System of Systems Architecting Problems: Definitions, Formulations, and Analysis

The system of systems architecting has many applications in transportation, healthcare, and defense systems design. This study first presents a short review of system of systems definitions. We then focus on capability-based system of systems architecting. In particular, capability-based system of systems architecting problems with various settings, including system flexibility, fund allocation, operational restrictions, and system structures, are presented as Multi-Objective Nonlinear Integer Programming problems. Relevant solution methods to analyze these problems are also discussed

Wide area telecommunication network design: Application to the Alberta SuperNet

This article proposes a solution methodology for the design of a wide area telecommunication network. This study is motivated by the Alberta SuperNet project, which provides broadband Internet access to 422 communities across Alberta. There are two components to this problem: the network design itself, consisting of selecting which links will be part of the solution and which nodes should house shelters; and the loading problem which consists of determining which signal transport technology should be installed on the selected edges of the network. Mathematical models are described for these two subproblems. A tabu search algorithm heuristic is developed and tested on randomly generated instances and on Alberta SuperNet data. © 2008 Operational Research Society Ltd. All rights reserved

Planification du réseau d'accès pour l'amélioration de la rentabilité de l'infrastructure d'un réseau FTTN

RÉSUMÉ Étant donné l’offre de nouveaux services de réseau comme la télévision haute définition sur le protocole IP (Internet Protocol), de nouvelles architectures et technologies devraient être planifiées et introduites dans le réseau d’accès afin d’améliorer le taux d’accès. La meilleure solution est d’étendre le réseau de fibre jusqu’à l’abonné. Cependant, celle-ci est très coûteuse et ne peut être largement déployée de nos jours. Une alternative intéressante est la technologie FTTN (Fiber-to-the-node) qui réduit la portion de réseau utilisant le cuivre. Dans ce mémoire, on commence par présenter un modèle de programmation mathématique de réseau d’accès dans le but d’améliorer la rentabilité de l’infrastructure d’un réseau FTTN. Ce modèle consiste à trouver le nombre et la localisation des noeuds, et sélectionner les chemins qui seront utilisés d’un noeud à chaque point de demande. Le problème a des contraintes qui limitent la capacité des noeuds et la distance entre chaque point de demande et le noeud qui le dessert. Le but est de minimiser la somme du coût des paires de cuivre à installer et du coût d’installation des noeuds. Par la suite, la complexité du problème est analysée. Nous montrons que des instances du problème de grande taille ne peuvent être résolues de manière exacte dans un temps raisonnable, car le problème est NP-difficile. Nous proposons donc une heuristique basée sur la recherche taboue dans le but de trouver de bonnes solutions dans un temps raisonnable. Les résultats obtenus en utilisant l'heuristique taboue proposée sont comparés avec une borne inférieure obtenue en relâchant des contraintes du modèle mathématique. Celle-ci est calculée en utilisant le résolveur commercial CPLEX qui utilise l'algorithme d'évaluation et séparation. Des tests effectués avec des exemplaires du problème générés de façon aléatoire montrent que l'heuristique proposée donne des résultats satisfaisants. En effet, la moyenne des écarts est de 0,34 et le temps d'exécution est raisonnable.----------ABSTRACT Considering the introduction of new Internet Protocol (IP) services, new architecture and network technologies should be designed and introduced for the access network to improve the access rate. Actually, the best solution is to extend the fiber network and use the fiber-to-the-home (FTTH) architecture. However, this solution is still too costly and cannot be widely deployed. An interesting alternative is the fiber-to-the-node (FTTN) architecture, which reduces the copper portion of the access network. In this document, an integer mathematical programming model is proposed for the access network design in order to improve the profitability of the FTTN infrastructure. It consists in finding the number and the location of the nodes, and selecting the way each point of demand will be connected with the node that is assigned to serve it. The problem has constraints that limit the nodes capacity and the distance between each point of demand and the node that is assigned to serve it. The goal is to minimise the cost of deploying the copper links and the cost of setting the nodes. The problem complexity will then be analysed. We show that large problem instances cannot be solved to the optimum in a reasonable amount of time because the problem is NP-hard. Next, we propose a heuristic based on the tabu search to find good solutions. The results of the tabu heuristic are compared to a lower bound found by solving a relaxed version of the model with CPLEX that uses the branch-and-bound algorithm. The heuristic was tested with randomly generated instances of the problem. The results show that the proposed heuristic finds good quality solutions

Nodal distribution strategies for designing an overlay network for long-term growth

Scope and Method of Study:This research looked at nodal distribution design issues associated with building an overlay network on top of an existing legacy network with overlay network switches and links not necessarily matching the switch and link locations of the underlying network. A mathematical model with two basic components, switch costs and link costs, was developed for defining the total cost of a network overlay. The nature of the underlying legacy topology determines the dominant factor, link or switch costs to the total cost function as well as the unit cost for switches and links.Findings and Conclusions:The three design heuristics presented first, locate overlay switches at nodes in the center of the legacy network as opposed to the periphery; second, locate overlay switches at legacy nodes with high connectivity; and third, locate overlay switches at legacy nodes with high traffic flow demands, can be used to help point to the direction of keeping costs under control when design changes are required. Applying the concept of efficient frontiers to the world of network design and building a suite of best designs gives the network designer greater insight into how to design the best network in the face of changing real-world constraints. For the cost model and the case studies evaluated using the design strategies in this study, distributed approaches generally tend to be a good choice when the link costs dominate the total cost function because total path distances and therefore link costs need to be minimized in preference over switch costs. A distributed overlay tends to have lower link costs because there is usually a greater probability that total path distances can be minimized because of greater connectivity. More connections set up the potential for more traffic flow path choices allowing each traffic flow to be sent along shorter paths. In legacy network topology designs that have many nodes with high connectivity, the overlay link costs can be relatively similar between designs and the switch costs can have a large impact upon total cost

Conception et mise à jour des réseaux de télécommunication

Conception des réseaux de télécommunication -- Topological design of two-level telecommunication networks with modular switches -- Heuristics for the topological design problem of two-level multitechnology telecommunication networks with modular switches -- Mise à jour des réseaux de télécommunication -- Topological expansion of multiple ring metropolitan area networks -- Tabu search and post-optimization algorithms for the topological update of two-level networks with modular switches -- The initial heuristic -- The tabu algorithm -- The post-optimization algorithm -- Ring backbone topology