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An effective algorithm for obtaining the minimal cost pair of disjoint paths with dual arc costs

Gomes, Teresa; Craveirinha, José; Jorge, Luísa
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.41%
Routing optimisation in some types of networks requires the calculation of the minimal cost pair of disjoint paths such that the cost functions associated with the arcs in the two paths are different. An exact algorithm for solving this NP-complete problem is proposed, based on a condition which guarantees that the optimal path pair cost has been obtained. This optimality condition is based on the calculation of upper and lower bounds on the optimal cost. A formal proof of the correctness of the algorithm is described. Extensive experimentation is presented to show the effectiveness of the algorithm, including a comparison with an integer linear programming formulation.

An effective algorithm for obtaining the whole set of minimal cost pairs of disjoint paths with dual arc costs

Gomes, Teresa; Craveirinha, José; Jorge, Luísa
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.43%
In telecommunication networks design the problem of obtaining optimal (arc or node) disjoint paths, for increasing network reliability, is extremely important. The problem of calculating kc disjoint paths from s to t (two distinct nodes), in a network with kc different (arbitrary) costs on every arc such that the total cost of the paths is minimised, is NP-complete even for kc = 2. When kc = 2 these networks are usually designated as dual arc cost networks. In this paper we propose an exact algorithm for finding the whole set of arc-disjoint path pairs, with minimal cost in a network with dual arc costs. The correctness of the algorithm is based on a condition which guarantees that the optimal path pair cost has been obtained and on a proposition which guarantees that at the end of the algorithm all the optimal pairs have been obtained. The optimality condition is based on the calculation of upper and lower bounds on the optimal cost. Extensive experimentation is presented to show the effectiveness of the algorithm.

An effective algorithm for obtaining the minimal cost pair of disjoint paths with dual arc costs

Gomes, Teresa; Craveirinha, José; Jorge, Luí­sa
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
45.41%
Routing optimisation in some types of networks requires the calculation of the minimal cost pair of disjoint paths such that the cost functions associated with the arcs in the two paths are different. An exact algorithm for solving this NP-complete problem is proposed, based on a condition which guarantees that the optimal path pair cost has been obtained. This optimality condition is based on the calculation of upper and lower bounds on the optimal cost. A formal proof of the correctness of the algorithm is described. Extensive experimentation is presented to show the effectiveness of the algorithm, including a comparison with an integer linear programming formulation.; http://www.sciencedirect.com/science/article/B6VC5-4S7BDKX-2/1/f8493f6260218c44c9894cdd57455511

Efficient calculation of the most reliable pair of link disjoint paths in telecommunication networks

Gomes, Teresa; Craveirinha, José
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
55.4%
In transmission networks an important routing problem is to find a pair of link disjoint paths which optimises some performance measure. In this paper the problem of obtaining the most reliable pair of link disjoint paths, assuming the reliability of the links are known, is considered. This is a non-linear optimisation problem. It is further introduced the constraint that the length of the paths should not exceed a certain number of links, which makes the efficient resolution of the problem more complex.; http://www.sciencedirect.com/science/article/B6VCT-4JS20BJ-2/1/d3a0679a9c65e51ae2074080f957df94

Convergência digital e a telefonia móvel: implicações à gestão estratégica e à inovação.; Digital convergence and mobile telecommunications: Implications toward strategic management and innovation.

Frontini, Maria Alice Braga
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/04/2008 PT
Relevância na Pesquisa
45.8%
O setor de telecomunicações, mundial e brasileiro, vive um momento de pressão por rentabilidade e competitividade das empresas. Adicionalmente, a variedade de soluções tecnológicas traz incertezas quanto à adoção dos usuários às novas tecnologias e à identificação e implantação de modelos de negócios sustentáveis. Esta pressão por competitividade leva as operadoras a adotarem uma atitude de liderança perante a inovação, objetivando a diferenciação e manutenção das margens. Um dos elementos diferenciadores das operadoras móveis está situado na inovação decorrente da convergência digital, entre as tecnologias de redes de comunicação, de processamento e de apresentação das informações. Apesar da convergência digital existir tecnologicamente desde a década de 60 com o advento do protocolo TCP/IP, é atualmente que se observa o surgimento de novos modelos de negócios e de produtos e serviços convergentes, baseados em novos atributos de valor fornecidos ao consumidor final. Nesta conjuntura de elevada competitividade e incerteza, julga-se relevante que as iniciativas estratégicas relativa à inovação sejam adequadamente geridas, especificamente aquelas referentes à convergência digital, para que se tornem elementos diferenciadores e sustentadores da competitividade empresarial. A pesquisa em questão visa identificar e analisar os impactos na gestão estratégica orientada à inovação...

Empowering the bottom of the pyramid - an analysis of an investment cooperation in Angola: the case of ONI Communications

Fartaria, Marina Sofia Crespo
Fonte: Instituto Universitário de Lisboa Publicador: Instituto Universitário de Lisboa
Tipo: Dissertação de Mestrado
Publicado em //2010 ENG
Relevância na Pesquisa
45.43%
Master in International Management / JEL Classification: F23 - Multinational Firms; International Business; O1 - Economic Development; The purpose of this thesis is to develop a business model for companies that do foresee the Bottom of the Pyramid (BoP) as a promising and challenging market, that can enhance their position in the competitive context. According to Prahalad’s definition, ―world’s 4 billion poor, people who live on far less than $2 a day‖, are located at the BoP (Prahalad & Hart, first quarter 2002). Angola, the target market of this study, is one of the world’s poorest countries and one the fastest growing economies. It started reinventing itself economically and politically, after the end of the civil war in 2002, creating the right conditions for companies to invest. Angola attracted since 2003 over 1.124 projects representing more than USD 4 billion in investment capital. This study describes the benefits Angola, as fast growing economy, brings to foreign investors and the many advantages it presents mostly to Portuguese companies due to its long-relationship with Portugal. Doing business in Angola can lead to an indirect development of other sectors, welfare increase and competition. Based on the experience of ONI Communications in vertical solutions...

Entry, Investment and Competition in Telecommunications and Media Markets

Balmer, Roberto
Fonte: La Sapienza Universidade de Roma Publicador: La Sapienza Universidade de Roma
Tipo: Tese de Doutorado
EN
Relevância na Pesquisa
55.69%
This Ph.D. thesis builds on the new empirical industrial organization (NEIO) literature trying to use market data to determine fundamental market drivers such as demand parameters, entry and investment thresholds or the level and development of competition in the market. The thesis addresses two sectors: telecommunications (high-speed internet as well as fixed telephony) and media (newspaper sellers). It is divided in three articles 1) Geographic regulation and cooperative investment in next generation broadband networks A review of recent literature and practical cases This article reviews the theoretical and empirical literature on geographic regulation and co-investments in next generation broadband. Alternative telecom operators have continuously invested in their own infrastructure in recent years. After more than a decade since liberalisation, competitive conditions have substantially changed, especially in urban areas. European regulatory authorities have acknowledged this development by starting regional deregulation. Additionally, different forms of cooperative investments in next generation broadband have appeared on the market. The effects of such schemes on competition, investment and welfare crucially depend on the fine details of implementation. For instance...

Broadband Infrastructure Investment in Stimulus Packages : Relevance for Developing Countries

Qiang, Christine Zhen-Wei
Fonte: Banco Mundial Publicador: Banco Mundial
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.53%
Reviewing a dozen of fiscal stimulus packages in developed countries, this paper analyzes one common strategy that has found widespread support in these stimulus packages and its relevance for developing countries: investing in broadband and next-generation networks, as a counter-cyclical tool to create jobs and provide the foundation for economic recovery and long-term sustained growth. The paper looks at the various impacts broadband investment is expected to have: short-term job creation and aggregate demand effects, and long-term productive activities in other sectors of the economy. Moreover, broadband investment is more fiscally sound than other public spending stimulus options, in the sense of coming closer to, or in some cases actually being, self-financing. Several factors highlight the potential of broadband infrastructure as an important area of public investment during economic downturn, an option also open to policymakers in developing countries. Spending initiatives on next-generation telecommunications networks at a time when labor market conditions are particularly weak can help preserve jobs and head off a potential burden on social safety nets. Bringing forward longer-term aggregate spillover effects of broadband can improve the productivity of the entire economy and is consistent with enhancing longer-run growth and development. Public support also "crowds in" private investment when access to private financing is decreasing and more expensive.

Services in a Development Round : Three Goals and Three Proposals

Mattoo, Aaditya
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Relevância na Pesquisa
45.53%
The benefits of services trade reform are huge but services negotiations in the World Trade Organization (WTO) are making little progress. A proximate cause is the current negotiating process, based on an inertial request-and-offer approach rather than a set of goals that would give direction and momentum to the negotiations. The paper suggests that WTO members should consider: (1) locking in the current openness of cross-border trade for a wide range of services; (2) eliminating barriers to foreign investment either immediately or in a phased manner where regulatory inadequacies need to be remedied; and (3) allowing greater freedom of international movement at least for intra-corporate transferees and for service providers to fulfill specific services contracts. A deeper problem is that WTO members have sought to negotiate market access in services without adequately addressing concerns that the General Agreement on Trade in Services (GATS) commitments limit regulatory freedom unduly and unpredictably, that regulatory institutions in many countries are too weak to cope with liberalized markets, and that there is no provision for the regulatory cooperation that is necessary for successful liberalization, particularly of temporary labor mobility. Three types of actions are needed: (1) at the current stage of its development...

Capacity Enhancement at the Institutional Level : Three Case Studies in Telecommunications

Wilhelm, Vera; Mueller, Susanne D.
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Relevância na Pesquisa
45.61%
How can the Bank or other development agencies more effectively support capacity enhancement (CE) in client countries? Is there a more systematic way to design and track capacity enhancement activities? Experience in telecom reform in Mali, Mauritania, and Morocco provides insights into the different opportunities and constraints that different countries face in implementing very similar reforms. It forms the basis for proposing a three-way framework for analyzing needs and planning capacity enhancement assistance.

Private Activity in Telecommunications Recovered in 2010 But Remained Below Pre-Financial Crisis Levels

Jett, Alexander Nicholas
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Relevância na Pesquisa
45.68%
In 2010, eight new telecom projects with private participation reached financial or contractual closure in seven low and middle income countries. These projects involved investment commitments of US$4.2 billion. Telecommunications projects implemented in the 1990-2009 period attracted new investment of US$67 billion, bringing total investment commitments to the sector to US$71.2 billion in 2010. Total investment in the sector grew by 15 percent in 2010 compared with 2009, recovering from the sharp drop in 2009, but remained below the pre-financial crisis levels of 2007-08. The number of new projects reaching financial closure (eight) was the lowest of the entire period of 1990-2010), suggesting that activity in most countries focused on network expansion of existing operators rather than increasing the number of operators. Certainly, telecommunications operators in many developing countries have merged or consolidated in the last few years.

Private Participation in Telecommunications : Recent Trends

Izaguirre, Ada Karina
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Relevância na Pesquisa
45.76%
More than ninety developing economies opened their telecommunications sector to private participation between 1990 and 1998. These countries transferred to the private sector the operating or construction risk, or both, of more than 500 projects, attracting investment commitments of US$214 billion. Two-thirds of that amount has been invested in expanding and modernizing networks; the other third has gone to governments as divestiture revenues or license fees. The investment shows three main trends: Latin America is in the lead. Private participation takes place in increasingly competitive market structures. And divestitures and greenfield projects outnumber operations and management contracts.

Mitigating Regulatory Risk in Telecommunications

Smith, Peter L.; Wellenius, Bjorn
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Relevância na Pesquisa
55.75%
In the transition from state-owned monopolies to privately led and increasingly competitive market structures in telecommunications, poor performance of regulatory agencies limits the benefits of reform. This Note proposes measures for establishing a regulatory framework that enables better sector performance even when a full-fledged regulatory agency is lacking. These measures reduce the need for agency decisions -- for example, by prepackaging rules and accelerating competition. They enhance the credibility of regulation -- for example, by locking in principles through international agreements. And they generate maximum impact from scarce professional and financial resources by using them effectively -- such as by contracting out functions and creating multisectoral or regional agencies.

ADR in B2B disputes in the EU telecommunications sector : where does the EU stand and what does the EU stand for?

WARWAS, Barbara Alicja
Fonte: Instituto Universitário Europeu Publicador: Instituto Universitário Europeu
Tipo: Trabalho em Andamento Formato: application/pdf; digital
EN
Relevância na Pesquisa
45.73%
This paper analyses the application of alternative dispute resolution (ADR) mechanisms to disputes arising between telecommunications undertakings under the EU Telecommunications Package, as revised on November 4, 2009. The new rules aimed at facilitating the development of the EU common telecommunications market, and were designed to increase the powers of national regulatory authorities (NRAs) across the Member States in the imposition of regulatory obligations in a coherent manner. One key reform concerned the centralisation of the dispute resolution functions of NRAs. Within the new dispute resolution prerogatives, NRAs were empowered with a right to determine their appropriateness for handling regulatory disputes between telecommunications undertakings or to decline their jurisdiction should other ADR means be available and more suitable for the resolution of regulatory disputes. This paper examines the mere development of ADR in telecommunications disputes in the UK, Ireland and Poland following the revision of the EU Telecommunications Package. Moreover, the paper analyses the effectiveness of the recent European Union (EU) policy on promoting ADR within the EU legal order against the background of the fragmented national approaches to ADR...

Is market-oriented reform producing a "two-track" Europe? Evidence from electricity and telecommunications; ¿Están generando las reformas orientadas hacia el mercado una Europa de “dos velocidades”? Evidencia para los casos de la electricidad y las telecomunicaciones

Clifton, Judith Catherine; Díaz Fuentes, Daniel; Fernández Gutiérrez, Marcos; Revuelta López, Julio
Fonte: MPRA Publicador: MPRA
Tipo: info:eu-repo/semantics/workingPaper; publishedVersion
ENG
Relevância na Pesquisa
45.65%
ABTRACT. The European Commission has formally recognised that adequate provision of basic household services, including energy, communications, water and transport, is key to ensuring equity, social cohesion and solidarity. Yet little research has been done on the impact of the reform of these services in this regard. This article offers an innovative way to explore such questions by analysing and contrasting stated and revealed preferences on citizen satisfaction with and expenditure on two services, electricity and telecommunications, in two large countries, Spain and the United Kingdom. In telecommunications, but to a much lesser extent in electricity, we find evidence that reform has led to a “two-track” Europe, where citizens who are elderly, not working or the less-educated behave differently in the market, with the result that they are less satisfied with these services than their younger, working, better-educated, counterparts.; RESUMEN. La Comisión Europea ha establecido que la adecuada provisión de servicios básicos para los hogares, tales como la energía, las telecomunicaciones, el agua y el transporte, es clave para garantizar la equidad, la cohesión social y la solidaridad. Sin embargo, son escasas las investigaciones que han analizado el impacto de las reformas de estos servicios focalizando en dichos aspectos. Este artículo ofrece una aproximación innovadora para explorar estas cuestiones...

Access Regulation, Entry, and Investment in Telecommunications

MANENTI, Fabio; SCIALÀ, Antonio
Fonte: Instituto Universitário Europeu Publicador: Instituto Universitário Europeu
Tipo: Trabalho em Andamento Formato: application/pdf
EN
Relevância na Pesquisa
55.61%
This paper presents a model of competition between an incumbent and an entrant firm in telecommunications. The entrant has the option to enter the market with or without having preliminary invested in its own infrastructure; in case of facility based entry, the entrant has also the option to invest in the provision of enhanced services. In case of resale based entry the entrant needs access to the incumbent network. Unlike the rival, the incumbent has always the option to upgrade the existing network to provide advanced services. We study the impact of access regulation on the type of entry and on firms' investments. Without regulation, we find that the incumbent sets the access charge to prevent resale based entry and this overstimulates rival's investment that may turn out to be socially inefficient. Access regulation may discourage welfare enhancing investments, thus also inducing a socially inefficient outcome. We extend the model to account for negotiated interconnection in case of facilities based entry.

Private Telecom Projects : Private Activity Down 15 Percent in 2003

Izaguirre, Ada Karina
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Viewpoint; Publications & Research
ENGLISH
Relevância na Pesquisa
45.6%
Drawing on the World Bank's private participation in infrastructure project database, this note reviews developments in the telecommunications sector in 2003. Data for the year show that investment in projects with private participation was back to 1996 levels. Two regions -the Middle East and North Africa and Europe and Central Asia-saw private activity grow in 2003. And developing country companies were the most active sponsors. Private activity in telecommunications in low and middle-income countries remained subdued in 2003. Investment flows to projects with private participation declined for the third consecutive year, amounting to US$28.5 billion. Nevertheless, 22 new projects with fixed or mobile operators reached financial closure in 16 developing countries. Most of the decline in investment occurred in lower-middle-income countries, where investment flows dropped from US$11.3 billion to US$8.8 billion. Low-income countries also contributed to the slowdown, with investment flows falling from US$6.8 billion to US$5.4 billion. Flows were nevertheless strong...

Are Cost Models Useful for Telecoms Regulators in Developing Countries?

Benitez, Daniel A.; Estache, Antonio; Kennet, D. Mark; Ruzzier, Christian A.
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research; Publications & Research :: Policy Research Working Paper
EN_US
Relevância na Pesquisa
45.68%
Worldwide privatization of the telecommunications industry, and the introduction of competition in the sector, together with the ever-increasing rate of technological advance in telecommunications, raise new and critical challenges for regulation. Fo matters of pricing, universal service obligations, and the like, one question to be answered is this: What is the efficient cost of providing the service to a certain area or type of customer? As developing countries build up their capacity to regulate their privatized infrastructure monopolies, cost models are likely to prove increasingly important in answering this question. Cost models deliver a number of benefits to a regulator willing to apply them, but they also ask for something in advance: information. Without information, the question cannot be answered. The authors introduce cost models and establish their applicability when different degrees of information are available to the regulator. They do no by running a cost model with different sets of actual data form Argentina's second largest city, and comparing results. Reliable, detailed information is generally scarce in developing countries. The authors establish the minimum information requirements for a regulator implementing a cost proxy model approach...

Private Infrastructure : Are the Trends in Low-income Countries Different?

Houskamp, Melissa; Tynan, Nicola
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Viewpoint; Publications & Research
ENGLISH
Relevância na Pesquisa
45.53%
This note, based on the World Bank's Private Participation in Infrastructure (PPI) project database, reviews trends in infrastructure projects with private participation in low-income countries. Four main conclusions arise. Surprisingly, the proportion of countries with at least one project - eighty one percent - is higher among low-income, than middle-income countries. As in middle-income countries, most investment has been in telecommunications, or energy projects. However, in low-income countries, well over half the projects are greenfield. And the scale of private participation in low-income countries, lags far behind that in middle-income countries.

Contribuições em codificação de imagens e vídeo = : Contributions in image and video coding; Contributions in image and video coding

Vanessa Testoni
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/11/2011 PT
Relevância na Pesquisa
45.43%
A comunidade de codificação de imagens e vídeo vem também trabalhando em inovações que vão além das tradicionais técnicas de codificação de imagens e vídeo. Este trabalho é um conjunto de contribuições a vários tópicos que têm recebido crescente interesse de pesquisadores na comunidade, nominalmente, codificação escalável, codificação de baixa complexidade para dispositivos móveis, codificação de vídeo de múltiplas vistas e codificação adaptativa em tempo real. A primeira contribuição estuda o desempenho de três transformadas 3-D rápidas por blocos em um codificador de vídeo de baixa complexidade. O codificador recebeu o nome de Fast Embedded Video Codec (FEVC). Novos métodos de implementação e ordens de varredura são propostos para as transformadas. Os coeficiente 3-D são codificados por planos de bits pelos codificadores de entropia, produzindo um fluxo de bits (bitstream) de saída totalmente embutida. Todas as implementações são feitas usando arquitetura com aritmética inteira de 16 bits. Somente adições e deslocamentos de bits são necessários, o que reduz a complexidade computacional. Mesmo com essas restrições, um bom desempenho em termos de taxa de bits versus distorção pôde ser obtido e os tempos de codificação são significativamente menores (em torno de 160 vezes) quando comparados ao padrão H.264/AVC. A segunda contribuição é a otimização de uma recente abordagem proposta para codificação de vídeo de múltiplas vistas em aplicações de video-conferência e outras aplicações do tipo "unicast" similares. O cenário alvo nessa abordagem é fornecer vídeo com percepção real em 3-D e ponto de vista livre a boas taxas de compressão. Para atingir tal objetivo...