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Musa, Mohamed Osman Ibrahim. "Energy efficient IP over WDM networks using network coding." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/16644/.
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In this thesis we propose the use of network coding to improve the energy efficiency in core networks, by reducing the resources required to process traffic flows at intermediate nodes. We study the energy efficiency of the proposed scheme through three approaches: (i) developing a mixed integer linear programme (MILP) to optimise the use of network resources. (ii) developing a heuristic based on minimum hop routing. (iii) deriving an analytical bounds and closed form expressions. The results of the MILP model show that implementing network coding over typical networks can introduce savings up to 33% compared to the conventional architectures. The results of the heuristic show that the energy efficient minimum hop routing in network coding enabled networks achieves power savings approaching those of the MILP model. The analytically calculated power savings also confirm the savings achieved by the model. Furthermore, we study the impact of network topology on the savings obtained by implementing network coding. The results show that the savings increase as the hop count of the network topology increases. Using the derived expressions, we calculated the maximum power savings for regular topologies as the number of nodes grows. The power savings asymptotically approach 45% and 23% for the ring (and line) and star topology, respectively. We also investigate the use of network coding in 1+1 survivable IP over WDM networks. We study the energy efficiency of this scheme through MILP, a heuristic with five operating options, and analytical bounds. We evaluate the MILP and the heuristics on typical and regular network topologies. Implementing network coding can produce savings up to 37% on the ring topology and 23% considering typical topologies. We also study the impact of varying the demand volumes on the network coding performance. We also develop analytical bounds for the conventional 1+1 protection and the 1+1 with network coding to verify the results of the MILP and the heuristics and study the impact of topology, focusing on the full mesh and ring topologies, providing a detailed analysis considering the impact of the network size.
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Yau, Victor. "WDM network design and destination conflicts." Thesis, University of Canterbury. Computer Science, 1996. http://hdl.handle.net/10092/8387.
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The parallel use of multiple channels in a WDM star network means that too many packets may simultaneously arrive for the same destination station, necessitating the implementation of a destination-conflict-resolution function somewhere within the network. This thesis considers explicitly, the placement of the destination-conflict-resolution function which specifies the location(s) where it should be performed, and when it should be performed. Traditional placements in which the function is located at all user stations and performed either before packet transmission (using the request-schedule-then-transmit principle) or after a destination conflict has been detected (using the detect-and-retransmit-if-lost principle), is compared with a central placement in which only one central station located at the entrance to the star coupler is responsible for detecting conflicts and re-scheduling the arrival times of “otherwise lost” packets whilst they are en route to their destinations, so that they arrive when their destinations free to receive them.
The networks are evaluated considering their delay and throughput characteristics, the computational complexity of their protocols, and their hardware demands. All numerical results were produced using AKAROA an object-oriented parallel simulation package developed by us for automated precision control of steady-state estimates and automated parallel execution of quantitative simulations. The results presented suggests that significant performance improvements are achievable with the central placement since destination conflicts are resolved without having to retransmit packets nor waiting until the end of a request-broadcast-and-schedule phase before a given packet can be transmitted. The central station works with Space Division Multiplexed signals, just before they enter the star coupler. Its implementation is therefore simpler than when all stations are charged with this task, each of which has to attend to multiple WDM channels. Only “otherwise lost” packets are buffered so the network has low buffer memory requirements.
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THAKER, DHAVAL V. "Multicasting in a Partially Tunable Broadcast WDM Network." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010430-154109.
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We consider the problem of scheduling multicast packet transmissions in a broad-cast single hop WDM network. Tunablity isprovided only at the one end, namely at thetransmitter. Our objective is to schedule multicast transmission in a tunable transmitterand a fixed receiver broadcast WDM network. In a Single-hop WDM network having fixedreceivers, the unicast and multicast traffic can be scheduled by a single scheduling algorithm.If so, the problem of scheduling multicast traffic, reduces to a Wavelength Assignmentproblem as to assign wavelengths to the fixed receivers before scheduling multicast packettransmission. A receiver-to-channel assignment has to meet two con icting requirements.The first requirement is to minimize the number of retransmissions. The retransmissionsare caused when members of a multicast group are assigned to different wavelengths andthe group traffic is transmitted on each of these wavelengths. The second requirement is tomaximize the channel utilization, to balance the incoming traffic optimally on all the avail-able wavelengths. We address a fairly general version of the problem as we allow arbitrarytraffic demands and arbitrary multicast group membership distribution. First, we definethe Wavelength Assignment problem formally and prove it to be NP-Hard problem. Sincethe problem is intractable in nature, next we develop different heuristics. The heuristicsare evaluated based on their success in achieving the tradeoff between lower running timerequirements and the accuracy of the obtained result to the optimum solution. Finally, wevary the different system parameters such as the number of nodes, channels and multicastgroups and analyze their in uence on the performance of the developed heuristics.
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Mao, Minjing, and 毛忞婧. "Design and analysis of survivable WDM optical network." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B4784968X.
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Optical networks with Wavelength Division Multiplexing (WDM) technology provide huge bandwidth to meet the ever-increasing traffic demand of the next generation Internet. But the high-speed nature of WDM networks also makes the network more vulnerable to failures. Even a single network failure for a very short duration can result in enormous loss of data. In this thesis, we concentrate on designing a survivable WDM network. In essence, survivability concerns two important aspects, fast fault detection and localization, and fast fault recovery.
We first study fast fault detection and localization in WDM optical networks. Our work is based on the notion of monitoring cycle (m-cycle). Compared with other fault detection schemes, an m-cycle based fault detection scheme provides fast fault detection and requires less number of expensive monitors. Aiming at further cutting down the implementation cost, we propose the notion of super monitor. Instead of having a dedicated monitor for each m-cycle, a single super monitor can be placed at the junction of a set of overlapped m-cycles. In this thesis, we formulate and solve the monitor placement problem.
We then focus on enhancing the capacity efficiency of fast fault recovery schemes. Shared backup path protection (SBPP) schemes can provide 100% protection against any single link failure. This is achieved by establishing a pair of link-disjoint active and backup paths upon each call arrival. The bandwidth on different backup paths can be shared for protecting different calls. In this thesis, a new SBPP scheme is designed based on a two-step routing approach, where the active and backup paths are sequentially optimized with different objectives in mind. We then shift our focus to design fast protection scheme for multicast/broadcast communications. To this end, we refine the existing concept of blue/red tree. Blue/red tree is a pair of spanning trees where the connectivity between the root and any destination node is ensured upon a network failure. In particular, two efficient integer linear programs (ILPs) are formulated for finding the optimal blue/red trees.
Last but not the least, we investigate the survivability in IP networks. We notice that existing efforts on IP fast reroute (IPFRR) are effective in enhancing the IP resilience. But the impact of IPFRR on the end-to-end TCP performance is ignored. Notably, path rerouting can interfere with the TCP congestion control mechanism and thus cause severe throughput degradation. To address this problem, we propose a duplicate acknowledgement (ACK) suppression scheme. The key idea is to detect whether an out-of-order packet arrival event is due to IPFRR or not. If it is due to IPFRR, duplicate ACKs triggered will be suppressed by the TCP receiver so as not to cause unnecessary slow down at the TCP sender.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
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Nikolayev, Maksym. "Contribution to the enhancement of the efficiency of IP-over-WDM networks by evaluating and attaining the limits of multilayer network planning." Thesis, Evry, Institut national des télécommunications, 2014. http://www.theses.fr/2014TELE0022/document.
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La quantité de données devant être transportée via les réseaux de cœur croit de près de 25% par an. Pour maîtriser les coûts, les différentes couches du réseau doivent mettre des informations en commun pour inclure de plus en plus de paramètres lors du dimensionnement du réseau. Cela s’appelle « dimensionnement multicouche ». Nous étudions le dimensionnement multicouche de réseaux statiques composés de deux couches utilisant la commutation en mode circuit (typiquement IP-sur-WDM). Nous proposons un modèle semi-analytique expliquant le comportement des algorithmes responsables de l’agrégation et du routage dans les deux couches. Ce cadre théorique permet de comparer les algorithmes de dimensionnement multicouche entre eux, mais aussi d’expliquer et d’améliorer leur efficience. Nous décrivons ensuite comment la contrainte de portée optique affecte les résultats d’un algorithme de dimensionnement multicouche. Enfin, nous expliquons comment ces résultats s'appliquent au dimensionnement des réseaux de nouvelle génération (dynamiques et hétérogènes en capacité optique)The traffic passing through core networks grows by nearly 25% each year. To bring the costs under control, the different network layers of the network should work together to include more and more parameters during the network planning phase. This is called “multilayer network planning”. We study the multilayer network planning of static networks composed of two circuit switched layers (typically IP-over-WDM). We propose a semi-analytical model explaining the behavior of algorithms responsible for aggregation and routing in both layers. This theory allows comparing multilayer planning algorithms between them, but also explaining and enhancing their efficiency. We then describe the impact of the optical reach constraint in WDM networks on the results of a multilayer planning algorithm. Finally, we explain how these results apply to the design of future networks (dynamic and with heterogeneous optical layers)
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Havliš, Ondřej. "Pasivní optické sítě WDM-PON." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219767.
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The work deals with optical access networks, passive optical networks, especially WDM-PON. Features a modern solution to connect users to the optical access network using optical FTTx connections. Describes the different types of FTTx connections, their parameters and construction technology. Practical work is a practical application of theory for the development of various design and simulation of WDM-PON networks. Each proposal includes the construction of technical solutions optical access networks, the technology used and the balance of the reduced pricing WDM-PON network. The penultimate part of the work consists of design models simulated WDM-PON networks by the simulation program OptSim. The conclusion deals with the evaluation of individual design and simulation of WDM-PON networks.
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Calonico-Soto, Alicia. "Influence of optical crosstalk on WDM all-optical network design." Thesis, University of Essex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327077.
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Zorgani, Nagib Youssef. "The Design of FTTH Network." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-221007.
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The aim of this thesis is to explain the problems of optical access networks with wavelength division multiplexers, main purpose is to demonstrate the difference between theoretical and real measurement. The work is divided into several thematic areas. The introduction outlines the basic of telecommunications, fiber optics lasers, single mode, multimode, lasers fibers cables & cores, splitters division multiplexing system, there are known solutions discussed fundamental wavelength multiplexes and their possible combinations. The following chapter deals with the active elements such as AON, PON, which are essential part xWDM systems such as optical lasers, detectors and amplifiers. Another chapter focuses on passive elements, which form a key part of the wavelength multiplex. Methods of measurement of WDM/PON networks are discussed in the following part. The next section describes the topology used active and passive optical networks. The penultimate part of the work consists of architecture & technology of xWDM such as GPON and WDM-PON networks and comparing their transmission parameters. The final part of the paper presents the results of practical experimental measurements of optical access networks with wavelengths division multiplex while these results are compared with the theoretical output & methods of Optical lost test, OTDR & LSPM, with advantage & disadvantage of every methods. The second part of practical is the draft to the connection resident housing units of 30 houses, boarding-house (10 rooms) and 2 shops, 20 km distant from exchange. With comparing the possibilities of two options- passive and active optical network- PON system – WDM- Wave multiplex. Suggest the possibility of measuring and monitoring the created network.
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Kang, Byungkyu. "Design of survivable WDM network based on pre-configured protection cycle." Connect to thesis, 2006. http://portal.ecu.edu.au/adt-public/adt-ECU2007.0015.html.
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Liu, Lida. "Hardware-Efficient WDM/SDM Network : Smart Resource Allocation with SDN Controller." Thesis, KTH, Kommunikationssystem, CoS, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-261155.
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Optical networking has been developing for decades and wavelength-division multiplexing (WDM) is the main technology used to carry signals in fiber-optical communication systems. However, its development has slowed because it is approaching the Shannon limit of nonlinear fiber transmission. Researchers are looking for multi dimensional multiplexing. Space-division multiplexing (SDM) is an ideal way to scale network capacities. The capacity of WDM/SDM network could be expanded to several times the capacity of WDM network but the active hardware devices may also increase by several times. This project aims to answer a practical question: How to construct a WDM/SDM network with less hardware resource? There is no mature research about WDM/SDM network yet. Therefore, the problem can be divided into two parts: (1) how to build a WDM/SDM network and (2) how to allocate resource and compute routes in such a network to minimize hardware resources. First, this thesis proposes a WDM/SDM node which has bypass connections between different fibers and architecture on demand (AoD) to effectively decrease the number of active hardware devices within the node. Then, two types of networks were constructed: one with bypass connections in each node and another one without any bypass connections. These networks were under the control of a software defined network (SDN) controller. The controller knew the wavelength resources within the networks. Several algorithms were applied to these networks to evaluate the effect of a bypass network and to identify the desired characteristics (to find short length path and decrease the probability of spectrum fragmentation) of an algorithm suitable for a network with bypass connections. The results of applying the proposed algorithms in two networks proved that the bypass connections increased the blocking probability in small topology but did not affect the results in large topology. The results in a large-scale network with bypass network were almost the same as the results in a network without bypass connections. Thus, bypass connections are suitable for large-scale network.Optiskt nätverk har utvecklats i årtionden och våglängdsdelningsmultiplexering (WDM) är den viktigaste tekniken som används för att bära signaler i fiberoptiska kommunikationssystem. Utvecklingen har dock minskat eftersom den närmar sig Shannon-gränsen för olinjär fiberöverföring. Forskare letar efter flerdimensionell multiplexering. Space-division multiplexing (SDM) är ett idealiskt sätt att skala nätverkskapacitet. Kapaciteten för WDM / SDM-nätverk kan utökas till flera gånger WDM-nätverkets kapacitet, men de aktiva hårdvaraenheterna kan också öka med flera gånger. Projektet syftar till att svara på en praktisk fråga: Hur konstruerar jag ett WDM / SDM-nätverk med mindre hårdvara? Det finns ingen mogen forskning om WDM / SDM-nätverk än. Därför kan problemet delas in i två delar: (1) hur man bygger ett WDM / SDM-nätverk och (2) hur man fördelar resurser och beräknar rutter i ett sådant nätverk för att minimera hårdvaruressurser. Först föreslår denna avhandling en WDM / SDM-nod som har förbikopplingsanslutningar mellan olika fibrer och arkitektur på begäran (AoD) för att effektivt minska antalet aktiva hårdvaraenheter inom noden. Sedan konstruerades två typer av nätverk: en med bypass-anslutningar i varje nod och en annan utan några bypass-anslutningar. Dessa nätverk kontrollerades av en mjukvarudefinierad nätverkskontroller (SDN). Styrenheten visste våglängdsresurserna i nätverket. Flera algoritmer applicerades på dessa nätverk för att utvärdera effekten av ett förbikopplingsnätverk och för att identifiera de önskade egenskaperna (för att hitta en kort längdväg och minska sannolikheten för spektrumfragmentering) av en algoritm som är lämplig för ett nätverk med bypass-anslutningar. Resultaten av att tillämpa de föreslagna algoritmerna i två nät visade att förbikopplingsförbindelserna ökade blockeringssannolikheten i liten topologi men inte påverkade resultaten i stor topologi. Resultaten i ett storskaligt nätverk med bypass-nätverk var nästan samma som resultaten i ett nätverk utan bypass-anslutningar. Bypassanslutningar är således lämpliga för storskaliga nätverk.
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Lásko, Jan. "Návrh sítě WDM-PON." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219458.
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The work is focused on the design of optical network of technologies WDM-PON. The work describes passive technologies like APON, GPON, EPON etc. Theoretical part is focused on elements used in WDM-PON networks like transmitters, receivers. Distributional part is focused on optical fibers. The work also describes the quality of service QoS and Triple play. Practical part is focused on attenuation balance, choice of locality and description of individual parts of optical network. It is further described the technology of microtubing and financial analysis. In end of the work there is a simulation of optical network for 96 clients in the distance of 1 60 km described.
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Bobkovič, Peter. "Širokopásmová FTTx přípojka na architektuře WDM - PON." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218328.
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This masters thesis is focusing on the issue of passive optic access networks. It is dealing with the limiting factors for broadband connections, especially attenuation of fibre optics and dispersion. It is also dealing with most commonly used standards of passive optic networks. It clarifies the issue of wavelength-division multiplexing, its advantages and disadvantages, used standards, various types of components for the WDM-networks, their characteristics, application etc. In the practical part of the work you can find the measuring and diagnostics of the passive optic network EPON. It contains measuring by the direct method OLTS, measuring by the Pon Power Meter and optic reflectometer OTDR. At the end I am dealing with the measuring of splitter in the rate of 1:16.
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Gauger, Christoph. "Novel network architecture for optical burst transport." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-28560.
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Drummond, Andre Costa. "Agregação de tráfego em redes ópticas com multiplexação por comprimentos de onda." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/275776.
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Orientador: Nelson Luis Saldanha da FonsecaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação
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Resumo: Em redes ópticas com multiplexação por comprimento de onda (WDM), a alocação de banda passante ocorre em múltiplos da capacidade de um comprimento de onda, que, nos dias de hoje, corresponde a 40 Gbps. No entanto, a demanda de banda passante dos fluxos em redes IP sobre WDM é da ordem de Mbps, o que é, consideravelmente inferior a capacidade de um comprimento de onda. Para a utilização eficiente da grande capacidade disponível em redes WDM, agrega-se diversos fluxos com pequena demandas de banda em caminhos ópticos compostos pelos comprimentos de onda. A referida agregação é realizada pelo mecanismo chamado agregação de tráfego (em Inglês, traffic grooming). Para a agregação, é necessário, que se defina a rota a ser utilizada para o estabelecimento de uma conexão entre pares comunicantes, bem como o comprimento de onda a ser utilizado ao longo da rota, ou seja, é necessário resolver o chamado problema de roteamento e alocação de comprimento de onda (do Inglês, routing ou wavelength assignment, usualmente abreviado por RWA). Por outro lado, aplicações emergente em e-Ciência e novas aplicações multimídia demandam banda passante superior 'a capacidade de um comprimento de onda, requerendo que o fluxo seja transmitido em vários caminhos ópticos, possivelmente por rotas distintas, o que traz novos desafios, inclusive para os mecanismos de agregação de tráfego. Esta tese investiga diversos problemas em agregação de tráfego e propõe soluções originais para os mesmos. Propõe-se solução para o problema de coloração de grafo auxiliar para a resolução do problema RWA, através da recente Teoria de Complexidade Parametrizada, a fim de se reduzir a complexidade computacional da solução, tornando-a escalável. Introduzem-se, também, algoritmos para a resolução do problema de agregação dinâmica de tráfego, que consideram, parcialmente, a topologia da rede, para se promover a escalabilidade da solução. Tais algoritmos promovem, adicionalmente, bloqueio balanceado entre os diversos pares comunicantes na rede (justiça de bloqueio). Propõem-se, por último, algoritmos para agregar tráfego quando os fluxos demandam maior quantidade de banda passante do que a capacidade de um canal, através do roteamento por múltiplos caminhos, tanto para cenários envolvendo um único domínio como para cenários envolvendo múltiplos domínios. A solução proposta, redunda em maior robustez à falhas
Abstract: In wavelength division multiplexing (WDM) networks, the great discrepancy between the bandwidth demand of Internet Protocol (IP) flows (of the order of Mbps) and the bandwidth availability in one wavelength, which currently can be 40 Gbps, has motivated the adoption of techniques, called traffic grooming, for the efficient transmission of these flows. Traffic grooming aggregates flows with small bandwidth demand in a wavelength. For that, it is necessary to determine the route to be used for the establishment of a requested connection between a source and a destination as well as the wavelength to be allocated to this connection. These are determined by the solution of the so called routing and wavelength assignment problem (RWA). Moreover, the bandwidth requirement of some emerging e-Science and multimedia applications exceed the capacity of one wavelength requiring that a requested connection be established using multiple wavelengths and possibly multiple paths. In this Thesis, several issues in traffic grooming are addressed. An algorithm based on the recent Parametrized Complexity Theory is proposed for solving efficiently the graph coloring problem which is one of the steps in the solution of the RWA problem. Additionally, efficient algorithms which consider partially the topology of the network (zones) are introduced for producing balanced blocking among source destination pairs. Moreover, algorithms for providing connectivity to requests with bandwidth demand greater than the capacity of a wavelength are proposed. These algorithms use multiple paths for both requests that transverse multiple domains and those which do not. Furthermore, robustness to link failure is increased by using these algorithms
Doutorado
Doutor em Ciência da Computação
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Sharma, Ameeth. "Performance comparison of two dynamic shared-path protection algorithms for WDM optical mesh networks." Diss., Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-01262009-141918/.
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Glatty, Roman. "Introduction to TDM/WDM flexibility in optical access network : physical layer design and resource allocation optimization." Rennes 1, 2008. http://www.theses.fr/2008REN1E001.
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Passive Optical Networks (PON) which offer 1 Gbit/s of symmetrical bitrate shared among 32 or 64 clients are currently deployed in USA, in far east Asia and in Europe. Two world major standardization institutions – International Telecommunication Union (ITU) and Institute of Electrical and Electronics Engineers (IEEE) – have already created task force groups to normalise next generation PON which will be able to carry a 10 Gbit/s symmetrical bitrate. To manage in an efficient way such capacity, dynamic mechanisms of resources repartition need to be applied. In this context, this thesis focuses on flexible optical access networks which enable transmission with dynamic bandwidth repartition in the time (TDM) and frequency (WDM) domains. The document has been organised as follows : A first part contains the state of art of optical components and architectures which enable flexible bandwidth repartition. A second part presents three innovative architectures of flexible access networks that have been designed and realised in the laboratory. The last part focuses on the network behaviour under various traffic conditions. A short summary of the physical layer evaluation and the traffic simulations as well as a perspective of further development have been included into the conclusion chapter. In the annex we attach publications issued from the works in the frame of this thesisLes réseaux d’accès optiques (PON), offrant un débit symétrique d'au moins 1 Gbit/s partagé par 32 ou 64 clients, sont en cours de déploiement aux Etats-Unis, en Asie et en Europe. Les deux plus grandes organisations mondiales chargées de la normalisation des solutions en télécommunication (UIT et IEEE) ont déjà créé des groupes de travail sur le thème du réseau PON de nouvelle génération, qui offriront le débit de 10 Gbit/s symétrique. Pour gérer de manière efficace un tel débit, les mécanismes dynamiques de partage de la bande passante doivent être mis en place. Dans ce contexte, cette thèse se concentre sur les réseaux d’accès flexibles qui permettent une répartition dynamique des ressources dans les domaines temporel (TDM) et fréquentiel (WDM). Le mémoire de thèse a été organisé comme suit : Une première partie décrit l’état de l’art sur les composant optiques et sur les architectures flexibles proposées jusqu’à aujourd’hui par différents laboratoires de recherches. La partie suivante présente trois architectures innovantes, qui permettent de mettre en œuvre une gestion dynamique de la bande passante. La couche physique liée à ces architectures a été étudiée, d'une part à l'aide de simulations pour en évaluer les performances et, d'autre part, au travers de réalisations expérimentales au laboratoire, afin de valider les résultats obtenus au cours des simulations. Une dernière partie se focalise sur les aspects trafic, avec l'étude du comportement de ces solutions de réseau sous différentes charges en fonction du profil de trafic émis par les clients. A la fin du document, le résumé des résultats obtenus ainsi que des perspectives pour la suite de ces études sont présentés. Les publications dans des conférences nationales et internationales issues de cette thèse ont été regroupées en annexe
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Poudel, Sunil. "Study on Fault Detection andLocalization for Wave length Division Multiplexing Passive Optical Network." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-129299.
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Wavelength division multiplexing passive optical network (WDM-PON) can meet growing bandwidth demand in access network by providing high bandwidth to the end users. Failure in the access network is becoming critical as a large volume of traffic might be affected. Therefore, an effective supervision mechanism to detect and localize the fault is required to shorten the service interruption time. Meanwhile, open access provides a certain freedom for end users to choose the service and hence boosts competition among service/network providers. On the other hand, to offer open access in WDM-PON could result in a substantial change on architectural design, e.g., multiple feeder fibers (FFs) instead of a single one may be required to connect different service/network providers. Consequently, the traditional supervision mechanisms don’t work properly in open WDM-PON. To fill in this gap, several fault supervision mechanisms to support open access in WDMPON are proposed in this thesis. They can be applied to both disjoint and co-located FF layout where the choice of providers is done through wavelength selection. The feasibility of such solutions has been validated by evaluating transmission performance. We have carried out simulations in VPItransmissionMaker for different deployment scenarios. The results have confirmed that no significant degradation of the transmission performance is introduced by the proposed monitoring schemes compared to the benchmark, where no any fault supervision method is implemented.
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Fang, Xiaojun. "Nonreciprocal effects and their applications in fiber optic networks." Diss., Virginia Tech, 1996. http://hdl.handle.net/10919/40337.
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Nonreciprocity is a fundamental property of networks. Unlike electronic networks theory, optical network theory is still a field to be investigated. Lightwave systems, including fiber optic and integrated optic, are becoming more and more complex, new function blocks ( or components) and networking strategies are very important for future highly integrated lightwave circuits. Several common nonreciprocal optical effects studied in this disseration and several basic applications to fiber components and fiber optic metrology systems analyzed.
The common optical nonreciprocal phenomena include the Faraday effect, Sagnac effect, Fresnel drag effect, nonlinearity or asymmetric geometric structure-induced nonreciprocity, and some pseudo nonreciprocity. The best-known application of nonreciprocity to optical components is the isolator, and the known nonreciprocity-based fiber optic sensors are the fiber optic gyroscope and the fiber optic current sensor. The major difficulty in forming a general optical network theory is the complexity of optical signals compared to the electrical signal, because each light signal consists of four independent parameters, all of which changing during transmission. Fortunately, most optical signals can be classified into intensity-based and phase-based systems, and the Jones matrix technique is the ideal tool for describing the intensity-based system.
Several reciprocity-insensitive structures designed and analyzed in chapter 3. The performance of the intensity-based reciprocity-insensitive structure (IRIS) was employed successfully in a fiber optic current sensor for stabilizing the signal from birefringence influences in chapter 5. A variable-loop Sagnac interferometer was designed and applied to distributed sensing in chapter 6, and the reciprocity-insensitive property of the Sagnac interferometer was preserved. Polarization independent isolators and wavelength division multiplexers were also realized by employing suitable nonreciprocal effects and were discussed in chapter 2 and chapter 4, and their feasibilities were verified by experiment. The primary contributions of this dissertation are the study of common nonreciprocal optical effects and demonstration of several basic applications to fiber components and fiber metrology systems.Ph. D.
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Nogueira, Pedro Henrique Tolentino de Melo. "Algoritmos para alocação de rota e comprimento de onda com restrições de energia e da camada física em redes ópticas." Universidade Federal da Paraíba, 2014. http://tede.biblioteca.ufpb.br:8080/handle/tede/6125.
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This dissertation proposes two new algorithms for routing and wavelength allocation EA-RWA (Energy Aware Routing and Wavelength Assigment) and IEA-RWA (Impairment and Energy Aware Routing and Wavelength Assigment). The algorithms have the characteristic, improve energy efficiency in dynamic transparent optical networks, the first being simpler, because it does not care about the imperfections of the physical layer. The EA-RWA is compared with a traditional RWA / classic that does not take into account at the time of admission of the physical layer connections restrictions nor energy consumption algorithm. Have the IEA-RWA is compared with a RWA algorithm that takes into account the constraints (IA-RWA) physical layer. Numerical simulations show that the IEA-RWA performs better in many aspects
Esta dissertação propõe dois novos algoritmos de roteamento e alocação de comprimento de onda, a saber, o EA-RWA (Energy Aware Routing and Wavelength Assigment) e o IEA-RWA (Impairment and Energy Aware Routing and Wavelength Assigment). Os algoritmos terão como característica, melhorar a eficiência energética em redes ópticas transparentes dinâmicas, sendo o primeiro mais simples, pois não se preocupa com as imperfeições da camada física. O EA-RWA é comparado com um algoritmo RWA tradicional/clássico que não leva em conta, no momento de admissão de conexões, restrições da camada física e nem consumo de energia. Já o IEA-RWA é comparado com um algoritmo RWA que leva em conta restrições da camada física (IA-RWA). As simulações numéricas mostram que o IEA-RWA apresenta melhor desempenho em vários aspectos
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Celino, Daniel Ricardo. "Proposta e análise de redes WDM-PON empregando auto-alimentação e dupla cavidade óptica." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18155/tde-22092017-093305/.
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Nas topologias de redes WDM-PON (Wavelength Division Multiplexed Passive Optical Network) baseadas em transmissores colorless, isto é, transmissores que possam operar em uma grande gama de comprimentos de onda, que empreguem técnica de auto-alimentação e reuso de comprimento de onda, tem despertado grande interesse devido a sua comprovada eficiência, granularidade e custo reduzido em relação às alternativas. Entretanto, o alcance destas redes é limitado pelo emprego de remodulação, devido a dependência existente com a qualidade dos sinais a serem remodulados. Neste cenário, mantendo-se uma melhor relação custo-benefício, taxas de operação típicas são da ordem de 1,25, e 2,5 Gb/s (20 quilômetros). Neste trabalho é investigada uma nova topologia que combina as técnicas de auto-alimentação e reuso de comprimento de onda, bem como, utiliza um circuito de dupla cavidade óptica, possibilitando um reforço no apagamento óptico e manutenção do estado da polarização no percurso de recirculação da cavidade externa, objetivando uma melhora na qualidade dos sinais a serem remodulados, possibilitando altas taxas de transmissão e um maior alcance da rede. Nesta topologia, amplificadores ópticos semicondutores refletivos são utilizados como transmissores colorless, por meio da emissão espontânea amplificada, garantido assim uma redução no custo da rede óptica de acesso. Como metodologia adotada, inicialmente foram realizadas caracterizações ópticas no ambiente de simulação, validação da palheta configurada no simulador com resultados experimentais e avaliações da topologia em taxas simétricas de 1,25 Gb/s. Ademais, são conduzidas análises comparativas entre a topologia proposta frente a topologias disponíveis na literatura no estado da arte. Com os resultados obtidos, acredita-se que essa proposta atende aos requisitos de capacidade agregada e custo reduzido, podendo alcançar taxas de transmissão de até 10 Gb/s utilizando transmissores de baixa complexidade, características essenciais para impulsionar a implementação de redes de acesso óptico.WDM-PON topologies based on colorless transmitters employing self-seeding and wavelength-reuse techniques have attracted a great deal of interest because of its well known efficiency, granularity and reduced cost, when compared to other alternatives in the literature. Nevertheless, the network reach is limited by the use of remodulation scheme. Maintaining an adequate cost-benefit relation requires typical operating rates of the order of 1.25 Gb/s to 2.5 Gb/s over 20 km of SSMF. In the above framework, we investigate a new topology which combines self-seeding and wavelength-reuse techniques, but also employs a scheme to reinforce the data erasure in the optical carrier, simultaneously providing state of polarization (SOP) maintenance in the external cavity recirculation path. The proposed configuration improves the quality of the signals to be remodulated, thus allowing high rate and broader reach. Specifically, in our work, reflective semiconductor optical amplifiers are employed as colorless transmitters, by using their own amplified spontaneous emission as a seed to provide the optical carrier. Optical analysis were performed in a simulation environment, including self-seeding layout validation by comparison to experimental results at the symmetric transmission rate of 1.25 Gb/s. Next, comparative analysis are conducted between the topology proposed in this work and topologies in the state of the art, found in the literature. According to the results, we believed that the proposal meets the requirements of aggregate capacity and reduced cost, being able to reach transmission rates of up to 10 Gb/s by using transmitters of low complexity, essential features to drive optical access networks implementation.
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Triay, Marquès Joan. "Architectures and protocols for sub-wavelength optical networks: contributions to connectionless and connection-oriented data transport." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/48634.
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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.
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Valdivia, Nereida Celina Llerena. "Roteamento de tráfego e alocação de recursos em redes ópticas WDM com base em economia de energia." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18155/tde-06012015-161005/.
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O crescimento do tráfego de serviços de telecomunicações tem aumentado o consumo de energia e, em consequência, aumentado as emissões de CO2 que tem efeitos nocivos sobre o meio ambiente. É assim que a economia de energia torna-se um fator chave no planejamento de redes de telecomunicações. Para garantir a disponibilidade e confiabilidade, as redes possuem arquitetura redundante e são projetadas para suportar a demanda de pico de tráfego. Redes com mecanismos de proteção como proteção dedicada de caminhos (DPP), proveem caminhos alternativos para cada demanda de conexão. Os elementos da rede que suportam esses caminhos estão em estado ativo (consumindo energia), apesar de, na maior parte do tempo, não transportarem tráfego efetivo. Um método para diminuir o gasto de energia é utilizar roteamento adaptado à carga real de tráfego baseado em modo suspenso (estado de baixo consumo de energia que pode passar a estado ativo rapidamente). Assim, o tráfego é roteado com vistas à maximizar a quantidade de componentes que são parte de caminhos de proteção, que podem ser postos em modo suspenso. Neste trabalho, as redes usadas para os testes são a rede europeia Cost239, a rede estadunidense UsNet e a rede brasileira Ipê. Abordamos o problema de economia de energia em redes WDM com DPP através de quatro estratégias de roteamento. Cada uma tem objetivos diferentes, a Shortest Path-DPP (SP-DPP) faz o roteamento por caminho mais curto, a Energy Aware-DPP (EA-DPP) aloca as demandas por enlaces que estejam ativos, a Energy Aware-DPP with Mixing (EA-DPP-MixS) evita que caminhos principais sejam roteados por enlaces que já são parte de caminhos de proteção e a Energy Aware-DPP with Differentation (EA-DPP-Dif) evita a mistura de caminhos por um mesmo enlace. Em nossas simulações computacionais observamos que a EA-DPP-Dif economiza energia de maneira eficiente, mas a probabilidade de bloqueio aumenta. A EA-DPP-MixS diminui o bloqueio em detrimento da energia economizada. Já a SP-DPP e a EA-DPP são menos eficientes na diminuição da energia consumida. É assim que propomos um roteamento com busca de recursos mais ampla, usando cada uma das estratégias. A proposta será chamada de roteamento intensivo. A EA-DPP-Dif-Intensivo diminui a probabilidade de bloqueio e economiza energia mediante modo suspenso. Neste trabalho, analisamos o desempenho das estratégias para cada uma das redes e avaliamos o impacto da energia economizada sobre a probabilidade de bloqueio. A proposta de roteamento i>intensivo diminui a energia consumida em até 50%, diminuindo a probabilidade de bloqueio. Porém, os resultados estão diretamente relacionados com a carga de rede e as características particulares da topologia de cada rede.The growth of data traffic in telecommunication networks has increased energy consumption and hence increased CO2 emissions, with harmful effects on the environment. Thus, energy saving becomes a key and a differential factor when planning telecommunication networks. In order to guarantee availability and reliability, core networks have redundant architecture and are designed to support peak-hour traffic demand. Networks with dedicated path protection (DPP) mechanisms provide alternative paths for each connection request. Network elements supporting these paths are in active state (consuming energy), although most of the time they dont carry traffic. One technique to decrease energy waste is by adaptive real traffic routing using sleep mode (a low energy consumption state which is able to rapidly change to an active state). Thus, traffic is routed in order to maximize the amount of network components used by protection paths, which can be set in sleep mode. In this work, European Cost239, American UsNet and Brazilian Ipê networks were used in computational simulations. We addressed the energy saving problem in WDM networks with DPP through four routing strategies, each with different goals. The Shorthest Path-Dedicated Path Protection (SP-DPP) technique uses shortest path for routing, Energy Aware-Dedicated Path Protection (EA-DPP) allocates demands in active links, Energy Aware-Dedicated Path Protection with Mixing (EA-DPP-MixS) prevents primary paths to be formed by links that are already part of the protection paths and Energy Aware-Dedicated Path Protection with Differentation (EA-DPP-Dif) prevents mixing primary and protection paths through the same link. We observe that EA-DPP-Dif efficiently saved energy, however blocking probability has increased. EA-DPP-MixS reduced blocking rather than saved energy. At least, SP-DPP and EA-DPP are less efficient in reducing energy consumption. Hence, we propose a wider resource search routing, the in-depth routing, using each of these strategies. Thus, EA-DPP-Dif-In-depth decreased blocking probability while maintaining energy saving through sleep mode. In this work, we analyze the strategies performance for each network and evaluate the impact of energy saved on the blocking probability. Our in-depth routing strategy reduced the energy consumption up to 50%, decreasing blocking probability. However, the results are directly related with the network load and the specific properties of each network topology.
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Čech, Martin. "Optické zesilovače pro metropolitní a přístupové sítě." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-218964.
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Aim of this Master´s thesis is to describe and compare most common types of optical amplifiers used in today’s networks. The first section focuses on problematic of optical transmissions and phenomenon which cause degradation of transmitted signal. It is also explained in this section why there is a need to deploy optical amplifiers. Next section describes basic principles, structure and properties of individual types of optical amplifiers. Following section describes simulations which were made to compare the performance of transmission systems with each individual type of optical amplifier. The last section contains a design of optical metropolitan network with wavelength multiplex. Based on simulations from preceding part best amplifier type and optimal amplifier placement was selected. Functionality of the design was tested and simulations described in final section.
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Kakkar, Aditya. "Theoretical Investigation of a new OFDM Access-Network Topology (OTONES)." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-128712.
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Recent studies on growth of telecomm sector depict an ever rising demand for high bandwidth applications such as on-line gaming, high definition television and many more. This demand is coupled with increase in internet connected utilities per house hold - each requiring a portion of bandwidth. The fast development of broadband telecommunication services calls for an upgrade of access infrastructure. This challenge could be met by technologies such as Fiber-To-The-Home/Building (FTTH/B) point-to-multipoint (P2MP) optical access networking. Further, FTTH is also widely regarded as a future proof solution for broadband telecommunication services within scientific and industrial sectors. This has encouraged large amount of research and development throughout the globe to find optimal topologies for FTTH. OFDM based optical access network topology abbreviated as OTONES is an ongoing EU FP 7 project under the PIANO+ framework. The OTONES project addresses the next generation optical access networking on the basis of Orthogonal Frequency Division Multiplexing (OFDM) and Orthogonal Frequency Multiple Access (OFDMA), with special provision for reduced complexity and signal processing aspects of the subscriber side terminals (ONUs). This thesis focuses on the theoretical investigation of OFDM based optical access network topology OTONES. The thesis provides an in depth view of the salient aspects of the topology and formulates the key requirements of OTONES topology. The investigation primarily delves on two important aspects of the topology. First, finding the optimal analog circuitry for the optical network unit (ONU). Second, finding the optimal operation regime for the topology and hence optimizing the system level concept. In this thesis, we show that the requirement of an analog circuitry originates from the need of successive up-conversions in OTONES topology which also produces image spectrum. This image spectrum causes a 3 dB loss in power and spectral efficiency in absence of a proper image rejection circuitry. Thus, we discuss the generic SSB generation methods for efficient image rejection. Novel Bedrosian method based on Bedrosian Theorem is established as a promising method for image rejection. We show that this method is an analog implementation of Hilbert Transform Method and does not involve any approximation. Both generic methods for SSB along with the Novel Bedrosian method are evaluated based on the criterion established for OTONES topology. Finally, optical filtering from the set of generic SSB method is proposed for the downstream path and Novel Bedrosian method is proposed for the upstream path. The tolerance limits for Novel Bedrosian method, are also established for its physical implementation. We further discuss the realistic implementation of various components of the OTONES topology. We also establish the optimal operation regime of the full concurrent topology based on parameters such as input optical power, pilot tone separation and many more. Finally as a key feature of the thesis, we optimize the system level concept of the topology with the use of the proposed Novel Bedrosian Method as the optimal analog circuitry for OTONES topology and provide a region of optimal operation of the topology.
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Manfrin, Stilante Koch. "Proposta e implementação de um receptor optoeletrônico integrado para redes ópticas passivas (PONs) empregando multiplexação por divisão de comprimento de onda (WDM)." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-01122015-101424/.
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O presente trabalho descreve o desenvolvimento e implementação de duas configurações distintas de um receptor optoeletrônico integrado. A primeira configuração é similar a um projeto encontrado na literatura mas apresenta diversas modificações que lhe conferiram melhor desempenho em comparação ao projeto original. A segunda configuração é uma nova proposta deste trabalho. O receptor foi desenvolvido e implementado visando sua aplicação em redes de comunicações ópticas passivas (PONs) de alta velocidade comutadas a pacote, para possibilitar a utilização da técnica de multiplexação em comprimento de onda (WDM), aumentando assim a capacidade de transmissão da rede, em particular no ramo de ligação da rede de serviços com o usuário final, denominado rede de acesso. O principal objetivo do receptor aqui desenvolvido foi proporcionar uma sintonia rápida entre os canais disponíveis na rede, possibilitando sua seleção num tempo inferior àquele necessário para a transmissão de um único pacote de informação, diminuindo assim o atraso de sintonia e, por conseguinte, a perda de informação. Para tanto, os circuitos integrados implementados e caracterizados referem-se aos circuitos de chaveamento eletrônico e do amplificador de transimpedância das duas configurações investigadas. Os dados experimentais obtidos para as duas configurações confirmaram a previsão de chaveamento dos canais de entrada num intervalo de tempo da ordem de alguns nanosegundos, o que é totalmente compatível com a velocidade de transmissão das aplicações a que se destina este receptor (aproximadamente 5 Gbits/s). Adicionalmente, são apresentados os dados experimentais relativos à freqüência de corte, ganho direto, isolação, relação on/off e características de ruído dos circuitos implementados.The present work describes the design and implementation of two configurations of an integrated optoelectronic receiver. The first one is similar to a previously reported design but with some modifications to improve its performance. The second one is a new proposal of this work. The goal of the receiver design and implementation was its application in high bit rate packet-switched passive optical networks (PONs) employing the wavelength division multiplexing (WDM) technique to increase the network capacity, in particular on the connection branch of the network core with the final user, the access network. The main goal of the receiver design was to achieve a fast channel tuning, allowing a tuning time smaller than the required for the transmission of a single information packet, decreasing the tuning latency and, therefore, the rate of information packet loss. In order to accomplish this goal, the implemented and tested integrated circuits include the electronic switching circuit and the transimpedance amplifier for both configurations investigated. The measured data for both configurations confirm the expected input channel switching time results, of about a few nanoseconds, which is certainly useful for the expected bit rate of operation (approximate 5 Gbps). Additionally, experimental results concerning cutoff frequency and bandwidth, direct gain, isolation, on/off ratio, and noise characteristics of both implemented circuits are presented.
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Indre, Raluca Maria. "Analyse de performance des réseaux optiques à commutation en sous-longueur d'onde." Phd thesis, Télécom ParisTech, 2012. http://pastel.archives-ouvertes.fr/pastel-00838427.
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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.
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Amar, Djamel. "Performance assessment and modeling of flexible optical networks." Thesis, Evry, Institut national des télécommunications, 2016. http://www.theses.fr/2016TELE0007/document.
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Avec la croissance exponentielle du trafic lié au développement de la vidéo et des services d’Internet, les systèmes WDM évoluent régulièrement pour augmenter la capacité de la fibre optique. Pour atteindre cet objectif, les concepts d’«élasticité» et de grille WDM flexible ont été introduits et ont conduit au développement de nouveaux équipements optiques. Dans le cadre des réseaux flexibles, le dimensionnement de réseaux se complexifie, et les outils de dimensionnement traditionnels doivent être repensés. De plus, des problèmes stratégiques et technologiques apparaissent avec l’arrivée de ce nouveau concept. Presque tous les équipements optiques doivent être remplacés par d’autres mieux adaptés, entraînant un coût de déploiement additionnel. Ce travail propose et implémente des nouveaux outils mathématiques et logiciels de dimensionnement multicouche des réseaux optiques flexibles. Des cas d’usage intéressants à étudier dans le cadre des réseaux flexibles sont aussi identifiés et proposés dans cette thèse. De même, ce travail traite les problèmes principaux émanant de la flexibilité optique. De façon plus spécifique, nous étudions le problème de la fragmentation du spectre WDM flexible dans les réseaux d’opérateurs et proposons des solutions. De plus, nous proposons et évaluons un cas d’usage qui combine l’élasticité et la restauration optique du trafic dans un contexte multicouche. Enfin, nous identifions et proposons une solution au problème lié à l’utilisation des amplificateurs optiques dans les réseaux flexiblesWith the exponential growth of traffic driven by video and Internet services, WDM systems evolve regularly to increase optical fiber capacity. To meet the relentless need for capacity, advanced features have been integrated into optical layer leading to the notion of channel flexibility (datarate elasticity, flex-grid). In contrast, with the potential benefits that optical channel flexibility provides, network dimensioning gets even more complicated, and traditional dimensioning tools should be rethought. Moreover, some strategic and technological problems appear with optical layer flexibility. Almost, all legacy equipment in the optical layer needs to be replaced by greenfield and well-adapted equipment, which requires new investments. Furthermore, spectrum fragmentation has been identified as the main disadvantage of optical layer flexibility. This work proposes and implements different mathematical multilayer tools for network dimensioning with the aim of evaluating optical layer flexibility. It identifies profitable and advantageous use cases and networking scenarios that bring forward the interest of flex-grid and elasticity. This work also deals with the potential troubles of flexibility and provides solutions to them. Specifically, we thoroughly investigate spectrum fragmentation in operator network context, and propose some traffic engineering strategies. We propose and evaluate a new use case that combines datarate elasticity and optical restoration within a multilayer context. Finally, we state a new drawback of flex-grid technology regarding the use of legacy optical amplifiers with flex-grid networks and provide a solution to overcome this problem
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Horníček, Lukáš. "Nasazení FTTH v lokálních sítích." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220308.
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The master’s thesis is focused on the theoretical and practical issues of optical access networks. The first chapter of the thesis deals with the concept of the access networks known as FTTx. The second and third chapters focus on the principles and standardization of the active optical network AON P2P and the passive optical network TDM PON. The fourth chapter of the thesis focuses on the network WDM PON, wavelength multiplexes, solution concept and the LG-Ericsson EA 1100 platform. The fifth chapter of the thesis deals with the infrastructure of the optical paths for optical access networks. The sixth chapter of the thesis presents custom design of the headend for reception, processing and distribution of television broadcasting. Two custom access network solutions (AON P2P and WDM PON) for the town Bystřice nad Pernštejnem are presented in the seventh chapter. Case studies include the design of the optical paths infrastructure, central office infrastructure, end-user infrastructure, CAPEX/OPEX economic analysis and basic simulation in OptSim.
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Kandula, Ramesh. "Traffic grooming in WDM networks." Thesis, University of Hawaii at Manoa, 2003. http://hdl.handle.net/10125/7038.
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Wavelength Division Multiplexing (WDM) is the promising technology, which provides very wide bandwidths to support the exponential growth of lnternet traffic. A major part of the WDM network cost is the cost of opto-electronic switching components. By grooming low speed traffic connections efficiently onto the lightpaths, the cost of the WDM network can be reduced significantly. In the first part of the thesis, different WDM ring network architectures under a non-statistical traffic model are considered. The average number of Line Terminating Equipments (LTEs) required per node in these networks is significantly lower when compared to a ring network with opaque nodes. To utilize the bandwidth efficiently, the low speed traffic connections have to be rearranged by bridge and roll. In the second part of the thesis, grooming in WDM mesh networks under a static traffic model is considered. The main objective here is to minimize the total lightpaths required. A greedy heuristic algorithm for the lightpath minimization problem is presented.viii, 35 leaves
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Baldine, Ilia. "Dynamic Reconfiguration in Broadcast WDM Networks." NCSU, 1998. http://www.lib.ncsu.edu/theses/available/etd-19980723-230505.
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In this research we study the problems associated with dynamic reconfiguration of broadcast WDM networks.Adaptability to the changing traffic conditions is viewed as one of the key features of multiwavelength optical networks, and this is the first comprehensive in-depth study of this problem area.Our contribution consists of identifying the three main questions related to network reconfiguration: a) how to balance the load across multiple wavelengths; b) deciding when it is best to reconfigure the network and c) performing the actual reconfiguration in an efficient manner, that minimizes cell losses.We provide novel solutions to each of these problems.Our solutions consist of an algorithm we call GLPT, which balances the cell load across wavelengths, an optimal reconfiguration policy, derived from representing the problem as a Markovian Decision Process, and a class of retuning strategies that allow us to reconfigure the system.In addition, we perform a simulated comparison of static and dynamically reconfigurable networks in order to verify the validity of our approach.The simulation also provides us with valuable insights into the behavior of an adaptable optical network.
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Liu, Chang. "Survivability issues in WDM optical networks." [Ames, Iowa : Iowa State University], 2007.
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Rawat, Anuj. "Multicasting in all-optical WDM networks." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8763.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Torres-Herrera, Luis Alberto. "Protection mechanisms in WDM mesh networks." Göttingen Sierke, 2007. http://d-nb.info/993076513/04.
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CABALLERO, DIEGO RODRIGO VILLAFANI. "WDM-PON PASSIVE OPTICAL NETWORKS MONITORING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=23359@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
As redes ópticas passivas de nova geração 2 (NG-PON2) estão estudando e considerando o WDM-PON (Wavelength-Division-Multiplexed Passive Optical Networks) como a nova arquitetura para as redes de acesso, é provável que esta arquitetura seja adotada num futuro como o padrão. No entanto, algumas instalações já foram realizadas em todo o mundo, a maior parte delas na Coréia do Sul. Com o objetivo de reduzir os custos de operação (OPEX) e garantir a qualidade do serviço (QoS) um sistema de supervisão e localização de falhas é necessário. Neste trabalho é proposto e demonstrado um OTDR sintonizável (Optical Time-Domain Reflectometer) para realizar o monitoramento de redes WDMPON em serviço. O método apresentado é provado para diferentes fontes laser sintonizáveis CW (Continuous Wave) e utiliza um amplificador óptico semicondutor (SOA) como comutador para o sinal de prova. O sistema de monitoramento é provado experimentalmente numa rede WDM-PON simulada no laboratório a qual utiliza um AWG (Arrayed Waveguide Grating) como distribuidor. Os resultados foram melhorados utilizando diferentes métodos para mitigar os efeitos de interferência.
The Next Generation Passive Optical Network 2 (NG-PON2) is considering and studying wavelength-division-multiplexed passive optical networks (WDM-PONs) as the new architecture for access networks, this architecture is likely to be adopted in near future as standard. However some deployments have been achieved worldwide, most of them in South Korea. In order to lower the operational expenditure (OPEX) and guarantee quality-of-service (QoS) an in-service monitoring and fault localization system is required. We propose and demonstrate a tunable optical time-domain reflectometer (T-OTDR) for in-service monitoring of (WDM-PONs). The proposed method is proved for different continuous wave tunable laser sources (CW TLS), and uses semiconductor optical amplifier (SOA) as a switch for the probe signal. This monitoring system is experimentally proved in a simulated WDMPON employing a cyclic AWG (Arrayed Waveguide Grating) as wavelength distributor. We improve the results using different methods to mitigate the interference effects.
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Lee, Kayi (Edmund Kayi) 1977. "Wavelength partitioning in WDM ring networks." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86451.
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Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (leaves 34-36).
by Kayi Lee.
S.B.and M.Eng.
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Ribera, Carlos. "Energy Efficiency in IP over WDM Networks." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-129393.
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In the last decade, energy efficiency in backbone networks has become an important problem due to the significant growth in the Internet traffic. A very promising solution to solve this problem in Internet Protocol (IP) over Wavelength Division Multiplexing (WDM) networks is the Virtual Topology Adaptation approach, which permits adapting network resources by following a dynamic daily traffic profile. In this approach, virtual topology in the WDM layer adapts to the changes in the IP traffic, however, IP layer routing is following the conventional shortest path routing strategy being unaware of the lower layer adaptation. This thesis study aims to analyze the possibilities of power savings in WDM and IP layers in coordination and proposes multi-layer approaches for energy-efficient IP over WDM networks. Energy-efficient algorithms on a realistic scenario are considered where commercially available routers and their power consumption parameters are taken into account. Among these IP router systems, power consumption of single and multi-shelf systems are analyzed. Multi shelf system can accommodate multiple chassis in a rack while in the single shelf system only one chassis is employed. For networks with single-shelf routers, we propose an energy-aware IP traffic routing strategy in coordination with a virtual topology adaptation approach to save energy by following a dynamic daily traffic profile. Energy-efficient IP routing strategy offloads the traffic from the network resources running in extreme load levels resulting in stabilization in the virtual topology and improvement in energy-efficiency. It is shown that using this approach a considerable amount of energy is saved compared to the case of virtual topology adaptation without the IP layer involvement. Power consumption in networks composed of multi-shelf routers is studied and three different strategies for energy efficiency are proposed: one in the WDM layer, an Energy and Chassis-Aware Virtual Topology Adaptation (ECA-VTA), another in the IP layer, the Energy and Chassis-Aware IP Routing (ECA-IP), and a multi-layer strategy that combines ECA-VTA and ECA-IP (ECA-IP-VTA). Joint optimization of IP&WDM layers significantly reduces power consumption and number of changes in the virtual-topology compared with single-layer approach.
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Huang, Hong. "Hybrid and resilient WDM mesh optical networks." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/15751.
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Castleford, David. "Optical crosstalk in WDM Fibre-Radio networks /." Connect to thesis, 2002. http://eprints.unimelb.edu.au/archive/00000405.
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Shachaf, Y. "Coarse WDM wavelength-routed passive optical networks." Thesis, University of Hertfordshire, 2008. http://hdl.handle.net/2299/2628.
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The emergence of new bandwidth-intensive applications articulated by distance learning, online gaming, Web 2.0 and movie delivery by means of high-definition video, has ultimately justified the necessity of upgrading the access network infrastructure to provide fat-bandwidth pipelines at subscriber close proximity. Passive optical networks (PONs) are an emerging technology to deliver these services. This thesis presents innovative work performed towards the application of coarse wavelength division multiplexing (CWDM) to route communications to and from reflective optical network units (ONUs) incorporated in time and wavelength division multiplexed PONs. The concept of coarse and dense WDM grid integration and its adaptation in access networks to map, for the first time, selective closely-spaced wavelengths into coarse passband windows of Gaussian and flat-top arrayed waveguide gratings (AWGs), exhibiting coarse-fine grooming, is initially developed. This is followed by the identification of a new network architecture combining multiple PONs, using a coarse AWG to form a next-generation access network. A significant feature of this approach allows for time division multiplexing (TDM) and WDM PON technologies to be integrated through the 7 nm coarse passband windows of a single AWG, providing for interoperability and high scalability. The network performance through simulation, in the presence of polarisation-dependent wavelength shift and associated polarisation-dependent loss, shows the capability of a single optical line terminal (OLT) to access various physical PONs in 25 km proximity with multiple wavelengths through a single AWG router. This approach enables centralised bandwidth allocation and a smooth migration path between time-shared and densely-penetrated access networks. Furthermore, to demonstrate full-duplex operation, allowing for increased bandwidth utilisation of the reflective access network architecture, full-duplex functionality is achieved by using polarisation division multiplexing. This is implemented in the OLT by assigning each ONU downstream data and continues waves on orthogonal states of polarisation. Hence, by assuming the use of symmetrical broadband services, the novel multi-PON access network verifies its potential to double the bandwidth utilisation for each subscriber, allowing for increased bidirectional network throughput. In addition, an experimental test-bed is performed which demonstrates the core operation of the network being, by means of a readily-available 2.7 nm-wide AWG router. Hence, the practical feasibility of the new access network concept is demonstrated.
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Manley, Eric D. "Network coding for WDM all-optical networks." 2009. http://proquest.umi.com/pqdweb?did=1824846991&sid=4&Fmt=2&clientId=14215&RQT=309&VName=PQD.
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Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009.Title from title screen (site viewed October 15, 2009). PDF text: xx, 160 p. : ill. (some col.) ; 1 Mb. UMI publication number: AAT 3360160. Includes bibliographical references. Also available in microfilm and microfiche formats.
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Tiyachate, Ruarob. "Protection in survivable WDM grooming network." 2003. http://www.lib.ncsu.edu/theses/available/etd-02052004-135503/unrestricted/etd.pdf.
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Wang, Ye. "Survivable routing in WDM networks with guaranteed minimum network bandwidth." Thesis, 2007. http://hdl.handle.net/10125/20568.
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Chen, I.-kai, and 陳奕愷. "A Network Engineering Algorithm to Enhance Service Availability in WDM Network." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/96680808242289920979.
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碩士國立高雄第一科技大學
資訊管理研究所
99
Nowadays, the volume requirement of Internet bandwidth is getting huge. To solve the issue in optical networks, Wavelength Division Multiplexing (WDM) is one of the most important technologies. However, two constraints can affect the network performance in terms of blocking probability. One is the wavelength continuity constraint and the other is service availability. In this thesis, we propose a network engineering algorithm to estimate the whole environment of networks. This algorithm wills assignment higher availability resource to link which have heavy load, and hence improve the network performance. The simulation results show that our algorithm can improve blocking probability and link resource utilization in dedicated protection. Further, we can enhance overall service availability without additional resources.
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Sun, Jen-Wei, and 孫仁尉. "Optical Sensor Network and WDM Mesh Network With Self-Healing Function." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/71594271959793855030.
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碩士國立暨南國際大學
電機工程學系
97
In this dissertation, we study of optical sensor network and WDM mesh network with self-healing function. The content related to sensor network includes two sensor networks with self-healing functions, and using time division multiplexing technology and wavelength division multiplexing technology to improve the sensing capacity. The content related to WDM mesh network. We focus on development the mesh network with self-healing functions. All the proposed architecture has self-healing functions that can lead the network back to normal work when there is a link failure. And it can be effective to improve the capacity and reliability.
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Shih, Fu-Yuan, and 施富元. "Study of Fiber Laser in WDM Network Application." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/63114607297868142123.
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碩士元智大學
光電工程研究所
96
In the first part of this thesis, a dual-wavelength erbium-doped fiber compound ring laser using a double-ring filter is demonstrated. By using a ring filter incorporated within the ring cavity, the fiber laser can lase two wavelengths simultaneously. This dual-wavelength output exhibits a good performance having the optical side-mode suppression ratios of 45.3 and 46.3 dB and output powers of ?{8.1 and ?{7.1 dBm, respectively. In the second part, a stable and tunable dual-wavelength EDF ring laser employing a self-injected Fabry-Perot laser diode is demonstrated. By adding an FP-LD incorporated with a tunable bandpass filter within a gain cavity, the fiber laser can lase two wavelengths simultaneously due to the self-injected operation. This dual-wavelength laser has a good performance of the output power and optical side-mode suppression ratio. The laser also shows a wide tuning range from 1523.08 to 1562.26 nm. In the third part, a continuous wave tunable-wavelength fiber laser using self-seeding Fabry-Perot laser diode without optical amplifier inside gain cavity is demonstrated. By employing a tunable bandpass filter and a fiber reflected mirror within a gain cavity, the fiber laser can lase a single-longitudinal wavelength due to the self-seeding operation. This tunable wavelength laser has a good performance of the output power (> ?{15 dBm) and optical side-mode suppression ratio (> 40 dB) in the wavelength tuning range of 1533.75 to 1560.95 nm. Moreover the output stabilities of three kinds of fiber laser are also discussed.
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Peng, Rong-Yu, and 彭榮宇. "Novel Optical Transmitter for WDM Passive Optical Network." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/73725368396702396333.
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碩士國立暨南國際大學
電機工程學系
97
In this dissertation, we study the development of transmitter with fault monitoring function in WDM-PONs. About the development of transmitter, that improves receiver sensitivity by using a VCSEL to amplify the sideband signal and improve the modulation depth. Furthermore, the SSB modulation can be generated. Besides, the proposed scheme benefits from the high reflectivity of the top distributed Bragg reflector mirror of VCSELs to reflect monitoring channels back to optical line terminal for monitoring, the addition of fault monitoring incurs minimal penalty to data transmissions on the networks. These investigations and demonstrations will be useful in the fields of long-distance fiber-wireless systems and WDM-PONs.
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Hung-Jing, Shie. "Guaranteed Quality of Protection (QoP) in WDM Mesh Network." 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0009-0112200611295794.
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郭彥彬. "Real-Time Packet Rescheduling in WDM Ring Access Network." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/33589017414553154699.
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碩士元智大學
資訊工程學系
91
All optical networks have solved the problem of bandwidth insufficiency in the communication network and key technical issue of increasing the transmission speed. The most important technique is Wavelength Division Multiplexing (WDM). It is not only increases the bandwidth of backbone transmission network significantly, but also decreases the network cost and makes the controlling and maintaining of transmission easy. However, it is an important issue to achieve real-time packets quality of service (QoS) on the high speed Internet. This paper uses token to maintain the information of whole Ring Access Network consistent, and it uses the rescheduling algorithm to achieve the QoS of real-time packets. The node only has the token is able to reschedule, while the rest nodes can only transmit, accept, and send information. We adopt the Priority-Differentiated Scheduling (PDS) algorithm to deal with the problem of real-time packets, and allow real-time packets with the high priority to get transmission first to insert the front line of the scheduling unreal-time packets with low priority. This paper combines two algorithms that are used to select wavelength and PDS algorithm to form PEM (PDS-EAC-MTD) algorithm. Within this, the Earliest Available Channel (EAC) algorithm is used for the transmission of real-time packets. It establishes the transmission path for real-time packets. The Minimum Time Difference (MTD) algorithm is used for the transmission of nonreal-time packets to save the channel utilization and let the path of real-time packets establish the path quickly. The simulation results show that as the access nodes and the number of channels are fixed, whereas traffic load and the number of channels are varied, the average delay time resulted from PEM algorithm is shorter than the other three algorithms (NPEM, PEE, and EATS). And when the access nodes are fixed and the number of channels is different, the channel utilization derived from algorithms with MTD is higher than those without MTD.
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Cho, YenTang, and 邱琰唐. "Transmission Scheduling of AAPC in WDM/TDM Ring Network." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/66475331185673382344.
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碩士國立中正大學
資訊工程研究所
90
This thesis considers the problem of scheduling transmissions for All-to-All Personalized Communication(AAPC) in an unidirectional WDM/TDM ring. We assume that each node is equipped with one tunable transmitter and one fixed receiver, tuning time is assumed to be non-negligible. Propagation Delay on transmission was also considered. Our objective is to design a packet schedule which has the minimum schedule length, i.e. duration of AAPC packet transmission period. We formulate this problem as an 0/1 Integer Linear Programming problem. In addition, three heuristic algorithms are proposed to solve this problem. Simulations are performed for 4 to 15 nodes. Performance results show that our heuristic algorithms provide a near-optimal solution comparing with the optimal solution solved by ILP.
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Chia-Hao, Chang, and 張家豪. "The WDM/SCM Based Wireless-over-Fiber Network Architecture." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/02995741511555190780.
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碩士國立交通大學
電信工程系
90
We propose a WDM/SCM wireless-over-fiber network architecture. This architecture combines the advantages of optical WDM/SCM technologies and wireless technologies to construct a simple, high flexibility, robust self-healing functions, more bandwidth efficiency and low cost FTTH network. The proposed WDM/SCM wireless-over-fiber network is a three-level network. In the bottom level many wireless access points (WAPs) are connected as a ring topology, which can avoid the Optical Beat Interference (OBI) problem by a special cascaded add/drop transceiver (CAT) structure. The middle level can perform wavelength selection, wavelength routing and network expanding functions. The top level manages wavelengths transmitted to and from the lower network levels, which can bridge and convert these data format to match the other networks operation. Finally, we present a simple system analysis for our network. Owing to these advantages incur from wireless and optical technologies, the WDM/SCM wireless-over-fiber network that we propose will be a good candidate for the future FTTH system applications.