Project Details
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Robust Reconstruction for Body Area Wireless Sensor Networks (RoReyBaN)

Subject Area Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
Security and Dependability, Operating-, Communication- and Distributed Systems
Term from 2018 to 2025
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 399332937
 
Final Report Year 2024

Final Report Abstract

The aging population requires new and innovative approaches to monitor and supervise medical and physical conditions in residential and rehabilitation environments. One of the essential medical devices for this purpose is the electrocardiogram (ECG), which measures heart activity on the body surface. However, the use of ECG measurements outside of controlled clinical settings is often corrupted by motion artifacts resulting from freedom of movement. In this project, motion artifacts in ECG are closely examined. We study the spectral characteristics of motion artifacts for a set of different motions representing everyday activities. Furthermore, we investigate to what extent reference motion sensors (accelerometer, gyroscope, and skin-electrode impedance) are able to characterize and remove the recorded motion artifacts from the measurements. Our results demonstrate that motion artifacts markedly change their characteristics with a change in motion. While low-intensity movements manifest in lower frequency bands, higher intensity exercises provoke motion artifacts that are much more complex in their composition. These characteristics are correspondingly reflected in the correlation between reference sensors and artifacts. To characterize and remove motion artifacts in mobile measurements, we use canonical polyadic decomposition (CPD) along with measurements obtained from different reference sensors. Wavelet transformation is utilized to transform ECG and reference data from vector to matrix format. Next, a 3D tensor is constructed by combining the heterogeneous measurements. We propose a methodology to predict the decomposition rank based on statistical features in the ECG that quantify the signal quality. To evaluate the performance of the decomposition process, we combine isolated motion artifacts recorded at the back with ECG obtained in rest to generate artificially corrupted data. The results suggest that CPD successfully removes motion artifacts from the data for all reference sensors regarded. For the statistical modeling of artifacts in ECG data, the joint distribution of the underlying stochastic processes is very relevant. During the investigation of different copulae for modeling dependencies in ECG data, we found the possibility to apply these methods and tools to the wireless sensor network itself. This shows that interdisciplinary research can lead to new approaches. Indeed, it turns out that dependency modeling allows to design reliable wireless systems. Based on the measurements of marginal distributions, it is possible to derive worst-case and best-case performance bounds. Within this project, we brought the concepts of dependency modeling to wireless communications and derived new bounds for multi-antenna and multi-user systems.

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