Guest editorial : In Journal of networks, v.6 n.1

In recent years, networking of computing devices has been going through rapid evolution and thus continuing to be an ever expanding area of importance. Different technologies, protocols, services and usage patterns have contributed to the major research interests in this area of computer science. The current special issue is an effort to bring forward some of these interesting developments that are being pursued by researchers at present in different parts of the globe. Our objective is to provide the readership with some insight into the latest innovations in computer networking through this

Análisis y simulación de los efectos no lineales en la capa física de una red de nueva generación (NGN)

Las redes PON (redes ópticas pasivas) constituyen una de las soluciones más factibles al incremento de la demanda de ancho de banda de los usuarios. El advenimiento de servicios como voz sobre (VoIP), juegos interactivos, Televisión de alta definición, telefonía celular 4G, telepresencia, telemedicina, necesitan de un gran ancho de banda, el único medio de trasmisión que permite tales anchos de banda es la fibra óptica y particularmente las redes ópticas pasivas, que no utilizan elementos activos, son una solución viable para llegar a los usuarios de casas, oficinas, empresas y brindarles todos estos servicios. Sin embargo, existen varios efectos generados por la fibra óptica sobre la señal transmitida, tales como los efectos no lineales, causados en gran medida por la potencia de trasmisión. Los efectos no lineales se presentan en cuatro formas: la dispersión estimulada de Raman (SRS), la dispersión estimulada de Brillouin (SBS), la modulación de fase cruzada (XPM) y la modulación de las cuatro ondas (FWM). Todos ellos afectan en cierta medida y en ciertas condiciones a la trasmisión de datos en una red WDM/TDM-PON y a una red WDM PON, por lo que es de interés determinar como la señal es afectada por los efectos no lineales. Se analizó dos escenarios el primero con una red PON sin la presencia de los efectos no lineales y el segundo con la presencia de efectos no lineales. Se determinó que el efecto no lineal FWM causa mayores variaciones no lineales de la tasa de bit errado (BER) con respecto a la potencia

Upgrade and extend the reach of the current passive optical network (PON) by using wavelength division multiplexing (WDM) in the standardized optical grid of gigabit PON

Orientadores: Renato Baldini Filho, João Batista RosolemTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Este trabalho apresenta contribuições na evolução da rede óptica passiva em termos do aumento da capacidade e da extensão usando comprimentos de onda sobrepostos dentro da grade espectral padronizada da rede Gigabit PON (GPON). Nesta abordagem quatro sinais em comprimentos de onda distintos são escolhidos dentro da banda de transmissão da GPON entre 1480nm a 1500nm no sentido de descida (downstream) e são transmitidos a partir de um terminal de linha óptica (OLT). Estes quatro sinais se direcionam a quatro diferentes redes de distribuição óptica (ODN). Os sinais de subida (upstream) provenientes das quatro diferentes ODNs são também multiplexados em comprimento de onda dentro da banda upstream do GPON que vai de 1270 a 1360 nm. Provas experimentais do conceito são realizadas a fim de demonstrar a viabilidade desta proposta em uma PON de 20 km servindo 32 ONTs. Em seguida é desenvolvido um estudo de uma PON estendida com a topologia de sopreposição estudada previamente com os canais em comprimento de onda utilizando extensores ópticos do tipo amplificadores ópticos semicondutores (SOA), mudando assim a característica de passividade da rede e tendo um alcance de 58 km. Finalmente é apresentado um estudo relacionado aos dois tópicos anteriores no qual a alimentação dos SOAs é feita de através da técnica de alimentação pela fibra (PoF) para alimentar amplificadores semicondutores (SOAs) e levar a distância da rede até 50 kmAbstract: This work presents contributions for upgrade and extend the reach of the current passive optical network (PON) by using wavelength division multiplexing (WDM) in the standardized optical grid of gigabit PON. This proposal is named In-band WDM PON overlay. The aim is to increase the number of optical distribution networks (ODNs) fed by a single fiber while preserving the users bandwidth. In this approach four downstream (DS) wavelength signals are transmitted from an optical line terminal (OLT) to four distinct ODNs using standard DS PON spectrum ranging from 1480 to 1500 nm. The upstream (US) signals from the four ODNs are also wavelength multiplexed within the standardized US PON spectrum ranging from 1270 to 1330 nm. Experimental proofs of concept are presented in a 20 km PON serving 32 ONTs. An extended PON proposal is presented using semiconductor amplifiers (SOAs) powered electrically and have a ranging 58 km long. Notice that this approach, changes the network passivity. Other contribution is concern to an innovative proposal to extend GPON and XGPON networks by using the power over fiber technique to amplify the signal to reach 50 kmDoutoradoTelecomunicações e TelemáticaDoutor em Engenharia Elétric

Optimization of emerging extended FTTH WDM/TDM PONs and financial overall assessment

Optical access technology has experienced a boost in the last years, thanks to the continuously migrating multimedia services that are offered over the internet. Though the technologies used for deploying Fiber-To-The-x (FTTx) and Fiber-to-the-Home (FTTH) are mostly based on either Active solutions or as far as Passsive Optical Networks (PONs) is concerned, in Time Division Multiplexing (TDM), an evolution towards Hybrid solutions such as Wavelength Division Multiplexing/Time Division Multiplexing (WDM/TDM) can be foreseen. What needs to be researched and finally established are the exact designs for this important step of integration, which should be optimized in terms of transmission performance and cost, to address all requirements of next-generation passive optical networks. As the most critical elements in optical access network, the design and its cost are the main topics of this discussion. The covered topics span over a wide range and include cost estimation of several optical network technologies - architectures and their comparison and furthermore, subjects of design optimization. In this last category, in-line remote amplification, use of an alternative and an extended frequency band, dispersion compensation and equalization techniques have been examined as well as a combination of the aforementioned means of network optimization. Next to the principal proof of the proposed techniques, the benefits are highlighted in different case studies, while the most representative designs are further discussed

Déploiement de réseaux optiques d'accès NGPON dans des métropoles de pays en développement : proposition de nouvelles techniques d'implémentation de l'OFDM

The rapid development of multimedia services and applications such as broadband Internet, 3G, LTE, has led customers to force operators to increase throughput of all network segments, including the access network. Solutions using optical fiber tend to gradually replace cable based-copper or coaxial communications to ensure larger transfer capacity. The optical fiber is a very attractive medium because its linear attenuation is very low and its bandwidth very high. However, the chromatic dispersion of the fiber associated with the chirp of the optical sources limit the rise in flowrate in future optical access networks (beyond rates of 10 Gb/s) NG-PON (Next Generation Passive Optical Network). In this context, modulation formats with higher spectral efficiency than NRZ-OOK could be selected. OFDM is a solution to increase the spectral efficiency, while ensuring a better performance and high robustness against frequency selective channel such as fiber optics. In this thesis, we proposed a new OFDM techniques implementation for NG-PON and evaluated their performance in an IM/DD channel. We showed by simulations system of a realistic optical channel, that New DCO, New INC-ACO and DC-ACO OFDM techniques are able to increase the limited transmission distances imposed by the NRZ-OOK modulation with the use of low-cost components. Thus, we showed that using the “Minimization and E-Tight (MET)”or the Levin-Campello algorithm, the New DCO and DC-ACO techniques permit to achieve data rates of 10 Gb/s with a split ratio of 1 × 64 over a distance of 70 km with New DCO and 55 km for DC-ACO. Then we conclude that the New AMOFDM approach is a good choice for the deployment of optical access networks in metropolitan cities of developing countries.L’évolution rapide des services et applications multimédias (Internet haut débit, 3G, LTE) a entrainé un besoin chez les clients qui contraint les opérateurs à augmenter le débit de tous les segments du réseau, y compris le réseau d’accès. Les solutions utilisant la fibre optique tendent à remplacer progressivement les liaisons câblées (cuivre ou coaxial) afin de garantir des capacités de transfert plus importantes. La fibre optique est un medium très attractif car son atténuation linéique est très faible et sa bande passante importante. Cependant la dispersion chromatique de la fibre associée au chirp des sources optiques limite la montée en débit dans les futurs réseaux d’accès optiques (débits au-delà de 10 Gb/s) NG-PON (Next Generation Passive Optical Network). Dans ce contexte, des formats de modulation à efficacité spectrale meilleure que le NRZ pourraient être retenus. L’OFDM est une solution pour accroître l’efficacité spectrale, tout en garantissant une meilleure performance et une grande robustesse face aux canaux sélectifs en fréquence comme la fibre optique. Dans ce travail de thèse, nous avons proposé de nouvelles techniques d’implémentation de l’OFDM pour le NG-PON et évalué leurs performances dans un canal IM/DD. Nous avons montré par des simulations système dans un canal optique réaliste, que les techniques New DCO, New INC-ACO et DC-ACO sont capables d’augmenter les limitations de distances de transmission imposées par la modulation NRZ-OOK (Non-Return to Zero On-Off Keying) avec l’utilisation de composants bas coût. Ainsi, nous avons montré qu’avec les méthodes «MET (Minimization E-Tight)» et Levin-Campello, les techniques New DCO et DC-ACO permettent de réaliser des débits de 10 Gb/s sur une distance de 70 km en New DCO et 55 km en DC-ACO avec un taux de partage de 1×64. Cela permet d’affirmer que l’approche New AMOFDM serait un bon candidat pour le déploiement de réseaux d’accès optiques dans les métropoles de pays en développement