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Single PON network design with unconstrained splitting stages
Gouveia, Luís; Lopes, Maria João; Sousa, Amaro Fernandes deA Passive Optical Network (PON) is a network technology for deploying access networks based on passive optical components. In a single PON access network, the client terminals are connected to a Central Office through optical splitters and interconnecting fibers where each splitter splits in equal parts the input optical signal coming from the Central Office over its different output fibers. In this paper, we c...
Spanning trees with variable degree bounds
Gouveia, Luís; Moura, Pedro; Ruthmair, Mario; Sousa, Amaro Fernandes deIn this paper, we introduce and study a generalization of the degree constrained minimum spanning tree problem where we may install one of several available transmission systems (each with a different cost value) in each edge. The degree of the endnodes of each edge depends on the system installed on the edge. We also discuss a particular case that arises in the design of wireless mesh networks (in this variant...
Design cost and spectrum efficiency comparison of fixed-grid and flex-grid opti...
Sousa, Amaro Fernandes de; Lopes, Carlos Borges; Monteiro, PauloThis paper deals with the design of optical networks aiming to minimize the design cost and the spectrum usage. We present an optimization method that is able to find the optimal solutions of relevant sized instances. We apply the method to realistic case studies. With the obtained solutions, we make a cost and spectrum efficiency comparison analysis between fixed-grid and flex-grid optical networks. The result...
A testbed for developing, simulating and experimenting multipath aggregation al...
Rico, Fábio; Fonseca, Pedro; Sousa, Amaro Fernandes deToday, electronic devices may have multiple possibilities to communicate, either through wired or wireless interfaces. Despite this diversity, devices still fail to fully use the available resources by not simultaneously using multiple channels to their full extent. This is especially true in wireless channels where the efficient aggregation of multiple channels has proved to be a difficult task, as shown in re...
A hybrid column generation with GRASP and path relinking for the network load b...
Santos, Dorabella; Sousa, Amaro Fernandes de; Alvelos, FilipeIn 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...
Load balancing optimization of telecommunication networks with two differentiat...
Sousa, Amaro Fernandes de; Lopes, Carlos; Santos, DorabellaThe Differentiated Services architecture is a scalable solution to provide differentiated Quality of Service. In this paper, we address the network load balancing optimization of such networks based on bandwidth differentiation between two services. We define the optimization problem as an Integer Programming model and propose a heuristic algorithm based on GRASP with Path Relinking. We present computational re...
Optimizing network load balancing: an hybridization approach of metaheuristics ...
Santos, Dorabella; Sousa, Amaro Fernandes de; Alvelos, Filipe; 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...
Network admission control solution for 6LoWPAN networks
Oliveira, Luís; Rodrigues, Joel; Neto, Carlos; Sousa, Amaro Fernandes deWireless sensor networks (WSNs) are a technology with high potential to be employed in several industrial and quotidian situations. Self-organization and self configuration are key characteristics of WSNs. In most situations, these characteristics are useful because they minimize the configuration efforts and simultaneously increase the network robustness in case of failures or topology changes. However, they c...
Algorithms in the deployment of Optical Transport Networks
Monteiro, Paulo; Sousa, Amaro Fernandes de; Ribeiro, Marco; Trota, Tiago; Sahin, GokhanWe propose a multi-thread multi-start local search strategy to optimize the cost of the next generation of Optical Transport Networks (OTNs) in the presence of heterogeneous client demands and considering a wide range of engineering solutions and constraints whose combination is hard to address, such as flexible grid frequency assignment, single and multi-hop grooming, regenerator placement and inverse-multiple...
A network access control framework for 6LoWPAN networks
Oliveira, Luís Miguel Lopes de; Rodrigues, Joel; Sousa, Amaro Fernandes de; Lloret, JaimeLow power over wireless personal area networks (LoWPAN), in particular wireless sensor networks, represent an emerging technology with high potential to be employed in critical situations like security surveillance, battlefields, smart-grids, and in e-health applications. The support of security services in LoWPAN is considered a challenge. First, this type of networks is usually deployed in unattended environm...