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IEEE Conference on Vehicular technology (VTC)

作者： Khoa Quang Huynh Tor Aulin Telecommunication Theory Research Group Department of Computer Science and Engineering Chalmers University of Technology Gothenburg Sweden

An Improved Maximum A Posteriori (IMAP) decoder for turbo-coded decode-and-forward (DF) relay channels which takes into account the decoding errors at the relay is analyzed. This decoder is implemented in an iterative manner similar to the traditional iterative decoder (TID) used for turbo codes. The performance of this IMAP decoder is compared with the performance of an iterative decoder normally used in the literature which does not take into account the decoding errors at the relay, by simulation. The comparison shows that although the proposed IMAP decoder provides a better performance, especially when many decoding errors occur at the relay, the improvement is not significant. Then, another heuristic modification for the iterative decoder is proposed. In spite of the lack of theoretical analysis, the numerical results show that the proposed heuristically modified iterative decoder (HMID) gives significantly better performance than the traditional one.

关键词： Relays Iterative decoding Turbo codes Signal to noise ratio Convolutional codes Maximum likelihood decoding

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The DeSyRe project: On-demand system reliability

The DeSyRe project: On-demand system reliability

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15th Euromicro Conference on Digital System Design, DSD 2012

作者： Sourdis, I. Strydis, C. Bouganis, C.S. Falsafi, B. Gaydadjiev, G.N. Malek, A. Mariani, R. Pnevmatikatos, D. Pradhan, D.K. Rauwerda, G. Sunesen, K. Tzilis, S. Chalmers University of Technology Computer Science and Engineering Dept. Sweden University of Bristol Computer Science Dept. United Kingdom École Polytechnique Fédérale de Lausanne Computer and Communication Sciences EPFL Switzerland Greece Imperial College London Electrical and Electronic Engineering Dept. United Kingdom Neurasrnus B.V. Netherlands Yogitech SpA Italy Recore Systems B.V. Netherlands

ISBN: (纸本)9780769547985

The DeSyRe project builds on-demand adaptive and reliable Systems-on-Chips (SoCs). As fabrication technology scales down, chips are becoming less reliable, thereby incurring increased power and performance costs for fault tolerance. To make matters worse, power density is becoming a significant limiting factor in SoC design, in general. In the face of such changes in the technological landscape, current solutions for fault tolerance are expected to introduce excessive overheads in future systems. Moreover, attempting to design and manufacture a totally defect-/fault-free system, would impact heavily, even prohibitively, the design, manufacturing, and testing costs, as well as the system performance and power consumption. In this context, DeSyRe will deliver a new generation of systems that are reliable by design at well-balanced power, performance, and design costs. © 2012 IEEE.

关键词： System-on-chip

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A Light-Weight Defect Classification Scheme for Embedded Automotive Software and Its Initial Evaluation

A Light-Weight Defect Classification Scheme for Embedded Aut...

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International Symposium on Software Reliability engineering (ISSRE)

作者： Niklas Mellegård Miroslaw Staron Fredrik Törner Software Engineering Division Chalmers University of Technology Sweden Department of Computer Science and Engineering University of Gothenburg Sweden Volvo Car Corporation Sweden

Objective: Defect classification is an essential part of software development process models as a means of early identification of patterns in defect inflow profiles. Such classification, however, may often be a tedious task requiring analysis work in addition to what is necessary to resolve the issue. To increase classification efficiency, adapted schemes are needed. In this paper a light-weight defect classification scheme adapted for minimal process footprint -- in terms of learning and classification effort -- is proposed and initially evaluated. Method: A case study was conducted at Volvo Car Corporation to adapt the IEEE Std. 1044 for automotive embedded software. An initial evaluation was conducted by applying the adapted scheme to defects from an existing software product with industry professionals as subjects. Results: The results showed that the classification scheme was quick to learn and understand -- required classification time stabilized around 5-10 minutes already after practicing on 3-5 defects. The results also showed that the patterns in the classified defects were interesting for the professionals, although in order to apply statistical methods more data was needed. Conclusions: We conclude that the adapted classification scheme captures what is currently tacit knowledge and has the potential of revealing patterns in the defects detected in different project phases. Furthermore, we were, in the initial evaluation, able to contribute with new information about the development process. As a result we are currently in the process of incorporating the classification scheme into the company's defect reporting system.

关键词： Software IEEE standards Documentation Safety Context Testing Companies

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Efficient algorithms for calculating Euclidean distance spectra of muliti-user continuous phase modulation systems

Efficient algorithms for calculating Euclidean distance spec...

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IEEE International Symposium on Information Theory

作者： Li Bing Tor Aulin Baoming Bai State Key Laboratory of ISN Xidian University Xi'an Shaanxi China Computer Science and Engineering Chalmers University of Technology Goteborg Sweden

ISBN: (纸本)9781467325806

The performance of maximum likelihood detection of a coded modulation scheme over an additive white Gaussian noise channel can be predicted precisely by its Euclidean distance spectrum. In this paper, three algorithms are developed to generate the Euclidean distance spectra. The first algorithm is an exhaustive tree-search algorithm which is simplified by exploiting the correspondence between a code tree and the trellis. This algorithm is then modified to incorporate the A* algorithm and results in two heuristic algorithms. Moreover, the technique of trellis minimization is further developed for the multi user case and employed to reduce the complexity and memory requirements. Numerical results confirm that the proposed algorithms can generate the distance spectra of all systems with lower complexity relative to previous methods and are particularly suited for multi user CPM systems.

关键词： Minimization Complexity theory Euclidean distance Heuristic algorithms Memory management Algorithm design and analysis Merging

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Runtime safety analysis for safe reconfiguration

Runtime safety analysis for safe reconfiguration

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IEEE International Conference on Industrial Informatics (INDIN)

作者： Claudia Priesterjahn Christian Heinzemann Wilhelm Schäfer Matthias Tichy Heinz Nixdorf Institute and Department of Computer Science Software Engineering Group University of Paderborn Paderborn Germany Software Engineering Division Chalmers University of Technology and University of Gothenborg Gothenburg Sweden

ISBN: (纸本)9781467303125

Modern technical systems are increasingly built to exhibit self-x properties as, e.g., self-healing or self-optimization. For this, they require adaptation at runtime. This is even true for embedded or mechatronic systems which often operate in safety-critical environments. There, the effects of the adaptation with respect to safety must be analyzed carefully. However, not all parameters needed for safety analyses, e.g., the concrete system architecture, are known at design time. Consequently, safety analyses need to be executed during runtime. Current approaches of runtime safety analysis typically react to anomalies that already occurred in the system. Thus, unsafe system states cannot be excluded completely. We present a runtime safety analysis that prevents system states with an unacceptable risk that have not yet occurred. For this, we generate the reachable component structures at runtime and analyze them with respect to risk. The system is modified such that component structures with an unacceptable risk are not reachable any more and are thus prevented.

关键词： Hazards Vehicles Runtime Real time systems Sensors Unified modeling language

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Sum rate analysis of ZF receivers in distributed MIMO systems with Rayleigh/Lognormal fading

Sum rate analysis of ZF receivers in distributed MIMO system...

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IEEE International Conference on Communications

作者： Michail Matthaiou Caijun Zhong Matthew R. McKay Tharm Ratnarajah Department of Signals and Systems Chalmers University of Technology Institute of Information and Communication Engineering Zhejiang University Department of Electronic and Computer Engineering Hong Kong University of Science and Technology Institute of Electronics Communications and Information Technology (ECIT) Queen's University Belfast

ISBN: (纸本)9781457720529

This paper presents a detailed sum rate characterization of distributed multiple-input multiple-output systems operating over composite fading channels and employing linear zero-forcing receivers. We consider the Rayleigh/Lognormal fading model and also take into account the effects of path-loss and spatial correlation at the transmit side. New closed-form upper and lower bounds on the achievable sum rate are proposed that apply for arbitrary numbers of antennas. Moreover, we investigate the concept of large-scale multiple-antenna systems when the number of receive antennas grow large. In this asymptotic regime, it is shown that the effects of Rayleigh fading are averaged out and the channel is dominated by the much more slowly varying shadowing. An interesting observation from our results is that in order to maximize capacity, the radio ports should be placed at unequal distances to the base station when they experience the same level of shadowing.

关键词： distributed MIMO systems Rayleigh fading Shadowing (Histology) sums fading color Receivers Fading channels zero frequency output system BASE STATION multiple input multiple output systems ANTENNA Lower bound

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Parallelizing more Loops with Compiler Guided Refactoring

Parallelizing more Loops with Compiler Guided Refactoring

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International Conference on Parallel Processing (ICPP)

作者： Per Larsen Razya Ladelsky Jacob Lidman Sally A. McKee Sven Karlsson Ayal Zaks DTU Informatics Technical University of Denmark Kongens Lyngby Denmark Mount Carmel IBM Haifa Research Laboratories Haifa Israel Computer Science Engineering Chalmers University of Technology Gothenburg Sweden Intel Corporation Haifa Israel

The performance of many parallel applications relies not on instruction-level parallelism but on loop-level parallelism. Unfortunately, automatic parallelization of loops is a fragile process, many different obstacles affect or prevent it in practice. To address this predicament we developed an interactive compilation feedback system that guides programmers in iteratively modifying their application source code. This helps leverage the compiler's ability to generate loop-parallel code. We employ our system to modify two sequential benchmarks dealing with image processing and edge detection, resulting in scalable parallelized code that runs up to 8.3 times faster on an eight-core Intel Xeon 5570 system and up to 12.5 times faster on a quad-core IBM POWER6 system. Benchmark performance varies significantly between the systems. This suggests that semi-automatic parallelization should be combined with target-specific optimizations. Furthermore, comparing the first benchmark to manually-parallelized, hand-optimized pthreads and OpenMP versions, we find that code generated using our approach typically outperforms the pthreads code (within 93-339%). It also performs competitively against the OpenMP code (within 75-111%). The second benchmark outperforms manually-parallelized and optimized OpenMP code (within 109-242%).

关键词： Benchmark testing Arrays Kernel Optimization Image edge detection Production Radiation detectors

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The DeSyRe Project: On-Demand System Reliability

The DeSyRe Project: On-Demand System Reliability

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Euromicro Symposium on Digital System Design

作者： I. Sourdis C. Strydis C.S. Bouganis B. Falsafi G.N. Gaydadjiev A. Malek R. Mariani D. Pnevmatikatos D.K. Pradhan G. Rauwerda K. Sunesen S. Tzilis Computer Science and Engineering Dept. Chalmers University of Technology Sweden Ncurasmus B.V. The Netherlands Electrical and Electronic Engineering Dept. Imperial College London UK École Polytechnique Fédérale de Lausanne Computer and Communication Sciences EPFL Switzerland Yogitech SpA Italy Foundation for Research and Technology - Hellas (FORTH) Institute of Computer Science (ICS) Greece Computer Science Dept. University of Bristol UK Recore Systems B.V. The Netherlands

关键词： Digital systems

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Improved Iterative Decoder for Distributed Turbo Trellis Coded Modulation Decode-and-Forward Relay Channels

Improved Iterative Decoder for Distributed Turbo Trellis Cod...

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International Symposium on Wireless Communication Systems

作者： Khoa Quang Huynh Tor Aulin Telecommunication Theory Research Group Department of Computer Science and Engineering Chalmers University of Technology Gothenburg Sweden

ISBN: (纸本)9781467307611

An improved iterative decoder (IID) for 3-node decode-and-forward (DF) relay channels employing distributed turbo trellis coded modulation (DTTCM) schemes which takes into account the decoding errors at the relay is proposed. The principle idea is to modify the extrinsic information between the component decoders to eliminate the effect of error propagation between the decoders, depending on the channel conditions between the source, the relay and the destination nodes in terms of signal-to-noise ratio (SNR) per bit. The performance of this decoder is compared with the performance of an iterative decoder proposed in the literature which is called normal iterative decoder (NID) in this paper and does not take into account the decoding errors at the relay, by simulation. The comparison shows that the IID outperforms the NID when the source-relay channel is bad with low SNR, thus yielding lots of decoding errors at the relay.

关键词： turbo trellis coded modulation iterative decoder decode-and-forward relay channels

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Combining scanning haptic microscopy and fibre optic Raman spectroscopy for tissue characterization

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Journal of Medical engineering and technology 2012年第6期36卷 319-327页

作者： Candefjord, S. Murayama, Y. Nyberg, M. Hallberg, J. Ramser, K. Ljungberg, B. Bergh, A. Lindahl, O.A. Department of Computer Science Electrical and Space Engineering Luleå University of Technology 971 87 Luleå Sweden Centre for Biomedical Engineering and Physics Luleå University of Technology Umeå University Luleå and Umeå Sweden Signals and Systems Chalmers University of Technology 412 96 Gothenburg Sweden MedTech West Sahlgrenska University Hospital Blå Stråket 7 413 45 Gothenburg Sweden Department of Electrical and Electronics Engineering College of Engineering Nihon University Fukushima Japan Department of Surgical and Perioperative Science Urology and Andrology Umeå University Umeå Sweden Department of Medical Biosciences Pathology Umeå University Umeå Sweden Department of Radiation Sciences/Biomedical Engineering Umeå University 901 87 Umeå Sweden

The tactile resonance method (TRM) and Raman spectroscopy (RS) are promising for tissue characterization in vivo. Our goal is to combine these techniques into one instrument, to use TRM for swift scanning, and RS for increasing the diagnostic power. The aim of this study was to determine the classification accuracy, using support vector machines, for measurements on porcine tissue and also produce preliminary data on human prostate tissue. This was done by developing a new experimental set-up combining micro-scale TRMscanning haptic microscopy (SHM)for assessing stiffness on a micro-scale, with fibre optic RS measurements for assessing biochemical content. We compared the accuracy using SHM alone versus SHM combined with RS, for different degrees of tissue homogeneity. The cross-validation classification accuracy for healthy porcine tissue types using SHM alone was 6581%, and when RS was added it increased to 8187%. The accuracy for healthy and cancerous human tissue was 6770% when only SHM was used, and increased to 7277% for the combined measurements. This shows that the potential for swift and accurate classification of healthy and cancerous prostate tissue is high. This is promising for developing a tool for probing the surgical margins during prostate cancer surgery. © 2012 Informa UK, Ltd.

关键词： Raman spectroscopy

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