An Indoor Multi-Tag Cooperative Localization Algorithm Based on NMDS for RFID

For radio frequency identification (RFID) system, the location information is very important in many applications, such as Internet of Things, logistics, library management, and so on. Most of traditional RFID localization algorithms can only locate one tag at a time. However, multitag localization is desired in many RFID applications. In this paper, we propose a novel range-free algorithm named nonmetric multidimensional scaling (NMDS)-RFID(F), which combines NMDS algorithm and the fingerprinting localization algorithm to achieve indoor RFID multitag cooperative localization. The NMDS-RFID(F) algorithm firstly uses received signal strength Euclidean distance based on fingerprinting method to get the rank order of the distance for all pairs of tags, and then NMDS algorithm is used to generate the relative coordinates of tags. Finally, due to the coordinates of reference tags are known, we can use the coordinate system registration algorithm to get the absolute coordinates of tags. Simulation results show that the NMDS-RFID(F) algorithm outperforms some previous RFID localization algorithms.