Passive Human Sensing Enhanced by Reconfigurable Intelligent Surface: Opportunities and Challenges
Xinyu Li, Jian Wei You, Ze Gu, Qian Ma, Long Chen, Jingyuan Zhang, Shi Jin, Tie Jun Cui
Abstract
Reconfigurable intelligent surfaces (RISs) have flexible and exceptional performance in manipulating electromagnetic waves and customizing wireless channels. These capabilities enable them to provide a plethora of valuable activity-related information for promoting wireless human sensing. In this article, we present a comprehensive overview of passive human sensing using radio-frequency signals with the assistance of RISs. Specifically, based on the specific applications, we categorize the state-of-the-art human sensing techniques into three types, including human imaging, localization, and activity recognition. Meanwhile, we would also summarize the strengths and weaknesses of the existing RIS-empowered human sensing systems. Furthermore, we explore the application of RISs in human micro-motion sensing, and propose a vital-sign monitoring system enhanced by RISs. Some preliminary experiments are presented to demonstrate the potential of RISs in contactless multiperson vital-sign sensing. Finally, we discuss the technical challenges and opportunities in this field.