Papers by Christina Politi
Adaptive bit rate variable cost-effective optical networks
2015 17th International Conference on Transparent Optical Networks (ICTON), 2015
This paper provides a high-level overview of network planning and operation processes for lightpa... more This paper provides a high-level overview of network planning and operation processes for lightpath computation in WDM networks. Lightpath demands occur dynamically and the lightpaths are constrained by physical effects. We classify different approaches to connection setup and describe algorithms suitable for this purpose.
We demonstrate a way to apply dynamic networking based on node clustering in real-life core netwo... more We demonstrate a way to apply dynamic networking based on node clustering in real-life core networks and achieve superior performance compared to conventional burst switching techniques in terms of blocking, resource utilization and power consumption.
IEE Proceedings - Optoelectronics, 2005
An optical cross-connect architecture based on wavelength routing is proposed. The design utilise... more An optical cross-connect architecture based on wavelength routing is proposed. The design utilises an input waveband conversion stage followed by an arrayed waveguide grating (AWG) to enable optical switching and an output single wavelength conversion stage for wavelength assignment and regeneration. Arranging the AWG in feedback or foldback loop configuration the requirement for an output multiplexer is eliminated. The proposed solution supports wavelength switching granularity while offering reduced component requirements. Experimental and modelling results indicate very good system performance of the node as the output conversion stage offers regenerating characteristics.
Journal of Optical Communications and Networking, 2009
PAPER Joint Special Section on Recent Progress in Optoelectronics and Communications Header Extraction and Control for an Asynchronous Optical Packet Switch Based on DPSK Decoding
SUMMARY A novel optical header extraction scheme based on optical differential phase shift keying... more SUMMARY A novel optical header extraction scheme based on optical differential phase shift keying—DPSK—decoding is examined analytically and experimentally. The header is applied in front of the payload, on the phase of a pulsed optical level introduced for the duration of the header. The proposed scheme offers maximized header extraction efficiency, re- quired by the electronics to identify the header
2011 13th International Conference on Transparent Optical Networks, 2011
The increasing popularity of converged media services is promoting the deployment of a range of b... more The increasing popularity of converged media services is promoting the deployment of a range of broadband networking technologies aiming at serving the increased bandwidth as well as service portability and user mobility demands. To optimally address the above requirements hybrid access network architectures coupling the benefits of optical (high capacity, robustness) and mobile/wireless networks (extended reach and mobility) are quite promising. In this paper we present the basic steps for converged network design and planning and evaluate algorithms for wireless backhaul optimization based on a PON architecture. Network optimization addresses the capacity requirements per access segment and optical backhaul segment, the physical layer limitations (e.g. power budget) and overall cost (in terms of CAPEX including number of nodes, active ports, civil engineering works etc. and OPEX mainly including real estate and power consumption) by means of both heuristic algorithms and stochastic optimization techniques.
Routing in dynamic future flexi-grid optical networks
2012 16th International Conference on Optical Network Design and Modelling (ONDM), 2012
Routing in dynamic future optical networks will depend on the underlying technology and more spec... more Routing in dynamic future optical networks will depend on the underlying technology and more specifically on whether standard grid or flexi-grid technology will be used. In particular for dynamic flexi-grid networks resource allocation and routing concerns both path establishment and allocation of specific spectrum which in turn relates to the modulation format of the transmitted signals. Moreover if variable bandwidth
<title>Optical packet switch architectures for ultrahigh-speed networks</title>
Optical Transmission, Switching, and Subsystems III, 2005
ABSTRACT
Part of the activities of the ICT EU Network of Excellence "Building the future Optical Network i... more Part of the activities of the ICT EU Network of Excellence "Building the future Optical Network in Europe" (BONE) project is the development of the European Roadmap on Optical Networking in the context of the "Network of the Future". This paper presents a summary of the views of the BONE consortium as they were developed in the framework of the Roadmap activity. The methodology followed in the development of the BONE Roadmap was firstly to identify and analyse the status of broadband access penetration as well as the availability of specific network and IT technologies in various European countries. The data collected were then processed and translated into the traffic volume (distributed across different European countries) that a Pan-European network would need to support. This information is then used as the basis of a WDM optical network dimensioning exercise performed with the aim of identifying the scale of the required optical network. In addition, based on estimations regarding the evolution of broadband access technologies and the degree of broadband penetration and network services and applications, extrapolations regarding the growth of traffic to be supported by the European Network of the Future were made in a systematic manner. These were also used to dimension and understand the requirements of the European Network of the Future. This paper presents the relevant results and also provides a discussion on the BONE consortium views on the Network of the Future from an architectural and technology perspective and an outlook of the relevant key research challenges and possible solutions.
OFC/NFOEC 2007 - 2007 Conference on Optical Fiber Communication and the National Fiber Optic Engineers Conference, 2007
New algorithmically simplified WRA that incorporate physical layer criteria in the path establish... more New algorithmically simplified WRA that incorporate physical layer criteria in the path establishment procedure are suggested and applied in the Deutsche-Telecom network. Their blocking performance superiority and physical performance guarantee are discussed.
Planning and operation of elastic flex-grid optical networks with OFDM variable bandwidth capabilities
2013 15th International Conference on Transparent Optical Networks (ICTON), 2013
ABSTRACT Planning and routing in future elastic optical networks will depend on the underlying te... more ABSTRACT Planning and routing in future elastic optical networks will depend on the underlying technology and more specifically on whether standard grid or flex-grid technology will be used. In particular, for dynamic flex-grid networks, resource allocation and routing concern both path establishment and allocation of specific spectrum, which in turn relates to the modulation format of the transmitted signals. Moreover, if variable bandwidth transponders are utilized simultaneous optimization of allocated spectrum and transponder reach should be performed. In this context, all the above should be integrated in both planning and operation phases of an elastic flex-grid optical network. This paper elaborates on a methodology for integrating design constraints into the planning and operation of elastic optical networks and investigates the benefits of flex-grid technology with variable bandwidth OFDM transponders regarding both the blocking performance and spectral efficiency when compared to their standard-grid counterparts.
Optical Fiber Communication, 2006
A novel algorithm that seeks the 'shortest-widest' path and assigns lightpaths according ... more A novel algorithm that seeks the 'shortest-widest' path and assigns lightpaths according to their Q-factor is developed that exhibits better blocking performance, improved load-balancing and optimum physical performance when compared with 'shortest' path based counterparts.
Photonic Network Communications, 2013
Physical layer impairment aware routing algorithms have been proposed for optical transparent net... more Physical layer impairment aware routing algorithms have been proposed for optical transparent networks in order to calculate the feasibility of dynamically establishing an optical path when no regeneration is used. The benefit of node clustering in optical networks, regarding routing with physical layer impairment awareness, is investigated under the CANON network architecture where regenerators are conveniently placed and routing is confined among a small subset of nodes. The CANON architecture exhibits enhanced blocking performance, high resource utilisation and adequate physical performance; hence, it can serve Quality of Service.
Optics Communications, 2007
The use of a Pump-Suppressed Four Wave Mixing PS-FWM wavelength converter in a wavelength convers... more The use of a Pump-Suppressed Four Wave Mixing PS-FWM wavelength converter in a wavelength conversion and selection switching scheme is examined and demonstrated. The scheme requires a single 2 · 1 Mach Zenhder Interferometer (MZI) and offers substantial pump suppression and efficiency improvement in terms of optical signal-to-noise ratio. Performance measurements on the combination of PS-FWM wavelength converter with an Arrayed Waveguide Grating (AWG) for passive routing, shows the potentially successful use of the scheme in an ultra-fast wavelength routed optical packet switching scheme where the use of optical filters for the separation of the converted signal from the pump is avoided.
Optics Communications, 2007
Optical Crossconnects (OXC) are indispensable for the proliferation of broadband services. Next g... more Optical Crossconnects (OXC) are indispensable for the proliferation of broadband services. Next generation OXCs should be dynamically reconfigurable, to render the optical layer flexible and agile, cost competitive, in order to be a viable alternative to fully electronic solutions and multi-service, i.e. to be able to handle both optical circuits and packets equally well. In this work, an evolutionary migration scenario from semi-static to dynamically reconfigurable broadcast-and-select OXCs is presented. The cornerstone of this approach is modularity in both the node architecture and the corresponding functionality, since these two are inextricably linked. Here, the three evolutionary steps of a modular broadcast-and-select architecture are presented, their principle of operation is explained and their complexity is analyzed. The key building-blocks to implement these OXCs are optical switching elements operating in a gated mode and tunable wavelength converters. Concerning the physical performance of these architectures, an important consideration is that node capacity is traded for higher node cascadeability. This trade-off is studied extensively considering a combination of different switching technologies and optical components. Moreover, the 2R regenerative properties of the all-optical and optoelectronic wavelength converters play a key role in the node cascadeability assessment which is otherwise compromised by OSNR limitations. For this reason, analytical models providing an insight on how certain physical mechanisms are leading to performance degradation are used. The final assessment is made using a commercial simulation tool, allowing the derivation of conclusions for the size of the transparent islands.
Optics Communications, 2007
A quality-of-service (QoS)-aware routing engine for a transparent optical network that accounts f... more A quality-of-service (QoS)-aware routing engine for a transparent optical network that accounts for physical layer impairments (PLI) is presented. PLI are studied collectively by means of Q-factor. The latter is calculated by analytical methods that speed up the calculation and allow application in a dynamic network. Two path establishment algorithms are deployed: the shortest-path and the shortest widest path. The impact of PLI awareness on the QoS is measured in terms of blocking probability and load balance. Any of the physical parameters can be used as an optimization variable in order to assess their effect on performance degradation at system and network level. The impact of the path establishment algorithm on the optimization parameter is analysed.
Journal of Lightwave Technology, 2000
AbstractThis paper presents the results of the optical packet switched network (OPSnet) project,... more AbstractThis paper presents the results of the optical packet switched network (OPSnet) project, which investigated the de-sign of an asynchronous optical packet switch suitable for the core of an optical transport network (OTN). The requirements for the switch were to ...
Journal of Lightwave Technology, 2000
This paper presents views on the future of optical networking. A historical look at the emergence... more This paper presents views on the future of optical networking. A historical look at the emergence of optical networking is first taken, followed by a discussion on the drivers pushing for a new and pervasive network, which is based on photonics and can satisfy the needs of a broadening base of residential, business, and scientific users. Regional plans and targets for optical networking are reviewed to understand which current approaches are judged important. Today, two thrusts are driving separate optical network infrastructure models, namely 1) the need by nations to provide a ubiquitous network infrastructure to support all the future services and telecommunication needs of residential and business users and 2) increasing demands by the scientific community for networks to support their requirements with respect to large-scale data transport and processing. This paper discusses these network models together with the key enabling technologies currently being considered for future implementation, including optical circuit, burst and packet switching, and optical code-division multiplexing. Critical subsystem functionalities are also reviewed. The discussion considers how these separate models might eventually merge to form a global optical network infrastructure.
Journal of Lightwave Technology, 2000
Four wave mixing (FWM) is distinguished from other wavelength conversion techniques by its abilit... more Four wave mixing (FWM) is distinguished from other wavelength conversion techniques by its ability to simultaneously convert a number of input wavelength channels. In this case, optical signal-to-noise ratio (OSNR) is insufficient to describe the performance of the device as many effects are involved. A multiwavelength FWM model is used here to simulate a waveband converter (WBC). The numerical model predicts the waveform of the FWM product. Based on that output, the Q factor of the signal and the power penalty induced to the signal can be calculated to evaluate the performance of such a device. Meanwhile, an analytical model is used for the calculation of the signal power levels and the standard deviation of the fluctuation; hence, it describes the constituent effects-namely, the extinction ratio (ER) degradation, the OSNR degradation, the gain modulation (GM) related crosstalk, and interference. The model's validity is tested against the numerical results. To the best of the authors' knowledge, this is the first time that a numerical model and an analytical model are used to systematically investigate a WBC and to identify the specific effects and derive the design rules. These rules are tested in the experiment. Finally, a tunable WBC (TWBC) based on the dual-pump configuration is described and implemented experimentally.
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Papers by Christina Politi