Mobile RFID tag reading with non-overlapping tandem readers on a conveyor belt

Abstract

Mobile RFID tag reading on conveyor belt represents a practical scenario used widely in the supply chain industry. Typically, in RFID tag reading MAC protocols, the time the protocol takes to complete the reading of all the tags is directly proportional to the number of tags. As a natural scalability problem, when the number of mobile tags is large, the protocol that is initiated and coordinated by a reader will not be able to read all the tags, as the tags move away from the reader’s range. In this paper, we tackle this problem, by showing how a large number of tags moving on a conveyor belt can be read using a tandem of communicating readers placed along the axis of the conveyor belt. The tags that are unread by a reader could be read by the reader next in the sequence. Rather than restarting the protocol at the next reader in the sequence to read the unread tags, it can use the information from the previous reader (we call it information sharing) to improve protocol performance and hence reduce the reading time. Thanks to the advanced RFID technologies offering enhanced tag persistent times. The tags can now preserve their states in ‘power-off’ conditions for significantly longer distances in the conveyor-belt.We show that this information sharing significantly enhances the tag reading performance (in terms of number of tag reads) as compared with the traditional tag reading protocols. In our experiments, we consider the tandem reader arrangement with information sharing for ALOHA, Tree, and two different combinations of ALOHA and Tree (a.k.a. hybrid) protocols. Our performance evaluation study corroborated with extensive simulation results show that the aforementioned protocols augmented with our novel information sharing frameworks outperform their respective primitive ‘as-is’ version counterparts.