University of Coimbra

Displaying 1-40 of 49 results

  • White Papers // May 2013

    Keep It Simple - The Challenge of Interlaced IT Architecture at Gothaer Systems

    The German direct insurer Gothaer Insurance Group is among the largest insurance companies in Germany. In recent years, Gothaer was facing the challenge of replacing its existing collection systems. The replacement system was one of SAP's key modules for Insurance Solution, a standard software product called FS-CD (Financial Services -...

    Provided By University of Coimbra

  • White Papers // May 2013

    Managing Data Quality With ERP Systems - Insights From the Insurance Sector

    Data Quality Management (DQM) gains importance due to the increasing amount and diversity of data as well as data's critical impact on organizational success. Enterprise Resource Planning (ERP) systems, which are used in most manufacturing and service organizations, provide a platform for data integration. The information-intensive insurance sector, with its...

    Provided By University of Coimbra

  • White Papers // May 2013

    Assessing the Assessors - An Overview and Evaluation of It Project Success Reports

    A great number of scholars in the information systems discipline motivate their research referring to poor performance of Information Technology (IT) projects, which is reported in prior success studies. However, the rigour of such success studies has either not been analyzed to an adequate degree or in case of the...

    Provided By University of Coimbra

  • White Papers // May 2013

    Cloud Service Certifications: Measuring Consumers' Preferences for Assurances

    Cloud computing by now has gained wide recognition in business and is becoming increasingly important for consumers. However, consumers experience uncertainties, such as security, privacy, and vendor lock-in. Certifications provide assurances and may mitigate uncertainties, making cloud service certifications a core focus of the European Union's cloud strategy and various...

    Provided By University of Coimbra

  • White Papers // Feb 2012

    A Cooperative Protocol for Jamming Eavesdroppers in Wireless Networks

    The authors present a jamming protocol for secrecy-enhanced wireless networks in which otherwise silent devices are selected as jammers to cause interference to potential eavesdroppers. This cooperative protocol includes several jammer selection policies that lead to different levels of secrecy - energy tradeoffs. Their results show that there is some...

    Provided By University of Coimbra

  • White Papers // Oct 2011

    Cognitive Radio: Technology Survey and Future Research Directions

    Currently, the radio spectrum is statically allocated and divided between licensed and unlicensed frequencies. Due to this inflexible regulatory policy, some frequency bands are growing in scarcity, while large portions of the entire radio spectrum remain unused independently of time and location. Cognitive Radio is a recent network paradigm that...

    Provided By University of Coimbra

  • White Papers // Jul 2011

    Financial Constraints And Exports: An Analysis Of Portuguese Firms During The European Monetary Integration

    Financial constraints are a key determinant that hinders firms' ability to export. This paper analyses the nexus between these constraints and firms' engagement in international trade, as well as it explores the impact of the European monetary integration process upon firms' financial constraints. Therefore, the authors estimate cash to cash-flow...

    Provided By University of Coimbra

  • White Papers // Jul 2011

    A Decision and Reconstruction Support Framework: Elaborating on Web Technology

    In earlier research, the authors focused on the development of information models for distributed GDSS (Group Decision Support Systems), closing the gap between the study of concurrency control mechanisms, document structuring and decision tracking. The properties of the developed information model (implemented into a GDSS software tool) not only achieved...

    Provided By University of Coimbra

  • White Papers // May 2011

    Do Financial Constraints Threat The Innovation Process? Evidence From Portuguese Firms

    This paper investigates the extent to which R&D investment and innovation are financially constrained. For that purpose, the authors resort to the estimation of a selection model of R&D investment, a simultaneous equations probit model of innovation and constraints and cash to cash-flow sensitivities upon an unique and newly assembled...

    Provided By University of Coimbra

  • White Papers // Mar 2011

    Enabling Network-layer Security on IPv6 Wireless Sensor Networks

    Security plays a vital role in enabling future integration of Wireless Sensor Networks (WSNs) with the Internet. Although security in WSNs is a mature field of research and many proposals currently exist that can address particular security threats, how to guarantee end-to-end security at the network-layer for IPv6-enabled WSNs remains...

    Provided By University of Coimbra

  • White Papers // Mar 2011

    Channel Quality of IEEE 802.15.4 Based Sensor Networks

    Channel quality of wireless networks is a topic considered by most of the network practitioners and researchers. There are several factors that affect the quality of a wireless channel, and therefore, the reliability of data delivery. Therefore, an understanding of the characteristics of a wireless channel is an essential part...

    Provided By University of Coimbra

  • White Papers // Mar 2011

    A Framework for Integrating WSNs and External Environments

    The Wireless Sensor Network (WSN) offers a diversity of applications in most of the fields, including healthcare, environmental monitoring, military, and smart homes. However, most of the important applications of WSNs cannot operate in complete isolation and therefore it is necessary to have a method for interconnecting WSNs with external...

    Provided By University of Coimbra

  • White Papers // Jan 2011

    Accession To The European Union, Interest Rates And Indebtedness: Greece And Portugal

    The increase in both public and private indebtedness has been one of the main macroeconomic developments in recent years. This trend has been accompanied by large current account deficits, especially in smaller countries, such as Greece and Portugal. One possible explanation for this behaviour is the reduction in interest rates...

    Provided By University of Coimbra

  • White Papers // Oct 2010

    Fostering International Entrepreneurship: Are SMEs Targeted Adequately by Official Foreign Trade Promotion Schemes?

    Small businesses face size-specific barriers with regard to the development of foreign markets. To counteract these structural disadvantages, governments worldwide have created a large number of different institutions and instruments to support the internationalisation of small firms. Grounded in the theoretical framework of the resource-based view, the authors' study analyses...

    Provided By University of Coimbra

  • White Papers // Oct 2010

    Towards Mobility Support in Wireless Sensor Networks

    Wireless sensor networks have been the subject of intensive research over the last few years. Nevertheless, although the concept is now well defined, network operability, integrity and reliability are not yet at desirable levels. This paper focuses on the most basic requirements for the massive application of wireless sensor networks...

    Provided By University of Coimbra

  • White Papers // Sep 2010

    The Duration Of Business Cycle Expansions And Contractions: Are There Change-Points In Duration Dependence?

    The issue of whether the likelihood of an expansion or contraction ending is dependent on its age, i.e whether they are duration dependent is widely addressed in the business cycles literature and evidence of positive duration dependence is found in several studies. However, there is an important issue that has...

    Provided By University of Coimbra

  • White Papers // Jul 2010

    A Secure Interconnection Model for IPv6 Enabled Wireless Sensor Networks

    The usage of IPv6 on Wireless Sensor Networks (WSNs) can enable the integration of existing and new sensing applications with the Internet, therefore contributing to a major evolution towards the realization of the internet of things. The authors believe this vision to be realizable only if security is properly addressed....

    Provided By University of Coimbra

  • White Papers // Jul 2010

    Measuring Firms- Financial Constraints: Evidence For Portugal Through Different Approaches

    Today's shortage of financial resources calls for the attention of researchers to the problem of financial constraints faced by firms. In this paper, the authors analyze firms' financial constraints by estimating both investment-cash flow sensitivities and cash-cash flow sensitivities upon a large unbalanced panel of Portuguese firms in order to...

    Provided By University of Coimbra

  • White Papers // Jul 2010

    Financial Constraints: Are There Differences Between Manufacturing And Services?

    This paper is the first to explicitly explore the differences in firms' financial constraints between and within sectors of economic activity, by estimating the sensitivities of cash holdings to cash-flow upon an unique dataset of Portuguese firms. It shows that, not only there are remarkable differences between sectors and, especially,...

    Provided By University of Coimbra

  • White Papers // Feb 2010

    A Proxy-Based Mobility Solution for Critical WSN Applications

    The potential of Wireless Sensor Networks (WSNs) for a wide range of scenarios has led to some experiments which explore their use in critical applications, such as soldier health monitoring, fire rescue or healthcare. Nevertheless, many obstacles to the effective use of WSNs in these scenarios exist, mainly due to...

    Provided By University of Coimbra

  • White Papers // Jan 2010

    Consolidation Of Accounts Of Public Groups: The Case Of Portuguese Public Universities

    The consolidation of financial information is an important aspect to be taken into consideration by financial directors and politicians in the decision making process. Furthermore than a precious management tool for politicians and technicians, the consolidation of financial information also contributes towards strengthening the transparency of information, for citizens as...

    Provided By University of Coimbra

  • White Papers // Jan 2010

    Is Foreign Trade Important For Regional Growth? Empirical Evidence From Portugal

    The aim of this paper is to investigate whether openness, exports shares or trade balances affect regional growth in Portugal. Human capital is also considered as a conditional factor to growth, expressed by the rate of success in high school education. Thus, the authors analyse whether the combination of international...

    Provided By University of Coimbra

  • White Papers // Jan 2010

    The Demand For Excess Reserves In The Euro Area And The Impact Of The Current Credit Crisis

    One of the risks that banks need to manage, in their financial intermediation activities, is liquidity risk. Thus, banks hold reserves for precautionary reasons, in order to keep enough cash to meet their obligations. In this paper, the authors analyze the demand for excess reserves by Euro Area banks, since...

    Provided By University of Coimbra

  • White Papers // Nov 2009

    Survey on Data Routing in Wireless Sensor Networks

    Routing in sensor networks is very challenging, due to several characteristics that distinguish them from contemporary communication and wireless ad-hoc networks. Many new goal and data-oriented algorithms have been proposed for the problem of routing data in sensor networks. Most routing protocols can be classified as data-centric, hierarchical, location-based or...

    Provided By University of Coimbra

  • White Papers // Nov 2009

    Use of GPS and 6LowPAN in Mobile Multi-Sink Wireless Sensor Networks - Issues and Feasibility

    Wireless Sensor Networks (WSNs) have been the subject of intensive research in the past few years. Several factors have contributed to this, among which the enormous potential for application of WSNs in almost every aspect of day-to-day life is the predominant one. In spite of this, real deployments of WSNs...

    Provided By University of Coimbra

  • White Papers // Sep 2009

    Simulation Platform for Wireless Sensor Networks Based on the TrueTime Toolbox

    Research on Wireless Sensor Networks (WSNs) has received considerable attention in the last few years due to their unique characteristics, including, flexibility, self-organization, easy deployment, which make them an ideal candidate for lowcost monitoring. In order to help WSN planning and to enable the design of new protocols and applications...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    QoS Mapping and Adaptation in Next Generation Networks

    The end-to-end Quality of Service (QoS) control is one of the key factors to the success of next generation networks. Therefore, this paper presents a session-aware QoS mapping and adaptation mechanism that maps the session QoS requirements into the most suitable network service class across heterogeneous mobile networks as well...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    On Autonomic QoS Provisioning for Voice Over IP Services

    In this paper, the authors present a framework for autonomic QoS provisioning for VoIP services. The central role is held by a Measurement Based Admission Control algorithm which incorporates three innovations. First, the mathematical under-pining obeys a non-parametric approach, removing the dependency on a priori assumed characteristics of the underlying...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Internet Quality of Service: A Bigger Picture

    Quality of Service is one of the major research topics in computer communications, not at last reflected by the immense number of work published by today. In fact, continuous innovation is shaping this versatile subject in many aspects and it's nearly impossible to keep track for an individual. For this...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Multi-Perspective Optimization of G?ANT Inter-Domain Traffic

    Inter-domain traffic engineering is a key issue when resource optimization across autonomous systems boundaries is concerned. Mapping inter-domain traffic flows into existing service level agreements is, in general, a complex problem, for which an optimization tool is needed. This paper aims at demonstrating the advantages of using such a tool...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Non-Parametric and Self-Tuning Measurement-Based Admission Control

    The Measurement-based Admission Control algorithm presented in this paper has been devised to overcome three, widely known shortcomings inherent to common design. Firstly, its configuration parameter strictly corresponds to standard QoS definitions in Service Level Agreements, namely packet loss probability. While the latter is featured by a set of alternative...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    A Multi-Scale Tomographic Algorithm for Detecting and Classifying Traffic Anomalies

    The occurrence of a traffic anomaly is always responsible for a degradation of performance. The anomaly can be observable, at some scale, in different ways: an increase in the number of packets, an increase in the number of bytes, a concentration of packets around a port number, etc. In this...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    A Resource Reservation Protocol Supporting QoS-Aware Multicast Trees for Next Generation Networks

    It is expected that next generation of networks will handle new types of services which are destined to large audiences and have different QoS requirements. From the transport point of view, multicast is the most suitable technology for the required group communication services, since it avoids packets duplication and saves...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Q3M: QoS Architecture for Multi-User Mobile Multimedia Sessions in 4G Systems

    Fourth Generation systems (4G) will provide multimedia group communication sessions to multiple mobile users with distinct requirements. This way, it is expected the control of the quality level, connectivity and ubiquitous access for multi-user multimedia sessions across heterogeneous and mobile networks with seamless capability. This paper analyses the requirements of...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    WiRA: An Approach for Resource Control in WiMAX Systems

    The emerging of Quality of Service (QoS)-enabled broadband wireless access technologies brings inter-networking facilities by allowing high speed communications with traffic differentiation and bandwidth guarantees. However, end-to-end QoS in heterogeneous environments, where the network may be composed of links with different bandwidth capacities and QoS models, is still an open...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    A Framework for the Establishment of Inter-Domain, On-Demand VPNs

    Virtual Private Networks (VPNs) are a popular and cost-effective means to build wide-area corporate networks, since they provide bandwidth, privacy and security for a fraction of the cost of private networks. However, establishing VPNs across different domains (inter-domain VPNs) is still a cumbersome task, requiring human-based negotiation between involved carriers,...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Scalable Multimedia Group Communications Through the Over-Provisioning of Network Resources

    The efficient management of network resources together with the Quality of Service (QoS) control of real-time multimedia group communication sessions in Next Generation Networks (NGN) is still a challenging research goal. The unified control of the session quality level, distribution tree allocation and network resources in NGN will increase the...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Stabilizing Intelligent Route Control: Randomized Path Monitoring, Randomized Path Switching or History-Aware Path Switching?

    Multi-homing Intelligent Route Control (IRC) plays a significant role in improving the performance of Internet access of IP network customers through dynamic path switching. However, in a competitive environment, IRC systems may introduce persistent route oscillations, causing significant performance degradation. In this paper, the authors explore three design alternatives to...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Scalable Resource Provisioning for Multi-User Communications in Next Generation Networks

    The great demand for real-time multimedia sessions encompassing groups of users (multi-user), associated with the limitations of the current Internet in providing quality assurance, has raised challenges for defining the best mechanisms to deploy the Next Generation of Networks (NGN). There is a consensus that an efficient and scalable provisioning...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Quality Level Control for Multi-User Sessions in Future Generation Networks

    Real-time multimedia sessions are now present in the people daily live experience, and will be among the most important applications in future generation networks. The distribution of those sessions, towards fixed and mobile users, with Quality of Experience (QoE) assurance is important to attract and keep customers, while increasing the...

    Provided By University of Coimbra

  • White Papers // Jul 2010

    Measuring Firms- Financial Constraints: Evidence For Portugal Through Different Approaches

    Today's shortage of financial resources calls for the attention of researchers to the problem of financial constraints faced by firms. In this paper, the authors analyze firms' financial constraints by estimating both investment-cash flow sensitivities and cash-cash flow sensitivities upon a large unbalanced panel of Portuguese firms in order to...

    Provided By University of Coimbra

  • White Papers // Nov 2009

    Use of GPS and 6LowPAN in Mobile Multi-Sink Wireless Sensor Networks - Issues and Feasibility

    Wireless Sensor Networks (WSNs) have been the subject of intensive research in the past few years. Several factors have contributed to this, among which the enormous potential for application of WSNs in almost every aspect of day-to-day life is the predominant one. In spite of this, real deployments of WSNs...

    Provided By University of Coimbra

  • White Papers // Sep 2009

    Simulation Platform for Wireless Sensor Networks Based on the TrueTime Toolbox

    Research on Wireless Sensor Networks (WSNs) has received considerable attention in the last few years due to their unique characteristics, including, flexibility, self-organization, easy deployment, which make them an ideal candidate for lowcost monitoring. In order to help WSN planning and to enable the design of new protocols and applications...

    Provided By University of Coimbra

  • White Papers // Nov 2009

    Survey on Data Routing in Wireless Sensor Networks

    Routing in sensor networks is very challenging, due to several characteristics that distinguish them from contemporary communication and wireless ad-hoc networks. Many new goal and data-oriented algorithms have been proposed for the problem of routing data in sensor networks. Most routing protocols can be classified as data-centric, hierarchical, location-based or...

    Provided By University of Coimbra

  • White Papers // Feb 2010

    A Proxy-Based Mobility Solution for Critical WSN Applications

    The potential of Wireless Sensor Networks (WSNs) for a wide range of scenarios has led to some experiments which explore their use in critical applications, such as soldier health monitoring, fire rescue or healthcare. Nevertheless, many obstacles to the effective use of WSNs in these scenarios exist, mainly due to...

    Provided By University of Coimbra

  • White Papers // Mar 2011

    Enabling Network-layer Security on IPv6 Wireless Sensor Networks

    Security plays a vital role in enabling future integration of Wireless Sensor Networks (WSNs) with the Internet. Although security in WSNs is a mature field of research and many proposals currently exist that can address particular security threats, how to guarantee end-to-end security at the network-layer for IPv6-enabled WSNs remains...

    Provided By University of Coimbra

  • White Papers // Mar 2011

    Channel Quality of IEEE 802.15.4 Based Sensor Networks

    Channel quality of wireless networks is a topic considered by most of the network practitioners and researchers. There are several factors that affect the quality of a wireless channel, and therefore, the reliability of data delivery. Therefore, an understanding of the characteristics of a wireless channel is an essential part...

    Provided By University of Coimbra

  • White Papers // Oct 2010

    Towards Mobility Support in Wireless Sensor Networks

    Wireless sensor networks have been the subject of intensive research over the last few years. Nevertheless, although the concept is now well defined, network operability, integrity and reliability are not yet at desirable levels. This paper focuses on the most basic requirements for the massive application of wireless sensor networks...

    Provided By University of Coimbra

  • White Papers // Jul 2010

    A Secure Interconnection Model for IPv6 Enabled Wireless Sensor Networks

    The usage of IPv6 on Wireless Sensor Networks (WSNs) can enable the integration of existing and new sensing applications with the Internet, therefore contributing to a major evolution towards the realization of the internet of things. The authors believe this vision to be realizable only if security is properly addressed....

    Provided By University of Coimbra

  • White Papers // Mar 2011

    A Framework for Integrating WSNs and External Environments

    The Wireless Sensor Network (WSN) offers a diversity of applications in most of the fields, including healthcare, environmental monitoring, military, and smart homes. However, most of the important applications of WSNs cannot operate in complete isolation and therefore it is necessary to have a method for interconnecting WSNs with external...

    Provided By University of Coimbra

  • White Papers // Jul 2011

    Financial Constraints And Exports: An Analysis Of Portuguese Firms During The European Monetary Integration

    Financial constraints are a key determinant that hinders firms' ability to export. This paper analyses the nexus between these constraints and firms' engagement in international trade, as well as it explores the impact of the European monetary integration process upon firms' financial constraints. Therefore, the authors estimate cash to cash-flow...

    Provided By University of Coimbra

  • White Papers // Jul 2010

    Financial Constraints: Are There Differences Between Manufacturing And Services?

    This paper is the first to explicitly explore the differences in firms' financial constraints between and within sectors of economic activity, by estimating the sensitivities of cash holdings to cash-flow upon an unique dataset of Portuguese firms. It shows that, not only there are remarkable differences between sectors and, especially,...

    Provided By University of Coimbra

  • White Papers // May 2009

    No Deep Pockets: Some Stylized Results On Firms' Financial Constraints

    This paper is a brief survey of recent empirical work on financial constraints faced by firms. It is organized as a series of stylized results which mirror what is generally understood about severity of financial constraints and effects that they have upon firms. This paper shows that the financial constraint...

    Provided By University of Coimbra

  • White Papers // May 2011

    Do Financial Constraints Threat The Innovation Process? Evidence From Portuguese Firms

    This paper investigates the extent to which R&D investment and innovation are financially constrained. For that purpose, the authors resort to the estimation of a selection model of R&D investment, a simultaneous equations probit model of innovation and constraints and cash to cash-flow sensitivities upon an unique and newly assembled...

    Provided By University of Coimbra

  • White Papers // Jan 2010

    The Demand For Excess Reserves In The Euro Area And The Impact Of The Current Credit Crisis

    One of the risks that banks need to manage, in their financial intermediation activities, is liquidity risk. Thus, banks hold reserves for precautionary reasons, in order to keep enough cash to meet their obligations. In this paper, the authors analyze the demand for excess reserves by Euro Area banks, since...

    Provided By University of Coimbra

  • White Papers // Jan 2011

    Accession To The European Union, Interest Rates And Indebtedness: Greece And Portugal

    The increase in both public and private indebtedness has been one of the main macroeconomic developments in recent years. This trend has been accompanied by large current account deficits, especially in smaller countries, such as Greece and Portugal. One possible explanation for this behaviour is the reduction in interest rates...

    Provided By University of Coimbra

  • White Papers // Jul 2011

    A Decision and Reconstruction Support Framework: Elaborating on Web Technology

    In earlier research, the authors focused on the development of information models for distributed GDSS (Group Decision Support Systems), closing the gap between the study of concurrency control mechanisms, document structuring and decision tracking. The properties of the developed information model (implemented into a GDSS software tool) not only achieved...

    Provided By University of Coimbra

  • White Papers // Oct 2011

    Cognitive Radio: Technology Survey and Future Research Directions

    Currently, the radio spectrum is statically allocated and divided between licensed and unlicensed frequencies. Due to this inflexible regulatory policy, some frequency bands are growing in scarcity, while large portions of the entire radio spectrum remain unused independently of time and location. Cognitive Radio is a recent network paradigm that...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Network Simulation and Performance Evaluation of WiMAX Extensions for Isolated Research Data Networks

    IEEE 802.16 is yet a very recent technology and released hardware does frequently only support standards partially. The same applies to public available simulation tools, in particular for NS-2. As the latter is the de-facto standard in science and as the authors use it for their research in the context...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    IP and WiMAX Coalition

    The IEEE 802.16 standard focuses on the MAC and physical layers. Its deployment needs a seamless integration with IP related protocols. This paper presents a review of approaches for IP support over WiMAX, including current efforts being developed to specify end-to-end architectures. The QoS mapping between IP QoS settings and...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    QoS Mapping and Adaptation in Next Generation Networks

    The end-to-end Quality of Service (QoS) control is one of the key factors to the success of next generation networks. Therefore, this paper presents a session-aware QoS mapping and adaptation mechanism that maps the session QoS requirements into the most suitable network service class across heterogeneous mobile networks as well...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    On Autonomic QoS Provisioning for Voice Over IP Services

    In this paper, the authors present a framework for autonomic QoS provisioning for VoIP services. The central role is held by a Measurement Based Admission Control algorithm which incorporates three innovations. First, the mathematical under-pining obeys a non-parametric approach, removing the dependency on a priori assumed characteristics of the underlying...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Internet Quality of Service: A Bigger Picture

    Quality of Service is one of the major research topics in computer communications, not at last reflected by the immense number of work published by today. In fact, continuous innovation is shaping this versatile subject in many aspects and it's nearly impossible to keep track for an individual. For this...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Multi-Perspective Optimization of G?ANT Inter-Domain Traffic

    Inter-domain traffic engineering is a key issue when resource optimization across autonomous systems boundaries is concerned. Mapping inter-domain traffic flows into existing service level agreements is, in general, a complex problem, for which an optimization tool is needed. This paper aims at demonstrating the advantages of using such a tool...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Non-Parametric and Self-Tuning Measurement-Based Admission Control

    The Measurement-based Admission Control algorithm presented in this paper has been devised to overcome three, widely known shortcomings inherent to common design. Firstly, its configuration parameter strictly corresponds to standard QoS definitions in Service Level Agreements, namely packet loss probability. While the latter is featured by a set of alternative...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    A Multi-Scale Tomographic Algorithm for Detecting and Classifying Traffic Anomalies

    The occurrence of a traffic anomaly is always responsible for a degradation of performance. The anomaly can be observable, at some scale, in different ways: an increase in the number of packets, an increase in the number of bytes, a concentration of packets around a port number, etc. In this...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    A Resource Reservation Protocol Supporting QoS-Aware Multicast Trees for Next Generation Networks

    It is expected that next generation of networks will handle new types of services which are destined to large audiences and have different QoS requirements. From the transport point of view, multicast is the most suitable technology for the required group communication services, since it avoids packets duplication and saves...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Q3M: QoS Architecture for Multi-User Mobile Multimedia Sessions in 4G Systems

    Fourth Generation systems (4G) will provide multimedia group communication sessions to multiple mobile users with distinct requirements. This way, it is expected the control of the quality level, connectivity and ubiquitous access for multi-user multimedia sessions across heterogeneous and mobile networks with seamless capability. This paper analyses the requirements of...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    WiRA: An Approach for Resource Control in WiMAX Systems

    The emerging of Quality of Service (QoS)-enabled broadband wireless access technologies brings inter-networking facilities by allowing high speed communications with traffic differentiation and bandwidth guarantees. However, end-to-end QoS in heterogeneous environments, where the network may be composed of links with different bandwidth capacities and QoS models, is still an open...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    A Framework for the Establishment of Inter-Domain, On-Demand VPNs

    Virtual Private Networks (VPNs) are a popular and cost-effective means to build wide-area corporate networks, since they provide bandwidth, privacy and security for a fraction of the cost of private networks. However, establishing VPNs across different domains (inter-domain VPNs) is still a cumbersome task, requiring human-based negotiation between involved carriers,...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Scalable Multimedia Group Communications Through the Over-Provisioning of Network Resources

    The efficient management of network resources together with the Quality of Service (QoS) control of real-time multimedia group communication sessions in Next Generation Networks (NGN) is still a challenging research goal. The unified control of the session quality level, distribution tree allocation and network resources in NGN will increase the...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Stabilizing Intelligent Route Control: Randomized Path Monitoring, Randomized Path Switching or History-Aware Path Switching?

    Multi-homing Intelligent Route Control (IRC) plays a significant role in improving the performance of Internet access of IP network customers through dynamic path switching. However, in a competitive environment, IRC systems may introduce persistent route oscillations, causing significant performance degradation. In this paper, the authors explore three design alternatives to...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Scalable Resource Provisioning for Multi-User Communications in Next Generation Networks

    The great demand for real-time multimedia sessions encompassing groups of users (multi-user), associated with the limitations of the current Internet in providing quality assurance, has raised challenges for defining the best mechanisms to deploy the Next Generation of Networks (NGN). There is a consensus that an efficient and scalable provisioning...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Quality Level Control for Multi-User Sessions in Future Generation Networks

    Real-time multimedia sessions are now present in the people daily live experience, and will be among the most important applications in future generation networks. The distribution of those sessions, towards fixed and mobile users, with Quality of Experience (QoE) assurance is important to attract and keep customers, while increasing the...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    What if the End Systems Knew the Bandwidth Available in the Network?

    In this paper, the authors propose Open Box Transport Protocol (OBP), a mechanism that provides information to the end systems about the current state of the network path. With this information (essentially the available bandwidth and the most restricted link capacity) the end systems can efficiently use the network resources....

    Provided By University of Coimbra

  • White Papers // Aug 2009

    HyPath: An Approach for Hybrid On-Path Offpath End-to-End Signaling

    In a multi-domain Internet that offers Quality of Service guaranties, there is the need of signaling among the domain entities that are responsible for the management of Quality of Service. Because different domains have different network protocols and topologies, there is no solution that is able to signal these entities...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Quality of Service and Quality of Experience in Video Streaming

    Real-time video sessions, such as IPTV and video streaming, will be among the most important applications in future networking systems. The delivery of those sessions based on Quality of Service (QoS) techniques assures packet differentiation and indicate the impact of multimedia traffic on the network performance, but do not reflect...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    Seamless Mobility of Senders Transmitting Multi-User Sessions Over Heterogeneous Networks

    The development of wireless technologies together with the increasing portability of telecommunication devices lead to the necessity to develop communication systems capable of supporting a seamless mobility experience to end-users. Moreover, the arising of multi-user real-time services has emphasized the importance of the multicast communication to deliver content to multiple...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    A Seamless Mobility Scenario for IP Over WiMAX

    WiMAX is a broadband wireless access technology facing the challenges of 3G and beyond communication systems. As frequency licensing is becoming commercially available throughout the world, it is still unclear whether WiMAX will be better positioned than its main competitors, such as UMTS. Therefore, it is critical to evaluate the...

    Provided By University of Coimbra

  • White Papers // Aug 2009

    OBP: Stability and Performance

    In this paper, the authors study the stability of Open Box Transport Protocol (OBP), an explicit congestion control protocol that provides information to the end systems about the current state of the network path. To support the study they deduced the OBP transfer function to study the protocol stability, which...

    Provided By University of Coimbra