Extracting Range-Doppler Information of Moving Targets from Wi-Fi Channel State Information

2025-08-04

AI Summary

This work addresses the joint range-Doppler estimation inaccuracy in commodity Wi-Fi CSI sensing, caused by hardware asynchrony and strong transceiver antenna coupling. We propose three key techniques: time-offset elimination, phase alignment correction, and transceiver coupling suppression—enabling, for the first time, high-precision joint range and velocity estimation of moving targets using a single-station, non-full-duplex Wi-Fi system. Our method operates directly on phase measurements extracted from off-the-shelf network interface cards, applying signal processing to compensate for hardware-induced errors and suppress coupling artifacts. Experiments in real-world environments achieve centimeter-level range accuracy and sub-meter-per-second velocity accuracy, supporting reliable target detection and continuous tracking. This work breaks the reliance of Wi-Fi sensing on customized hardware, demonstrating the feasibility of low-cost, high-precision wireless sensing using commodity infrastructure.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Computer Vision: Motion & Tracking
• Intelligent Robots: State Estimation

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Security and Privacy: Large-scale security measurements
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

This paper presents, for the first time, a method to extract both range and Doppler information from commercial Wi-Fi Channel State Information (CSI) using a monostatic (single transceiver) setup. Utilizing the CSI phase in Wi-Fi sensing from a Network Interface Card (NIC) not designed for full-duplex operation is challenging due to (1) Hardware asynchronization, which introduces significant phase errors, and (2) Proximity of transmit (Tx) and receive (Rx) antennas, which creates strong coupling that overwhelms the motion signal of interest. We propose a new signal processing approach that addresses both challenges via three key innovations: Time offset cancellation, Phase alignment correction, and Tx/Rx coupling mitigation. Our method achieves cm-level accuracy in range and Doppler estimation for moving targets, validated using a commercial Intel Wi-Fi AX211 NIC. Our results show successful detection and tracking of moving objects in realistic environments, establishing the feasibility of high-precision sensing using standard Wi-Fi packet communications and off-the-shelf hardware without requiring any modification or specialized full-duplex capabilities.

Problem

• Extract range and Doppler data from Wi-Fi CSI
• Overcome hardware asynchronization and phase errors
• Mitigate Tx/Rx antenna coupling for motion detection

Innovation

• Time offset cancellation for phase error reduction
• Phase alignment correction for signal accuracy
• Tx/Rx coupling mitigation to isolate motion signals