Hydra: Exploiting Multi-Bounce Scattering for Beyond-Field-of-View mmWave Radar
Published in The 30th Annual International Conference on Mobile Computing and Networking (ACM Mobicom), 2024
Abstract
In this paper, we ask, “Can millimeter-wave (mmWave) radars sense objects not directly illuminated by the radar - for instance, objects located outside the transmit beamwidth, behind occlusions, or placed fully behind the radar?” Traditionally, mmWave radars are limited to sense objects that are directly illuminated by the radar and scatter its signals directly back. In practice, however, radar signals scatter to other intermediate objects in the environment and undergo multiple bounces before being received back at the radar. In this paper, we present Hydra, a framework to explicitly model and exploit multi-bounce paths for sensing. Hydra enables standalone mmWave radars to sense beyond-field-of-view objects without prior knowledge of the environment. We extensively evaluate the localization performance of Hydra with an off-the-shelf mmWave radar in five different environments with everyday objects. Exploiting multi-bounce via Hydra provides 2×-10× improvement in the median beyond-field-of-view localization error over baselines.
Recommended citation: Nishant Mehrotra, Divyanshu Pandey, Akarsh Prabhakara, Yawen Liu, Swarun Kumar, and Ashutosh Sabharwal. 2024. Hydra: Exploiting Multi-Bounce Scattering for Beyond-Field-of-View mmWave Radar. In Proceedings of the 30th Annual International Conference on Mobile Computing and Networking (ACM MobiCom ‘24). Association for Computing Machinery, New York, NY, USA, 1545–1559. https://doi.org/10.1145/3636534.3690710