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

A low-energy rate-adaptive bit-interleaved passive optical network

Energy consumption of customer premises equipment (CPE) has become a serious issue in the new generations of time-division multiplexing passive optical networks, which operate at 10 Gb/s or higher. It is becoming a major factor in global network energy consumption, and it poses problems during emergencies when CPE is battery-operated. In this paper, a low-energy passive optical network (PON) that uses a novel bit-interleaving downstream protocol is proposed. The details about the network architecture, protocol, and the key enabling implementation aspects, including dynamic traffic interleaving, rate-adaptive descrambling of decimated traffic, and the design and implementation of a downsampling clock and data recovery circuit, are described. The proposed concept is shown to reduce the energy consumption for protocol processing by a factor of 30. A detailed analysis of the energy consumption in the CPE shows that the interleaving protocol reduces the total energy consumption of the CPE significantly in comparison to the standard 10 Gb/s PON CPE. Experimental results obtained from measurements on the implemented CPE prototype confirm that the CPE consumes significantly less energy than the standard 10 Gb/s PON CPE

Avaliação do consumo energético de uma rede de acesso

Trabalho final de mestrado para obtenção do grau de Mestre em Engenharia de Eletrónica e TelecomunicaçõesO tráfego de internet está a crescer de forma exponencial e assim irá continuar nos próximos anos. Este crescimento é guiado por um conjunto de fatores, entre os quais está o aumento de utilizadores e o aparecimento de novos serviços e aplicações com elevados requisitos de largura de banda. A medida que o tráfego cresce, a quantidade, a capacidade, o custo e consumo energético dos equipamentos necessários para distribuir o tráfego também cresce, como resultado, a contribuição do setor das telecomunicações para consumo de energia a nível mundial aumentou consideravelmente na última década. Sendo o consumo energético um elemento importante para o OPEX (Operational Expenditure), consequentemente, em adição aos habituais cálculos de capacidade, throughput e QoS(Quality of Service), que impactuam o CAPEX (Capital Expenditure), é importante tê-lo em conta no momento de decidir que tecnologia adotar, no entanto o consumo energético ainda é geralmente ignorado no debate sobre a implementação da rede. Neste trabalho, dois modelos de avaliação do consumo energético de uma rede de acesso, que se focam no desempenho energético dos dispositivos ativos na rede de acesso,são analisados e aplicados a um conjunto de tecnologias de rede óticas atuais e futuras selecionadas para o estudo. Inicialmente os modelos são aplicados a uma rede com rácio de divisão de 1:64 e capaz de servir 16384 utilizadores. De seguida, os modelos são novamente aplicados, agora com os rácios de divisão ajustados de forma a se obter o máximo rendimento de cada tecnologia ótica. Desse modo, o consumo de energia das diversas tecnologias deredes de acesso de próxima geração é avaliado, bem como em que situações podem ser extraídos o máximo potencial das mesmas. Os cálculos são realizados através da ferramenta Matlab, num estado estático globalda rede. Depois de avaliar os resultados, são tiradas conclusões sobre as diferenças no consumo de energia. Destaca-se, portanto, o efeito sobre o consumo de energia da tecnologia e o desempenho a longo prazo bem como as diferenças entre os modelos.Abstract: The Internet traffic is growing exponentially and so will continue in the coming years. This growth is guided by a number of factors, among which are an increase in users and the appearance of new services and applications with high bandwidth requirements. As traffic grows, the quantity, capacity, cost and power consumption of the equipment needed to deliver traffic also grows as a result, the contribution of the telecommunications sector to energy consumption worldwide has increased considerably in the last decade. As the energy consumption an important element in the OPEX, consequently, in addition to the usual calculations of capacity, throughput and QoS, which influence CAPEX, it is important to take it into account when deciding to adopt technology, but energy consumption is still generally ignored in the debate on the implementation of the network. In this study, two models of the energy consumption of an access network, which focus the energy performance of the active devices in access network are analyzed and applied to a current set of optical network technologies and future selected for the study. Initially the models are applied to a network with a 1:64 split ratio and capable of serving 16384 users. Then, the templates are reapplied, now with the division ratios adjusted to obtain the maximum yield of each optical technology. Thus, the power consumption of the various technologies of the next generation access networks is evaluated, and in which situations can be extracted from the full potential thereof. Calculations are performed by Matlab, in a global static state of the network. After evaluating the results, conclusions are drawn about the differences in energy consumption. It is noteworthy, therefore, the effect on the power consumption of the technology and the longterm performance as well as differences between models.N/

WDM/TDM PON bidirectional networks single-fiber/wavelength RSOA-based ONUs layer 1/2 optimization

This Thesis proposes the design and the optimization of a hybrid WDM/TDM PON at the L1 (PHY) and L2 (MAC) layers, in terms of minimum deployment cost and enhanced performance for Greenfield NGPON. The particular case of RSOA-based ONUs and ODN using a single-fibre/single-wavelength is deeply analysed. In this WDM/TDM PON relevant parameters are optimized. Special attention has been given at the main noise impairment in this type of networks: the Rayleigh Backscattering effect, which cannot be prevented. To understand its behaviour and mitigate its effects, a novel mathematical model for the Rayleigh Backscattering in burst mode transmission is presented for the first time, and it has been used to optimize the WDM/TDM RSOA based PON. Also, a cost-effective, simple design SCM WDM/TDM PON with rSOA-based ONU, was optimized and implemented. This prototype was successfully tested showing high performance, robustness, versatility and reliability. So, the system is able to give coverage up to 1280 users at 2.5 Gb/s / 1.25 Gb/s downstream/upstream, over 20 Km, and being compatible with the GPON ITU-T recommendation. This precedent has enabled the SARDANA network to extend the design, architecture and capabilities of a WDM/TDM PON for a long reach metro-access network (100 km). A proposal for an agile Transmission Convergence sub-layer is presented as another relevant contribution of this work. It is based on the optimization of the standards GPON and XG-PON (for compatibility), but applied to a long reach metro-access TDM/WDM PON rSOA-based network with higher client count. Finally, a proposal of physical implementation for the SARDANA layer 2 and possible configurations for SARDANA internetworking, with the metro network and core transport network, are presented

Resource management research in ethernet passive optical networks

The last decades, we have witnessed different phenomenology in the telecommunications sector. One of them is the widespread use of the Internet, which has brought a sharp increase in traffic, forcing suppliers to continuously expand the capacity of networks. In the near future, Internet will be composed of long-range highspeed optical networks; a number of wireless networks at the edge; and, in between, several access technologies. Today one of the main problems of the Internet is the bottleneck in the access segment. To address this issue the Passive Optical Networks (PONs) are very likely to succeed, due to their simplicity, low-cost, and increased bandwidth. A PON is made up of fiber optic cabling and passive splitters and couplers that distribute an optical signal to connectors that terminate each fiber segment. Among the different PON technologies, the Ethernet-PON (EPON) is a great alternative to satisfy operator and user needs, due to its cost, flexibility and interoperability with other technologies. One of the most interesting challenges in such technologies relates to the scheduling and allocation of resources in the upstream (shared) channel, i.e., the resource management. The aim of this thesis is to study and evaluate current contributions and propose new efficient solutions to address the resource management issues mainly in EPON. Key issues in this context are future end-user needs, quality of service (QoS) support, energy-saving and optimized service provisioning for real-time and elastic flows. This thesis also identifies research opportunities, issue recommendations and proposes novel mechanisms associated with access networks based on optical fiber technologies.Postprint (published version

Analysis of passive optical network

With the increasing development of fiber optic communication technology, the needs of higher transmission rates, longer transmission distance, and greater transmission bandwidth are much stronger. Telecommunication companies tried to fulfil those needs by constantly reviewing and testing the performances of the applied Fiber Access Network System. This research is based on how we can design and analyses the optical fiber communication system. In this analysis, the Passive Optical Network architecture is planned to meet the requirements of the most common system which is Gigabit Passive Optical Networks (GPON). This design is simulated using the software OptiSystem 14.0 taking the realistic parameters of existing systems into account. According to The Full-Service Access Network (FSAN) the industry has converged on 2.488 gigabits per second (Gbit/s) of downstream bandwidth, and 1.244 Gbit/s of upstream bandwidth as the best solution to implement. The FSAN and ITU-T guide the efforts of user needs assessment for bandwidth to plan for smooth network upgrade that meets the user demand with optimal investment and let the user have many options to choose the bandwidth according to the needs within the financial grow capability. Additionally, on this project, a GPON design coexists with the new generation of NG-PON1 and NG-PON2 has been simulated and studied to analysis and compare using Optisystem which is a simulation system. The research stands for designing, testing the performance of the optical network by compensate minimum bit error and improve quality factor of the network. This model is designed from a data that has been obtained from existing networks in published papers and the main focus is to testing performance a GPON network in software Optisystem of the optical network by the minimum amount of BER, Q-factor, and power budget to achieve the requirement of the customers of the network

Optical switching for dynamic distribution of wireless-over-fiber signals in active optical networks

El continuo crecimiento de ancho de banda demandado por los usuarios finales está provocando una gran exigencia sobre las redes de acceso. Estas exigencias sobre las redes de acceso, que principalmente emplean tecnologías inalámbricas, están migrando hacia el dominio óptico con el fin de soportar estos altos requerimientos de ancho de banda. Dependiendo de los requerimientos y características de los usuarios finales, las redes de acceso óptico han evolucionado en diferentes direcciones. En entornos residenciales y urbanos los usuarios demandan conexiones fijas de alta capacidad y bajo coste. Las redes ópticas pasivas (PON) han cumplido estos requerimiento y son las tecnologías elegidas por los operadores. En los entornos empresariales, en los cuales la calidad y la seguridad son piezas clave, las redes ópticas activas han encontrado su hueco proveyendo flexibilidad, adaptabilidad, alto rendimiento y al mismo tiempo dando soporte a sistemas de control de redes. Los proveedores de equipos están ahora girando su vista hacia nuevos mercados, donde soluciones ópticas puede ser usado eficientemente. El transporte de datos de redes de móviles (o mobile backhaul en ingles) es un mercado que se ha convertido en objetivo principal, ya que el tráfico inalámbrico está creciendo exponencialmente. Nuevos dispositivos, junto a las aplicaciones de gran consumo de ancho de banda, son los principales motivos de este crecimiento. Las tecnologías de banda base puede soportar sobradamente mobile backhaul a las actuales velocidades de transmisión. Sin embargo, debido a la ubicación de nuevas licencias libres disponibles en la banda de frecuencias y el desarrollo de las tecnologías radio a través de fibra permitiendo generación, distribución y recepción óptica de señales, la migración hacia escenarios en los que se use señales inalámbricas a través de fibra son mas probables. Además, teniendo en cuenta aspectos como la seguridad y alta movilidad de los usuarios, todo parece indicar que soluciones activas son más atractivas, siempre y cuando que los consumos de energía se mantengan dentro de límites razonables. En esta tesis, se diseñó una red óptica de acceso basada en tecnologías de radio a través de fibra. El bloque principal de la red fue un conmutador óptico basado en componentes activos (amplificadores ópticos semiconductores); el resto de la red fue diseñada acorde a la distribución por canales del conmutador óptico. Utilizando este conmutador óptico, se realizó una validación experimental de la red. El experimento consistió en una implementación de un sistema de cuatro canales operando en la banda de frecuencia WiMax y empleando una modulación llamada multiplexado de división ortogonal en frecuencia (OFDM) a 625Mb/s por canal. La información fue enviada a través de 20 km de fibra óptica, y el redireccionamiento de la señal fue llevado a cabo por un conmutador de 1 entrada y 16 salidas. El resultado es una degradación imperceptible de la señal en cada canal en el mejor y en mejor escenario en términos de interferencia entre canales. Este sistema cumple con los requisitos de una red de acceso activa para señales de radio a través de una red de acceso óptica

Supporting Diverse Customers and Prioritized Traffic in Next-Generation Passive Optical Networks

The already high demand for more bandwidth usage has been growing rapidly. Access network traffic is usually bursty in nature and the present traffic trend is mostly video-dominant. This motivates the need for higher transmission rates in the system. At the same time, the deployment costs and maintenance expenditures have to be reasonable. Therefore, Passive Optical Networks (PON) are considered promising next-generation access technologies. As the existing PON standards are not suitable to support future-PON services and applications, the FSAN (Full Service Access Network) group and the ITU-T (Telecommunication Standardization Sector of the International Telecommunication Union) have worked on developing the NG- PON2 (Next Generation PON 2) standard. Resource allocation is a fundamental task in any PON and it is necessary to have an efficient scheme that reduces delay, maximizes bandwidth usage, and minimizes the resource wastage. A variety of DBA (Dynamic Bandwidth Allocation) and DWBA (Dynamic Wavelength and Bandwidth Allocation) algorithms have been proposed which are based on different PONs (e.g. EPON, GPON, XG-PON, 10G- EPON, etc.). But to our knowledge, no DWBA scheme for NG-PON2 system, with diverse customers and prioritized traffic, has been proposed yet. In this work, this problem is addressed and five different dynamic wavelength and bandwidth allocation (DWBA) schemes are proposed. First, mixed integer linear programming (MILP) models are developed to minimize the total delay of the high priority data. Due to the MILP’s high computational complexity, heuristic algorithms are developed based on the MILP model insights. The five heuristics algorithms are: No Block-Split Heuristic (NBH), Equal Block-Split Heuristic (EBH), Priority Based No Block-Split Heuristic (P-NBH), Priority Based Equal Block-Split Heuristic (P-EBH), and Priority Based Decider Block-Split Heuristic (P-DBH). Six priority classes of requests are introduced with the goal of minimizing the total delay for the high priority data and to lessen the bandwidth wastage of the system. Finally, experiments for the performance evaluation of the five DWBA schemes are conducted. The results show that P-NBH, P-EBH, P-DBH schemes show a 47.63% less delay and 30% of less bandwidth wastage on average for the highest priority data transmission than the schemes without priority support (NBH and EBH). Among these five schemes, NBH method has the highest delay, whereas EBH and P-EBH waste more bandwidth than the other schemes. P-DBH is the most efficient among the five because this scheme offers the lowest delay for high priority data and the minimum bandwidth wastage for lower priority ones. Adviser: Byrav Ramamurth

Fibra óptica na rede de acesso: cenários de evolução

Mestrado em Engenharia Electrónica e TelecomunicaçõesCom o aumento da necessidade dos consumidores disporem de uma crescente largura de banda, em virtude dos serviços serem tecnologicamente mais avançados, a procura de novas soluções para redes de acesso de fibra óptica cresce. A nova geração de redes de acesso (NGA: Next Generation Access Networks) vai permitir a implementação de aplicações já existentes e fornecer uma maior largura de banda que será capaz de abrir novos horizontes a nível dos serviços, oferecendo uma qualidade de serviço superior e uma redução de degradações como a latência ou a taxa de contenção. Ao dimensionar redes de acesso de fibra óptica é imperativo ponderar os aspectos práticos das suas implementações: opções arquitecturais, limitações de desempenho de equipamentos nos diferentes segmentos da rede, planos de instalação e até mesmo o comportamento dos mercados. Sendo assim, é preciso continuar o processo de evolução e descobrir novas soluções que permitam superar estas limitações. Para que isso seja possível será aqui apresentado um estudo que pretende indicar possíveis caminhos para a próxima geração de redes combatendo as limitações das arquitecturas actuais tentando obter uma direcção para os próximos anos. Esta dissertação foi desenvolvida com o objectivo de analisar a organização e a estrutura das actuais redes de telecomunicações, as suas tecnologias, arquitecturas e soluções de rede, adoptando potenciais cenários de evolução que utilizam a fibra óptica como meio físico de transmissão.With the increasing need for consumers to benefit from an increased bandwidth, in virtue of the services being technologically more advanced, the demand of new solutions for access networks grows. The Next Generation Access Networks will allow the implementation of existing applications and provide a higher bandwidth that will be able to open new horizons for services by offering a quality of service and a reduction of degradations such as latency or contention rate. When dimensioning an access network is imperative to consider the practicalities of their implementation: architectural options, performance limitations of equipment, design plans and even the market’s behavior. Therefore, we must continue to progress in finding new solutions to address these issues. To make this possible, a study of next-generation networks will be presented here, presenting the options available to tackle the existing constraints and to try to get a direction for the following years. This project was developed in order to analyze the organization and structure of the current telecommunications networks, their technologies, architectures and solutions, considering potential growth scenarios that use optical fiber as the physical transmission medium

Dynamic bandwidth allocation algorithms with non-zero laser tuning time in TWDM passive optical networks

The goal of this document is to analyse the functionality of Passive Optical Networks (PONs). The reason for focusing on these technique networks is due to their high efficiency in terms of high bandwidth, high rate, low energy consumption and low cost. PONs are composed of Optical Network Unit (ONU), Optical Line Terminal (OLT) and passive elements (splitters/combiners, optical fibres…). Specifically, this document analyses Ethernet Passive Optical Networks (EPONs) defined by Institute of Electrical and Electronics Engineers (IEEE) in the IEEE 802.3ah standard although there is another standard. The main difference between them is the framing protocol, being the EPONs compliance with Ethernet frames. The first PONs used a single optical carrier. That means that upstream channel is a shared resource and a scheduling is needed to avoid collisions between users’ transmissions, by using Time-Division Multiple Access (TDMA). In PONs the OLT plays an important paper, since it is the responsible of the dynamic bandwidth allocation (DBA). The DBA agent in the OLT has an algorithm that schedules the users’ transmissions. Since the deployment of the first PONs, the requirements of the users have increased, and users need high bandwidth and high rate. Thus, a new generation of PONs (NG-PON) have been designed. These next generation of PONs are multicarrier. That means that upstream channel that is a shared resource needs a Medium Access Protocol (MAC) based on wavelength/time-sharing known as Wavelength-Time Division Multiple Access (WTDMA). The algorithm placed on the DBA agent in the OLT increases its complexity. The algorithm should be able to schedule the transmissions based on time and wavelength. In the new generation of PON, in order to change the transmission wavelength, the ONUs have to retune their lasers. This wavelength change causes a tuning time delay. The target of this project is to design, implement and analyse an algorithm based on WTDMA and able to consider the tuning time delay and to minimize the global average delay of the system. Besides, the algorithm should apply the Just-In-Time (JIT) technique for increasing the system efficiency. All the simulations and implementations have been performed in the OPNET simulator, over a base code based on multicarrier EPON created by another student. In order to implement our algorithm a previous upgrading work has been realized for running the model and adapting it for the new requirements. We have succeeded in simulating an EPON with 4 channels where every channel has a 1 Gbps of bandwidth in OPNET simulator. In EPON we have introduced a laser tuning time control. Finally, we have implemented the designed algorithm. The algorithm schedules efficiently the network transmissions considering the laser tuning time delay. We have successfully simulated an EPON with 4 carriers, with 1 Gbps per carrier. Finally, we have implemented an algorithm able to schedule efficiently the network transmissions considering the laser tuning time delay