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

Contributions towards softwarization and energy saving in passive optical networks

Ths thesis is a result of contributions to optimize and improve the network management systme and power consumption in Passive Optical Network (PON). Passive Optical Network elements such as Optical Line Terminal (OLT) and Optical Network Units (ONUs) are currently managed by inflexible legacy network management systems. Software-Defined Networking (SDN) is a new networking paradigm that improves the operation and management of networks by decoupling control plane from data plane. Currently, network management in PON networks is not always automated nor normalized. One goal of the researchers in optical networking is to improve the programmability, efficiency, and global optimization of network operations, in order to minimize both Capital Expenditure (CAPEX) and Operational Expenditure (OPEX) by reducing the complexity of devices and its operation. Therefore, it makes sense to use an SDN approach in order to manage the passive optical network functionalities and migrating must of the upper layer functions to the SDN controller. Many approaches have already addressed the topic of applying the SDN architecture in PON networks. However; the focus was usually on facilitating the deployment of SDN-based service and so Service Interoperability remains unexplored in detail. The main challenge toward this goal is how to make compatible the synchronous nature of the EPON media access control protocols with the asynchronous architecture of SDN, and in particular, OpenFlow. In our proposed architecture, the OLT is partially virtualized and some of its functionalities are allocated to the core network management system, while the OLT itself is replaced by an OpenFlow switch. A new MultiPoint MAC Control (MPMC) sublayer extension based on the OpenFlow protocol is presented. The OpenFlow switch is extended with synchronous ports to retain the time-critical nature of the EPON network. Our simulation-based results demonstrate the effectiveness of the new architecture, while retaining a similar (or improved) performance in term of delay and throughput when compared to legacy PONs. Nowadays, many researchers are working simultaneously to develop power saving techniques and improves energy efficiency in the PON network, and since the contribution of access networks to the global energy consumption is large, energy efficiency has become an increasingly important requirement in designing access networks. Therefore, energy-saving approaches are being investigated to provide high performance and consume less energy. Several techniques have been proposed to increase energy efficiency in PON networks. Such techniques are related to the centeralized DBA but the advantage of power saving in a distributed DBA remains untouched. We present a distributed energy-efficient Dynamic Bandwidth Allocation (DBA) algorithm for both the upstream and downstream channels of EPON to improve energy efficiency in EPON networks. The proposed algorithm analyzes the queue status of the ONUs and OLT in order to power-off the transmitter and/or receiver of an ONU whenever there is no upstream or downstream traffic. We have been able to combine the advantage of a distributed DBA such as DDSPON (a smaller packet delay, due to the shorter time needed by DDSPON to allocate the transmission slots) and the energy-saving features (that come at a price of longer packet delays due to the fact that switching off the transmitters make the packet queues grow). Our proposed DBA algorithm minimizes the ONU energy consumption across a wide range of network loads, while maintaining at an acceptable level the penalty introduced in terms of channel utilization and packet delay.Las contribuciones de esta tesis se centran en mejorar el sistema de gestión de red y el consumo de energía en redes de acceso ópticas pasivas (PON). Los elementos de las redes PON, como el terminal de línea óptica (OLT) y las unidades de red ópticas (ONU), se gestionan actualmente mediante sistemas poco flexibles. El nuevo paradigma de redes definidas por software (SDN) mejora la gestión de redes al desacoplar el plano de control del plano de datos. Actualmente, la gestión de redes PON no está automatizada ni normalizada. Uno de los objetivos de los investigadores en redes ópticas es mejorar la programabilidad, la eficiencia y la optimización global de las operaciones de red, con el fin de minimizar tanto el gasto de capital (CAPEX) como el gasto operativo (OPEX) al reducir la complejidad de los dispositivos y su funcionamiento. Por lo tanto, tiene sentido utilizar un enfoque SDN para gestionar las funciones de red óptica pasiva y migrar algunas de las funciones PON de capas superiores al controlador SDN. Otros investigadores han estudiado esta aproximación. sin embargo; el enfoque generalmente estaba en facilitar la implementación del servicio basado en SDN y, por lo tanto, la interoperabilidad de los servicios permanecía sin ser explorado en detalle. El principal desafío hacia este objetivo es cómo compatibilizar la naturaleza síncrona de los protocolos de control de acceso a medios EPON con la arquitectura asíncrona de SDN y, en particular, OpenFlow. En nuestra propuesta de arquitectura, la OLT se virtualiza parcialmente y algunas de sus funcionalidades se asignan al sistema de gestión de red centralizado, mientras que la OLT se reemplaza por un conmutador OpenFlow. Proponemos una nueva extensión de la subcapa de control múltiple de MAC (MPMC) basada en el protocolo OpenFlow. El conmutador OpenFlow se amplía con puertos síncronos para asegurar la naturaleza de tiempo real de la red EPON. Nuestros resultados basados ¿¿en simulaciones demuestran la efectividad de la nueva arquitectura, al tiempo que se mantiene un rendimiento similar (o mejorado) en términos de retardos y rendimiento en comparación con las PON clásicas. Por otro lado, se están desarrollando técnicas de ahorro de energía y mejora de la eficiencia energética en redes PON, y dado que la contribución de las redes de acceso al consumo total de energía es importante, la eficiencia energética se ha convertido en un requisito cada vez más importante. Se han propuesto varias técnicas por parte de otros autores para aumentar la eficiencia energética en las redes PON, relacionadas con algoritmos DBA (Dynamic Bandwidth Allocation) centralizados, pero las ventaja del ahorro de energía en un DBA distribuido no se ha explorado todavía. Por ello nuestra segunda contiribución es un algoritmo distribuido de asignación dinámica de ancho de banda energéticamente eficiente tanto para los canales ascendentes como descendentes de EPON para mejorar la eficiencia energética en las redes EPON. El algoritmo propuesto analiza el estado de cola de las ONU y la OLT para apagar el transmisor y/o el receptor de una ONU cuando no hay tráfico en sentido ascendente o descendente. Hemos podido combinar la ventaja de un DBA distribuido como DDSPON (que asegura retardos más pequeños, debido al menor tiempo que DDSPON necesita para asignar las ranuras de transmisión) y las características de ahorro de energía (al precio de tener retardos de paquete más grandes debido al hecho de que apagar los transmisores hace que las colas de paquetes crezcan). Nuestro algoritmo de DBA propuesto minimiza el consumo de energía de la ONU en una amplia gama de cargas de red, mientras mantiene a un nivel aceptable la penalización introducida en términos de utilización del canal y retardos

Contributions towards softwarization and energy saving in passive optical networks

Ths thesis is a result of contributions to optimize and improve the network management systme and power consumption in Passive Optical Network (PON). Passive Optical Network elements such as Optical Line Terminal (OLT) and Optical Network Units (ONUs) are currently managed by inflexible legacy network management systems. Software-Defined Networking (SDN) is a new networking paradigm that improves the operation and management of networks by decoupling control plane from data plane. Currently, network management in PON networks is not always automated nor normalized. One goal of the researchers in optical networking is to improve the programmability, efficiency, and global optimization of network operations, in order to minimize both Capital Expenditure (CAPEX) and Operational Expenditure (OPEX) by reducing the complexity of devices and its operation. Therefore, it makes sense to use an SDN approach in order to manage the passive optical network functionalities and migrating must of the upper layer functions to the SDN controller. Many approaches have already addressed the topic of applying the SDN architecture in PON networks. However; the focus was usually on facilitating the deployment of SDN-based service and so Service Interoperability remains unexplored in detail. The main challenge toward this goal is how to make compatible the synchronous nature of the EPON media access control protocols with the asynchronous architecture of SDN, and in particular, OpenFlow. In our proposed architecture, the OLT is partially virtualized and some of its functionalities are allocated to the core network management system, while the OLT itself is replaced by an OpenFlow switch. A new MultiPoint MAC Control (MPMC) sublayer extension based on the OpenFlow protocol is presented. The OpenFlow switch is extended with synchronous ports to retain the time-critical nature of the EPON network. Our simulation-based results demonstrate the effectiveness of the new architecture, while retaining a similar (or improved) performance in term of delay and throughput when compared to legacy PONs. Nowadays, many researchers are working simultaneously to develop power saving techniques and improves energy efficiency in the PON network, and since the contribution of access networks to the global energy consumption is large, energy efficiency has become an increasingly important requirement in designing access networks. Therefore, energy-saving approaches are being investigated to provide high performance and consume less energy. Several techniques have been proposed to increase energy efficiency in PON networks. Such techniques are related to the centeralized DBA but the advantage of power saving in a distributed DBA remains untouched. We present a distributed energy-efficient Dynamic Bandwidth Allocation (DBA) algorithm for both the upstream and downstream channels of EPON to improve energy efficiency in EPON networks. The proposed algorithm analyzes the queue status of the ONUs and OLT in order to power-off the transmitter and/or receiver of an ONU whenever there is no upstream or downstream traffic. We have been able to combine the advantage of a distributed DBA such as DDSPON (a smaller packet delay, due to the shorter time needed by DDSPON to allocate the transmission slots) and the energy-saving features (that come at a price of longer packet delays due to the fact that switching off the transmitters make the packet queues grow). Our proposed DBA algorithm minimizes the ONU energy consumption across a wide range of network loads, while maintaining at an acceptable level the penalty introduced in terms of channel utilization and packet delay.Las contribuciones de esta tesis se centran en mejorar el sistema de gestión de red y el consumo de energía en redes de acceso ópticas pasivas (PON). Los elementos de las redes PON, como el terminal de línea óptica (OLT) y las unidades de red ópticas (ONU), se gestionan actualmente mediante sistemas poco flexibles. El nuevo paradigma de redes definidas por software (SDN) mejora la gestión de redes al desacoplar el plano de control del plano de datos. Actualmente, la gestión de redes PON no está automatizada ni normalizada. Uno de los objetivos de los investigadores en redes ópticas es mejorar la programabilidad, la eficiencia y la optimización global de las operaciones de red, con el fin de minimizar tanto el gasto de capital (CAPEX) como el gasto operativo (OPEX) al reducir la complejidad de los dispositivos y su funcionamiento. Por lo tanto, tiene sentido utilizar un enfoque SDN para gestionar las funciones de red óptica pasiva y migrar algunas de las funciones PON de capas superiores al controlador SDN. Otros investigadores han estudiado esta aproximación. sin embargo; el enfoque generalmente estaba en facilitar la implementación del servicio basado en SDN y, por lo tanto, la interoperabilidad de los servicios permanecía sin ser explorado en detalle. El principal desafío hacia este objetivo es cómo compatibilizar la naturaleza síncrona de los protocolos de control de acceso a medios EPON con la arquitectura asíncrona de SDN y, en particular, OpenFlow. En nuestra propuesta de arquitectura, la OLT se virtualiza parcialmente y algunas de sus funcionalidades se asignan al sistema de gestión de red centralizado, mientras que la OLT se reemplaza por un conmutador OpenFlow. Proponemos una nueva extensión de la subcapa de control múltiple de MAC (MPMC) basada en el protocolo OpenFlow. El conmutador OpenFlow se amplía con puertos síncronos para asegurar la naturaleza de tiempo real de la red EPON. Nuestros resultados basados ¿¿en simulaciones demuestran la efectividad de la nueva arquitectura, al tiempo que se mantiene un rendimiento similar (o mejorado) en términos de retardos y rendimiento en comparación con las PON clásicas. Por otro lado, se están desarrollando técnicas de ahorro de energía y mejora de la eficiencia energética en redes PON, y dado que la contribución de las redes de acceso al consumo total de energía es importante, la eficiencia energética se ha convertido en un requisito cada vez más importante. Se han propuesto varias técnicas por parte de otros autores para aumentar la eficiencia energética en las redes PON, relacionadas con algoritmos DBA (Dynamic Bandwidth Allocation) centralizados, pero las ventaja del ahorro de energía en un DBA distribuido no se ha explorado todavía. Por ello nuestra segunda contiribución es un algoritmo distribuido de asignación dinámica de ancho de banda energéticamente eficiente tanto para los canales ascendentes como descendentes de EPON para mejorar la eficiencia energética en las redes EPON. El algoritmo propuesto analiza el estado de cola de las ONU y la OLT para apagar el transmisor y/o el receptor de una ONU cuando no hay tráfico en sentido ascendente o descendente. Hemos podido combinar la ventaja de un DBA distribuido como DDSPON (que asegura retardos más pequeños, debido al menor tiempo que DDSPON necesita para asignar las ranuras de transmisión) y las características de ahorro de energía (al precio de tener retardos de paquete más grandes debido al hecho de que apagar los transmisores hace que las colas de paquetes crezcan). Nuestro algoritmo de DBA propuesto minimiza el consumo de energía de la ONU en una amplia gama de cargas de red, mientras mantiene a un nivel aceptable la penalización introducida en términos de utilización del canal y retardos.Postprint (published version

An Innovative RAN Architecture for Emerging Heterogeneous Networks: The Road to the 5G Era

The global demand for mobile-broadband data services has experienced phenomenal growth over the last few years, driven by the rapid proliferation of smart devices such as smartphones and tablets. This growth is expected to continue unabated as mobile data traffic is predicted to grow anywhere from 20 to 50 times over the next 5 years. Exacerbating the problem is that such unprecedented surge in smartphones usage, which is characterized by frequent short on/off connections and mobility, generates heavy signaling traffic load in the network signaling storms . This consumes a disproportion amount of network resources, compromising network throughput and efficiency, and in extreme cases can cause the Third-Generation (3G) or 4G (long-term evolution (LTE) and LTE-Advanced (LTE-A)) cellular networks to crash. As the conventional approaches of improving the spectral efficiency and/or allocation additional spectrum are fast approaching their theoretical limits, there is a growing consensus that current 3G and 4G (LTE/LTE-A) cellular radio access technologies (RATs) won\u27t be able to meet the anticipated growth in mobile traffic demand. To address these challenges, the wireless industry and standardization bodies have initiated a roadmap for transition from 4G to 5G cellular technology with a key objective to increase capacity by 1000Ã? by 2020 . Even though the technology hasn\u27t been invented yet, the hype around 5G networks has begun to bubble. The emerging consensus is that 5G is not a single technology, but rather a synergistic collection of interworking technical innovations and solutions that collectively address the challenge of traffic growth. The core emerging ingredients that are widely considered the key enabling technologies to realize the envisioned 5G era, listed in the order of importance, are: 1) Heterogeneous networks (HetNets); 2) flexible backhauling; 3) efficient traffic offload techniques; and 4) Self Organizing Networks (SONs). The anticipated solutions delivered by efficient interworking/ integration of these enabling technologies are not simply about throwing more resources and /or spectrum at the challenge. The envisioned solution, however, requires radically different cellular RAN and mobile core architectures that efficiently and cost-effectively deploy and manage radio resources as well as offload mobile traffic from the overloaded core network. The main objective of this thesis is to address the key techno-economics challenges facing the transition from current Fourth-Generation (4G) cellular technology to the 5G era in the context of proposing a novel high-risk revolutionary direction to the design and implementation of the envisioned 5G cellular networks. The ultimate goal is to explore the potential and viability of cost-effectively implementing the 1000x capacity challenge while continuing to provide adequate mobile broadband experience to users. Specifically, this work proposes and devises a novel PON-based HetNet mobile backhaul RAN architecture that: 1) holistically addresses the key techno-economics hurdles facing the implementation of the envisioned 5G cellular technology, specifically, the backhauling and signaling challenges; and 2) enables, for the first time to the best of our knowledge, the support of efficient ground-breaking mobile data and signaling offload techniques, which significantly enhance the performance of both the HetNet-based RAN and LTE-A\u27s core network (Evolved Packet Core (EPC) per 3GPP standard), ensure that core network equipment is used more productively, and moderate the evolving 5G\u27s signaling growth and optimize its impact. To address the backhauling challenge, we propose a cost-effective fiber-based small cell backhaul infrastructure, which leverages existing fibered and powered facilities associated with a PON-based fiber-to-the-Node/Home (FTTN/FTTH)) residential access network. Due to the sharing of existing valuable fiber assets, the proposed PON-based backhaul architecture, in which the small cells are collocated with existing FTTN remote terminals (optical network units (ONUs)), is much more economical than conventional point-to-point (PTP) fiber backhaul designs. A fully distributed ring-based EPON architecture is utilized here as the fiber-based HetNet backhaul. The techno-economics merits of utilizing the proposed PON-based FTTx access HetNet RAN architecture versus that of traditional 4G LTE-A\u27s RAN will be thoroughly examined and quantified. Specifically, we quantify the techno-economics merits of the proposed PON-based HetNet backhaul by comparing its performance versus that of a conventional fiber-based PTP backhaul architecture as a benchmark. It is shown that the purposely selected ring-based PON architecture along with the supporting distributed control plane enable the proposed PON-based FTTx RAN architecture to support several key salient networking features that collectively significantly enhance the overall performance of both the HetNet-based RAN and 4G LTE-A\u27s core (EPC) compared to that of the typical fiber-based PTP backhaul architecture in terms of handoff capability, signaling overhead, overall network throughput and latency, and QoS support. It will also been shown that the proposed HetNet-based RAN architecture is not only capable of providing the typical macro-cell offloading gain (RAN gain) but also can provide ground-breaking EPC offloading gain. The simulation results indicate that the overall capacity of the proposed HetNet scales with the number of deployed small cells, thanks to LTE-A\u27s advanced interference management techniques. For example, if there are 10 deployed outdoor small cells for every macrocell in the network, then the overall capacity will be approximately 10-11x capacity gain over a macro-only network. To reach the 1000x capacity goal, numerous small cells including 3G, 4G, and WiFi (femtos, picos, metros, relays, remote radio heads, distributed antenna systems) need to be deployed indoors and outdoors, at all possible venues (residences and enterprises)

Optimizing resource allocation in next-generation optical access networks

To meet rapidly increasing traffic demands caused by the popularization of Internet and the spouting of bandwidth-demanding applications, Passive Optical Networks (PONs) exploit the potential capacities of optical fibers, and are becoming promising future-proof access network technologies. On the other hand, for a broader coverage area and higher data rate, integrated optical and wireless access is becoming a future trend for wireless access. This thesis investigates three next-generation access networks: Time Division Multiplexing (TDM) PONs, Wavelength Division Multiplexing (WDM) PONs, and WDM Radio-Over-Fiber (RoF) Picocellular networks. To address resource allocation problems in these three networks, this thesis first investigates respective characteristics of these networks, and then presents solutions to address respective challenging problems in these networks. In particular, three main problems are addressed: arbitrating time allocation among different applications to guarantee user quality of experience (QoE) in TDM PONs, scheduling wavelengths optimally in WDM PONs, and jointly allocating fiber and radio resources in WDM RoF Picocellular networks. In-depth theoretical analysis and extensive simulations have been performed in evaluating and demonstrating the performances of the proposed schemes

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.

Topics in access, storage, and sensor networks

In the first part of this dissertation, Data Over Cable Service Interface Specification (DOCSIS) and IEEE 802.3ah Ethernet Passive Optical Network (ETON), two access networking standards, are studied. We study the impact of two parameters of the DOCSIS protocol and derive the probability of message collision in the 802.3ah device discovery scheme. We survey existing bandwidth allocation schemes for EPONs, derive the average grant size in one such scheme, and study the performance of the shortest-job-first heuristic. In the second part of this dissertation, we study networks of mobile sensors. We make progress towards an architecture for disconnected collections of mobile sensors. We propose a new design abstraction called tours which facilitates the combination of mobility and communication into a single design primitive and enables the system of sensors to reorganize into desirable topologies alter failures. We also initiate a study of computation in mobile sensor networks. We study the relationship between two distributed computational models of mobile sensor networks: population protocols and self-similar functions. We define the notion of a self-similar predicate and show when it is computable by a population protocol. Transition graphs of population protocols lead its to the consideration of graph powers. We consider the direct product of graphs and its new variant which we call the lexicographic direct product (or the clique product). We show that invariants concerning transposable walks in direct graph powers and transposable independent sets in graph families generated by the lexicographic direct product are uncomputable. The last part of this dissertation makes contributions to the area of storage systems. We propose a sequential access detect ion and prefetching scheme and a dynamic cache sizing scheme for large storage systems. We evaluate the cache sizing scheme theoretically and through simulations. We compute the expected hit ratio of our and competing schemes and bound the expected size of our dynamic cache sufficient to obtain an optimal hit ratio. We also develop a stand-alone simulator for studying our proposed scheme and integrate it with an empirically validated disk simulator

Digital signal processing optical receivers for the mitigation of physical layer impairments in dynamic optical networks

IT IS generally believed by the research community that the introduction of complex network functions—such as routing—in the optical domain will allow a better network utilisation, lower cost and footprint, and a more efficiency in energy usage. The new optical components and sub-systems intended for dynamic optical networking introduce new kinds of physical layer impairments in the optical signal, and it is of paramount importance to overcome this problem if dynamic optical networks should become a reality. Thus, the aim of this thesis was to first identify and characterise the physical layer impairments of dynamic optical networks, and then digital signal processing techniques were developed to mitigate them. The initial focus of this work was the design and characterisation of digital optical receivers for dynamic core optical networks. Digital receiver techniques allow for complex algorithms to be implemented in the digital domain, which usually outperform their analogue counterparts in performance and flexibility. An AC-coupled digital receiver for core networks—consisting of a standard PIN photodiode and a digitiser that takes samples at twice the Nyquist rate—was characterised in terms of both bit-error rate and packet-error rate, and it is shown that the packet-error rate can be optimised by appropriately setting the preamble length. Also, a realistic model of a digital receiver that includes the quantisation impairments was developed. Finally, the influence of the network load and the traffic sparsity on the packet-error rate performance of the receiver was investigated. Digital receiver technologies can be equally applied to optical access networks, which share many traits with dynamic core networks. A dual-rate digital receiver, capable of detecting optical packets at 10 and 1.25 Gb/s, was developed and characterised. The receiver dynamic range was extended by means of DC-coupling and non-linear signal clipping, and it is shown that the receiver performance is limited by digitiser noise for low received power and non-linear clipping for high received power

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