University of Athens

Displaying 1-40 of 45 results

  • White Papers // Dec 2013

    An Improved Compression Technique for Signatures Based on Learning with Errors

    The authors present a new approach to the compression technique of researcher for lattice-based signatures based on Learning With Errors (LWE). Their ideas seem to be particularly suitable for signature schemes whose security, in the random oracle model, is based on standard worst-case computational assumptions. Their signatures are shorter than...

    Provided By University of Athens

  • White Papers // Apr 2013

    Safeguarding a Native XML Database System

    A system with Native XML Database (NXD) can not only store some important data assets such as business to business transaction records and personal medical histories, but also provide e-services to its legitimate users. Since the information stored is so important, those NXD systems are designed with some security goals...

    Provided By University of Athens

  • White Papers // Jul 2012

    On a CCA2-Secure Variant of McEliece in the Standard Model

    The McEliece cryptosystem is the first scheme based on coding theory problems and it makes use of error-correcting codes (binary Goppa codes in the original proposal). It is possible to produce CCA2-secure variants in the random oracle model, but it is of interest to study systems that are secure in...

    Provided By University of Athens

  • White Papers // Jan 2012

    Improved rtPS Scheduling With QoE Metrics in Joint WiMAX/Satellite Networks

    This paper improves a previously proposed scheduling algorithm that is responsible to share the allocated capacity to the up-link traffic of an integrated satellite and WiMAX network. The target of this improvement is to schedule traffic of real time connections based on Quality of Experience (QoE) metrics. After a bibliographic...

    Provided By University of Athens

  • White Papers // Dec 2011

    Efficient Updates for Web-Scale Indexes Over the Cloud

    In this paper, the authors present a distributed system which enables fast and frequent updates on web-scale Inverted Indexes. The proposed update technique allows incremental processing of new or modified data and minimizes the changes required to the index, significantly reducing the update time which is now independent of the...

    Provided By University of Athens

  • White Papers // Oct 2011

    A Front-End, Hadoop-Based Data Management Service for Efficient Federated Clouds

    In the recent years, cloud computing has emerged as the new IT paradigm that promises elastic resources on a pay-per-use basis. The challenges of cloud computing are focused around massive data storage and efficient large scale distributed computation. Hadoop, a community driven Apache project has provided an efficient and cost...

    Provided By University of Athens

  • White Papers // Sep 2011

    VM Placement in Non-Homogeneous IaaS-Clouds

    Infrastructure-as-a-Service (IaaS) cloud providers often combine different hardware components in an attempt to form a single infrastructure. This single infrastructure hides any underlying heterogeneity and complexity of the physical layer. Given a non-homogeneous hardware infrastructure, assigning VMs to Physical Machines (PMs) becomes a particularly challenging task. VM placement decisions have...

    Provided By University of Athens

  • White Papers // Aug 2011

    Peer-to-Peer Media Streaming: Insights and New Developments

    Internet media content delivery started to emerge roughly a decade ago, and it has subsequently had a major impact on network traffic and usage. Although traditional client-server systems were used initially for delivering media content, researchers and practitioners soon realized that Peer-To-Peer (P2P) systems, due to their self-scaling properties, had...

    Provided By University of Athens

  • White Papers // Jul 2011

    Trace-Driven Analysis of Data Forwarding in Opportunistic Networks

    The authors summarize undertaken and ongoing work on the direct and exclusive use of mobile phone traces for assessing the performance of different opportunistic forwarding schemes. Their methods draw on graph-expansion techniques and circumvent the need for more custom simulation software packages. They address a wide range of opportunistic dissemination...

    Provided By University of Athens

  • White Papers // Jun 2011

    Centrality-Driven Scalable Service Migration

    As social networking sites provide increasingly richer context, user-centric service development is expected to explode following the example of User-Generated Content. A major challenge for this emerging paradigm is how to make these exploding in numbers, yet individually of vanishing demand, services available in a cost-effective manner; central to this...

    Provided By University of Athens

  • White Papers // Jun 2011

    Simulations for WDM Mesh Networks With Visual Basic

    Fully optical fiber networks that transmit large quantities of information due to multiple applications or because they serve large urban areas (big and small local telephone exchanges), need to be maintained fault-free at all times of their operation. The protection and restoration strategies are critical. In this paper, the modeling...

    Provided By University of Athens

  • White Papers // Jun 2011

    Rank-Aware Crawling of Hidden Web Sites

    An ever-increasing amount of valuable information on the Web today is stored inside online databases and is accessible only after the users issue a query through a search interface. Such information is collectively called the "HiddenWeb" and is mostly inaccessible by traditional search engine crawlers that scout the Web following...

    Provided By University of Athens

  • White Papers // Apr 2011

    How Much Off-Center are Centrality Metrics for Routing in Opportunistic Networks

    Many network applications rely on stochastic QoS guarantees. With respect to loss-related performance, the Effective Bandwidth/Capacity theory has proved useful for calculating loss probabilities in queues with complex input and server-processes and for formulating simple admission control tests to ensure associated QoS guarantees. This success has motivated the application of...

    Provided By University of Athens

  • White Papers // Mar 2011

    Feedback-Based Learning for Self-Managed Network Elements

    Autonomic network management systems will operate in a volatile network environment; thus they should be able to continuously adapt their decision making mechanism through learning from the behavior of the communication system. In this paper, a novel learning scheme is proposed based on the network-wide collected performance experience, targeting the...

    Provided By University of Athens

  • White Papers // Jan 2011

    Scalable Distributed Service Migration Via Complex Networks Analysis

    With social networking sites providing increasingly richer context, user-centric service creation is expected to follow a similar growth with User-Generated Content. The what-is-often-called User Generated Services paradigm calls for efficient yet scalable solutions for optimally placing service facilities. Typically seen as an instance of the facility location problem, service placement...

    Provided By University of Athens

  • White Papers // Jan 2011

    Performance Analysis of TDMA MAC Schemes for Ad-Hoc Networks With Topology Control

    Traditional omni-directional antennas result in increased mutliuser interference and are known to limit the performance of Medium Access Control (MAC) protocols for ad-hoc networks. Topology control is the capability of a node to control the set of neighbor nodes and in this paper, the impact of using smart antennas and/or...

    Provided By University of Athens

  • White Papers // Dec 2010

    Selling Culture: Implementation of e-Commerce and WAP-Based Prototypes

    Museum stores represent integral parts of the museums that have also a lot to benefit from a successful presence on the web arena. In addition to traditional web sites, carefully designed electronic commerce (e-commerce) sites may increase the potential of museum stores offering possibilities for on-line shopping and other commercial...

    Provided By University of Athens

  • White Papers // Dec 2010

    Value of Information Exposed: Wireless Networking Solutions to the Parking Search Problem

    The authors' work draws on a concrete parking space search application to explore fundamental tradeoffs of wireless networking solutions to the provision of real-life services. In particular, they consider a city area, wherein each vehicle (mobile user) moves towards a chosen destination and seeks vacant parking space in its vicinity....

    Provided By University of Athens

  • White Papers // Nov 2010

    Flexible Use of Cloud Resources Through Profit Maximization and Price Discrimination

    Modern frameworks, such as Hadoop, combined with abundance of computing resources from the cloud, offer a significant opportunity to address long standing challenges in distributed processing. Infrastructure-as-a-Service clouds reduce the investment cost of renting a large data center while distributed processing frameworks are capable of efficiently harvesting the rented physical...

    Provided By University of Athens

  • White Papers // Sep 2010

    Coverage and Capacity Optimization of Self-Managed Future Internet Wireless Networks

    Future Internet network management systems are expected to incorporate self-x capabilities in order to tackle the increased management needs that cannot be addressed through human intervention. Towards this end, Self-NET developed a self-management framework based on the introduction of cognitive capabilities in network elements. In this paper, the experimentation platform...

    Provided By University of Athens

  • White Papers // Jul 2010

    MAD: A Dynamically Adjustable Hybrid Location-And Motion-Based Routing Protocol for VANETs

    This paper proposes a routing protocol that jointly exploits location and motion information in a dynamically adjusted way, towards self-adaptability in different combinations of mobility and node density conditions. The protocol employs a metric of the rate at which a packet approaches its destination over a multi-hop path, as an...

    Provided By University of Athens

  • White Papers // Jun 2010

    Serial Free-Space Optical Relaying Communications Over Gamma-Gamma Atmospheric Turbulence Channels

    In this paper, a study on the end-to-end performance of multi-hop free-space optical wireless systems over turbulence induced fading channels, modeled by the gamma-gamma distribution, is presented. The analysis is carried out for systems employing amplify-and-forward Channel-State-Information-assisted or fixed-gain relays. In order to assess the statistical properties of the end-to-end...

    Provided By University of Athens

  • White Papers // Jun 2010

    A Proof of Concept Environment for Cognitive and Self-X Functionalities

    The recent explosion in the range and capabilities of wireless communications devices is perhaps unequalled in history. Therefore there is a need for introduction of new approaches that tackle the raising complexity. To this end, the authors present the proof of concept environment for cognitive and self-x functionalities as identified...

    Provided By University of Athens

  • White Papers // May 2010

    Visual Modelling of Complex Business Processes with Trees, Overlays and Distortion-Based Displays

    Current approaches to modelling complex business processes fail to scale to large organizations. Key issues are cobweb and labyrinth problems exhibited by conventional box and line metaphors and large numbers of hidden dependencies introduced by compartment-based modularity. The authors have been developing a new approach, Enterprise Modelling Language, based on...

    Provided By University of Athens

  • White Papers // May 2010

    Nefeli: Hint-Based Execution of Workloads in Clouds

    Virtualization of computer systems has made feasible the provision of entire distributed infrastructures in the form of services. Such services do not expose the internal operational and physical characteristics of the underlying machinery to either users or applications. In this way, infrastructures including computers in data-centers, clusters of workstations, and...

    Provided By University of Athens

  • White Papers // Apr 2010

    Efficient and Adaptive Distributed Skyline Computation

    Skyline queries have attracted considerable attention over the last few years, mainly due to their ability to return interesting objects without the need for user-defined scoring functions. In this paper, the authors study the problem of distributed skyline computation and propose an adaptive algorithm towards controlling the degree of parallelism...

    Provided By University of Athens

  • White Papers // Apr 2010

    Minimizing Node Churn in Peer-to-Peer Streaming

    Several Peer-To-Peer (P2P) streaming systems have proved by now their ability to deliver live video streams to hundreds of users. However the inherent instability of the distribution environment poses several obstacles for these systems to manage to deliver a high quality experience to the end users. In this paper, the...

    Provided By University of Athens

  • White Papers // Feb 2010

    Sink Mobility Schemes for Data Extraction in Large Scale WSNs Under Single or Zero Hop Data Forwarding

    A mobile sink is widely considered to facilitate the data collection from energy constrained sensor fields, by having the sink come close to the sensors and conserving precious sensor node energy. The effectiveness of such a data collection approach can be measured in terms of the sensor energy conserved and...

    Provided By University of Athens

  • White Papers // Dec 2009

    Efficient Social-Aware Content Placement in Opportunistic Networks

    As content provisioning becomes the driving application of today's (opportunistic) networking environments and the user generated content explodes, the problem of devising scalable approaches to placing it optimally within a networking structure becomes more important and challenging. Since the well-known k-median optimization problem that is typically formulated to address it...

    Provided By University of Athens

  • White Papers // Jul 2009

    Gossip-Based Search in Multipeer Communication Networks

    The authors study a gossip-based algorithm for searching data objects in a multipeer communication network. All of the nodes in the network are able to communicate with each other. There exists an initiator node that starts a round of searches by randomly querying one or more of its neighbours for...

    Provided By University of Athens

  • White Papers // Jul 2009

    Mobility Management and QoS Support in Wireless Environments: Trends and Open issues

    For quite some time researchers were trying to find viable means to support the quality of services for fixed IP users. This was a difficult task and even up until today there is no universally accepted mechanism to assure the quality of an active service from the one end to...

    Provided By University of Athens

  • White Papers // Jun 2009

    Measuring the Cost of Online Load-Balancing in Distributed Range-Queriable Systems

    Data skew is a well-documented concern for a variety of applications. For instance, it has been widely observed that most Internet-scale applications, including P2P ones, exhibit highly skewed workloads. Failing or departing nodes further reduce the availability of various content. Consequently, resources become scarce, servers get overloaded and throughput can...

    Provided By University of Athens

  • White Papers // Jun 2009

    System-Level Virtualization and Mobile IP to Support Service Mobility

    In many areas of ICT the use of virtualization techniques has decoupled the binding between physical resources and functional roles assigned to them. While the use of virtualization in computing systems is already extremely popular, similar forms of virtualization have been proposed for the network infrastructure as well. In such...

    Provided By University of Athens

  • White Papers // Jun 2009

    The E3 Architecture for Future Cognitive Mobile Networks

    Next generation mobile and wireless systems will enhance the operators' network management capabilities and will considerably improve the users' experience. However, these systems form a complex heterogeneous environment that calls for new management techniques targeting efficiency, robustness and adaptability. Cognition techniques as well as the ability for network components to...

    Provided By University of Athens

  • White Papers // Jun 2009

    Demand and Price Evolution Forecasting as Tools for Facilitating the RoadMapping Process of the Photonic Component Industry

    The photonic component industry is a highly innovative industry with a large value chain. In order to ensure the growth of the industry much effort must be devoted to road mapping activities. In such activities demand and price evolution forecasting tools can prove quite useful in order to help in...

    Provided By University of Athens

  • White Papers // Apr 2009

    Enterprise Model Management Systems

    Decision making in the managerial context is often unstructured, ad-hoc, and complex. It involves structuring and solving the problem, and interpreting the results. A computer-based environment that supports these decision making processes is characterized by a modeling approach that enables the representation of the complexity of the problem, access to...

    Provided By University of Athens

  • White Papers // Mar 2009

    Autonomous Functionalities for Cognitive Radio

    This paper provides an overview on the research activities in autonomous functionalities for cognitive radio and networks, carried out in FP7/E3-project. The identified main research areas within this topic include opportunistic spectrum access and autonomous self-x functionalities for communication nodes. Opportunistic spectrum access delineates innovative topics concerning distributed cooperative spectrum...

    Provided By University of Athens

  • White Papers // Mar 2009

    Dataflow Processing and Optimization on Grid and Cloud Infrastructures

    Complex on-demand data retrieval and processing is a characteristic of several applications and combines the notions of querying & search, information filtering & retrieval, data transformation & analysis, and other data manipulations. Such rich tasks are typically represented by data processing graphs, having arbitrary data operators as nodes and their...

    Provided By University of Athens

  • White Papers // Jan 2009

    Theoretical Model, Simulation Results and Performances of a Secure Chaos-Based Multi-User Communication System

    Single user chaotic communication system is well known and documented in recent years as a system that enhance the security in signal transmission. In this paper, the authors propose a multiuser chaos-based communication system. They will present the results of the investigation of this proposed system, called Chaotic Phase Shift...

    Provided By University of Athens

  • White Papers // Dec 2008

    Study of Randomly Replicated Random Walks for Information Dissemination Over Various Network Topologies

    Information dissemination is important to the robustness or functionality of modern, highly dynamic and of large scale networking environments. Depending on its nature the disseminated information may be destined to the entire network or a subset of its nodes. In this paper, and without loss of generality, it will be...

    Provided By University of Athens

  • White Papers // Jul 2012

    On a CCA2-Secure Variant of McEliece in the Standard Model

    The McEliece cryptosystem is the first scheme based on coding theory problems and it makes use of error-correcting codes (binary Goppa codes in the original proposal). It is possible to produce CCA2-secure variants in the random oracle model, but it is of interest to study systems that are secure in...

    Provided By University of Athens

  • White Papers // May 2010

    Visual Modelling of Complex Business Processes with Trees, Overlays and Distortion-Based Displays

    Current approaches to modelling complex business processes fail to scale to large organizations. Key issues are cobweb and labyrinth problems exhibited by conventional box and line metaphors and large numbers of hidden dependencies introduced by compartment-based modularity. The authors have been developing a new approach, Enterprise Modelling Language, based on...

    Provided By University of Athens

  • White Papers // Apr 2009

    Enterprise Model Management Systems

    Decision making in the managerial context is often unstructured, ad-hoc, and complex. It involves structuring and solving the problem, and interpreting the results. A computer-based environment that supports these decision making processes is characterized by a modeling approach that enables the representation of the complexity of the problem, access to...

    Provided By University of Athens

  • White Papers // Apr 2013

    Safeguarding a Native XML Database System

    A system with Native XML Database (NXD) can not only store some important data assets such as business to business transaction records and personal medical histories, but also provide e-services to its legitimate users. Since the information stored is so important, those NXD systems are designed with some security goals...

    Provided By University of Athens

  • White Papers // Dec 2013

    An Improved Compression Technique for Signatures Based on Learning with Errors

    The authors present a new approach to the compression technique of researcher for lattice-based signatures based on Learning With Errors (LWE). Their ideas seem to be particularly suitable for signature schemes whose security, in the random oracle model, is based on standard worst-case computational assumptions. Their signatures are shorter than...

    Provided By University of Athens

  • White Papers // Jan 2009

    Theoretical Model, Simulation Results and Performances of a Secure Chaos-Based Multi-User Communication System

    Single user chaotic communication system is well known and documented in recent years as a system that enhance the security in signal transmission. In this paper, the authors propose a multiuser chaos-based communication system. They will present the results of the investigation of this proposed system, called Chaotic Phase Shift...

    Provided By University of Athens

  • White Papers // Apr 2003

    Mobile E-Commerce and Location-Based Services: Technology and Requirements

    Advances in Internet and network technology and the rapidly growing number of mobile personal devices result in the fast growth of Mobile E-Commerce, M-Commerce. This paper views M-Commerce as activity of conducting E-commerce transactions using mobile terminals over a wireless network. A special case of M-commerce are Location Based Services...

    Provided By University of Athens

  • White Papers // Jun 2010

    Serial Free-Space Optical Relaying Communications Over Gamma-Gamma Atmospheric Turbulence Channels

    In this paper, a study on the end-to-end performance of multi-hop free-space optical wireless systems over turbulence induced fading channels, modeled by the gamma-gamma distribution, is presented. The analysis is carried out for systems employing amplify-and-forward Channel-State-Information-assisted or fixed-gain relays. In order to assess the statistical properties of the end-to-end...

    Provided By University of Athens

  • White Papers // Jan 2008

    A New Era for the Music Industry: How New Technologies And The Internet Affect The Way Music Is Valued And Have An Impact On Output Quality

    Since its early days, the Internet has been used by the music industry as a powerful marketing tool to promote artists and their products. The purpose of this paper is to present the impact of new technologies and the Internet on the three main actors of the music industry: consumers,...

    Provided By University of Athens

  • White Papers // Dec 2010

    Selling Culture: Implementation of e-Commerce and WAP-Based Prototypes

    Museum stores represent integral parts of the museums that have also a lot to benefit from a successful presence on the web arena. In addition to traditional web sites, carefully designed electronic commerce (e-commerce) sites may increase the potential of museum stores offering possibilities for on-line shopping and other commercial...

    Provided By University of Athens

  • White Papers // Jul 2009

    Gossip-Based Search in Multipeer Communication Networks

    The authors study a gossip-based algorithm for searching data objects in a multipeer communication network. All of the nodes in the network are able to communicate with each other. There exists an initiator node that starts a round of searches by randomly querying one or more of its neighbours for...

    Provided By University of Athens

  • White Papers // Jun 2009

    Demand and Price Evolution Forecasting as Tools for Facilitating the RoadMapping Process of the Photonic Component Industry

    The photonic component industry is a highly innovative industry with a large value chain. In order to ensure the growth of the industry much effort must be devoted to road mapping activities. In such activities demand and price evolution forecasting tools can prove quite useful in order to help in...

    Provided By University of Athens

  • White Papers // Jun 2011

    Rank-Aware Crawling of Hidden Web Sites

    An ever-increasing amount of valuable information on the Web today is stored inside online databases and is accessible only after the users issue a query through a search interface. Such information is collectively called the "HiddenWeb" and is mostly inaccessible by traditional search engine crawlers that scout the Web following...

    Provided By University of Athens

  • White Papers // Jul 2009

    Mobility Management and QoS Support in Wireless Environments: Trends and Open issues

    For quite some time researchers were trying to find viable means to support the quality of services for fixed IP users. This was a difficult task and even up until today there is no universally accepted mechanism to assure the quality of an active service from the one end to...

    Provided By University of Athens

  • White Papers // Jun 2008

    Performance Evaluation of OFDMA Techniques in Multicellular Networks

    Orthogonal Frequency Division Multiple Access (OFDMA) techniques are investigated in this paper. Five sub channel allocation algorithms are analysed and their performance in a multicellular environment is evaluated with simulations. Four schemes of lower complexity, suitable for the early deployment of wireless systems, are compared with a more computationally demanding...

    Provided By University of Athens

  • White Papers // Jan 2011

    Performance Analysis of TDMA MAC Schemes for Ad-Hoc Networks With Topology Control

    Traditional omni-directional antennas result in increased mutliuser interference and are known to limit the performance of Medium Access Control (MAC) protocols for ad-hoc networks. Topology control is the capability of a node to control the set of neighbor nodes and in this paper, the impact of using smart antennas and/or...

    Provided By University of Athens

  • White Papers // Dec 2009

    Efficient Social-Aware Content Placement in Opportunistic Networks

    As content provisioning becomes the driving application of today's (opportunistic) networking environments and the user generated content explodes, the problem of devising scalable approaches to placing it optimally within a networking structure becomes more important and challenging. Since the well-known k-median optimization problem that is typically formulated to address it...

    Provided By University of Athens

  • White Papers // Dec 2008

    Study of Randomly Replicated Random Walks for Information Dissemination Over Various Network Topologies

    Information dissemination is important to the robustness or functionality of modern, highly dynamic and of large scale networking environments. Depending on its nature the disseminated information may be destined to the entire network or a subset of its nodes. In this paper, and without loss of generality, it will be...

    Provided By University of Athens

  • White Papers // Nov 2010

    Flexible Use of Cloud Resources Through Profit Maximization and Price Discrimination

    Modern frameworks, such as Hadoop, combined with abundance of computing resources from the cloud, offer a significant opportunity to address long standing challenges in distributed processing. Infrastructure-as-a-Service clouds reduce the investment cost of renting a large data center while distributed processing frameworks are capable of efficiently harvesting the rented physical...

    Provided By University of Athens

  • White Papers // May 2010

    Nefeli: Hint-Based Execution of Workloads in Clouds

    Virtualization of computer systems has made feasible the provision of entire distributed infrastructures in the form of services. Such services do not expose the internal operational and physical characteristics of the underlying machinery to either users or applications. In this way, infrastructures including computers in data-centers, clusters of workstations, and...

    Provided By University of Athens

  • White Papers // Sep 2011

    VM Placement in Non-Homogeneous IaaS-Clouds

    Infrastructure-as-a-Service (IaaS) cloud providers often combine different hardware components in an attempt to form a single infrastructure. This single infrastructure hides any underlying heterogeneity and complexity of the physical layer. Given a non-homogeneous hardware infrastructure, assigning VMs to Physical Machines (PMs) becomes a particularly challenging task. VM placement decisions have...

    Provided By University of Athens

  • White Papers // Mar 2009

    Autonomous Functionalities for Cognitive Radio

    This paper provides an overview on the research activities in autonomous functionalities for cognitive radio and networks, carried out in FP7/E3-project. The identified main research areas within this topic include opportunistic spectrum access and autonomous self-x functionalities for communication nodes. Opportunistic spectrum access delineates innovative topics concerning distributed cooperative spectrum...

    Provided By University of Athens

  • White Papers // Jun 2011

    Centrality-Driven Scalable Service Migration

    As social networking sites provide increasingly richer context, user-centric service development is expected to explode following the example of User-Generated Content. A major challenge for this emerging paradigm is how to make these exploding in numbers, yet individually of vanishing demand, services available in a cost-effective manner; central to this...

    Provided By University of Athens

  • White Papers // Jul 2011

    Trace-Driven Analysis of Data Forwarding in Opportunistic Networks

    The authors summarize undertaken and ongoing work on the direct and exclusive use of mobile phone traces for assessing the performance of different opportunistic forwarding schemes. Their methods draw on graph-expansion techniques and circumvent the need for more custom simulation software packages. They address a wide range of opportunistic dissemination...

    Provided By University of Athens

  • White Papers // Apr 2011

    How Much Off-Center are Centrality Metrics for Routing in Opportunistic Networks

    Many network applications rely on stochastic QoS guarantees. With respect to loss-related performance, the Effective Bandwidth/Capacity theory has proved useful for calculating loss probabilities in queues with complex input and server-processes and for formulating simple admission control tests to ensure associated QoS guarantees. This success has motivated the application of...

    Provided By University of Athens

  • White Papers // Aug 2011

    Peer-to-Peer Media Streaming: Insights and New Developments

    Internet media content delivery started to emerge roughly a decade ago, and it has subsequently had a major impact on network traffic and usage. Although traditional client-server systems were used initially for delivering media content, researchers and practitioners soon realized that Peer-To-Peer (P2P) systems, due to their self-scaling properties, had...

    Provided By University of Athens

  • White Papers // Mar 2009

    Dataflow Processing and Optimization on Grid and Cloud Infrastructures

    Complex on-demand data retrieval and processing is a characteristic of several applications and combines the notions of querying & search, information filtering & retrieval, data transformation & analysis, and other data manipulations. Such rich tasks are typically represented by data processing graphs, having arbitrary data operators as nodes and their...

    Provided By University of Athens

  • White Papers // Oct 2011

    A Front-End, Hadoop-Based Data Management Service for Efficient Federated Clouds

    In the recent years, cloud computing has emerged as the new IT paradigm that promises elastic resources on a pay-per-use basis. The challenges of cloud computing are focused around massive data storage and efficient large scale distributed computation. Hadoop, a community driven Apache project has provided an efficient and cost...

    Provided By University of Athens

  • White Papers // Jan 2012

    Improved rtPS Scheduling With QoE Metrics in Joint WiMAX/Satellite Networks

    This paper improves a previously proposed scheduling algorithm that is responsible to share the allocated capacity to the up-link traffic of an integrated satellite and WiMAX network. The target of this improvement is to schedule traffic of real time connections based on Quality of Experience (QoE) metrics. After a bibliographic...

    Provided By University of Athens

  • White Papers // Apr 2010

    Efficient and Adaptive Distributed Skyline Computation

    Skyline queries have attracted considerable attention over the last few years, mainly due to their ability to return interesting objects without the need for user-defined scoring functions. In this paper, the authors study the problem of distributed skyline computation and propose an adaptive algorithm towards controlling the degree of parallelism...

    Provided By University of Athens

  • White Papers // Jun 2010

    A Proof of Concept Environment for Cognitive and Self-X Functionalities

    The recent explosion in the range and capabilities of wireless communications devices is perhaps unequalled in history. Therefore there is a need for introduction of new approaches that tackle the raising complexity. To this end, the authors present the proof of concept environment for cognitive and self-x functionalities as identified...

    Provided By University of Athens

  • White Papers // Jun 2009

    The E3 Architecture for Future Cognitive Mobile Networks

    Next generation mobile and wireless systems will enhance the operators' network management capabilities and will considerably improve the users' experience. However, these systems form a complex heterogeneous environment that calls for new management techniques targeting efficiency, robustness and adaptability. Cognition techniques as well as the ability for network components to...

    Provided By University of Athens

  • White Papers // Mar 2011

    Feedback-Based Learning for Self-Managed Network Elements

    Autonomic network management systems will operate in a volatile network environment; thus they should be able to continuously adapt their decision making mechanism through learning from the behavior of the communication system. In this paper, a novel learning scheme is proposed based on the network-wide collected performance experience, targeting the...

    Provided By University of Athens

  • White Papers // Sep 2010

    Coverage and Capacity Optimization of Self-Managed Future Internet Wireless Networks

    Future Internet network management systems are expected to incorporate self-x capabilities in order to tackle the increased management needs that cannot be addressed through human intervention. Towards this end, Self-NET developed a self-management framework based on the introduction of cognitive capabilities in network elements. In this paper, the experimentation platform...

    Provided By University of Athens

  • White Papers // Dec 2011

    Efficient Updates for Web-Scale Indexes Over the Cloud

    In this paper, the authors present a distributed system which enables fast and frequent updates on web-scale Inverted Indexes. The proposed update technique allows incremental processing of new or modified data and minimizes the changes required to the index, significantly reducing the update time which is now independent of the...

    Provided By University of Athens

  • White Papers // Jun 2009

    Measuring the Cost of Online Load-Balancing in Distributed Range-Queriable Systems

    Data skew is a well-documented concern for a variety of applications. For instance, it has been widely observed that most Internet-scale applications, including P2P ones, exhibit highly skewed workloads. Failing or departing nodes further reduce the availability of various content. Consequently, resources become scarce, servers get overloaded and throughput can...

    Provided By University of Athens

  • White Papers // Sep 2008

    Evaluation Of Credit Risk Based On Firm Performance

    In this paper, the authors investigate whether technical efficiency is an important ex-ante predictor of business failure. They use samples of French textiles, wood, and R&D companies to obtain efficiency estimates for individual firms in each industry. These efficiency measures are derived from a directional technology distance function constructed empirically...

    Provided By University of Athens

  • White Papers // Jun 2011

    Simulations for WDM Mesh Networks With Visual Basic

    Fully optical fiber networks that transmit large quantities of information due to multiple applications or because they serve large urban areas (big and small local telephone exchanges), need to be maintained fault-free at all times of their operation. The protection and restoration strategies are critical. In this paper, the modeling...

    Provided By University of Athens

  • White Papers // Jun 2009

    System-Level Virtualization and Mobile IP to Support Service Mobility

    In many areas of ICT the use of virtualization techniques has decoupled the binding between physical resources and functional roles assigned to them. While the use of virtualization in computing systems is already extremely popular, similar forms of virtualization have been proposed for the network infrastructure as well. In such...

    Provided By University of Athens

  • White Papers // Oct 2008

    A Characterization of Maximum Entropy Spatially Correlated Wireless Channel Models

    The authors consider the use of entropy maximization methods as a tool to generate fading models for Multiple-Input Multiple-Output (MIMO) spatially correlated flat-fading channels. They focus in particular on various assumptions about the degree of knowledge on the full covariance matrix of the channel (namely in the power constraint, rank...

    Provided By University of Athens