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We propose a mixed-integer programming (MIP) formulation for a problem of optimal dimensioning of equipment of the fiber-to-the-home optical access network (FTTH-OAN). The optimization aims at minimizing capital expenditures (CAPEX) related to deployment of the FTTH-OAN, i.e., the cost of active equipment (OLTs and OLT cards), cost of passive equipment (optical splitters, cables, fibers, fibers terminations, splices, closures), cost of site preparations (building, cabinets), and cost of necessary labor (duct preparation and rollout of cables). The formulation has been implemented and validated. General results based on selected real-world scale numerical experiments are presented. [ABSTRACT FROM AUTHOR]

Radio links in wireless mesh networks (WMN) can select one of several modulation and coding schemes (MCS). A MCS assignment influences links data rates and their mutual interference, and therefore should be optimized. We consider joint optimization of link rate assignment and transmission scheduling in order to maximize the minimal flow in a WMN. One of the main difficulties stems from the requirement that each link has to use only one selected MCS for all its transmissions. This requirement leads to a complicated exact branch-and-price method, which is quite time-consuming for networks of practical size. Thus, we propose an original heuristic based on simulated annealing that utilizes specific characteristics of the problem. The method provides a balance between sub-optimality of the obtained solutions and the running time. The presented method is the main purpose and novelty of the paper. An extensive numerical study illustrates the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

The paper is devoted to modeling and optimization of reliable wireless mesh networks that employ directional antennas. We introduce two mixed-integer programming formulations that allow to simultaneously characterize routing patterns and transmission schedules. The first model allows for maximizing the minimal flow in a network. The second model involves reliability constraints and aims at minimizing the number of used directional antennas. In both cases locations of mesh routers are known. However, the number of installed radio interfaces and their directions are subject to optimization. We discuss a way of solving a cost minimization problem based on the introduced characterization, and present an extensive numerical study that illustrates the efficiency of the solution algorithm. We also provide an algorithm capable of verifying feasibility of obtained solutions. Moreover, in rare cases of failed verification, the algorithm provides additional constraints that should be added to the problem. [ABSTRACT FROM AUTHOR]

Finding optimal routes and spectrum allocation in flexgrid optical networks, known as the RSA problem, is an important design problem in transport communication networks. The problem is $$\mathcal{NP }$$ NP -hard, and its intractability becomes profound when network instances with several tens of nodes and several hundreds of demands are to be solved to optimum. In order to deal with such instances, large-scale optimization methods need to be considered. In this work, we present a column (more precisely, path) generation-based method for the RSA problem. The method is capable of finding reasonable sets of lightpaths, avoiding large sets of precomputed paths, and leading to high-quality solutions. Numerical results illustrating effectiveness of the proposed method for obtaining solutions for large RSA problem instances are presented. [ABSTRACT FROM AUTHOR]

Primary and backup paths in MPLS fast reroute (FRR) may be established as shortest paths according to the administrative link costs of the IP control plane, or as explicitly calculated arbitrary paths. In both cases, the path layout can be optimized so that the maximum link utilization for a specific traffic matrix and for a set of considered failure scenarios is minimized. In this paper, we propose a linear program for the optimization of the path layout for explicitly calculated paths, which can either produce single paths and route entire traffic along those paths, or generate multiple paths and spread the traffic among those paths providing load balancing. We compare the resulting lowest maximum link utilization in both cases with the lowest maximum link utilization that can be obtained by optimizing unique IP-based paths. Our results quantify the gain in resource efficiency usage provided by optimized explicit multiple paths or explicit single paths as compared to optimized IP-based paths. Furthermore, we investigate if explicit path layouts cause an increased configuration effort compared to IP-based layouts and if yes, to what extend. [ABSTRACT FROM AUTHOR]

Given 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 of the original problem (obtaining, in this way, a lower bound and a set of paths for each commodity) and, in the second step, we apply a multi-start local search with path relinking heuristic on the solution space defined by the paths of the first step. Here, we propose a hybridization approach of the metaheuristic with column generation that can be seen as an enhanced version of the previous approach: we run column generation not only at the beginning (to define the initial search space) but also during the search. These additional column generation steps consist in solving a perturbed problem defined by the incumbent solution. In the previous paper, we have shown that the first approach is efficient in obtaining near optimal routing solutions within short running times. With the enhanced version, we show through computational results that the additional paths, introduced by the additional column generation steps, either improve the efficiency of the algorithm or show similar efficiency in the cases where the original algorithm is already very efficient. [ABSTRACT FROM AUTHOR]

Network re-optimization is a process that must be triggered periodically in order to improve the inefficient resource allocation of online routing heuristics due to the uncertainty of online lightpath demand arrivals and departures. Network re-optimization involves two tasks: a) finding new lightpaths for a (sub)set of current demands, i.e. rerouting, and b) migrating the current traffic to the new configuration diminishing traffic disruptions, i.e. lightpath reconfiguration. If not controlled, excessive traffic disruptions may be a cause of violations of clients' Service Level Agreement, which should be compensated by the network operator with penalization fees. So far, rerouting and reconfiguration tasks of a re-optimization process have been done separately, hence, efforts in trying to achieve the best network performance (rerouting) yields to solutions incurring on unacceptable traffic disruptions (reconfiguration) and vice-versa. In this paper, given a time-disruption threshold for reconfiguring every demand, we present a novel methodology consisting on two procedures that collaboratively find the best network performance without incurring on penalization fees. Our numerical results are extremely encouraging: in our scenarios, it is always possible to achieve an optimal routing performance without incurring on penalization fees. [ABSTRACT FROM AUTHOR]

In 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 of demands to the trees, in order to achieve an optimal load balancing on the links of the network. In this paper we consider models and solving techniques for lexicographical optimization of two load balancing objective functions. The first objective is the min-max optimization of the n worst link loads (with n up to the total number of network links), and the second objective is the minimization of the average link load (when n is smaller than the total number of network links). Besides exact methods, a heuristic technique that can compute both feasible solutions and lower bounds for the addressed optimization problem is proposed. Finally, we discuss effectiveness of different solution using results of a numerical study of realistic case studies. [ABSTRACT FROM AUTHOR]

An introduction to articles published in this issue is presented including A non-cooperative game-theoretic framework for resource allocation in network virtualization, The IPv6 QoS system implementation in virtual infrastructure and Methods of network resource provisioning for the Future Internet IIP Initiative.

As today’s market forces the implementation of quality-of-service-enabled services spanned over multiple administrative domains, isolated and locally optimized interdomain routing decisions become increasingly inadequate. Instead, coordinated routing models are required together with joint optimization goals. Available papers and standardization documents focus on the description of technical means for deployment of interdomain transport services giving little (or no) attention to the problem of evaluating effective interdomain routing patterns. Our paper aims at closing this gap. It presents an iterative distributed process where domains cooperatively determine a (sub)optimal, with respect to a common utility function, flow of interdomain traffic. If all the cooperating domains adhere to the results of this process, they can reduce their operational costs, speed up operations, and increase profits. This paper is a continuation of Tomaszewski et al. (2007) and Pióro et al. (2007)—it introduces a modified problem formulation and analyzes the influence of aggregation of intradomain topology on speed and quality of the resolution process. [ABSTRACT FROM AUTHOR]

The 14th edition of International Telecommunications Network Strategy and Planning Symposium (shortly: Networks 2010) held in Warsaw, Poland. Networks 2010 was a four-day professional and scientific event organized by Warsaw University of Technology in co-operation with Polish Association of Telecommunication Engineers (SIT). The conference was focused on network design and planning methods including the issues of routing, traffic flows and optimization that are necessary to deliver the promise of the Network of the Future. Over 100 technical papers submitted by researchers form America, Asia, Australia, and Europe were carefully reviewed by the Members of the Technical Program Committee and external reviewers. The accepted 51 high quality papers were finally organized into 16 technical sessions. 6 keynote talks, 8 invited papers, and 4 tutorials enriched the conference program. Authors of the top 17 regular papers have been invited to publish extended versions of their papers in this special issue of Telecommunication Systems Journal. [ABSTRACT FROM AUTHOR]