The Research On Anti-collision Algorithm Of Radio Frequency Identification (RFID) System

RFID (Radio Frequency Identification), an advanced technique of automatic identification and data capture, is reckoned one of the ten significant technologies of the 21st century ans has wide application prospects in production, product distribution and public safety. With the improvement of technological reliability and appliability, RFID has come to be an indispensible technological instrument for boostering management in logistics and supply chain, reducing production cost, promoting informationalization of public safety management and boltering international competitiveness. However, RFID as a rising technology is still defective.e.g. Relatively low accuracy identification and slow standardization progress. Relatively low effeciency in tag identification by reason of tag collision and reader collision is among bottlenecks of RFID. Therefore, a study for working out a quick, safe, accurate and less power-consuming solution of the collision problem has become a weighty task and has a crucial effect on the development of RFID.The thesis firstly introduces the basic structure, rationale, features, key techniques and related basic theoretical knowledge of the RFID system, secondly gives an overview and in-depth analysis especially for the tag collision and reader collision in wireless data transmission. Multiple access protocols is expected to be applied within the reader range in the RFID system so as to solve the collision problem recurred by simultaneous data transmission of several tags to the reader. In light of their limitations in design complexity, cost, employed ways etc, space division multiple, frequency division multiple and code division multiple are unsuitable for solving the collision problem of the RFID system. This thesis conducts an analysis on the ALOHA and binary tree algorithm of the time division multiple and their improved algorithms and points out their merits and demerits.By combining the merits of the ALOHA and binary tree algorithms, this thesis proposes the notion of combined frame and develops new combined frame algorithm and new time-slot controlled combined frame algorithm. The performance analysis and the simulation of the two algorithms indicate that the two algorithms can double the throughput by the ALOHA. By effectively making advantage of the features of collided time-slot combined frame algorithm and dynamic binary tree algorithm, the combined frame algorithm boosts the utilization rate of time-slots between frames and the utilization rate of signal channels in reading the tags by 63%, diminishing the reading time and enhancing the identification efficiency. Time-slot controlled combined frame algorithm is the result of further adjustment of collided time-slot based on the combined frame algorithm. Though slightly affecting the reading efficiency, time-slot controlled combined frame algorithm can still bolster reading efficiency by over 49% in comparison with the DFSA. Moreover, it decreases the time slot and the difficulty in reading tags in extremely bad conditions and therefore lowers the complexity of the algorithm.