Dynamic Grouping in RFID Systems

Radio Frequency Identification (RFID) technology brings a revolutionary change in warehouse management by automatically monitoring and tracking products. The grouping problem is to efficiently inform all tags which groups they belong to, such that tags in the same group have the same group ID. With this information, the reader can transmit data through efficient multicast rather than tedious unicast. However in the dynamic RFID system, where the group IDs change frequently, existing works suffer from low time- efficiency. In light of this, this paper proposes the binary grouping (BIG) protocol to improve the grouping performance in the dynamic RFID system. BIG follows three design principles. First, for the to-be-grouped tags, BIG separates them from the entire tag set before grouping, so that the not-to-be-grouped tags will not participate in the following grouping, reducing the running delay. Second, for the update of group ID, BIG flips only the bits of group ID which differ from the previous ones, instead of updating all bits of the group ID, saving the communication overhead. Third, BIG adopts a Huffman coding based grouping scheme, which classifies tags into different groups in an efficient way. The extensive simulations show BIG outperforms the existing promising works.