Passive UHF-RFID Technology: Integrated Communication, Localization and Sensing

This paper presents an environmental mapping system based on passive Internet of Things (IoT) nodes implemented through Ultra High-Frequency (UHF) Radio Frequency IDentification (RFID) devices with sensing capabilities. An RFID sensor tag provides environmental information as temperature, humidity, lighting, etc. aside its unique identifier. The paper focuses on creating a detailed map of indoor facilities like buildings, warehouses, or plants by combining location information with sensing data. To achieve accurate positioning with passive RFID devices, the paper employs techniques based on the Synthetic Aperture Radar (SAR) method. This method utilizes the phase of the backscattering signal and the relative motion between the reading antenna and the targeted devices, which can be implemented by a mobile robot. The paper includes a demonstrator that showcases the aforementioned system. Passive RFID sensor tags capable of monitoring temperature are deployed in an indoor scenario, whereas a moving antenna implements the SAR method. The results demonstrate localization errors within a few centimeters. The paper also presents criteria for selecting trajectories that may improve localization accuracy. Furthermore, the paper evaluates the actual capabilities of commercial passive RFID sensors.