Beam-switched circular array reduces Wi-Fi angle ambiguity
A Beam-Switched Sparse Circular Array for Passive Wi-Fi Sensing
Information Theory
Summary
Wi-Fi devices can sometimes struggle to tell exactly where a signal is coming from around them because of technical limits in how their antennas are arranged. The authors looked at a special kind of antenna layout called a uniform circular array, which can help solve this, but when only a few antennas are used, this setup can cause confusing signals called grating lobes. They developed a method to switch antenna beams in a staggered way that reduces these confusing signals without needing extra hardware. This helps make Wi-Fi sensing more accurate when figuring out the direction signals arrive from all around.
What this means in practice
- •For wireless device engineers: Improve Wi-Fi devices’ ability to track user movement by reducing angle measurement errors with beam-switched circular antennas.$Commercial implications: Enables more accurate passive Wi-Fi sensing products for consumer electronics and smart home devices using only four RF chains.
- •For indoor localization teams: Create more reliable 360-degree indoor positioning systems by mitigating ambiguities in angle estimations from sparse antenna arrays.
Authors
Yang Chen, Riccardo Bersan, Daniele Piazza, Stefano Savazzi, Michele D'Amico
Abstract
Wi-Fi sensing applications require unambiguous angle-of-arrival (AoA) estimation over the full azimuth plane. Uniform circular arrays (UCAs) are shown to remove this ambiguity, but deploying the four RF chains typically available on commercial Wi-Fi chipsets into a sparse layout suffers from spatial undersampling. Such undersampling produces strong grating lobes. To overcome this hardware bottleneck, we first establish a generalized array manifold incorporating element radiation patterns, revealing the suitability and degradation mechanisms of directional UCAs. Then we propose an angularly staggered beam-switched UCA architecture that leverages the spatial complementarity. Numerical evaluations demonstrate that the proposed scheme effectively mitigates grating-lobe ambiguities without increasing the number of RF chains, significantly reducing AoA estimation outliers and improving omnidirectional tracking performance.