feature of a target based on the first information.