Automatic DGD and GVD compensation at 640 Gb/s based on scalar radio-frequency spectrum measurement

We demonstrate what we believe to be the first real-time impairment-cancellation system for groupvelocity dispersion (GVD) and differential group delay (DGD) for a 640 Gb/s single-channel signal. Simultaneous compensation of two independent parameters is demonstrated by feedback control of separate GVD and DGD compensators using an impairment monitor based on an integrated all-optical radio-frequency (RF) spectrum analyzer.We show that low-bandwidth measurement of only a single tone in the RF spectrum is sufficient for automatic compensation for multiple degrees of freedom using a multivariate optimization scheme

Performance comparison of 40 Gb/s ULH transmissions using CSRZ-ASK or CSRZ-DPSK modulation formats on Ultra Wave™ fiber

In this work we present extensive comparisons between numerical modelling and experimental measurements of the transmission performance of either CSRZ-ASK or CSRZ-DPSK modulation formats for 40-Gb/s WDM ULH systems on UltraWave™ fiber spans with all-Raman amplification. We numerically optimised the amplification and the signal format parameters for both CSRZ-DPSK and CSRZ-ASK formats. Numerical and experimental results show that, in a properly optimized transmission link, the DPSK format permits to double the transmission distance (for a given BER level) with respect to the ASK format, while keeping a substantial OSNR margin (on ASK modulation) after the propagation in the fiber line. Our comparison between numerical and experimental results permits to identify what is the most suitable BER estimator in assessing the transmission performance when using the DPSK format. © 2007 Optical Society of America

Cognition procedures for optical network design and optimization

Telecom carriers have to adapt their networks to accommodate a growing volume of users, services and traffic. Thus, they have to search a continuous maximization of efficiency and reduction in costs. This thesis identifies an opportunity to accomplish this aim by reducing operation margins applied in the optical link power budgets, in optical transport networks. From an operational perspective, margin reduction will lead to a fall of the required investments on transceivers in the whole transport network. Based on how human learn, a cognitive approach is introduced and evaluated to reduce the System Margin. This operation margin takes into account, among other constraints, the long-term ageing process of the network infrastructure. Telecom operators normally apply a conservative and fixed value established during the design and commissioning phases. The cognitive approach proposes a flexible and variable value, adapted to the network conditions. It is based on the case-based reasoning machine learning technique, which has been further developped. Novel learning schemes are presented and evaluated. The cognition solution proposes a new lower launched power guaranteeing the quality of service of the new incoming lightpath. It will lead to provide transmission power savings with appropiate success rates when applying the cognitive approach. To this end, it relies on transmission values applied in past and successful similar network situations. They are stored in a knowledge base or memory of the system. Moreover, regarding the knowledge base, a static and a dynamic approaches have been developped and presented. In the last case, five new dynamic learning algorithms are presented and evaluated. In the static context, savings in transmission power up to 48% are achieved and the resulting System Margin reduction. Furthermore, the dynamic renewal of the knowledge base improves mean savings in launched power up to 7% or 18% with respect to the static approach, depending on the path. Thus, the cognitive approach appears as useful to be applied in commercial optical transport networks with the aim of reducing the operational System Margin.Los operadores de telecomunicaciones tienen que adaptar constantemente sus redes para acoger el volumen creciente de usuarios, servicios y tráfico asociado. Han de buscar constantemente una maximización de la eficiencia en la operación, así como una reducción continua de costes. Esta tesis identifica una oportunidad para alcanzar este objetivo por medio de la reducción de los márgenes operacionales aplicados en los balances de potencia en una red óptica de transporte. Desde un punto de vista operacional, la reducción de márgenes operativos conlleva una optimización de las inversiones requeridas en transceivers, entre otros puntos. Así, basándonos en cómo aprendemos los humanos, se introduce y evalúa una aproximación cognitiva para reducir el System Margin. Este margen operativo se introduce en el balance de potencia, entre otros puntos, para compensar el proceso de envejecimiento a largo plazo de la infraestrcutura de red. Los operadores emplean normalmente un valor fijo y conservador, que se establece durante el diseño y comisionado de la red. Nuestra aproximación cognitiva propone en su lugar un valor flexible y variable, que se adapta a las condiciones de red actuales. Se basa en la técnica de machine learning conocida como case-based reasoning, que se desarrolla más profundamente. Se han propuesto y evaluado nuevos esquemas de aprendizaje. La solución cognitiva propone un nuevo valor más bajo de potencia transmitida, que garantiza la calidad de servicio requerida por el nuevo lighpath entrante. La propuesta logra ahorros en la potencia transmitida, a la vez que garantiza una tasa de éxito correcta cuando aplicamos esta solución cognitiva. Para ello, se apoya en la potencia transmitida en situaciones pasadas y similares a la actual, donde se transmitió una potencia que aseguró el correcto establecimiento del lighpath. Esta información se almacena en una base de conocimiento. En este sentido, se han desarrollado y presentado dos aproximaciones: una base de conocimiento estática y otra dinámica. En el caso del contexto dinámico, se han desarrollado y evaluado cinco nuevos algoritmos de aprendizaje. En el contexto estático, se consigue un ahorro en potencia de hasta un 48%, con la correspondiente reducción del System Margin. En el contexto dinámico, la actualización online de la base de conocimiento proporciona adicionalmente una ganancia en potencia transmitida con respecto a la aproximación estática de hasta un 7% o un 18%, dependiendo de la ruta. De esta forma se comprueba que la propuesta cognitiva se revela como útil y aplicable sobre una red óptica de transporte comercial con el objetivo de reducir el margen operativo conocido como System Margin.Postprint (published version

Cognition procedures for optical network design and optimization

Telecom carriers have to adapt their networks to accommodate a growing volume of users, services and traffic. Thus, they have to search a continuous maximization of efficiency and reduction in costs. This thesis identifies an opportunity to accomplish this aim by reducing operation margins applied in the optical link power budgets, in optical transport networks. From an operational perspective, margin reduction will lead to a fall of the required investments on transceivers in the whole transport network. Based on how human learn, a cognitive approach is introduced and evaluated to reduce the System Margin. This operation margin takes into account, among other constraints, the long-term ageing process of the network infrastructure. Telecom operators normally apply a conservative and fixed value established during the design and commissioning phases. The cognitive approach proposes a flexible and variable value, adapted to the network conditions. It is based on the case-based reasoning machine learning technique, which has been further developped. Novel learning schemes are presented and evaluated. The cognition solution proposes a new lower launched power guaranteeing the quality of service of the new incoming lightpath. It will lead to provide transmission power savings with appropiate success rates when applying the cognitive approach. To this end, it relies on transmission values applied in past and successful similar network situations. They are stored in a knowledge base or memory of the system. Moreover, regarding the knowledge base, a static and a dynamic approaches have been developped and presented. In the last case, five new dynamic learning algorithms are presented and evaluated. In the static context, savings in transmission power up to 48% are achieved and the resulting System Margin reduction. Furthermore, the dynamic renewal of the knowledge base improves mean savings in launched power up to 7% or 18% with respect to the static approach, depending on the path. Thus, the cognitive approach appears as useful to be applied in commercial optical transport networks with the aim of reducing the operational System Margin.Los operadores de telecomunicaciones tienen que adaptar constantemente sus redes para acoger el volumen creciente de usuarios, servicios y tráfico asociado. Han de buscar constantemente una maximización de la eficiencia en la operación, así como una reducción continua de costes. Esta tesis identifica una oportunidad para alcanzar este objetivo por medio de la reducción de los márgenes operacionales aplicados en los balances de potencia en una red óptica de transporte. Desde un punto de vista operacional, la reducción de márgenes operativos conlleva una optimización de las inversiones requeridas en transceivers, entre otros puntos. Así, basándonos en cómo aprendemos los humanos, se introduce y evalúa una aproximación cognitiva para reducir el System Margin. Este margen operativo se introduce en el balance de potencia, entre otros puntos, para compensar el proceso de envejecimiento a largo plazo de la infraestrcutura de red. Los operadores emplean normalmente un valor fijo y conservador, que se establece durante el diseño y comisionado de la red. Nuestra aproximación cognitiva propone en su lugar un valor flexible y variable, que se adapta a las condiciones de red actuales. Se basa en la técnica de machine learning conocida como case-based reasoning, que se desarrolla más profundamente. Se han propuesto y evaluado nuevos esquemas de aprendizaje. La solución cognitiva propone un nuevo valor más bajo de potencia transmitida, que garantiza la calidad de servicio requerida por el nuevo lighpath entrante. La propuesta logra ahorros en la potencia transmitida, a la vez que garantiza una tasa de éxito correcta cuando aplicamos esta solución cognitiva. Para ello, se apoya en la potencia transmitida en situaciones pasadas y similares a la actual, donde se transmitió una potencia que aseguró el correcto establecimiento del lighpath. Esta información se almacena en una base de conocimiento. En este sentido, se han desarrollado y presentado dos aproximaciones: una base de conocimiento estática y otra dinámica. En el caso del contexto dinámico, se han desarrollado y evaluado cinco nuevos algoritmos de aprendizaje. En el contexto estático, se consigue un ahorro en potencia de hasta un 48%, con la correspondiente reducción del System Margin. En el contexto dinámico, la actualización online de la base de conocimiento proporciona adicionalmente una ganancia en potencia transmitida con respecto a la aproximación estática de hasta un 7% o un 18%, dependiendo de la ruta. De esta forma se comprueba que la propuesta cognitiva se revela como útil y aplicable sobre una red óptica de transporte comercial con el objetivo de reducir el margen operativo conocido como System Margin

Fast synchronization 3R burst-mode receivers for passive optical networks

This paper gives a tutorial overview on high speed burst-mode receiver (BM-RX) requirements, specific for time division multiplexing passive optical networks, and design issues of such BM-RXs as well as their advanced design techniques. It focuses on how to design BM-RXs with short burst overhead for fast synchronization. We present design principles and circuit architectures of various types of burst-mode transimpedance amplifiers, burst-mode limiting amplifiers and burst-mode clock and data recovery circuits. The recent development of 10 Gb/s BM-RXs is highlighted also including dual-rate operation for coexistence with deployed PONs and on-chip auto reset generation to eliminate external timing-critical control signals provided by a PON medium access control. Finally sub-system integration and state-of-the-art system performance for 10 Gb/s PONs are reviewed

Coexistence of optical systems on a physical layer

Tato diplomová práce se zabývá koexistencí optických systémů na společné fyzické vrstvě. Cílem této práce je analýza interakcí mezi různými optickými systémy na fyzické vrstvě, přičemž dílčím cílem je porovnání integrace těchto systémů za různých provozních podmínek. Data pro tuto práci byla získána pomocí simulačního prostředí Optsim. Na základě výsledků koexistence různých systémů za různých provozních podmínek lze vyvodit závěr, zda je možné systémy sloučit či se tato varianta nasazení nedoporučuje.This thesis deals with coexistence of optical systems on a physical layer. The main objective of this thesis is to analyse interactions between multiple optical systems at the physical layer, while partial goal is to compare the integration of these systems under different system conditions. Data for this study were obtained by computer simulation in Optsim environment. On the basis of the resulting models of coexistence of different transmission systems under various system conditions it can be concluded, whether it is recommended to combine certain systems or not

Transparent heterogeneous terrestrial optical communication networks with phase modulated signals

This thesis presents a large scale numerical investigation of heterogeneous terrestrial optical communications systems and the upgrade of fourth generation terrestrial core to metro legacy interconnects to fifth generation transmission system technologies. Retrofitting (without changing infrastructure) is considered for commercial applications. ROADM are crucial enabling components for future core network developments however their re-routing ability means signals can be switched mid-link onto sub-optimally configured paths which raises new challenges in network management. System performance is determined by a trade-off between nonlinear impairments and noise, where the nonlinear signal distortions depend critically on deployed dispersion maps. This thesis presents a comprehensive numerical investigation into the implementation of phase modulated signals in transparent reconfigurable wavelength division multiplexed fibre optic communication terrestrial heterogeneous networks. A key issue during system upgrades is whether differential phase encoded modulation formats are compatible with the cost optimised dispersion schemes employed in current 10 Gb/s systems. We explore how robust transmission is to inevitable variations in the dispersion mapping and how large the margins are when suboptimal dispersion management is applied. We show that a DPSK transmission system is not drastically affected by reconfiguration from periodic dispersion management to lumped dispersion mapping. A novel DPSK dispersion map optimisation methodology which reduces drastically the optimisation parameter space and the many ways to deploy dispersion maps is also presented. This alleviates strenuous computing requirements in optimisation calculations. This thesis provides a very efficient and robust way to identify high performing lumped dispersion compensating schemes for use in heterogeneous RZ-DPSK terrestrial meshed networks with ROADMs. A modified search algorithm which further reduces this number of configuration combinations is also presented. The results of an investigation of the feasibility of detouring signals locally in multi-path heterogeneous ring networks is also presented

Physical Layer Impairments Aware Dynamic Lightpath Provisioning In Mixed Line Rate Wdm Networks

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2014Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2014Bu tez çalışmasında, fiziksel katman bozukluklarını dikkate alarak, çoklu veri iletişim hızlı ağlarda dinamik olarak gelen bağlantı istekleri için ısıkyolu kurma problemi ele alınmıştır. Problemde verilenler; dinamik olarak gelen farklı kapasitelerde bağlantı istekleri, fiziksel topoloji, fiziksel hatların taşıyabildiği dalgaboyu miktarı, ağın anlık durumu ve fiziksel katman bozukluklarını dikkate alırken kullanılacak olan parametrelerdir. Problemde istenilen ise; gelen bağlantı isteklerinin mümkün olduğu kadar fazlasını kurabilmek maksadı ile uygun yol ve dalgaboyunun bulunmasıdır. Bunu gerçekleştirirken, hem kurulacak olan ışıkyolunun sinyal kalitesinin kabul edilebilir bit hata oranını karşılaması, hem de sistemde daha önceden kurulmuş olan ışıkyollarının sinyal kalitesinin kabul edilebilir sınırların altına inmesini engellemek gerekmektedir. Bu tez çalışmasında, kurulabilen ışıkyolu miktarını artırmak maksadı ile ışıkyolunun sisteme giriş gücü de ayrıca ele alınmıştır.In this thesis, we studied the impairment-aware lightpath provisioning problem for dynamic connection requests in MLR networks. Given, a dynamic connection request with a given rate, physical topology, number of wavelengths carried by each fiber, current network state, and PLI parameters, our aim is to determine the route and wavelength over which the lightpath should be set up, in order to be able to maximize the number of established connections while satisfying the given bit-error rate (BER) for the incoming connection, and to avoid disrupting the existing lightpaths. We also evaluate the launch power of the lightpath to maximize the established connections.DoktoraPh

Quasi-lossless data transmission with ultra-long Raman fibre laser based amplification

The project consists of an experimental and numerical modelling study of the applications of ultra-long Raman fibre laser (URFL) based amplification techniques for high-speed multi-wavelength optical communications systems. The research is focused in telecommunications C-band 40 Gb/s transmission data rates with direct and coherent detection. The optical transmission performance of URFL based systems in terms of optical noise, gain bandwidth and gain flatness for different system configurations is evaluated. Systems with different overall span lengths, transmission fibre types and data modulation formats are investigated. Performance is compared with conventional Erbium doped fibre amplifier based system to evaluate system configurations where URFL based amplification provide performance or commercial advantages

Control plane routing in photonic networks

The work described in the thesis investigates the features of control plane functionality for routing wavelength paths to serve a set of sub-wavelength demands. The work takes account of routing problems only found in physical network layers, notably analogue transmission impairments. Much work exists on routing connections for dynamic Wavelength-Routed Optical Networks (WRON) and to demonstrate their advantages over static photonic networks. However, the question of how agile the WRON should be has not been addressed quantitatively. A categorization of switching speeds is extended, and compared with the reasons for requiring network agility. The increase of effective network capacity achieved with increased agility is quantified through new simulations. It is demonstrated that this benefit only occurs within a certain window of network fill; achievement of significant gain from a more-agile network may be prevented by the operator’s chosen tolerable blocking probability. The Wavelength Path Sharing (WPS) scheme uses semi-static wavelengths to form unidirectional photonic shared buses, reducing the need for photonic agility. Making WPS more practical, novel improved routing algorithms are proposed and evaluated for both execution time and performance, offering significant benefit in speed at modest cost in efficiency. Photonic viability is the question of whether a path that the control plane can configure will work with an acceptable bit error rate (BER) despite the physical transmission impairments encountered. It is shown that, although there is no single approach that is simple, quick to execute and generally applicable at this time, under stated conditions approximations may be made to achieve a general solution that will be fast enough to enable some applications of agility. The presented algorithms, analysis of optimal network agility and viability assessment approaches can be applied in the analysis and design of future photonic control planes and network architectures