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Klinkowski M.,National Institute of Telecommunications | Ruiz M.,Polytechnic University of Catalonia | Velasco L.,Polytechnic University of Catalonia | Careglio D.,Polytechnic University of Catalonia | And 2 more authors.
IEEE Journal on Selected Areas in Communications | Year: 2013

Elastic flexgrid optical networks (FG-ON) are considered a very promising solution for next-generation optical networks. In this article we focus on lightpath adaptation under variable traffic demands in FG-ON. Specifically, we explore the elastic spectrum allocation (SA) capability of FG-ON and, in this context, we study the effectiveness of three alternative SA schemes in terms of the network performance. To this end, we formulate a Multi-Hour Routing and Spectrum Allocation (MH-RSA) optimization problem and solve it by means of both Integer Linear Programming (ILP) and efficient heuristic algorithms. Since, as numerical results show, the effectiveness of SA schemes highly depends on the traffic demand profile, we formulate some indications on the applicability of elastic SA in FG-ON. © 2012 IEEE.

Klinkowski M.,National Institute of Telecommunications | Walkowiak K.,Wroclaw University of Technology
IEEE Communications Letters | Year: 2011

A spectrum-sliced elastic optical path network (SLICE) architecture has been recently proposed as an efficient solution for a flexible bandwidth allocation in optical networks. In SLICE, the problem of Routing and Spectrum Assignment (RSA) emerges. In this letter, we both formulate RSA as an Integer Linear Programming (ILP) problem and propose an effective heuristic to be used if the solution of ILP is not attainable. © 2011 IEEE.

Jaroszewicz S.,National Institute of Telecommunications
Data Mining and Knowledge Discovery | Year: 2010

The paper presents a method of interactive construction of global Hidden Markov Models (HMMs) based on local sequence patterns discovered in data. The method is based on finding interesting sequences whose frequency in the database differs from that predicted by the model. The patterns are then presented to the user who updates the model using their intelligence and their understanding of the modelled domain. It is demonstrated that such an approach leads to more understandable models than automated approaches. Two variants of the problem are considered: mining patterns occurring only at the beginning of sequences and mining patterns occurring at any position; both practically meaningful. For each variant, algorithms have been developed allowing for efficient discovery of all sequences with given minimum interestingness. Applications to modelling webpage visitors behavior and to modelling protein secondary structure are presented, validating the proposed approach. © 2010 The Author(s).

Klinkowski M.,National Institute of Telecommunications | Walkowiak K.,Wroclaw University of Technology
IEEE Network | Year: 2013

This article provides motivation for the elastic optical network (EON) approach, an efficient and cost-effective solution for provisioning of cloud computing traffic. As opposed to wavelength switched optical networks (WSONs), the capabilities of which are limited by the use of rigid frequency grids, EON architectures allow for both scalable bandwidth provisioning and flexible resource allocation. The deployment cost, energy consumption, and bandwidth usage for both EON and classical WSON transport networks are compared in pan-European and U.S. backbone networks for 2012¿2020 using Cisco traffic predictions. Results show that the EON concept significantly outperforms WSON in all examined criteria, and the gap between the two architectures increases in subsequent years. Moreover, potential advantages of anycast routing in transport networks with data center traffic are demonstrated. © 1986-2012 IEEE.

Mongay Batalla J.,National Institute of Telecommunications | Krawiec P.,National Institute of Telecommunications
Personal and Ubiquitous Computing | Year: 2014

This paper proposes a novel architecture of the ID (IDentifier) layer for Internet of Things, which is embedded in the network level instead of traditional overlay solutions. Our contribution characterizes development of human-readable, hierarchical ID-based unified addressing for both objects and services, corresponding to their locations. In this way, users gain easier access to the IoT resources and native support for multicast. Furthermore, we take advantage of the Networking Named Content approach to specify rules for ID-based data transfer. The network nodes have capabilities to cache forwarded data for handling future requests, what may decrease network overload and facilitate cooperation between applications and sensors which periodically move into sleep mode for saving energy. ID-based routing offers decoupling of identification of objects/services from their location. Awareness of forwarded IoT data together with hierarchical distribution of the network makes feasible the local management of users and objects, that is, the essential IoT processes such as object/service registration, publication, searching and resolution can be managed locally in the network node. This offers high flexibility and manageability and improves response of the system when the number of handled things scales. The paper presents the architecture of the proposed solution for ID layer focusing on modules and mechanisms of the ID network node, as well as detailed description of registration, resolution and forwarding processes. Furthermore, the implementation of the system, performed on Linux-based routers, was tested to confirm the correctness of ID layer processes. The tests show that the performance of ID network node is not worse than the performance of a classical IP Linux router running on an identical physical device. © 2013 The Author(s).

Klinkowski M.,National Institute of Telecommunications
Advances in Intelligent Systems and Computing | Year: 2013

In this work we address the problem of static Routing and Spectrum Assignment (RSA) in a flexible grid optical network with dedicated path protection consideration. Since RSA is a difficult problem, we make use of the Genetic Algorithm (GA) metaheuristic to provide near-optimal solutions to the problem. We investigate the effectiveness of GA for a set of network scenarios. Evaluation results show that the proposed algorithm outperforms reference algorithms from the literature. © 2013 Springer-Verlag Berlin Heidelberg.

Osuch T.,National Institute of Telecommunications
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2016

The influence of the complex interference patterns created by a phase mask with variable diffraction efficiency in apodized fiber Bragg grating (FBGs) formation on their reflectance spectra is studied. The effect of the significant contributions of the zeroth and higher (m > ±1) diffraction orders on the Bragg wavelength peak and its harmonic components is analyzed numerically. The results obtained for Gaussian and tanh apodization profiles are compared with similar data calculated for a uniform grating. It is demonstrated that when an apodized FBG is written using a phase mask with variable diffraction efficiency, significant enhancement of the harmonic components and a reduction of the Bragg wavelength peak in the grating spectral response are observed. This is particularly noticeable for the Gaussian apodization profile due to the substantial contributions of phase mask sections with relatively small phase steps in the FBG formation. © 2016 Optical Society of America.

Zinenko T.L.,Ukrainian Academy of Sciences | Marciniak M.,National Institute of Telecommunications | Marciniak M.,Kielce University of Technology | Nosich A.I.,Ukrainian Academy of Sciences
IEEE Journal on Selected Topics in Quantum Electronics | Year: 2013

We study the plane wave scattering and absorption by a flat grating of thin silver nanostrips located in free space, in the visible-light range. The formulation involves generalized boundary conditions imposed on the strip median lines. We use an accurate numerical solution to this problem based on the dual-series equations and the method of analytical regularization. This guarantees fast convergence and controlled accuracy of computations. Reflectance, transmittance, and absorbance as a function of the wavelength and the grating parameters are analyzed. In addition to well-known surface-plasmon resonances, sharp resonances are revealed in the H-polarized scattering near but not equal to the Rayleigh wavelengths of nonzero diffraction orders; in the E-polarized scattering these resonances are not visible. Asymptotic formulas for the frequencies and natural fields of the grating resonances are presented. © 1995-2012 IEEE.

Struzak R.,National Institute of Telecommunications
IEEE Communications Magazine | Year: 2010

This article provides an analysis of broadband Internet diffusion in 27 countries of the European Union. It proposes a simple model of its growth and identifies the theoretical growth limits in each country. Some aspects of the European i2010 project implementation are presented, discussed, and compared with the model. Comments on bottlenecks and major barriers in the broadband Internet diffusion process are also offered. The existing digital gaps are irreducible in some cases and will exist as long as the current development conditions continue. The approach and analysis method proposed here may be useful in examining limits of other services or in other regions during the planning, design, implementation, and performance tracking stages of existing or new services. © 2010 IEEE.

Klinkowski M.,National Institute of Telecommunications
Cybernetics and Systems | Year: 2013

Elastic optical network (EON) architectures are a very promising solution for next generation optical networks. In EON, a basic problem in network design and operation is the problem of routing and spectrum allocation (RSA). In this work, we focus on RSA in a survivable EON with dedicated path protection (DPP) consideration. Because RSA is a difficult problem itself, we develop an evolutionary algorithm (EA) with the aim to support the search for optimal solutions. We investigate the effectiveness of the algorithm for a set of survivable network scenarios. Evaluation results show that the proposed algorithm outperforms reference algorithms from the literature. Copyright © 2013 Taylor & Francis Group, LLC.

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