Some aspects of traffic control and performance evaluation of ATM networks

The emerging high-speed Asynchronous Transfer Mode (ATM) networks are expected to integrate through statistical multiplexing large numbers of traffic sources having a broad range of statistical characteristics and different Quality of Service (QOS) requirements. To achieve high utilisation of network resources while maintaining the QOS, efficient traffic management strategies have to be developed. This thesis considers the problem of traffic control for ATM networks. The thesis studies the application of neural networks to various ATM traffic control issues such as feedback congestion control, traffic characterization, bandwidth estimation, and Call Admission Control (CAC). A novel adaptive congestion control approach based on a neural network that uses reinforcement learning is developed. It is shown that the neural controller is very effective in providing general QOS control. A Finite Impulse Response (FIR) neural network is proposed to adaptively predict the traffic arrival process by learning the relationship between the past and future traffic variations. On the basis of this prediction, a feedback flow control scheme at input access nodes of the network is presented. Simulation results demonstrate significant performance improvement over conventional control mechanisms. In addition, an accurate yet computationally efficient approach to effective bandwidth estimation for multiplexed connections is investigated. In this method, a feed forward neural network is employed to model the nonlinear relationship between the effective bandwidth and the traffic situations and a QOS measure. Applications of this approach to admission control, bandwidth allocation and dynamic routing are also discussed. A detailed investigation has indicated that CAC schemes based on effective bandwidth approximation can be very conservative and prevent optimal use of network resources. A modified effective bandwidth CAC approach is therefore proposed to overcome the drawback of conventional methods. Considering statistical multiplexing between traffic sources, we directly calculate the effective bandwidth of the aggregate traffic which is modelled by a two-state Markov modulated Poisson process via matching four important statistics. We use the theory of large deviations to provide a unified description of effective bandwidths for various traffic sources and the associated ATM multiplexer queueing performance approximations, illustrating their strengths and limitations. In addition, a more accurate estimation method for ATM QOS parameters based on the Bahadur-Rao theorem is proposed, which is a refinement of the original effective bandwidth approximation and can lead to higher link utilisation

BMSN and SpiderNet as large scale ATM switch interconnection architectures.

by Kin-Yu Cheung.Thesis (M.Phil.)--Chinese University of Hong Kong, 1997.Includes bibliographical references (leaves 64-[68]).Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Multistage Interconnection Architectures --- p.2Chapter 1.2 --- Interconnection Topologies --- p.4Chapter 1.3 --- Design of Switch Module-An Example of Multichannel Switch --- p.7Chapter 1.4 --- Organization --- p.8Chapter 1.5 --- Publication --- p.9Chapter 2 --- BMSN and SpiderNet: Two Large Scale ATM Switches --- p.13Chapter 2.1 --- Introduction --- p.13Chapter 2.2 --- Architecture --- p.14Chapter 2.2.1 --- Topology --- p.14Chapter 2.2.2 --- Switch Modules --- p.15Chapter 2.3 --- Routing --- p.17Chapter 2.3.1 --- VP/VC Routing --- p.18Chapter 2.3.2 --- VP/VC Routing Control --- p.22Chapter 2.3.3 --- Cell Routing --- p.23Chapter 2.3.4 --- Alternate Path Routing for Fault Tolerance --- p.24Chapter 2.4 --- SpiderNet --- p.25Chapter 2.5 --- Performance and Discussion --- p.26Chapter 2.5.1 --- BMSN vs SpiderNet --- p.26Chapter 2.5.2 --- Network Capacity --- p.29Chapter 2.6 --- Concluding Remarks --- p.30Chapter 3 --- Multichannel ATM Switching --- p.39Chapter 3.1 --- Introduction --- p.39Chapter 3.2 --- Switch Design --- p.40Chapter 3.3 --- Channel Allocation Algorithms --- p.41Chapter 3.3.1 --- VC-Based String Round Robin (VCB-SRR) Algorithm --- p.41Chapter 3.3.2 --- Implementation of the VCB-SRR Algorithm --- p.43Chapter 3.3.3 --- Channel Group Based Round Robin (CGB-RR) Algorithm --- p.50Chapter 3.3.4 --- Implementation of the CGB-RR Algorithm --- p.51Chapter 3.4 --- Performance and Discussion --- p.53Chapter 3.5 --- Concluding Remarks --- p.57Chapter 4 --- Conclusion --- p.62Bibliography --- p.6

Proceedings of the Fifth International Mobile Satellite Conference 1997

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments

Designing a large scale switch interconnection architecture and a study of ATM scheduling algorithms.

by Yee Ka Chi.Thesis (M.Phil.)--Chinese University of Hong Kong, 1997.Includes bibliographical references (leaves 101-[106]).Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Background --- p.1Chapter 1.1.1 --- Large Scale Switch Interconnections --- p.2Chapter 1.1.2 --- Multichannel Switching and Resequencing --- p.6Chapter 1.1.3 --- Scheduling --- p.7Chapter 2 --- Hierarchical Banyan Switch Interconnection --- p.12Chapter 2.1 --- Introduction --- p.12Chapter 2.2 --- Switch Architecture --- p.13Chapter 2.3 --- Switch Operation --- p.19Chapter 2.3.1 --- Call Setup --- p.19Chapter 2.3.2 --- Cell Routing --- p.21Chapter 2.3.3 --- Fault Tolerance --- p.27Chapter 2.4 --- Call Blocking Analysis --- p.28Chapter 2.4.1 --- Dilated Banyan --- p.29Chapter 2.4.2 --- Dilated Benes Network --- p.30Chapter 2.4.3 --- HBSI --- p.30Chapter 2.5 --- Results and Discussions --- p.31Chapter 2.6 --- Summary --- p.37Chapter 3 --- Multichannel Switching and Resequencing --- p.40Chapter 3.1 --- Introduction --- p.40Chapter 3.2 --- Channel Assignment --- p.41Chapter 3.2.1 --- VC-Based Channel Allocation Mechanism --- p.41Chapter 3.2.2 --- Port-Based Channel Allocation Mechanism --- p.45Chapter 3.2.3 --- Trunk-Based Channel Allocation Mechanism --- p.46Chapter 3.3 --- Resequencer --- p.50Chapter 3.3.1 --- Resequencing Algorithm --- p.50Chapter 3.4 --- Results and Discussion --- p.55Chapter 3.5 --- Summary --- p.60Chapter 4 --- Scheduling --- p.62Chapter 4.1 --- Introduction --- p.62Chapter 4.2 --- Virtual Clock Scheduling (VCS) --- p.62Chapter 4.3 --- Gated Virtual Clock Scheduling (GVCS) --- p.70Chapter 4.4 --- Time-Priority Model --- p.75Chapter 4.5 --- Programmable Rate-based Scheduler (PRS) --- p.80Chapter 4.6 --- Integration with Resequencer --- p.83Chapter 4.7 --- Results and Discussions --- p.86Chapter 4.8 --- Summary --- p.96Chapter 5 --- Conclusion --- p.99Bibliography --- p.10

Dimensionamento de redes ATM multi-serviço : modelos de programação linear inteira

Engenharia ElectrotécnicaEsta tese aborda o problema do dimensionamento de redes ATM (Asynchronous Transfer Mode) num cenário multi-serviço de suporte a serviços com diferentes características de tráfego: serviços conversacionais, serviços de consulta e serviços ponto-multiponto. O problema estudado considera a perspectiva de um operador de telecomunicações que tem como objectivo a determinação da rede física com o menor custo de operação e manutenção possível e que seja capaz de suportar o tráfego esperado para os diferentes serviços com a qualidade de serviço necessária. Os problemas de dimensionamento abordados consideram serviços comutados em que cada serviço é suportado por uma rede lógica constituída por VPCs (Virtual Path Connections) do tipo DBR (Deterministic Bit Rate) e o encaminhamento é fixo (uni-horário e multi-horário). O primeiro problema endereçado é o dimensionamento de redes ATM em que as redes lógicas de suporte a todos os tipos de serviços são constituídas exclusivamente por VPCs extremo-a-extremo. Esta arquitectura tem como principal vantagem a simplificação dos mecanismos de CAC (Call Admission Control) da rede. São propostos modelos de Programação Inteira para este problema. Os modelos desenvolvidos extendem modelos previamente conhecidos para serviços conversacionais de modo a poder ser considerado tráfego assimétrico (característico dos serviços de consulta e serviços pontomultiponto) e a modelização de VPCs em que um dos extremos não é conhecido à partida (característico dos serviços de consulta quando existem múltiplos servidores na rede). É proposto um algoritmo heurístico baseado na técnica da Relaxação Lagrangeana com Optimização por Sub-Gradiente para a resolução dos modelos desenvolvidos em redes de grande dimensão. No entanto, uma arquitectura baseada em VPCs extremo-a-extremo conduz a uma utilização pouco eficiente dos recursos da rede e, para redes de maiores dimensões, torna-se impraticável pelo elevado número de VPCs que exige. Como alternativa, são propostas duas arquitecturas diferentes. Para serviços conversacionais, é proposta uma arquitectura hierarquizada a 2 níveis para as redes lógicas de suporte. Esta arquitectura permite reduzir significativamente o número total de VPCs que é necessário configurar na rede sem contudo permitir que o número máximo de VPCs atravessados por cada ligação seja maior que três (um factor determinante para serviços comutados em que o tempo de estabelecimento de chamada é um parâmetro de qualidade de serviço a ter em consideração). Para serviços ponto-multiponto, é proposta uma arquitectura em árvore para as redes lógicas de suporte. São propostos modelos de Programação Inteira e Programação Inteira Mista para os problemas de dimensionamento da rede com as redes lógicas segundo as arquitecturas propostas. A resolução dos modelos propostos através de um algoritmo de branch-and-bound permite demonstrar que as arquitecturas alternativas propostas conduzem a ganhos significativos nos custos das redes obtidas quando comparados com os custos que se obtêm com redes lógicas baseadas em VPCs extremo-a-extremo