Multichannel optical access networks : design and resource management

At present there is a strong worldwide push towards bringing fiber closer to individual homes and businesses. The next evolutionary step is the cost-effective all-optical integration of fiber-based access and metro networks. STARGATE [1] is an all-optical access-metro architecture which does not rely on costly active devices, e.g., Optical Cross-Connects (OXCs) or Fixed Wavelength Converters (FWCs), and allow low-cost PON technologies to follow low-cost Ethernet technologies from EPON access into metro networks, resulting in significantly reduced cost and complexity. It makes use of an overlay island of transparency with optical bypassing capabilities. In this thesis we first propose Optical Network Unit (ONU) architectures, and discuss several technical challenges, which allow STARGATE EPONs (SG-EPONs) to evolve in a pay-as-you-grow manner while providing backward compatibility with legacy infrastructure and protecting previous investment. Second, and considering all the hardware constraints, we present the corresponding dynamic bandwidth allocation algorithm for effective resource management in these networks and investigate their performances (delay, throughput) through simulation experiments. We further investigate the problem of transmission grant scheduling in multichannel optical access networks using a scheduling theoretic approach. We show that the problem can be modeled as an Open Shop and we formulate the joint scheduling and wavelength assignment problem as a Mixed Integer Linear Program (MJLP) whose objective is to reduce the length of a scheduling period. Since the problem is known to be NP-hard, we introduce a Tabu Search based heuristic for solving the joint problem. Different other heuristics are also considered and their performances are compared with those of Tabu and MILP. Results indicate that by appropriately scheduling transmission grants and assigning wavelengths, substantial and consistent improvements may be obtained in the network performance. For example, Tabu shows a reduction of up to 29% in the schedule length with substantial reduction in channel idle gaps yielding to both higher channel utilization and lower queuing delays. Additionally, when the number of channels in the network is not small, the benefits of performing appropriate wavelength assignment, together with transmission scheduling, are observed and discussed. We further perform a packet-level simulation on the considered network to study the benefits of efficient grant scheduling; significant improvements are shown both in terms of system utilization and packet queuing delays

Optimization Methods for Optical Long-Haul and Access Networks

Optical communications based on fiber optics and the associated technologies have seen remarkable progress over the past two decades. Widespread deployment of optical fiber has been witnessed in backbone and metro networks as well as access segments connecting to customer premises and homes. Designing and developing a reliable, robust and efficient end-to-end optical communication system have thus emerged as topics of utmost importance both to researchers and network operators. To fulfill these requirements, various problems have surfaced and received attention, such as network planning, capacity placement, traffic grooming, traffic scheduling, and bandwidth allocation. The optimal network design aims at addressing (one or more of) these problems based on some optimization objectives. In this thesis, we consider two of the most important problems in optical networks; namely the survivability in optical long-haul networks and the problem of bandwidth allocation and scheduling in optical access networks. For the former, we present efficient and accurate models for availability-aware design and service provisioning in p-cycle based survivable networks. We also derive optimization models for survivable network design based on p-trail, a more general protection structure, and compare its performance with p-cycles. Indeed, major cost savings can be obtained when the optical access and long-haul subnetworks become closer to each other by means of consolidation of access and metro networks. As this distance between long-haul and access networks reduces, and the need and expectations from passive optical access networks (PONs) soar, it becomes crucial to efficiently manage bandwidth in the access while providing the desired level of service availability in the long-haul backbone. We therefore address in this thesis the problem of bandwidth management and scheduling in passive optical networks; we design efficient joint and non-joint scheduling and bandwidth allocation methods for multichannel PON as well as next generation 10Gbps Ethernet PON (10G-EPON) while addressing the problem of coexistence between 10G-EPONs and multichannel PONs

Design and Analysis of Green Mission-Critical Fiber-Wireless Broadband Access Networks

In recent years, the ever-increasing environmental friendliness concern has made energy efficiency in telecom networks as an important theme in their operations. Meanwhile, mission-critical (MC) services and systems (such as healthcare, police, and firefighting) have been acquiring special attention from telecom designers and operators. The currently deployed MC network technologies are indigent in terms of bandwidth capacity, and thus they are not able to support the emerging MC multimedia applications. Therefore in this thesis, we first explore the possibility of provisioning the MC services over the integration of fiber-wireless (FiWi) technologies, which has been considered as a promising candidate for the deployment of high-speed and mobile broadband access networks. We then investigate the energy efficiency problem in the FiWi integration, which consists of WiMAX in the wireless plane, and of Ethernet Passive Optical Network (EPON) - the most popular variant of the next-generation PON (NG-PON) technology, in the optical plane. In WiMAX, the energy saving protocol has been extensively investigated and standardized. Conversely, it has been recently studied in NG-PON, which currently consumes the least power among all the high-speed access networks. However, NG-PON has notably matured in the past few years and is envisioned to massively evolve in the near future. This trend will increase the power requirements of NG-PON and make it no longer coveted. Therefore we address the energy efficiency problem in NG-PON. For each of our contributions, we conduct extensive simulations to demonstrate the effectiveness and advantages of the proposed solutions

Methodology for designing PON networks

Cílem této práce je analyzovat současný stav přístupových optických sítí,a hlouběji prozkoumat PON metodiku a návrh sítě. Navrhnul jsem síť založenou na konceptu FTTH pro 90 rodinných domů ovládané z centrální stanice vzdálené 20 km. Zabýval jsem se problémy při návrhu FTTH, konkrétně pasivní optickou sítí. Dále jsem se zabýval ATM-PON a Ethernet PON (EPON), které jsou založeny na společné síťové architektuře, PON, ale používají jiné přenosové technologie na podporu integrovaných služeb a jiné protokoly. Po zadání (optimálního) síťového řešení, které se hodí pro nabídku Triple-Play služeb. Dále budu popisovat, jak fungují síťová propojení a také budou popsány metody měření a testování navržené sítě "po aktivaci a nastavení sítě" a "před aktivací síťových služeb ". Při měření jsem také používal OTDR a prakticky ověřil charakteristiku linky. V práci je také naznačeno monitorování optické sítě.The purpose of this thesis is to analyze the present condition of Access network, in depth research of PON Methodology and network design. I shall design a Network project based on FTTH for building a network of 90 private houses controlled by a central control point from 20km distance. Where I shall address these issues and expedite the introduction of FTTH, and I will reason behind (PON) network-based solution, and so on ATM-PON and Ethernet PON (EPON), which are based on common network architecture, PON, but adopt different transfer technologies to support integrated services and multiple protocols. After providing the (optimal) network solution that fits to fulfill Triple-Play requirements, I will describe how the network interconnects and how it functions and work, later on I shall go into describing the measuring methods and testing for the defined network “after activating and setting the network” and “before activating the network service” where I will also use the OTDR and practically apply a link characterization test. And suggest the monitoring of the design model of the project.

Redes ópticas passivas de próxima geração (NG-PON)

Mestrado em Engenharia Electrónica e TelecomunicaçõesAs redes ópticas passivas (PONs) prometem satisfazer os requisitos dos utilizadores e provedores de serviços de forma a obter débitos mais elevados, quando comparados com as tecnologias baseadas em cobre. Com este trabalho pretende-se estudar e apresentar as tecnologias PON correntes actualmente, as suas características principais e alguma interpretação de como estas conseguem satisfazer os requisitos impostos. Vários standards para PON têm vindo a ser desenvolvidos ao longo dos anos e, considerando que a necessidade de melhores características de serviço é contínua, surgiram as redes ópticas passivas de próxima geração. As NG-PONs prometem satisfazer as exigências dos novos serviços, garantindo melhor qualidade de serviço global que os seus antecessores. Neste trabalho as recomendações do ITU-T e do IEEE são estudadas e apresentadas em detalhe e, como corolário, são comparadas por forma a identificar as suas diferenças e semelhanças. Com base nos conhecimentos obtidos, e com o intuito de validar por simulação alguns dos limites impostos pelas normas são feitas várias simulações de uma rede PON, seguindo a norma 10G-EPON. São variados parâmetros como distância da fibra, número máximo de utilizadores e perdas máximas por inserção de forma a poder avaliar o seu efeito e enquadrar com a norma obtida.Passive Optical networks (PONs) promise to overcome the requirements of users and service providers to achieve higher data rates than conventional cooper Technologies. This work study and present the actual PON technologies, their main features and how they can successfully fulfill the imposed requirements. Several PON recommendations have appeared all over the years and due to ever increasing demand of improved services, PON networks evolved to Next Generation Passive Optical Networks. NG-PONs come to respond to the new quality and demanding services, ensuring better global performance than their antecessors. The ITU-T and IEEE recommendations are studied and presented in detail, and by corollary are compared in order to easily comprehend the differences and similarities between them. Based on the knowledge obtained and with the aim of validate by simulation some of the boundaries imposed by the recommendations, several simulations of a PON network are performed, following the 10G-EPON standard. Parameters like, fiber distance, number of users and maximum insertion loss are changed to evaluate their impact in the PON performance and to frame them in the recommendation