33 research outputs found
Management of Spectral Resources in Elastic Optical Networks
Recent developments in the area of mobile technologies, data center networks, cloud computing and social networks have triggered the growth of a wide range of network applications. The data rate of these applications also vary from a few megabits per second (Mbps) to several Gigabits per second (Gbps), thereby increasing the burden on the Inter- net. To support this growth in Internet data traffic, one foremost solution is to utilize the advancements in optical networks. With technology such as wavelength division multiplexing (WDM) networks, bandwidth upto 100 Gbps can be exploited from the optical fiber in an energy efficient manner. However, WDM networks are not efficient when the traffic demands vary frequently. Elastic Optical Networks (EONs) or Spectrum Sliced Elastic Optical Path Networks (SLICE) or Flex-Grid has been recently proposed as a long-term solution to handle the ever-increasing data traffic and the diverse demand range. EONs provide abundant bandwidth by managing the spectrum resources as fine-granular orthogonal sub-carriers that makes it suitable to accommodate varying traffic demands. However, the Routing and Spectrum Allocation (RSA) algorithm in EONs has to follow additional constraints while allocating sub-carriers to demands. These constraints increase the complexity of RSA in EONs and also, make EONs prone to the fragmentation of spectral resources, thereby decreasing the spectral efficiency. The major objective of this dissertation is to study the problem of spectrum allocation in EONs under various network conditions. With this objective, this dissertation presents the author\u27s study and research on multiple aspects of spectrum allocation in EONs: how to allocate sub-carriers to the traffic demands, how to accommodate traffic demands that varies with time, how to minimize the fragmentation of spectral resources and how to efficiently integrate the predictability of user demands for spectrum assignment. Another important contribution of this dissertation is the application of EONs as one of the substrate technologies for network virtualization
Acta Universitatis Sapientiae - Electrical and Mechanical Engineering
Series Electrical and Mechanical Engineering publishes original papers and surveys in various fields of Electrical and Mechanical Engineering
Software Defined Applications in Cellular and Optical Networks
abstract: Small wireless cells have the potential to overcome bottlenecks in wireless access through the sharing of spectrum resources. A novel access backhaul network architecture based on a Smart Gateway (Sm-GW) between the small cell base stations, e.g., LTE eNBs, and the conventional backhaul gateways, e.g., LTE Servicing/Packet Gateways (S/P-GWs) has been introduced to address the bottleneck. The Sm-GW flexibly schedules uplink transmissions for the eNBs. Based on software defined networking (SDN) a management mechanism that allows multiple operator to flexibly inter-operate via multiple Sm-GWs with a multitude of small cells has been proposed. This dissertation also comprehensively survey the studies that examine the SDN paradigm in optical networks. Along with the PHY functional split improvements, the performance of Distributed Converged Cable Access Platform (DCCAP) in the cable architectures especially for the Remote-PHY and Remote-MACPHY nodes has been evaluated. In the PHY functional split, in addition to the re-use of infrastructure with a common FFT module for multiple technologies, a novel cross functional split interaction to cache the repetitive QAM symbols across time at the remote node to reduce the transmission rate requirement of the fronthaul link has been proposed.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201
Towards cognitive in-operation network planning
Next-generation internet services such as live TV and video on demand require high bandwidth and ultra-low latency. The ever-increasing volume, dynamicity and stringent requirements of these services’ demands are generating new challenges to nowadays telecom networks. To decrease expenses, service-layer content providers are delivering their content near the end users, thus allowing a low latency and tailored content delivery. As a consequence of this, unseen metro and even core traffic dynamicity is arising with changes in the volume and direction of the traffic along the day.
A tremendous effort to efficiently manage networks is currently ongoing towards the realisation of 5G networks. This translates in looking for network architectures supporting dynamic resource allocation, fulfilling strict service requirements and minimising the total cost of ownership (TCO). In this regard, in-operation network planning was recently proven to successfully support various network reconfiguration use cases in prospective scenarios. Nevertheless, additional research to extend in-operation planning capabilities from typical reactive optimization schemes to proactive and predictive schemes based on the analysis of network monitoring data is required.
A hot topic raising increasing attention is cognitive networking, where an elevated knowledge about the network could be obtained as a result of introducing data analytics in the telecom operator’s infrastructure. By using predictive knowledge about the network traffic, in-operation network planning mechanisms could be enhanced to efficiently adapt the network by means of future traffic prediction, thus achieving cognitive in-operation network planning.
In this thesis, we focus on studying mechanisms to enable cognitive in-operation network planning in core networks. In particular, we focus on dynamically reconfiguring virtual network topologies (VNT) at the MPLS layer, covering a number of detailed objectives. First, we start studying mechanisms to allow network traffic flow modelling, from monitoring and data transformation to the estimation of predictive traffic model based on this data. By means of these traffic models, then we tackle a cognitive approach to periodically adapt the core VNT to current and future traffic, using predicted traffic matrices based on origin-destination (OD) predictive models. This optimization approach, named VENTURE, is efficiently solved using dedicated heuristic algorithms and its feasibility is demonstrated in an experimental in-operation network planning environment. Finally, we extend VENTURE to consider core flows dynamicity as a result of metro flows re-routing, which represents a meaningful dynamic traffic scenario. This extension, which entails enhancements to coordinate metro and core network controllers with the aim of allowing fast adaption of core OD traffic models, is evaluated and validated in terms of traffic models accuracy and experimental feasibility.Els serveis d’internet de nova generaciĂł tals com la televisiĂł en viu o el vĂdeo sota demanda requereixen d’un gran ample de banda i d’ultra-baixa latència. L’increment continu del volum, dinamicitat i requeriments d’aquests serveis estĂ generant nous reptes pels teleoperadors de xarxa. Per reduir costs, els proveĂŻdors de contingut estan disposant aquests mĂ©s a prop dels usuaris finals, aconseguint aixĂ una entrega de contingut feta a mida. ConseqĂĽentment, estem presenciant una dinamicitat mai vista en el trĂ fic de xarxes de metro amb canvis en la direcciĂł i el volum del trĂ fic al llarg del dia. Actualment, s’estĂ duent a terme un gran esforç cap a la realitzaciĂł de xarxes 5G. Aquest esforç es tradueix en cercar noves arquitectures de xarxa que suportin l’assignaciĂł dinĂ mica de recursos, complint requeriments de servei estrictes i minimitzant el cost total de la propietat. En aquest sentit, recentment s’ha demostrat com l’aplicaciĂł de “in-operation network planning” permet exitosament suportar diversos casos d’ús de reconfiguraciĂł de xarxa en escenaris prospectius. No obstant, Ă©s necessari dur a terme mĂ©s recerca per tal d’estendre “in-operation network planning” des d’un esquema reactiu d’optimitzaciĂł cap a un nou esquema proactiu basat en l’analĂtica de dades provinents del monitoritzat de la xarxa. El concepte de xarxes cognitives es tambĂ© troba al centre d’atenciĂł, on un elevat coneixement de la xarxa s’obtindria com a resultat d’introduir analĂtica de dades en la infraestructura del teleoperador. Mitjançant un coneixement predictiu sobre el trĂ fic de xarxa, els mecanismes de in-operation network planning es podrien millorar per adaptar la xarxa eficientment basant-se en predicciĂł de trĂ fic, assolint aixĂ el que anomenem com a “cognitive in-operation network Planning”. En aquesta tesi ens centrem en l’estudi de mecanismes que permetin establir “el cognitive in-operation network Planning” en xarxes de core. En particular, ens centrem en reconfigurar dinĂ micament topologies de xarxa virtual (VNT) a la capa MPLS, cobrint una sèrie d’objectius detallats. Primer comencem estudiant mecanismes pel modelat de fluxos de trĂ fic de xarxa, des del seu monitoritzat i transformaciĂł fins a l’estimaciĂł de models predictius de trĂ fic. Posteriorment, i mitjançant aquests models predictius, tractem un esquema cognitiu per adaptar periòdicament la VNT utilitzant matrius de trĂ fic basades en predicciĂł de parells origen-destĂ (OD). Aquesta optimitzaciĂł, anomenada VENTURE, Ă©s resolta eficientment fent servir heurĂstiques dedicades i Ă©s posteriorment avaluada sota escenaris de trĂ fic de xarxa dinĂ mics. A continuaciĂł, estenem VENTURE considerant la dinamicitat dels fluxos de trĂ fic de xarxes de metro, el qual representa un escenari rellevant de dinamicitat de trĂ fic. Aquesta extensiĂł involucra millores per coordinar els operadors de metro i core amb l’objectiu d’aconseguir una rĂ pida adaptaciĂł de models de trĂ fic OD. Finalment, proposem dues arquitectures de xarxa necessĂ ries per aplicar els mecanismes anteriors en entorns experimentals, emprant protocols estat-de-l’art com sĂłn OpenFlow i IPFIX. La metodologia emprada per avaluar el treball anterior consisteix en una primera avaluaciĂł numèrica fent servir un simulador de xarxes Ăntegrament dissenyat i desenvolupat per a aquesta tesi. DesprĂ©s d’aquesta validaciĂł basada en simulaciĂł, la factibilitat experimental de les arquitectures de xarxa proposades Ă©s avaluada en un entorn de proves distribuĂŻt