Collaborative Research: SWIFT: SMALL: Continuous-tuning matrix-beamforming MIMO enabled multi-mode injection-locking passive Wi-Fi sensing

Wi-Fi based sensing is attracting great interests for emerging applications such as vital signs monitoring, gesture recognition, through-the-wall imaging, and indoor localization. However, the state-of-the-art Wi-Fi sensing systems either require modification to the Wi-Fi access point, or do not have enough sensitivity/resolution to reliably support applications such as long-term micro-motion sensing.

Conventional single mode operation also faces challenges in the presence of multiple human subjects. To tackle these challenges, in this project, a novel multi-mode passive Wi-Fi sensing system leveraging continuous tunable matrix beamforming and multi-mode injection lock detection technologies will be developed to transform current and next generation Wi-Fi infrastructure to enable many sensing applications for smart health care, human-machine interface, localization, public safety, and smart living.

The proposed sensing system features low cost, low power, wide dynamic range, high sensitivity, continuous multiple-object tracking, and multiple-mode configuration with less computational effort. The research outcome may benefit the long-term U.S. health program and aim to make modern living and office environment smart with minimum added hardware costs and no extra spectrum resources.

On the educational side, the project will create rich impacts on education for K-12, undergraduate, and underrepresented groups. It will also cultivate entrepreneurship mindset and integrate industrial experience into students training.

This project focuses on new innovations in passive Wi-Fi sensing technology based on existing wireless infrastructure to boost its spectrum utilization efficiency. To be specific, the following innovations will be pursued: a) An advanced Nolen matrix beamforming and a group delay compensation inspired wideband methodology will be invented to support concurrent multiple target sensing across a wide Wi-Fi frequency band.

Furthermore, 3D detection will be enabled by 3D design of the proposed beamforming array. b) A phase shifter-relaxed and control relaxed circuit topology will be developed to steer the multiple beams generated by the proposed matrix network, which facilitates 3D tracking characteristic for passive Wi-Fi sensing with low power consumption, low computation load, low hardware cost, and a compact size. c) A passive injection-locked detection architecture and advanced signal processing algorithms will be invented to meet the high sensitivity and wide dynamic range requirements that challenge conventional sensing approach. Empowered by matrix beamforming, the proposed architecture and signal processing will break the boundary and enable low-power passive sensing of micro-motions. d) A passive/active switchable detection architecture is proposed to support multiple operation modes such as micro-Doppler, frequency-modulated continuous-wave (FMCW) and frequency-shift keying (FSK) detection in various application scenarios. e) 3D glass technology, antenna-in-package (AiP), and flexible wearable tags will be developed to integrate a passive Wi-Fi system platform with compact size, low cost, and high performance.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.