RF Breathing Rate Estimation Using CSI Phase Spectra
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Solution Overview
Problem
Existing technologies have not effectively utilized radio frequency (RF) signals for applications beyond wireless communication, particularly for determining breathing rates in the presence of RF signals.
Innovation Solution
The method involves obtaining channel state information (CSI) from RF signals, extracting phase information, and analyzing frequency spectra to determine breathing rates using algorithms that process CSI from one or multiple subcarriers, leveraging existing RF communication devices like Wi-Fi equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If RF signals are used for wireless communication, then network connectivity is provided, but the ability to detect breathing rates is not achieved
Solution Approach 1:
The patent applies universality by enabling RF communication devices to perform dual functions: wireless communication and breathing rate detection. The system processes RF signals to extract both communication data and physiological information, allowing a single device to serve multiple purposes without requiring specialized equipment.
Solution Approach 2:
The patent introduces channel state information (CSI) as an intermediary that bridges communication and sensing functions. CSI is naturally generated during RF communication and serves as a mediator that contains phase information about the propagation channel, which can be analyzed to detect breathing rates without interfering with the primary communication function.
2Measurement precision
If specialized sensing equipment is used for breathing rate detection, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies self-service by enabling existing RF communication devices to perform breathing rate detection using their own transmitted signals and received CSI. The system uses the communication infrastructure itself to gather sensing data, eliminating the need for separate specialized sensors or equipment.
Solution Approach 2:
The patent replaces mechanical or specialized sensing hardware with signal processing methods. Instead of using physical sensors to detect chest movements, the system uses RF signal phase analysis to infer breathing rates, substituting a complex hardware-based approach with a software-based signal processing solution.
3Ease of operation
If RF signals are present in the environment, then wireless communication is enabled, but breathing rate determination becomes difficult
Solution Approach 1:
The patent converts the presence of RF signals, which was previously a challenge for breathing detection, into a benefit. The system uses the same RF signals that enable communication to also provide the phase information needed for breathing rate detection, turning a potential source of interference into a useful sensing resource.
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 real-time breathing rate estimation using common RF communication devices without specialized equipment, providing accurate breathing rate detection through phase change analysis in frequency spectra.
Implementation Method 1
phase information of the CSI can be analyzed to determine the breathing rate
Data Source
AI summary
In some implementations, a device may obtain channel state information (CSI) corresponding to each subcarrier of a plurality of subcarriers in a set of RF transmissions comprising at least the plurality of subcarriers. The device may extract phase information of the CSI corresponding to each subcarrier and determine, for each subcarrier, a frequency spectrum from the phase information of the CSI, where the frequency spectrum comprises phase change values of the CSI corresponding to the respective subcarrier for a plurality of frequencies. The device may determine a breathing rate from the frequency spectrum of the CSI corresponding to a subcarrier set comprising one or more of the subcarriers, the breathing rate corresponding to a phase change value in the frequency spectrum within a predetermined range of frequencies for breathing rates. The device may output an indication of the determined breathing rate.