A Progressive Population Estimation Based Binary Query Tree Protocol for Efficient RFID Tag Collision Resolution

RFID technology enables the automatic identification of physical items and acts as a bridge between the physical world and the cyber space. But tag collision remains a key challenge that affects the universal deployment of the RFID system. For the efficient resolution of collisions caused by passive memory-less RFID tags, this paper proposes the progressive estimation of tag population and an enhanced binary query tree protocol. In this protocol, after an idle or a successful query, according to the number of tag already identified and the binary query string broadcasted by the reader, the overall population of tags near the reader is estimated, and the optimal binary string for the reader to broadcast in the next query will be calculated. This process is performed repeatedly until all collisions are resolved. Theoretical analysis and numeric simulation are performed, it is verified that this protocol performs better in terms of throughput, message complexity and time latency.