Humboldt University Berlin

Displaying 1-27 of 27 results

  • White Papers // Apr 2012

    Measurement-Based Interference Modeling Using Channel Occupancy in Wireless Mesh Networks

    The authors introduce a linear measurement-based method for interference estimation in wireless mesh networks. The approach is based on measuring the channel occupancy and requires only O(n) measurements for a network with n nodes, thus making it suitable for large network deployments. They show, how they utilize the carrier sensing...

    Provided By Humboldt University Berlin

  • White Papers // Mar 2012

    A Low-Cost MIMO Mesh Testbed Based on 802.11n

    In this paper, the authors present a configurable and inexpensive MIMO mesh network research platform based on IEEE 802.11n and open source software. There are two requirements for such a research test-bed. First configurability: the researcher needs the ability to modify hard- and software on each ISO/OSI layer. Secondly, the...

    Provided By Humboldt University Berlin

  • White Papers // Mar 2012

    Towards MAC/Anycast Diversity in IEEE 802.11n MIMO Networks

    Opportunistic Routing (OR) is a novel routing technique for wireless mesh networks that exploits the broadcast nature of the wireless medium. OR combines frames from multiple receivers and therefore creates a form of Spatial Diversity, called MAC Diversity. The gain from OR is especially high in networks where the majority...

    Provided By Humboldt University Berlin

  • White Papers // Feb 2012

    On Frequency-Selective Scheduling in SDMA-OFDMA Systems

    Orthogonal Frequency Division Multiple Access (OFDMA) is a multi-user version of the Orthogonal Frequency Division Multiplexing (OFDM) transmission technique, which divides a wideband channel into a number of orthogonal narrowband subchannels, called subcarriers. An OFDMA system takes advantage of both Frequency Diversity (FD) gain and Frequency-Selective Scheduling (FSS) gain. A...

    Provided By Humboldt University Berlin

  • White Papers // Jan 2012

    SGSA: An SDFMA-OFDMA Scheduling Solution

    Future wireless networks need to address the predicted growth in mobile traffic volume, expected to have an explosive growth in the next five years mainly driven by video and web applications. Transmission schemes based on Orthogonal Frequency Division Multiple Access (OFDMA) combined with Space Division Multiple Access (SDMA) techniques are...

    Provided By Humboldt University Berlin

  • White Papers // Oct 2011

    DES-Chan: A Framework for Distributed Channel Assignment in Wireless Mesh Networks

    In this paper, the authors present the DES-Chan framework for experimentally-driven research on distributed channel assignment algorithms in wireless mesh networks. The implementation process of channel assignment algorithms is a difficult task for the researcher since common operating systems do not support channel assignment algorithms out of the box. DES-Chan...

    Provided By Humboldt University Berlin

  • White Papers // Oct 2011

    Experiences From the MANIAC Challenge

    The MANIAC Challenge is a competition for cooperation strategies in wireless ad-hoc networks with the focus on experimental evaluation. The authors present the results of the MANIAC Challenge and discuss characteristics of real networks such as link instability and mobility, which are often simplified in common network simulators. They introduce...

    Provided By Humboldt University Berlin

  • White Papers // Sep 2011

    Reinvestigating Channel Orthogonality - Adjacent Channel Interference in IEEE 802.11n Networks

    In this paper, the authors analyze the adverse effects of Adjacent Channel Interference (ACI) on 802.11 with a focus on new 802.11n standard. ACI is causing problems that are related to the carrier sensing mechanism in 802.11. On the one hand, the carrier sensing is sometimes too restrictive thus preventing...

    Provided By Humboldt University Berlin

  • White Papers // Aug 2011

    ClickWatch - An Experimentation Framework for Communication Network Test-Beds

    It is hard to experiment with test-beds for communication networks: data produced in the network has to be retrieved and analyzed, networks must be reconfigured before and between experiments, data is often little structured (log-files) and analysis methods and tools are generic. Even though many problems of experimentation are the...

    Provided By Humboldt University Berlin

  • White Papers // Aug 2011

    Evaluation of a Low-Cost IEEE 802.11n MIMO Testbed

    This paper presents and evaluates a configurable and inexpensive MIMO mesh network platform based on IEEE 802.11n and open source software for research purposes. The requirements on such a research testbed are twofold. On the one hand a highly configurable solution is desirable where the researcher is able to make...

    Provided By Humboldt University Berlin

  • White Papers // Jun 2011

    An Experts' Perspective on Enterprise Architecture Goals, Framework Adoption and Benefit Assessment

    In recent years, Enterprise Architecture (EA) management has become an intensively discussed approach in both industry and academia for managing the complexity of an enterprise from a holistic perspective. While there is a strong academic and practical interest in EA frameworks and EA modeling, there is a notable insecurity about...

    Provided By Humboldt University Berlin

  • White Papers // Mar 2011

    On Interrelations Of Recurrences And Connectivity Trends Between Stock Indices

    Financial data has been extensively studied for correlations using Pearson's cross-correlation coefficient ? as the point of departure. The authors employ an estimator based on recurrence plots - the Correlation of Probability of Recurrence (CPR) - to analyze connections between nine stock indices spread worldwide. They suggest a slight modification...

    Provided By Humboldt University Berlin

  • White Papers // Jan 2011

    Highly Available Location-Based Services in Mobile Environments

    The authors show how to use Web Services standards for propagation, discovery, and composition of location-based services in mobile environments. To achieve semantic interoperability the authors express location information in XML using context-specific ontologies. The achieved interoperability allows for context-aware on-demand service composition making the composite service highly available and...

    Provided By Humboldt University Berlin

  • White Papers // Apr 2010

    Availability of Data in Locality-Aware Unreliable Networks

    The goal of the authors' paper is to improve data availability in large-scale wireless networks in a disaster scenario, where spatially correlated group of nodes may fail. In this paper, they analytically evaluate the efficacy of existing replication schemes from structured overlay networks under relaxed system constraints. The analysis shows...

    Provided By Humboldt University Berlin

  • White Papers // Mar 2010

    Distortions In A Multi-level Co-financing System: The Case Of The Agri-environmental Programme Of Saxony-Anhalt

    In this paper, the authors analyze the impact of the EU multi-level co-financing system on regional policy-making and priority setting taking the case of the agri-environmental programme of Saxony-Anhalt. The implications of several co-financing scenarios are analyzed and compared to respective lump-sum transfers using an interactive linear programming approach. The...

    Provided By Humboldt University Berlin

  • White Papers // Feb 2010

    Innovation Contests With Entry Auction

    The authors consider procurement of an innovation from heterogeneous sellers. Innovations are random but depend on unobservable effort and private information. They compare two procurement mechanisms where potential sellers first bid in an auction for admission to an innovation contest. After the contest, an innovation is procured employing either a...

    Provided By Humboldt University Berlin

  • White Papers // Jan 2010

    Optimal Procurement Contracts With Pre-Project Planning

    The paper studies procurement contracts with pre - project investigations in the presence of adverse selection and moral hazard. To model the procurer's problem, the authors extend a standard sequential screening model to endogenous information acquisition with moral hazard. The optimal contract displays systematic distortions in information acquisition. Due to...

    Provided By Humboldt University Berlin

  • White Papers // Jan 2010

    Market Share Dynamics In A Model With Search And Word-of-mouth Communication

    This paper analyzes price competition in an infinitely repeated duopoly game. In each period, consumers remember the existence and location of their previous supplier. New information is gathered via search or word-of-mouth communication. Market outcomes are history-dependent, and the Markov perfection refinement is used to narrow the set of equilibria....

    Provided By Humboldt University Berlin

  • White Papers // Nov 2009

    Competition Policy Trends And Economic Growth: Cross-National Empirical Evidence

    Motivated by the general lack of empirical scholarship concerning the cross-national environment for competition policy, the author presents measures here of the overall resources dedicated to competition policy and the merger policy workload for thirty-two antitrust jurisdictions over the 1992-2007 period. The data allow analysing a number of perceived trends...

    Provided By Humboldt University Berlin

  • White Papers // Oct 2009

    Competition Policy And Productivity Growth: An Empirical Assessment

    This paper empirically investigates the effectiveness of competition policy by estimating its impact on Total Factor Productivity (TFP) growth for 22 industries in 12 OECD countries over the period 1995-2005. The authors find a robust positive and significant effect of competition policy as measured by newly created indexes. They provide...

    Provided By Humboldt University Berlin

  • White Papers // Aug 2009

    Intelligent Scientific Authoring Tools: Interactive Data Mining for Constructive Uses of Citation Networks

    Many powerful methods and tools exist for extracting meaning from scientific publications, their texts, and their citation links. However, existing proposals often neglect a fundamental aspect of learning: that understanding and learning require an active and constructive exploration of a domain. In this paper, the authors describe a new method...

    Provided By Humboldt University Berlin

  • White Papers // Aug 2009

    Greedy Scheduling Algorithm (GSA): Design and Evaluation of an Efficient and Flexible WiMAX OFDMA Scheduling Solution

    WiMAX is one of the most promising technologies to provide broadband wireless access in the near future. In this paper, the authors focus on the study of the combined performance of a WiMAX Base Station MAC downlink scheduler and OFDMA packing algorithm which mainly determine the usage efficiency of the...

    Provided By Humboldt University Berlin

  • White Papers // Jul 2009

    About the GSM-Dm-Channels

    Development of ISDN was prerequisite to the development of GSM, not only from a technological point of view, but also because of the amount of thought required to work out the signaling between a telephone station and a network. As you can read in the 'How To' section of this...

    Provided By Humboldt University Berlin

  • White Papers // Apr 2009

    Cross-Core Event Monitoring for Processor Failure Prediction

    A recent trend in the design of commodity processors is the combination of multiple independent execution units on one chip. With the resulting increase of complexity and transistor count, it becomes more and more likely that a single execution unit on a processor gets faulty. In order to tackle this...

    Provided By Humboldt University Berlin

  • White Papers // Apr 2009

    Results On Numerics For FBSDE With Drivers Of Quadratic Growth

    The authors consider the problem of numerical approximation for Forward-Backward Stochastic Differential Equations with drivers of quadratic growth (qgFBSDE). To illustrate the significance of qgFBSDE, they discuss a problem of cross hedging of an insurance related financial derivative using correlated assets. For the convergence of numerical approximation schemes for such...

    Provided By Humboldt University Berlin

  • White Papers // Sep 2007

    A Feature-Complete Petri Net Semantics for WS-BPEL 2.0 and Its Compiler BPEL2oWFN

    Recently, the emerging standard to describe business processes on top of Web service technology, the Web Service Business Execution Language (WS-BPEL), has been officially specified. The authors present an extension of a Petri net semantics for the Web Service Business Execution Language (WS-BPEL). This extension covers the novel activities and...

    Provided By Humboldt University Berlin

  • White Papers // Jul 2003

    The Duality of Option Investment Strategies for Hedge Funds

    This paper studies the structure of optimal investment strategies for a hedge fund manager, who is typically the general partner and thus a major investor in the fund, using stock index options in the hedge fund's portfolio in a discrete-time framework that overcomes some of the drawbacks of the continuous-time...

    Provided By Humboldt University Berlin

  • White Papers // Oct 2011

    DES-Chan: A Framework for Distributed Channel Assignment in Wireless Mesh Networks

    In this paper, the authors present the DES-Chan framework for experimentally-driven research on distributed channel assignment algorithms in wireless mesh networks. The implementation process of channel assignment algorithms is a difficult task for the researcher since common operating systems do not support channel assignment algorithms out of the box. DES-Chan...

    Provided By Humboldt University Berlin

  • White Papers // Apr 2012

    Measurement-Based Interference Modeling Using Channel Occupancy in Wireless Mesh Networks

    The authors introduce a linear measurement-based method for interference estimation in wireless mesh networks. The approach is based on measuring the channel occupancy and requires only O(n) measurements for a network with n nodes, thus making it suitable for large network deployments. They show, how they utilize the carrier sensing...

    Provided By Humboldt University Berlin

  • White Papers // Oct 2011

    Experiences From the MANIAC Challenge

    The MANIAC Challenge is a competition for cooperation strategies in wireless ad-hoc networks with the focus on experimental evaluation. The authors present the results of the MANIAC Challenge and discuss characteristics of real networks such as link instability and mobility, which are often simplified in common network simulators. They introduce...

    Provided By Humboldt University Berlin

  • White Papers // Jun 2011

    An Experts' Perspective on Enterprise Architecture Goals, Framework Adoption and Benefit Assessment

    In recent years, Enterprise Architecture (EA) management has become an intensively discussed approach in both industry and academia for managing the complexity of an enterprise from a holistic perspective. While there is a strong academic and practical interest in EA frameworks and EA modeling, there is a notable insecurity about...

    Provided By Humboldt University Berlin

  • White Papers // Jul 2009

    About the GSM-Dm-Channels

    Development of ISDN was prerequisite to the development of GSM, not only from a technological point of view, but also because of the amount of thought required to work out the signaling between a telephone station and a network. As you can read in the 'How To' section of this...

    Provided By Humboldt University Berlin

  • White Papers // Jan 2011

    Highly Available Location-Based Services in Mobile Environments

    The authors show how to use Web Services standards for propagation, discovery, and composition of location-based services in mobile environments. To achieve semantic interoperability the authors express location information in XML using context-specific ontologies. The achieved interoperability allows for context-aware on-demand service composition making the composite service highly available and...

    Provided By Humboldt University Berlin

  • White Papers // Jan 2010

    Optimal Procurement Contracts With Pre-Project Planning

    The paper studies procurement contracts with pre - project investigations in the presence of adverse selection and moral hazard. To model the procurer's problem, the authors extend a standard sequential screening model to endogenous information acquisition with moral hazard. The optimal contract displays systematic distortions in information acquisition. Due to...

    Provided By Humboldt University Berlin

  • White Papers // Feb 2010

    Innovation Contests With Entry Auction

    The authors consider procurement of an innovation from heterogeneous sellers. Innovations are random but depend on unobservable effort and private information. They compare two procurement mechanisms where potential sellers first bid in an auction for admission to an innovation contest. After the contest, an innovation is procured employing either a...

    Provided By Humboldt University Berlin

  • White Papers // Oct 2009

    Competition Policy And Productivity Growth: An Empirical Assessment

    This paper empirically investigates the effectiveness of competition policy by estimating its impact on Total Factor Productivity (TFP) growth for 22 industries in 12 OECD countries over the period 1995-2005. The authors find a robust positive and significant effect of competition policy as measured by newly created indexes. They provide...

    Provided By Humboldt University Berlin

  • White Papers // Aug 2009

    Intelligent Scientific Authoring Tools: Interactive Data Mining for Constructive Uses of Citation Networks

    Many powerful methods and tools exist for extracting meaning from scientific publications, their texts, and their citation links. However, existing proposals often neglect a fundamental aspect of learning: that understanding and learning require an active and constructive exploration of a domain. In this paper, the authors describe a new method...

    Provided By Humboldt University Berlin

  • White Papers // Mar 2011

    On Interrelations Of Recurrences And Connectivity Trends Between Stock Indices

    Financial data has been extensively studied for correlations using Pearson's cross-correlation coefficient ? as the point of departure. The authors employ an estimator based on recurrence plots - the Correlation of Probability of Recurrence (CPR) - to analyze connections between nine stock indices spread worldwide. They suggest a slight modification...

    Provided By Humboldt University Berlin

  • White Papers // Apr 2009

    Results On Numerics For FBSDE With Drivers Of Quadratic Growth

    The authors consider the problem of numerical approximation for Forward-Backward Stochastic Differential Equations with drivers of quadratic growth (qgFBSDE). To illustrate the significance of qgFBSDE, they discuss a problem of cross hedging of an insurance related financial derivative using correlated assets. For the convergence of numerical approximation schemes for such...

    Provided By Humboldt University Berlin

  • White Papers // Nov 2009

    Competition Policy Trends And Economic Growth: Cross-National Empirical Evidence

    Motivated by the general lack of empirical scholarship concerning the cross-national environment for competition policy, the author presents measures here of the overall resources dedicated to competition policy and the merger policy workload for thirty-two antitrust jurisdictions over the 1992-2007 period. The data allow analysing a number of perceived trends...

    Provided By Humboldt University Berlin

  • White Papers // Mar 2010

    Distortions In A Multi-level Co-financing System: The Case Of The Agri-environmental Programme Of Saxony-Anhalt

    In this paper, the authors analyze the impact of the EU multi-level co-financing system on regional policy-making and priority setting taking the case of the agri-environmental programme of Saxony-Anhalt. The implications of several co-financing scenarios are analyzed and compared to respective lump-sum transfers using an interactive linear programming approach. The...

    Provided By Humboldt University Berlin

  • White Papers // Jan 2010

    Market Share Dynamics In A Model With Search And Word-of-mouth Communication

    This paper analyzes price competition in an infinitely repeated duopoly game. In each period, consumers remember the existence and location of their previous supplier. New information is gathered via search or word-of-mouth communication. Market outcomes are history-dependent, and the Markov perfection refinement is used to narrow the set of equilibria....

    Provided By Humboldt University Berlin

  • White Papers // Sep 2011

    Reinvestigating Channel Orthogonality - Adjacent Channel Interference in IEEE 802.11n Networks

    In this paper, the authors analyze the adverse effects of Adjacent Channel Interference (ACI) on 802.11 with a focus on new 802.11n standard. ACI is causing problems that are related to the carrier sensing mechanism in 802.11. On the one hand, the carrier sensing is sometimes too restrictive thus preventing...

    Provided By Humboldt University Berlin

  • White Papers // Aug 2011

    ClickWatch - An Experimentation Framework for Communication Network Test-Beds

    It is hard to experiment with test-beds for communication networks: data produced in the network has to be retrieved and analyzed, networks must be reconfigured before and between experiments, data is often little structured (log-files) and analysis methods and tools are generic. Even though many problems of experimentation are the...

    Provided By Humboldt University Berlin

  • White Papers // Aug 2011

    Evaluation of a Low-Cost IEEE 802.11n MIMO Testbed

    This paper presents and evaluates a configurable and inexpensive MIMO mesh network platform based on IEEE 802.11n and open source software for research purposes. The requirements on such a research testbed are twofold. On the one hand a highly configurable solution is desirable where the researcher is able to make...

    Provided By Humboldt University Berlin

  • White Papers // Aug 2009

    Greedy Scheduling Algorithm (GSA): Design and Evaluation of an Efficient and Flexible WiMAX OFDMA Scheduling Solution

    WiMAX is one of the most promising technologies to provide broadband wireless access in the near future. In this paper, the authors focus on the study of the combined performance of a WiMAX Base Station MAC downlink scheduler and OFDMA packing algorithm which mainly determine the usage efficiency of the...

    Provided By Humboldt University Berlin

  • White Papers // Apr 2010

    Availability of Data in Locality-Aware Unreliable Networks

    The goal of the authors' paper is to improve data availability in large-scale wireless networks in a disaster scenario, where spatially correlated group of nodes may fail. In this paper, they analytically evaluate the efficacy of existing replication schemes from structured overlay networks under relaxed system constraints. The analysis shows...

    Provided By Humboldt University Berlin

  • White Papers // Feb 2012

    On Frequency-Selective Scheduling in SDMA-OFDMA Systems

    Orthogonal Frequency Division Multiple Access (OFDMA) is a multi-user version of the Orthogonal Frequency Division Multiplexing (OFDM) transmission technique, which divides a wideband channel into a number of orthogonal narrowband subchannels, called subcarriers. An OFDMA system takes advantage of both Frequency Diversity (FD) gain and Frequency-Selective Scheduling (FSS) gain. A...

    Provided By Humboldt University Berlin

  • White Papers // Mar 2012

    Towards MAC/Anycast Diversity in IEEE 802.11n MIMO Networks

    Opportunistic Routing (OR) is a novel routing technique for wireless mesh networks that exploits the broadcast nature of the wireless medium. OR combines frames from multiple receivers and therefore creates a form of Spatial Diversity, called MAC Diversity. The gain from OR is especially high in networks where the majority...

    Provided By Humboldt University Berlin

  • White Papers // Jan 2012

    SGSA: An SDFMA-OFDMA Scheduling Solution

    Future wireless networks need to address the predicted growth in mobile traffic volume, expected to have an explosive growth in the next five years mainly driven by video and web applications. Transmission schemes based on Orthogonal Frequency Division Multiple Access (OFDMA) combined with Space Division Multiple Access (SDMA) techniques are...

    Provided By Humboldt University Berlin

  • White Papers // Mar 2012

    A Low-Cost MIMO Mesh Testbed Based on 802.11n

    In this paper, the authors present a configurable and inexpensive MIMO mesh network research platform based on IEEE 802.11n and open source software. There are two requirements for such a research test-bed. First configurability: the researcher needs the ability to modify hard- and software on each ISO/OSI layer. Secondly, the...

    Provided By Humboldt University Berlin

  • White Papers // Apr 2009

    Cross-Core Event Monitoring for Processor Failure Prediction

    A recent trend in the design of commodity processors is the combination of multiple independent execution units on one chip. With the resulting increase of complexity and transistor count, it becomes more and more likely that a single execution unit on a processor gets faulty. In order to tackle this...

    Provided By Humboldt University Berlin

  • White Papers // Sep 2007

    A Feature-Complete Petri Net Semantics for WS-BPEL 2.0 and Its Compiler BPEL2oWFN

    Recently, the emerging standard to describe business processes on top of Web service technology, the Web Service Business Execution Language (WS-BPEL), has been officially specified. The authors present an extension of a Petri net semantics for the Web Service Business Execution Language (WS-BPEL). This extension covers the novel activities and...

    Provided By Humboldt University Berlin

  • White Papers // Jul 2003

    The Duality of Option Investment Strategies for Hedge Funds

    This paper studies the structure of optimal investment strategies for a hedge fund manager, who is typically the general partner and thus a major investor in the fund, using stock index options in the hedge fund's portfolio in a discrete-time framework that overcomes some of the drawbacks of the continuous-time...

    Provided By Humboldt University Berlin