PDF(Pubmed)
Abstract：
To provide diverse in-home services like elderly care, versatile activity recognition technology is essential. Radio-based methods, including WiFi CSI, RFID, and backscatter communication, are preferred due to their minimal privacy intrusion, reduced physical burden, and low maintenance costs. However, these methods face challenges, including environmental dependence, proximity limitations between the device and the user, and untested accuracy amidst various radio obstacles such as furniture, appliances, walls, and other radio waves. In this paper, we propose a frequency-shift backscatter tag-based in-home activity recognition method and test its feasibility in a near-real residential setting. Consisting of simple components such as antennas and switches, these tags facilitate ultra-low power consumption and demonstrate robustness against environmental noise because a context corresponding to a tag can be obtained by only observing frequency shifts. We implemented a sensing system consisting of SD-WiFi, a software-defined WiFi AP, and physical switches on backscatter tags tailored for detecting the movements of daily objects. Our experiments demonstrate that frequency shifts by tags can be detected within a 2 m range with 72% accuracy under the line of sight (LoS) conditions and achieve a 96.0% accuracy (F-score) in recognizing seven typical daily living activities with an appropriate receiver/transmitter layout. Furthermore, in an additional experiment, we confirmed that increasing the number of overlaying packets enables frequency shift-detection even without LoS at distances of 3-5 m.
摘要：
为了提供不同的家庭服务，例如老年人护理，多才多艺的活动识别技术是必不可少的。基于无线电的方法，包括WiFiCSI,RFID,和反向散射通信，是首选，因为他们最小的隐私入侵，减轻身体负担，和低维护成本。然而,这些方法面临挑战，包括环境依赖，设备和用户之间的接近限制，在各种无线电障碍如家具中未经测试的准确性，电器，墙壁,和其他无线电波。在本文中,我们提出了一种基于频移反向散射标签的家庭活动识别方法，并在接近真实的住宅环境中测试了其可行性。由天线和开关等简单组件组成，这些标签有助于超低功耗，并表现出对环境噪声的鲁棒性，因为仅通过观察频移就可以获得与标签相对应的上下文。我们实现了一个由SD-WiFi组成的传感系统，软件定义的WiFiAP，以及为检测日常物体的运动而定制的反向散射标签上的物理开关。我们的实验表明，在视线（LoS）条件下，可以在2m范围内以72％的精度检测到标签的频移，并在识别七个典型的日常生活活动时实现96.0％的精度（F得分）适当的接收器/发射器布局。此外，在一个额外的实验中，我们证实，即使在3-5m的距离没有LoS的情况下，增加重叠数据包的数量也可以实现频移检测。
