Universidade do Porto

Displaying 1-38 of 38 results

  • White Papers // Mar 2012

    Systematic Network Coding With the Aid of a Full-Duplex Relay

    A characterization of systematic network coding over multi-hop wireless networks is key towards understanding the trade-off between complexity and delay performance of networks that preserve the systematic structure. This paper studies the case of a relay channel, where the source's objective is to deliver a given number of data packets...

    Provided By Universidade do Porto

  • White Papers // Jul 2011

    Macroeconomic Effects Of Fiscal Consolidations In A DSGE Model For The Euro Area: Does Composition Matter?

    The authors develop a new-Keynesian DSGE model with an extended fiscal policy block to assess the conditions for expansionary fiscal consolidations. In addition to several taxes, they consider public employment expenditures and government spending, which may have different degrees of productivity. They calibrate the model for the Euro Area and...

    Provided By Universidade do Porto

  • White Papers // Jun 2011

    Lumpy Investment In Sticky Information General Equilibrium

    This paper introduces lumpy micro-level investment into a sticky information general equilibrium model. Lumpy investment arises because of inattentiveness in capital investment decisions instead of the more popular assumption of non-convex adjustment costs. Sticky information is the only source of rigidity in the model and it is pervasive to all...

    Provided By Universidade do Porto

  • White Papers // Mar 2011

    Position-Based Jamming for Enhanced Wireless Secrecy

    Signal interference and packet collisions are typically viewed as negative factors that hinder wireless communication networks. When security is the primary concern, signal interference may actually be very helpful. Starting with a stochastic network model, the authors are able to show that packet collisions caused by jamming nodes can indeed...

    Provided By Universidade do Porto

  • White Papers // Mar 2011

    Jammer Selection Policies for Secure Wireless Networks

    The authors consider a wireless network scenario in which the communicating nodes are assisted by a number of jammers. The goal of the jammers is to obstruct potential eavesdroppers while restricting the harmful interference experienced by the legitimate receiver. Based on a stochastic network model, they are able to show...

    Provided By Universidade do Porto

  • White Papers // Mar 2011

    Friendly Jamming for Wireless Secrecy

    The authors analyze the role of jamming as a means to increase the security of wireless systems. Specifically, they characterize the impact of cooperative/friendly jamming on the secrecy outage probability of a quasi-static wiretap fading channel. They introduce jamming coverage and jamming efficiency as security metrics, and evaluate the performance...

    Provided By Universidade do Porto

  • White Papers // Feb 2011

    Universities And Authors: A Ranking For International Finance

    The authors rank universities and colleges and they list the top 100 authors in the sub-field of International Finance using the EconLit database and measuring quality by the number of American Economic Review-equivalent articles published over the ten-year period 1996-2005. They observe that there is some dissimilarity between the ranking...

    Provided By Universidade do Porto

  • White Papers // Feb 2011

    Financial Constraints And Exports: Evidence From Portuguese Manufacturing Firms

    This paper analyzes the links between financial constraints and firm export behavior, at the firm level, by using data on Portuguese manufacturing enterprises. Theoretical models of Chaney (2005) and Manova (2010) suggest that credit constraints are detrimental for exports but no model explains consistently why exports could improve firms? financial...

    Provided By Universidade do Porto

  • White Papers // Jan 2011

    The Price Of Risk And Ambiguity In An Intertemporal General Equilibrium Model Of Asset Prices

    The authors consider a version of the intertemporal general equilibrium model of Cox et al. (1985a) with a single production process and two correlated state variables. It is assumed that only one of them, Y2, has shocks correlated with those of the economy's output rate and, simultaneously, that the representative...

    Provided By Universidade do Porto

  • White Papers // Jan 2011

    Improving the Performance of IEEE802.11s Networks Using Directional Antennas Over Multi-Radio/Multi-Channel Implementation - The Research Challenges

    The IEEE802.11s standard is a variety of Wireless Mesh Networks (WMNs), which features infrastructure-less flexible network configurations, is attracting attention as an elemental technology for future ubiquitous networks consisting of various types of nodes built on ad-hoc basis. To solve problems like throughput degradation, delay and fairness, an enhanced Medium...

    Provided By Universidade do Porto

  • White Papers // Dec 2010

    WiFIX+: A Multicast Solution for 802.11-Based Wireless Mesh Networks

    IEEE 802.11 is currently one of the main wireless technologies enabling ubiquitous Internet access. With the growing demand for wireless Internet access and the limited 802.11 radio range, 802.11-based Wireless Mesh Networks have been proposed as a flexible and cost-effective solution to extend the radio coverage of existing network infrastructures....

    Provided By Universidade do Porto

  • White Papers // Dec 2010

    Recent Trends In The Economics Of Innovation Literature Through The Lens Of Industrial And Corporate Change

    Paper on the economics of innovation has been in constant change. The authors quantitatively assess recent trends in this literature in terms of research topics and types of research. Departing from a comprehensive qualitative and quantitative survey of influential innovation handbooks, this paper draws on the review and analysis of...

    Provided By Universidade do Porto

  • White Papers // Nov 2010

    The Effects Of Foreign Direct Investment On The Host Country Economic Growth - Theory And Empirical Evidence

    Foreign Direct Investment (FDI) influences the host country's economic growth through the transfer of new technologies and know-how, formation of human resources, integration in global markets, increase of competition, and firms' development and reorganization. Empirically, a variety of studies considers that FDI generate economic growth in the host country. However,...

    Provided By Universidade do Porto

  • White Papers // Nov 2010

    The Level Of Human Capital In Innovative Firms Located In China. Is Foreign Capital Relevant?

    Studies on the impact of Foreign Direct Investment (FDI) on the Chinese economy have essentially focused on the relationship between FDI, productivity and economic growth, revealing a tendency toward sectoral and macroeconomic empirical studies. This work aims to complement these approaches and contribute to the rather limited literature on the...

    Provided By Universidade do Porto

  • White Papers // Oct 2010

    Core Patterns of Object-Oriented Meta-Architectures

    Meta-architectures, also known as reflective architectures, are a specific type of software architectures that are able to inspect their own structure and behavior, and dynamically adapt at runtime, thus responding to new user requirements or changes in their environment. In object-oriented programming, these architectures rely on a small set of...

    Provided By Universidade do Porto

  • White Papers // Oct 2010

    Is Human Capital Relevant In Attracting Innovative FDI To China?

    The impact of human capital on Foreign Direct Investment (FDI) has been assessed in an essentially descriptive manner. In general, most quantitative studies focus on the macroeconomic level, that is, the level of countries. Microeconomic studies, with firms as the unit of analysis, are scarce internationally and even more so...

    Provided By Universidade do Porto

  • White Papers // Jul 2010

    Trusted Storage Over Untrusted Networks

    The authors consider distributed storage over two untrusted networks, whereby coding is used as a means to achieve a prescribed level of confidentiality. The key idea is to exploit the algebraic structure of the Vandermonde matrix to mix the input blocks, before they are stored in different locations. The proposed...

    Provided By Universidade do Porto

  • White Papers // Jul 2010

    Inequality And Growth: Uncovering The Main Conclusions From The Empirics

    The theme of the relationship between inequality and economic growth has gained considerable attention among economists over the last two decades. In this paper, the authors analyse the effect of inequality on growth, whose related literature has been producing inconclusive results. After an exhaustive study of the major empirical works...

    Provided By Universidade do Porto

  • White Papers // Jul 2010

    Costly Investment, Complementarities, International Technological-Knowledge Diffusion And The Skill Premium

    The authors examine the behavior of the skill premium in a two-country general equilibrium growth model assuming technological-knowledge diffusion; internal costly investment in both physical capital and R&D; and complementarities between intermediate goods in production. They find that these three economic features affect the steady-state growth rate in both countries....

    Provided By Universidade do Porto

  • White Papers // May 2010

    Monetary And Fiscal Policy Interactions In A Monetary Union With Country-size Asymmetry

    This paper analyses optimal discretionary non-coordinated monetary and fiscal stabilization policies in a micro-founded New-Keynesian model of a two-country monetary union with country-size asymmetry, under two policy scenarios. A balanced-budget policy scenario and a policy scenario where the presence of government debt limits the macroeconomic stabilization effort and enlarges the...

    Provided By Universidade do Porto

  • White Papers // May 2010

    Practical Network Coding With Resilient Subspace Codes

    Network coding allows nodes in a network to combine different packets using linear operations. In most instances, the encoding coefficients are chosen randomly and placed in the packet header. The ability to correct errors and erasures is critical, because a single malicious packet injected by a misbehaving node or the...

    Provided By Universidade do Porto

  • White Papers // May 2010

    The Determinants Of Technology Transfer Efficiency And The Role Of Innovation Policies: A Survey

    The diversity found in the various Technology Transfer Offices (TTOs), besides being a consequence of the capacities and motives of the different stakeholders involved (public research organisations, industry, consulting firms and public authorities) also reflects the specificities of public incentives or policies and their differing degrees of commitment to technology...

    Provided By Universidade do Porto

  • White Papers // May 2010

    Economic Growth, Ecological Technology And Public Intervention

    Seminal works on growth theory had mainly focused on exogenous technological change, where a certain given path of technological change was considered. At the end of the 1980s, a new growth theory emerged allowing for the endogeneity of technological change, where economic agents can affect the pace of technological change...

    Provided By Universidade do Porto

  • White Papers // Apr 2010

    A Growth Model For The Quadruple Helix Innovation Theory

    The authors propose a theoretical growth model with which to frame analytically the Quadruple Helix Innovation Theory (QHIT). The aim is to emphasise the investment in innovation transmission mechanisms in terms of economic growth and productivity gains, in one-high-technology sector, by stressing the role played by the helices of the...

    Provided By Universidade do Porto

  • White Papers // Mar 2010

    Home Country Trade Effects Of Outward FDI: An Analysis Of The Portuguese Case, 1996-2007

    Given the increased internationalisation of the Portuguese economy through outward Foreign Direct Investment (FDI), particularly on the Portuguese-speaking countries, the main objective is to discuss the empirical relationship between this outward FDI and trade. The authors use panel data analysis within a framework of gravity equations for exports and imports,...

    Provided By Universidade do Porto

  • White Papers // Nov 2009

    Geographic Oil Concentration And Economic Growth ? A Panel Data Analysis

    Given a panel of oil producing countries, the authors show that a higher oil concentration is associated with an increase in economic growth through capital efficiency in: countries with medium and low income per head from East Asia & Pacific and Latin America & the Caribbean, classified as followers in...

    Provided By Universidade do Porto

  • White Papers // Sep 2009

    Analyzing the Impact of Real and Non-Real Time Traffic on Joint Radio Resource Management

    The joint management of radio resources from different network technologies gains an increasing importance when a crescent number of heterogeneous networks are interconnected. From the user's point of view, those networks are seen as a single broad access network, while for the telecommunications operator this joint management approach improves the...

    Provided By Universidade do Porto

  • White Papers // Sep 2009

    WiFIX: A New Solution for 802.11-Based Wireless Mesh Networks

    Ubiquitous Internet access is becoming crucial for end-users due to the increasing number of services and applications supported over the Internet. Extending the coverage of current Wi-Fi infrastructures installed in companies, universities, and cities, has been considered a solution to help in fulfilling this requirement, namely when it comes to...

    Provided By Universidade do Porto

  • White Papers // Jul 2009

    Performance Analysis of Joint Radio Resource Management Strategies for Beyond 3G Networks

    In beyond 3G networks the user will not be aware of the access network technology used to provide a telecommunications service. Heterogeneous network technologies will be seamlessly integrated in one "Common" access network, enabling users to move around and continuously receive their subscribed services. In a commercial environment, this network...

    Provided By Universidade do Porto

  • White Papers // Jun 2009

    Management of User Generated Multicast Sessions in IMS-Based Networks

    Factors such as the growing number of multimedia terminals, the constant increase of bandwidth available per user, and the large number of existing data sharing applications, are compelling users to generate and distribute their own content to restricted groups of other users. Inorder to support such scenario, the authors present...

    Provided By Universidade do Porto

  • White Papers // Apr 2009

    Costly Investment, Complementarities And The Skill Premium

    The authors propose a new framework to analyze the wage premium behavior. Building on Acemoglu and Zilibotti (2001), they introduce physical capital and two assumptions: internal costly investment in both capital and R&D; complementarities between capital goods in production. They find that, for economies relatively abundant in high-skilled labour, a...

    Provided By Universidade do Porto

  • White Papers // Feb 2009

    Network Effects In A Human Capital Based Economic Growth Model

    Recent theoretical macroeconomic growth models emphasize the ultimate sources of growth. In these so called 'Endogenous growth models', the long-run rate of growth depends on a set of parameters that describe some inner characteristics of the economy. These characteristics may be connected to preferences (e. g. the relative importance of...

    Provided By Universidade do Porto

  • White Papers // Feb 2009

    Towards the Optimization of Video P2P Streaming Over Wireless Mesh Networks

    P2P overlay networks are large-scale distributed systems. They are used mainly for data sharing and content distribution and can be more efficient than the traditional client-server data models. On the other hand, emerging Mesh networks are effective solutions for ubiquitous broadband access. High throughput, cost effectiveness, and ease of deployment...

    Provided By Universidade do Porto

  • White Papers // Jan 2009

    Effective Delay Control in Online Network Coding

    Motivated by streaming applications with stringent delay constraints, the authors consider the design of online network coding algorithms with timely delivery guarantees. Assuming that the sender is providing the same data to multiple receivers over independent packet erasure channels, they focus on the case of perfect feedback and heterogeneous erasure...

    Provided By Universidade do Porto

  • White Papers // Sep 2008

    The Impact Of FDI, Cross Border Mergers And Acquisitions And Greenfield Investments On Economic Growth

    This paper investigates whether aggregate Foreign Direct Investment (FDI), cross border Mergers and Acquisitions (M&A) and greenfield investments affects economic growth based on a panel data of 53 countries over the period 1996-2006. Both causality tests and single growth equations are applied to examine this relationship. The evidence suggests that...

    Provided By Universidade do Porto

  • White Papers // Jun 2008

    SMIz - Secure Multicast IPTV With Efficient Support for Video Channel Zapping

    The current trend in technological evolution is leading telecommunications to all-IP network scenarios, where multiple services are transported as IP packets. Among these are the services based in group communications over IP with confidentiality requirements. Secure IP multicast may be used for the secure broadcasting of multiple video channels over...

    Provided By Universidade do Porto

  • White Papers // Jun 2008

    The Macroeconomic Determinants Of Cross Border Mergers And Acquisitions And Greenfield Investments

    When a company decides to invest abroad, it can do it through the establishment of a new firm (greenfield investment) or by the purchase of an already existing firm. Although there is a vast empirical literature on the macroeconomic determinants of aggregate FDI, there are just a few studies examining...

    Provided By Universidade do Porto

  • White Papers // May 2008

    Stylized Facts And Other Empirical Evidence On Firm Dynamics, Business Cycle And Growth

    In this paper, the authors bring together in a systematised fashion the scattered empirical evidence relating firm dynamics and both short-run and long-run macroeconomic dynamics. There are numerous studies that focus on firm-level data while controlling for macroeconomic conditions, which cover a considerable range of variables, industries and countries. From...

    Provided By Universidade do Porto

  • White Papers // Jan 2009

    Effective Delay Control in Online Network Coding

    Motivated by streaming applications with stringent delay constraints, the authors consider the design of online network coding algorithms with timely delivery guarantees. Assuming that the sender is providing the same data to multiple receivers over independent packet erasure channels, they focus on the case of perfect feedback and heterogeneous erasure...

    Provided By Universidade do Porto

  • White Papers // Mar 2010

    Home Country Trade Effects Of Outward FDI: An Analysis Of The Portuguese Case, 1996-2007

    Given the increased internationalisation of the Portuguese economy through outward Foreign Direct Investment (FDI), particularly on the Portuguese-speaking countries, the main objective is to discuss the empirical relationship between this outward FDI and trade. The authors use panel data analysis within a framework of gravity equations for exports and imports,...

    Provided By Universidade do Porto

  • White Papers // Apr 2010

    A Growth Model For The Quadruple Helix Innovation Theory

    The authors propose a theoretical growth model with which to frame analytically the Quadruple Helix Innovation Theory (QHIT). The aim is to emphasise the investment in innovation transmission mechanisms in terms of economic growth and productivity gains, in one-high-technology sector, by stressing the role played by the helices of the...

    Provided By Universidade do Porto

  • White Papers // May 2010

    The Determinants Of Technology Transfer Efficiency And The Role Of Innovation Policies: A Survey

    The diversity found in the various Technology Transfer Offices (TTOs), besides being a consequence of the capacities and motives of the different stakeholders involved (public research organisations, industry, consulting firms and public authorities) also reflects the specificities of public incentives or policies and their differing degrees of commitment to technology...

    Provided By Universidade do Porto

  • White Papers // Jul 2010

    Inequality And Growth: Uncovering The Main Conclusions From The Empirics

    The theme of the relationship between inequality and economic growth has gained considerable attention among economists over the last two decades. In this paper, the authors analyse the effect of inequality on growth, whose related literature has been producing inconclusive results. After an exhaustive study of the major empirical works...

    Provided By Universidade do Porto

  • White Papers // Jul 2010

    Costly Investment, Complementarities, International Technological-Knowledge Diffusion And The Skill Premium

    The authors examine the behavior of the skill premium in a two-country general equilibrium growth model assuming technological-knowledge diffusion; internal costly investment in both physical capital and R&D; and complementarities between intermediate goods in production. They find that these three economic features affect the steady-state growth rate in both countries....

    Provided By Universidade do Porto

  • White Papers // Nov 2010

    The Effects Of Foreign Direct Investment On The Host Country Economic Growth - Theory And Empirical Evidence

    Foreign Direct Investment (FDI) influences the host country's economic growth through the transfer of new technologies and know-how, formation of human resources, integration in global markets, increase of competition, and firms' development and reorganization. Empirically, a variety of studies considers that FDI generate economic growth in the host country. However,...

    Provided By Universidade do Porto

  • White Papers // Oct 2010

    Is Human Capital Relevant In Attracting Innovative FDI To China?

    The impact of human capital on Foreign Direct Investment (FDI) has been assessed in an essentially descriptive manner. In general, most quantitative studies focus on the macroeconomic level, that is, the level of countries. Microeconomic studies, with firms as the unit of analysis, are scarce internationally and even more so...

    Provided By Universidade do Porto

  • White Papers // Nov 2010

    The Level Of Human Capital In Innovative Firms Located In China. Is Foreign Capital Relevant?

    Studies on the impact of Foreign Direct Investment (FDI) on the Chinese economy have essentially focused on the relationship between FDI, productivity and economic growth, revealing a tendency toward sectoral and macroeconomic empirical studies. This work aims to complement these approaches and contribute to the rather limited literature on the...

    Provided By Universidade do Porto

  • White Papers // Dec 2010

    Recent Trends In The Economics Of Innovation Literature Through The Lens Of Industrial And Corporate Change

    Paper on the economics of innovation has been in constant change. The authors quantitatively assess recent trends in this literature in terms of research topics and types of research. Departing from a comprehensive qualitative and quantitative survey of influential innovation handbooks, this paper draws on the review and analysis of...

    Provided By Universidade do Porto

  • White Papers // Jan 2011

    The Price Of Risk And Ambiguity In An Intertemporal General Equilibrium Model Of Asset Prices

    The authors consider a version of the intertemporal general equilibrium model of Cox et al. (1985a) with a single production process and two correlated state variables. It is assumed that only one of them, Y2, has shocks correlated with those of the economy's output rate and, simultaneously, that the representative...

    Provided By Universidade do Porto

  • White Papers // Feb 2011

    Financial Constraints And Exports: Evidence From Portuguese Manufacturing Firms

    This paper analyzes the links between financial constraints and firm export behavior, at the firm level, by using data on Portuguese manufacturing enterprises. Theoretical models of Chaney (2005) and Manova (2010) suggest that credit constraints are detrimental for exports but no model explains consistently why exports could improve firms? financial...

    Provided By Universidade do Porto

  • White Papers // May 2008

    Stylized Facts And Other Empirical Evidence On Firm Dynamics, Business Cycle And Growth

    In this paper, the authors bring together in a systematised fashion the scattered empirical evidence relating firm dynamics and both short-run and long-run macroeconomic dynamics. There are numerous studies that focus on firm-level data while controlling for macroeconomic conditions, which cover a considerable range of variables, industries and countries. From...

    Provided By Universidade do Porto

  • White Papers // Jun 2008

    The Macroeconomic Determinants Of Cross Border Mergers And Acquisitions And Greenfield Investments

    When a company decides to invest abroad, it can do it through the establishment of a new firm (greenfield investment) or by the purchase of an already existing firm. Although there is a vast empirical literature on the macroeconomic determinants of aggregate FDI, there are just a few studies examining...

    Provided By Universidade do Porto

  • White Papers // Feb 2009

    Network Effects In A Human Capital Based Economic Growth Model

    Recent theoretical macroeconomic growth models emphasize the ultimate sources of growth. In these so called 'Endogenous growth models', the long-run rate of growth depends on a set of parameters that describe some inner characteristics of the economy. These characteristics may be connected to preferences (e. g. the relative importance of...

    Provided By Universidade do Porto

  • White Papers // May 2010

    Economic Growth, Ecological Technology And Public Intervention

    Seminal works on growth theory had mainly focused on exogenous technological change, where a certain given path of technological change was considered. At the end of the 1980s, a new growth theory emerged allowing for the endogeneity of technological change, where economic agents can affect the pace of technological change...

    Provided By Universidade do Porto

  • White Papers // Nov 2009

    Geographic Oil Concentration And Economic Growth ? A Panel Data Analysis

    Given a panel of oil producing countries, the authors show that a higher oil concentration is associated with an increase in economic growth through capital efficiency in: countries with medium and low income per head from East Asia & Pacific and Latin America & the Caribbean, classified as followers in...

    Provided By Universidade do Porto

  • White Papers // Sep 2008

    The Impact Of FDI, Cross Border Mergers And Acquisitions And Greenfield Investments On Economic Growth

    This paper investigates whether aggregate Foreign Direct Investment (FDI), cross border Mergers and Acquisitions (M&A) and greenfield investments affects economic growth based on a panel data of 53 countries over the period 1996-2006. Both causality tests and single growth equations are applied to examine this relationship. The evidence suggests that...

    Provided By Universidade do Porto

  • White Papers // Feb 2011

    Universities And Authors: A Ranking For International Finance

    The authors rank universities and colleges and they list the top 100 authors in the sub-field of International Finance using the EconLit database and measuring quality by the number of American Economic Review-equivalent articles published over the ten-year period 1996-2005. They observe that there is some dissimilarity between the ranking...

    Provided By Universidade do Porto

  • White Papers // Jun 2011

    Lumpy Investment In Sticky Information General Equilibrium

    This paper introduces lumpy micro-level investment into a sticky information general equilibrium model. Lumpy investment arises because of inattentiveness in capital investment decisions instead of the more popular assumption of non-convex adjustment costs. Sticky information is the only source of rigidity in the model and it is pervasive to all...

    Provided By Universidade do Porto

  • White Papers // Apr 2009

    Costly Investment, Complementarities And The Skill Premium

    The authors propose a new framework to analyze the wage premium behavior. Building on Acemoglu and Zilibotti (2001), they introduce physical capital and two assumptions: internal costly investment in both capital and R&D; complementarities between capital goods in production. They find that, for economies relatively abundant in high-skilled labour, a...

    Provided By Universidade do Porto

  • White Papers // May 2010

    Monetary And Fiscal Policy Interactions In A Monetary Union With Country-size Asymmetry

    This paper analyses optimal discretionary non-coordinated monetary and fiscal stabilization policies in a micro-founded New-Keynesian model of a two-country monetary union with country-size asymmetry, under two policy scenarios. A balanced-budget policy scenario and a policy scenario where the presence of government debt limits the macroeconomic stabilization effort and enlarges the...

    Provided By Universidade do Porto

  • White Papers // Jul 2011

    Macroeconomic Effects Of Fiscal Consolidations In A DSGE Model For The Euro Area: Does Composition Matter?

    The authors develop a new-Keynesian DSGE model with an extended fiscal policy block to assess the conditions for expansionary fiscal consolidations. In addition to several taxes, they consider public employment expenditures and government spending, which may have different degrees of productivity. They calibrate the model for the Euro Area and...

    Provided By Universidade do Porto

  • White Papers // May 2010

    Practical Network Coding With Resilient Subspace Codes

    Network coding allows nodes in a network to combine different packets using linear operations. In most instances, the encoding coefficients are chosen randomly and placed in the packet header. The ability to correct errors and erasures is critical, because a single malicious packet injected by a misbehaving node or the...

    Provided By Universidade do Porto

  • White Papers // Dec 2010

    WiFIX+: A Multicast Solution for 802.11-Based Wireless Mesh Networks

    IEEE 802.11 is currently one of the main wireless technologies enabling ubiquitous Internet access. With the growing demand for wireless Internet access and the limited 802.11 radio range, 802.11-based Wireless Mesh Networks have been proposed as a flexible and cost-effective solution to extend the radio coverage of existing network infrastructures....

    Provided By Universidade do Porto

  • White Papers // Sep 2009

    WiFIX: A New Solution for 802.11-Based Wireless Mesh Networks

    Ubiquitous Internet access is becoming crucial for end-users due to the increasing number of services and applications supported over the Internet. Extending the coverage of current Wi-Fi infrastructures installed in companies, universities, and cities, has been considered a solution to help in fulfilling this requirement, namely when it comes to...

    Provided By Universidade do Porto

  • White Papers // Sep 2009

    Analyzing the Impact of Real and Non-Real Time Traffic on Joint Radio Resource Management

    The joint management of radio resources from different network technologies gains an increasing importance when a crescent number of heterogeneous networks are interconnected. From the user's point of view, those networks are seen as a single broad access network, while for the telecommunications operator this joint management approach improves the...

    Provided By Universidade do Porto

  • White Papers // Jul 2009

    Performance Analysis of Joint Radio Resource Management Strategies for Beyond 3G Networks

    In beyond 3G networks the user will not be aware of the access network technology used to provide a telecommunications service. Heterogeneous network technologies will be seamlessly integrated in one "Common" access network, enabling users to move around and continuously receive their subscribed services. In a commercial environment, this network...

    Provided By Universidade do Porto

  • White Papers // Jun 2009

    Management of User Generated Multicast Sessions in IMS-Based Networks

    Factors such as the growing number of multimedia terminals, the constant increase of bandwidth available per user, and the large number of existing data sharing applications, are compelling users to generate and distribute their own content to restricted groups of other users. Inorder to support such scenario, the authors present...

    Provided By Universidade do Porto

  • White Papers // Jan 2011

    Improving the Performance of IEEE802.11s Networks Using Directional Antennas Over Multi-Radio/Multi-Channel Implementation - The Research Challenges

    The IEEE802.11s standard is a variety of Wireless Mesh Networks (WMNs), which features infrastructure-less flexible network configurations, is attracting attention as an elemental technology for future ubiquitous networks consisting of various types of nodes built on ad-hoc basis. To solve problems like throughput degradation, delay and fairness, an enhanced Medium...

    Provided By Universidade do Porto

  • White Papers // Feb 2009

    Towards the Optimization of Video P2P Streaming Over Wireless Mesh Networks

    P2P overlay networks are large-scale distributed systems. They are used mainly for data sharing and content distribution and can be more efficient than the traditional client-server data models. On the other hand, emerging Mesh networks are effective solutions for ubiquitous broadband access. High throughput, cost effectiveness, and ease of deployment...

    Provided By Universidade do Porto

  • White Papers // Jun 2008

    SMIz - Secure Multicast IPTV With Efficient Support for Video Channel Zapping

    The current trend in technological evolution is leading telecommunications to all-IP network scenarios, where multiple services are transported as IP packets. Among these are the services based in group communications over IP with confidentiality requirements. Secure IP multicast may be used for the secure broadcasting of multiple video channels over...

    Provided By Universidade do Porto

  • White Papers // Mar 2011

    Position-Based Jamming for Enhanced Wireless Secrecy

    Signal interference and packet collisions are typically viewed as negative factors that hinder wireless communication networks. When security is the primary concern, signal interference may actually be very helpful. Starting with a stochastic network model, the authors are able to show that packet collisions caused by jamming nodes can indeed...

    Provided By Universidade do Porto

  • White Papers // Mar 2011

    Jammer Selection Policies for Secure Wireless Networks

    The authors consider a wireless network scenario in which the communicating nodes are assisted by a number of jammers. The goal of the jammers is to obstruct potential eavesdroppers while restricting the harmful interference experienced by the legitimate receiver. Based on a stochastic network model, they are able to show...

    Provided By Universidade do Porto

  • White Papers // Mar 2011

    Friendly Jamming for Wireless Secrecy

    The authors analyze the role of jamming as a means to increase the security of wireless systems. Specifically, they characterize the impact of cooperative/friendly jamming on the secrecy outage probability of a quasi-static wiretap fading channel. They introduce jamming coverage and jamming efficiency as security metrics, and evaluate the performance...

    Provided By Universidade do Porto

  • White Papers // Oct 2010

    Core Patterns of Object-Oriented Meta-Architectures

    Meta-architectures, also known as reflective architectures, are a specific type of software architectures that are able to inspect their own structure and behavior, and dynamically adapt at runtime, thus responding to new user requirements or changes in their environment. In object-oriented programming, these architectures rely on a small set of...

    Provided By Universidade do Porto

  • White Papers // Mar 2012

    Systematic Network Coding With the Aid of a Full-Duplex Relay

    A characterization of systematic network coding over multi-hop wireless networks is key towards understanding the trade-off between complexity and delay performance of networks that preserve the systematic structure. This paper studies the case of a relay channel, where the source's objective is to deliver a given number of data packets...

    Provided By Universidade do Porto

  • White Papers // Jul 2010

    Trusted Storage Over Untrusted Networks

    The authors consider distributed storage over two untrusted networks, whereby coding is used as a means to achieve a prescribed level of confidentiality. The key idea is to exploit the algebraic structure of the Vandermonde matrix to mix the input blocks, before they are stored in different locations. The proposed...

    Provided By Universidade do Porto