Qijun Wang

Making invisiblesignals legible.

PhD Candidate in Computer Science and Engineering
Michigan State University

I design batteryless RF devices and recovery methods that turn minute vibrations and weak radio measurements into speech, keystrokes, and movement. These systems also reveal where wireless perception crosses physical and privacy boundaries.

First-author work at IEEE S&P, IEEE INFOCOM, and ACM UbiComp.

Curriculum vitae Google Scholar Email

See the research in motion

Research in motion

Passive wireless systems that see, hear, and track.

Four systems connect batteryless RF devices, difficult sensing environments, signal recovery, and the privacy boundaries of wireless perception.

Real demonstrations from four representative systems.

Selected research

Representative systems

Together, these systems connect passive RF devices and resonators with signal recovery, deployment in complex environments, and wireless privacy.

IEEE S&P 2026

RadKey

Privacy boundary

Demonstrates keystroke inference across a wall from minute vibrations captured by a concealed batteryless tag.

Key result: 90.5% F1 at 8 m under obstructed line of sight with LLM-guided adaptation.

Paper ↗

ACM IMWUT / UbiComp 2026

SOPAR

Sensing in complex environments

Extends passive RF sensing into dense beehives by tracking tagged bees with a millimeter-scale resonator.

Key result: 3.7 cm median error tracking a queen bee in a full-size hive.

Paper ↗

IEEE INFOCOM 2026

RadEar

Signal recovery

Demonstrates recovery and separation of overlapping voices from weak RF backscatter captured across a physical barrier.

Key result: STOI ≥ 0.67 through a 15 cm concrete wall at speaker-to-tag distances up to 2.5 m.

Paper ↗

ACM IMWUT / UbiComp 2025

TagMic

Batteryless wireless microphone

Establishes a passive RF interface for continuous acoustic sensing without an onboard battery.

Key result: Intelligible, continuous batteryless voice streaming at up to 8 m.

Paper ↗

Research

Research areas

Passive Sensing Interfaces

Batteryless RF devices that capture sound, vibration, and movement without an onboard battery.

Selected systems SOPAR TagMic

Signal Recovery from Weak RF Measurements

Signal processing and learning methods that recover speech, keystrokes, and motion from weak RF measurements.

Selected systems RadKey RadEar TagMic

Privacy Boundaries of Wireless Perception

Analyses that reveal what wireless systems can infer across walls and other physical barriers.

Selected systems RadKey RadEar RadSee

Publications

Research publications

My work on passive RF sensing and wireless perception has appeared in venues spanning mobile systems, ubiquitous computing, and security. Google Scholar ↗

2026IEEE S&P