Through-Wall Multi-Subject Localization and Vital Signs Monitoring Using UWB MIMO Imaging Radar
Abstract
:1. Introduction
- We derive the relationship between vital signs signal and radar image in theory. It is proved that the thorax movement caused by respiration and heartbeat is linear with the phase of the radar image. The signal-to-noise ratio (SNR) of the extracted vital signs signal is improved by the factor of radar channel number times frequency number compared with CW Doppler radars;
- We develop a processing scheme for through-wall multi-subject localization and vital signs separation. To localize multiple subjects through the wall, we introduce the higher-order cumulant (HOC) for 3-D radar imaging. The HOC-based localization significantly enhances the human body by suppressing the background clutter;
- We apply the VMD algorithm with a new grouping criterion to adaptively separate the respiration and heartbeat patterns by combining the decomposed intrinsic mode functions (IMFs) and the residual. The grouping criterion exploits the center frequency of each mode to separate the heartbeat pattern from the respiration harmonics.
2. Materials and Methods
2.1. System Model
2.2. Scheme and Method
2.2.1. Multiple Subjects Detection and Localization
2.2.2. Respiration and Heartbeat Patterns Separation
2.3. Experiments
2.3.1. Measurement Equipment and Parameters
2.3.2. Measurements Setup and Scenarios
3. Results
3.1. Detection and Localization Results
3.2. Vital Signs Separation Results
4. Discussion
5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
Abbreviations
AD | Arctangent demodulation |
BSS | Blind source separation |
BP | Back-projection |
CEEMDAN | Complete ensemble empirical mode decomposition with adaptive noise |
CFAR | Constant false alarm rate |
CW | Continuous-wave |
DACM | Differentiate and cross multiply |
DC | Direct Current |
ECG | Electrocardiogram |
EMD | Empirical mode decomposition |
EEMD | Ensemble empirical mode decomposition |
FMCW | Frequency-modulated continuous-wave |
HOC | Higher-order cumulant |
HR | Heart rate |
IIR | Infinite impulse response |
IMF | Intrinsic mode function |
IR-UWB | Impulse radio ultra-wideband |
MIMO | Multiple-input multiple-output |
RMSE | Root mean square error |
RR | Respiratory rate |
SFCW | Stepped-frequency continuous-wave |
STFT | Short-time Fourier transform |
SIMO | Single-input multiple-output |
SNR | Signal-to-noise ratio |
UWB | Ultra-wideband |
VMD | Variational mode decomposition |
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Configuration | Waveform | Frequency (GHz) | No. of Subjects | Detection Range (m) | Through-Wall | Measured Parameters |
---|---|---|---|---|---|---|
SISO [8] | CW | 24.17 | 1 | 0.2 | - | Breathing and heart sound waveforms |
SISO [14] | CW | 5.8 | 1 | 0.5 | - | Heart sound waveforms and HR |
SISO [35] | IR-UWB | 1.5–4.5 | 1 | 0.8 | - | RR and HR |
SISO [19] | IR-UWB | 6.54–8.04 | 2 | 2 | - | RR and HR |
SISO [31] | IR-UWB | 0.4 | 1 | 3–12 | Yes | Range detection, RR and HR |
SISO [12] | FMCW | 5.46–7.25 | 3 | 1–8 | Yes | RR and HR |
SISO [21] | FMCW | 24–24.25 | 2 | 1.3–3 | - | Range detection, RR and HR |
SISO [23] | FMCW | 7.3–8.05 | 2 | 2.6–5.4 | - | Range detection, RR and HR |
SISO [34] | FMCW | 114–130 | 2 | 1.2–1.6 | - | Range detection, respiration pattern, heartbeat pattern, RR and HR |
SIMO (1T × 8R) [24] | CW | 5.8 | 3 | 2 | - | Angle detection, respiration waveform and RR |
SIMO (1T × 4R) [33] | CW | 2.49 | 2 | 1.68–1.87 | Yes | Angle detection, respiration waveform and RR |
MIMO (2T × 2R) [25] | IR-UWB | 0.7–7 | 2 | 0.4–1.5 | - | 2-D Localization, RR and HR |
MIMO (2T × 8R) [27] | FMCW | 115–123 | 2 | 1.8–2.3 | - | 3-D Localization, RR and HR |
MIMO (10T × 10R) [This work] | SFCW | 1.75–2.25 | 3 | 2.0–2.5 | Yes | 3-D Localization, respiration pattern, heartbeat pattern, RR and HR |
Parameters | Value |
---|---|
transmitting wave mode | SFCW |
center frequency | 2 |
bandwidth | 500 |
frequency step | 4 |
power of transmitted signal | 20 dBm |
frame rate | 20 |
antenna element number | 10 Tx, 10 Rx |
array size | |
antenna element gain | 5dB–6dB |
beam width of each antenna element ( 3 dB) |
Truth (m) | Estimation (m) | Error (m) | ||
---|---|---|---|---|
Line-of-sight | Subj. 1 | (−0.50, 2.50, −0.10) | (−0.44, 2.51, −0.26) | (0.06, 0.01, −0.16) |
Subj. 2 | (0, 2.50, −0.06) | (0.06, 2.51, 0.05) | (0.06, 0.01, 0.11) | |
Subj. 3 | (0.50, 2.50, 0.05) | (0.69, 2.52, 0.16) | (0.19, 0.02, 0.11) | |
Through-wall | Subj. 1 | (−0.3, 2.00, −0.10) | (−0.19, 1.88, −0.26) | (0.11, −0.12, −0.16) |
Subj. 2 | (0.50, 2.00, −0.06) | (0.44, 2.06, 0.16) | (−0.06, 0.06, 0.22) | |
Subj. 3 | (1.00, 2.00, 0.05) | (1.07, 1.97, −0.16) | (0.07, −0.03, −0.21) |
Subject | RMSE (bpm) | |||
---|---|---|---|---|
RR without Wall | RR with Wall | HR without Wall | HR with Wall | |
Subj. 1 | 0.8565 | 1.1757 | 2.2209 | 3.5461 |
Subj. 2 | 0.7058 | 1.2485 | 2.8609 | 4.0297 |
Subj. 3 | 0.9571 | 1.2701 | 2.8079 | 3.4779 |
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Li, Z.; Jin, T.; Dai, Y.; Song, Y. Through-Wall Multi-Subject Localization and Vital Signs Monitoring Using UWB MIMO Imaging Radar. Remote Sens. 2021, 13, 2905. https://doi.org/10.3390/rs13152905
Li Z, Jin T, Dai Y, Song Y. Through-Wall Multi-Subject Localization and Vital Signs Monitoring Using UWB MIMO Imaging Radar. Remote Sensing. 2021; 13(15):2905. https://doi.org/10.3390/rs13152905
Chicago/Turabian StyleLi, Zhi, Tian Jin, Yongpeng Dai, and Yongkun Song. 2021. "Through-Wall Multi-Subject Localization and Vital Signs Monitoring Using UWB MIMO Imaging Radar" Remote Sensing 13, no. 15: 2905. https://doi.org/10.3390/rs13152905
APA StyleLi, Z., Jin, T., Dai, Y., & Song, Y. (2021). Through-Wall Multi-Subject Localization and Vital Signs Monitoring Using UWB MIMO Imaging Radar. Remote Sensing, 13(15), 2905. https://doi.org/10.3390/rs13152905