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Evaluation of the Stretch S6 Hybrid Reconfigurable Embedded CPU Architecture for Power-Efficient Scientific Computing

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Procedia Computer Science 2012年 9卷 196-205页

作者： Thang Viet Huynh Manfred Mücke Wilfried N. Gansterer Graz University of Technology Signal Processing and Speech Communication Lab (SPSC) University of Vienna Research Group Theory and Applications of Algorithms (TAA)

Embedded CPUs typically use much less power than desktop or server CPUs but provide limited or no support for floating-point arithmetic. Hybrid reconfigurable CPUs combine fixed and reconfigurable computing fabrics to balance better execution performance and power consumption. We show how a Stretch S6 hybrid reconfigurable CPU (S6) can be extended to natively support double precision floating-point arithmetic. For lower precision number formats, multiple parallel arithmetic units can be implemented. We evaluate if the superlinear performance improvement of floating-point multiplication on reconfigurable fabrics can be exploited in the framework of a hybrid reconfigurable CPU. We provide an in-depth investigation of data paths to and from the S6 reconfigurable fabric and present peak and sustained throughput as a function of wide registers used and total operand size. We demonstrate the effect of the given interface when using a floating-point fused multiply-accumulate (FMA) SIMD unit to accelerate the LINPACK benchmark. We identify a mismatch between the size of the S6s reconfigurable fabric and the available interface bandwidth as the major bottleneck limiting performance which makes it a poor choice for scientific workloads relying on native support for floating-point arithmetic.

关键词： Scientific Computing Floating-Point Arithmetic Power-Aware Computing LINPACK Reconfigurable Hardware Computer Architecture

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Accommodation of NLOS for ultra-wideband TDOA localization in single- and multi-robot systems

Accommodation of NLOS for ultra-wideband TDOA localization i...

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International Conference on Indoor Positioning and Indoor Navigation (IPIN)

作者： Amanda Prorok Phillip Tomé Alcherio Martinoli Distributed Intelligent Systems and Algorithms Laboratory School of Architecture Civil and Environmental Engineering Ecole Polytechnique Fédérale de Lausanne Switzerland Electronics and Signal Processing Laboratory School of Engineering Ecole Polytechnique Fédérale de Lausanne Switzerland

Ultra-wideband (UWB) localization is one of the most promising indoor localization methods. Yet, non-line-of-sight (NLOS) positioning scenarios can potentially cause significant localization errors and remain a challenge. In this work, we propose a novel, probabilistic UWB TDOA error model which explicitly takes into account NLOS. In order to validate our approach systematically in a real world setup, we leverage the utility of a group of mobile robots, and introduce our error model into a real-time localization framework run onboard the robots. We subsequently extend our framework by employing a collaborative localization strategy which enables the sharing of inter-robot, relative position observations. Our experimental results show how the novel TDOA error model is able to improve localization performance when information on the LOS/NLOS path condition is available. These results are complemented by additional experiments which show how a collaborative team of robots is able to significantly improve localization performance when no information on the LOS/NLOS path condition is available.

关键词： Robot kinematics Mathematical model Robot sensing systems Measurement uncertainty Atmospheric measurements Particle measurements

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Iterative suppression of co-channel interference

Iterative suppression of co-channel interference

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17th European signal processing Conference, EUSIPCO 2009

作者： Nisar, M. Danish Nottensteiner, Hans Utschick, Wolfgang Technical University Munich Institute for Signal Processing Munich Germany Nokia Siemens Networks Radio Access Algorithms and Simulations Munich Germany

Co-Channel Interference (CCI) is one of the major bottlenecks in the performance of today's densely planned wireless cellular systems. A receiver equipped with multiple receive antennas and sufficient computational budget typically exploits the spatial dimension and iterative processing between the detector and the channel decoder to suppress this interference. In this paper, we propose modifications in the standard iterative turbo processing based CCI suppression to especially boost the receiver performance in a dominant CCI scenario. Performance gains of 3-5 dB are shown to be achieved over the conventional iterative approaches for an LTE uplink system. © EURASIP, 2009.

关键词： Receiving antennas

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ITERATIVE SUPPRESSION OF CO-CHANNEL INTERFERENCE

ITERATIVE SUPPRESSION OF CO-CHANNEL INTERFERENCE

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European signal processing conference

作者： M. Danish Nisar Hans Nottensteiner Wolfgang Utschict Technical University Munich Associate Institute for Signal Processing Munich GermanyNokia Siemens Networks Radio Access Algorithms & Simulations Munich Germany Nokia Siemens Networks Radio Access Algorithms & Simulations Munich Germany Technical University Munich Associate Institute for Signal Processing Munich Germany

ISBN: (纸本)9781617388767

关键词： iterative receiver turbo equalization interference suppression Co-channel interference Channel Decoder Iterative Wireless cellular systems Cochannel interference Iterative Process Receivers Receiving antennas

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Robust 2-D channel estimation for multi-carrier systems with finite dimensional pilot grid

Robust 2-D channel estimation for multi-carrier systems with...

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International Conference on Acoustics, Speech, and signal processing (ICASSP)

作者： M. Danish Nisar Wolfgang Utschick Thomas Hindelang Radio Access Algorithms & Simulations Nokia Siemens Networks Munich Germany Associate Institute of Signal Processing Technical University Munich Munich Germany

Pilot-aided channel estimation for multi-carrier systems can be significantly improved by exploiting time and frequency correlations between the channel frequency response coefficients. But in practice, the knowledge of channel correlation function is not accurately available, thereby necessitating the need of an estimator that employs a fixed correlation function and is robust to mismatches with the actual one. While the maximally robust channel estimator for multi-carrier systems for the case of an infinite number of observations is well known for almost a decade, the one for the case of a finite number of observations has been only recently proposed. We extend the proposed maximally robust estimator to the practical case of small finite dimensional pilot grids by taking into account the grid edge effects. This paves the way for application of the estimator to practical systems such as 3G LTE. Simulation results for an LTE uplink system under different transmission scenarios demonstrate the superiority of the proposed maximally robust estimator over the heuristic one by as much as 1.35 dB in terms of the coded BER.

关键词： Robustness Channel estimation Frequency estimation Delay estimation Degradation signal processing algorithms Minimax techniques Bit error rate Frequency response Maximum likelihood estimation

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Architectural Requirements of Parallel Computational Biology Applications with Explicit Instruction Level Parallelism 20

Architectural Requirements of Parallel Computational Biology...

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20th International Conference on Parallel and Distributed Computing Systems, PDCS 2007

作者： Azeemi, Naeem Z. Christian Doppler Laboratory for Design Methodology of Signal Processing Algorithms Institute of Communications and Radio Frequency Engineering University of Technology Vienna Austria

ISBN: (纸本)9781604233926

Computational biology applications expression profile is a critical performance metric in high end genomic data processing. These profiles are compute intensive and offers a wide range of computation pattern ranging from data base searching applications to highly irregular phylogenetic trees. Such debilitating factors lead to poor architecture-application correlation. A prior knowledge of software application would be very useful to exploit the instruction level parallelism inside the computational biology applications. This paper presents an integrated approach for parameterized workload characterization and trace driven simulation at a high end multimedia processor in bioinformatics applications. A set of sixteen widely used bioinformatics applications is selected as benchmark. Software monitoring techniques are used to collect execution traces. Based on the measured results, we investigate both the computation and communication behavior of these applications, including execution time, functional unit utilization, scheduling factors and cache misses. The temporal and spatial localities in gnomic data are also discussed. Experimental results are measured at a high end SIMD (single instruction stream over multiple data stream) processor. © 20th International Conference on Parallel and Distributed Computing Systems, PDCS 2007. All rights reserved.

关键词： Application programs

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Evaluation of Architectural Support for Speech Codecs Application in Large-Scale Parallel Machines 20

Evaluation of Architectural Support for Speech Codecs Applic...

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20th International Conference on Parallel and Distributed Computing Systems, PDCS 2007

作者： Azeemi, Naeem Zafar Christian Doppler Laboratory for Design Methodology of Signal Processing Algorithms Institute of Communications and Radio Frequency Engineering University of Technology Vienna Gusshausstrasse 25/389 ViennaA-1040 Austria

ISBN: (纸本)9781604233926

Next generation multimedia mobile phones that use the high bandwidth 3G cellular radio network consume more power. Multimedia algorithms such as speech, video transcodecs have very large instruction foot prints and consequently stalled due to instruction cache misses. The conflicts in on-chip caches contribute a large fraction of the CPU cycle penalty and hence increase in power consumption. Many commercial tools are developed to minimize such cache misses by adequately placing the frequently called procedures in an application. Followed by profile extraction, these tools use cache line coloring and post compilation techniques for cache hit optimization. The major impediment in the optimal performance of such tools is their static layout profile, which does not consider the dynamic behavior of the application. We propose a methodology called DCP (dynamic code placement) for positioning code at run time for good instruction cache performance and have implemented in high end processors. The dynamic application profile is completely transparent to the developer’s code. This technique optimizes the code footprint in memory layout of a program. It improves i-cache mapping to increase the number of cache hits and eventually reduce the CPU stalls. Our optimization is powered with static as well as detail run time profile information that extracts the relevant, temporal behavior of the applications. Moreover, while mapping code in instruction cache, the effect of inter-procedural code positioning is also considered. Improvement over the Pettis and Hansen approach (PH) is also shown in results. Though majority of multimedia applications can be optimized by our framework, application dominated with the function pointers do not work correctly. The technique incurs low overheads and enhances the cache hits architecture correlation. For a range of applications we show that instruction miss rates can be reduced by 19-68%. Using a simple model this corresponds to execution time re

关键词： Embedded systems

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Evaluation and comparison of different methods of ionospheric delay mitigation for future Galileo mass market receivers

Evaluation and comparison of different methods of ionospheri...

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20th International Technical Meeting of the Satellite Division of The Institute of Navigation 2007 ION GNSS 2007

作者： Somieski, A. Bürgi, C. Favey, E. u-blox AG Thalwil Switzerland GNSS Software u-blox AG Thalwil Switzerland Algorithms and Signal Processing Group u-blox AG Thalwil Switzerland Navigation Software Development u-blox AG Thalwil Switzerland

ISBN: (纸本)9781605600697

The Earth's ionosphere causes strongly varying range and range - rate errors in the measurements of ground - based GNSS receivers and is, therefore, a limiting factor for single - frequency GNSS applications. Single - frequency users have to rely on ionospheric models or Satellite Based Augmentation Systems (SBAS) in order to mitigate errors due to ionospheric refraction sufficiently. In the framework of the EU funded project Galileo Receivers for Mass Market (GREAT) a preliminary navigation study was carried out dealing with the performance of the future Galileo ionospheric model NeQuick proposed to calculate corrections for single - frequency Galileo users. Primarily, this study intends to clarify if the effort for a dual - frequency Galileo receiver for mass market pays in terms of improved perfor-manee due to advanced mitigation of ionospheric refraction. The additional work and expense of the dual - frequency approach has to be related to the benefit from enhanced ionospheric corrections. In this context, the quality of the future ionospheric model of Galileo plays an important role, since it affects directly the positioning accuracy of a single - frequency Galileo user. Therefore, the Galileo model NeQuick is investigated in detail and compared to common methods accounting for ionospheric effects. Secondly, the "ionospheric" linear combination is applied to code measurements (C1 and P2) of the Global Positioning System (GPS) in order to evaluate the potential of a Galileo receiver performing code measurements on El and E5a. According to the Galileo Interface Control Document (ICD), the main input parameter of NeQuick is the effective ionization level Az, which is approximated with a second - degree polynomial function of the modified dip latitude MODIP. The three coefficients of this polynom are supposed to be determined on a daily basis utilizing a future global network of Galileo tracking stations. Since these Az coefficients are not yet available they have

关键词： Global positioning system

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The squaring-loss paradox

The squaring-loss paradox

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20th International Technical Meeting of the Satellite Division of The Institute of Navigation 2007 ION GNSS 2007

作者： Strässle, Cassian Megnet, Daniel Mathis, Heinz Bürgi, Clemens University of Applied Sciences Rapperswil Switzerland u-blox AG Thalwil Switzerland University of Applied Sciences Rapperswil Switzerland Department of Mobile Communications University of Applied Sciences Rapperswil Switzerland Algorithms and Signal Processing Group u-blox

ISBN: (纸本)9781605600697

Much confusion has been created by the fact that negative squaring losses were reported in documents comparing SNR obtained from non-coherent and coherent integration methods. In the quest for a more consistent measure of the squaring loss, which approaches zero as the presquaring SNR increases, statistical detection probabilities have to be employed. This paper compares the traditional definitions of SNR before and after squaring with more statistical means of measuring detection success. The comparison of SNR values for different amplitude distributions is tricky and results in the paradox situation that the squaring operation can increase the SNR leading one to believe that the detection probability is improved by taking the signal into the square operation. Thus, we present a unifying measure to compare the coherent with non-coherent detection without a discrepancy for the high-SNR situation. Theoretical expressions evaluated numerically confirm well with MonteCarlo simulations. Examples of GPS C/A codes are given.

关键词： Probability distributions

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Architecture-Aware Hierarchical Probabilistic Source Optimization 19

Architecture-Aware Hierarchical Probabilistic Source Optimiz...

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19th International Conference on Parallel and Distributed Computing Systems, PDCS 2006

作者： Azeemi, N.Z. Christian Doppler Laboratory for Design Methodology of Signal Processing Algorithms Institute of Communications and Radio Frequency Engineering University of Technology Vienna Gusshausstrasse 25/389 ViennaA-1040 Austria

ISBN: (纸本)9781604236446

This paper focuses on architecture-aware source-level code transformation methods for low energy consumption in complex VLIW processors. Though energy issue has long been addressed at hardware level, but a significant contribution of software applications can not be ignored. Successive energy-cycle cost guarded parametric optimization are applied in proposed iterative compilation environment to evaluate an application expression profile on complex multimedia processors. The optimization is based on a multi objective function. The constraints of this objective function are formulated using a penalty method;a genetic algorithm finds solutions eventually. The proposed new code transformation methodology determines appropriate parameters for compiler optimization in order to satisfy user constraints on code size, energy, execution time and optimal target architecture usage. The set of experiments presented here characterize the newly introduced approach, while giving an idea about the architecture-based energy-cycle performance issues. Experimental results show that our approach reduces cache misses by an average of 33% (max. 67%), improves typically energy dissipation up to 23% and CPU performance up to 80% for an MPEGdec video algorithm. The approach is general and can easily be integrated in multimedia processor compilers. © 19th International Conference on Parallel and Distributed Computing Systems 2006, PDCS 2006. All rights reserved.

关键词： Energy dissipation

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