Hitless wavelength assignment in filterless optical access networks

Advantages offered by coherent detection systems in access networks are not limited to the increase of power budget due to the superior sensitivity. Channel selectivity is another intriguing feature offered by coherent systems that can be exploited to enable advanced system and network functionalities for access systems. Among them, we focus here on the implementation of filterless optical networks and network reconfiguration capabilities which might be required to satisfy dynamic load balancing requests and new terminal activations. We show that in the access domain these functionalities do not require DSP-aided coherent receivers, but can be easily realized by means of simpler, fully analogue real-time coherent terminals matching the access network low-cost paradigm. This paper discusses these concepts and how they can be experimentally implemented by using a novel wavelength allocation algorithm and real-time analogue coherent transceivers based on DFB lasers, whose wavelengths are tuned by a simple temperature control

Technologies for Cost-Effective UDWDM-PONs

New technologies for ultradense WDM-PON (udWDM-PON), enabled by coherent techniques and low-cost devices, are developed for an efficient utilization of the optical spectrum, revealing that the 'Wavelength-to-the-User' concept can be feasible. In this paper, an udWDM-PON with only 6.25-GHz channel spacing is implemented with conventional DFB lasers, for a splitter-based PON infrastructure with 256 ONUs. The results of the analysis of udWDM access network architecture with respect to their associated complexity, cost, and migration scenarios, exhibit the potential for higher aggregate throughput, higher split ratios, and node consolidation, when compared to competing technologies

Design of survivable wavelength division multiplexed passive optical networks.

by Chan Tsan Jim.Thesis (M.Phil.)--Chinese University of Hong Kong, 2003.Includes bibliographical references (leaves 68-71).Abstracts in English and Chinese.Chapter Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Introduction --- p.1Chapter 1.2 --- Background --- p.2Chapter 1.2.1 --- Introduction --- p.2Chapter 1.2.2 --- Wavelength Division Multiplexing --- p.3Chapter 1.2.3 --- Arrayed Waveguide Grating --- p.5Chapter 1.2.4 --- Passive Optical Networks --- p.7Chapter 1.3 --- Outline of the thesis --- p.10Chapter Chapter 2 --- Review of Protection and Restoration Schemes --- p.12Chapter 2.1 --- Introduction --- p.12Chapter 2.2 --- Protection Schemes --- p.14Chapter 2.2.1 --- Path Protection --- p.14Chapter 2.2.2 --- Link Protection --- p.16Chapter 2.3 --- Restoration Schemes --- p.17Chapter 2.3.1 --- Path Restoration --- p.17Chapter 2.3.2 --- Link Restoration --- p.18Chapter 2.4 --- Protection and Restoration Schemes in PON --- p.18Chapter 2.4.1 --- Protection Schemes in G.983.1 --- p.18Chapter 2.4.2 --- Other Proposed Schemes --- p.21Chapter Chapter 3 --- Design of WDM PON Network Architecture --- p.26Chapter 3.1 --- Introduction --- p.26Chapter 3.2 --- The Group Protection Architecture (GPA) --- p.27Chapter 3.2.1 --- Network Design --- p.27Chapter 3.2.2 --- Protection Mechanism --- p.28Chapter 3.2.3 --- Wavelength Assignments --- p.30Chapter 3.2.4 --- Power Budget Calculation --- p.32Chapter 3.2.5 --- Crosstalk Analysis --- p.33Chapter 3.2.6 --- Discussion --- p.35Chapter 3.3 --- The Enhanced Group Protection Architecture (EGPA) --- p.36Chapter 3.3.1 --- Introduction --- p.36Chapter 3.3.2 --- Network Design --- p.37Chapter 3.3.3 --- Protection Mechanism --- p.38Chapter 3.3.4 --- Wavelength Assignments --- p.39Chapter 3.3.5 --- Power Budget Calculation --- p.40Chapter 3.3.6 --- Crosstalk Analysis --- p.41Chapter 3.3.7 --- Discussion --- p.42Chapter 3.4 --- The Hybrid Ring Architecture (HR) --- p.42Chapter 3.4.1 --- Introduction --- p.42Chapter 3.4.2 --- Network Design --- p.43Chapter 3.4.3 --- Protection Mechanism --- p.44Chapter 3.4.4 --- Wavelength Assignments --- p.45Chapter 3.4.5 --- Power Budget Calculation --- p.46Chapter 3.4.6 --- Crosstalk Analysis --- p.47Chapter 3.4.7 --- Discussion --- p.47Chapter 3.5 --- Comparison of the three schemes --- p.48Chapter 3.6 --- Summary of the three schemes --- p.50Chapter Chapter 4 --- Experimental Evaluation --- p.51Chapter 4.1 --- Introduction --- p.51Chapter 4.2 --- Experimental Setup --- p.51Chapter 4.2.1 --- The GPA Scheme --- p.51Chapter 4.2.2 --- The EGPA Scheme --- p.53Chapter 4.2.3 --- The HR Scheme --- p.54Chapter 4.3 --- Experimental Result --- p.55Chapter 4.3.1 --- Optical Spectrum --- p.55Chapter 4.3.2 --- Transmission Performance --- p.58Chapter 4.3.3 --- Switching/Restoration Time --- p.61Chapter 4.3.4 --- Crosstalk Penalty --- p.63Chapter 4.4 --- Conclusion --- p.64Chapter Chapter 5 --- Conclusion and Future Works --- p.65Chapter 5.1 --- Introduction --- p.65Chapter 5.2 --- Conclusion --- p.65Chapter 5.3 --- Future Works --- p.66References --- p.6

Redes de acceso UDWDM operadas con láseres aleatorios de sintonía limitada

A new passive optical network (PON) for access, making use of ultra-dense wavelength division multiplexing (UDWDM) by densely spacing channels by a few gigahertz and introducing the "wavelength-to-the-user" concept, is proposed in this thesis. The key challenge will be developing low-cost coherent transceivers that provide an excellent selectivity while avoiding optical filters and furnishing high sensitivity, which will allow high splitting ratios, large numbers of users, and long-distance reach. The optical distribution network (ODN) at the outside plant is based on splitters and is kept compatible with legacy systems. Optical network unit (ONU) designs realized with coherent transceivers using one or two lasers are presented. Employing a unique laser diode as transmitter and receiver local oscillator at the ONU to realize a cheap terminal implies to use the same wavelength for both up and down directions; therefore, in Full-Duplex (FD) transmission mode the Rayleigh Backscattering (RB) crosstalk will drastically perturb the reception. In this thesis, a Half-Duplex (HD) solution to avoid the RB disturbance is proposed and analyzed in different scenarios of reach and splitting ratios. Moreover, using Full-Duplex solutions, different spectral band channel structures are presented and adapted to the diverse transceivers options and laser selections. Two optical line terminal (OLT) architectures are introduced, a classical splitting-based structure and a new AWG-based structure, with two interleaving AWGs with no blocking channel features and lower insertions losses. The new structure allows saving the optical amplification in networks with a modest number of users and/or reach. The ONUs at the customer premises have lasers with limited thermal tunability, and their wavelengths are randomly distributed in a band. To avoid full-tunable lasers, static and dynamic wavelength assignment paradigms (SWA and DWA) and heuristic assignment schemes for spectrum management are proposed, simulated, and compared. By using the heuristic static and dynamic wavelength assignment schemes, the required optical band is obtained and optimized. In activation processes, ONU acceptances up to 99.9% are achieved. The PON is dimensioned according to the number of deployed users and system reach; moreover, power safety and fiber nonlinearity constraints are evaluated, illustrating the characteristics of the projected network. Furthermore, in operation scenarios under indoor (soft) and also under outdoor (harsh) environmental conditions, ONU blocking probabilities below 0.1% and ONU availability ratios (OARs) up to 99.9% are demonstrated modifying the heuristic schemes developed previously and extending the original working band. As the laser tuning and temperature stabilization are achieved by heating or cooling control, and the power consumption varies depending on the wavelength position in a tuning window and environmental conditions. The power consumption of the developed DWA schemes under different environmental condition scenarios in the network are evaluated and compared, since energy efficiency is important to reduce the green-house gas emissions. Finally, activation process taking account the different spectral band structures, DWA schemes and transceivers are proposed.Una nova xarxa d'accés òptica i passiva (PON) és desenvolupada usant multiplexors per longitud d'ona ultra densa (UDWDM) mitjançant una separació del canals de pocs gigahertzs i introduint el concepte d'una longitud d'ona per usuari és proposat en aquesta tesis. El repte clau serà aconseguir desenvolupar transceptors coherents de baix cost que aporten una excel·lent selectivitat, evitant els filtres òptics, i a més a més gran sensibilitat, el que permetrà grans ràtios als divisors de potència, gran nombre d'usuaris i grans àrees de cobertura.La xarxa de distribució òptica (ODN) a la planta externa serà basada en divisor de potència i serà compatible amb els sistemes actuals. Dissenys del equipament d'usuari (ONU) amb transceptors coherents i amb un o dos làsers són presentats.Utilitzar un únic díode làser com a transmissor i oscil·lador local del receptor a la ONU per realitzar un terminal barato implicarà usar la mateixa longitud en tots dos sentits, de pujada i baixada, per tant, en una transmissió en mode Full-Duplex (FD) la diafonia provocada per la dispersió de Rayleigh (RB) pertorbarà dràsticament la recepció. En aquesta tesis és proposat i estudiat una solució Half-Duplex (HD) per a evitar l'alteració produïda per RB i és analitzada en diferents escenaris de cobertura i ràtios en los divisor de potència.Usant solucions Full-Duplex, diferents estructures de bandes espectrals en los canals són presentades, adaptades a les diverses opcions de transceptors i a les seleccions de làsers.Dues arquitectures per a l'equipament terminal de línia (OLT) són introduïdes, una estructura clàssica basada en divisors de potència i una nova estructura basada en AWGs, amb dos AWGs entrellaçat, que permet utilitzar tots els canals i presentar menys pèrdues d'inserció. Aquesta nova estructura permet estalviar l'amplificació òptica en xarxes amb un nombre modest d'usuaris i/o àrees de cobertura.Les ONUs a les instal·lacions de l'usuari tenen làsers sintonitzables tèrmicament i les seves longituds d'ona són distribuïdes aleatòriament dins d'una banda. Per a evitar l'ús de làsers completament sintonitzables, metodologies d'assignació de longitud d'ona dinàmics i estàtics, juntament amb esquemes heurístics per la gestió de l'espectre són proposats, simulats y comparats.Mitjançant l'ús dels esquemes d'assignació de longitud d'ona heurístics, tant estàtics com dinàmics, és obtinguda la banda òptica necessària i optimitzada. Durant el procés d'activació és aconseguit un índex d'acceptació del 99.9% .D'acord amb el nombre d'usuaris i l'àrea de cobertura s'ha dimensionat la PON, a més a més, les restriccions per motius de seguretat i no linealitats a la fibra són avaluats, il·lustrant les característiques del projecte de xarxa.Tot seguit, en una escenari d'operació baix condicions ambientals, tan interior (suaus), com exteriors (severes), probabilitats de bloqueig inferiors a 0.1% i ràtios de disponibilitat (OAR) de dels ONUs del 99.9% són demostrades modificant els esquemes heurístics desenvolupats anteriorment i estenent les bandes de treball originals.Com la sintonia del làser i la seva estabilització en temperatures són aconseguides amb un sistema de control, escalfant i refredant, la potència consumida varia depenent de la posició dins la finestra de sintonia i de les condicions ambientals. La potència consumida, baix diferents condicions ambientals, per l'ús dels esquemes DWA en la xarxa són avaluats, ja que l'eficiència energètica és important per a reduir els gasos d'efecte hivernacle.Finalment, processos d'activació tenint en compte les diferents estructures de bandes espectrals, DWA esquemes i transceptors són propostes.Postprint (published version

Software Defined Applications in Cellular and Optical Networks

abstract: Small wireless cells have the potential to overcome bottlenecks in wireless access through the sharing of spectrum resources. A novel access backhaul network architecture based on a Smart Gateway (Sm-GW) between the small cell base stations, e.g., LTE eNBs, and the conventional backhaul gateways, e.g., LTE Servicing/Packet Gateways (S/P-GWs) has been introduced to address the bottleneck. The Sm-GW flexibly schedules uplink transmissions for the eNBs. Based on software defined networking (SDN) a management mechanism that allows multiple operator to flexibly inter-operate via multiple Sm-GWs with a multitude of small cells has been proposed. This dissertation also comprehensively survey the studies that examine the SDN paradigm in optical networks. Along with the PHY functional split improvements, the performance of Distributed Converged Cable Access Platform (DCCAP) in the cable architectures especially for the Remote-PHY and Remote-MACPHY nodes has been evaluated. In the PHY functional split, in addition to the re-use of infrastructure with a common FFT module for multiple technologies, a novel cross functional split interaction to cache the repetitive QAM symbols across time at the remote node to reduce the transmission rate requirement of the fronthaul link has been proposed.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201