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IEEE SSD International Multi-Conference on Systems, Signals and Devices

作者： Stefan Pfeiffer Sebastian Unger Dirk Timmermann Andreas Lehmann Institute of Applied Microelectronics and Computer Engineering University of Rostock Germany Institute of Computer Science University of Rostock Germany

ISBN: (纸本)9781467315906

Usually, safety and robustness are considered as the most important issues when designing and developing smart and wireless eHealth systems for ambient support of patients and physicians. However, information security is an indispensable design criterion due to the sensitive and critical nature of aggregated information from eHealth applications. Therefore, preventing undesired information leaks and illegal information flows is crucial for designing smart mHealth and mobile medical assistant systems. Due to the rapidly increasing complexity of these systems, finding information flow violations manually is nearly impossible. That is why there is a need for formally-based and tool supported verification methods of security properties.

关键词： Security Unified modeling language Medical services Databases Mobile handsets Semantics Mathematical model

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Evaluation of hybrid distributed least squares for improved localization via algorithm fusion in wireless sensor networks

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Sensors and Transducers 2012年第SPEC. 2期14卷 179-195页

作者： Behnke, Ralf Salzmann, Jakob Gorski, Philipp Timmermann, Dirk Institute of Applied Microelectronics and Computer Engineering University of Rostock Richard-Wagner Straße 31 18119 Rostock Germany

Wireless Sensor Networks (WSNs) have been a growing research domain during the past couple of years. One of the most challenging tasks of WSN research is still location estimation. As a well performing fine grained localization approach, Distributed Least Squares (DLS) was introduced, splitting the localization process in a complex global pre calculation and a simple local post calculation. Nevertheless, as size of pre calculation and cost of computation and communication are increasing with the WSN dimensions, it was shown that this algorithm is unsuitable for large ones. This constraint has been overcome by scalable DLS (sDLS). Further, the computational costs of sDLS have been improved by using sDLSne. Unfortunately, sDLSne comes along with decreased localization accuracy and thus represents a tradeoff. The presented hybrid solution combines sDLSne with various coarse grained localization techniques to avoid this drawback. The resulting localization accuracy overcomes the efficient sDLSne approach as well as the more precise sDLS approach, while computational costs still outperforms sDLS. © 2012 IFSA.

关键词： Wireless sensor networks

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Passive RFID tomographic imaging for device-free user localization

Passive RFID tomographic imaging for device-free user locali...

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Workshop on Positioning, Navigation and Communication, WPNC

作者： Benjamin Wagner Neal Patwari Dirk Timmermann Institute of Applied Microelectronics and Computer Engineering University of Rostock Germany Department of Electrical and Computer Engineering University of Utah Salt Lake USA

Localization of users is an important part of location aware systems and smart environments. It forms a major data source for superimposed intention recognition systems. In RF device-free localization (DFL), the person being tracked does not need to wear a RF transmitter or receiver in order to be located. Instead, they are tracked using the changes in signal strength measured on static links in a wireless network. This work presents a new algorithm for RF DFL using passive RFID networks. We formulate and show how a tomographic imaging algorithm provides both low computational complexity and highly accurate position estimates. Using measurements conducted in an indoor environment with various human positions, we find the algorithm can locate the human with as low as 30 cm mean location error.

关键词： Transponders Radiofrequency identification Antenna measurements Imaging Receivers Antennas Attenuation

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Characteristics of Ti/Pt/Au Ohmic Contacts on p -type GaN/Al x Ga 1−x N Superlattices

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MRS Online Proceedings Library 2012年第1期595卷 1-6页

作者： L. Zhou F. Khan A. T. Ping A. Osinski I. Adesida Microelectronics Laboratory Department of Electrical and Computer Engineering Univ. of Illinois Urbana-Champaign USA NZ Applied Technologies Woburn USA

Ti/Pt/Au metallization on p-type GaN/AlxGa1-xN (x=0.10 and 0.20) superlattices (SL) were investigated as ohmic contacts. Current-voltage and specific contact resistance measurements indicate enhanced p-type doping in the superlattice structures compared to that in GaN. Ti/Pt/Au is shown to be an effective ohmic metallization scheme on p-type GaN/AlxGa1-xN superlattices. A specific contact resistance of Rc = 4.6×10-4 Ω-cm2 is achieved for unalloyed Ti/Pt/Au on GaN/Al0.2Ga0.8N SL. This is reduced to 1.3×10-4 Ω-cm2 after annealing for 5 minutes at 300 °C.

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Multifunction-timing card lTTEV2 for CoDaC systems of Wendelstein 7-X

Multifunction-timing card lTTEV2 for CoDaC systems of Wendel...

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IEEE NPSS Conference on Real Time

作者： J. Schacht J. Skodzik Max Planck Institute of Plasma Physics Greifswald Germany Institute of Applied Microelectronics and Computer Engineering University of Rostock Rostock Germany

The timing system is a crucial element for the CoDaC (Control, Data Acquisition, and Communication) system of the steady state fusion experiment Wendelstein 7-X (W7-X). Its main task is the synchronization of all clocks with sufficient accuracy. Furthermore, it is able to send, receive, and process event messages. It offers a wide range of time related functions, e.g., time capturing, pulse generation, realization of time delays, and sending and receiving of trigger signals. The overall timing system consists of a central timing system and a considerable number of local timing systems. A revision of the existing lTTEV1 and TDC cards was necessary as many components used for their fabrication were no longer available. The need for a bus interface for the lTTE card with long term availability has led to the decision to use a GBit Ethernet interface. By choosing a more powerful FPGA device, it was possible to increase the time resolution by a factor of two. This contribution starts with a short introduction of the W7-X timing system. The key properties, all extended as well as new features of the lTTEV2 card to face new requirements regarding data acquisition are described. The actual state of the development is given.

关键词： Radiation detectors Field programmable gate arrays Registers Data acquisition Random access memory Synchronization

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Device-free user localization utilizing artificial neural networks and passive RFID

Device-free user localization utilizing artificial neural ne...

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Ubiquitous Positioning Indoor Navigation and Location Based Service (UPINLBS)

作者： Benjamin Wagner Dirk Timmermann Gernot Ruscher Thomas Kirste Institute of Applied Microelectronics and Computer Engineering University of Rostock Rostock Germany Mobile Multimedia Information Systems Group University of Rostock Rostock Germany

User localization information is an important data source for ubiquitous assistance in smart environments. This paper proposes a device-free passive user localization approach based on room-equipped passive RFID instead of battery powered hardware. Based on this approach recent work tried to formulate physical model based localization algorithms. These approaches suffer from their inability of integrating environmental changes like the deployment under moving experimental conditions. On the other hand most model based approaches have a certain trade-off between a high localization precision and computational complexity. In this work we try to formulate a training based approach to the problems with the help of artificial neural networks. Special representatives like multi-layered perceptrons are applied to a wide range of problems where it is difficult to model the underlying physical condition completely. We present a perceptron implementation for the purpose of user localization and conduct first results with different model parameters and functions.

关键词： Transponders Training Data models Computational modeling Backpropagation Passive RFID tags Mathematical model

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Decoding of Raptor codes on embedded systems

Decoding of Raptor codes on embedded systems

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作者： Mladenov, Todor Nooshabadi, Saeid Montiel-Nelson, Juan A. Kim, Kiseon Gwangju 500-712 Korea Republic of Gwangju 500-712 Korea Republic of Dept. of Electrical and Computer Engineering Michigan Technological University Houghton MI 49931 United States Institute for Applied Microelectronics University of Las Palmas de Gran Canaria 35017 Las Palmas de Gran Canaria Spain

Raptor codes have been proven very suitable for mobile multimedia content delivery. A systematic Raptor code is employed for the application layer Forward Error Correction (FEC), schemes of the 3rd Generation Partnership Project (3GPP), Multimedia Broadcast/Multicast Service (MBMS) and standard and the IP Datacast over Digital Video Broadcasting (DVB) services. Those services run on mobile devices powered by embedded systems. This paper analyzes the performance, energy profile and resource implication of Raptor decoder on a system on a chip (SoC) platform with a soft-core embedded processor. At the heart of the Raptor decoder for binary erasure channel (BEC) is the decoding of the pre-code. The following three methods are used for that task: Belief Propagation (BP), Gaussian Elimination (GE) and the 3GPP inactivation decoding Gaussian elimination (IDGE). The paper analyzes the error correction capability and the complexity of each algorithm on embedded system. Additionally, the paper investigates how the cache size, matrix memory type and organization affect the algorithms under consideration. Finally, a power and energy dissipation analysis for the operation of the three algorithms under consideration is presented. © 2012 Elsevier B.V. All rights reserved.

关键词： Belief propagation

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Investigation of the Use of Embedded Web Services in Smart Metering Applications

Investigation of the Use of Embedded Web Services in Smart M...

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Annual Conference on IEEE Industrial Electronics Society

作者： Vlado Altmann Jan Skodzik Frank Golatowski Dirk Timmermann University of Rostock Institute of Applied Microelectronics and Computer Engineering

ISBN: (纸本)9781467324199

The actual situation in smart metering is characterized by a coexistence of a large number of proprietary and open standards for wired as well as wireless communication. These standards show low or no interoperability to each other. Therefore, it is very difficult to integrate multi-vendor solutions using one sustainable holistic approach. The proposed approach is to use Web Service technology as an open widespread Internet standard for the creation of a heterogeneous network for smart metering devices. Smart metering is an emerging topic for realizing modern energy policies. Monitoring, analyzing, and controlling of power consumption is the precondition for optimizing energy strategies. This work focuses on the integration of Web Service technology in the area of smart meter communication. Furthermore, mechanisms for reducing Web Service traffic overhead by over 90% is presented.

关键词： Smart Grids Smart Metering Web Services Home Automation

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How much Security for Switching a Light Bulb-The SOA Way

How much Security for Switching a Light Bulb-The SOA Way

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International Wireless Communications and Mobile Computing Conference

作者： Sebastian Unger Stefan Pfeiffer Dirk Timmermann Institute of Applied Microelectronics and Computer Engineering University of Rostock Germany

ISBN: (纸本)9781457713781;9781457713798

What visions of technologies such as the Internet of Things (IoT), Pervasive Computing (PC) or Ambient Intelligence(AI) have in common is that they employ a very high amount of critically resource-constrained devices. This of course raises a whole set of new security challenges. Instead of proposing another middleware for IoT, PC or AI, and presenting a security approach for it we focus on existing, widely-adopted security mechanisms and concepts and give a comprehensive overview. Furthermore, we examine the Web Service security suite as an example for a comprehensive security framework on application level. We use an intentionally kept simple scenario including light bulbs and switches to demonstrate necessary security mechanisms and properties and to judge applicability of the presented existing security techniques and frameworks.

关键词： Devices Profile for Web Services DPWS Internet of Things Pervasive Computing Security SOA for devices

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A lightweight SOAP over CoAP transport binding for resource constraint networks

A lightweight SOAP over CoAP transport binding for resource ...

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8th IEEE International Conference on Mobile Ad-hoc and Sensor Systems, MASS 2011

作者： Moritz, Guido Golatowski, Frank Timmermann, Dirk University of Rostock Institute of Applied Microelectronics and Computer Engineering 18055 Rostock Germany

ISBN: (纸本)9780769544694

A huge momentum towards IP enabled Wireless Sensor Networks (WSN) appeared through the emerging 6LoWPAN protocols (i.e. IPv6 over Low power Wireless Personal Area Networks). By using existing cross domain open standards in contrast of proprietary solutions, technologies and deployments are not tailored too tight for specific applications. Nevertheless, 6LoWPAN is only the first step. Still efforts on higher layers on top of 6LoWPAN are an urgent need to provide the seamless connectivity and interaction of highly resource constrained devices with higher valued applications and services. This paper describes a new approach to bind SOAP to the emerging Constrained Application Protocol (CoAP) protocol. Thereby, CoAP provides a lightweight but reliable transport binding for SOAP. Compared to the widespread TCP based HTTP binding, round trip times can be reduced by 43% in an exemplary scenario because of the omitted expensive bidirectional TCP handshake mechanisms. Combined with dedicated XML compressors like EXI, SOAP based protocols become also applicable in WSNs. © 2011 IEEE.

关键词： Wireless sensor networks

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