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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Analyse de performance des réseaux optiques à commutation en sous-longueur d'onde / Performance analysis of subwavelength switching optical networks

Indre, Raluca Maria 05 November 2012 (has links)
Un défi majeur dans les réseaux d’aujourd’hui est de combler l’écart entre la haute vitesse de la transmission optique et la vitesse plus limitée du traitement électronique des données. Une option est de commuter les données directement dansle domaine optique. Dans cette thèse, nous proposons plusieurs solutions permettant la commutation dans le domaine optique à une granularité plus fine que la longueur d’onde, technique que nous appelons commutation sous-longueurd’onde. Pour montrer la pertinence des solutions proposées, nous analysons leur performance en termes de capacité de trafic, de débit et de délai. La performance est évaluée à la fois par des simulations et en utilisant des modèles de filesd’attente appropriés. Nous considérons d’abord le cas des réseaux métropolitains (Metropolitan Area Networks, MAN) et nous étudions la performance d’un anneau optique avec multiplexage en longueur d’onde (Wavelength Division Multiplexing, WDM) dans lequel la communication entre les noeuds du réseau se fait par insertion/extraction de données dans des créneaux temporels. Nous présentons un protocole entièrement distribué conçu pour assurer l’équité dansce réseau. Nous proposons également un mécanisme d’assemblage de paquets capable d’assurer des délais faibles ainsi que des taux de remplissage élevés. Nous proposons ensuite des solutions de commutation sous-longueur d’onde qui peuvent être appliquées dans le cas plus général des réseaux asynchrones. D’abord, nous proposons de résoudre le problème des collisions de la commutation optique par rafale (Optical Burst Switching, OBS) par la mise en oeuvre d’un mécanisme de réservation. Afin de maximiser l’utilisation des ressources, nous proposons d’adapter la taille de la rafale optique à la charge du réseau.Ensuite, nous proposons une solution alternative pour construire un réseau coeur tout-optique. A cette architecture, nous associons un protocole d’accès ainsi qu’un algorithme d’allocation dynamique de bande passante et nous analysons les performances de la solution proposée. Par le biais d’une étude de cas, nousmontrons que notre solution est capable de réduire considérablement la consommation énergétique par rapport aux architectures actuelles basées sur des routeurs IP. Enfin, nous proposons un nouveau dispositif optique capable derésoudre la contention directement dans le domaine optique. Nous montrons que ce dispositif simple peut être utilisé pour construire des réseaux optiques dynamiques à courte portée tels que les réseaux d’accès ou les centres de traitement de données. / A key challenge in today’s networks is to bridge the gap between high-speed optical transmission and limited electronic processing. This can be achieved by enabling payload to be switched directly in the optical domain.A simple solutionto provide optical switching is by allocating one wavelength channel to each source-destination pair, a technique called Optical Circuit Switching (OCS). Due to lack of sharing, OCS suffers from limited scalability. To overcome this issue,the capacity of each wavelength channel must be dynamically shared among different source-destination pairs. This requires data to be switched at subwavelength granularity by means of subwavelength switching. In this thesis, wepropose several solutions which enable subwavelength switching in optical networks. To show the relevance of the proposed solutions, we analyse their performance in terms of traffic capacity, flow throughput and packet delay. Performance is evaluated both through simulations and by means of appropriate queueing models. We first consider the case of Metropolitan Area Networks (MAN) and we study the performance of synchronous time-slotted Wavelength DivisionMultiplexing (WDM) ring in which network nodes communicate by inserting and extracting data from time-slots. We present a fully distributedMedia Access Control (MAC) protocol designed to ensure fairness. We also propose a burst assembly mechanism able to ensure low assembly delays and high fill rates of the optical time-slots. We then propose subwavelength switching solutions which can be applied in the more general case of asynchronous wide area networks. We first propose to solve the contention problems of conventional Optical Burst Switching (OBS) and the low utilization issue of wavelength-routed OBS byimplementing a two-way reservation OBS scheme in which the size of the opticalburst increases proportionally with the network load so as to maximize resourceutilization. Next, we propose a solution for building an all-optical wide area network based on multipoint-to-multipoint lightpath sharing. We also design an associated MAC protocol and a dynamic bandwidth allocation algorithm and analyse the performance of the proposed solution. By means of a case study, we show that the proposed solution has the potential to considerably reduce power consumption with respect to current router-based architectures. Finally, we propose a novel optical device able to solve contention directly in the optical domain withoutrequiring any optical buffering, electronic signalling or header processing. We show that thissimple device can be used as a building block for dynamic and power efficient short-range optical networks such as access networks or data centers.
32

Traffic and performance evaluation for optical networks. An Investigation into Modelling and Characterisation of Traffic Flows and Performance Analysis and Engineering for Optical Network Architectures.

Mouchos, Charalampos January 2009 (has links)
The convergence of multiservice heterogeneous networks and ever increasing Internet applications, like peer to peer networking and the increased number of users and services, demand a more efficient bandwidth allocation in optical networks. In this context, new architectures and protocols are needed in conjuction with cost effective quantitative methodologies in order to provide an insight into the performance aspects of the next and future generation Internets. This thesis reports an investigation, based on efficient simulation methodologies, in order to assess existing high performance algorithms and to propose new ones. The analysis of the traffic characteristics of an OC-192 link (9953.28 Mbps) is initially conducted, a requirement due to the discovery of self-similar long-range dependent properties in network traffic, and the suitability of the GE distribution for modelling interarrival times of bursty traffic in short time scales is presented. Consequently, using a heuristic approach, the self-similar properties of the GE/G/¿ are being presented, providing a method to generate self-similar traffic that takes into consideration burstiness in small time scales. A description of the state of the art in optical networking providing a deeper insight into the current technologies, protocols and architectures in the field, which creates the motivation for more research into the promising switching technique of ¿Optical Burst Switching¿ (OBS). An investigation into the performance impact of various burst assembly strategies on an OBS edge node¿s mean buffer length is conducted. Realistic traffic characteristics are considered based on the analysis of the OC-192 backbone traffic traces. In addition the effect of burstiness in the small time scales on mean assembly time and burst size distribution is investigated. A new Dynamic OBS Offset Allocation Protocol is devised and favourable comparisons are carried out between the proposed OBS protocol and the Just Enough Time (JET) protocol, in terms of mean queue length, blocking and throughput. Finally the research focuses on simulation methodologies employed throughout the thesis using the Graphics Processing Unit (GPU) on a commercial NVidia GeForce 8800 GTX, which was initially designed for gaming computers. Parallel generators of Optical Bursts are implemented and simulated in ¿Compute Unified Device Architecture¿ (CUDA) and compared with simulations run on general-purpose CPU proving the GPU to be a cost-effective platform which can significantly speed-up calculations in order to make simulations of more complex and demanding networks easier to develop.
33

IMPROVING LIGHTPATH ESTABLISHMENT IN ELASTIC OPTICAL NETWORKS

Al Baidhani, Amer Hashim Mohammed 01 August 2017 (has links)
No description available.
34

Injection-Locked Fabry-Perot Laser Diode In Wavelength Division Multiplexing Passive Optical Network

Yan, Yudan 07 1900 (has links)
The bandwidth demanding in the access network has been increasing rapidly over the past several years. The predominant broadband access network solutions deployed today are digital subscriber line (DSL) and community antenna television (CATV) (cable TV) based networks. However, the passive optical network (PON) which is a point to multipoint access network based on optical fibers provides much higher bandwidth compared to current access networks based on copper lines. Incorporating wavelength division multiplexing (WDM) in a PON allows a much higher bandwidth compared to the standard PON which operates in the single wavelength mode where the one wavelength is used for upstream transmission and another different wavelength is used for downstream transmission. Moreover, WDM-PON offers the advantages in terms of capacity, low latency and service transparency. In the past five years WDM-PON technology has been developed to a mature for commercial consideration. In this thesis, we start from some fundamentals about WDM-PON and the technology challenge for WDM-PON which is to avoid the need for expensive wavelength selective optical components in the end-user optical network unit (ONU). Then we investigate Injection Locked Fabry-Perot Laser Diode with narrow band amplified spontaneous emission (ASE) noise as an approach to be a wavelength independent ONU. We study its theoretical model and compare the experimental results with the simulation results based on the theoretical model. / Thesis / Candidate in Philosophy
35

Dynamic bandwidth allocation MAC protocols for gigabit-capable passive optical networks

Chang, Ching-Hung January 2008 (has links)
The research initiatives addressed in this thesis are geared towards improving the performance of passive optical networks (PONs) through the development of advanced dynamic bandwidth allocation (DBA) protocols. In particular, the aim of the research undertaken is to enhance the quality of service (QoS) offered by standard PONs by means of providing subscribers with service level agreement (SLA) to fulfil applications and associated bandwidth requirements on demand. To accomplish the research objectives, a novel service and bandwidth focused DBA protocol is developed for standard time division multiplexing (TDM), gigabit-capable PONs (GPONs) by flexibly assigning a guaranteed minimum bandwidth to each optical network unit (ONU),terminated at subscribers premises. Modelling and simulation of the developed algorithms have displayed a tenfold enhancement in network performance, showing a superior performance to other published DBA protocols, in terms of mean packet delay. To accomplish protocol optimisation, the ONU upstream transmission properties of TDM-PONs have been further analysed and subsequently the ONU data transfer order in each communication cycle has been dynamically configured to increase the network upstream throughput by overlapping the upstream transmission period with parts of the bandwidth request-allocation process between OLT and ONUs. In addition, with the objective of extending the application of the developed protocol to long-reach PONs by means of reducing the augmented propagation delays due to the network’s extensive reach, the concept of virtual communication cycles has been incorporated into the optimised DBA algorithm. This approach demonstrates comparable transmission efficiency in the context of subscriber throughput and packet delay as in a standard PON but at much longer distances from the network exchange. To overcome the inevitably limited communication capacity of single wavelength TDM protocols and with the transportation of the ever increasing, time-sensitive, multi-media services in mind, a novel multi-wavelength DBA protocol is then developed to be applied to a wavelength division multiplexing–PON. With this protocol, both the downstream and upstream network capacity is dynamically adjusted according to subscribers’ service level and bandwidth demand in each polling cycle as opposed to a fixed upstream network capacity in TDM-PONs. It therefore also demonstrates improved upstream transmission efficiency.
36

Algoritmos para alocação de banda em redes de acesso GPON / Algorithms for bandwidth allocation in GPON access networks

Santos, Alex Ferreira dos 26 February 2010 (has links)
Neste trabalho propomos e analisamos algoritmos de alocação dinâmica de banda para rede óptica passiva (PON) de acesso padrão GPON (Gigabit PON). Estes algoritmos utilizam dados oriundos de SLA (service level agreement) para gerenciar a alocação de banda e classificar em 4 contêineres de tráfego (T-CONT) o tráfego gerado em 16 ONUs (optical network unit). Na transmissão upstream é utilizada a técnica de multiplexação por divisão de tempo (TDM) para gerenciar o acesso ao meio, evitando colisões. O primeiro algoritmo proposto aloca banda garantida para as ONUs e distribui a banda não utilizada de acordo com critério baseado em três SLAs. A taxa de bit upstream é 1,25 Gbps e o desempenho do algoritmo é analisado com base na variação do atraso de pacotes em função do tráfego gerado nas ONUs. O segundo algoritmo proposto utiliza ponderação de tráfego. Neste, analisamos o comportamento dos atrasos e a quantidade de banda solicitada e atendida por ONU quando as bandas garantida e extra são alteradas. Por fim, acrescentamos em nossa implementação um intervalo para o processamento do algoritmo de alocação dinâmica de banda (DBA) e resposta do hardware relacionado ao ciclo de interrogação. Então, analisamos o atraso de pacotes quando variamos o intervalo de processamento do DBA. Ao final, propomos uma solução preliminar para minimizar estes atrasos. Os resultados obtidos por meio de simulação computacional mostram a versatilidade dos algoritmos. / In this work we propose and analyze the performance of dynamic bandwidth allocation algorithms for optical passive networks (PON) in GPON standard (Gigabit PON). These algorithms use data from SLA (service level agreement) to manage bandwidth allocation and classify in 4 traffic containers (T-CONT) the traffic generated by 16 ONUs (optical network unit). In the upstream transmission the time division multiplexing (TDM) technique is used to manage the medium access, avoiding collisions. The first proposed algorithm allocates guaranteed bandwidth for the ONUs and distributes the bandwidth not used according to the criteria based on three SLAs. The upstream bit rate is 1.25 Gbps and the algorithm performance is analyzed based on the packets delay variation versus the traffic generated by ONUs. The second proposed algorithm uses weighted traffic. In this, we analyze the delay performance and the required bandwidth for each ONU and how much it is served when the guaranteed and extra bandwidth are changed. Finally, we added in our implementation an interval for the processing of the dynamic bandwidth allocation algorithm (DBA) and response of the hardware related to the interrogation cycle. In the end, we propose a preliminary solution to minimize these delays. The results obtained by means of computational simulation show the versatility of the algorithms.
37

Algoritmos para alocação de banda em redes de acesso GPON / Algorithms for bandwidth allocation in GPON access networks

Alex Ferreira dos Santos 26 February 2010 (has links)
Neste trabalho propomos e analisamos algoritmos de alocação dinâmica de banda para rede óptica passiva (PON) de acesso padrão GPON (Gigabit PON). Estes algoritmos utilizam dados oriundos de SLA (service level agreement) para gerenciar a alocação de banda e classificar em 4 contêineres de tráfego (T-CONT) o tráfego gerado em 16 ONUs (optical network unit). Na transmissão upstream é utilizada a técnica de multiplexação por divisão de tempo (TDM) para gerenciar o acesso ao meio, evitando colisões. O primeiro algoritmo proposto aloca banda garantida para as ONUs e distribui a banda não utilizada de acordo com critério baseado em três SLAs. A taxa de bit upstream é 1,25 Gbps e o desempenho do algoritmo é analisado com base na variação do atraso de pacotes em função do tráfego gerado nas ONUs. O segundo algoritmo proposto utiliza ponderação de tráfego. Neste, analisamos o comportamento dos atrasos e a quantidade de banda solicitada e atendida por ONU quando as bandas garantida e extra são alteradas. Por fim, acrescentamos em nossa implementação um intervalo para o processamento do algoritmo de alocação dinâmica de banda (DBA) e resposta do hardware relacionado ao ciclo de interrogação. Então, analisamos o atraso de pacotes quando variamos o intervalo de processamento do DBA. Ao final, propomos uma solução preliminar para minimizar estes atrasos. Os resultados obtidos por meio de simulação computacional mostram a versatilidade dos algoritmos. / In this work we propose and analyze the performance of dynamic bandwidth allocation algorithms for optical passive networks (PON) in GPON standard (Gigabit PON). These algorithms use data from SLA (service level agreement) to manage bandwidth allocation and classify in 4 traffic containers (T-CONT) the traffic generated by 16 ONUs (optical network unit). In the upstream transmission the time division multiplexing (TDM) technique is used to manage the medium access, avoiding collisions. The first proposed algorithm allocates guaranteed bandwidth for the ONUs and distributes the bandwidth not used according to the criteria based on three SLAs. The upstream bit rate is 1.25 Gbps and the algorithm performance is analyzed based on the packets delay variation versus the traffic generated by ONUs. The second proposed algorithm uses weighted traffic. In this, we analyze the delay performance and the required bandwidth for each ONU and how much it is served when the guaranteed and extra bandwidth are changed. Finally, we added in our implementation an interval for the processing of the dynamic bandwidth allocation algorithm (DBA) and response of the hardware related to the interrogation cycle. In the end, we propose a preliminary solution to minimize these delays. The results obtained by means of computational simulation show the versatility of the algorithms.
38

Architectural exploration of network Interface for energy efficient 3D optical network-on-chip / Exploration architecturale d'un système 3D multi-coeurs communiquant par réseau optique embarqué sur puce

Pham, Van Dung 13 December 2018 (has links)
Depuis quelques années, les réseaux optiques sur puce (ONoC) sont devenus une solution intéressante pour surpasser les limitations des interconnexions électriques, compte tenu de leurs caractéristiques attractives concernant la consommation d’énergie, le délai de transfert et la bande passante. Cependant, les éléments optiques nécessaires pour définir un tel réseau souffrent d’imperfections qui introduisent des pertes durant les communications. De plus, l'utilisation de la technique de multiplexage en longueurs d'ondes (WDM) permet d'augmenter les performances, mais introduit de nouvelles pertes et de la diaphonie entre les longueurs d'ondes, ce qui a pour effet de réduire le rapport signal sur bruit et donc la qualité de la communication. Les contributions présentées dans ce manuscrit adressent cette problématique d’amélioration de performance des liens optiques dans un ONoC. Pour cela, nous proposons tout d’abord un modèle analytique des pertes et de la diaphonie dans un réseau optique sur puce WDM. Nous proposons ensuite une méthodologie pour améliorer les performances globales du système s'appuyant sur l'utilisation de codes correcteurs d'erreurs. Nous présentons deux types de codes, le premier(Hamming) est d'une complexité d'implémentation faible alors que le second(Reed-Solomon) est plus complexe, mais offre un meilleur taux de correction. Nous avons implémenté des blocs matériels supportant ces corrections d'erreurs avec une technologie 28nm FDSOI. Finalement, nous proposons la définition d'une interface complète entre le domaine électrique et le domaine optique permettant d'allouer les longueurs d'ondes, de coder l'information, de sérialiser le flux de données et de contrôler le driver du laser pour obtenir la modulation à la puissance optique souhaitée. / Electrical Network-on-Chip (ENoC) has long been considered as the de facto technology for interconnects in multiprocessor systems-on-chip (MPSoCs). However, with the increase of the number of cores integrated on a single chip, ENoCs are less and less suitable to adapt the bandwidth and latency requirements of nowadays complex and highly-parallel applications. In recent years, due to power consumption constraint, low latency, and high data bandwidth requirements, optical interconnects became an interesting solution to overcome these limitations. Indeed, Optical Networks on Chip (ONoC) are based on waveguides which drive optical signals  from source to destination with very low latency. Unfortunately, the optical devices used to built  ONoCs suffer from some imperfections which introduce losses during communications. These losses (crosstalk noises and optical losses)  are very important factors which impact the energy efficiency and the performance of the system. Furthermore, Wavelength Division Multiplexing (WDM) technology can help the designer to improve ONoC performance, especially the bandwidth and the latency. However, using the WDM technology leads to introduce new losses and crosstalk noises which negatively impact the Signal to Noise Ratio (SNR) and Bit Error Rate (BER). In detail, this results in higher BER and increases power consumption, which therefore reduces the energy efficiency of the optical interconnects. The contributions presented in this manuscript address these issues. For that, we first model and analyze the optical losses and crosstalk in WDM based ONoC. The model can provide an analytical evaluation of the worst case of loss and crosstalk with different parameters for optical ring network-on-chip. Based on this model, we propose a methodology to improve the performance and then to reduce the power consumption of optical interconnects relying on the use of forward error correction (FEC). We present two case studies of lightweight FEC with low implementation complexity and high error-correction performance under 28nm Fully-Depleted Silicon-On-Insulator (FDSOI) technology. The results demonstrate the advantages of using FEC on the optical interconnect in the context of the CHAMELEON ONoC. Secondly, we propose a complete design of Optical Network Interface (ONI) which is composed of data flow allocation, integrated FECs, data serialization/deserialization, and control of the laser driver. The details of these different elements are presented in this manuscript.  Relying on this network interface, an allocation management to improve energy efficiency can be supported at runtime depending on the application demands. This runtime management of energy vs. performance can be integrated into the ONI manager through configuration manager located in each ONI. Finally, the design of an ONoC configuration sequencer (OCS), located at the center of the optical layer, is presented. By using the ONI manager, the OCS can configure ONoC at runtime according to the application performance and energy requirements.
39

Trendy přístupových sítí / Trends in Access Networks

Štěpán, Petr January 2014 (has links)
This work deals with the modern trends in FTTX, but mainly focuses on FTTH, who represents the connecting of fiber to the homes of the participants. Sum up the basic problems of communication on the optical fibre, followed by comparison with other types of access networks. Another part is the analysis of the problems of construction and a description of the optical network topologies and technologies used in FTTH. In following chapter are characterized active and passive elements forming AON and PON networks. Next part deals with the study of the most common services that can be on the optical access network to operate. They are mainly associated with the TriplePlay services. An integral part of the project is the study of management and supervision optical networks. In the main part is created real model situation where is the requirement for the creation of optical access networks with broadband of TriplePlay, followed by selection of appropriate options and detailed project with a selection of active and passive elements with economic balance.
40

Modélisation et optimisation de la couche optique de réseaux sur puce / Modeling and optimization of optical layer networks on chip

Channoufi, Malèk 28 February 2014 (has links)
Dans le cadre du développement de SoC (Systems-on-Chip) complexes, l'interconnexion des différent IP matériels (Intellectual Property), très distants à l'échelle d'un circuit intégré (typiquement quelques centimètres) et devant s'échanger des volumes de données parfois important, incite, pour des raisons de débit, de latence, de pertes et de consommation, l'adoption d'une méthodologie de conception adéquate pour réaliser des systèmes de plus en plus flexibles. Afin de répondre à ces nouvelles difficultés de conception, de nombreuses recherches ont fait émerger le concept de réseau optique sur puce (Optical Network-on-Chip ou ONoC).Dans cette thèse une étude détaillée d'une nouvelle architecture d'un réseau optique sur puce a été faite. La conception de ce réseau repose sur 2 paradigmes d'interconnexion: concevoir l'architecture dans le cadre d'une puce en 3D et l'empilement en plusieurs niveaux des guides d'onde optique dans la couche réseau optique sur puce. L'élément clef de cette architecture est un microrésonateur à plusieurs niveaux de guide d'onde (Si/SiO2). De ce fait, une étude détaillée sur le comportement optique de ce composant avec des modèles mathématiques et des simulations FEM a été faite dans le but d'optimiser la perte de puissance optique, le nombre des niveaux des guides d'onde empilés et la consommation d'énergie.Après avoir détaillé le fonctionnement de réseau multi-niveaux sur puce proposé "OMNoC", son protocole de routage a été étudié avec le simulateur NS-2, puis optimisé, rédiger et étudier avec C++ et l'outil Parsec Benchmark. Enfin et en tenant compte des études faites sur le comportement optique des guides d'onde et le protocole de routage, une étude desperformances comparatives avec des autres architectures a été élaborée montrant ainsi les avantages et les limites d'une telle méthodologie d'interconnexion. / The developing of complex System on Chip "SoC" interconnecting different cores IP distant in micrometer chip scale, needs important data bandwidth , low latency and the best compromise between optical power loss and crosstalk. According to that, finding new methodology design is necessary to cope to those challenges.Using centric communication becomes the mainly solution to improve communication performance in system on chip and recently many researches are focusing on Optical Network on Chip 'ONoC'.In this thesis, a novel architecture of an optical network on chip is proposed, this architecture is reposed on 2 design paradigms: ONoC based 3D chip and multilevel waveguides based ONoC. The key element of this architecture is the multilevel microresonator (Si/SiO2) which is the optical switch of the network. Optical wave behavior in different geometries have been studied using FEM method in order to find compromise between optical power loss and crosstalk. Operation mode of this ONoC called "OMNoC" is explained, routing protocol is studied using NS-2 simulator too, then optimized and developed using C++ and Benchmark tool. After that and by using FEM results and adopted routing strategy, OMNoC performances are studied and compared with other network architectures proposed in ONoC literature. In conclusion and according to performances analysis and comparisons, OMNoC could be considered as a promising network architecture which offer scalability and give a compromise between optical power loss and crosstalk.

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