Passive UHF-RFID Localization Based on the Similarity Measurement of Virtual Reference Tags

With the appearance of the new concepts "smarter planet," "industry 4.0" and "self-service supermarket," radio frequency identification (RFID), a key technology of Internet of Things, has been a hot research topic in recent years. Owing to the long read range, fast read speed and low cost, RFID in the ultrahigh frequency using passive tags has achieved great development in the management and tracking of asset and warehousing, personnel location, and robot navigation. In the meantime, there is a growing demand for the accurate localization indoors. In this paper, a method of similarity measurement of virtual reference tags using phase and receive signal strength indicator (RSSI) is designed to estimate the position of tags. The attributes of virtual reference tags, such as phase and RSSI, are calculated by the natural neighbor interpolation. Moreover, the Laiyite criterion with variable coefficient is presented to remove the multipath error. A 2-D platform is deployed to test the validity of the method. Compared with a k-nearest neighbor and multilayer perceptron, similarity measurement of virtual reference tags has a better performance for localization, which can meet the demand of the practical application.