Improvements in fibre optic communication and in VLSI for network switching components have led to the consideration of building digital switched networks capable of providing point to point communication in the gigabit per second range. Provision of bandwidths of this magnitude allows the consideration of a whole new range of telecommunications services, integrating video, voice, image and text. These multi-service networks have a range of requirements not met by traditional network architectures designed for digital telephony or computer applications. This dissertation describes the design, and an implementation, of the Multi-Service Network architecture and protocol family, which is aimed at supporting these services. Asynchronous transfer mode networks provide the basic support required for these integrated services, and the Multi-Service Network architecture is designed primarily for these types of networks. The aim of the Multi-Service protocol family is to provide a complete architecture which allows use of the full facilities of asynchronous transfer mode networks by multi-media applications. To maintain comparable performance with the underlying media, certain elements of the MSN protocol stack are designed with implementation in hardware in mind. The interconnection of heterogeneous networks, and networks belonging to different security and administrative domains, is considered vital, so the MSN architecture takes an internetworking approach.

No description available.

No description available.

No description available.

No description available.

No description available.

In this thesis admission stationary policies for small Symmetric Star telecommunication networks in which there are two types of calls requesting access are considered. Arrivals form independent Poisson streams on each route. We consider the routing to be fixed. The holding times of the calls are exponentially distributed periods of time. Rewards are earned for carrying calls and future returns are discounted at a fixed rate. The operation of the network is viewed as a Markov Decision Process and we solve the optimality equation for this network model numerically for a range of small examples by using the policy improvement algorithm of Dynamic Programming. The optimal policies we study involve acceptance or rejection of traffic requests in order to maximise the Total Expected Discounted Reward. Our Star networks are in some respect the simplest networks more complex than single links in isolation but even so only very small examples can be treated numerically. From those examples we find evidence that suggests that despite their complexity, optimal policies have some interesting properties. Admission Price policies are also investigated in this thesis. These policies are not optimal but they are believed to be asymptotically optimal for large networks. In this thesis we investigate if such policies are any good for small networks; we suggest that they are. A reduced state-space model is also considered in which a call on a 2-link route, once accepted, is split into two independent calls on the links involved. This greatly reduces the size of the state-space. We present properties of the optimal policies and the Admission Price policies and conclude that they are very good for the examples considered. Finally we look at Asymmetric Star networks with different number of circuits per link and different exponential holding times. Properties of the optimal policies as well as Admission Price policies are investigated for such networks.

No description available.

Includes bibliographical references / One of the political and economic responses to globalisation and the associated rise of multilateral trade agreements is the integration of national markets and their governance within regions. As developing economies have become increasingly integrated into the global economy, the harmonisation of policies and standardisation of regulations to create economies of scale and scope, has been one of the primary strategies to improve regional competitiveness. With the global economy underpinned by a dynamic communication infrastructure, African regional economic communities (RECs) have increasingly recognised the importance of Information and Communication Technology (ICT) in realising the vision of regional integration, and as a major determinant of national and regional competitiveness. Despite member states' acknowledgement of the need for regional connectivity, many initiatives across Africa aimed at supporting and establishing harmonised ICT policy frameworks have not had the intended outcomes. Strategies for developing seamless regional ICT infrastructures - necessary for the achievement of universal policy objectives of improved access to, and usage of, affordable broadband services now widely demonstrated to drive economic growth - have not been realised. Through a case study of regional policy-making in the Southern African Development Community (SADC), the thesis examines the political economy underlying regional processes and structures for the development and the implementation of ICT policy frameworks, as shaped by epistemic communities. A conceptual framework is constructed as a lens through which to assess the role of capacity building as a tool in foreign affairs in the institutional arrangements within SADC countries and ICT policy outcomes in the region. This reveals the wider political, economic and more specific policy and regulatory constraints hampering the development of the information society from a developing region perspective. Applying a hybrid methodology, empirical information was gathered through quantitative secondary data but using qualitative methods to gather the primary evidence for the case. This evidence from multiple sources is examined through a broad political economy framework to contextualise the research problem and develop a rich narrative of regional integration efforts in the area of information communication technologies in the Southern African Development Community (SADC). Following rigorous and extensive gathering of information from face to face interviews following an exhaustive document analysis, detailed coding of the data and triangulation of findings enable d an analysis of how institutional arrangement s in the region -despite the accepted rationale and logic of market integration -have largely failed to achieve the intended IV ICT policy objectives stated in SADC protocols and declarations despite considerable advances in the formal harmonisation of aspects of ICT policy and regulation.

O jitter de fase é um fenômeno inerente nos sistemas elétricos. O crescente interesse pelo jitter deve-se à degradação que causa em sistemas de transmissão de alta velocidade. Seus efeitos fazem-se sentir ao afetar o processo de recuperação de dados, causando aumento na taxa de erros por bit. Neste trabalho, o jitter é modelado como uma perturbação periódica e seu efeito na operação de PLLs é analisado. Deduzimos uma fórmula para o cálculo da amplitude do jitter envolvendo somente os parâmetros do PLL e do jitter e identificamos as regiões do espaço de parâmetros com os comportamentos dinâmicos do PLL. / Phase jitter or timing jitter is an inherent phenomenum on electrical systems. Jitter growing interest is due to degradation it causes in high-speed transmission systems. It affects the data recovering process and it causes an increase in the bit error rate. In this work, jitter is modelled as a periodic perturbation and its effects in the operation of a PLL are analysed. We deduce a formula that measures jitter amplitude by PLL and jitter parameters and we identify the regions of parameter space according to the system dynamical behaviour.