Pinpointing Anomaly RFID Tags: Situation and Opportunities

RFID is one of the most important automatic identification techniques in the future IoT world. Compared with the other techniques, RFID has various advantages such as no requirement of line of sight, the capability of wireless communication, low cost, small size, and so on. This article discusses two types of anomaly tags, i.e., missing tags and unknown tags, which usually appear due to theft or product misplacement. Generally, there are two categories of anomaly tag pinpointing protocols: boolean detection, which aims at probabilistically determining whether there exist anomaly tags or not; and exact identification, which aims at identifying all anomaly tag IDs. This article first conducts a comprehensive survey of the existing anomaly tag pinpointing protocols, particularly emphasizing their evolution road. After that, we also conduct a taxonomy of the existing protocols and summarize their pros and cons. Finally, we discuss some technical challenges and problems that have not been covered yet, and point out the potential opportunities in RFID research and applications.