Joint Vital Signs and Position Estimation of Multiple Persons Using SIMO Radar

Respiration rate monitoring using ultra-wideband (UWB) radar is preferred because it provides contactless measurement without restricting the person’s privacy. This study considers a novel non-contact-based solution using a single-input multiple-output (SIMO) UWB impulse radar. In the proposed system, the collected radar data are converted to several narrow-band signals using the generalized Goertzel algorithm (GGA), which are used as the input of the designed phased arrays for position estimation. In this context, we introduce the incoherent signal subspace methods (ISSM) for the direction of arrivals (DOAs) and distance evaluation. Meanwhile, a beam focusing approach is used to determine each individual and estimate their breathing rate automatically based on a linearly constrained minimum variance (LCMV) beamformer. The experimental results prove that the proposed algorithm can achieve high estimation accuracy in a variety of test environments, with an error of 2%, 5%, and 2% for DOA, distance, and respiration rate, respectively.

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Indoor Activity and Vital Sign Monitoring for Moving People with Multiple Radar Data Fusion

Remote Sensing ◽

10.3390/rs13183791 ◽

2021 ◽

Vol 13 (18) ◽

pp. 3791

Author(s):

Xiuzhu Yang ◽

Xinyue Zhang ◽

Yi Ding ◽

Lin Zhang

Keyword(s):

Data Fusion ◽

Vital Sign ◽

Continuous Wave ◽

Short Term Memory ◽

Wavelet Packet ◽

Vital Signs ◽

Radar Data ◽

Activity Monitoring ◽

Ultra Wideband ◽

Additional Information

The monitoring of human activity and vital signs plays a significant role in remote health-care. Radar provides a non-contact monitoring approach without privacy and illumination concerns. However, multiple people in a narrow indoor environment bring dense multipaths for activity monitoring, and the received vital sign signals are heavily distorted with body movements. This paper proposes a framework based on Frequency Modulated Continuous Wave (FMCW) and Impulse Radio Ultra-Wideband (IR-UWB) radars to address these challenges, designing intelligent spatial-temporal information fusion for activity and vital sign monitoring. First, a local binary pattern (LBP) and energy features are extracted from FMCW radar, combined with the wavelet packet transform (WPT) features on IR-UWB radar for activity monitoring. Then the additional information guided fusing network (A-FuseNet) is proposed with a modified generative and adversarial structure for vital sign monitoring. A Cascaded Convolutional Neural Network (CCNN) module and a Long Short Term Memory (LSTM) module are designed as the fusion sub-network for vital sign information extraction and multisensory data fusion, while a discrimination sub-network is constructed to optimize the fused heartbeat signal. In addition, the activity and movement characteristics are introduced as additional information to guide the fusion and optimization. A multi-radar dataset with an FMCW and two IR-UWB radars in a cotton tent, a small room and a wide lobby is constructed, and the accuracies of activity and vital sign monitoring achieve 99.9% and 92.3% respectively. Experimental results demonstrate the superiority and robustness of the proposed framework.

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Accurate Heart Rate and Respiration Rate Detection Based on a Higher-Order Harmonics Peak Selection Method Using Radar Non-Contact Sensors

Sensors ◽

10.3390/s22010083 ◽

2021 ◽

Vol 22 (1) ◽

pp. 83

Author(s):

Hongqiang Xu ◽

Malikeh P. Ebrahim ◽

Kareeb Hasan ◽

Fatemeh Heydari ◽

Paul Howley ◽

...

Keyword(s):

Heart Rate ◽

Signal Processing ◽

Respiration Rate ◽

Body Position ◽

Random Noise ◽

Vital Signs ◽

Ultra Wideband ◽

Spectrum Estimation ◽

Respiration Activity ◽

Uwb Radar

Vital signs such as heart rate and respiration rate are among the most important physiological signals for health monitoring and medical applications. Impulse radio (IR) ultra-wideband (UWB) radar becomes one of the essential sensors in non-contact vital signs detection. The heart pulse wave is easily corrupted by noise and respiration activity since the heartbeat signal has less power compared with the breathing signal and its harmonics. In this paper, a signal processing technique for a UWB radar system was developed to detect the heart rate and respiration rate. There are four main stages of signal processing: (1) clutter removal to reduce the static random noise from the environment; (2) independent component analysis (ICA) to do dimension reduction and remove noise; (3) using low-pass and high-pass filters to eliminate the out of band noise; (4) modified covariance method for spectrum estimation. Furthermore, higher harmonics of heart rate were used to estimate heart rate and minimize respiration interference. The experiments in this article contain different scenarios including bed angle, body position, as well as interference from the visitor near the bed and away from the bed. The results were compared with the ECG sensor and respiration belt. The average mean absolute error (MAE) of heart rate results is 1.32 for the proposed algorithm.

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Experimental research of indoor navigation system based on broadcast signals

Issues of radio electronics ◽

10.21778/2218-5453-2020-5-49-57 ◽

2020 ◽

Vol 49 (5) ◽

pp. 49-57

Author(s):

A. V. Ksendzuk ◽

E. A. Surmin ◽

V. V. Kachesov ◽

S. O. Zhdanov ◽

K. S. Shakhalov

Keyword(s):

Navigation System ◽

Open Space ◽

Position Estimation ◽

Indoor Navigation ◽

Estimation Accuracy ◽

Satellite Systems ◽

Indoor Navigation System ◽

Point To Point ◽

Navigation Signals ◽

Navigation Equipment

Results of an experimental study of a local navigation system based on the processing signals from broadcast sources presented. The results of the development of processing algorithms for point-to-point coordinates estimation of the object are presented. The results of the development of algorithms for trajectories estimation are presented. In performed simulation the possibility of obtaining submeter position estimation accuracy in the proposed system is shown. Development results of the navigation module demonstrator are presented. The results of experimental work in difficult navigation conditions, in the presence of shading, reflections and other factors, are presented. It is shown that the developed navigation module allows in the open space near buildings which partially obscuring the satellite systems signals to obtain accuracy higher than the GNSS navigation equipment. In indoor environment in the absence of satellite navigation signals, the developed module shows positioning accuracy not worse than 1.5 meters and provides a measurement rate 1 Hz and better.

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Extraction and Analysis of Respiratory Motion Using a Comprehensive Wearable Health Monitoring System

Sensors ◽

10.3390/s21041393 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1393

Author(s):

Uduak Z. George ◽

Kee S. Moon ◽

Sung Q. Lee

Keyword(s):

Tidal Volume ◽

Respiration Rate ◽

Spline Interpolation ◽

Vital Signs ◽

Area Under The Curve ◽

Sensor Technology ◽

Wearable Sensor ◽

Lung Sound ◽

Health Monitoring System ◽

Electrocardiogram Ecg

Respiratory activity is an important vital sign of life that can indicate health status. Diseases such as bronchitis, emphysema, pneumonia and coronavirus cause respiratory disorders that affect the respiratory systems. Typically, the diagnosis of these diseases is facilitated by pulmonary auscultation using a stethoscope. We present a new attempt to develop a lightweight, comprehensive wearable sensor system to monitor respiration using a multi-sensor approach. We employed new wearable sensor technology using a novel integration of acoustics and biopotentials to monitor various vital signs on two volunteers. In this study, a new method to monitor lung function, such as respiration rate and tidal volume, is presented using the multi-sensor approach. Using the new sensor, we obtained lung sound, electrocardiogram (ECG), and electromyogram (EMG) measurements at the external intercostal muscles (EIM) and at the diaphragm during breathing cycles with 500 mL, 625 mL, 750 mL, 875 mL, and 1000 mL tidal volume. The tidal volumes were controlled with a spirometer. The duration of each breathing cycle was 8 s and was timed using a metronome. For each of the different tidal volumes, the EMG data was plotted against time and the area under the curve (AUC) was calculated. The AUC calculated from EMG data obtained at the diaphragm and EIM represent the expansion of the diaphragm and EIM respectively. AUC obtained from EMG data collected at the diaphragm had a lower variance between samples per tidal volume compared to those monitored at the EIM. Using cubic spline interpolation, we built a model for computing tidal volume from EMG data at the diaphragm. Our findings show that the new sensor can be used to measure respiration rate and variations thereof and holds potential to estimate tidal lung volume from EMG measurements obtained from the diaphragm.

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A compact dual port UWB-MIMO/diversity antenna for indoor application

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078717001283 ◽

2017 ◽

Vol 10 (3) ◽

pp. 360-367 ◽

Cited By ~ 4

Author(s):

Sonika Priyadarsini Biswal ◽

Sushrut Das

Keyword(s):

Mimo System ◽

Ground Plane ◽

Multiple Input Multiple Output ◽

Open Circuit ◽

Ultra Wideband ◽

Impedance Bandwidth ◽

Good Prospect ◽

Mimo Antenna ◽

Radiating Element ◽

Input Multiple Output

A compact printed quadrant shaped monopole antenna is introduced in this paper as a good prospect for ultra wideband- multiple-input multiple-output (UWB-MIMO) system. The proposed MIMO antenna comprises two perpendicularly oriented monopoles to employ polarization diversity. An open circuit folded stub is extended from the ground plane of each radiating element to enhance the impedance bandwidth satisfying the UWB criteria. Two ‘L’ shaped slots are further etched on the radiator to provide good isolation performance between two radiators. The desirable radiator performances and diversity performances are ensured by simulation and/or measurement of the reflection coefficient, radiation pattern, realized peak gain, envelope correlation coefficient (ECC), diversity gain, mean effective gain (MEG) ratio and channel capacity loss (CCL). Results indicate that the proposed antenna exhibits 2.9–11 GHz 10 dB return loss bandwidth, mutual coupling <−20 dB, ECC < 0.003, MEG ratio ≈ 1, and CCL < 0.038 Bpsec/Hz, making it a good candidate for UWB and MIMO diversity application.

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Experimental Comparison between Event and Global Shutter Cameras

Sensors ◽

10.3390/s21041137 ◽

2021 ◽

Vol 21 (4) ◽

pp. 1137

Author(s):

Ondřej Holešovský ◽

Radoslav Škoviera ◽

Václav Hlaváč ◽

Roman Vítek

Keyword(s):

High Speed ◽

Ground Truth ◽

Motion Blur ◽

Position Estimation ◽

Estimation Accuracy ◽

Experimental Comparison ◽

Estimation Errors ◽

Detection Rates ◽

Ballistic Experiment ◽

Event Camera

We compare event-cameras with fast (global shutter) frame-cameras experimentally, asking: “What is the application domain, in which an event-camera surpasses a fast frame-camera?” Surprisingly, finding the answer has been difficult. Our methodology was to test event- and frame-cameras on generic computer vision tasks where event-camera advantages should manifest. We used two methods: (1) a controlled, cheap, and easily reproducible experiment (observing a marker on a rotating disk at varying speeds); (2) selecting one challenging practical ballistic experiment (observing a flying bullet having a ground truth provided by an ultra-high-speed expensive frame-camera). The experimental results include sampling/detection rates and position estimation errors as functions of illuminance and motion speed; and the minimum pixel latency of two commercial state-of-the-art event-cameras (ATIS, DVS240). Event-cameras respond more slowly to positive than to negative large and sudden contrast changes. They outperformed a frame-camera in bandwidth efficiency in all our experiments. Both camera types provide comparable position estimation accuracy. The better event-camera was limited by pixel latency when tracking small objects, resulting in motion blur effects. Sensor bandwidth limited the event-camera in object recognition. However, future generations of event-cameras might alleviate bandwidth limitations.

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Design of an interlocked four-port MIMO antenna for UWB automotive communications

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078721000374 ◽

2021 ◽

pp. 1-8

Author(s):

M. Saravanan ◽

R. Kalidoss ◽

B. Partibane ◽

K. S. Vishvaksenan

Keyword(s):

Multiple Input Multiple Output ◽

Performance Estimation ◽

Ultra Wideband ◽

Antenna Element ◽

Frequency Range ◽

Mimo Antenna ◽

Multiple Input ◽

Input Multiple Output ◽

Operating Bandwidth ◽

Peak Gain

Abstract The design, analysis, fabrication, and testing of a four-port multiple-input multiple-output (MIMO) antenna is reported in this paper for automotive communications. The MIMO antenna is constructed using the basic antenna element exploiting a slot geometry. Two such antennas are developed on the same microwave laminate to develop a two-port MIMO antenna. Two such microwave laminates are interlocked to create the four-port MIMO scheme. The most distinct feature of the proposed architecture is that the inter-port isolation is well-taken care without the need for an external decoupling unit. The four-port MIMO antenna has an overall volume of 32 × 15 × 32 mm3. The prototype MIMO antenna is fabricated and the measurements are carried out to validate the simulation results. The antenna offers ultra-wideband (UWB) characteristics covering the frequency range of 2.8–9.5 GHz. The average boresight gain of the antenna ranges from 3.2 to 5.41 dBi with the peak gain at 8 GHz. The simulated efficiency of the antenna is greater than 73% within the operating bandwidth. The MIMO parameters such as envelope correlation coefficient, diversity gain, and mean effective gain are evaluated and presented. The appropriateness of the proposed antenna for deployment in the shark fin housing of the present-day automobiles is verified using on-car performance estimation.

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Location-Aided Uplink Transmission for User-Centric Cell-Free Massive MIMO Systems: A Fairness Priority Perspective

10.21203/rs.3.rs-1202385/v1 ◽

2022 ◽

Author(s):

Chen Wei ◽

Kui Xu ◽

Zhexian Shen ◽

Xiaochen Xia ◽

Wei Xie ◽

...

Keyword(s):

Large Scale ◽

Mean Squared Error ◽

Mimo Systems ◽

Multiple Input Multiple Output ◽

Access Point ◽

Estimation Accuracy ◽

Minimum Mean Squared Error ◽

Input Multiple Output ◽

User Centric ◽

Assignment Scheme

Abstract In this paper, we investigate the uplink transmission for user-centric cell-free massive multiple-input multiple-output (MIMO) systems. The largest-large-scale-fading-based access point (AP) selection method is adopted to achieve a user-centric operation. Under this user-centric framework, we propose a novel inter-cluster interference-based (IC-IB) pilot assignment scheme to alleviate pilot contamination. Considering the local characteristics of channel estimates and statistics, we propose a location-aided distributed uplink combining scheme based on a novel proposed metric representing inter-user interference to balance the relationship among the spectral efficiency (SE), user equipment (UE) fairness and complexity, in which the normalized local partial minimum mean-squared error (LP-MMSE) combining is adopted for some APs, while the normalized maximum ratio (MR) combining is adopted for the remaining APs. A new closed-form SE expression using the normalized MR combining is derived and a novel metric to indicate the UE fairness is also proposed. Moreover, the max-min fairness (MMF) power control algorithm is utilized to further ensure uniformly good service to the UEs. Simulation results demonstrate that the channel estimation accuracy of our proposed IC-IB pilot assignment scheme outperforms that of the conventional pilot assignment schemes. Furthermore, although the proposed location-aided uplink combining scheme is not always the best in terms of the per-UE SE, it can provide the more fairness among UEs and can achieve a good trade-off between the average SE and computational complexity.

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Prototyping Sensor Network System for Automatic Vital Signs Collection

Methods of Information in Medicine ◽

10.3414/me12-01-0096 ◽

2013 ◽

Vol 52 (03) ◽

pp. 239-249 ◽

Cited By ~ 13

Author(s):

H. Noma ◽

C. Naito ◽

M. Tada ◽

H. Yamanaka ◽

T. Takemura ◽

...

Keyword(s):

Sensor Network ◽

Vital Sign ◽

Paired Comparison ◽

Estimation Error ◽

Vital Signs ◽

Position Estimation ◽

University Hospital ◽

Network System ◽

Sensing System ◽

Proximity Sensing

SummaryObjective: Development of a clinical sensor network system that automatically collects vital sign and its supplemental data, and evaluation the effect of automatic vital sensor value assignment to patients based on locations of sensors.Methods: The sensor network estimates the data-source, a target patient, from the position of a vital sign sensor obtained from a newly developed proximity sensing system. The proximity sensing system estimates the positions of the devices using a Bluetooth inquiry process. Using Bluetooth access points and the positioning system newly developed in this project, the sensor network collects vital sign and its 4W (who, where, what, and when) supplemental data from any Blue-tooth ready vital sign sensors such as Continua-ready devices. The prototype was evaluated in a pseudo clinical setting at Kyoto University Hospital using a cyclic paired comparison and statistical analysis.Results: The result of the cyclic paired analysis shows the subjects evaluated the proposed system is more effective and safer than POCS as well as paper-based operation. It halves the times for vital signs input and eliminates input errors. On the other hand, the prototype failed in its position estimation for 12.6% of all attempts, and the nurses overlooked half of the errors. A detailed investigation clears that an advanced interface to show the system’s “confidence”, i.e. the probability of estimation error, must be effective to reduce the oversights.Conclusions: This paper proposed a clinical sensor network system that relieves nurses from vital signs input tasks. The result clearly shows that the proposed system increases the efficiency and safety of the nursing process both subjectively and objectively. It is a step toward new generation of point of nursing care systems where sensors take over the tasks of data input from the nurses.

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Ultra-Wideband Chaos Life-Detection Radar with Sinusoidal Wave Modulation

International Journal of Bifurcation and Chaos ◽

10.1142/s0218127417300464 ◽

2017 ◽

Vol 27 (13) ◽

pp. 1730046 ◽

Cited By ~ 5

Author(s):

Hang Xu ◽

Ying Li ◽

Jianguo Zhang ◽

Hong Han ◽

Bing Zhang ◽

...

Keyword(s):

Dynamic Range ◽

Vital Signs ◽

Radar System ◽

Ultra Wideband ◽

Thick Wall ◽

Sinusoidal Wave ◽

Echo Signal ◽

Range Resolution ◽

Life Detection ◽

Lock In

We propose and experimentally demonstrate an ultra-wideband (UWB) chaos life-detection radar. The proposed radar transmits a wideband chaotic-pulse-position modulation (CPPM) signal modulated by a single-tone sinusoidal wave. A narrow-band split ring sensor is used to collect the reflected sinusoidal wave, and a lock-in amplifier is utilized to identify frequencies of respiration and heartbeat by detecting the phase change of the sinusoidal echo signal. Meanwhile, human location is realized by correlating the CPPM echo signal with its delayed duplicate and combining the synthetic aperture technology. Experimental results demonstrate that the human target can be located accurately and his vital signs can be detected in a large dynamic range through a 20-cm-thick wall using our radar system. The down-range resolution is 15[Formula: see text]cm, benefiting from the 1-GHz bandwidth of the CPPM signal. The dynamic range for human location is 50[Formula: see text]dB, and the dynamic ranges for heartbeat and respiration detection respectively are 20[Formula: see text]dB and 60[Formula: see text]dB in our radar system. In addition, the bandwidth of the CPPM signal can be adjusted from 620[Formula: see text]MHz to 1.56[Formula: see text]GHz to adapt to different requirements.

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