Este trabalho apresenta uma análise sobre a Arquitetutra PCE (Path Computation Element), como alternativa para o roteamento inter-domínios em redes heterogêneas, ou seja, em ambientes onde ocorre a integração do domínio óptico, das redes de transporte ópticas, com o domínio eletrônico, das redes convencionais, tratando inclusive com questões de qualidade de transmissão do sinal óptico, ou QoT (Quality of Transmission). Os objetivos e o funcionamento do mecanismo do PCE em redes integradas são detalhados. São apresentados também os conceitos e definições das redes ópticas, bem como seus principais elementos, a proposta de interconexão das mesmas com as redes convencionais provendo uma rede única e integrada, o papel dos planos de controle, e os principais mecanismos de roteamento. A análise do PCE foi direcionada para o comportamento do principal protocolo utilizado na sua arquitetura, denominado PCE Protocol. De forma mais específica, foi realizada a análise de suas mensagens de requisição de rotas e das mensagens de respostas a estas requisições, e sua interferência no tráfego dos enlaces das redes onde são introduzidas. A partir daí é apresentada uma proposta de extensão de parâmetros para o protocolo PCE Protocol, com o objetivo de atender necessidades específicas de QoT, baseado em estudos das particularidades das características das transmissões ópticas. A partir destas definições, foram realizadas análises adicionais a fim de verificar o impacto com relação ao tráfego gerado em enlaces de diferentes larguras de banda, com a definição original do protocolo, e com a extensão proposta, permitindo uma comparação entre ambos. / This thesis presents an analysis of Path Computation Element Architecture (PCE) as an alternative to be implemented in heterogeneous network inter-domain routing, in other words, environments where optical domains are integrated with the electronic domains of conventional networks. Also, the ability of PCE to manage issues regarding the transmission quality of the optical signal, the QoT (Quality of Transmission), is presented. Objectives and functionality of the PCE mechanism in integrated networks is detailed. Concepts and definitions regarding optical networks and their main elements, the aim of interconnection with conventional networks to build a unified and integrated network, the role of control planes, and the main routing mechanisms are also presented. The analysis of the PCE was focused on the behavior of its main protocol, called PCE Protocol. Specifically, the analysis was performed on both its request and response messages, in addition, the interference in the traffic of the links where these messages had been introduced was also analyzed. Afterwards, an extension of the PCE Protocol parameters was proposed based on the study of optical transmission characteristics, with the aim of meeting specific QoT requirements. From these definitions, further analyses of the impact on the traffic in links with different bandwidths were performed, using the PCE protocol, with and without the proposed extension, allowing a comparison between them.

Este trabalho apresenta uma análise sobre a Arquitetutra PCE (Path Computation Element), como alternativa para o roteamento inter-domínios em redes heterogêneas, ou seja, em ambientes onde ocorre a integração do domínio óptico, das redes de transporte ópticas, com o domínio eletrônico, das redes convencionais, tratando inclusive com questões de qualidade de transmissão do sinal óptico, ou QoT (Quality of Transmission). Os objetivos e o funcionamento do mecanismo do PCE em redes integradas são detalhados. São apresentados também os conceitos e definições das redes ópticas, bem como seus principais elementos, a proposta de interconexão das mesmas com as redes convencionais provendo uma rede única e integrada, o papel dos planos de controle, e os principais mecanismos de roteamento. A análise do PCE foi direcionada para o comportamento do principal protocolo utilizado na sua arquitetura, denominado PCE Protocol. De forma mais específica, foi realizada a análise de suas mensagens de requisição de rotas e das mensagens de respostas a estas requisições, e sua interferência no tráfego dos enlaces das redes onde são introduzidas. A partir daí é apresentada uma proposta de extensão de parâmetros para o protocolo PCE Protocol, com o objetivo de atender necessidades específicas de QoT, baseado em estudos das particularidades das características das transmissões ópticas. A partir destas definições, foram realizadas análises adicionais a fim de verificar o impacto com relação ao tráfego gerado em enlaces de diferentes larguras de banda, com a definição original do protocolo, e com a extensão proposta, permitindo uma comparação entre ambos. / This thesis presents an analysis of Path Computation Element Architecture (PCE) as an alternative to be implemented in heterogeneous network inter-domain routing, in other words, environments where optical domains are integrated with the electronic domains of conventional networks. Also, the ability of PCE to manage issues regarding the transmission quality of the optical signal, the QoT (Quality of Transmission), is presented. Objectives and functionality of the PCE mechanism in integrated networks is detailed. Concepts and definitions regarding optical networks and their main elements, the aim of interconnection with conventional networks to build a unified and integrated network, the role of control planes, and the main routing mechanisms are also presented. The analysis of the PCE was focused on the behavior of its main protocol, called PCE Protocol. Specifically, the analysis was performed on both its request and response messages, in addition, the interference in the traffic of the links where these messages had been introduced was also analyzed. Afterwards, an extension of the PCE Protocol parameters was proposed based on the study of optical transmission characteristics, with the aim of meeting specific QoT requirements. From these definitions, further analyses of the impact on the traffic in links with different bandwidths were performed, using the PCE protocol, with and without the proposed extension, allowing a comparison between them.

Cette thèse porte sur l'optimisation des performances des systèmes de transmission multimédias MIMO-OFDM prenant conjointement en compte les imperfections de l'amplificateur de puissance et les distorsions du canal. Les fluctuations d'amplitude des signaux OFDM, caractérisées par un PAPR élevé, rendent la transmission vulnérable à la non-linéarité de l'amplificateur de puissance. On propose dans un premier temps une méthode permettant d'améliorer les performances de la méthode Tone Reservation en termes de gain de réduction du PAPR et de rapidité de convergence, en associant les échantillons de l'Intervalle de Garde aux Sous-Porteuses Nulles. Les simulations en présence d'un amplificateur de puissance à effets mémoire et d'un canal radio basé sur un modèle de propagation réaliste montrent que la méthode proposée offre de bonnes performances tout en respectant les spécifications fréquentielles, dans le cadre du standard IEEE 802.11a. Dans un second temps, on propose d'étudier l'impact de la non-linéarité dans un système MIMO-OFDM précodé dédié à la transmission d'images JPWL, respectant la norme IEEE 802.11n. On montre que la non-linéarité affecte la robustesse de transmission contre les erreurs de transmission et dégrade considérablement la qualité visuelle des images reçues. Enfin, on propose une stratégie de précodage originale prenant conjointement en compte l'amplificateur de puissance, le canal de transmission et le contenu de l'image à transmettre. Cette stratégie alloue successivement la puissance sur les sous-canaux SISO issus de la décomposition du canal MIMO afin de maximiser la qualité visuelle des images reçues tout en réduisant la puissance totale d'émission. Les résultats de simulation montrent que cette nouvelle stratégie qui considère un amplificateur et un canal réalistes, permet de garantir la robustesse de transmission et d'améliorer la qualité visuelle des images reçues. / This thesis focuses on the optimization of multimedia transmissions in MIMO-OFDM systems by jointly taking into account the power amplifier non-linearity and the wireless channel distortions. The OFDM modulation generates a high peak fluctuation, measured by the PAPR, which is affected by the RF non-linearity such as the power amplifier, reducing the transmission quality. We first propose a new method to improve the Tone Reservation method performances in terms of PAPR reduction gain and convergence speed, by including the samples of the Guard Interval Signal in the optimization algorithm. Simulations results using a power amplifier model with memory effects and a radio channel based on a realistic propagation model show that the new method offers the better performances, while respecting the IEEE 802.11a spectrum mask. Secondly, we propose to study the impact of power amplifier nonlinearity on the transmission of scalable image contents over a precoded Closed-Loop MIMO-OFDM system. The simulations in a realistic context, under the standard IEEE 802.11n standard show that the RF non-linearity affects the robustness against transmission errors and highly degrades the visual quality of the received JPWL images. Finally, we propose a new precoding strategy which jointly takes into account the power amplifier, the radio channel and the image content to be transmitted. This strategy successively allocates power between the SISO sub-channels obtained from the MIMO channel decomposition in order to maximize the visual quality of the received images, while reducing the total output power. Simulations with a realistic power amplifier model, associated with a realistic channel model show that this new strategy ensures a robust transmission and improves the visual quality of the received images.

This thesis presents elliptical rolling contact joints as an alternative to circular rolling contact and conventional revolute joints where high quality force transmission "low friction and backlash" with variable output are desired. Parameters specific to the joint and its position are developed in terms of relative link angles and elliptical surface geometry. These parameters are used to generate the basic forward kinematics for elliptical rolling link toggle mechanisms with oscillatory motion and high mechanical advantage. As large compressive loads are characteristic of such mechanisms, stress conditions are identified and principles for joint stability with variable, precision outputs are discussed. Finally, application is made to self-adjusting passive force closures with a case study of the MUSCLE Brake (Multi-toggle Self-adjusting Connecting-Linked Electromechanical) disc brake caliper. Elliptical rolling contact joints are shown to offer several benefits over circular rolling contact, including: reduced Hertz contact stresses and flexure bending stresses, variable output velocity, maximum use of contact interface by distributing small rotations across surfaces of small curvature, reduced forces on stabilizing members, increased mechanical advantage due to eccentricity, and no-slip pure rolling provided exclusively by connecting links (or flexures) without the need for gear teeth or friction.

Η πρόσφατη τεχνολογική ανάπτυξη των οπτικών ενισχυτών, πολυπλεκτών/αποπλεκτών, οπτικών διακοπτών καθώς και άλλων οπτικών συσκευών μας οδηγεί στο να ελπίζουμε ότι σύντομα στο μέλλον θα υλοποιηθεί ένα πλήρες οπτικό (all optical), WDM (wavelength division multiplexing) δίκτυο που να ικανοποιεί και την ανάγκη για μεγάλα μεγέθη χωρητικότητας. Σε ένα τέτοιο δίκτυο η μετατροπή του οπτικού σήματος σε ηλεκτρονικό και εκ νέου στο οπτικό (ΟΕΟ) δεν θα χρησιμοποιείται στους ενδιάμεσους κόμβους, και αυτό συμβάλει σε οικονομικότερες υλοποιήσεις των οπτικών δικτύων. Σε ένα WDM δρομολογούμενο δίκτυο, τα δεδομένα μεταφέρονται μέσω ενός οπτικού καναλιού, lightpath, στους κόμβους του δικτύου που συνδέονται με οπτικές ίνες. Στις πλείστες των περιπτώσεων, κατά την άφιξη ενός lightpath σε κάποιο κόμβο, εφαρμόζεται σε αυτό οπτικό-ηλεκτρονική μετατροπή και αντίστροφα, ούτως ώστε το σήμα να αναδημιουργηθεί λόγω των απωλειών που υπέστη κατά την μεταφορά, ή ακόμη για να αναλυθεί από ενδιάμεσες ηλεκτρονικές συσκευές. Στα μη πλήρη οπτικά δίκτυα, η μεταφορά των δεδομένων γίνεται από κόμβο σε κόμβο κατά μήκος του δικτύου, ούτως ώστε το οπτικό σήμα να ενισχύεται και να αναγεννάτε μέσω της OEO επεξεργασίας. Παρ’ όλα αυτά, η κάθε ενδιάμεση ανάλυση του θέματος σε ένα τέτοιο δίκτυο προϋποθέτει πολύ μεγάλα κόστη λόγω των πολλών συσκευών που απαιτούνται για τη OEO επεξεργασία. Το γεγονός αυτό μας οδηγεί στα ημί-πλήρη δίκτυα όπου η ενίσχυση και αναγέννηση του θέματος δε γίνεται σε όλους τους ενδιάμεσους κόμβους αλλά σε μερικούς από αυτούς. Ο τελικός στόχος όμως είναι η απαλοιφή της ηλεκτρονικής μετατροπής και αυτό οδηγεί στην υλοποίηση των πλήρως οπτικών δικτύων. Στα πλήρη οπτικά δίκτυα, ένα σήμα που μεταδίδεται παραμένει, για όλο το lightpath, στο οπτικό επίπεδο. Έτσι, το πλήρες οπτικό δίκτυο μπορεί να απαλείψει την ασύμφορη OEO μετατροπή. Η αναζήτηση των κατάλληλων μονοπατιών με τα κατάλληλα μήκη κύματος που θα ικανοποιούσε ένα πλήρες οπτικό δίκτυο το οποίο δρομολογείται από ligthpaths, ονομάζεται Routing and Wavelength Assignment (RWA) και αποτελεί ένα από τα σημαντικότερα ζητήματα για το σωστό σχεδιασμό των οπτικών δικτύων τέτοιου είδους. Το πρόβλημα γίνεται ιδιαίτερα πολύπλοκο όταν στην τελική απόφαση θα πρέπει να συμπεριληφθούν και τα χαρακτηριστικά του φυσικού επιπέδου του δικτύου, όπως εξασθένιση του σήματος, μη γραμμικά φαινόμενα, διασπορά κ.ά, η συμβολή των οποίων στην τελική δρομολόγηση δεν θεωρείται αμελητέα (Impairment Aware Routing and Wavelength Assignment, ΙΑ-RWA). Σε αυτή την εργασία μελετάται το RWA πρόβλημα και προτείνεται ένας μονού στόχου γενετικός αλγόριθμος (Single Objective Genetic Algorithm - SOGA), ο οποίος επιλύει ικανοποιητικά το πρόβλημα θεωρώντας στατική κίνηση. Επιπλέον τονίζεται η σημασία των φυσικών παραμέτρων του προβλήματος και πως αυτές επηρεάζουν την απόδοση του πλήρους οπτικού δικτυου. Στη συνέχεια προτείνεται ένας νέος, πολλαπλών στόχων γενετικός αλγόριθμος (multi objective genetic algorithm – MOGA) ο οποίος βελτιστοποιεί τις λύσεις του προβλήματος ικανοποιητικά λαμβάνοντας ταυτόχρονα υπόψη, με έμμεσο τρόπο, και τις φυσικές παραμέτρους. Επίσης προτείνεται και ένας μονού στόχου γενετικός αλγόριθμος οποίος χρησιμοποιεί ένα εργαλείο αποτίμηση της ποιότητας μετάδοσης (Q-TOOL) σαν μέτρο κατά τη διαδικασία εύρεσης ικανοποιητικής λύσης. Το υπόλοιπο της εργασίας οργανώνεται ως ακολούθως: Στην ενότητα 2 παρουσιάζεται μια σύντομη αναφορά στα WDM δίκτυα καθώς και η περιγραφή του RWA και IA-RWA προβλήματος, ενώ στην ενότητα 3 παρουσιάζεται η πρόταση επίλυσης του RWA προβληματος με τη χρήση γενετικών αλγορίθμων. Ακολουθεί στην ενότητα 4 η πρότασή μας για επίλυση του IA-RWA προβλήματος με τη χρήση Multi-objective διαδικασιών βελτιστοποίησης, καθώς και η βελτιστοποίηση του προβλήματος με τη χρήση του Q-TOOL. Τέλος στην ενότητα 5 συνοψίζουμε την εργασία και παρουσιάζουμε τα συμπεράσματα. / The recent development of optical amplifiers, multiplexers / de-multiplexers, optical switches and other optical devices leads us to hope that soon in future all optical, WDM (wavelength division multiplexing) networks will be implemented which that will satisfy the needs for large capacity. In such networks a viable conversion of the optical -> Electronic and back to optical (OEO) will not be used at intermediate nodes, and this will contribute to efficient and economical implementation. The search for the appropriate paths with the appropriate wavelengths that meet the requirement in all optical networks is called Routing and Wavelength Assignment (RWA) and is one of the most important issues for proper design of such optical networks. The problem becomes particularly complex when the final decision should include the characteristics of the physical layer of the network, such as attenuation of the signal, nonlinear effects, dispersion, etc., whose contribution to the final result is not considered negligible (Impairment Aware Routing and Wavelength Assignment,IA-RWA). This work studies the RWA problem considering static traffic, and proposes a single-objective genetic algorithm (Single Objective Genetic Algorithm - SOGA), which resolves the problem satisfactorily. Furthermore the work stresses the importance of physical parameters of the problem and how these affect the performance of the all optical networks, and proposes a new, multi-objective genetic algorithm (MOGA) which optimizes the solution of IA-RWA problem adequately taking into account indirectly, and the physical impairments that affect the quality of the signal. In addition, a single objective genetic algorithm is proposed that uses a tool to assess the quality of the transmission signal (Q-TOOL), as a benchmark, in the process of optimization of the solution to the IA-RWA problem.