Unknown Tag Identification Protocol Based on Collision Slot Resolution in Large-Scale and Battery-Less RFID System

Radio frequency identification (RFID) technology is widely used in warehouse management and supply chain management. In the actual application, unknown tags, such as newly added or incorrectly placed products, will be placed into a certain area of the warehouse. Existing identification protocols can identify such unknown tags by collecting tag IDs and comparing them with backend server. Alternatively, the known tags can be filtered through the filter vector to prevent interference from unknown tags and improve identification efficiency. However, there is a lack of consideration of the collision impact on identification efficiency. In this article, we introduce the bit tracking technology to accelerate the identification process and propose a bit-tracking-based strategy for unknown tag identification (BTUTI) protocol. We solve the problem by means of known tag deactivation and unknown tag identify. First, by adopting bit tracking technology, the reader can easily locate the positions of the collision bit. By hashing the tags of these collision slots, the collision slots can be turned into resolvable slots, thus improving the utilization rate of slots. Second, in the expected nonempty slot, the reader can send command to deactivate the known tag and skip empty slots and irresolvable collision slots. The experiment proves that BTUTI can increase the time efficiency compared to the state of the art.