9 documents found, page 1 of 1
Design/upgrade of a transparent optical network topology resilient to the simul...
Barbosa, Fábio; Sousa, Amaro; Agra, AgostinhoThis paper addresses two related problems in the context of transparent optical networks. In the network design problem, the aim is to identify a set of fiber links to connect a given set of nodes. In the network upgrade problem, the aim is to identify a set of new fiber links to add to a given network topology. For a given fiber length budget, the aim in both problems is to maximize the network resilience to t...
Energy efficient routing for telecommunication networks with multiperiod traffic
Santos, Dorabella; Lopes, C. B.; Sousa, Amaro; Alvelos, Filipe Pereira eThe exponential growth of tra c demand, and supporting network infrastructures, is leading to serious energy consumption issues. With proper routing, some network links can be put on a sleep mode if demands can be routed through other links and, with multiperiod tra c, the sleeping links can change between periods. In this paper, we address the energy e cient routing problem, and we study the tradeo between ene...
Combining column generation and metaheuristics
Alvelos, Filipe Pereira e; Sousa, Amaro; Santos, DorabellaIn this Chapter, we consider the hybridization of column generation (CG) with metaheuristics (MHs) for solving integer programming and combinatorial optimization problems.We describe a general framework entitled ”metaheuristic search by column generation” (for short, SearchCol). CG is a decomposition approach in which one linear programming master problem interacts with subproblems to obtain an optimal solution...
A hybrid column generation with GRASP and path relinking for the network load b...
Santos, Dorabella; Sousa, Amaro; Alvelos, Filipe Pereira eIn this paper, a hybrid meta-heuristic is proposed which combines the GRASP with path relinking method and Column Generation. The key idea of this method is to run a GRASP with path relinking search on a restricted search space, defined by Column Generation, instead of running the search on the complete search space of the problem. Moreover, column generation is used not only to compute the initial restricted s...
Optimizing network load balancing : an hybridization approach of metaheuristics...
Santos, Dorabella; Sousa, Amaro; Alvelos, Filipe Pereira e; Pióro, MichalGiven a capacitated telecommunications network with single path routing and an estimated traffic demand matrix, we aim to determine the routing path of each traffic commodity such that the whole set of paths provide an optimal network load balancing. In a recent paper, we have proposed a column generation based heuristic where, in the first step, we use column generation to solve a linear programming relaxation...
Optimization of link load balancing in multiple spanning tree routing networks
Santos, Dorabella; Sousa, Amaro; Alvelos, Filipe Pereira e; Pióro, MichalIn telecommunication networks based on the current Ethernet technology, routing of traffic demands is based on multiple spanning trees: the network operator configures different routing spanning trees and assigns each demand to be routed in one of the selected spanning trees. A major optimization issue in this solution is the combined determination of (i) a set of appropriate spanning trees, and (ii) assignment...
SearchCol : metaheuristic search by column generation
Alvelos, Filipe Pereira e; Sousa, Amaro; Santos, DorabellaWe propose a general framework for the combination of column generation (CG) with metaheuristics (MHs) aiming to solve combinatorial optimization problems amenable for decomposition approaches, "SearchCol". The combination of the two approaches is based on representing the solution of the problem as the selection of a subset of solutions of smaller (sub)problems which are generated by CG. In each iteration of a...
Traffic engineering of telecommunication networks based on multiple spanning tr...
Santos, Dorabella; Sousa, Amaro; Alvelos, Filipe Pereira eThis paper focuses on tra±c engineering of telecommunica- tion networks, which arises in the context of switched Ethernet networks. It addresses the minimization of the maximum network link load. With the IEEE 802.1s Multiple Spanning Tree Protocol, it is possible to de¯ne multiple routing spanning trees to provide multiple alternatives to route VLAN tra±c demands. Two compact mixed integer linear programming m...
Contribuições da Universidade de Aveiro para a especificação da rede de área lo...
Valadas, Rui; Moreira, Adriano; Lomba, Cipriano; Tavares, António; Moreira, Luís; Oliveira, Carlos; Aguiar, Rui; Sousa, Amaro; Duarte, A. M. de OliveiraThis paper introduces the IEEE 802.11 wireless local area network and describes the main contributions given by the University of Aveiro to its specification.; Este artigo introduz a rede de área local não-cablada IEEE 802.11 e descreve as principais contribuições da Universidade de Aveiro para a sua especificação.