Channel allocation in elastic optical networks using traveling salesman problem algorithms

Elastic optical networks have been proposed to support high data rates in metro and core networks. However, frequency allocation of the channels (i.e., channel ordering) in such networks is a challenging problem. This requires arranging the optical channels within the frequency grid with the objective of ensuring a minimum signal-to-noise ratio (SNR). An optimal arrangement results in the highest SNR margin for the entire network. However, determining the optimal arrangement requires an exhaustive search through all possible arrangements (permutations) of the channels. The search space increases exponentially with the number of channels. This discourages an algorithm employing an exhaustive search for the optimal frequency allocation. We utilize the Gaussian noise (GN) model to formulate the frequency allocation (channel ordering) problem as a variant of the traveling salesman problem (TSP) using graph theory. Thereafter, we utilize graph-theoretic tools for the TSP from the existing literature to solve the channel ordering problem. Performance figures obtained for the proposed scheme show that it is marginally inferior to the optimal search (through all possible permutations) and outperforms any random allocation scheme. Moreover, the proposed scheme is implementable for a scenario with a large number of channels. In comparison, an exhaustive search with the GN model and split-step Fourier method simulations are shown to be feasible for a small number of channels only. It is also illustrated that the SNR decreases with an increase in bandwidth when the frequency separation is high

Routing and Spectrum Allocation in Spectrum-Sliced Elastic Optical Path Networks: A Primal-Dual Framework

The recent decade has witnessed a tremendous growth of Internet traffic, which is expected to continue climbing for the foreseeable future. As a new paradigm, Spectrum-sliced Elastic Optical Path (SLICE) networks promise abundant (elastic) bandwidth to address the traffic explosion, while bearing other inherent advantages including enhanced signal quality and extended reachability. The fundamental problem in SLICE networks is to route each traffic demand along a lightpath with continuously and consecutively available sub-carriers, which is known as the Routing and Spectrum Allocation (RSA) problem. Given its NP-Hardness, the solutions to the RSA problem can be classified into two categories: optimal solutions using link-based, path-based, and channel-based Integer Linear Programming (ILP) models, which require extensive computational time; and sub-optimal heuristic and meta-heuristic algorithms, which have no guarantee on the solution quality. In this work, inspired by a channel-based ILP model, we propose a novel primal-dual framework to address the RSA problem, which can obtain a near-optimal solution with guaranteed per-instance closeness to the optimal solution

Models of vertical interconnection in the future internet networks

Interkonekcija, čiji primarni cilj je omogućavanje korisnicima jednog učesnika na tržištu telekomunikacija da komuniciraju sa korisnicima drugog učesnika, odnosno, obezbeđivanje pristupa servisima koje obezbeđuje drugi učesnik, javila se nakon liberalizacije tržišta telekomunikacija. Vertikalna interkonekcija predstavlja fizičko i logičko povezivanje učesnika na različitim nivoima mreže. U okruženju budućeg Interneta, sagledavanje tehničko-ekonomskih aspekata interkonekcije predstavlja pitanje od izuzetnog značaja. U opštem slučaju, učesnici u vertikalnoj interkonekciji u okruženju budućeg Interneta mogu biti provajderi sadržaja i aplikacija, provajderi Internet servisa, Content Delivery Network (CDN) provajderi i cloud provajderi. Pojava Cloud Computing-a uvela je značajne promene u Internet okruženju koje se pre svega odnose na mogućnost pristupa skalabilnim i deljivim, fizičkim ili virtuelnim resursima. Na taj način, stvara se elastična platforma koja obezbeđuje dinamičnu i jednostavnu skalabilnost, pojednostavljuje se obezbeđivanje infrastrukture i omogućava se unapređenje performansi. Razvoj servisa i aplikacija zahtevnih u pogledu propusnog opsega praćen širom implementacijom Cloud Computing-a utiče na kontinuiran rast Internet saobraćaja, što zahteva primenu tehnologija koje mogu zadovoljiti sve strože zahteve. Kao rešenje za transportni nivo mreže, razvijene su elastične optičke mreže koje mogu obezbediti dovoljne propusne opsege uz efikasno iskorišćenje spektra. Imajući u vidu promene koje prate razvoj okruženja budućeg Interneta, kao i značaj vertikalne interkonekcije, neophodno je razmotriti i jasno definisati tehničko-ekonomske relacije između učesnika u budućem Internetu, što je predmet istraživanja ove doktorske disertacije. U okviru disertacije predložen je model koji ima za cilj određivanje adekvatnog ugovora o interkonekciji između učesnika u vertikalnoj interkonekciji, i to provajdera sadržaja i aplikacija i provajdera Internet servisa u procesu obezbeđivanja sadržaja krajnjim korisnicima, uz mogućnost parcijalne migracije sadržaja na resurse cloud provajdera. Analiza obuhvata različite ugovore o interkonekciji i određuje adekvatan ugovor, u zavisnosti od ciljnih profita provajdera koji učestvuju u vertikalnoj interkonekciji i prihvatljive stope odbijenih zahteva za obezbeđivanje sadržaja krajnjim korisnicima. Data analiza je proširena istraživanjem adekvatnog mehanizma tarifiranja i alokacije resursa cloud provajdera. Predložen je nov, hibridni model pristupa resursima cloud provajdera koji obezbeđuje zadovoljavajuće rezultate u kontekstu minimizacije troškova i minimizacije stope odbijenih zahteva za pristup sadržajima...Interconnection, whose primary aim is enabling communication between end users of different undertakings, i.e. enabling access to the other undertaking's services, was introduced after the telecommunication market liberalization. Vertical interconnection represents the physical and logical linking of the undertakings on different network levels. Consideration of technical and economic aspects of the interconnection is a crucial issue in the future Internet environment. In general, undertakings in vertical interconnection in the future Internet environment include content and application providers, Internet service providers, Content Delivery Network (CDN) providers and Cloud providers. The development of Cloud Computing introduced significant changes in the Internet environment in terms of enabling access to scalable and shareable, physical or virtual resources. Therefore, the elastic platform for dynamic and simple scalability is enabled, the access to infrastructure is simplified and performances are improved. High bandwidth demanding services and applications, along with the wide adoption of Cloud Computing causes permanent growth of Internet traffic. This indicates that the introduction of new technologies, capable to satisfy high bandwidth requirements, is necessary. Elastic optical networks are proposed as a promising solution for transport networks. These networks provide enough bandwidth, along with high efficiency in spectrum utilization. Forasmuch changes in the future Internet environment and the importance of the vertical interconnection, it is mandatory to consider and properly define technical and economic relations between undertakings in the future Internet environment, which is the research subject of this doctoral dissertation. Within dissertation, a model for the determination of a proper interconnection agreement between undertakings in the vertical interconnection, content and application provider and an Internet service provider, in the content provisioning process with partial cloud migration is proposed. The analysis comprises different interconnection agreements and determines appropriate agreement, depending on the targeted providers' profits and satisfying requests' for content provisioning rejection rate. This analysis is extended to determine adequate pricing and allocation mechanism for cloud provider's resources. A new, hybrid model for enabling access to cloud resources is proposed. The model provides satisfying results in terms of the costs' minimization and the minimization of requests' rejection rate..

Calibración de un algoritmo de detección de anomalías marítimas basado en la fusión de datos satelitales

La fusión de diferentes fuentes de datos aporta una ayuda significativa en el proceso de toma de decisiones. El presente artículo describe el desarrollo de una plataforma que permite detectar anomalías marítimas por medio de la fusión de datos del Sistema de Información Automática (AIS) para seguimiento de buques y de imágenes satelitales de Radares de Apertura Sintética (SAR). Estas anomalías son presentadas al operador como un conjunto de detecciones que requieren ser monitoreadas para descubrir su naturaleza. El proceso de detección se lleva adelante primero identificando objetos dentro de las imágenes SAR a través de la aplicación de algoritmos CFAR, y luego correlacionando los objetos detectados con los datos reportados mediante el sistema AIS. En este trabajo reportamos las pruebas realizadas con diferentes configuraciones de los parámetros para los algoritmos de detección y asociación, analizamos la respuesta de la plataforma y reportamos la combinación de parámetros que reporta mejores resultados para las imágenes utilizadas. Este es un primer paso en nuestro objetivo futuro de desarrollar un sistema que ajuste los parámetros en forma dinámica dependiendo de las imágenes disponibles.XVI Workshop Computación Gráfica, Imágenes y Visualización (WCGIV)Red de Universidades con Carreras en Informática (RedUNCI