Orientador: Edson Moschim / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T19:40:07Z (GMT). No. of bitstreams: 1 Dante_ReinaldoGolmia_D.pdf: 5560458 bytes, checksum: a0ff22b15404f7232c1e6c38c9668fdc (MD5) Previous issue date: 2006 / Resumo: Neste trabalho, apresentam-se algumas contribuições para o estudo de redes ópticas inteligentes e transparentes, por exemplo: Redes Ópticas Comutáveis Automaticamente (ASON), no que tange aos protocolos de roteamento e atribuição de comprimentos de onda para o estabelecimento de conexões fim-a-fim em ambientes distribuídos. Os resultados deste trabalho foram obtidos através da simulação dos algoritmos de roteamento e atribuição de comprimentos de onda desenvolvidos em C++. Para que o estudo pudesse ser feito, foram adotadas algumas topologias de rede comerciais e hipotéticas para a comparação de desempenho entre os algoritmos de roteamento e atribuição de comprimentos de onda propostos e os clássicos de modo a identificar as diferenças de comportamento destes algoritmos nas redes ópticas em diversas situações, incluindo as condições de restrição de alcance dos canais ópticos e a continuidade do comprimento de onda no estabelecimento de uma conexão fim-a-fim. Os resultados mostraram que os algoritmos de roteamento e de atribuição de comprimentos de onda propostos são eficientes para o funcionamento destas redes, provendo desempenhos iguais ou superiores em relação aos demais algoritmos de roteamento e atribuição de comprimentos de onda tradicionais medidos em termos da probabilidade de bloqueio dos pedidos de conexão. Como conseqüência, estes algoritmos propostos demonstraram que são capazes de aperfeiçoar o QoS óptico nas redes ópticas inteligentes e transparentes / Abstract: In this work, we present contributions to the routing and wavelength assignment protocols in transparent and intelligent optical networks such as Automatically Switched Optical Networks (ASON) for end-to-end connection establishment on the distributed environments. The results of this work were obtained through simulation of the routing and wavelengh assignment algorithms which were developed in C++. For this study, some commercially and hypothetical network topologies were adopted to compare the performance of the proposed routing and wavelengh assignment algorithms with traditional ones in order to identify the differences of those algorithm performance. Studies were carried out in optical networks under several conditions such as the limit of optical transmission reach and wavelength-continuity constraints for end-to-end connection establishment. The results have shown that the proposed routing and wavelengh assignment algorithms are efficient for use in these networks, providing equal or higher performance than traditional routing and wavelengh assignment algorithms measured in terms of blocking probability of the connection requests. Consequently, the proposed algorithms showed that they are able to improve the optical QoS in transparent and intelligent optical networks / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

Fault localization is the process of realizing the true source of a failure from a set of collected failure notifications. Isolating failure recovery within the network optical domain is necessary to resolve alarm storm problems. The introduction of the monitoring trail (m-trail) has been proven to deliver better performance by employing monitoring resources in a form of optical trails - a monitoring framework that generalizes all the previously reported counterparts. In this dissertation, the m-trail design is explored and a focus is given to the analysis on using m-trails with established lightpaths to achieve fault localization. This process saves network resources by reducing the number of the m-trails required for fault localization and therefore the number of wavelengths used in the network. A novel approach based on Geographic Midpoint Technique, an adapted version of the Chinese Postman’s Problem (CPP) solution and an adapted version of the Traveling Salesman’s Problem (TSP) solution algorithms is introduced. The desirable features of network architectures and the enabling of innovative technologies for delivering future millimeter-waveband (mm-WB) Radio-over-Fiber (RoF) systems for wireless services integrated in a Dense Wavelength Division Multiplexing (DWDM) is proposed in this dissertation. For the conceptual illustration, a DWDM RoF system with channel spacing of 12.5 GHz is considered. The mm-WB Radio Frequency (RF) signal is obtained at each Optical Network Unit (ONU) by simultaneously using optical heterodyning photo detection between two optical carriers. The generated RF modulated signal has a frequency of 12.5 GHz. This RoF system is easy, cost-effective, resistant to laser phase noise and also reduces maintenance needs, in principle. A revision of related RoF network proposals and experiments is also included. A number of models for Passive Optical Networks (PON)/ RoF-PON that combine both innovative and existing ideas along with a number of solutions for m-trail design problem of these models are proposed. The comparison between these models uses the expected survivability function which proved that these models are liable to be implemented in the new and existing PON/ RoF-PON systems. This dissertation is followed by recommendation of possible directions for future research in this area.

Orientador: Nelson Luis Saldanha da Fonseca / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-27T20:17:10Z (GMT). No. of bitstreams: 1 Moura_PedroMesquita_M.pdf: 2113385 bytes, checksum: 1ba529be35f0f2fbcb95f91c01acfa29 (MD5) Previous issue date: 2015 / Resumo: As redes ópticas com multiplexação por comprimento de onda empregam uma grade fixa de divisão do espectro, dividindo-o em grandes faixas com alta capacidade de transmissão. Apesar de este esquema atingir altas velocidades de até 100Gb/s atualmente, a demanda de tráfego está cada vez maior e novas soluções são propostas como futuro das redes ópticas. A divisão do espectro em grandes faixas pode gerar problemas de falta de flexibilidade, onde requisições com baixas demandas de tráfego subutilizam comprimentos de onda. Nesse contexto as redes ópticas elásticas emergem, buscando flexibilizar a alocação do espectro utilizando alta granularidade na divisão do espectro, de modo que as conexões utilizem tipicamente vários slots, que são a unidade de alocação de redes ópticas elásticas. Utilizando-se da tecnologia de Multiplexação por Divisão de Frequências Ortogonais (OFDM), é possível fazer com que os slots adjacentes se sobreponham ortogonalmente, sem interferência, atingindo alta eficiência de utilização do espectro. O roteamento e alocação de espectro surge neste contexto com o objetivo de alocar rotas nas redes ópticas elásticas, necessitando caminhos na rede que possuam espectro suficiente para acomodar a demanda de tráfego, e a fim de manter o sinal no domínio óptico e evitar a custosa operação de conversão opto eletrônica, é necessário manter a mesma porção do espectro alocada em todos os enlaces do caminho, problema denominado de restrição de continuidade do espectro. Os slots devem ser também adjacentes para que estes se sobreponham utilizando OFDM, problema chamado de restrição de contiguidade do espectro. Esta dissertação investiga o problema roteamento e alocação de espectro e propõe algoritmos que melhoram características da rede, como qualidade de serviço, custo operacional e eficiência energética / Abstract: Wavelength division multiplexing optical networks employ fixed grid for spectrum, with high capacity transmission slots. Although this division allows high speeds of up to 100Gbps nowadays, the traffic demand grows each year and new solutions are needed in optical networks. The high capacity fixed grid can produce problems like the sub utilization of wavelengths by requests with lower traffic demand than their capacity. In this context the elastic optical networks emerged, allowing flexible division of spectrum, in a way that connections allocate several slots, the unit of spectrum of elastic optical networks. Together with Orthogonal Frequency Division Multiplexing (OFDM), it is possible to orthogonally overlap adjacent slots, without interference, achieving higher spectrum efficiency. The routing and spectrum assignment problem aims to allocate routes and spectrum in elastic optical networks, finding for paths with enough spectrum to accommodate the traffic demand. In order to avoid the costly optoelectronic signal conversion, it is necessary to allocate the same portion of spectrum in each link of the path, problem called spectrum continuity constraint. The slots must also be allocated contiguously, in order to the overlapping with OFDM be effective, problem called spectrum contiguity constraint. This work investigate the routing and spectrum assignment problem and proposes algorithms to improve network characteristics such as quality of service, operational expenditure and energy efficiency / Mestrado / Ciência da Computação / Mestre em Ciência da Computação

The energy consumption of communication networks is continuously growing. Many energy saving approaches have been proposed at the device, system, and network level. The most promising way to address this problem is to utilize photonic technologies as much as possible thanks to their low energy consumption per bit performance. Moreover, several approaches have been proposed to further reduce the energy consumption in optical networks. One popular technique exploits low power modes (e.g., sleep or doze mode) for devices that are not used. However, sleep mode based approaches may affect the way optical connections (i.e., lightpaths) are routed, or alter the characteristics of some devices. This in turn may have a detrimental impact on crucial network/device performance parameters. In other words a green approach may introduce additional delay, change the level of resource utilization in the network, or even impact the lifetime of a device, resulting in increased network operational cost. This thesis provides a study that carefully assesses, in both access and core networks, the trade-off between the benefits of sleep-based energy-efficient schemes and their possible side-effects. In fiber access networks putting a device into sleep mode and waking it up can introduce a significant energy overhead. Already proposed energy-efficient approaches reduce this overhead by aggregating as much as possible the traffic before a transmission. However, aggregating data may cause an additional delay that in some cases might not be acceptable. This thesis investigates the trade-off between energy saving and additional packet delay in the case of a LTE backhaul network based on wavelength division multiplexing passive optical network (WDM-PON). The thesis proposes a novel energy-efficient approach based on the dozing concept able to precisely control when a transmitter needs to wake up in order to maximize the time spent in sleep mode, while assuring that packet transmissions are completed before a given deadline. The proposed scheme is also able to exploit possibly diverse traffic delay requirements to further improve energy saving performance. In optical core networks, one way to decrease the energy consumption is to minimize the number of used active devices by aggregating the lightpaths on the lowest possible number of active fiber links. Routing strategies based on this intuition are beneficial in terms of energy saving, but on the other hand may impact the network performance (e.g., blocking probability) by affecting length of the lightpaths and link occupancy distribution. This trade-off is evaluated in the thesis with the help of a specially designed routing and wavelength assignment (RWA) strategy referred to as weighted power aware lightpath routing (WPA-LR). The WPA-LR strategy permits the fine tuning between the minimization of two objectives: energy consumption and network resource (i.e., wavelength) utilization. Evaluation results confirm that energy efficiency and network performance are conflicting objectives. However, the proposed WPA-LR strategy offers energy minimization with acceptable impact on the network performance. The thesis also investigates the impact that sleep-based energy-efficient strategies have on the lifetime of a number of optical network devices, in both access and core networks. In fact, utilizing a sleep mode functionality may change the operational conditions of the device which can impact the device lifetime. This is a crucial aspect to consider because it may directly affect the network operational cost related to fault management. The thesis provides a methodology to assess under which conditions and for which devices an energy-efficient scheme may lead to overall cost benefit vs. a (possible) increase of reparation cost. It was found that in access networks and with business customers a small lifetime variation in optical line terminals (OLTs) or in optical network units (ONUs) can lead to significant cost increase that cannot be covered by the profits coming from the energy saving. In core networks erbium doped fiber amplifiers (EDFAs) are the most vulnerable devices in terms of impact on their lifetime. For this reason it was found that the usage of green routing algorithms based on putting EDFAs into sleep mode may not always be economically beneficial. In conclusion this thesis provides a different perspective on sleep mode based energy-efficient algorithms where the potential benefit in terms of energy saving is weighted against the impact of a possible degradation of the network performance and devices lifetime. On the other hand these performance degradations can be controlled and limited by the proposed algorithms. / Energikonsumtionen av kommunikationsnätverk, växer kontinuerligt. Många energibesparande åtgärder har föreslagits, såväl på komponentnivå, systemnivå och nätverksnivå. Det mest lovande sättet att hantera energibehov i kommunikationsnätverk är att utnyttja optisk teknologi så mycket som möjligt då denna har potential att ge låg energiförbrukning per bit. Det finns också ett antal föreslagna metoder för att ytterligare reducera energibehovet i optiska nätverk. En av de mest använda teknikerna bygger på att låta enheter som ej används gå ner på låg effekt (”sovläge”). Om detta används i allt för hög utsträckning kan det dock påverka hur optiska förbindelser (sk lightpaths) sätts upp eller ge förändrade egenskaper hos de aktuella komponenterna. Detta kan i sin tur ha en skadlig inverkan på de centrala nätverks- och komponentegenskaper vilket påverkar prestandan. Med andra ord kan en sådan ”grön” ansats baserad på sovläge leda till ökad fördröjning, förändring av resursutnyttjandet i nätet och till och med påverka risken för att det uppstår fel i komponenterna vilket ökar driftskostnaden för nätet. Denna avhandling fokuserar på dessa aspekter och visar upp resultat som belyser avvägningen mellan sovlägesbaserade energieffektiva strategier och deras eventuella bieffekter. Att slå av och väcka upp komponenter i optiska access-nätverk kan vara förknippat med en signifikant extra energikostnad. Tidigare föreslagna energieffektiva strategier försöker reducera denna ökade energikostnad genom att samla så mycket trafik som möjligt innan överföringen sker. Dock kan detta leda till ökad fördröjning som i vissa lägen inte är acceptabel. I avhandlingen undersöker vi avvägningen mellan energibesparingar och ökad paketfördröjning i fallet med LTE distributionsnät baserade på våglängsmultiplexerade passiva optiska nätverk (WDM-PON). Vi föreslår en ny energieffektiv ansats baserad på att enheter försätts i ”slummer-läge”. Detta gör det möjligt att med god precision bestämma när en sändare behöver väckas upp i syfte att maximera tiden i sovläget och att försäkra sig om att paketen kommer fram inom avsedd tid. Strategin är även kapabel att utnyttja differentierad fördröjning för att ytterligare förbättra energibesparingen. Ett sätt att minska energikonsumtionen i optiska distributionsnät är att minimera antalet aktiva enheter genom att exempelvis samla optiska förbindelser till ett minimalt antal aktiva fiberlänkar. Routingstrategier som utgår från denna princip är fördelaktiga ur energisynpunkt men kan å andra sidan skada nätverksprestanda (exempelvis blockeringssannolikhet) genom påverkan på förbindelselängder och annorlunda belastning av länkarna. Denna avvägning utvärderas i avhandlingen med hjälp av en specifikt utformad strategi för routing och våglängstilldelning (RWA) som vi benämner ”viktad effektmedveten optisk förbindelserouting” (WPA-LR). Denna strategi möjliggör noggrann avvägning mellan minimeringen av två kriterier: å ena sidan energikonsumtion, å andra sidan utnyttjandet av nätverksresurser (speciellt väglängdsutnyttjandet). Vår utvärdering bekräftar att energieffektivitet och nätverksprestanda står i motsatsförhållande till varandra. Dock erbjuder WPA-LR strategin minimering av energin med en acceptabel påverkan på nätverksprestanda. Slutligen undersöks i avhandlingen den påverkan som sovlägesbaserade energieffektiva strategier har på livslängden för optiska nätverkskomponenter, både i access- och i distributionsnät. Användning av sovlägesfunktion kan påverka arbetsförhållandena för en komponent, något som i sin tur kan påverka livslängden. Detta är en kritisk aspekt att ta i beaktande då det direkt kan påverka driftskostnaden kopplad till nätunderhållet. En metod ges för att utvärdera under vilka förhållanden och för vilka enheter en energieffektiv strategi kan leda till en total kostnadsfördel jämfört med en (möjlig) ökning av reparationskostnaderna. Ett resultat är att, i accessnät och för företagsanvändare, så kan även en liten variation i feluppkomst i optiska linjeterminaler (OLTs) eller optiska nätverksenheter (ONUs) leda till signifikanta kostnadsförluster vilka inte kan kompenseras genom de vinster som kan åstadkommas med energibesparingar. I distributionsnät är erbium-dopade fiberförstärkare (EDFAs) de mest utsatta enheterna vad gäller inverkan på livslängd. Genom att studera routingstrategier (ex.vis WPA-LR) har vi funnit att användningen av ”gröna” routingalgoritmer baserade på att lägga EDFAs i sovläge inte alltid är ekonomiskt fördelaktigt. Denna avhandling ger ett perspektiv på sovlägesbaserade energieffektiviseringsalgoritmer där de potentiella fördelarna vad gäller minskade driftskostnader ställs mot möjliga försämringar av nätverksprestanda och komponenters livslängd. Å andra sidan kan dessa försämringar hållas under kontroll och begränsas av den föreslagna algoritmen. / La consommation d'énergie des réseaux de communication ne cesse de croître. Ce problème fait l’objet de nombreuses approches orientées vers les économies d'énergie (écoénergétiques) au niveau des appareils (équipements) des systèmes et des réseaux. La façon la plus prometteuse de limiter l’augmentation de consommation évoquée est d'utiliser autant que possible des technologies photoniques, vu leur faible consommation d'énergie par bit. Plusieurs autres approches ont été proposées pour réduire davantage encore la consommation d'énergie dans des réseaux optiques. Une technique populaire exploite les modes de faible puissance (par exemple le mode veille) pour les appareils qui ne sont pas utilisés. Cependant, les approches basées sur le mode de veille peuvent affecter la manière dont les liaisons optiques (circuits optiques) sont acheminées, ou modifier les caractéristiques de certains appareils. Cela peut avoir un impact négatif sur les paramètres de performance des réseaux/équipements cruciaux. En d'autres termes, une approche écoénergétique peut introduire un retard supplémentaire, changer le niveau d'utilisation des ressources dans le réseau, ou même avoir un impact sur le taux d'échec d'un équipement, entraînant une augmentation des coûts d'exploitation du réseau. Cette thèse évalue attentivement, à la fois dans le réseau d'accès mais aussi dans le cœur du réseau, le compromis entre les avantages des régimes économes en énergie utilisant le mode veille et leurs effets secondaires possibles. Dans les réseaux d'accès optiques, mettre un équipement en mode veille et le réactiver peut introduire une surcharge d'énergie significative. Les approches d'économie d'énergie déjà proposées réduisent cette surcharge en regroupant autant que possible le trafic avant sa transmission. Toutefois, les données d'agrégation peuvent provoquer un retard supplémentaire qui peut ne pas être acceptable dans certains cas. Cette thèse étudie le compromis entre les économies d'énergie et un retard supplémentaire des paquets dans le cas d'un réseau backhaul LTE basé sur réseau optique passif à multiplexage en longueur d'onde (WDM-PON). La thèse propose une nouvelle approche éco énergétique. Elle développe un concept au travers duquel il est possible de contrôler avec précision quand un émetteur doit se réactiver, afin de maximiser le temps passé en mode veille tout en veillant à ce que les transmissions de paquets soient terminées en temps voulu. Le schéma proposé est également capable d’exploiter les (éventuelles) exigences diverses de retard de trafic pour améliorer encore les économies d'énergie. Dans le cœur des réseaux optiques, on peut diminuer la consommation d'énergie en minimisant le nombre d’équipements actifs utilisés pour l’acheminement des circuits optiques et le nombre de liens actifs à fibres optiques. Les stratégies de routage basées sur ce principe sont bénéfiques en termes d'économie d'énergie, mais peuvent affecter les performances du réseau (par exemple, la probabilité de blocage) en affectant la longueur des circuits optiques et la distribution d’occupation des liens. Ce compromis est évalué dans la thèse avec l'aide d’une stratégie de routage et affectation de longueur d'onde (RWA) appelée routage des circuits optiques conscient de la puissance (WPA-LR). La stratégie WPA-LR permet le réglage fin entre deux objectifs: minimiser la consommation d'énergie et minimiser l’utilisation des ressources réseau (i.e. longueur d'onde). Les résultats de l'évaluation confirment que l'efficacité énergétique et les performances du réseau ont des objectifs contradictoires. Cependant, la stratégie WPA-LR proposée permet la minimisation de l'énergie avec un impact acceptable sur les performances du réseau. La thèse étudie également l'impact que les stratégies d’économie d’énergie basées sur le mode veille ont sur la durée de vie d'un certain nombre d’équipements de réseau optique, dans les deux réseaux d'accès et de base. L'utilisation du mode veille peut en effet modifier les conditions de fonctionnement de l’équipement, ce qui peut influer sur la durée de vie de l'appareil. Ceci est un aspect crucial à considérer, car il peut affecter directement le coût opérationnel du réseau lié à la gestion des pannes. La thèse propose une méthodologie pour évaluer dans quelles conditions et pour quels dispositifs un système économe en énergie peut conduire à des avantages de coûts globaux par rapport à une (possible) augmentation des coûts de maintenance. Dans les réseaux d'accès et auprès de clients commerciaux, il a été constaté qu’une petite variation de taux d'échec dans les terminaux de ligne optique (OLT) ou dans les unités de terminaison de réseau optique (ONUs) peut conduire à des pertes financières importantes qui ne peuvent être compensées par les bénéfices provenant des économies d'énergie. Dans les cœurs de réseaux les amplificateurs à fibre dopée en erbium (EDFA) sont les équipements les plus vulnérables en termes d'impact sur leur durée de vie. Pour cette raison, l'utilisation d'algorithmes de routage écoénergétiques basé sur la mise en mode veille des EDFA peut par conséquent n’être pas toujours économiquement avantageuse. En conclusion, cette thèse fournit une perspective différente sur des algorithmes économes en énergie basés sur l’utilisation du mode veille. Leur bénéfice potentiel en termes d'économie d'énergie est comparé à l'impact d'une éventuelle dégradation d’une part de la performance du réseau et d’autre part de la durée de vie des équipements. Ces dégradations de performances peuvent être contrôlées et limitées par les algorithmes proposés. / Zużycie energii elektrycznej w sieciach komunikacyjnych stale rośnie. Do tej pory zostało zaproponowanych wiele metod oszczędzania energii na poziomie urządzeń, systemów i sieci. Najbardziej obiecującym podejściem do tego problemu jest wykorzystanie technologii optycznych, z uwagi na ich niskie zużycie energii „per bit”. Ponadto wiele różnych metod przeznaczonych dla sieci optycznych zostało przedstawionych w literaturze. Jedna z popularnych technik wykorzystuje tryb niskiego poboru energii (uśpienia) w urządzeniach, które nie są używane. Jednakże techniki wykorzystujące tryb uśpienia mogą mieć wpływ na kierowanie optycznych połączeń sieciowych (lightpaths) lub zmieniać właściwości urządzeń. Natomiast to może mieć negatywny wpływ na kluczowe parametry wydajności sieci czy urządzeń sieciowych. Innymi słowy algorytmy oszczędzające energię mogą wprowadzić dodatkowe opóźnienia, zmienić wykorzystanie zasobów sieciowych, a nawet wpływać na awaryjność urządzeń zwiekszając tym samym koszt eksploatacji sieci. Praca ta przedstawia i analizuje kompromis pomiędzy korzyściami płynącymi z energooszczędnych algorytmów opartych na trybie uśpienia, a ich ewentualnymi skutkami ubocznymi, zarówno w sieciach dostępowych, jak i szkieletowych. W przypadku optycznych sieci dostępowych proces wprowadzenia urządzenia w tryb uśpienia i jego wybudzenia może spowodować znaczący narzut energetyczny. Proponowane sposoby zmniejszenia tego narzutu agregują ruch sieciowy przed jego transmisją, Jednakże taka agregacja powoduje dodatkowe opóźnienia transmisji, które w niektórych przypadkach mogą być niedopuszczalne. Praca ta analizuje kompromis pomiędzy oszczędzaniem energii, a dodatkowymi opóźnieniami transmisji w przypadku sieci LTE-backhaul, bazowanej na technologii pasywnych sieci optycznych, opartych na multipleksowaniu z podziałem długości fali WDM-PON (Wavelength Division Multiplexing Passive Optical Network). Niniejsza praca proponuje nowatorską metodę oszczędzania energii, opartą na koncepcji drzemki (dozing), która precyzyjnie kontroluje czas wybudzania nadajnika, tak aby zmaksymalizować czas spędzony w trybie drzemki, przy zapewnieniu, że transmisja danych zostanie zakończona przed upływem wymaganego czasu. Proponowana metoda wykorzystuje również zróżnicowane wymagania maksymalnych opóźnień transmitowanych danych do dalszej poprawy wydajności energetycznej. Jednym ze sposobów zmniejszania zużycia energii w światłowodowych sieciach szkieletowych jest zredukowanie liczby aktywnych urządzeń, poprzez umiejętne kierowanie optycznych połączeń sieciowych przy użyciu już aktywnych łączy światłowodowych. Kierowanie ruchu sieciowego oparte na tym pomyśle jest korzystne z punktu widzenia oszczędzania energii, choć z drugiej strony może mieć wpływ na parametry wydajnościowe sieci (np. zwiększenie prawdopodobieństwa blokady połączeń) poprzez oddziaływanie na długość połączeń, czy zajętość łączy. Przytoczony problem jest analizowany w tej pracy za pomocą specjalnie zaprojektowanego algorytmu routingu i przypisania długości fali RWA (Routing and Wavelength Assignement), nazwanego WPA-LR (Weighted Power Aware Lightpath Routing). Algorytm WPA-LR pozwala na precyzyjną regulację pomiędzy redukcją zużycia energii i optymalizacją wykorzystania zasobów sieciowych. Wyniki wykonanej analizy problemu potwierdzają, że efektywność energetyczna i wydajność sieci to cele ze sobą sprzeczne. Jednakże proponowana strategia (WPA-LR) umożliwia kontrolę i osiągnięcie kompromisu pomiędzy zmniejszeniem zużycia energii, a pogorszeniem wydajności sieci. Praca ta bada również wpływ energooszczędnych strategii, opartych o tryb uśpienia, na trwałość optycznych urządzeń sieciowych, zarówno w sieciach dostępowych, jak i szkieletowych. Używanie trybu uśpienia może zmienić warunki pracy urządzenia, które z kolei mogą mieć wpływ na jego trwałość. Natomiast zmniejszenie trwałości urządzenia może bezpośrednio oddziaływać na koszt eksploatacji sieci związany z zarządzaniem awariami. Niniejsza praca proponuje metodologię oceny, na jakich warunkach i w przypadku których urządzeń, używanie algorytmów oszczędzania energii może prowadzić do ogólnych korzyści finansowych lub strat związanych ze wzrostem kosztu eksploatacji sieci. W pracy stwierdzono, że w sieciach dostępowych, w szczególności obsługujących klientów biznesowych, mały wpływ na awaryjność optycznych terminali ONU (Optical Network Unit) lub optycznych urządzeń dystrybucyjnych OLT (Optical Line Terminal) może prowadzić do znacznego zwiększenia kosztów, które mogą przekroczyć zyski związane z oszczędzaniem energii. W sieciach szkieletowych wzmacniacze światłowodowe EDFA (Erbium Doped Fiber Amplifier) są najbardziej wrażliwymi urządzeniami pod względem wpływu na ich awaryjność. W pracy dowiedziono, że użycie energooszczędnych algorytmów kierowania połączeń światłowodowych, opartych na wprowadzaniu EDFA w tryb uśpienia, nie zawsze jest korzystne ekonomicznie. Niniejsza praca przedstawia nowatorskie spojrzenie na energooszczędne algorytmy oparte na wprowadzaniu urządzeń w tryb uśpienia, gdzie potencjalne korzyści w zakresie oszczędzania energii są porównane ze stratami związanymi z degradacją wydajności sieci lub żywotności urządzeń sieciowych. / <p>QC 20160509</p>

O presente trabalho trata das estratégias de agregação de tráfego IP nas redes óticas WDM. Utilizar todo um comprimento de onda para transportar um único fluxo de dados numa rede WDM é ineficiente. O problema conhecido como agregação de tráfego consiste na multiplexação de distintos fluxos de tráfego em um mesmo comprimento de onda sobre um caminho ótico. A alocação de múltiplos fluxos de tráfego em comprimentos de onda é realizada por protocolos de controle de admissão, roteamento e designação de comprimento de onda (RWA) e algoritmos de agregação de tráfego. Neste trabalho é simulado o comportamento dinâmico e elástico do tráfego IP diretamente sobre a camada ótica. Com base nos resultados das simulações determinam-se os efeitos da granularidade dos fluxos IP nos parâmetros de desempenho da rede. As topologias utilizadas durante as simulações são das redes NSFNET e Kyatera. É estabelecida também uma correlação entre a granularidade dos fluxos de tráfego e os parâmetros de desempenho da rede. / The present work covers the IP traffic grooming strategies in optical WDM networks. Using an entire wavelength to transport an individual traffic flow in a WDM network is inefficient. The problem known as traffic grooming consists in the multiplexing of different traffic flows in a single wavelength within a lightpath. The allocation of multiple traffic flows is performed by routing and wavelength assignment (RWA) and traffic grooming algorithms. In this work it is simulated the dynamic and elastic behavior of IP traffic directly on top of the optical layer. Based on the simulation results the effects of the IP traffic flow granularity on the network performance parameters are determined. The simulated topologies are the NSFNET and Kyatera. It is also established the correlation between the traffic flow granularity and the network performance parameters.

Centralized light source (CLS) at the central office is an attractive solution for low-cost implementation of WDM-PON, as it eliminates the need of wavelength-specific transmitters and wavelength management at the optical network units (ONU). CLS can be realized by either a carrier-distributed scheme or a remodulation scheme. In both schemes, however, the upstream signal is susceptible to the interferometric crosstalk induced by the beating between the upstream signal and the back-reflected light due to the intrinsic Rayleigh Backscattering (RB), both of which are of the same wavelength. We propose and demonstrate a simple and novel scheme to suppress the RB noise in the carrier-distributed WDM-PON. Differential phase-shift keying (DPSK) is used as the upstream modulation format and the destructive port of the delay-interferometer (DI) is employed to demodulate the upstream DPSK signal. As the spectrum of RB towards the OLT is narrow due to the very narrow spectrum of the distributed carrier, the RB noise can be considerably rejected by the notch filter-like destructive port of the DI at the OLT, which is used simultaneously to demodulate the upstream DPSK signal. The scheme can also be extended to the application in the remodulation-based WDM-PON, as long as the downstream signal has a narrow spectrum (i.e. via reducing downstream modulation depth). A unique feature of the DPSK signal with reduced modulation depth (RMD-DPSK) is that it can be demodulated by DI's destructive port without extinction ratio (ER) degradation, whereas the demodulated signal from DI's destructive port has a very low ER and can be used as the source for upstream remodulation. We also proposed a novel offset-Manchester coding to suppress Rayleigh noise in electrical domain via a postdetection high-pass filter. / Foreseeing the rapidly growing demand for multimedia services and the trend of service convergence, the penetration of optical fiber in access network is an ultimate solution to break the last-mile bottleneck imposed by the 100-year-old copper network. One of the most promising solutions to realize optical access is the passive optical network (PON), in which the network infrastructure is shared by many subscribers and has no active elements between the central office and the customer. Thus a PON requires neither electrical power nor active management, leading to effective reduction in operational expenses. Time-division-multiplexed passive optical networks (TDM-PONs) such as Ethernet PON (EPON) and Gigabit PON (GPON) are being widely deployed in current fiber-based access networks for providing broadband access, offering triple-play services including video, data and voice. In the near future, wavelength-division-multiplexed passive optical network (WDM-PON) can be the enabler of the next-generation optical broadband access that requires large dedicated and symmetric bandwidth, data privacy, and upgrade flexibility. TDM-PONs also can benefit from WDM technologies for capacity upgrade. / With more diverse multimedia and data services available for broadband access, the access network has to be flexible enough to cope with various data or video delivery such as broadcast/multicast services, in addition to the point-to-point traffic. Multicast is more attractive, compared to broadcast, as it allows selective control of the connection for each subscriber individually. Multicast can be easily realized in TDM-PONs as it employs power-splitting at the remote node (RN). However, it is more challenging in WDM-PONs, due to the dedicated connection between the optical line terminal (OLT) and each ONU. Many studies have been carried out to solve this problem. The prior schemes either need relatively complicated multicast control and/or cannot support future proof 10-Gb/s symmetric point-to-point (PtP) transmission. We proposed a novel multicast control scheme for a WDM-PON with 10-Gb/s symmetric bit rate. The multicast data encoded in DPSK format is superimposed onto all PtP channels modulated in inverse return-to-zero format. With an athermal Dr being used at the ONU to demodulate the DPSK signal, the multicast data can be effectively disabled by slight detuning the laser wavelength at OLT, which has negligible effect on the PtP data. The proposed scheme differs from all the previous schemes in that, the multicast control is realized via the inherent wavelength management of WDM systems, rather than via any other additional adjustment such as ER, synchronization, and polarization. v / Xu, Jing. / Adviser: Lian-Kuan Chen. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

In this thesis, a fully millimetre-wave (mm-wave) generation and transmission system is proposed for futuristic communications. Significant challenges have been dealt with regarding the proposed system, including designing the mm-wave generation and transmission technique, and its application in cellular networks. These challenges are presented through five main contributions and validated via Optiwave Design Software and MATLAB simulation tools. Firstly, three novel photonic generation methods are proposed and designed based on the characteristics of Brillouin fibre laser and the Stimulated Brillouin Scattering (SBS) effects with phase modulation. The mm-wave carriers are successfully generated with a tuning capability from 5 to 90 GHz. Also, these carriers are with good Signal to Noise Ratio (SNR) up to 51 dB, and low noise signal power of about -40 dBm. The impact of these methods is obtaining stable mm-waves appropriate for Radio over Fibre (RoF) transmission systems in 5G optical networks. Secondly, a full-duplex RoF system with the generation of a 64 GHz mm-wave is proposed. Successful transmission of the mm-wave over a fibre link is achieved for up to 100 km of fibre with a data rate of 5 Gbits/s. The main impact of this system is cost reduction and performance improvement by simplifying mm-wave generation and transmission over fibre. Also, it ensures a useful communication link for small cell networks. Thirdly, a hybrid Fibre/Free-space optical (FSO) system for the generation and transmission of 64 GHz mm-wave is proposed. This optical system provides a low latency communication link and overcomes mm-wave high path losses. A successful mm-wave transmission is achieved over a 10 km fibre length, and 2 km FSO link length with a good Bit Error Rate (BER) of about 1.5×10-13 and a data rate of 10 Gbits/s. This system increases the network coverage area by transmitting the mm-wave over the FSO link to the areas with natural obstacles the laying of fibre cables impossible. Also, it can be used as an effective solution under emergency disaster conditions. Fourthly, a comprehensive study of the wireless propagation performance for different mm-wave bands (28, 60, and 73 GHz) as cellular networks is investigated and compared with the 2.4 GHz Ultra-High Frequency band (UHF). A map-based scenario is proposed for the deployment of Base Stations (BSs) within the Brunel University London Campus map to consider real blockage effects. This investigation involved specifying which mm-wave spectrum can enhance the futuristic cellular networks, by evaluating the coverage and rate trends. Comparative results show that the 73 GHz bands can achieve the higher rate with good coverage and the lowest interference effects than the other mm-wave bands. Finally, a simplified path loss model is proposed to estimate precisely the 28 GHz mm-wave performance, which is considered a key component in 5G networks in outdoor applications. The proposed path loss model captures the diffraction and specular reflection impacts on mm-wave wireless propagation.

Besides colorless ONUs, we investigate potentially low cost, high speed vertical-cavity-surface-emitting lasers (VCSELs) for use in future access networks. VCSELs are attractive because they may meet the stringent size, power dissipation and cost constraints of access network components. We carry out experiments to demonstrate that up to 20 Gb/s direct modulation of long wavelength VCSEL is possible and evaluate their performance as high-speed transceivers. / In order to reduce the complexity and costs of ONU transceiver, we propose a scheme based on a nonreciprocal optical modulator and a linear loop mirror for receiving downstream and sending upstream data We show that the nonreciprocity of traveling wave electrodes can selectively impress signal modulation onto the reflected upstream signals only. Monolithic integrated transceivers may thus remodulate downstream signals for upstream data transmission without needing integrated optical circulators. The proposed ONU is thus compatible with monolithic integration. / In this thesis, we describe our research on photonic devices and subsystems for future access networks. Since optical network units (ONUs) are the most cost-sensitive parts, we first investigate the use of advanced modulation format in colorless ONU structure. We implement a scheme which uses dark return-to-zero (DRZ) for downstream transmission and remodulation of it using a differential-phase-shift-keying (DPSK) for upstream both at 10 Gb/s. We also experimentally demonstrate silicon microring based optical frequency discriminators for use in demodulating DPSK and differential-quadrature-phase-shift-keying (DQPSK) signals. We show that the scheme is robust to variations in bit-rates in contrast with conventional Mach-Zehnder delay interferometer scheme. / Internet traffic has undergone tremendous growth in the past decades and has already penetrated into the daily lives of the general population. Demand for new high bandwidth services is beginning to drive the deployment of optical fiber-based access networks to solve the so-called last mile bottleneck around the world. Passive optical networks (PON) are attractive because there are no active components in the transmission line, thus reducing operational and deployment costs. Time-division-multiplexing (TDM) used in currently deployed PON, in which the bandwidth is shared among the users by time domain multiplexing, does not fully utilize the bandwidth potential of optical fibers and will not be able to satisfy the bandwidth demand in access networks in the near future. Among the advanced multiplexing techniques, wavelength-division-multiplexing (WDM) PON is a good candidate technology for providing sustained bit-rates beyond 10 Gb/s in access networks. However, reduction of costs in WDM PON remains a key challenge for their practical deployment. / Wired and wireless hybrid optical access networks are also investigated. Radio-over-fiber is one low-cost approach to deliver broadband wireless services, in which radio signals at the carrier frequency are delivered over optical networks from a central office to remote antenna base stations. Generation of high frequency carrier and radio frequency fading are the main research challenges. We propose and demonstrate frequency upconversion based on frequency doubling and quadrupling. Novel wired and wireless hybrid subsystems that mitigate millimeter-wave signal distortion are also demonstrated. / Xu, Lin. / Adviser: H. K. Tsang. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

O presente trabalho trata das estratégias de agregação de tráfego IP nas redes óticas WDM. Utilizar todo um comprimento de onda para transportar um único fluxo de dados numa rede WDM é ineficiente. O problema conhecido como agregação de tráfego consiste na multiplexação de distintos fluxos de tráfego em um mesmo comprimento de onda sobre um caminho ótico. A alocação de múltiplos fluxos de tráfego em comprimentos de onda é realizada por protocolos de controle de admissão, roteamento e designação de comprimento de onda (RWA) e algoritmos de agregação de tráfego. Neste trabalho é simulado o comportamento dinâmico e elástico do tráfego IP diretamente sobre a camada ótica. Com base nos resultados das simulações determinam-se os efeitos da granularidade dos fluxos IP nos parâmetros de desempenho da rede. As topologias utilizadas durante as simulações são das redes NSFNET e Kyatera. É estabelecida também uma correlação entre a granularidade dos fluxos de tráfego e os parâmetros de desempenho da rede. / The present work covers the IP traffic grooming strategies in optical WDM networks. Using an entire wavelength to transport an individual traffic flow in a WDM network is inefficient. The problem known as traffic grooming consists in the multiplexing of different traffic flows in a single wavelength within a lightpath. The allocation of multiple traffic flows is performed by routing and wavelength assignment (RWA) and traffic grooming algorithms. In this work it is simulated the dynamic and elastic behavior of IP traffic directly on top of the optical layer. Based on the simulation results the effects of the IP traffic flow granularity on the network performance parameters are determined. The simulated topologies are the NSFNET and Kyatera. It is also established the correlation between the traffic flow granularity and the network performance parameters.

[pt] A indústria das comunicações tem passado nos últimos anos, mundialmente, por profundas transformações. A Internet é a responsável pela maior destas transformações. Com o advento da Internet, existe a necessidade de uma banda de transmissão maior para o tráfego de dados. Para resolver esse problema, surgiu o conceito de redes ópticas e a multiplexação no domínio do comprimento de onda. Entretanto, isso criou um outro problema: o roteamento dos pacotes. A maior parte das redes de comunicação hoje em dia, ainda possui muitos sinais eletrônicos, o que significa que os sinais ópticos precisam ser convertidos em elétricos para serem ampliados, regenerados ou roteados e, depois, reconvertidos para ópticos. Isso acaba gerando atrasos na transmissão dos sinais e um gargalo nas redes ópticas. Para minimizar este problema, vários algoritmos foram criados. Apegando-se a tais fatos, este estudo explora o tema para implementar um algoritmo de enumeração recursiva, que tem como objetivo alocação de comprimentos em redes ópticas, visando minimizar o custo total de transmissão. Esse algoritmo foi testado e comparado com o algoritmo de programação linear, que fornece a solução ótima. / [en] The communication industry was passing in lastest years by great transformations in world. Internet is the mainly responsable for that, because there is the necessity of a large band to data transmission. The optical networks concept and wavelength division multiplexing technology were arised in order to solve this problem. However, this created another problem: the packet routing. The major part of communications networks still has electronics signals. This means that the optical signals have to be converted into electrical signals to be amplified, regenerated and routed and later recovered into optical. This implies in a delay on the data transmission and creates a bottleneck in the optical networks. Some algorithms have been created to minimize this problem. This dissertation has tried to develop an algorithm to solve RWA (routing and wavelength assignment) problems, aiming at the minimum total cost to transmitt datas. This algorithm was tested and compared with the linear program algorithm that gives the optimal solution to RWA problem.