Cross-layer modeling and optimization of next-generation internet networks

Scaling traditional telecommunication networks so that they are able to cope with the volume of future traffic demands and the stringent European Commission (EC) regulations on emissions would entail unaffordable investments. For this very reason, the design of an innovative ultra-high bandwidth power-efficient network architecture is nowadays a bold topic within the research community. So far, the independent evolution of network layers has resulted in isolated, and hence, far-from-optimal contributions, which have eventually led to the issues today's networks are facing such as inefficient energy strategy, limited network scalability and flexibility, reduced network manageability and increased overall network and customer services costs. Consequently, there is currently large consensus among network operators and the research community that cross-layer interaction and coordination is fundamental for the proper architectural design of next-generation Internet networks. This thesis actively contributes to the this goal by addressing the modeling, optimization and performance analysis of a set of potential technologies to be deployed in future cross-layer network architectures. By applying a transversal design approach (i.e., joint consideration of several network layers), we aim for achieving the maximization of the integration of the different network layers involved in each specific problem. To this end, Part I provides a comprehensive evaluation of optical transport networks (OTNs) based on layer 2 (L2) sub-wavelength switching (SWS) technologies, also taking into consideration the impact of physical layer impairments (PLIs) (L0 phenomena). Indeed, the recent and relevant advances in optical technologies have dramatically increased the impact that PLIs have on the optical signal quality, particularly in the context of SWS networks. Then, in Part II of the thesis, we present a set of case studies where it is shown that the application of operations research (OR) methodologies in the desing/planning stage of future cross-layer Internet network architectures leads to the successful joint optimization of key network performance indicators (KPIs) such as cost (i.e., CAPEX/OPEX), resources usage and energy consumption. OR can definitely play an important role by allowing network designers/architects to obtain good near-optimal solutions to real-sized problems within practical running times

Regenerator placement and fault management in multi-wavelength optical networks.

Shen, Dong.Thesis (M.Phil.)--Chinese University of Hong Kong, 2011.Includes bibliographical references (p. 98-106).Abstracts in English and Chinese.Abstract --- p.i摘要 --- p.ivAcknowledgements --- p.vTable of Contents --- p.viChapter Chapter 1 --- Background --- p.1Chapter 1.1 --- Translucent Optical Networks --- p.1Chapter 1.1.1 --- The Way Towards Translucent --- p.1Chapter 1.1.2 --- Translucent Optical Network Architecture Design and Planning --- p.3Chapter 1.1.3 --- Other Research Topics in Translucent Optical Networks --- p.6Chapter 1.2 --- Fault Monitoring in All-Optical Networks --- p.12Chapter 1.2.1 --- Fault Monitoring in Network Layer's Perspective --- p.12Chapter 1.2.2 --- Passive Optical Monitoring --- p.14Chapter 1.2.3 --- Proactive Optical Monitoring --- p.16Chapter 1.3 --- Contributions --- p.17Chapter 1.3.1 --- Translucent Optical Network Planning with Heterogeneous Modulation Formats --- p.17Chapter 1.3.2 --- Multiplexing Optimization in Translucent Optical Networks --- p.19Chapter 1.3.3 --- An Efficient Regenerator Placement and Wavelength Assignment Scheme in Translucent Optical Networks --- p.20Chapter 1.3.4 --- Adaptive Fault Monitoring in All-Optical Networks Utilizing Real-Time Data Traffic --- p.20Chapter 1.4 --- Organization of Thesis --- p.22Chapter Chapter 2 --- Regenerator Placement and Resource Allocation Optimization in Translucent Optical Networks --- p.23Chapter 2.1 --- Introduction --- p.23Chapter 2.2 --- Translucent Optical Network Planning with Heterogeneous Modulation Formats --- p.25Chapter 2.2.1 --- Motivation and Problem Statements --- p.25Chapter 2.2.2 --- A Two-Step Planning Algorithm Using Two Modulation Formats to Realize Any-to-Any Topology Connectivity --- p.28Chapter 2.2.3 --- Illustrative Examples --- p.30Chapter 2.2.3 --- ILP Formulation of Minimizing Translucent Optical Network Cost with Two Modulation Formats under Static Traffic Demands --- p.34Chapter 2.2.4 --- Illustrative Numeric Examples --- p.42Chapter 2.3 --- Resource Allocation Optimization in Translucent Optical Networks --- p.45Chapter 2.3.1 --- Multiplexing Optimization with Auxiliary Graph --- p.45Chapter 2.3.2 --- Simulation Study of Proposed Algorithm --- p.51Chapter 2.3.3 --- An Efficient Regenerator Placement and Wavelength Assignment Solution --- p.55Chapter 2.3.4 --- Simulation Study of Proposed Algorithm --- p.60Chapter 2.4 --- Summary --- p.64Chapter Chapter 3 --- Adaptive Fault Monitoring in All-Optical Networks Utilizing Real-Time Data Traffic --- p.65Chapter 3.1 --- Introduction --- p.65Chapter 3.2 --- Adaptive Fault Monitoring --- p.68Chapter 3.2.1 --- System Framework --- p.68Chapter 3.2.2 --- Phase 1: Passive Monitoring --- p.70Chapter 3.2.3 --- Phase 2: Proactive Probing --- p.71Chapter 3.2.4 --- Control Plane Design and Analysis --- p.80Chapter 3.2.5 --- Physical Layer Implementation and Suggestions --- p.83Chapter 3.3 --- Placement of Label Monitors --- p.83Chapter 3.3.1 --- ILP Formulation --- p.84Chapter 3.3.2 --- Simulation Studies --- p.86Chapter 3.3.3 --- Discussion of Topology Evolution Adaptiveness --- p.93Chapter 3.4 --- Summary --- p.95Chapter Chapter 4 --- Conclusions and Future Work --- p.95Chapter 4.1 --- Conclusions --- p.96Chapter 4.2 --- Future Work --- p.97Bibliography --- p.98Publications during M.Phil Study --- p.10

An integrated view on monitoring and compensation for dynamic optical networks: from management to physical layer

A vertical perspective, ranging from management and routing to physical layer options, concerning dynamic network monitoring and compensation of impairments (M&C), is given. Feasibility, reliability, and performance improvements on reconfigurable transparent networks are expected to arise from the consolidated assessment of network management and control specifications, as a more accurate evaluation of available M&C techniques. In the network layer, physical parameters aware algorithms are foreseen to pursue reliable network performance. In the physical layer, some new M&C methods were developed and rating of the state-of-the-art reported in literature is given. Optical monitoring implementation and viability is discussed.Publicad

Energy Efficient Core Networks with Clouds

The popularity of cloud based applications stemming from the high volume of connected mobile devices has led to a huge increase in Internet traffic. In order to enable easy access to cloud applications, infrastructure providers have invested in geographically distributed databases and servers. However, intelligent and energy efficient high capacity transport networks with near ubiquitous connectivity are needed to adequately and sustainably serve these requirements. In this thesis, network virtualisation has been identified as a potential networking paradigm that can contribute to network agility and energy efficiency improvements in core networks with clouds. The work first introduces a new virtual network embedding core network architecture with clouds and a compute and bandwidth resource provisioning mechanism aimed at reducing power consumption in core networks and data centres. Further, quality of service measures in compute and bandwidth resource provisioning such as delay and customer location have been investigated and their impact on energy efficiency established. Data centre location optimisation for energy efficiency in virtual network embedding infrastructure has been investigated by developing a MILP model that selects optimal data centre locations in the core network. The work also introduces an optical OFDM based physical layer in virtual network embedding to optimise power consumption and optical spectrum utilization. In addition, virtual network embedding schemes aimed at profit maximization for cloud infrastructure providers as well greenhouse gas emission reduction in cloud infrastructure networks have been investigated. GreenTouch, a consortium of industrial and academic experts on energy efficiency in ICTs, has adopted the work in this thesis as one of the measures of improving energy efficiency in core networks

Amplificadores de fibra em redes óticas transparentes e dinâmicas

Doutoramento em Engenharia EletrotécnicaIn this thesis a study of optical fiber amplifiers in the context of transparent and dynamic optical networks is performed. We propose and validate a simplified model to estimate the gain profile and amplified spontaneous emission (ASE) noise of broadband counterpumped Raman fiber amplifiers (RFAs). The proposed model requires very low computational resources and it is suitable to be used in network planning tools. Based on the proposed model, we also present an algorithm to design flat gain counter-pumped RFAs for the extended C-band with low computational requirements. We experimentally verify that the pump-reflecting RFA presents a higher transient response due to channels add/drop, when compared to the conventional counter-pumped RFA. This makes this amplifier configuration unsuitable for transparent and dynamic optical networks. To mitigate the transient response due to channel add/drop, a pumpcontrolled gain-locked system based on the monitorization of the reflected pump power is proposed and validated numerically and experimentally. Following this approach, an efficient low-cost RFA suitable for dynamic optical networks is proposed. The dependence of the dynamical response of erbium-doped fiber amplifiers (EDFAs) on the pump wavelength, pump power, and temperature due to spectral hole burning (SHB) and site dependent pumping (SDP) is experimentally investigated. A dependence of the dynamic response on the pump wavelength, for amplifiers pumped around 1480 nm, is shown. In order to explain this dependence, the impact of SDP on the performance of EDFAs pumped at wavelengths around 1480 nm is investigated, both experimentally and numerically. As a result, an improved model incorporating the SDP effect for twolevel EDFAs is derived and experimentally validated.Nesta tese é feito um estudo sobre amplificadores de fibra ótica no contexto de redes óticas transparentes e dinâmicas. Propomos e validamos um modelo simplificado para estimar o perfil do ganho e do ruído de emissão espontânea amplificada (ASE), para amplificadores de Raman (RFAs) contra propagantes. O modelo proposto requer baixos recursos computacionais e é adequado para ser usado em ferramentas de planeamento da rede. Com base no modelo proposto, apresentamos também um algoritmo com requisitos computacionais baixos para desenhar RFAs contra propagantes com ganho constante para a banda C estendida. Verificamos experimentalmente que um RFA contra propagante com reflexo da potência da bomba devido à adição/remoção de canais apresenta uma resposta transiente mais elevada, quando comparado com um RFA contra propagante convencional. Isto torna esta configuração inadequada para redes óticas transparentes e dinâmicas. Para mitigar a resposta transitória devido à adição/remoção de canais, um sistema de controlo do ganho baseado na monitorização da potência da bomba refletida é proposto e validado numérica e experimentalmente. Seguindo esta abordagem, um RFA contra propagante eficiente e de baixo custo adequado para redes óticas dinâmicas é proposto. A dependência da resposta dinâmica dos amplificadores de fibra dopada com érbio (EDFAs) em função do comprimento de onda da bomba, da potência da bomba e da temperatura devido ao spectral hole burning (SHB) e site dependent pumping (SDP) é investigada experimentalmente. Nos resultados obtidos é mostrada a dependência da resposta dinâmica em função do comprimento de onda da bomba, para amplificadores bombeados em torno de 1480 nm. Para explicar esta dependência, o impacto do SDP no desempenho de EDFAs bombeados em comprimentos de onda em torno de 1480 nm é investigado, tanto experimental como numericamente. Como resultado, um modelo mais completo, incorporando o efeito SDP para EDFAs de dois níveis é derivado e validado experimentalmente

ReSCon '12, Research Student Conference: Book of Abstracts

The fifth SED Research Student Conference (ReSCon2012) was hosted over three days, 18-20 June 2012, in the Hamilton Centre at Brunel University. The conference consisted of 130 oral and 70 poster presentations, based on the high quality and diverse research being conducted within the School of Engineering and Design by postgraduate research students. The conference is held annually, and ReSCon plays a key role in contributing to research and innovations within the School