HBR-Radio Design Overview
HBR-Radio works passively, where it utilizes existing Wi-Fi signals, as Wi-Fi routers are nearly in every household and facility. A visual illustration that clarifies the general processes of the HBR-Radio working methodology is shown in the Figure below. The whole monitoring process is composed of two sections, first is the transmitter which is the Wi-Fi router that radiates in all directions. The second section is the receiver where two receiving antennas are connected to the same radio receiver. Those antennas are utilized to capture both the reference signal from the Wi-Fi access point and the surveillance signal reflected from the human. After that, both signals are processed to obtain the vital sign signal. Finally, the results are displayed through a user-friendly interface.
HBR-Radio Visual Design
The proposed system operates at 5GHz band following 802.11 protocol. The purpose of utilizing this frequency band is to allow for the detection of the minute movements caused by heartbeats and breathing. To illustrate, the wavelength associated with the 5GHz frequency can detect the vital sign information. HBR-Radio consists of two directional antennas connected to the software defined radio (SDR) to capture both reference and surveillance signals. Following that is the channel scanner which ensures that the system is functioning on the occupied channel of the access point. Then the DSP system is built via MATLAB, ending with the interface design for displaying the results. Each design aspect is discussed in detail in this section.
Block Diagram for Analog Receiver Frontend