Artificial intelligence (AI) methods in optical networks: A comprehensive survey

Producción CientíficaArtificial intelligence (AI) is an extensive scientific discipline which enables computer systems to solve problems by emulating complex biological processes such as learning, reasoning and self-correction. This paper presents a comprehensive review of the application of AI techniques for improving performance of optical communication systems and networks. The use of AI-based techniques is first studied in applications related to optical transmission, ranging from the characterization and operation of network components to performance monitoring, mitigation of nonlinearities, and quality of transmission estimation. Then, applications related to optical network control and management are also reviewed, including topics like optical network planning and operation in both transport and access networks. Finally, the paper also presents a summary of opportunities and challenges in optical networking where AI is expected to play a key role in the near future.Ministerio de Economía, Industria y Competitividad (Project EC2014-53071-C3-2-P, TEC2015-71932-REDT

Evolution towards Smart Optical Networking: Where Artificial Intelligence (AI) meets the World of Photonics

Smart optical networks are the next evolution of programmable networking and programmable automation of optical networks, with human-in-the-loop network control and management. The paper discusses this evolution and the role of Artificial Intelligence (AI)

A congestion aware ant colony optimisation-based routing and wavelength assignment algorithm for transparent flexi-grid optical burst switched networks

Optical Burst Switching (OBS) over transparent exi-grid optical networks, is considered a potential solution to the increasing pressure on backbone networks due to the increase in internet use and widespread adoption of various high bandwidth applications. Both technologies allow for more e cient usage of a networks resources. However, transmissions over exi-grid networks are more susceptible to optical impairments than transmissions made over xed-grid networks, and OBS suers from high burst loss due to contention. These issues need to be solved in order to reap the full benets of both technologies. An open issue for OBS whose solution would mitigate both issues is the Routing and Wavelength Assignment (RWA) algorithm. Ant Colony Optimisation (ACO) is a method of interest for solving the RWA problem on OBS networks. This study aims to improve on current dynamic ACO-based solutions to the Routing and Wavelength Assignment problem on transparent exi-grid Optical Burst Switched networks

An ant-based algorithm for distributed routing and wavelength assignment in dynamic optical networks

Future optical communication networks are expected to change radically during the next decade. To meet the demanded bandwidth requirements, more dynamism, scalability and automatism will need to be provided. This will also require addressing issues such as the design of highly distributed control plane systems and their associated algorithms to respond to network changes very rapidly. In this work, we propose the use of an ant colony optimization (ACO) algorithm to solve the intrinsic problem of the routing and wavelength assignment (RWA) on wavelength continuity constraint optical networks. The main advantage of the protocol is its distributed nature, which provides higher survivability to network failures or traffic congestion. The protocol has been applied to a specific type of future optical network based on the optical switching of bursts. It has been evaluated through extensive simulations with very promising results, particularly on highly congested scenarios where the load balancing capabilities of the protocol become especially efficient. Results on a partially meshed network like NSFNET show that the ant-based protocol outperforms other RWA algorithms under test in terms of blocking probability without worsening other metrics such as mean route length.Peer ReviewedPostprint (published version

Optimal Control of SOAs with Artificial Intelligence for Sub-Nanosecond Optical Switching

Novel approaches to switching ultra-fast semiconductor optical amplifiers using artificial intelligence algorithms (particle swarm optimisation, ant colony optimisation, and a genetic algorithm) are developed and applied both in simulation and experiment. Effective off-on switching (settling) times of 542 ps are demonstrated with just 4.8% overshoot, achieving an order of magnitude improvement over previous attempts described in the literature and standard dampening techniques from control theory.Comment: This manuscript was accepted for publication in the IEEE/OSA Journal of Lightwave Technology on 21st June 2020. Open access code: https://github.com/cwfparsonson/soa_driving Open access data: https://doi.org/10.5522/04/12356696.v

Architectures and protocols for sub-wavelength optical networks: contributions to connectionless and connection-oriented data transport

La ràpida evolució d’Internet i l’àmplia gamma de noves aplicacions (per exemple, multimèdia, videoconferència, jocs en línia, etc.) ha fomentat canvis revolucionaris en la manera com ens comuniquem. A més, algunes d’aquestes aplicacions demanden grans quantitats de recursos d’ample de banda amb diversos requeriments de qualitat de servei (QoS). El desenvolupament de la multiplexació per divisió de longitud d’ona (WDM) en els anys noranta va fer molt rendible la disponibilitat d’ample de banda. Avui dia, les tecnologies de commutació òptica de circuits són predominants en el nucli de la xarxa, les quals permeten la configuració de canals (lightpaths) a través de la xarxa. No obstant això, la granularitat d’aquests canals ocupa tota la longitud d’ona, el que fa que siguin ineficients per a proveir canals de menor ample de banda (sub-longitud d’ona). Segons la comunitat científica, és necessari augmentar la transparència dels protocols, així com millorar l’aprovisionament d’ample de banda de forma dinàmica. Per tal de fer això realitat, és necessari desenvolupar noves arquitectures. La commutació òptica de ràfegues i de paquets (OBS/OPS), són dues de les tecnologies proposades. Aquesta tesi contribueix amb tres arquitectures de xarxa destinades a millorar el transport de dades sub-longitud d’ona. En primer lloc, aprofundim en la naturalesa sense connexió en OBS. En aquest cas, la xarxa incrementa el seu dinamisme a causa de les transmissions a ràfega. A més, les col·lisions entre ràfegues degraden el rendiment de la xarxa fins i tot a càrregues molt baixes. Per fer front a aquestes col·lisions, es proposa un esquema de resolució de col·lisions pro actiu basat en un algorisme d’encaminament i assignació de longitud d’ona (RWA) que balanceja de forma automàtica i distribuïda la càrrega en la xarxa. En aquest protocol, el RWA i la transmissió de ràfegues es basen en l’explotació i exploració de regles de commutació que incorporen informació sobre contencions i encaminament. Per donar suport a aquesta arquitectura, s’utilitzen dos tipus de paquets de control per a l’encaminament de les ràfegues i l’actualització de les regles de commutació, respectivament. Per analitzar els beneficis del nou algorisme, s’utilitzen quatre topologies de xarxa diferents. Els resultats indiquen que el mètode proposat millora en diferents marges la resta d’algorismes RWA en funció de la topologia i sense penalitzar altres paràmetres com el retard extrem a extrem. La segona contribució proposa una arquitectura híbrida sense i orientada a connexió sobre la base d’un protocol de control d’accés al medi (MAC) per a xarxes OBS (DAOBS). El MAC ofereix dos mètodes d’accés: arbitratge de cua (QA) per a la transmissió de ràfegues sense connexió, i pre-arbitratge (PA) per serveis TDM orientats a connexió. Aquesta arquitectura permet una àmplia gamma d’aplicacions sensibles al retard i al bloqueig. Els resultats avaluats a través de simulacions mostren que en l’accés QA, les ràfegues de més alta prioritat tenen garantides zero pèrdues i latències d’accés molt baixes. Pel que fa a l’accés PA, es reporta que la duplicació de la càrrega TDM augmenta en més d’un ordre la probabilitat de bloqueig, però sense afectar en la mateixa mesura les ràfegues sense connexió. En aquest capítol també es tracten dos dels problemes relacionats amb l’arquitectura DAOBS i el seu funcionament. En primer lloc, es proposa un model matemàtic per aproximar el retard d’accés inferior i superior com a conseqüència de l’accés QA. En segon lloc, es formula matemàticament la generació i optimització de les topologies virtuals que suporten el protocol per a l’escenari amb tràfic estàtic. Finalment, l’última contribució explora els beneficis d’una arquitectura de xarxa òptica per temps compartit (TSON) basada en elements de càlcul de camins (PCE) centralitzats per tal d’evitar col·lisions en la xarxa. Aquesta arquitectura permet garantir l’aprovisionament orientat a connexió de canals sub-longitud d’ona. En aquest capítol proposem i simulem tres arquitectures GMPLS/PCE/TSON. A causa del enfocament centralitzat, el rendiment de la xarxa depèn en gran mesura de l’assignació i aprovisionament de les connexions. Amb aquesta finalitat, es proposen diferents algorismes d’assignació de ranures temporals i es comparen amb les corresponents formulacions de programació lineal (ILP) per al cas estàtic. Per al cas de tràfic dinàmic, proposem i avaluem mitjançant simulació diferents heurístiques. Els resultats mostren els beneficis de proporcionar flexibilitat en els dominis temporal i freqüencial a l’hora d’assignar les ranures temporals.The rapid evolving Internet and the broad range of new data applications (e.g., multimedia, video-conference, online gaming, etc.) is fostering revolutionary changes in the way we communicate. In addition, some of these applications demand for unprecedented amounts of bandwidth resources with diverse quality of service (QoS). The development of wavelength division multiplexing (WDM) in the 90's made very cost-effective the availability of bandwidth. Nowadays, optical circuit switching technologies are predominant in the core enabling the set up of lightpaths across the network. However, full-wavelength lightpath granularity is too coarse, which results to be inefficient for provisioning sub-wavelength channels. As remarked by the research community, an open issue in optical networking is increasing the protocol transparency as well as provisioning true dynamic bandwidth allocation at the network level. To this end, new architectures are required. Optical burst/packet switching (OBS/OPS) are two such proposed technologies under investigation. This thesis contributes with three network architectures which aim at improving the sub-wavelength data transport from different perspectives. First, we gain insight into the connectionless nature of OBS. Here, the network dynamics are increased due to the short-lived burst transmissions. Moreover, burst contentions degrade the performance even at very low loads. To cope with them, we propose a proactive resolution scheme by means of a distributed auto load-balancing routing and wavelength assignment (RWA) algorithm for wavelength-continuity constraint networks. In this protocol, the RWA and burst forwarding is based on the exploitation and exploration of switching rule concentration values that incorporate contention and forwarding desirability information. To support such architecture, forward and backward control packets are used in the burst forwarding and updating rules, respectively. In order to analyze the benefits of the new algorithm, four different network topologies are used. Results indicate that the proposed method outperforms the rest of tested RWA algorithms at various margins depending on the topology without penalizing other parameters such as end-to-end delay. The second contribution proposes a hybrid connectionless and connection-oriented architecture based on a medium access control (MAC) protocol for OBS networks (DAOBS). The MAC provides two main access mechanisms: queue arbitrated (QA) for connectionless bursts and pre-arbitrated (PA) for TDM connection-oriented services. Such an architecture allows for a broad range of delay-sensitive applications or guaranteed services. Results evaluated through simulations show that in the QA access mode highest priority bursts are guaranteed zero losses and very low access latencies. Regarding the PA mode, we report that doubling the offered TDM traffic load increases in more than one order their connection blocking, slightly affecting the blocking of other connectionless bursts. In this chapter, we also tackle two of the issues related with the DAOBS architecture and its operation. Firstly, we model mathematically the lower and upper approximations of the access delay as a consequence of the connectionless queue arbitrated access. Secondly, we formulate the generation of the virtual light-tree overlay topology for the static traffic case.Postprint (published version

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

Optimal Control of SOAs With Artificial Intelligence for Sub-Nanosecond Optical Switching

Novel approaches to switching ultra-fast semiconductor optical amplifiers using artificial intelligence algorithms (particle swarm optimisation, ant colony optimisation, and a genetic algorithm) are developed and applied both in simulation and experiment. Effective off-on switching (settling) times of 542 ps are demonstrated with just 4.8% overshoot, achieving an order of magnitude improvement over previous attempts described in the literature and standard dampening techniques from control theory

Ant colony optimisation-based algorithms for optical burst switching networks

This research developed two novel distributed algorithms inspired by Ant Colony Optimisation (ACO) for a solution to the problem of dynamic Routing and Wavelength Assignment (RWA) with wavelength continuity constraint in Optical Burst Switching (OBS) networks utilising both the traditional International Telecommunication Union (ITU) Fixed Grid Wavelength Division Multiplexing (WDM) and Flexible Spectrum scenarios. The growing demand for more bandwidth in optical networks require more efficient utilisation of available optical resources. OBS is a promising optical switching technique for the improved utilisation of optical network resources over the current optical circuit switching technique. The development of newer technologies has introduced higher rate transmissions and various modulation formats, however, introducing these technologies into the traditional ITU Fixed Grid does not efficiently utilise the available bandwidth. Flexible Spectrum is a promising approach offering a solution to the problem of improving bandwidth utilisation, which comes with a potential cost. Transmissions have the potential for impairment with respect to the increased traffic and lack of large channel spacing. Proposed routing algorithms should be aware of the linear and non-linear Physical Layer Impairments (PLIs) in order to operate closer to optimum performance. The OBS resource reservation protocol does not cater for the loss of transmissions, Burst Control Packets (BCPs) included, due to physical layer impairments. The protocol was adapted for use in Flexible Spectrum. Investigation of the use of a route and wavelength combination, from source to destination node pair, for the RWA process was proposed for ACO-based approaches to enforce the establishment and use of complete paths for greedy exploitation in Flexible Spectrum was conducted. The routing tuple for the RWA process is the tight coupling of a route and wavelength in combination intended to promote the greedy exploitation of successful paths for transmission requests. The application of the routing tuples differs from traditional ACO-based approaches and prompted the investigation of new pheromone calculation equations. The two novel proposed approaches were tested and experiments conducted comparing with and against existing algorithms (a simple greedy and an ACO-based algorithm) in a traditional ITU Fixed Grid and Flexible Spectrum scenario on three different network topologies. The proposed Flexible Spectrum Ant Colony (FSAC) approach had a markably improved performance over the existing algorithms in the ITU Fixed Grid WDM and Flexible Spectrum scenarios, while Upper Confidence Bound Routing and Wavelength Assignment (UCBRWA) algorithm was able to perform well in the traditional ITU Fixed Grid WDM scenario, but underperformed in the Flexible Spectrum scenario. The results show that the distributed ACO-based FSAC algorithm significantly improved the burst transmission success probability, providing a good solution in the Flexible Spectrum network environment undergoing transmission impairments

Joint dimensioning of server and network infrastructure for resilient optical grids/clouds

We address the dimensioning of infrastructure, comprising both network and server resources, for large-scale decentralized distributed systems such as grids or clouds. We design the resulting grid/cloud to be resilient against network link or server failures. To this end, we exploit relocation: Under failure conditions, a grid job or cloud virtual machine may be served at an alternate destination (i.e., different from the one under failure-free conditions). We thus consider grid/cloud requests to have a known origin, but assume a degree of freedom as to where they end up being served, which is the case for grid applications of the bag-of-tasks (BoT) type or hosted virtual machines in the cloud case. We present a generic methodology based on integer linear programming (ILP) that: 1) chooses a given number of sites in a given network topology where to install server infrastructure; and 2) determines the amount of both network and server capacity to cater for both the failure-free scenario and failures of links or nodes. For the latter, we consider either failure-independent (FID) or failure-dependent (FD) recovery. Case studies on European-scale networks show that relocation allows considerable reduction of the total amount of network and server resources, especially in sparse topologies and for higher numbers of server sites. Adopting a failure-dependent backup routing strategy does lead to lower resource dimensions, but only when we adopt relocation (especially for a high number of server sites): Without exploiting relocation, potential savings of FD versus FID are not meaningful