Abstract :
In this paper, we propose a hybrid query tree protocol that combines a tree based query protocol with a slotted backoff mechanism. The proposed protocol decreases the average identification delay by reducing collisions and idle time. To reduce collisions, we use a 4-ary query tree instead of a binary query tree. To reduce idle time, we introduce a slotted backoff mechanism to reduce the number of unnecessary query commands. For static scenarios of tags, we extended the proposed protocol by adopting two phases. First, in leaf query phase for existing tags, the interrogator queries leaf-nodes directly to reuse query strings in the previous session. Second, in root query phase for new arriving tags, the interrogator starts the query process from the roof-node. Simulation reveals that the proposed protocol achieves lower identification delay than existing tag collision arbitration protocols regardless of whether tags are mobile or not.
Keywords :
protocols; radiofrequency identification; trees (mathematics); 4-ary query tree; RFID systems; average identification delay; binary query tree; hybrid query tree protocol; interrogator queries leaf-nodes; leaf query phase; reuse query strings; root query phase; slotted backoff mechanism; tag collision arbitration; Communications Society; Computer science; Costs; Delay effects; Intrusion detection; Passive RFID tags; Protocols; Query processing; RFID tags; Radiofrequency identification;