WiRainbow: Single-Antenna Direction-Aware Wi-Fi Sensing via Dispersion Effect

TL;DR

WiRainbow introduces a single-antenna Wi-Fi sensing method that uses dispersion effects and innovative antenna design to accurately estimate target direction without complex antenna arrays.

Contribution

The paper presents WiRainbow, a novel single-antenna approach leveraging dispersion effects and a coupled-resonator antenna design for direction-aware Wi-Fi sensing.

Findings

Achieves accurate direction estimation in multipath environments

Expands sensing coverage with improved antenna design

Demonstrates robustness and cost-effectiveness in real-world tests

Abstract

Recently, Wi-Fi signals have emerged as a powerful tool for contactless sensing. During the sensing process, obtaining target direction information can provide valuable contextual insights for various applications. Existing direction estimation methods typically rely on antenna arrays, which are costly and complex to deploy in real-world scenarios. In this paper, we present WiRainbow, a novel approach that enables single-antenna-based direction awareness for Wi-Fi sensing by leveraging the dispersion effect of frequency-scanning antennas (FSAs), which can naturally steer Wi-Fi subcarriers toward distinct angles during signal transmission. To address key challenges in antenna design and signal processing, we propose a coupled-resonator-based antenna architecture that significantly expands the narrow Field-of-View inherent in conventional FSAs, improving sensing coverage. Additionally, we develop a sensing signal-to-noise-ratio-based signal processing framework that reliably estimates target direction in multipath-rich environments. We prototype WiRainbow and evaluate its performance through benchmark experiments and real-world case studies, demonstrating its ability to achieve accurate, robust, and cost-effective direction awareness for diverse Wi-Fi sensing applications.