LiveTag: Sensing Human-Object Interaction through Passive Chipless WiFi Tags


Chuhan Gao and Yilong Li, University of Wisconsin-Madison; Xinyu Zhang, University of California San Diego


Many types of human activities involve interaction with passive objects. Thus, by wirelessly sensing human interaction with them, one can infer activities at a fine resolution, enabling a new wave of ubiquitous computing applications. In this paper, we propose LiveTag to achieve this vision. LiveTag is a fully passive, thin metal tag that can be printed on paper-like substrates and attached on objects. It has no batteries, silicon chips or discrete electronic components. But when touched by fingers, it disturbs ambientWiFi channel in a deterministic way. Multiple metallic structures can be printed on the same tag to create unique touch points. Further, LiveTag incorporates customized multi-antenna beamforming algorithms that allow WiFi receivers to sense the tag and discriminate the touch events, amid multipath reflections/interferences. Our prototypes of LiveTag have verified its feasibility and performance. We have further applied LiveTag to real-world usage scenarios to showcase its effectiveness in sensing human-object interaction.

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@inproceedings {211253,
author = {Chuhan Gao and Yilong Li and Xinyu Zhang},
title = {{LiveTag}: Sensing {Human-Object} Interaction through Passive Chipless {WiFi} Tags},
booktitle = {15th USENIX Symposium on Networked Systems Design and Implementation (NSDI 18)},
year = {2018},
isbn = {978-1-939133-01-4},
address = {Renton, WA},
pages = {533--546},
url = {},
publisher = {USENIX Association},
month = apr

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