Next generation optical communication systems will have to transport a significantly increased data volume at a reduced cost per transmitted bit. To achieve these ambitious goals optimum design is crucial in combination with dynamic adaptation to actual traffic demands and improved energy efficiency. In the first part of the book the author elaborates on the design of optical transmission systems. Several methods for efficient numerical simulation are presented ranging from meta-model based optimization to parallelization techniques for solving the nonlinear Schroedinger equation. Furthermore, fast analytical and semi-analytical models are described to estimate the various degradation effects occurring on the transmission line. In the second part of the book operational aspects of optical networks are investigated. Physical layer impairment-aware routing and regenerator placement are studied. Finally, it is analyzed how the energy efficiency of a multi-layer optical core network can be increased by dynamic adaptation to traffic patterns changing in the course of the day.

Next generation optical communication systems will have to transport a significantly increased data volume at a reduced cost per transmitted bit. To achieve these ambitious goals optimum design is crucial in combination with dynamic adaptation to actual traffic demands and improved energy efficiency. In the first part of the book the author elaborates on the design of optical transmission systems. Several methods for efficient numerical simulation are presented ranging from meta-model based optimization to parallelization techniques for solving the nonlinear Schroedinger equation. Furthermore, fast analytical and semi-analytical models are described to estimate the various degradation effects occurring on the transmission line. In the second part of the book operational aspects of optical networks are investigated. Physical layer impairment-aware routing and regenerator placement are studied. Finally, it is analyzed how the energy efficiency of a multi-layer optical core network can be increased by dynamic adaptation to traffic patterns changing in the course of the day.

Diploma Thesis from the year 2002 in the subject Electrotechnology, grade: 1,0, University of Dortmund (Lehrstuhl fur Hochfrequenztechnik), 39 entries in the bibliography, language: English, abstract: Next generation optical communication systems will be characterized by increasing data rates, high signal powers and dense wavelength division multiplexing (DWDM). In future-optical networks channels will be routed through complex, meshed networks (ASTN, Automatically Switched Transport Networks, ITU-T Recommendation G.808 0/Y.1304). These networks will be able to setup transparent optical paths without converting the optical signals to electrical signals. In all-optical networks the physical impairments and degradation effects play an important role. There is a multitude of degradation effects like dispersion, noise, crosstalk, fiber nonlinearities, polarization dependent loss, etc. To enable a fast setup and the best choice of one of the available paths, the signal quality along the whole transmission distance has to be evaluated very fast. Ideally, only a single figure of merit (FOM), e.g. the bit error rate (BER), will be computed, which incorporates all degradation effects. Therefore it is important to characterize the different physical impairments analytically. Signal distortions can be measured by an eye opening penalty (EOP) and degradation effects due to noise by the optical signal-to-noise ratio (OSNR). The goal is to find and calculate these impairments from the signal parameters (modulation format, data rate, duty cycle, channel spacing, etc.) as well as the route parameters (fiber lengths and parameters, EDFA powers, etc.). Due to the need of fast routing algorithms, time-consuming numerical methods or a complete system simulation are not practical. In addition, it is not possible to linearly accumulate the different degradation effects. The focus of this work is to find analytical or heuristic formulas for each degradation effect. These approximation f

Master's Thesis from the year 2001 in the subject Electrotechnology, grade: with distinction, City University London, 50 entries in the bibliography, language: English, abstract: Bragg gratings are important devices for both optical communications and sensing. These devices are used to design very narrow band optical filters, which can be used in wavelength division multiplexing (WDM). It is also perceived that Bragg gratings will be used to compensate the dispersion in modern fibre optic telecommunication networks. Semiconductor gratings are usually integrated into lasers to control the operating wavelength. City University Photonic Modelling Group is a world leading research group on the use of rigorous numerical techniques to design and optimise advanced photonic devices for optical communications. The research group has already achieved results on hypothetical one-dimensional (1-D) and realistic two-dimensional (2-D) structures. In this project a combination of three numerical methods has been used, all of which are rigorous, to simulate realistic three-dimensional (3-D) structures in semiconductor waveguides. The combination of these three accurate methods, the finite element method (FEM), the least squares boundary residual (LSBR) method and the transfer matrix method (TMM) turned out to be superior to the widely used coupled mode theory (CMT). The numerical study of different Bragg gratings shows interesting dependencies of the characteristics of the gratings on the different design parameters. The work was carried out for different mesh distributions, different numbers of mesh divisions and different computational parameters. Another focus of the work was on the stability of the transmission and reflection coefficients obtained from the LSBR program. Furthermore the effect of inaccuracy occurring during the fabrication process has been studied. The results of this work have been compared to results found by other groups and fellows. We can say that this proj

Diplomarbeit aus dem Jahr 2005 im Fachbereich BWL - Unternehmensforschung, Operations Research, Note: gut, FernUniversitat Hagen (Wirtschaftsinformatik), 62 Quellen im Literaturverzeichnis, Sprache: Deutsch, Abstract: Das Transportwesen und die damit verbundene logistische Planung des Warenflusses sowie die Tourenplanung spielen eine wichtige Rolle im betriebswirtschaftlichen Umfeld. Unter Tourenplanung versteht man allgemein eine Klasse von Planungsproblemen, die verschiedene Auspragungen bezuglich der Zielfunktion und den Nebenbedingungen aufweisen. Eine konkrete Problemstellung der Tourenplanung sieht etwa folgendermassen aus: Von einem oder mehreren Lagern ausgehend, sind mit einem vorhandenen Fuhrpark, ein oder mehrere Kunden entsprechend den vorhandenen Auftragen zu beliefern. Hierbei ist die Kapazitat der Fahrzeuge beschrankt. Eine in der betrieblichen Praxis haufig auftretende weitere Restriktion ist die Vorgabe von Zeitfenstern. Unter Zeitfenstern versteht man Intervalle, die den fruhesten und spatesten Beginn einer Auftragsdurchfuhrung begrenzen. Ein typisches Beispiel fur ein Tourenplanungsproblem mit Zeitfenstern ist die just-in-time" Belieferung durch Paketdienste. Im angelsachsischen Sprachbereich wird das Problem auch als vehicle routing problem with time windows" (VRPTW) bezeichnet. In der Regel liegt dem VRPTW eine hierarchische Zielsetzung zugrunde, die die benotigte Fahrzeugzahl in einem ersten Schritt und die Minimierung der Gesamtdistanz in einem zweiten Schritt berucksichtigt. Das VRPTW ist ein kombinatorisches Optimierungsproblem, welches zur Klasse der NP-harten (engl.: non-deterministic polynomial time) Probleme gezahlt wird. Dies bedeutet, dass bislang kein Algorithmus bekannt ist, mit dem eine optimale Losung in polynomialer Zeit gefunden werden kann. Stattdessen wachst der Losungsaufwand mit der Problemgrosse exponentiell. Deshalb bietet sich der Einsatz von heuristischen Verfahren an. Hierzu zahlen insbesondere Metaheuristiken, wie das