Graz University of Technology

Displaying 1-40 of 59 results

  • White Papers // Apr 2014

    Deriving Shape Grammars on the GPU

    Due to growing demand for computer generated graphical content, procedural modeling has become an important topic in the gaming and movie industry. Creating vast amounts of content by hand requires excessive amounts of manual labor. Using a procedural rule set, entire worlds can be generated by a computer. However, the...

    Provided By Graz University of Technology

  • White Papers // Dec 2013

    Blank Digital Signatures

    In this paper the authors present a novel type of digital signatures, which they call blank digital signatures. The basic idea behind this scheme is that an originator can define and sign a message template, describing fixed parts of a message as well as multiple choices for exchangeable parts of...

    Provided By Graz University of Technology

  • White Papers // Sep 2013

    Improved Cryptanalysis of Reduced RIPEMD-160

    In this paper, the authors propose an improved cryptanalysis of the double-branch hash function standard RIPEMD-160. Using a carefully designed non-linear path search tool, they study the potential differential paths that can be constructed from a difference in a single message word and show that some of these message words...

    Provided By Graz University of Technology

  • White Papers // Aug 2013

    Warrant-Hiding Delegation-by-Certificate Proxy Signature Schemes

    Proxy signatures allow an entity (the delegator) to delegate the user signing capabilities to other entities (called proxies), who can then produce signatures on behalf of the delegator. Typically, a delegator may not want to give a proxy the power to sign any message on their behalf, but only messages...

    Provided By Graz University of Technology

  • White Papers // Jul 2013

    Efficient Simultaneous Privately and Publicly Verifiable Robust Provable Data Possession from Elliptic Curves

    When outsourcing large sets of data to the cloud, it is desirable for clients to efficiently check, whether all outsourced data is still retrievable at any later point in time without requiring to download all of it. Provable Data Possession (PDP)/Proofs of Retrievability (PoR), for which various constructions exist, are...

    Provided By Graz University of Technology

  • White Papers // Jul 2013

    Pushing the Limits of SHA-3 Hardware Implementations to Fit on RFID

    There exists a broad range of RFID protocols in literature that propose hash functions as cryptographic primitives. Since keccak has been selected as the winner of the NIST SHA-3 competition in 2012, there is the question of how far the authors can push the limits of keccak to fulfill the...

    Provided By Graz University of Technology

  • White Papers // Jun 2013

    FIDES: Lightweight Authenticated Cipher with Side-Channel Resistance for Constrained Hardware

    In this paper, the authors present a novel lightweight authenticated cipher optimized for hardware implementations called fides. It is an online nonce-based authenticated encryption scheme with authenticated data whose area requirements are as low as 793 GE and 1001 GE for 80-bit and 96-bit security, respectively. This is at least...

    Provided By Graz University of Technology

  • White Papers // Nov 2012

    Signal Enhancement as Minimization of Relevant Information Loss

    The authors introduce the notion of relevant information loss for the purpose of casting the signal enhancement problem in information-theoretic terms. They show that many algorithms from machine learning can be reformulated using relevant information loss, which allows their application to the aforementioned problem. As a particular example they analyze...

    Provided By Graz University of Technology

  • White Papers // Oct 2012

    Repair with On-The-Fly Program Analysis

    In this paper, the authors present a novel automatic repair approach for incorrect programs. It applies formal methods and analyzes program behavior only on demand. They argue that this is beneficial, especially if exhaustive program analysis is infeasible. Their approach computes repair candidates and refines them based on counterexamples. It...

    Provided By Graz University of Technology

  • White Papers // Oct 2012

    Trading Approximation Quality Versus Sparsity Within Incremental Automatic Relevance Determination Frameworks

    In this paper a trade-off between sparsity and approximation quality of models learned with Incremental Automatic Relevance Determination (IARD) is addressed. An IARD algorithm is a class of Sparse Bayesian Learning (SBL) schemes. It permits an intuitive and simple adjustment of estimation expressions, with the adjustment having a simple interpretation...

    Provided By Graz University of Technology

  • White Papers // Jul 2012

    Relative Information Loss in the PCA

    In this paper, the authors analyze Principle Component Analysis (PCA) as a deterministic input-output system. They show that the relative information loss induced by reducing the dimensionality of the data after performing the PCA is the same as in dimensionality reduction without PCA. Furthermore, they analyze the case where the...

    Provided By Graz University of Technology

  • White Papers // Jun 2012

    Beamforming Using Uniform Circular Arrays for Distant Speech Recognition in Reverberant Environments and Double-Talk Scenarios

    Beamforming is crucial for hands-free mobile terminals and voice-enabled automated home environments based on distant-speech interaction to mitigate causes of system degradation, e.g., interfering noise sources or competing speakers. This paper presents an adaptation of the most common state-of-the-art broadband beamformers to uniform circular arrays, such that competing speakers are...

    Provided By Graz University of Technology

  • White Papers // Jun 2012

    Tracking of UWB Multipath Components Using Probability Hypothesis Density Filters

    In Multipath assisted Indoor Navigation and Tracking (MINT), individual Multi-Path Components (MPCs) of the Ultra WideBand (UWB) channel needs to be extracted. A sequential Monte-Carlo based implementation of the multi-source multi-target Probability Hypothesis Density (PHD) filter is used in order to jointly estimate the number of multipath components present as...

    Provided By Graz University of Technology

  • White Papers // Jun 2012

    Analysis of Nonideal Multipliers for Multichannel Autocorrelation UWB Receivers

    Non-coherent UWB receivers promise low power consumption and low processing complexity but their peak data rate is limited by the delay spread of the multipath radio channel. A recently proposed multichannel Autocorrelation Receiver (AcR) can break this rate limit due to its multicarrier signal demodulation capability. In this paper, the...

    Provided By Graz University of Technology

  • White Papers // May 2012

    Performance Bounds for Multipath-Assisted Indoor Navigation and Tracking (MINT)

    The MINT (Multipath-assisted Indoor Navigation and Tracking) problem exploits the geometry of deterministic Multi-Path Components (MPCs) for robust indoor positioning in Line-Of-Sight (LOS) and non-LOS situations. It assumes a known room layout and can thus easily make use of signals reflected by the walls, for instance. In this paper, the...

    Provided By Graz University of Technology

  • White Papers // Apr 2012

    Functional Magnetic Resonance Imaging and the Challenge of Balancing Human Security with State Security

    Recent reports reveal that violent extremists are trying to obtain insider positions that may increase the impact of any attack on critical infrastructure and could potentially endanger state services, people's lives and even democracy. It is of utmost importance to be able to adopt extreme security measures in certain high-risk...

    Provided By Graz University of Technology

  • White Papers // Mar 2012

    Capacity and Capacity-Achieving Input Distribution of the Energy Detector

    This paper presents the capacity-achieving input distribution of an energy detection receiver structure. A proper statistical model is introduced which makes it possible to treat the energy detector as a constrained continuous communication channel. To solve this non-linear optimization the authors used the Blahut-Arimoto algorithm extended with a particle method,...

    Provided By Graz University of Technology

  • White Papers // Mar 2012

    State-of-Charge Measurement Error Simulation for Power-Aware Wireless Sensor Networks

    Wireless Sensor Networks (WSNs) are power critical systems, because they are used in application areas without wired infrastructure. Each sensor node needs a dedicated power supply. Today's protocols and applications for WSNs are often power-aware. However, the State-of-Charge (SoC) estimation of the energy storage component (e.g. rechargeable battery) influences the...

    Provided By Graz University of Technology

  • White Papers // Jan 2012

    Multipath-Assisted Single-Anchor Indoor Localization in an Office Environment

    Multipath propagation is one of the key problems for indoor localization systems. Strong multipath components can cause range estimates to anchor nodes to be severely biased. If a floor plan is available, reflected signal paths can be used effectively by mapping them to virtual anchors. The authors show how to...

    Provided By Graz University of Technology

  • White Papers // Jan 2012

    Sliding Window Integrator Approximations for Multichannel Autocorrelation UWB Receivers

    Non-coherent UWB receivers promise low power consumption and low processing complexity but their peak data rate is limited by the delay spread of the multipath radio channel. A recently proposed multichannel Autocorrelation Receiver (AcR) can break this rate limit because it can demodulate multicarrier signals. The hardware implementation of this...

    Provided By Graz University of Technology

  • White Papers // Jan 2012

    Analysis of Position-Related Information in Measured UWB Indoor Channels

    Conventional radio-based indoor localization systems often only make use of the direct signal path between an agent and the anchor nodes. Therefore, performance can deteriorate in non-line-of-sight situations, even though reflected multipath-components carry useful location-dependent information. Using ultra-wideband signals, these components become resolvable. Bringing together previously obtained results on the...

    Provided By Graz University of Technology

  • White Papers // Sep 2011

    Information Loss in Static Nonlinearities

    In this paper, conditional entropy is used to quantify the information loss induced by passing a continuous random variable through a memoryless nonlinear input-output system. The authors derive an expression for the information loss depending on the input density and the nonlinearity and show that the result is strongly related...

    Provided By Graz University of Technology

  • White Papers // Sep 2011

    Some Results on the Information Loss in Dynamical Systems

    In this paper, the authors investigate the information loss in (non-linear) dynamical input-output systems and provide some general results. In particular, they present an upper bound on the information loss rate, defined as the (non-negative) difference between the entropy rates of the jointly stationary stochastic processes at the input and...

    Provided By Graz University of Technology

  • White Papers // Jul 2011

    Sparse Bayesian Consensus-Based Distributed Field Estimation

    The authors present a fully decentralized algorithm that is inspired by Sparse Bayesian Learning (SBL) and can be used for non-parametric sparse estimation of unknown spatial functions - spatial fields - with Wireless Sensor Networks (WSNs). It is assumed that a spatial field is represented as a linear combination of...

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    Scatterer and Virtual Source Detection for Indoor UWB Channels

    The authors present an extension of an existing outdoor UWB scatterer detection algorithm,, making it usable for indoor scenarios. The algorithm is extended with the capability to find virtual sources, which can explain reflections from extended, plane surfaces. The extension thus removes the restriction to just single-bounce signal paths. Single-bounce...

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    Analysis of an Indoor UWB Channel for Multipath-Aided Localization

    The authors present a detailed analysis of an indoor UWB channel measurement campaign. The focus is on the modeling of the deterministic part of the multipath channel using a-priori known relevant reflections and scatterers, found from an available floor plan. Their approach uses virtual signal sources, whose locations and visibilities...

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    On the Correction of Linear Time-Varying Systems by Means of Time-Varying FIR Filters

    In this paper, methods for the design of time-varying Finite Impulse Response (FIR) filters which facilitate the correction of time-varying systems are presented. The two possible cases where an undesired time-varying system requires either preprocessing or post-processing are considered. In particular, the authors show how the methods from, can be...

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    Error Analysis and Precision Estimation for Floating-Point Dot-Products Using Affine Arithmetic

    One challenging task for VLSI and reconfigurable system design is the identification of the smallest number format possible to implement a given numerical algorithm guaranteeing some final accuracy while minimising area used, execution time and power. The authors apply affine arithmetic, an extension to interval arithmetic, to estimate the rounding...

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    Elliptic Curve Cryptography on the WISP UHF RFID Tag

    The Wireless Identification and Sensing Platform (WISP) can be used to demonstrate and evaluate new RFID applications. In this paper, the authors present practical results of an implementation of Elliptic Curve Cryptography (ECC) running on the WISP. Their implementation is based on the smallest recommended NIST elliptic curve over prime...

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    A Sliding-Windowonline Fast Variational Sparse Bayesian Learning Algorithm

    In this paper a new online learning algorithm that uses Automatic Relevance Determination (ARD) is proposed for fast adaptive nonlinear filtering. A sequential decision rule for inclusion or deletion of basic functions is obtained by applying a recently proposed fast variational Sparse Bayesian Learning (SBL) method. The proposed scheme uses...

    Provided By Graz University of Technology

  • White Papers // Apr 2011

    Practical Attacks on the Maelstrom-0 Compression Function

    In this paper the authors present attacks on the compression function of maelstrom-0. It is based on the whirlpool hash function standardized by ISO and was designed to be a faster and more robust enhancement. They analyze the compression function and use differential cryptanalysis to construct collisions for reduced variants...

    Provided By Graz University of Technology

  • White Papers // Apr 2011

    Kernel PCA for Speech Enhancement

    In this paper, the authors apply kernel Principal Component Analysis (kPCA), which has been successfully used for image denoising, to speech enhancement. In contrast to other enhancement methods which are based on the magnitude spectrum, they rather apply kPCA to complex spectral data. This is facilitated by Gaussian kernels. In...

    Provided By Graz University of Technology

  • White Papers // Mar 2011

    Bandwidth Dependence of CW Ranging to UHF RFID Tags in Severe Multipath Environments

    In this paper the impact of the signal bandwidth on the performance of Frequency Modulated Continuous Wave (FMCW) radar based ranging to Ultra High Frequency (UHF) Radio Frequency IDentification (RFID) tags is investigated. The analyses are based on Ultra-WideBand (UWB) channel measurements performed in a warehouse portal, which is a...

    Provided By Graz University of Technology

  • White Papers // Feb 2011

    Native Double Precision LINPACK Implementation on a Hybrid Reconfigurable CPU

    Applications requiring Double Precision (DP) arithmetic executed on embedded CPUs without native DP support suffer from prohibitively low performance and power efficiency. Hybrid reconfigurable CPUs, allowing for reconfiguration of the instruction set at runtime, appear as a viable computing platform for applications requiring instructions not supported by existing fixed architectures....

    Provided By Graz University of Technology

  • White Papers // Feb 2011

    Low Data Complexity Attacks on AES

    The majority of current attacks on reduced-round variants of block ciphers seeks to maximize the number of rounds that can be broken, using less data than the entire codebook and less time than exhaustive key search. In this paper, the authors pursue a different approach, restricting the data available to...

    Provided By Graz University of Technology

  • White Papers // Feb 2011

    Wideband Characterization of Backscatter Channels

    The wireless channel of backscatter radio systems is a two-way pinhole channel, created by the concatenation of two standard wireless channels. Pinhole channels cause higher attenuation and deeper fades than common wireless channels. Passive Ultra-High Frequency Radio-Frequency IDentification (UHF RFID) is such a backscatter radio system, with the backscattering tag...

    Provided By Graz University of Technology

  • White Papers // Sep 2010

    Sparse Bayesian Distributed Least-Squares Strategies for Adaptive Networks

    In this paper, the authors present a sparse distributed Recursive Least-Squares (dRLS) algorithm for adaptive sensor networks. The algorithm allows to prune weights by exploiting sparse Bayesian learning, while at the same time adding automatic regularization to improve numerical stability. With this reduction of computational complexity, the amount of energy...

    Provided By Graz University of Technology

  • White Papers // Sep 2010

    Tag-Based Sensing and Positioning in Passive UHF RFID: Tag Reflection

    The authors present a comprehensive model of the complex reflection coefficient of UHF RFID tags during modulation. The model is based on an equivalent circuit and validated using measurements of an NXP UCODE G2XMon an NXP UCODE general purpose reference antenna in an anechoic chamber. Using this model, they conduct...

    Provided By Graz University of Technology

  • White Papers // Aug 2010

    Efficient Heuristics for Discriminative Structure Learning of Bayesian Network Classifiers

    The authors introduce a simple order-based greedy heuristic for learning discriminative structure within generative Bayesian network classifiers. The authors propose two methods for establishing an order of N features. They are based on the conditional mutual information and classification rate (i.e., risk), respectively. They present results on 25 data sets...

    Provided By Graz University of Technology

  • White Papers // Jul 2010

    A Factorial Sparse Coder Model for Single Channel Source Separation

    Single Channel Source Separation (SCSS) aims to extract several source signals from a single mixture recording. Since at least two sources are interfering, the SCSS problem is ill-posed and standard source separation methods cannot be applied. Although sound sources may overlap in time, they rarely interfere in a time-frequency representation....

    Provided By Graz University of Technology

  • White Papers // Jun 2010

    UWB Channel Sounding for Ranging and Positioning in Passive UHF RFID

    The market of passive UHF RFID has reached a state where it is mainly cost-driven, although there are desired features that remain elusive. Positioning, for example, has seen a lot of research in the past years, but no conclusive breakthrough. Due to limitations enforced by tag design and regulations, such...

    Provided By Graz University of Technology

  • White Papers // Sep 2010

    Tag-Based Sensing and Positioning in Passive UHF RFID: Tag Reflection

    The authors present a comprehensive model of the complex reflection coefficient of UHF RFID tags during modulation. The model is based on an equivalent circuit and validated using measurements of an NXP UCODE G2XMon an NXP UCODE general purpose reference antenna in an anechoic chamber. Using this model, they conduct...

    Provided By Graz University of Technology

  • White Papers // Feb 2011

    Wideband Characterization of Backscatter Channels

    The wireless channel of backscatter radio systems is a two-way pinhole channel, created by the concatenation of two standard wireless channels. Pinhole channels cause higher attenuation and deeper fades than common wireless channels. Passive Ultra-High Frequency Radio-Frequency IDentification (UHF RFID) is such a backscatter radio system, with the backscattering tag...

    Provided By Graz University of Technology

  • White Papers // Nov 2012

    Signal Enhancement as Minimization of Relevant Information Loss

    The authors introduce the notion of relevant information loss for the purpose of casting the signal enhancement problem in information-theoretic terms. They show that many algorithms from machine learning can be reformulated using relevant information loss, which allows their application to the aforementioned problem. As a particular example they analyze...

    Provided By Graz University of Technology

  • White Papers // Jun 2012

    Tracking of UWB Multipath Components Using Probability Hypothesis Density Filters

    In Multipath assisted Indoor Navigation and Tracking (MINT), individual Multi-Path Components (MPCs) of the Ultra WideBand (UWB) channel needs to be extracted. A sequential Monte-Carlo based implementation of the multi-source multi-target Probability Hypothesis Density (PHD) filter is used in order to jointly estimate the number of multipath components present as...

    Provided By Graz University of Technology

  • White Papers // Jun 2012

    Beamforming Using Uniform Circular Arrays for Distant Speech Recognition in Reverberant Environments and Double-Talk Scenarios

    Beamforming is crucial for hands-free mobile terminals and voice-enabled automated home environments based on distant-speech interaction to mitigate causes of system degradation, e.g., interfering noise sources or competing speakers. This paper presents an adaptation of the most common state-of-the-art broadband beamformers to uniform circular arrays, such that competing speakers are...

    Provided By Graz University of Technology

  • White Papers // Jan 2012

    Multipath-Assisted Single-Anchor Indoor Localization in an Office Environment

    Multipath propagation is one of the key problems for indoor localization systems. Strong multipath components can cause range estimates to anchor nodes to be severely biased. If a floor plan is available, reflected signal paths can be used effectively by mapping them to virtual anchors. The authors show how to...

    Provided By Graz University of Technology

  • White Papers // Mar 2012

    Capacity and Capacity-Achieving Input Distribution of the Energy Detector

    This paper presents the capacity-achieving input distribution of an energy detection receiver structure. A proper statistical model is introduced which makes it possible to treat the energy detector as a constrained continuous communication channel. To solve this non-linear optimization the authors used the Blahut-Arimoto algorithm extended with a particle method,...

    Provided By Graz University of Technology

  • White Papers // Oct 2012

    Trading Approximation Quality Versus Sparsity Within Incremental Automatic Relevance Determination Frameworks

    In this paper a trade-off between sparsity and approximation quality of models learned with Incremental Automatic Relevance Determination (IARD) is addressed. An IARD algorithm is a class of Sparse Bayesian Learning (SBL) schemes. It permits an intuitive and simple adjustment of estimation expressions, with the adjustment having a simple interpretation...

    Provided By Graz University of Technology

  • White Papers // Jan 2012

    Analysis of Position-Related Information in Measured UWB Indoor Channels

    Conventional radio-based indoor localization systems often only make use of the direct signal path between an agent and the anchor nodes. Therefore, performance can deteriorate in non-line-of-sight situations, even though reflected multipath-components carry useful location-dependent information. Using ultra-wideband signals, these components become resolvable. Bringing together previously obtained results on the...

    Provided By Graz University of Technology

  • White Papers // Jun 2012

    Analysis of Nonideal Multipliers for Multichannel Autocorrelation UWB Receivers

    Non-coherent UWB receivers promise low power consumption and low processing complexity but their peak data rate is limited by the delay spread of the multipath radio channel. A recently proposed multichannel Autocorrelation Receiver (AcR) can break this rate limit due to its multicarrier signal demodulation capability. In this paper, the...

    Provided By Graz University of Technology

  • White Papers // Jan 2012

    Sliding Window Integrator Approximations for Multichannel Autocorrelation UWB Receivers

    Non-coherent UWB receivers promise low power consumption and low processing complexity but their peak data rate is limited by the delay spread of the multipath radio channel. A recently proposed multichannel Autocorrelation Receiver (AcR) can break this rate limit because it can demodulate multicarrier signals. The hardware implementation of this...

    Provided By Graz University of Technology

  • White Papers // Jul 2012

    Relative Information Loss in the PCA

    In this paper, the authors analyze Principle Component Analysis (PCA) as a deterministic input-output system. They show that the relative information loss induced by reducing the dimensionality of the data after performing the PCA is the same as in dimensionality reduction without PCA. Furthermore, they analyze the case where the...

    Provided By Graz University of Technology

  • White Papers // Apr 2011

    Kernel PCA for Speech Enhancement

    In this paper, the authors apply kernel Principal Component Analysis (kPCA), which has been successfully used for image denoising, to speech enhancement. In contrast to other enhancement methods which are based on the magnitude spectrum, they rather apply kPCA to complex spectral data. This is facilitated by Gaussian kernels. In...

    Provided By Graz University of Technology

  • White Papers // Jul 2011

    Sparse Bayesian Consensus-Based Distributed Field Estimation

    The authors present a fully decentralized algorithm that is inspired by Sparse Bayesian Learning (SBL) and can be used for non-parametric sparse estimation of unknown spatial functions - spatial fields - with Wireless Sensor Networks (WSNs). It is assumed that a spatial field is represented as a linear combination of...

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    Scatterer and Virtual Source Detection for Indoor UWB Channels

    The authors present an extension of an existing outdoor UWB scatterer detection algorithm,, making it usable for indoor scenarios. The algorithm is extended with the capability to find virtual sources, which can explain reflections from extended, plane surfaces. The extension thus removes the restriction to just single-bounce signal paths. Single-bounce...

    Provided By Graz University of Technology

  • White Papers // Jul 2009

    Empowering Plagiarism Detection with a Web Services Enabled Collaborative Network

    This paper explains how collaborative efforts in terms of technology and content, can help improve plagiarism detection and prevention. It presents a web service oriented architecture, which utilizes the collective strength of various search engines, context matching algorithms and indexing contributed by users. The proposed framework is an open source...

    Provided By Graz University of Technology

  • White Papers // Jul 2009

    Atmospheric Channel Effects on Terrestrial Free Space Optical Communication Links

    This paper illustrates the challenges imposed by the atmospheric channel on the design of a terrestrial laser communication link. The power loss due to scattering effect is described using the Kim/Kruse scattering model while the effect and the penalty imposed by atmospheric turbulence is highlighted by considering the Bit Error...

    Provided By Graz University of Technology

  • White Papers // Jun 2010

    A Study of Fog Characteristics Using Free-Space Optical Wireless Links

    A technique for modeling the fog droplet size distributions using modified gamma distribution has been demonstrated by considering two separate radiation fog events recorded in Graz (Austria) and Prague (Czech Republic). The measurement of Liquid Water Content (LWC) and the optical attenuations at visible wavelength are used to form equations...

    Provided By Graz University of Technology

  • White Papers // Aug 2009

    Peer Assessment System for Modern Learning Settings: Towards a Flexible e-Assessment System

    According to the rapid changes in the life styles and in order to cope with the new requirements for modern learning settings and activities, several applications have been developed to provide the modern society with these learning settings. E-assessment as a main part of e-learning has been affected by these...

    Provided By Graz University of Technology

  • White Papers // Feb 2011

    Low Data Complexity Attacks on AES

    The majority of current attacks on reduced-round variants of block ciphers seeks to maximize the number of rounds that can be broken, using less data than the entire codebook and less time than exhaustive key search. In this paper, the authors pursue a different approach, restricting the data available to...

    Provided By Graz University of Technology

  • White Papers // Sep 2009

    Efficient Quality-Based Playout Buffer Algorithm

    Playout buffers are used in VoIP systems to compensate for network delay jitter by making a trade-off between delay and loss. In this paper the authors propose a playout buffer algorithm that makes the trade-off based on maximization of conversational speech quality, aiming to keep the computational complexity lowest possible....

    Provided By Graz University of Technology

  • White Papers // Aug 2010

    Efficient Heuristics for Discriminative Structure Learning of Bayesian Network Classifiers

    The authors introduce a simple order-based greedy heuristic for learning discriminative structure within generative Bayesian network classifiers. The authors propose two methods for establishing an order of N features. They are based on the conditional mutual information and classification rate (i.e., risk), respectively. They present results on 25 data sets...

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    Elliptic Curve Cryptography on the WISP UHF RFID Tag

    The Wireless Identification and Sensing Platform (WISP) can be used to demonstrate and evaluate new RFID applications. In this paper, the authors present practical results of an implementation of Elliptic Curve Cryptography (ECC) running on the WISP. Their implementation is based on the smallest recommended NIST elliptic curve over prime...

    Provided By Graz University of Technology

  • White Papers // Sep 2009

    An Automatic Hybrid Segmentation Approach for Aligned Face Portrait Images

    With the introduction of electronic personal documents (e.g. passports) in recent years the analysis of suitable photographs has become an important field of research. Such photographs for machine readable travel documents have to fulfill a set of minimal quality requirements defined by the International Civil Aviation Organization (ICAO). As some...

    Provided By Graz University of Technology

  • White Papers // Apr 2012

    Functional Magnetic Resonance Imaging and the Challenge of Balancing Human Security with State Security

    Recent reports reveal that violent extremists are trying to obtain insider positions that may increase the impact of any attack on critical infrastructure and could potentially endanger state services, people's lives and even democracy. It is of utmost importance to be able to adopt extreme security measures in certain high-risk...

    Provided By Graz University of Technology

  • White Papers // May 2012

    Performance Bounds for Multipath-Assisted Indoor Navigation and Tracking (MINT)

    The MINT (Multipath-assisted Indoor Navigation and Tracking) problem exploits the geometry of deterministic Multi-Path Components (MPCs) for robust indoor positioning in Line-Of-Sight (LOS) and non-LOS situations. It assumes a known room layout and can thus easily make use of signals reflected by the walls, for instance. In this paper, the...

    Provided By Graz University of Technology

  • White Papers // Mar 2012

    State-of-Charge Measurement Error Simulation for Power-Aware Wireless Sensor Networks

    Wireless Sensor Networks (WSNs) are power critical systems, because they are used in application areas without wired infrastructure. Each sensor node needs a dedicated power supply. Today's protocols and applications for WSNs are often power-aware. However, the State-of-Charge (SoC) estimation of the energy storage component (e.g. rechargeable battery) influences the...

    Provided By Graz University of Technology

  • White Papers // Mar 2010

    A Mixture Maximization Approach to Multipitch Tracking With Factorial Hidden Markov Models

    The authors present a simple and efficient feature modeling approach for tracking the pitch of two speakers speaking simultaneously. They model the spectrogram features of single speakers using Gaussian mixture models in combination with the minimum description length model selection criterion. Furthermore, the MIXture MAXimization (MIXMAX) interaction model is employed...

    Provided By Graz University of Technology

  • White Papers // Sep 2009

    Experimental Characterization of System Parameters for Ranging in IEEE 802.15.4a Using Energy Detectors

    The IEEE 802.15.4a standard for Impulse Radio UltraWide Band (IR-UWB) communication systems defines a ranging scheme which relies on the measurement of the round-trip propagation time of electromagnetic pulses. Accuracy is strongly dependent on the estimation of the Time-Of-Arrival (TOA) of the pulse that is spread in time due to...

    Provided By Graz University of Technology

  • White Papers // Mar 2010

    On Discriminative Parameter Learning of Bayesian Network Classifiers

    The authors introduce three discriminative parameter learning algorithms for Bayesian network classifiers based on optimizing either the Conditional Likelihood (CL) or a lower-bound surrogate of the CL. One training procedure is based on the Extended Baum-Welch (EBW) algorithm. Similarly, the remaining two approaches iteratively optimize the parameters (initialized to ML)...

    Provided By Graz University of Technology

  • White Papers // Sep 2010

    Sparse Bayesian Distributed Least-Squares Strategies for Adaptive Networks

    In this paper, the authors present a sparse distributed Recursive Least-Squares (dRLS) algorithm for adaptive sensor networks. The algorithm allows to prune weights by exploiting sparse Bayesian learning, while at the same time adding automatic regularization to improve numerical stability. With this reduction of computational complexity, the amount of energy...

    Provided By Graz University of Technology

  • White Papers // Sep 2009

    Pathloss and Delay-Spread Analysis of Multipath Intensive Environments Using IEEE 802.15.4a UWB Signals

    In this paper, the authors present a modular IEEE 802.15.4a UWB demonstrator platform. The demonstrator supports a one-way communication link and allows for ranging and communication experiments. The proposed system can be used for hardware verification by substituting the different modules, but also to verify different receiver structures and channel...

    Provided By Graz University of Technology

  • White Papers // Mar 2011

    Bandwidth Dependence of CW Ranging to UHF RFID Tags in Severe Multipath Environments

    In this paper the impact of the signal bandwidth on the performance of Frequency Modulated Continuous Wave (FMCW) radar based ranging to Ultra High Frequency (UHF) Radio Frequency IDentification (RFID) tags is investigated. The analyses are based on Ultra-WideBand (UWB) channel measurements performed in a warehouse portal, which is a...

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    A Sliding-Windowonline Fast Variational Sparse Bayesian Learning Algorithm

    In this paper a new online learning algorithm that uses Automatic Relevance Determination (ARD) is proposed for fast adaptive nonlinear filtering. A sequential decision rule for inclusion or deletion of basic functions is obtained by applying a recently proposed fast variational Sparse Bayesian Learning (SBL) method. The proposed scheme uses...

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    On the Correction of Linear Time-Varying Systems by Means of Time-Varying FIR Filters

    In this paper, methods for the design of time-varying Finite Impulse Response (FIR) filters which facilitate the correction of time-varying systems are presented. The two possible cases where an undesired time-varying system requires either preprocessing or post-processing are considered. In particular, the authors show how the methods from, can be...

    Provided By Graz University of Technology

  • White Papers // Sep 2011

    Information Loss in Static Nonlinearities

    In this paper, conditional entropy is used to quantify the information loss induced by passing a continuous random variable through a memoryless nonlinear input-output system. The authors derive an expression for the information loss depending on the input density and the nonlinearity and show that the result is strongly related...

    Provided By Graz University of Technology

  • White Papers // Feb 2011

    Native Double Precision LINPACK Implementation on a Hybrid Reconfigurable CPU

    Applications requiring Double Precision (DP) arithmetic executed on embedded CPUs without native DP support suffer from prohibitively low performance and power efficiency. Hybrid reconfigurable CPUs, allowing for reconfiguration of the instruction set at runtime, appear as a viable computing platform for applications requiring instructions not supported by existing fixed architectures....

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    Error Analysis and Precision Estimation for Floating-Point Dot-Products Using Affine Arithmetic

    One challenging task for VLSI and reconfigurable system design is the identification of the smallest number format possible to implement a given numerical algorithm guaranteeing some final accuracy while minimising area used, execution time and power. The authors apply affine arithmetic, an extension to interval arithmetic, to estimate the rounding...

    Provided By Graz University of Technology

  • White Papers // Jun 2011

    Analysis of an Indoor UWB Channel for Multipath-Aided Localization

    The authors present a detailed analysis of an indoor UWB channel measurement campaign. The focus is on the modeling of the deterministic part of the multipath channel using a-priori known relevant reflections and scatterers, found from an available floor plan. Their approach uses virtual signal sources, whose locations and visibilities...

    Provided By Graz University of Technology