6lo-RFID: A Framework for Full Integration of Smart UHF RFID Tags into the Internet of Things

Recent technological advancements have transformed UHF passive RFID tags into "smart" transponders enhanced with computational and sensing capabilities, thus legitimated to become fully-fledged components of the IoT. Nonetheless, RFID technology has not been addressed yet by the IETF 6lo working group among the various link layer technologies for running IPv6 over networks of resource-constrained nodes in the IoT. Research works in the scientific literature only consider proxy-based solutions for RFID inclusion in the IoT and do not suggest any ultimate approach to enable interoperability at the network and application layers. This article fills the gap by designing and testing a unified IPv6-based framework to access and manipulate RFID tags' resources by means of the standard CoAP. To this purpose, an adaptation layer, named 6lo-RFID, is specifically designed to run IPv6 over the RFID link technology. Key design aspects are addressed, such as the 6lo-RFID frame format and exchange, IPv6 header compression, fragmentation, network addressing and communication on the air interface. The designed solution is also compliant with the EPCglobal Class-1 Generation-2 standard for RFID. In addition, we manufactured a smart UHF RFID tag platform to demonstrate the full-IPv6 protocol stack and assess its performance for bidirectional real-time communications over the RFID radio interface.