Wavelength reconfigurability for next generation optical access networks

Next generation optical access networks should not only increase the capacity but also be able to redistribute the capacity on the fly in order to manage larger variations in traffic patterns. Wavelength reconfigurability is the instrument to enable such capability of network-wide bandwidth redistribution since it allows dynamic sharing of both wavelengths and timeslots in WDM-TDM optical access networks. However, reconfigurability typically requires tunable lasers and tunable filters at the user side, resulting in cost-prohibitive optical network units (ONU). In this dissertation, I propose a novel concept named cyclic-linked flexibility to address the cost-prohibitive problem. By using the cyclic-linked flexibility, the ONU needs to switch only within a subset of two pre-planned wavelengths, however, the cyclic-linked structure of wavelengths allows free bandwidth to be shifted to any wavelength by a rearrangement process. Rearrangement algorithm are developed to demonstrate that the cyclic-linked flexibility performs close to the fully flexible network in terms of blocking probability, packet delay, and packet loss. Furthermore, the evaluation shows that the rearrangement process has a minimum impact to in-service ONUs. To realize the cyclic-linked flexibility, a family of four physical architectures is proposed. PRO-Access architecture is suitable for new deployments and disruptive upgrades in which the network reach is not longer than 20 km. WCL-Access architecture is suitable for metro-access merger with the reach up to 100 km. PSB-Access architecture is suitable to implement directly on power-splitter-based PON deployments, which allows coexistence with current technologies. The cyclically-linked protection architecture can be used with current and future PON standards when network protection is required

Optical switching for dynamic distribution of wireless-over-fiber signals in active optical networks

El continuo crecimiento de ancho de banda demandado por los usuarios finales está provocando una gran exigencia sobre las redes de acceso. Estas exigencias sobre las redes de acceso, que principalmente emplean tecnologías inalámbricas, están migrando hacia el dominio óptico con el fin de soportar estos altos requerimientos de ancho de banda. Dependiendo de los requerimientos y características de los usuarios finales, las redes de acceso óptico han evolucionado en diferentes direcciones. En entornos residenciales y urbanos los usuarios demandan conexiones fijas de alta capacidad y bajo coste. Las redes ópticas pasivas (PON) han cumplido estos requerimiento y son las tecnologías elegidas por los operadores. En los entornos empresariales, en los cuales la calidad y la seguridad son piezas clave, las redes ópticas activas han encontrado su hueco proveyendo flexibilidad, adaptabilidad, alto rendimiento y al mismo tiempo dando soporte a sistemas de control de redes. Los proveedores de equipos están ahora girando su vista hacia nuevos mercados, donde soluciones ópticas puede ser usado eficientemente. El transporte de datos de redes de móviles (o mobile backhaul en ingles) es un mercado que se ha convertido en objetivo principal, ya que el tráfico inalámbrico está creciendo exponencialmente. Nuevos dispositivos, junto a las aplicaciones de gran consumo de ancho de banda, son los principales motivos de este crecimiento. Las tecnologías de banda base puede soportar sobradamente mobile backhaul a las actuales velocidades de transmisión. Sin embargo, debido a la ubicación de nuevas licencias libres disponibles en la banda de frecuencias y el desarrollo de las tecnologías radio a través de fibra permitiendo generación, distribución y recepción óptica de señales, la migración hacia escenarios en los que se use señales inalámbricas a través de fibra son mas probables. Además, teniendo en cuenta aspectos como la seguridad y alta movilidad de los usuarios, todo parece indicar que soluciones activas son más atractivas, siempre y cuando que los consumos de energía se mantengan dentro de límites razonables. En esta tesis, se diseñó una red óptica de acceso basada en tecnologías de radio a través de fibra. El bloque principal de la red fue un conmutador óptico basado en componentes activos (amplificadores ópticos semiconductores); el resto de la red fue diseñada acorde a la distribución por canales del conmutador óptico. Utilizando este conmutador óptico, se realizó una validación experimental de la red. El experimento consistió en una implementación de un sistema de cuatro canales operando en la banda de frecuencia WiMax y empleando una modulación llamada multiplexado de división ortogonal en frecuencia (OFDM) a 625Mb/s por canal. La información fue enviada a través de 20 km de fibra óptica, y el redireccionamiento de la señal fue llevado a cabo por un conmutador de 1 entrada y 16 salidas. El resultado es una degradación imperceptible de la señal en cada canal en el mejor y en mejor escenario en términos de interferencia entre canales. Este sistema cumple con los requisitos de una red de acceso activa para señales de radio a través de una red de acceso óptica

Field-Trial of a high-budget, filterless, lambda-to-the-user, UDWDM-PON enabled by an innovative class of low-cost coherent transceivers

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.We experimentally demonstrate an innovative ultradense wavelength division multiplexing (UDWDM) passive optical networks (PON) that implements the full ¿-to-the-user concept in a filterless distribution network. Key element of the proposed system is a novel class of coherent transceivers, purposely developed with a nonconventional technical approach. Indeed, they are designed and realized to avoid D/A-A/D converter stages and digital signal processing in favor of simple analog processing so that they match system, cost, and power consumption requirements of the access networks without sacrificing the overall performance. These coherent transceivers target different use case scenarios (residential, business, fixed, wireless) still keeping perfect compatibility and co-existence with legacy infrastructures installed to support gray, time division multiplexed PON systems. Moreover, the availability of coherent transceivers of different cost/performance ratios allows for deployments of different quality service grades. In this paper, we report the successful field trial of the proposed systems in a testbed where 14 UDWDM channels (and one legacy E-PON system) are transmitted simultaneously in a dark-fiber network deployed in the city of Pisa (Italy), delivering real-time and/or test traffic. The trial demonstrated filterless operations (each remote node selects individually its own UDWDM channel on a fine 6.25-GHz grid), real-time GbE transmissions (by using either fully analog or light digital signal processing), multirate transmission (1.25 and 10 Gb/s), high optical distribution network loss (18-40 dB) as well as a bidirectional channel monitoring system.Peer ReviewedPostprint (author's final draft

WDM/TDM PON bidirectional networks single-fiber/wavelength RSOA-based ONUs layer 1/2 optimization

This Thesis proposes the design and the optimization of a hybrid WDM/TDM PON at the L1 (PHY) and L2 (MAC) layers, in terms of minimum deployment cost and enhanced performance for Greenfield NGPON. The particular case of RSOA-based ONUs and ODN using a single-fibre/single-wavelength is deeply analysed. In this WDM/TDM PON relevant parameters are optimized. Special attention has been given at the main noise impairment in this type of networks: the Rayleigh Backscattering effect, which cannot be prevented. To understand its behaviour and mitigate its effects, a novel mathematical model for the Rayleigh Backscattering in burst mode transmission is presented for the first time, and it has been used to optimize the WDM/TDM RSOA based PON. Also, a cost-effective, simple design SCM WDM/TDM PON with rSOA-based ONU, was optimized and implemented. This prototype was successfully tested showing high performance, robustness, versatility and reliability. So, the system is able to give coverage up to 1280 users at 2.5 Gb/s / 1.25 Gb/s downstream/upstream, over 20 Km, and being compatible with the GPON ITU-T recommendation. This precedent has enabled the SARDANA network to extend the design, architecture and capabilities of a WDM/TDM PON for a long reach metro-access network (100 km). A proposal for an agile Transmission Convergence sub-layer is presented as another relevant contribution of this work. It is based on the optimization of the standards GPON and XG-PON (for compatibility), but applied to a long reach metro-access TDM/WDM PON rSOA-based network with higher client count. Finally, a proposal of physical implementation for the SARDANA layer 2 and possible configurations for SARDANA internetworking, with the metro network and core transport network, are presented

WDM-PON Architecture Implement Using AWG with Multicasting Efficiency

ABSTRACT: We present the experimental demonstration of cascaded arrayed waveguide grating (AWG). Here we use the OLT (Optical Layer Termination) has 2 layer stacks. A tuneable one for unicast transmission and another one for multicast transmission. Downstream and upstream data share same optical path. BER curves were measured by using 2.5 GB per sec. data stream in each direction and error free transmission is achieved for downstream and upstream. For this proposed experimental setup is evaluated by using optic system software ver.12