Programmable filterless network architecture based on optical white boxes

We propose and evaluate a novel architecture enabling high-capacity, resource efficient and agile elastic optical networks. It is based on sliceable bandwidth-variable transponders and optical white box switches which route optical signals without filtering them. Instead of using active filtering components, each node is equipped with an optical white box based on a programmable optical switch that serves as an optical backplane. It provides interconnections between input/output ports and passive splitters and couplers. Due to signal broadcast and the absence of filtering (so-called drop-and-waste transmission), some of the signals appear on unintended links which can lead to an overhead in spectrum usage. To address this issue, we formulate the problem of signal routing, modulation format and spectrum assignment in programmable filterless networks based on optical white boxes as an integer linear program (ILP) with the objective to minimize the total spectrum usage. Simulation results indicate that our proposed solution obtains a beneficial tradeoff between component usage and spectrum consumption, using a drastically lower number of active switching elements than the conventional networks based on hard-wired reconfigurable add/drop multiplexers, and lowering the maximum used frequency slot by up to 48% compared to existing passive filterless networks

Design of Programmable Filterless Optical Networks

We present the main operating principles and guidelines for the design of programmable filterless networks

Cost-Effective and Optimized Optical Networks Based on Point to Multipoint Transceivers

The rapid increase in internet traffic due to widespread internet access and technological advancements such as 5G, cloud omputing, Internet of Things (IoT), and virtual reality has created a complex environment for network operators and internet service providers. To ensure profitability and improve user experience, these entities need to implement long-term strategies that optimize network planning, cost, and efficiency. These strategies should consider market demands, evolving technologies, and prioritize resource utilization, customer expansion, service quality, and cost reduction. The thesis mainly focuses on network design and optimization. It begins with a concise introduction to optical transport network elements and the primary motivations for networking. The use of dense wavelength division multiplexing (DWDM) systems is described, along with the conventional network problems associated with routing and wavelength assignment, as well as routing and spectrum assignment. The thesis also includes a brief discussion on the power consumption of the Internet, with a particular focus on routers as power-hungry network components. Next, the thesis delves into the digital subcarrier multiplexing point-to-multipoint (P2MP) transceiver, explaining its architecture and function. Several optimization frameworks based on integer linear Programming (ILP) are proposed to effectively deploy P2MP transceivers in both filtered and filterless scenarios. Different protection scenarios are also explored. Furthermore, the thesis investigates a comprehensive multi-period planning scenarios that take into account evolving traffic and transceiver technology. The results demonstrate that P2MP transceivers can reduce transceiver costs by up to 35% compared to traditional point-to-point transceivers. Finally, the thesis presents a comprehensive and optimized physical design for horseshoe networks, integrating the utilization of P2MP transceivers and a filterless architecture. This design approach offers a simplified and cost-effective solution while leveraging the savingsoffered by P2MP technology

Optimal Design of Filterless Optical Networks

Filterless optical network has been widely used in recent years. The incentive of this technology is only the passive equipment will be used, which requires no electricity. By using this technology, not only the cost reductions, but also the environment preservation will be achieved. In literature, a lot of researchers studied the design of filterless optical network. But due to the complexity and scalability limits of this problem, most of the works are based on heuristic or meta-heuristic methods. We were seeking exact solutions to achieve the design of filterless optical networks. First we proposed a one step solution scheme, which combines tree decomposition and network provisioning, i.e.,routing and wavelength assignment within a single mathematical model, called CG_FOP. We propose a decomposition with two different sub-problems, which are solved alternately, in order to design an exact solution scheme. The first sub-problem generates filterless sub-nets while the second deals with their wavelength allocation. Due to the complexity of the problem, significant time will be consumed if applied our model on a large and more connected network. In order to improve the performance, we proposed Dantzig-Wolfe decomposition model, called DW_FOP in which the sub-problem consists in generating a potential filterless optical sub-network, with a directed tree topology. In this new model, single pricing problem was formed which compute the network provisioning along with wavelength assignment together. In this way, master problem would be simplified, no longer contains complicated logic to build conflicts among requests. With this approach, computation time significantly reduced. To further improve the design, we proposed a nested column generation model, called NCG_FOP, in order to speed up the solution process. We break down the solution into two level of pricing, the upper level pricing computes selected paths which assigned to granted requests, network provisioning and wavelength assignment for granted requests. The upper level pricing itself is a column generation process, which includes a lower level pricing generated improved path for each granted requests

On the Filter Narrowing Issues in Elastic Optical Networks

This paper describes the problematic filter narrowing effect in the context of next-generation elastic optical networks. First, three possible scenarios are introduced: the transition from an actual fixed-grid to a flexigrid network, the generic full flexi-grid network, and a proposal for a filterless optical network. Next, we investigate different transmission techniques and evaluate the penalty introduced by the filtering effect when considering Nyquist wavelength division multiplexing, single side-band direct-detection orthogonal frequency division multiplexing, and symbol-rate variable dual polarization quadrature amplitude modulation. Also, different approaches to compensate for the filter narrowing effect are discussed. Results show that the specific needs per each scenario can be fulfilled by the aforementioned technologies and techniques or a combination of them, when balancing performance, network reach, and cost

Exploiting optical signal analysis for autonomous communications

(English) Optical communications have been extensively investigated and enhanced in the last decades. Nowadays, they are responsible to transport all the data traffic generated around the world, from access to the core network segments. As the data traffic is increasing and changing in both type and patterns, the optical communications networks and systems need to readapt and continuous advances to face the future data traffic demands in an efficient and cost-effective way. This PhD thesis focuses on investigate and analyze the optical signals in order to extract useful knowledge from them to support the autonomous lightpath operation, as well as to lightpath characterization. The first objective of this PhD thesis is to investigate the optical transmission feasibility of optical signals based on high-order modulation formats (MF) and high symbol rates (SR) in hybrid filterless, filtered and flexible optical networks. It is expected a higher physical layer impairments impact on these kinds of optical signals that can lead to degradation of the quality of transmission. In particular, the impact of the optical filter narrowing arising from the node cascade is evaluated. The obtained simulation results for the required optical-signal-to-noise ratio in a cascade up to 10 optical nodes foresee the applicability of these kinds of optical signals in such scenarios. By using high-order MF and high SR, the number of the optical transponders cab be reduced, as well as the spectral efficiency is enhanced. The second objective focuses on MF and SR identification at the optical receiver side to support the autonomous lightpath operation. Nowadays, optical transmitters can generate several optical signal configurations in terms of MF and SR. To increase the autonomous operation of the optical receiver, it is desired it can autonomously recognize the MF and SR of the incoming optical signals. In this PhD thesis, we propose an accurate and low complex MF and SR identification algorithm based on optical signal analysis and minimum Euclidean distance to the expected points when the received signals are decoded with several available MF and SR. The extensive simulation results show remarkable accuracy under several realistic lightpath scenarios, based on different fiber types, including linear and nonlinear noise interference, as well as in single and multicarrier optical systems. The final objective of this PhD thesis is the deployment of a machine learning-based digital twin for optical constellations analysis and modeling. An optical signal along its lightpath in the optical network is impaired by several effects. These effects can be linear, e.g., the noise coming from the optical amplification, or nonlinear ones, e.g., the Kerr effects from the fiber propagation. The optical constellations are a good source of information regarding these effects, both linear and nonlinear. Thus, by an accurate and deep analysis of the received optical signals, visualized in optical constellations, we can extract useful information from them to better understand the several impacts along the crossed lightpath. Furthermore, by learning the different impacts from different optical network elements on the optical signal, we can accurately model it in order to create a partial digital twin of the optical physical layer. The proposed digital twin shows accurate results in modeled lightpaths including both linear and nonlinear interference noise, in several lightpaths configuration, i.e., based on different kind of optical links, optical powers and optical fiber parameters. In addition, the proposed digital twin can be useful to predict quality of transmission metrics, such as bit error rate, in typical lightpath scenarios, as well as to detect possible misconfigurations in optical network elements by cooperation with the software-defined networking controller and monitoring and data analytics agents.(Español) Las comunicaciones ópticas han sido ampliamente investigadas y mejoradas en las últimas décadas. En la actualidad, son las encargadas de transportar la mayoría del tráfico de datos que se genera en todo el mundo, desde el acceso hasta los segmentos de la red troncal. A medida que el tráfico de datos aumenta y cambia tanto en tipo como en patrones, las redes y los sistemas de comunicaciones ópticas necesitan readaptarse y avanzar continuamente para, de una manera eficiente y rentable, hacer frente a las futuras demandas de tráfico de datos. Esta tesis doctoral se centra en investigar y analizar las señales ópticas con el fin de extraer de ellas conocimiento útil para apoyar el funcionamiento autónomo de las conexiones ópticas, así como para su caracterización. El primer objetivo de esta tesis doctoral es investigar la viabilidad de transmisión de señales ópticas basadas en formatos de modulación de alto orden y altas tasas de símbolos en redes ópticas híbridas con y sin filtros. Se espera un mayor impacto de las degradaciones de la capa física en este tipo de señales ópticas que pueden conducir a la degradación de la calidad de transmisión. En particular, se evalúa el impacto de la reducción del ancho de banda del filtro óptico que surge tras atravesar una cascada de nodos. Los resultados de simulación obtenidos para la relación señal óptica/ruido requerida en una cascada de hasta 10 nodos ópticos prevén la aplicabilidad de este tipo de señales ópticas en tales escenarios. Mediante el uso de modulación de alto orden y altas tasas de símbolos, se reduce el número de transpondedores ópticos y se mejora la eficiencia espectral. El segundo objetivo se centra en la identificación de formatos de modulación y tasas de símbolos en el lado del receptor óptico para respaldar la operación autónoma de la conexión óptica. Para aumentar el funcionamiento autónomo del receptor óptico, se desea que pueda reconocer de forma autónoma la configuración de las señales ópticas entrantes. En esta tesis doctoral, proponemos un algoritmo de identificación de formatos de modulación y tasas de símbolos preciso y de baja complejidad basado en el análisis de señales ópticas cuando las señales recibidas se decodifican con varios formatos de modulación y tasas de símbolos disponibles. Los extensos resultados de la simulación muestran una precisión notable en varios escenarios realistas, basados en diferentes tipos de fibra, incluida la interferencia de ruido lineal y no lineal, así como en sistemas ópticos de portadora única y múltiple. El objetivo final de esta tesis doctoral es el despliegue de un gemelo digital basado en aprendizaje automático para el análisis y modelado de constelaciones ópticas. Una señal óptica a lo largo de su trayectoria en la red óptica se ve afectada por varios efectos, pueden ser lineales o no lineales. Las constelaciones ópticas son una buena fuente de información sobre estos efectos, tanto lineales como no lineales. Por lo tanto, mediante un análisis preciso y profundo de las señales ópticas recibidas, visualizadas en constelaciones ópticas, podemos extraer información útil de ellas para comprender mejor los diversos impactos a lo largo del camino propagado. Además, al aprender los diferentes impactos de los diferentes elementos de la red óptica en la señal óptica, podemos modelarla con precisión para crear un gemelo digital parcial de la camada física óptica. El gemelo digital propuesto muestra resultados precisos en conexiones que incluyen ruido de interferencia tanto lineal como no lineal, en varias configuraciones basados en diferentes tipos de enlaces ópticos, potencias ópticas y parámetros de fibra óptica. Además, el gemelo digital propuesto puede ser útil para predecir la calidad de las métricas de transmisión así como para detectar posibles errores de configuración en los elementos de la red óptica mediante la cooperación con el controlador de red, el monitoreo y agentes de análisis de datosPostprint (published version

Autonomous Security Management in Optical Networks

The paper describes the Optical Security Manager module and focuses on the role of Machine Learning (ML) techniques. Issues related to the accuracy, run-time complexity and interpretability of ML outputs are described and coping strategies outlined