A Novel Anti-collision Algorithm in RFID System

Abstract

Tag anti-collision is a signiflcant issue in RFID system design, which determines the identiflcation speed. Thus a novel anti-collision algorithm based on Binary Tree Searching Algorithms and BIBD (4,2,1) is proposed to resolve this problem. A tag is divided into several sections, which each contain special sequences. Readers can e-ciently get every ID by identifying each section one by one. Mathematicalanalysis and simulations results show that the algorithm presented improves the identiflcation speed and outperforms the existing ones. It especially flts the identiflcation condition which contains numerous tags or tags with long ID. Radio Frequency Identiflcation (RFID) is a contactless automatic identiflcation technology. In a RFID system, wireless RF communication techniques are used to achieve the duplex communication between the reader and tags. RFID overcomes the limitations of other automatic identiflcation applications such as bar codes, magnetic cards and IC cards. RFID has advantages for example fast identifying speed, data encryption, longevity and is not afiected by the surrounding environment. It is especially used to cooperate with other robotic equipments. In recently years RFID is one technology which developed at a rapid speed that has worldwide applications. RFID is now a third generation identiflcation technology. The RFID system mainly consists of three basic components: the tag, the reader and the host data processing system. Every tag has a global unique identiflcation code (ID). When a tag enters the reader's RF range, it is powered on by induction and sends the stored ID code or other data from its inner memory to the reader. Reader can identify all tags within the interrogation zone of its antenna via wireless RF communication technology and algorithms. Through interfaces readers can be connected to a host and the stored information from the tags can be accessed with data processing systems. Additionally, when linked with a LAN, the processed data can be transmitted over the internet and shared with other network applications. When several tags simultaneously enter into a reader's interrogation zone, they start to transmit the stored data, each tag trying to connect to the channel. As a result, the signals interfere with each other and the so-called collision happens. Resolving collisions has been a consistent research subject in wireless communication, included RFID systems. When the collision problem is solved, RFID system works efiectively. In a RFID system, there are two types of collision resolution scheme: (1) probabilistic algorithm which is based on ALOHA. (2) Deterministic algorithm which detects collided bits and splits disjoint subsets of tags. In generally, probabilistic algorithm is simpler than deterministic algorithm and is adapted in practice, but its performance would decrease sharply when the tag quantity increases. Though deterministic algorithm has complicated circuits, it has obvious advantages with its faster identiflcation speed and higher accurate rate. Especially, deterministic algorithm flts in the identiflcation environment which contains large quantity of tags or tags with long ID. In this paper a novel anti-collision deterministic algorithm is presented.