451 research outputs found
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 âGen 2â 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 EducaciĂłn 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 readerâs 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
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Leveraging Backscatter for Ultra-low Power Wireless Sensing Systems
The past few years have seen a dramatic growth in wireless sensing systems, with millions of wirelessly connected sensors becoming first-class citizens of the Internet. The number of wireless sensing devices is expected to surpass 6.75 billion by 2017, more than the world\u27s population as well as the combined market of smartphones, tablets, and PCs. However, its growth faces two pressing challenges: battery energy density and wireless radio power consumption. Battery energy density looms as a fundamental limiting factor due to slow improvements over the past several decades (3x over 22 years). Wireless radio power consumption is another key challenge because high-speed wireless communication is often far more expensive energy-wise than computation, storage and sensing. To make matters worse, wireless sensing devices are generating an increasing amount of data. These challenges raise a fundamental question --- how should we power and communicate with wireless sensing devices. More specifically, instead of using batteries, can we leverage other energy sources to reduce, if not eliminate, the dependence on batteries? Similarly, instead of optimizing existing wireless radios, can we fundamentally change how radios transmit wireless signals to achieve lower power consumption? A promising technique to address these questions is backscatter --- a primitive that enables RF energy harvesting and ultra-low-power wireless communication. Backscatter has the potential to reduce dependence on batteries because it can obtain energy by rectifying the wireless signals transmitted by a backscatter reader. Backscatter can also work by reflecting existing wireless signals (WiFi, BLE) when these are available nearby. Because signal reflection only consumes uWs of power, backscatter can enable ultra-low-power wireless communication. However, the use of backscatter for communicating with wireless sensing devices presents several challenges. First, decreasing RF power across distance limits the operational range of micro-powered backscatter devices. This raises the question of how to maintain a communication link with a backscatter device despite tiny amount of harvested power. Second, even though the backscatter RF front-end is extremely power-efficient, the computational and sensing overhead on backscatter sensors limit its ability to operate with a few micro-Watts of power. Such overhead is a negligible factor of overall power consumption for platforms where radio power consumption is high (e.g. WiFi or Bluetooth based devices). However, it becomes the bottleneck for backscatter based platforms. Third, backscatter readers are not currently deployed in existing indoor environments to provide a continuous carrier for carrying backscattered information. As a result, backscatter deployment is not yet widespread. This thesis addresses these challenges by making the following contributions. First, we design a network stack that enables continuous operation despite decreasing harvested power across distance by employing an OS abstraction --- task fragmentation. We show that such a network stack enables packet transfer even when the whole system is powered by a 3cmx3cm solar panel under natural indoor light condition. Second, we design a hardware architecture that minimizes the computational overhead of backscatter to enable over 1Mbps backscatter transmission while consuming less than 100uWs of power, a two order of magnitude improvement over the state-of-the-art. Finally, we design a system that can leverage both ambient WiFi and BLE signals for backscatter. Our empirical evaluation shows that we can backscatter 500bps data on top of a WiFi stream and 50kbps data on top of a Bluetooth stream when the backscatter device is 3m away from the commercial WiFi and Bluetooth receivers
CriptografĂa ligera en dispositivos de identificaciĂłn por radiofrecuencia- RFID
Esta tesis se centra en el estudio de la tecnologĂa de identificaciĂłn por radiofrecuencia (RFID), la cual puede ser considerada como una de las tecnologĂas mĂĄs prometedoras dentro del ĂĄrea de la computaciĂłn ubicua. La tecnologĂa RFID podrĂa ser el sustituto de los cĂłdigos de barras. Aunque la tecnologĂa RFID ofrece numerosas ventajas frente a otros sistemas de identificaciĂłn, su uso lleva asociados riesgos de seguridad, los cuales no son fĂĄciles de resolver. Los sistemas RFID pueden ser clasificados, atendiendo al coste de las etiquetas, distinguiendo principalmente entre etiquetas de alto coste y de bajo coste. Nuestra investigaciĂłn se centra fundamentalmente en estas Ășltimas. El estudio y anĂĄlisis del estado del arte nos ha permitido identificar la necesidad de desarrollar soluciones criptogrĂĄficas ligeras adecuadas para estos dispositivos limitados. El uso de soluciones criptogrĂĄficas estĂĄndar supone una aproximaciĂłn correcta desde un punto de vista puramente teĂłrico. Sin embargo, primitivas criptogrĂĄficas estĂĄndar (funciones resumen, cĂłdigo de autenticaciĂłn de mensajes, cifradores de bloque/flujo, etc.) exceden las capacidades de las etiquetas de bajo coste. Por tanto, es necesario el uso de criptografĂa ligera._______________________________________This thesis examines the security issues of Radio Frequency Identification
(RFID) technology, one of the most promising technologies in the field of
ubiquitous computing. Indeed, RFID technology may well replace barcode
technology. Although it offers many advantages over other identification
systems, there are also associated security risks that are not easy to address.
RFID systems can be classified according to tag price, with distinction
between high-cost and low-cost tags. Our research work focuses mainly
on low-cost RFID tags. An initial study and analysis of the state of the
art identifies the need for lightweight cryptographic solutions suitable for
these very constrained devices. From a purely theoretical point of view,
standard cryptographic solutions may be a correct approach. However,
standard cryptographic primitives (hash functions, message authentication
codes, block/stream ciphers, etc.) are quite demanding in terms of circuit
size, power consumption and memory size, so they make costly solutions
for low-cost RFID tags. Lightweight cryptography is therefore a pressing
need.
First, we analyze the security of the EPC Class-1 Generation-2 standard,
which is considered the universal standard for low-cost RFID tags.
Secondly, we cryptanalyze two new proposals, showing their unsuccessful
attempt to increase the security level of the specification without much further
hardware demands. Thirdly, we propose a new protocol resistant to
passive attacks and conforming to low-cost RFID tag requirements. In this
protocol, costly computations are only performed by the reader, and security
related computations in the tag are restricted to very simple operations.
The protocol is inspired in the family of Ultralightweight Mutual Authentication
Protocols (UMAP: M2AP, EMAP, LMAP) and the recently proposed
SASI protocol. The thesis also includes the first published cryptanalysis of
xi
SASI under the weakest attacker model, that is, a passive attacker. Fourthly,
we propose a new protocol resistant to both passive and active attacks and
suitable for moderate-cost RFID tags. We adapt Shieh et.âs protocol for
smart cards, taking into account the unique features of RFID systems. Finally,
because this protocol is based on the use of cryptographic primitives
and standard cryptographic primitives are not supported, we address the
design of lightweight cryptographic primitives. Specifically, we propose
a lightweight hash function (Tav-128) and a lightweight Pseudo-Random
Number Generator (LAMED and LAMED-EPC).We analyze their security
level and performance, as well as their hardware requirements and show that both could be realistically implemented, even in low-cost RFID tags
Case Study: Installing RFID Systems in Supermarkets
Radio frequency identification technology (RFID) is considered as the reference technology for wireless identification and item traceability. Supermarkets are one of those scenarios where the RFID potential can be harnessed. In theory, RFID in supermarkets shows several advantages compared with traditional barcode systems, offering realâtime inventory, stock control, cash queues, among others. In practice, its massive and global implementation is still being delayed due to the high quantity of factors that degrade the RFID system performance in these scenarios, causing uncontrolled items and identification losses and, at the end, economical losses. Some works in the scientific literature studied a single or a set of problems related to RFID performance, mostly focused on a specific communication layer: antennas and hardware design, interferences at physical layer, medium access control (MAC) protocols, security issues, or middleware challenges. However, there are no works describing in depth the set of factors affecting RFID performance in a specific scenario and contemplating the entire communication layer stack. The first challenge of this chapter is to provide a complete analysis of those physical and environmental factors, hardware and software limitations, and standard and regulation restrictions that have a direct impact on the RFID system performance in supermarkets. This analysis is addressed by communication layers, paying attention to the point of view of providers, supermarket companies, and final customers. Some of the most feasible and influential research works that address individual problems are also enumerated. Finally, taking the results extracted from this study, this chapter provides a Guide of Good Practices (GGPs), giving a global vision for addressing a successful RFID implementation project, useful for researchers, developers, and installers
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