This paper introduces a highly integrated passive wireless sensing system based on extended EPC Gen2 protocol, using sensor tags and a reader to support concurrent data streams from multiple sensors. Multiple Subcarrier Multiple Access (MSMA) is used by assigning different subcarrier frequencies to the sensor tags for backscattering so that each tag has an independent channel for communication to achieve the simultaneous streaming of multi-sensor data. In order to improve the subcarrier frequency accuracy and further increase the number of communication channels, this paper proposes a novel method of subcarrier frequency calibration based on the Gen2 protocol. This method enables a high accuracy clock to be generated on-chip. At the same time, this paper also proposes a method based on Gen2 protocol to start a group of tags and receive real-time data in parallel. The tag chip is fabricated in a 0.18 μm CMOS process with a die size of 850 μm × 850 μm, and the reader prototype is built using software-defined radio equipment. The test results show that the sensing system proposed in this paper can collect and recognize concurrent data streams from multiple sensor tags synchronously. The measured sensitivity of the sensor tag is -14.9dBm with a 3-axis accelerating sensor, and the calibration accuracy of subcarrier frequency is better than ±0.385KHz in the range of 40KHz-640KHz. With this accuracy, the tags can be allocated up to 78 subcarrier communication channels theoretically.
- Sensor systems
- Tag chip
- Wireless communication
- Wireless sensor networks
- concurrent data streaming
- frequency calibration
- passive wireless sensing system.
- structural health monitoring (SHM)
ASJC Scopus subject areas
- Signal Processing
- Information Systems
- Hardware and Architecture
- Computer Science Applications
- Computer Networks and Communications