The Research On Multiple Tags Anti-collision Algorithm Of The Radio Frequency Identification Technique

Radio Frequency Identification is a kind of auto-identification technology rising in the 1990s,it has been applied widely in many fields such as Industrial Automation,Commercial Automation and Transport Control. Anti-collision is significant to these applications. Taking into account of the particularities of the radio frequency identification system, TDMA is the methods often used to deal with the collision problem.The ALOHA-based anti-collision algorithms belong to the stochastic collision resolution. In these algorithms, tags can only transmit their data packets in their unique slots distributed by the reader. This kind of algorithm is easy to be implemented, they are often applied in the HF (High Frequency) systems in which the number of tags to be identified is not large. An improved tag anti-collision algorithm based on framed slotted ALOHA algorithm is proposed. It assumes that a reader performs tag identification processes repeatedly for object tracking and monitoring applications. In order to reduce collisions and identify tags promptly, we use information obtained from the last process of tag identification at a reader. The emulation experiment shows that this algorithm causes fewer collisions and takes shorter delay for recognizing all tags, it will have great application prospect.Binary tree-based anti-collision algorithms belong to the deterministic collision resolution. In this kind of algorithms, tags, which transmit at the same time, form a set. When a set causes collision, the mechanisms split it into two subsets just like a binary tree and attempt to recognize two subsets in turn. With this method, we can recognize the tags more accurately, and it is often applied into the UHF (Ultra High Frequency) systems. An improved tag anti-collision algorithm based on query tree algorithm is proposed. It assumes that a reader performs tag identification processes repeatedly for object tracking and monitoring applications, the information obtained from current identification round is stored into a queue, and we can use the information directly in the next identification round to obtain shorter delay. This algorithm also considers about tags movements. The emulation experiment shows its advantages.