Collision-Resilient Multi-State Query Tree Protocol for Fast RFID Tag Identification

RFID (radio frequency identification) is a RF based identification system, where RF reader reads (and writes) data from each entity (RF tag). Upon request from reader, tags in reader´s accessible RF range will respond, and if the number of tags is larger than 2, the reader cannot identify tags (collision). To avoid the collision, there are two previous approaches: ALOHA based and binary tree algorithm. However, they are essentially collision avoidance algorithms, and require much overhead in retransmission time. In this paper, we present collision recovery scheme for RFID system. It uses 20 symbols, and each symbol is 16-bit vectors derived from (16, 4, 1)-BIBD (balanced incomplete block design) which is resilient to collision. Although our scheme can decrease the total number of support users, it shows good performance even with low SNR region