Tag anti-collision algorithms in RFID systems - a new trend

RFID is a wireless communication technology that provides automatic identification or tracking and data collection from any tagged object. Due to the shared communication channel between the reader and the tags during the identification process in RFID systems, many tags may communicate with the reader at the same time, which causes collisions. The problem of tag collision has to be addressed to have fast multiple tag identification process. There are two main approaches to the tag collision problem: ALOHA based algorithms and tree based algorithms. Although these methods reduce the collision and solve the problem to some extent, they are not fast and efficient enough in real applications. A new trend emerged recently which takes the advantages of both ALOHA and tree based approaches. This paper describes the process and performance of the tag anti-collision algorithms of the tree-ALOHA trend

Influence of Managing the Number of Tag Bits Transmitted on the Query Tree RFID Collision Resolution Protocol

Radio Frequency Identification (RFID) technology is increasingly becoming popular, for its widespread use and more sophisticated applications. The coexistence of tags sharing the communication channel requires solutions to message collisions, which degrade bandwidth, and increase the number of transmitted bits. A new methodology called ‘window’ is presented to manage the number of bits transmitted by a tag. The aim is show how the query tree (QT) protocol is influenced by this feature, and how the performance of the novel protocol, query window tree (QwT), improves when the tag ID distribution is correlated. Therefore, we have performed a fair comparison of the Query Tree and the new proposed QwT protocol for various tag ID distributions. Simulations show that the QwT positively decreases the total number of bits that are transmitted by tags

Exploiting ID Knowledge for Tag Identification in RFID Networks

In this paper, we consider the problem of identifying a set of objects in an RFID network. We propose a query tree based protocol to reduce the number of transmission collisions. The key idea of our protocol is to take advantage of the (partial) knowledge about the set of tags to be identified: in particular, their approximated number, and above all their distribution. More specifically, we show how much gain in performance can be achieved by having information about the set of IDs to be identified. Such information can be obtained from statistical data, or from other features, depending on the application. Of course, a perfect knowledge makes useless the identification process: the aim of this work is to show how query tree protocols improve, by taking into account of the information about the tags. Simulation results show that our approach performs better than classical query tree protocols [1], in terms of number of queries needed to identify all tags, which is a commonly used metric, strictly related to delay. Moreover, our approach outperforms also Aloha-based protocols that for their randomized nature, are independent from the IDs distributions: in such protocols, tags randomly choose a slot in which transmit, that is equivalent to "re-naming" the IDs, so they do not take any advantage from the knowledge of the original ID distribution