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

基于Wi-Fi的传感正在吸引着人们对生命体征监测、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传感系统要么需要对Wi-Fi接入点进行修改，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。在存在多个人类主体的情况下，传统的单模式操作也面临挑战。为了应对这些挑战，在该项目中，将开发一种新型的多模无源Wi-Fi传感系统，利用连续可调矩阵波束成形和多模注入锁定检测技术来改造现有和下一代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多种传感应用成为可能。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。这项研究成果可能有利于美国的长期健康计划，目标是让现代生活和办公环境变得智能，增加的硬件成本最低，不需要额外的频谱资源。在教育方面，该项目将对K-12、本科生和代表性不足群体的教育产生丰富的影响。它还将培养创业心态，并将产业经验融入学生培养。该项目专注于基于现有无线基础设施的被动Wi-Fi感知技术的新创新，以提高其频谱利用效率。具体地说，将追求以下创新：a)将发明先进的诺伦矩阵波束形成和受群延时补偿启发的宽带方法，以支持跨宽Wi-Fi频段的并发多目标检测。此外，3D检测将通过所提出的波束形成阵列的3D设计来实现。B)开发了移相器松弛和控制松弛的电路拓扑来引导由所提出的矩阵网络产生的多波束，该网络具有低功耗、低运算量、低硬件成本和紧凑的三维跟踪特性。C)将发明无源注入锁定检测结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的要求。在矩阵波束形成的支持下，所提出的体系结构和信号处理将打破边界，实现对微小运动的低功率被动感知。D)提出了一种被动/主动可切换检测体系结构，以支持多种应用场景下的微多普勒、调频连续波(FMCW)和频移键控(FSK)检测等多种工作模式。E)将开发3D玻璃技术、封装天线(AIP)和灵活的可穿戴标签，以集成尺寸紧凑、低成本和高性能的无源Wi-Fi系统平台。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.