Comparative Testing of Radar Signal Representations when Sensing Though Materials

A paper presentation at Beyond Radar Waves: The First Workshop on Radar-Based Human-Computer Interaction, ACM EICS 2024, Cagliari, Italy.
Authors: Nuwan T. Attygalle, Matjaž Kljun, Una Vuletić and Klen Čopič Pucihar
Abstract: In recent years, gesture recognition using miniaturised radar sensing has attracted attention in both academia and industry. The ability to sense mid-air gestures with miniaturised radars through non-conductive materials with high spatial resolution opens up new opportunities for interacting with systems embedded with such radar technology. Examples include radars embedded in wearables, cars’ dashboard, smart furniture, and other objects within smart environments. However, a deeper understanding of how different occluding materials impact gesture recognition performance is needed. Previous studies have primarily focused on evaluating only one type of radar signal representation, despite the fact that several other representations exist and proved effective. One way to better understand the aforementioned impact of the occluding materials on the radar signal is thus to compare different radar signal representations. To this end, this paper conducts a comparative testing of four (4) signal representations (In-phase and Quadrature (IQ) representations in time and frequency domain, Range-Angles and Range Doppler) in order to evaluate their robustness against signal distortions caused by occluding materials. The preliminary results show that the performance increases with higher transmission coefficient and that compared to IQ, Range-Doppler and Range-Angles signal representations are significantly more robust against distortions caused by occluding materials.