Research On Rfid Anti-Collision Algorithm Based On Capture Effect

With the rapid development of Internet and information technology, radio frequency identification (RFID) got great attention from the academic and industrial circles because it can realize the recognition and tracking of multiple objects in the far distance and has been successfully applied to various fields of logistics, retail and transportation etc.In the RFID system, it can cause tag collision if there are two or more than two tags in response to readers’request simultaneously that brings about a waste of bandwidth and increase in the total delay. Tag anti-collision is a key technology in the RFID system, but there are few algorithms that properly consider the function of capture effect on the tag identification. Based on the analysis of the impact of capture effect on the ALOHA and query tree anti-collision algorithms, further studies are as following:(1) Through analysis of the occurrence of capture effect in the RFID system’s working environment, the average tag captured probability model is constructed. It can determine the possibility of model tags’captured according to their distribution, and got the exception of slots that with the tag captured in a frame by the possibility. And the algorithm of Dynamic Framed Slotted ALOHA with Capture Effect (CE-DFSA) is proposed, which can achieve optimal capture ratio by set system’s capture ratio threshold in order to improve the system’s throughput. And the effectiveness of the algorithm was verified by experiment.(2) To avoid the problem that data would be lost in query tree process influenced with the capture effect existed, a query tree algorithm with capture effect (CE-QT) is proposed to control the range of the tag IDs’selection. It can solve the above problem through controlling the range of the tag IDs’selection, and also reduced the number of required query frequency that identify all tags in the process, at last the performance of the system is improved.(3) Aided to the problem of the low efficiency of existed GQT (Generalized Query Tree) algorithm, the hybrid query tree algorithm BCS-GQT (Generalized Query Tree with Bit Change Sensing) based on bit change sensing unit (BCS-GQT) is proposed to reduce the number of tag collision and improve the efficiency of recognition through sending tag’s continuous bit information to expand the query prefix rapidly. Finally, the simulation experiment compares the proposed algorithm BCS-GQT and CE-QT with existed algorithm GQT in the performance for the number of query frequency identified all tags and analyses the impact of the capture effect on query frequency. The result shows that validation of the BCS-GQT and CE-QT is superior to GQT.