Integrating Passive UHF RFID Tags with WSN Nodes: Challenges and Opportunities

Abstract

Radio Frequency Identification (RFID) and Wireless Sensor Networks (WSNs) have received an ever-increasing attention in recent years, mainly because they represent two of the most important technologies enabling the Internet of Things vision. Although designed originally with different objectives, WSN and RFID represent two complementary technologies whose integration might increase their functionalities and extend their range of applications. However, important technological issues must still be solved in order to fully exploit the potentialities offered by such integration. In this work, an innovative RFID-WSN integration approach is presented and validated. It relies on the interconnection of a new-generation, long-range, EPCglobal Class-1 Generation-2 Ultra-High-Frequency (UHF) RFID tag with a commercial WSN node via the I2C interface. Experimental results have demonstrated the effectiveness of the proposed approach compared to existing solution in the literature. Interesting application scenarios enabled by the proposed RFID-WSN integration approach are briefly summarized at the end of the paper.

A Review of RFID Sensors, the New Frontier of Internet of Things

“…The operative life of these tags is limited by the battery, which is usually not replaceable. As an example, the Monza X-2K RFID chip manufactured by Impinj Inc. (Seattle, WA, USA) [15] provides a performance boost via a 'battery-assisted passive mode' [4], when both read sensitivity (−17 dBm) and write sensitivity (−12 dBm) of the chip increase up to −24 dBm when a DC voltage is provided [4]. Figure 5 illustrates a scheme of RFID tags relying on batteryassisted sensors.…”

“…However, the flexibility offered by the WISP solution is paid for with an increased price. Battery-less configurations have recently been developed in which the microcontroller requires a few milliwatts [4]. Moreover, they offer the possibility of gathering the energy required to drive the data acquisition from the interrogation signal, as in the case of conventional passive tags.…”

“…In case of battery assisted RFID sensors or battery-assisted passive mode, or battery powered; in the latter case, they do not need a frequent change of the batteries as in the case of traditional wireless sensor nodes. In case of battery assisted RFID sensors or battery-assisted passive mode, a simple circuit is built around the memory chip, thus enabling the chip to switch to a local energy-assisted mode only when it senses a certain stimulus [4]. Instead, chip-based passive sensors acquire the power required for activation from the reader through wireless power transfer.…”