University of Bochum

Displaying 1-37 of 37 results

  • White Papers // Feb 2014

    Energy-Efficient GPGPU Architectures via Collaborative Compilation and Memristive Memory-Based Computing

    Thousands of deep and wide pipelines working concurrently make GPGPU high power consuming parts. Energy-efficiency techniques employ voltage overscaling that increases timing sensitivity to variations and hence aggravating the energy use issues. This paper proposes a method to increase spatiotemporal reuse computational effort by a combination of compilation and micro-architectural...

    Provided By University of Bochum

  • White Papers // Aug 2013

    One License to Compose Them All: A Deontic Logic Approach to Data Licensing on the Web of Data

    In the domain of linked open data a need is emerging for developing automated frameworks able to generate the licensing terms associated to data coming from heterogeneous distributed sources. This paper proposes and evaluates a deontic logic semantics which allows them to define the deontic components of the licenses, i.e.,...

    Provided By University of Bochum

  • White Papers // Jun 2013

    Predicting Your Next OLAP Query Based on Recent Analytical Sessions

    In Business Intelligence systems, users interact with data warehouses by formulating OLAP queries aimed at exploring multi-dimensional data cubes. Being able to predict the most likely next queries would provide a way to recommend interesting queries to users on the one hand, and could improve the efficiency of OLAP sessions...

    Provided By University of Bochum

  • White Papers // Jun 2013

    Trend Template: Mining Trends With a Semi-Formal Trend Model

    Predictions of uprising or falling trends are helpful in different scenarios in which users have to deal with huge amount of information in a timely manner, such as during financial analysis. This temporal aspect in various cases of data analysis requires novel data mining techniques. Assuming that a given set...

    Provided By University of Bochum

  • White Papers // Apr 2013

    A Practical Approach to Easily Monitoring and Managing IaaS Environments

    Private cloud computing has been recently pushed as a promising solution to more efficiently exploit available hardware equipment and quickly reconfigure software components depending on the current load. However, private cloud computing, and in particular the Infrastructure as a Service (IaaS) model, has been primarily adopted only by large companies,...

    Provided By University of Bochum

  • White Papers // Jan 2013

    Spectrum Leasing as an Incentive Towards Uplink Macrocell and Femtocell Cooperation

    The concept of femtocell access points underlaying existing communication infrastructure has recently emerged as a key technology that can significantly improve the coverage and performance of next-generation wireless networks. In this paper, the authors propose a framework for macrocell-femtocell cooperation under a closed access policy, in which a femtocell user...

    Provided By University of Bochum

  • White Papers // Dec 2012

    An Empirical Evaluation of Portfolios Approaches for solving CSPs

    Recent research in areas such as SAT solving and Integer Linear Programming has shown that the performances of a single arbitrarily efficient solver can be significantly outperformed by a portfolio of possibly slower on-average solvers. The authors report an empirical evaluation and comparison of portfolio approaches applied to Constraint Satisfaction...

    Provided By University of Bochum

  • White Papers // Nov 2012

    Contention Resolution Using Parametric Wavelength Converters: Performance and Cost Analysis

    This paper addresses contention resolution in optical switching fabrics exploiting Parametric Wavelength Converters (PWCs). Being a PWC able to perform simultaneous wavelength conversions, it can be employed to replace many single-channel wavelength converters, thus saving in the number of expensive optical components. Recently a switching fabric employing FixedWavelength Converters (FWCs),...

    Provided By University of Bochum

  • White Papers // Oct 2012

    Similarity Measures for OLAP Sessions

    OLAP queries are not normally formulated in isolation, but in the form of sequences called OLAP sessions. Recognizing that two OLAP sessions are similar would be useful for different applications, such as query recommendation and personalization; however, the problem of measuring OLAP session similarity has not been studied so far....

    Provided By University of Bochum

  • White Papers // Jul 2012

    A High-Throughput and Low-Latency Interconnection Network for Multi-Core Clusters With 3-D Stacked L2 Tightly-Coupled Data Memory

    The performance of most digital systems today is limited by the interconnect latency between logic and memory, rather than by the performance of logic or memory itself. Three-Dimensional (3-D) integration using Through-Silicon-Vias (TSVs) may provide a solution to overcome the scaling limitations by stacking multiple memories dies on top of...

    Provided By University of Bochum

  • White Papers // May 2012

    Context Data Distribution in Mobile Systems: A Case Study on Android-Based Phones

    Context awareness, namely the provisioning of the current execution context at the application level, forces the continuous delivery of context data to resource-constrained mobile devices, and that can become too severe a constraint even for modern support (Android, iOS, etc.). This paper focuses on the realization of a context data...

    Provided By University of Bochum

  • White Papers // May 2012

    Protograph EXIT Analysis Over Block Fading Channels With Application to Relays

    An accurate EXtrinsic Information Transfer (EXIT) analysis is developed for protograph Low-Density Parity-Check (LDPC) codes over the Block Fading Channel (BFC). The analysis is thus exploited for analyzing the behavior of distributed protograph LDPC ensembles over block fading relay channels. A novel protograph-based construction of Low-Density Parity-Check (LDPC) codes for...

    Provided By University of Bochum

  • White Papers // May 2012

    Short Non-Binary IRA Codes on Large-Girth Hamiltonian Graphs

    Short non-binary Irregular Repeat-Accumulate (IRA) codes based on well-known Hamiltonian and Hypohamiltonian graphs with large girth are presented. The mapping of the code coordinates on the graph edges is discussed for Hamiltonian graphs, and two encoding methods on Hypohamiltonian graphs are introduced. The performance of the presented codes on order-...

    Provided By University of Bochum

  • White Papers // May 2012

    The Role of Aggregate Interference on Intrinsic Network Secrecy

    Upper layer wireless security relies on the computational intractability assumption for solving certain number theoretic problems. These methods can be complemented by techniques that exploit, at the physical layer, the intrinsic properties of the wireless channel and interference. This paper considers communications with intrinsic secrecy in the presence of spatially...

    Provided By University of Bochum

  • White Papers // May 2012

    Performance Analysis of a Mesh Satellite System Based on Linear and Continuous Phase Modulations

    This paper addresses detailed waveform trade-offs for mesh satellite networks. The waveform analysis is carried out considering spectral efficiency, resilience against non linear distortion, channel impairments and interference for both linear and continuous phase modulation schemes defined in the DVBRCS2 standard. In a mesh satellite architecture two satellite terminals communicate...

    Provided By University of Bochum

  • White Papers // May 2012

    Coarse Beamforming Techniques for Multi-Beam Satellite Networks

    Coarse beamforming is a space processing scheme which allows for efficient use of the available spectral resources on the feeder link of a multi-beam broadband satellite system. In this framework, spectral occupancy of the multiplexed antenna signals that must be exchanged between the satellite and the gateway is a critical...

    Provided By University of Bochum

  • White Papers // May 2012

    Application of Contact Graph Routing to LEO Satellite DTN Communications

    Delay-/disruption-tolerant networking, which originated from research on deep space communications, has enlarged its scope to encompass all challenged networks, including LEO satellite communications. Focusing on single satellite or incomplete constellation cases, the advantages of DTN mainly relate to its ability to cope with disruption and intermittent connectivity, typical of LEOs....

    Provided By University of Bochum

  • White Papers // Mar 2012

    GPGPU-Accelerated Instruction Accurate and Fast Simulation of Thousand-Core Platforms

    Future architectures will feature hundreds to thousands of simple processors and on-chip memories connected through a network-on-chip. Architectural simulators will remain primary tools for design space exploration, performance (and power) evaluation of these massively parallel architectures. However, architectural simulation performance is a serious concern, as virtual platforms and simulation technology...

    Provided By University of Bochum

  • White Papers // Feb 2012

    Scale-Free Opportunistic Networks: Is It Possible?

    The coupling of scale-free networks with mobile unstructured networks is certainly unusual. In mobile networks, connections active at a given instant are constrained by the geographical distribution of mobile nodes, and by the limited signal strength of the wireless technology employed to build the ad-hoc overlay. This is in contrast...

    Provided By University of Bochum

  • White Papers // Jan 2012

    An Improved Two-Party Negotiation Over Continues Issues Method Secure Against Manipulatory Behavior

    This contribution focuses on two-party negotiation over continuous issues. The authors firstly prove two drawbacks of the jointly Improving Direction Method (IDM), namely that IDM is not a Strategy-Proof (SP) nor an Information Concealing (IC) method. Thus, they prove that the concurrent lack of these two properties implies the actual...

    Provided By University of Bochum

  • White Papers // Jan 2012

    On the Use of DVB-H for Satellite Multimedia Networks

    In all short-medium term business/market forecasts, the efficient provision of Digital Multimedia Broadcasting (DMB) services in mobile systems appears to be of key importance for mobile operators and broadcasters. Several DMB systems are being developed around the world, with several proposed competing standards. In this framework, the DVB (Digital Video...

    Provided By University of Bochum

  • White Papers // Dec 2011

    Cooperative Spectrum Management in Cognitive Vehicular Ad Hoc Networks

    In recent years, Cognitive Radio (CR) technology has received significant attention from the research community as it enables on-demand spectrum utilization, based on the requests of the end-users. An interesting application area of CR technology is Vehicular Ad Hoc NETworks (VANETs). In such networks, several innovative services and applications based...

    Provided By University of Bochum

  • White Papers // Dec 2011

    MAC Layer Outage Probability of Bounded Ad Hoc Networks

    The authors consider a bounded square-shaped ad hoc network scenario, within which packet arrivals are distributed randomly in space and time according to a 3-dimensional Poisson Point Process. Each packet is transmitted over a single hop to its destination, located a fixed distance away. Within this context, the outage probability...

    Provided By University of Bochum

  • White Papers // Oct 2011

    Mining Preferences from OLAP Query Logs for Proactive Personalization

    The goal of personalization is to deliver information that is relevant to an individual or a group of individuals in the most appropriate format and layout. In the OLAP context personalization is quite beneficial, because queries can be very complex and they may return huge amounts of data. Aimed at...

    Provided By University of Bochum

  • White Papers // Dec 2010

    TASTY: Tool for Automating Secure Two-PartY Computations

    Secure two-party computation allows two untrusting parties to jointly compute an arbitrary function on their respective private inputs while revealing no information beyond the outcome. Existing cryptographic compilers can automatically generate secure computation protocols from high-level specifications, but are often limited in their use and efficiency of generated protocols as...

    Provided By University of Bochum

  • White Papers // Sep 2010

    On the Performance of Moderate-Length Non-Binary LDPC Codes for Space Communications

    In this paper, an overview of recent achievements in the design and decoding of non-binary Low-Density Parity Check (LDPC) codes is provided. Non-binary constructions based on ultra-sparse matrices are compared with binary low-density parity-check codes and turbo codes from satellite communication standards, to show that larger coding gains (outperforming the...

    Provided By University of Bochum

  • White Papers // Sep 2010

    On the Capacity of Slotted Aloha Based Multi-Hop Virtual MIMO Systems

    The performance of multi-hop Virtual Multiple-Input-Multiple-Output (V-MIMO) systems, when Slotted Aloha is used to select the radio resource at each hop, is investigated. Source, destination and relaying nodes, cooperate with neighboring devices (distributed according to a Poisson Point Process) to exploit spatial diversity by means of the concept of Virtual...

    Provided By University of Bochum

  • White Papers // Aug 2010

    Norm Compliance in Business Process Modeling

    The authors investigate the concept of norm compliance in Business Process Modeling. In particular, they propose an extension of Formal Contract Logic (FCL), a combination of defeasible logic and a logic of violation, with a richer deontic language capable of capture many different facets of normative requirements. The resulting logic,...

    Provided By University of Bochum

  • White Papers // Jul 2010

    Latency Constrained Protograph-Based LDPC Convolutional Codes

    The authors propose a windowed decoding scheme for protograph-based LDPC Convolutional Codes (LDPC-CC) that allows the user to efficiently trade-off decoding performance for gains in latency. They study the performance of regular LDPC-CC with the windowed decoding scheme. In particular, they show that the class of LDPC-CC proposed in the...

    Provided By University of Bochum

  • White Papers // May 2010

    Efficiently Bounding Cardinality Ratios Through Database Constraints

    Numerical Dependencies (NDs) are a type of database constraints in which one limits the number of distinct Y -values that can appear together with any X-value, where both X and Y are sets of attributes. The seminal work by Grant and Minker has shown that NDs are not finitely axiomatizable,...

    Provided By University of Bochum

  • White Papers // Apr 2010

    A Method to Remove Deadlocks in Networks-on-Chips with Wormhole Flow Control

    Networks-on-Chip (NoCs) are a promising interconnect paradigm to address the communication bottleneck of Systems-on-Chip (SoCs). Wormhole flow control is widely used as the transmission protocol in NoCs, as it offers high throughput and low latency. To match the application characteristics, customized irregular topologies and routing functions are used. With wormhole...

    Provided By University of Bochum

  • White Papers // Apr 2010

    Sociability Based Routing for Environmental Opportunistic Networks

    Network opportunism in wireless systems aims at jointly exploiting the resources of separate networks. So far, small emphasis to this paradigm has been given in the literature related to Wireless Sensor Networks (WSNs). This paper first describes a vision on the evolution of WSNs towards the application of this concept....

    Provided By University of Bochum

  • White Papers // Dec 2009

    Windowed Erasure Decoding of LDPC Convolutional Codes

    The good performance of LDPC codes often is seen when the blocklength of the codes is large. An immediate consequence of this, especially in the context of packet-level coding wherein each codeword symbol consists of several hundreds of bits, is the associated large latency for decoding. The authors consider windowed...

    Provided By University of Bochum

  • White Papers // Jul 2009

    BPDMN: A Conservative Extension of BPMN with Enhanced Data Representation Capabilities

    The design of business processes involves the usage of modeling languages, tools and methodologies. In this paper, the authors highlight and address a relevant limitation of the Business Process Modeling Notation (BPMN): its weak data representation capabilities. In particular, they extend it with data-specific constructs derived from existing data modeling...

    Provided By University of Bochum

  • White Papers // Feb 2009

    An Algorithm for Business Process Compliance

    By business process compliance the authors mean the adherence or consistence of a set of specifications modeling a business process and a set of specifications modeling the norms for a particular business. This paper provides a novel mechanism to check whether business processes are compliant with business rules regulating them....

    Provided By University of Bochum

  • White Papers // Dec 2008

    What-if Simulation Modeling in Business Intelligence

    Optimizing decisions has become a vital factor for companies. In order to be able to evaluate beforehand the impact of a decision, managers need reliable previsional systems. Though data warehouses enable analysis of past data, they are not capable of giving anticipations of future trends. What-if analysis fills this gap...

    Provided By University of Bochum

  • White Papers // Mar 2007

    A Hardware/Software Framework for Supporting Transactional Memory in a MPSoC Environment

    Manufacturers are focusing on Multi-Processor System-on-Chip (MPSoC) architectures in order to provide increased concurrency, rather than increased clock speed, for both large-scale as well as embedded systems. Traditionally lock-based synchronization is provided to support concurrency; however, managing locks can be very difficult and error prone. In addition, the performance and...

    Provided By University of Bochum

  • White Papers // Dec 2011

    MAC Layer Outage Probability of Bounded Ad Hoc Networks

    The authors consider a bounded square-shaped ad hoc network scenario, within which packet arrivals are distributed randomly in space and time according to a 3-dimensional Poisson Point Process. Each packet is transmitted over a single hop to its destination, located a fixed distance away. Within this context, the outage probability...

    Provided By University of Bochum

  • White Papers // Apr 2010

    Sociability Based Routing for Environmental Opportunistic Networks

    Network opportunism in wireless systems aims at jointly exploiting the resources of separate networks. So far, small emphasis to this paradigm has been given in the literature related to Wireless Sensor Networks (WSNs). This paper first describes a vision on the evolution of WSNs towards the application of this concept....

    Provided By University of Bochum

  • White Papers // Nov 2012

    Contention Resolution Using Parametric Wavelength Converters: Performance and Cost Analysis

    This paper addresses contention resolution in optical switching fabrics exploiting Parametric Wavelength Converters (PWCs). Being a PWC able to perform simultaneous wavelength conversions, it can be employed to replace many single-channel wavelength converters, thus saving in the number of expensive optical components. Recently a switching fabric employing FixedWavelength Converters (FWCs),...

    Provided By University of Bochum

  • White Papers // Feb 2012

    Scale-Free Opportunistic Networks: Is It Possible?

    The coupling of scale-free networks with mobile unstructured networks is certainly unusual. In mobile networks, connections active at a given instant are constrained by the geographical distribution of mobile nodes, and by the limited signal strength of the wireless technology employed to build the ad-hoc overlay. This is in contrast...

    Provided By University of Bochum

  • White Papers // Jan 2013

    Spectrum Leasing as an Incentive Towards Uplink Macrocell and Femtocell Cooperation

    The concept of femtocell access points underlaying existing communication infrastructure has recently emerged as a key technology that can significantly improve the coverage and performance of next-generation wireless networks. In this paper, the authors propose a framework for macrocell-femtocell cooperation under a closed access policy, in which a femtocell user...

    Provided By University of Bochum

  • White Papers // Jul 2010

    Latency Constrained Protograph-Based LDPC Convolutional Codes

    The authors propose a windowed decoding scheme for protograph-based LDPC Convolutional Codes (LDPC-CC) that allows the user to efficiently trade-off decoding performance for gains in latency. They study the performance of regular LDPC-CC with the windowed decoding scheme. In particular, they show that the class of LDPC-CC proposed in the...

    Provided By University of Bochum

  • White Papers // Jun 2013

    Predicting Your Next OLAP Query Based on Recent Analytical Sessions

    In Business Intelligence systems, users interact with data warehouses by formulating OLAP queries aimed at exploring multi-dimensional data cubes. Being able to predict the most likely next queries would provide a way to recommend interesting queries to users on the one hand, and could improve the efficiency of OLAP sessions...

    Provided By University of Bochum

  • White Papers // Mar 2012

    GPGPU-Accelerated Instruction Accurate and Fast Simulation of Thousand-Core Platforms

    Future architectures will feature hundreds to thousands of simple processors and on-chip memories connected through a network-on-chip. Architectural simulators will remain primary tools for design space exploration, performance (and power) evaluation of these massively parallel architectures. However, architectural simulation performance is a serious concern, as virtual platforms and simulation technology...

    Provided By University of Bochum

  • White Papers // Apr 2010

    A Method to Remove Deadlocks in Networks-on-Chips with Wormhole Flow Control

    Networks-on-Chip (NoCs) are a promising interconnect paradigm to address the communication bottleneck of Systems-on-Chip (SoCs). Wormhole flow control is widely used as the transmission protocol in NoCs, as it offers high throughput and low latency. To match the application characteristics, customized irregular topologies and routing functions are used. With wormhole...

    Provided By University of Bochum

  • White Papers // Jul 2012

    A High-Throughput and Low-Latency Interconnection Network for Multi-Core Clusters With 3-D Stacked L2 Tightly-Coupled Data Memory

    The performance of most digital systems today is limited by the interconnect latency between logic and memory, rather than by the performance of logic or memory itself. Three-Dimensional (3-D) integration using Through-Silicon-Vias (TSVs) may provide a solution to overcome the scaling limitations by stacking multiple memories dies on top of...

    Provided By University of Bochum

  • White Papers // Aug 2013

    One License to Compose Them All: A Deontic Logic Approach to Data Licensing on the Web of Data

    In the domain of linked open data a need is emerging for developing automated frameworks able to generate the licensing terms associated to data coming from heterogeneous distributed sources. This paper proposes and evaluates a deontic logic semantics which allows them to define the deontic components of the licenses, i.e.,...

    Provided By University of Bochum

  • White Papers // Mar 2007

    A Hardware/Software Framework for Supporting Transactional Memory in a MPSoC Environment

    Manufacturers are focusing on Multi-Processor System-on-Chip (MPSoC) architectures in order to provide increased concurrency, rather than increased clock speed, for both large-scale as well as embedded systems. Traditionally lock-based synchronization is provided to support concurrency; however, managing locks can be very difficult and error prone. In addition, the performance and...

    Provided By University of Bochum

  • White Papers // Feb 2014

    Energy-Efficient GPGPU Architectures via Collaborative Compilation and Memristive Memory-Based Computing

    Thousands of deep and wide pipelines working concurrently make GPGPU high power consuming parts. Energy-efficiency techniques employ voltage overscaling that increases timing sensitivity to variations and hence aggravating the energy use issues. This paper proposes a method to increase spatiotemporal reuse computational effort by a combination of compilation and micro-architectural...

    Provided By University of Bochum

  • White Papers // Dec 2010

    TASTY: Tool for Automating Secure Two-PartY Computations

    Secure two-party computation allows two untrusting parties to jointly compute an arbitrary function on their respective private inputs while revealing no information beyond the outcome. Existing cryptographic compilers can automatically generate secure computation protocols from high-level specifications, but are often limited in their use and efficiency of generated protocols as...

    Provided By University of Bochum

  • White Papers // Dec 2011

    Cooperative Spectrum Management in Cognitive Vehicular Ad Hoc Networks

    In recent years, Cognitive Radio (CR) technology has received significant attention from the research community as it enables on-demand spectrum utilization, based on the requests of the end-users. An interesting application area of CR technology is Vehicular Ad Hoc NETworks (VANETs). In such networks, several innovative services and applications based...

    Provided By University of Bochum

  • White Papers // Sep 2010

    On the Capacity of Slotted Aloha Based Multi-Hop Virtual MIMO Systems

    The performance of multi-hop Virtual Multiple-Input-Multiple-Output (V-MIMO) systems, when Slotted Aloha is used to select the radio resource at each hop, is investigated. Source, destination and relaying nodes, cooperate with neighboring devices (distributed according to a Poisson Point Process) to exploit spatial diversity by means of the concept of Virtual...

    Provided By University of Bochum

  • White Papers // Sep 2010

    On the Performance of Moderate-Length Non-Binary LDPC Codes for Space Communications

    In this paper, an overview of recent achievements in the design and decoding of non-binary Low-Density Parity Check (LDPC) codes is provided. Non-binary constructions based on ultra-sparse matrices are compared with binary low-density parity-check codes and turbo codes from satellite communication standards, to show that larger coding gains (outperforming the...

    Provided By University of Bochum

  • White Papers // Dec 2009

    Windowed Erasure Decoding of LDPC Convolutional Codes

    The good performance of LDPC codes often is seen when the blocklength of the codes is large. An immediate consequence of this, especially in the context of packet-level coding wherein each codeword symbol consists of several hundreds of bits, is the associated large latency for decoding. The authors consider windowed...

    Provided By University of Bochum

  • White Papers // Apr 2013

    A Practical Approach to Easily Monitoring and Managing IaaS Environments

    Private cloud computing has been recently pushed as a promising solution to more efficiently exploit available hardware equipment and quickly reconfigure software components depending on the current load. However, private cloud computing, and in particular the Infrastructure as a Service (IaaS) model, has been primarily adopted only by large companies,...

    Provided By University of Bochum

  • White Papers // Jul 2009

    BPDMN: A Conservative Extension of BPMN with Enhanced Data Representation Capabilities

    The design of business processes involves the usage of modeling languages, tools and methodologies. In this paper, the authors highlight and address a relevant limitation of the Business Process Modeling Notation (BPMN): its weak data representation capabilities. In particular, they extend it with data-specific constructs derived from existing data modeling...

    Provided By University of Bochum

  • White Papers // Dec 2008

    What-if Simulation Modeling in Business Intelligence

    Optimizing decisions has become a vital factor for companies. In order to be able to evaluate beforehand the impact of a decision, managers need reliable previsional systems. Though data warehouses enable analysis of past data, they are not capable of giving anticipations of future trends. What-if analysis fills this gap...

    Provided By University of Bochum

  • White Papers // Aug 2010

    Norm Compliance in Business Process Modeling

    The authors investigate the concept of norm compliance in Business Process Modeling. In particular, they propose an extension of Formal Contract Logic (FCL), a combination of defeasible logic and a logic of violation, with a richer deontic language capable of capture many different facets of normative requirements. The resulting logic,...

    Provided By University of Bochum

  • White Papers // Feb 2009

    An Algorithm for Business Process Compliance

    By business process compliance the authors mean the adherence or consistence of a set of specifications modeling a business process and a set of specifications modeling the norms for a particular business. This paper provides a novel mechanism to check whether business processes are compliant with business rules regulating them....

    Provided By University of Bochum

  • White Papers // Jun 2013

    Trend Template: Mining Trends With a Semi-Formal Trend Model

    Predictions of uprising or falling trends are helpful in different scenarios in which users have to deal with huge amount of information in a timely manner, such as during financial analysis. This temporal aspect in various cases of data analysis requires novel data mining techniques. Assuming that a given set...

    Provided By University of Bochum

  • White Papers // Oct 2012

    Similarity Measures for OLAP Sessions

    OLAP queries are not normally formulated in isolation, but in the form of sequences called OLAP sessions. Recognizing that two OLAP sessions are similar would be useful for different applications, such as query recommendation and personalization; however, the problem of measuring OLAP session similarity has not been studied so far....

    Provided By University of Bochum

  • White Papers // Oct 2011

    Mining Preferences from OLAP Query Logs for Proactive Personalization

    The goal of personalization is to deliver information that is relevant to an individual or a group of individuals in the most appropriate format and layout. In the OLAP context personalization is quite beneficial, because queries can be very complex and they may return huge amounts of data. Aimed at...

    Provided By University of Bochum

  • White Papers // Jan 2012

    An Improved Two-Party Negotiation Over Continues Issues Method Secure Against Manipulatory Behavior

    This contribution focuses on two-party negotiation over continuous issues. The authors firstly prove two drawbacks of the jointly Improving Direction Method (IDM), namely that IDM is not a Strategy-Proof (SP) nor an Information Concealing (IC) method. Thus, they prove that the concurrent lack of these two properties implies the actual...

    Provided By University of Bochum

  • White Papers // May 2012

    Context Data Distribution in Mobile Systems: A Case Study on Android-Based Phones

    Context awareness, namely the provisioning of the current execution context at the application level, forces the continuous delivery of context data to resource-constrained mobile devices, and that can become too severe a constraint even for modern support (Android, iOS, etc.). This paper focuses on the realization of a context data...

    Provided By University of Bochum

  • White Papers // May 2012

    Protograph EXIT Analysis Over Block Fading Channels With Application to Relays

    An accurate EXtrinsic Information Transfer (EXIT) analysis is developed for protograph Low-Density Parity-Check (LDPC) codes over the Block Fading Channel (BFC). The analysis is thus exploited for analyzing the behavior of distributed protograph LDPC ensembles over block fading relay channels. A novel protograph-based construction of Low-Density Parity-Check (LDPC) codes for...

    Provided By University of Bochum

  • White Papers // May 2012

    Short Non-Binary IRA Codes on Large-Girth Hamiltonian Graphs

    Short non-binary Irregular Repeat-Accumulate (IRA) codes based on well-known Hamiltonian and Hypohamiltonian graphs with large girth are presented. The mapping of the code coordinates on the graph edges is discussed for Hamiltonian graphs, and two encoding methods on Hypohamiltonian graphs are introduced. The performance of the presented codes on order-...

    Provided By University of Bochum

  • White Papers // May 2012

    The Role of Aggregate Interference on Intrinsic Network Secrecy

    Upper layer wireless security relies on the computational intractability assumption for solving certain number theoretic problems. These methods can be complemented by techniques that exploit, at the physical layer, the intrinsic properties of the wireless channel and interference. This paper considers communications with intrinsic secrecy in the presence of spatially...

    Provided By University of Bochum

  • White Papers // May 2012

    Performance Analysis of a Mesh Satellite System Based on Linear and Continuous Phase Modulations

    This paper addresses detailed waveform trade-offs for mesh satellite networks. The waveform analysis is carried out considering spectral efficiency, resilience against non linear distortion, channel impairments and interference for both linear and continuous phase modulation schemes defined in the DVBRCS2 standard. In a mesh satellite architecture two satellite terminals communicate...

    Provided By University of Bochum

  • White Papers // May 2012

    Coarse Beamforming Techniques for Multi-Beam Satellite Networks

    Coarse beamforming is a space processing scheme which allows for efficient use of the available spectral resources on the feeder link of a multi-beam broadband satellite system. In this framework, spectral occupancy of the multiplexed antenna signals that must be exchanged between the satellite and the gateway is a critical...

    Provided By University of Bochum

  • White Papers // May 2012

    Application of Contact Graph Routing to LEO Satellite DTN Communications

    Delay-/disruption-tolerant networking, which originated from research on deep space communications, has enlarged its scope to encompass all challenged networks, including LEO satellite communications. Focusing on single satellite or incomplete constellation cases, the advantages of DTN mainly relate to its ability to cope with disruption and intermittent connectivity, typical of LEOs....

    Provided By University of Bochum

  • White Papers // Jan 2012

    On the Use of DVB-H for Satellite Multimedia Networks

    In all short-medium term business/market forecasts, the efficient provision of Digital Multimedia Broadcasting (DMB) services in mobile systems appears to be of key importance for mobile operators and broadcasters. Several DMB systems are being developed around the world, with several proposed competing standards. In this framework, the DVB (Digital Video...

    Provided By University of Bochum

  • White Papers // Dec 2012

    An Empirical Evaluation of Portfolios Approaches for solving CSPs

    Recent research in areas such as SAT solving and Integer Linear Programming has shown that the performances of a single arbitrarily efficient solver can be significantly outperformed by a portfolio of possibly slower on-average solvers. The authors report an empirical evaluation and comparison of portfolio approaches applied to Constraint Satisfaction...

    Provided By University of Bochum

  • White Papers // May 2010

    Efficiently Bounding Cardinality Ratios Through Database Constraints

    Numerical Dependencies (NDs) are a type of database constraints in which one limits the number of distinct Y -values that can appear together with any X-value, where both X and Y are sets of attributes. The seminal work by Grant and Minker has shown that NDs are not finitely axiomatizable,...

    Provided By University of Bochum