基于WiFi6 MU-MIMO的非接触人体呼吸监测方法

Non-contact Human Respiratory Monitoring Method Based on WiFi6 MU-MIMO

WiFi6技术中引入多用户多输入输出(Multi-User Multiple Input Multiple Output,MU-MIMO)技术,作为支持多用户并发数据传输的重要手段。借用该技术中的多波束生成方法,可实现对人体呼吸的非接触式监测,从而避免传统佩戴式传感器引入的各种不便。利用双波束相干检测实现对人体呼吸频率的测量,借助WiFi6接入点(Access Point,AP)波束赋形功能将探测信号汇聚在两个波束;AP根据接收机测量到的两个波束功率差别,调整两个波束各子载波的功率大小,实现两个波束在接收机端的各子载波幅度相等;AP补偿两波束因路程差造成的固定相位差,使得人体呼吸引起的两波束周期性相位差转化为相干信号强度的周期性变化,实现了对人体呼吸微弱信号的提取,获得了人体呼吸频率,相对于传统方法可以得到更高的信号质量和更好的信噪比。

The introduction of Multi-User Multiple Input Multiple Output(MU-MIMO)technology is an important means of supporting concurrent data transmission for multiple users in WiFi 6 technology.By utilizing the multi-beam generation method in this technology,non-contact monitoring of human respiration can be achieved,thereby avoiding various inconveniences caused by traditional wearable sensors.This method utilizes coherent detection with dual-beam to measure human respiratory rate.Firstly,the detection signal is converged onto two beams through the beamforming feature of WiFi6 Access Point(AP).Secondly,the AP adjusts the power of subcarriers in each beam based on the power difference between the two beams measured by the receiver to achieve equal amplitudes of subcarriers at the receiver end.Finally,the AP compensates for the fixed phase difference caused by the distance difference between the two beams,converting the periodic phase difference caused by human breathing into a periodic change in coherent signal strength,thus achieving the extraction of weak respiratory signals and obtaining the human respiratory rate.This method can obtain higher signal quality and better signal-to-noise ratio compared to traditional methods.