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

基于Wi-Fi的传感技术正在吸引诸如生命体征监测、手势识别、穿墙成像和室内定位等新兴应用的极大兴趣。然而，最先进的Wi-Fi传感系统要么需要修改Wi-Fi接入点，要么没有足够的灵敏度/分辨率来可靠地支持长期微运动传感等应用。传统的单模操作也面临着多受试者存在的挑战。为了应对这些挑战，本项目将开发一种新型多模无源Wi-Fi传感系统，利用连续可调矩阵波束成形和多模注入锁检测技术，改造当前和下一代Wi-Fi基础设施，使智能医疗、人机界面、本地化、公共安全和智能生活等领域的许多传感应用成为可能。该传感系统具有低成本、低功耗、宽动态范围、高灵敏度、连续多目标跟踪和计算量少的多模式配置等特点。该研究结果可能有利于美国的长期健康计划，旨在以最小的硬件成本和额外的频谱资源，使现代生活和办公环境智能化。在教育方面，该项目将对K-12、本科和代表性不足的群体的教育产生丰富的影响。它还将培养创业思维，并将行业经验融入学生的培训中。该项目侧重于基于现有无线基础设施的无源Wi-Fi传感技术的新创新，以提高其频谱利用效率。具体而言，将追求以下创新：a)将发明一种先进的诺伦矩阵波束形成和一种受组延迟补偿启发的宽带方法，以支持跨宽Wi-Fi频段的并发多目标传感。此外，所提出的波束形成阵列的三维设计将使三维检测成为可能。b)将开发一种移相器放松和控制放松电路拓扑来引导所提出的矩阵网络产生的多波束，这有利于无源Wi-Fi传感的3D跟踪特性，具有低功耗、低计算负载、低硬件成本和紧凑的尺寸。c)将发明被动注入锁定检测架构和先进的信号处理算法，以满足挑战传统传感方法的高灵敏度和宽动态范围要求。在矩阵波束形成的支持下，所提出的架构和信号处理将打破边界，实现微运动的低功耗被动感知。d)提出无源/有源可切换检测架构，支持微多普勒、调频连续波（FMCW）、移频键控（FSK）等多种工作模式在各种应用场景下的检测。e)将开发3D玻璃技术、封装天线（AiP）和柔性可穿戴标签，以集成一个小尺寸、低成本和高性能的无源Wi-Fi系统平台。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.