Continuous Multi-user Activity Tracking via Room-Scale mmWave Sensing

TL;DR

This paper introduces MARS, a system using a single COTS mmWave radar to continuously detect and track multiple users' macro and micro activities in smart spaces with high accuracy and low latency.

Contribution

It presents a novel holistic system that combines intelligent modeling and dynamic spatial time sharing for multi-user activity sensing using mmWave radar.

Findings

Achieves over 94% weighted F1-Score in activity inference

Handles five subjects and 19 activities simultaneously

Responds within approximately 2 seconds

Abstract

Continuous detection of human activities and presence is essential for developing a pervasive interactive smart space. Existing literature lacks robust wireless sensing mechanisms capable of continuously monitoring multiple users' activities without prior knowledge of the environment. Developing such a mechanism requires simultaneous localization and tracking of multiple subjects. In addition, it requires identifying their activities at various scales, some being macro-scale activities like walking, squats, etc., while others are micro-scale activities like typing or sitting, etc. In this paper, we develop a holistic system called MARS using a single Commercial off the-shelf (COTS) Millimeter Wave (mmWave) radar, which employs an intelligent model to sense both macro and micro activities. In addition, it uses a dynamic spatial time sharing approach to sense different subjects simultaneously. A thorough evaluation of MARS shows that it can infer activities continuously with a weighted F1-Score of > 94% and an average response time of approx 2 sec, with 5 subjects and 19 different activities.