Occupancy Monitoring Using Batteryless RFID Motion Sensor Tags

This paper presents a batteryless radio frequency identification motion sensor tag that integrates a passive infrared sensor, a radio frequency energy harvesting front end, and real-time digital signal processing involving two algorithms, enabling reliable occupancy detection without batteries, continuous power, and infrastructure modification. In addition, the fully batteryless sensor tag incorporates an event-capture memory circuit designed to preserve occupancy information during power interruptions. Two real-time algorithms filter sensor noise and reduce power consumption of the tag to increase its read range. Experimental results show 3.5m motion detection range from the sensor, and reliable tag operation at reader distances up to 2.8m under standard ultra high frequency conditions. The occupancy detection accuracy of the proposed system improves from 88.05% to 97.99% after applying digital signal processing, which is among the highest reported compared to state-of-the-art occupancy detection systems. The system achieves sub-50ms update latency with an average power consumption of only 160 μW while operating fully batteryless, making the proposed tag suitable for scalable occupancy monitoring in smart building heating, ventilation, and air conditioning systems.