Breath monitoring helps assess the general personal health and gives clues to chronic diseases. Yet, current breath monitoring technologies are inconvenient and intrusive. For instance, typical breath monitoring devices need to attach nasal probes or chest bands to users. Wireless sensing technologies have been applied to monitor breathing using radio waves without physical contact. Those wireless sensing technologies however require customized radios which are not readily available. More importantly, due to interference, such technologies do not work well with multiple users. When multiple users are present, the detection accuracy of existing systems decreases dramatically. In this paper, we propose to monitor users’ breathing using commercial-off-the-shelf (COTS) RFID systems. In our system, passive lightweight RFID tags are attached to users’ clothes and backscatter radio waves, and commodity RFID readers report low level data (e.g., phase values). We reliably detect the effective human respiration corresponded signal and track periodic body movement due to inhaling and exhaling by analyzing the low level data reported by commodity readers. To enhance the measurement robustness, we synthesize data streams from an array of multiple tags to improve the monitoring accuracy. Our design follows the standard EPC protocol which arbitrates collisions in the presence of multiple tags. We implement a prototype for the breath monitoring system with commodity RFID systems. The experiment results show that the prototype system can simultaneously monitor breathing with high accuracy even with the presence of multiple users.

中文翻译：

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TagBreathe：使用商品 RFID 系统监控呼吸

呼吸监测有助于评估一般个人健康状况，并为慢性病提供线索。然而，当前的呼吸监测技术不方便且具有侵入性。例如，典型的呼吸监测设备需要将鼻探头或胸带连接到用户身上。无线传感技术已应用于使用无线电波监测呼吸，无需身体接触。然而，那些无线传感技术需要定制的无线电，而这些无线电并不容易获得。更重要的是，由于干扰，这种技术不能很好地用于多个用户。当存在多个用户时，现有系统的检测精度会急剧下降。在本文中，我们建议使用商用现货 (COTS) RFID 系统来监控用户的呼吸。在我们的系统中，无源轻量 RFID 标签贴在用户的衣服和反向散射无线电波上，商品 RFID 阅读器报告低级数据（例如，相位值）。我们通过分析商品阅读器报告的低级数据，可靠地检测到有效的人体呼吸对应信号并跟踪由于吸气和呼气引起的周期性身体运动。为了增强测量的鲁棒性，我们从多个标签的阵列中合成数据流，以提高监测精度。我们的设计遵循标准 EPC 协议，该协议在多个标签存在的情况下仲裁冲突。我们使用商品 RFID 系统实现了呼吸监测系统的原型。实验结果表明，即使有多个用户存在，原型系统也可以同时高精度地监测呼吸。