An effective frame breaking policy for dynamic framed slotted aloha in RFID

The tag collision problem is considered as one of the critical issues in RFID system. To further improve the identification efficiency of an UHF RFID system, a frame breaking policy is proposed with dynamic framed slotted aloha algorithm. Specifically, the reader makes effective use of idle, successful, and collision statistics during the early observation phase to recursively determine the optimal frame size. Then the collided tags in each slot will be resolved by individual frames. Simulation results show that the proposed algorithm achieves a better identification performance compared with the existing Aloha-based algorithms

Perfect tag identification protocol in RFID networks

Radio Frequency IDentification (RFID) systems are becoming more and more popular in the field of ubiquitous computing, in particular for objects identification. An RFID system is composed by one or more readers and a number of tags. One of the main issues in an RFID network is the fast and reliable identification of all tags in the reader range. The reader issues some queries, and tags properly answer. Then, the reader must identify the tags from such answers. This is crucial for most applications. Since the transmission medium is shared, the typical problem to be faced is a MAC-like one, i.e. to avoid or limit the number of tags transmission collisions. We propose a protocol which, under some assumptions about transmission techniques, always achieves a 100% perfomance. It is based on a proper recursive splitting of the concurrent tags sets, until all tags have been identified. The other approaches present in literature have performances of about 42% in the average at most. The counterpart is a more sophisticated hardware to be deployed in the manufacture of low cost tags.Comment: 12 pages, 1 figur

Performance evaluation of non-persistent CSMA as anti-collision protocol for active RFID tags.

In this paper we propose the use of non-persistent CSMA as an anti-collision procedure for RFID active tags. Current proposals for both passive and active tags are based on the framed slotted ALOHA protocol, which does not scale well requiring additional procedures for frame length adaptation. However, active RFID devices already include carrier sense capabilities with no additional cost and, thus, CSMA may be employed seamlessly. Nevertheless, selecting the contention micro-slots of CSMA in the classical way (i.e., with a uniform distribution and an exponential back-off algorithm) does not result in an efficient identification process, as we will demonstrate. Fortunately, better choices can be found. Recently, an optimal distribution for the selection of micro-slots for event-driven sensor networks has been computed, as well as a practical implementation: the Sift distribution. In this work we propose the application of the quasi-optimal Sift distribution along with CSMA for active tag identification. By means of an analytical study, we evaluate the average time needed for identification with this mechanism and compare it with the current ISO 18000-7 and EPC “Gen 2” standard. The results reveal that the Sift-based non-persistent CSMA outperforms both of them. Moreover, it also scales much better, without the need for further adaptation mechanismsThis work has been funded by the Spanish Ministerio de Educación y Ciencia with the projects DEP2006-56158-C03-03/EQUI and m:ciudad (FIT-330503- 2006-2, partially funded by ERDF) and by the Spanish Research Council with the ARPaq project (TEC2004-05622-C04-02/TCM)

Performance Analysis of Effective Range and Orientation of UHF Passive RFID

The purpose of this research is to characterize the performance of UHF passive RFID tags. Factors of importance are the impact of tag orientation and distance from the RFID reader. Within this study, a comprehensive literature review of RFID technology is presented as well as the methodology used for the research. Furthermore, an analysis of RFID tag experiments is discussed and the results reviewed. To accomplish this task, two main objectives have been established as goals for the study. The first objective is to determine an optimum tag orientation within the RFID reader’s normal read range. Once the optimum tag orientation is determined, the orientation is used to perform range variation tests. The end goal of these tests is to find the maximum range at which the tags are readable under normal conditions using standard equipment. Grasping an idea of RFID tag boundaries contributes to the security and privacy of the technology. This is extremely important as RFID tags are becoming the logistical tool of choice for Department of Defense (DoD) supply chains. This fundamental study creates a foundation that may support both offensive and defensive oriented research. By understanding tag weaknesses and strengths, users of the technology can make sound decisions that lead to the protection of valuable information and assets

An Efficient Prefix-Tree Algorithm for Recognizing Pre-Registered RFIDs

[[abstract]]In the past, it was necessary to scan products one by one to record information about usage or the number of items in stock. Now, to reduce the scanning time, we want to recognize multiple products with only one scan. To this end, we implement a wireless technique called radio frequency identification (RFID), which allows multi-access. Our objective is twofold. First, we must ensure that the system can recognize every product without loss of information. Second, we need to improve the recognition (scanning) speed. In this thesis, we take Easy Card (issued by Taipei Smart Card Corporation) as an example of RFID, where the reader takes 0.4 seconds to scan a card. Information would lost if the card is moved over the reader in less than 0.4 seconds, so we have to reduce the time required for recognition. We follow the 900MHz Class 0 Protocol Standard of Electronic Product Code (EPC), which implements a binary tree algorithm for anti-collision to prevent information loss. The system has to read an ID code completely (as a string of binary digits) to ensure recognition. Without changing whole architecture of the standard protocol, we modify the algorithm, which interacts with the reader and the tag. To speed up the recognition time, we improve the binary tree to prefix-tree. First, the process pre-registers the tags which need to be recognized to build a prefix-tree. Second, when the tags need to be recognized, we operate the prefix-tree for recognition. Our approach does not need to read the whole ID code. It only receives bits of the code that we need, and then the reader can get the IDs of the tags.

Survey on Lightweight Primitives and Protocols for RFID in Wireless Sensor Networks

The use of radio frequency identification (RFID) technologies is becoming widespread in all kind of wireless network-based applications. As expected, applications based on sensor networks, ad-hoc or mobile ad hoc networks (MANETs) can be highly benefited from the adoption of RFID solutions. There is a strong need to employ lightweight cryptographic primitives for many security applications because of the tight cost and constrained resource requirement of sensor based networks. This paper mainly focuses on the security analysis of lightweight protocols and algorithms proposed for the security of RFID systems. A large number of research solutions have been proposed to implement lightweight cryptographic primitives and protocols in sensor and RFID integration based resource constraint networks. In this work, an overview of the currently discussed lightweight primitives and their attributes has been done. These primitives and protocols have been compared based on gate equivalents (GEs), power, technology, strengths, weaknesses and attacks. Further, an integration of primitives and protocols is compared with the possibilities of their applications in practical scenarios