Experimental investigation on tags placement affecting the efficient encoding of multiple passive UHF RFID tags with unique identifiers

Recently, the Internet of things (IoT) has emerged as a promising solution for several industrial applications. One of the key components in IoT is passive radio frequency identification (RFID) tags which do not require a power source for operations. Specifically, ultra-high frequency (UHF) tags are studied in this paper. However, due to factors such as tag-to-tag interference and inaccurate localization, RFID tags that are closely spaced together are difficult to detect and program accurately with unique identifiers. This paper investigates several factors that affect the ability to encode a specific tag with unique information in the presence of other tags, such as reader power level, tag-to-antenna distance, tag-to-tag distance and tag orientation. ANOVA results report reader power level and tag spacing, along with effect interactions power level∗tag space and tag space∗tag orientation to be significant at the levels investigated. Results further suggest a preliminary minimum tag-to-tag spacing which enables the maximum number of tagged items to be uniquely encoded without interference. This finding can significantly speed up the process of field programming in item-level tagging.