Showing papers on "Network planning and design published in 1994"
TL;DR: In this paper, the authors present a structured review of research on the hub network design problem, and give brief empirical examples of eight different network design protocols, including Hub-and-Spoke (H&S) protocols.
317 citations
23 Jan 1994
TL;DR: This paper presents an approximation algorithm with a performance guarantee of 2TH(fmax) = 2(1 + $ + g +) where fmax is the maximum requirement, and improves upon the best previously known performance guarantees of 2fmax.
Abstract: 1 Introduction We consider a class of network design problems in which one needs to find a minimum-cost network satisfying cer-tam connectivity requirements. For example, in the snr-vivable network design problem, the requirements specify that there should be at least r(v, UJ) edge-disjoint paths between each pair of vertices v and w. We present an approximation algorithm with a performance guarantee of 2TH(fmax) = 2(1 + $ + g +. .. + &) where fmax is the maximum requirement. This improves upon the best previously known performance guarantee of 2fmax. We also show that our analysis is tight, up to a constant factor. In addition , we present approximation algorithms for two natural variations of the problem involving capacities. Our algorithms are based on a primal-dual approximation method for approximating a class of integer linear programs. Network design problems have a wide range of practical applications, ranging from telecommunications to transportation problems [lo]. In this paper, we will investigate approximation algorithms for several basic network design problems. In a network design problem, the input consists of an undirected graph G = (V, E), where each edge e E E has a nonneg-ative cost c(e), and we wish to select a minimum-cost subgraph that satisfies certain specified connec-tivity requirements. A general way to specify these constraints is to require, for each S c V, that the subgraph must contain at least f(S) edges in the cut 6(S) = {(v, w) E E : v E S, w $! S}, where we assume that there is a polynomial-time subroutine to compute f. Young Investigator Grant CC%8858097 with matching funds from AT&T, DEC, and 3M, and a grant from Powell Foundation. There has been a great deal of recent attention on the design and analysis of approximation algorithms for network design problems. There are two primary variants of these problems: one in which a solution may include multiple copies of each edge, and one in which this is forbidden. We first focus on the latter case. Extending work of Klein & Ravi [9] for proper function with range {0,2}, Williamson, Goemans, Mihail, & Vazirani [14] gave a polynomial-time 2fmax-approximation algorithm when the function f is proper, where fmax = maxscv f(S) and a p-approximation algorithm is an algorithm that always delivers a solution of cost at most p times the optimum. We shall defer the definition of proper functions , but we note …
263 citations
TL;DR: In this paper, a branch and bound algorithm and a heuristic procedure partitioning the set of solutions on the basis of hub locations are presented to solve the capacitated hub-and-spoke network design problem.
221 citations
TL;DR: The proposed planning model is a two-stage stochastic linear program (SLP) with recourse, a sampling based algorithm called Stochastic decomposition (SD) for very large-scale SLPs, such as the ones solved in this application.
Abstract: We study a planning problem associated with networks for private line services. In these networks, demands are known to exhibit considerable variability, and as such, they should be treated as random variables. The proposed planning model is a two-stage stochastic linear program (SLP) with recourse. Due to the enormous size of the deterministic equivalent, we choose a sampling based algorithm calledstochastic decomposition (SD). For very large-scale SLPs, such as the ones solved in this application, SD provides an effective methodology. The model presented in this paper is validated by using a detailed simulation of the network. We report results with a network that has 86 demand pairs, 89 links and 706 potential routes.
196 citations
TL;DR: In this article, the authors present a method that incorporates system uncertainty in monitoring network design and provides network alternatives that are noninferior with respect to several objectives, such as minimizing the number of monitoring wells, maximizing the probability of detecting a contaminant leak, and minimizing the expected area of contamination at the time of detection.
Abstract: The design of a monitoring network to provide initial detection of groundwater contamination at a waste disposal facility is complicated by uncertainty in both the characterization of the subsurface and the nature of the contaminant source. In addition, monitoring network design requires the resolution of multiple conflicting objectives. A method is presented that incorporates system uncertainty in monitoring network design and provides network alternatives that are noninferior with respect to several objectives. Monte Carlo simulation of groundwater contaminant transport is the method of uncertainty analysis. The random inputs to the simulation are the hydraulic conductivity field and the contaminant source location. The design objectives considered are (1) minimize the number of monitoring wells, (2) maximize the probability of detecting a contaminant leak, and (3) minimize the expected area of contamination at the time of detection. The network design problem is formulated as a multiobjective, integer programming problem and is solved using simulated annealing. An application of the method illustrates the configurations of noninferior network solutions and the trade-offs between objectives. The probability of detection can be increased either by using more monitoring wells or by locating the wells farther from the source. The latter case results in an increase in the average area of the detected contaminant plumes at the time of initial detection. If monitoring is carried out very close to the contaminant source to reduce the expected area of a detected plume, a large number of wells are required to provide a high probability of detection. A sensitivity analysis showed that the predicted performance of a given number of wells decreases significantly as the heterogeneity of the porous medium increases. In addition, a poor estimate of hydraulic conductivity was shown to result in optimistic estimates of network performance. In general, the trade-offs between monitoring objectives are an important factor in network design unless the cost (as expressed by the number of monitoring wells) is of limited concern.
168 citations
TL;DR: Analysis of actual holding time distributions in conversations, facsimile and voice mail connections revealed that these distributions radically differ from the exponential distribution, which can have a significant impact on the traffic stream presented to the CCS network.
Abstract: The message traffic offered to the CCS signaling network depends on and is modulated by the traffic characteristics of the circuit switched calls supported by the CCS network. Most previous analyses of CCS network engineering, performance evaluation and congestion control protocols generally assume an exponential holding time of circuit switched calls. Analysis of actual holding time distributions in conversations, facsimile and voice mail connections revealed that these distributions radically differ from the exponential distribution. Especially significant is the large proportion of very short calls in real traffic in comparison with the exponential distribution model. The diversity of calls (partial dialing, subscriber busy, no answer) and services results in a multi-component call mix, with even larger proportion of short time intervals between message-generating events. Very short call holding times can have a significant impact on the traffic stream presented to the CCS network: for calls with short holding times, the different CCS messages arrive relatively close to each other, and this manifests as burstiness in the CCS traffic stream. >
159 citations
TL;DR: A model and a set of solution techniques for an important problem arising in the design of survivable telecommunication networks utilizing fiber-optics-based technologies and are being successfully applied to actual network design problems arising in Bell operating companies and other telecommunication providers.
Abstract: We provide a model and a set of solution techniques for an important problem arising in the design of survivable telecommunication networks utilizing fiber-optics-based technologies. The emergence of a synchronous standard for optical signaling called "SONET" allows for an economic implementation of ring designs that provides protection for high capacity services. An objective is to choose a loading of the demands onto a ring design that minimizes associated equipment and facility costs while providing capacity for alternative routing should some link or node fail. After the computational complexity of the problem has been determined, three approximation heuristics, including a mathematical programming dual-ascent solution technique, are described and compared. The heuristics are being successfully applied to actual network design problems arising in Bell operating companies and other telecommunication providers.
156 citations
TL;DR: It is shown that a stochastic user equilibrium based on the logit model leads to a differentiable and large-scale, but tractable, version of the NDP.
Abstract: The continuous Network Design Problem (NDP) deals with determining optimal expansions for the capacities of a street network, subject to the constraint that the street traffic volumes must be the outcome of a user-optimal equilibrium assignment. Although the use of deterministic equilibrium methods tends to produce computationally intractable problems, in this paper it is shown that a stochastic user equilibrium based on the logit model leads to a differentiable and large-scale, but tractable, version of the NDP. A procedure for computing the derivatives of the stochastic user equilibrium (SUE) assignment without having to first compute the route choice probabilities is given, and this procedure is coupled with two standard algorithms for solving nonlinear programs, the generalized reduced gradient method and sequential quadratic programming. These algorithms are tested on several example networks, and the results of these tests suggest that the SUE-constrained version of the NDP offers both a promising heuristic for solving DUE-constrained problems as well as a viable procedure in its own right.
148 citations
TL;DR: In this paper, the authors studied the problem of extending the capacity of a network by discrete steps as cheaply as possible, such that the given traffic demand can be accommodated even when a single edge or node in the network fails.
Abstract: The design of cost-efficient networks satisfying certain survivability constraints is of major concern to the telecommunications industry. In this paper we study a problem of extending the capacity of a network by discrete steps as cheaply as possible, such that the given traffic demand can be accommodated even when a single edge or node in the network fails. We derive valid and nonredundant inequalities for the polyhedron of capacity design variables, by exploiting its relationship to connectivity network design and knapsack-like subproblems. A cutting plane algorithm and heuristics for the problem are described, and preliminary computational results are reported.
131 citations
TL;DR: The approach addresses the network survivability objective by considering two grade-of-service parameters: one for the traffic network under normal operating condition and the other for affected part of the network under a network failure.
Abstract: Addresses the problem of network survivability by presenting a unified approach where the wide-area circuit-switched teletraffic network and the underlying transmission facility network are considered simultaneously. The author assumes the backbone circuit-switched teletraffic network to be nonhierarchical with dynamic call routing capabilities. The transmission facility network is considered to be sparse (as is observed for emerging fiber optic networks) and is assumed to be two-arc connected. The approach addresses the network survivability objective by considering two grade-of-service parameters: one for the traffic network under normal operating condition and the other for affected part of the network under a network failure. The author presents unified mathematical models and develops heuristic algorithms. The author then presents computational results to demonstrate the effectiveness of the unified approach. >
108 citations
TL;DR: Based on the survivability framework, models for network survivability assessment and analysis are considered, and performance measures are described, and examples illustrate the application of this framework in network design and planning.
Abstract: The article is based on the results of ANSI Technical Subcommittee T1A1 activities in the area of a general framework for telecommunication network survivability performance. The issues of users' expectations and requirements, outage categorization, and a framework for analysis of survivability techniques are discussed. Based on the survivability framework, models for network survivability assessment and analysis are considered, and performance measures are described. Examples illustrate the application of this framework in network design and planning. >
TL;DR: This paper studies a multi-facility network synthesis problem that arises in the topological design of hierarchical communication, transportation, and electric power distribution networks, and studies the relationship between alternative model formulations for this problem.
Abstract: This paper studies a multi-facility network synthesis problem, called the Two-level Network Design (TLND) problem, that arises in the topological design of hierarchical communication, transportation, and electric power distribution networks. We are given an undirected network containing two types of nodes—primary and secondary—and fixed costs for installing either a primary or a secondary facility on each edge. Primary nodes require higher grade interconnections than secondary nodes, using the more expensive primary facilities. The TLND problem seeks a minimum cost connected design that spans all the nodes, and connects primary nodes via edges containing primary facilities; the design can use either primary or secondary edges to connect the secondary nodes. The TLND problem generalizes the well-known Steiner network problem and the hierarchical network design problem. In this paper, we study the relationship between alternative model formulations for this problem (e.g., directed and undirected models), an...
TL;DR: It is shown that, with careful network design, the back-propagation learning procedure is an effective way of training neural networks for electrical load prediction.
TL;DR: This work presents local-improvement heuristics for a Service Network Design Problem encountered in the motor carrier industry, based upon subgradients derived from the optimal dual variables of the shipment routing subproblem.
Abstract: We present local-improvement heuristics for a Service Network Design Problem encountered in the motor carrier industry. The scheduled set of vehicle departures determines the right hand side of the capacity constraints of the shipment routing subproblem which is modeled as a multicommodity network flow problem. The heuristics, one for dropping a scheduled service and another for introducing a new service, are based upon subgradients derived from the optimal dual variables of the shipment routing subproblem. The basis of the multicommodity network flow problem is partitioned to facilitate the calculation of the dual variables, reduced costs and subgradients. These are determined in large part by additive and network operations, and only in small part by matrix multiplication. The results of our computational experimentation are presented.
Patent•
05 Oct 1994
TL;DR: In this article, the authors present a development environment which enables a user to define a separate finite state machine (FSM) for each port provided by a programmable telecommunications switch.
Abstract: A telecommunications protocol development environment which enables a user to define a separate finite state machine for each port provided by a programmable telecommunications switch. Protocols for various telecommunications applications and software layers may be developed.
TL;DR: A dual-based algorithm for the Multi-level Network Design MLND problem, which generalizes the well-known Steiner network problem and the hierarchical network design problem, and has applications in telecommunication, transportation, and electric power distribution network design.
Abstract: Given an undirected network with L possible facility types for each edge, and a partition of the nodes into L levels or grades, the Multi-level Network Design MLND problem seeks a fixed cost minimizing design that spans all the nodes and connects the nodes at each level by facilities of the corresponding or higher grade. This problem generalizes the well-known Steiner network problem and the hierarchical network design problem, and has applications in telecommunication, transportation, and electric power distribution network design. In a companion paper we studied alternative model formulations for a two-level version of this problem, and analyzed the worst-case performance of several heuristics based on Steiner network and spanning tree solutions. This paper develops a dual-based algorithm for the MLND problem. The method first performs problem preprocessing to fix certain design variables, and then applies a dual ascent procedure to generate upper and lower bounds on the optimal value. We report extensive computational results on large, random two-level test problems containing up to 500 nodes, and 5,000 edges with varying cost structures. The integer programming formulation of the largest of these problems has 20,000 integer variables and over 5 million constraints. Our tests indicate that the dual-based algorithm is very effective, producing solutions that are within 0.9% of optimality.
Patent•
AT&T1
TL;DR: In this article, the dual operations of traffic data analysis and network surveillance in a telecommunications network are integrated to allow maintenance personnel to readily assess the impact of network element problems on the level of service.
Abstract: The dual operations of traffic data analysis and network surveillance in a telecommunications network are integrated to allow maintenance personnel to readily assess the impact of network element problems on the level of service More specifically, the present invention utilizes traffic data measurements to monitor the level of service provided by various network components By utilizing real-time or near real-time traffic data in this manner, switch maintenance activities may be prioritized so that, for example, equipment malfunctions having the greatest impact on the level of service may receive attention before those having little or no impact on service
01 Oct 1994
TL;DR: An approximation algorithm is proposed for this problem, which guaranteed a solution whose cost is greater than the optimum by a factor of at most log n (and constant in the planar case).
Abstract: This paper considers the problem of designing a minimum cost network meeting a given set of traffic requirements between n sites, using one type of channels of a given capacity, with varying set-up costs for different vertex pairs (comprised of a fixed part plus a part dependent on the pair). An approximation algorithm is proposed for this problem, which guaranteed a solution whose cost is greater than the optimum by a factor of at most log n (and constant in the planar case). The algorithm is based on an application of the recent construction of light-weight distance-preserving spanners.
TL;DR: A mathematical model of the problem is presented, and a heuristic solution based on the tabu search framework is developed to find optimal or near-optimal solutions to the problem of finding optimal clusters of offices.
Abstract: Optical fiber systems play an essential role in today's telecommunications networks. The recently standardized SONET Synchronous Optical Network technology has made rings the preferred architecture for designing survivable networks. The network design problem is very complex in nature, because it involves not only the configuration of rings at the logical level, but also the mapping of this configuration into physical fiber paths. This paper deals with the problem of finding optimal clusters of offices, which can be used as the basis for designing logical rings. A mathematical model of the problem is presented, and a heuristic solution based on the tabu search framework is developed to find optimal or near-optimal solutions.
TL;DR: The authors propose a passive protected DCS self-healing network (PPDSHN) architecture using a passive protection cross-connect network for network protection that may apply to not only the centralized and distributed control DCS network architectures, but also asynchronous, SONET and ATM DCS networks.
Abstract: The self-healing mesh network architecture using digital cross-connect systems (DCSs) is a crucial part of an integrated network restoration system. The conventional DCS self-healing networks using logical channel protection may require a large amount of spare capacity for network components (such as DCSs) and may not restore services fast enough (e.g., within 2 s). The authors propose a passive protected DCS self-healing network (PPDSHN) architecture using a passive protection cross-connect network for network protection. For the PPDSHN architecture, network restoration is performed in the optical domain and is controlled by electronic working DCS systems. Some case studies have suggested that the proposed PPDSHN architecture may restore services within a two-second objective with less equipment cost than the conventional DCS self-healing network architecture in high-demand metropolitan areas for local exchange carrier networks. The proposed PPDSHN architecture may apply to not only the centralized and distributed control DCS network architectures, but also asynchronous, SONET and ATM DCS networks. Transparency of line rates and transmission formats makes the PPDSHN network even more attractive when network evolution is a key concern of network planning. >
TL;DR: Experimental studies of several well‐known shortest‐paths algorithms adapted to the task of finding the k‐successively‐shortest link‐disjoint replacement paths for restoration in a telecommunications network with n nodes demonstrate a speed‐up of nearly an order of magnitude over the simpler O(kn2) implementation in the largest networks tested.
Abstract: The problem of finding shortest paths arises in many contexts; testing restoration algorithms and developing design packages for large telecommunications networks are two cases where the simple task of finding sets of restoration paths can consume up to 95 per cent of the execution time of an application program. This paper presents experimental studies of several well-known shortest-paths algorithms adapted to the task of finding the k-successively-shortest link-disjoint replacement paths for restoration in a telecommunications network with n nodes. The implementations range in complexity from O(kn2) when based on Dijkstra's original method, through several improvements to an efficient implementation of O(kn[v+longn]) complexity, and finally to an O(kn) implementation for the special case of edge-sparse graphs with small integer edge weights. Here v is the maximum degree of a node in the network. Several alternatives were tested during the course of these studies, particularly with a view to minimizing the number of heap updates, These alternatives are possible because we are searching for several paths between a given pair of nodes, rather than just one path between one or more pairs of nodes. Two fairly straightforward changes yield a decrease in execution time, whereas a more complex heap management strategy consumes as much time in the added code as it releases from the main routine. Experimental results confirm the theoretical complexity of q k n log n) and demonstrate a speed-up of nearly an order of magnitude over the simpler O(kn2) implementation in the largest networks tested. The optimized implementation is recommended for planning and operational applications of k-shortest paths rerouting for telecommunications network restoration and restorable network design. If hop counts or small integer link weights can be used to measure distances, then the qkn) implementation is recommended, as typical telecommunications networks are edge-sparse.
TL;DR: A model to design an airline network and determine flight frequencies is developed based on the fuzzy set theory, which uses fuzzy logic to determine the route candidates to make the flights, and the second part of the model is based on fuzzy linear programming to determineFlight frequencies on the routes candidates.
Abstract: This paper develops a model to design an airline network and determine flight frequencies. The basic input data are the estimated numbers of passengers between pairs of cities. It is often impossible to estimate these numbers with enough precision (i.e. there is a degree of uncertainty surrounding the numbers of passengers between pairs of cities). Uncertainty is also frequent in the estimation of future airline carrier costs. The fuzzy set theory is an extremely convenient mathematical device with which to solve problems containing uncertainty, sujectivity, ambiguity and indetermination. Without aspiring to revolutionize airline netqork design, the basic goal of this paper is to present the fuzzy set tools and their potential application to a generic airline network design problem. The model developed is based on the fuzzy set theory. The first part of the model uses fuzzy logic to determine the route candidates to make the flights, and the second part of the model is based on fuzzy linear programming to determine flight frequencies on the route candidates. The model is supported by numerical examples.
TL;DR: The success of UMTS relies not only on the development of a flexible air interface, efficient coding techniques, and handset technology; it is equally important to design a system that can support the underlying technology and to interface with other networks.
Abstract: The success of UMTS relies not only on the development of a flexible air interface, efficient coding techniques, and handset technology; it is equally important to design a system that can support the underlying technology and to interface with other networks. >
TL;DR: The fuzzy logic provides a method of systematically changing the network configuration while simultaneously considering all of the evaluation criteria to adapt the current network configuration to one which is close to (if not at) the optimal configuration.
Abstract: After a problem has been formulated for solution by using artificial neural network technology, the next step is to determine the appropriate network configuration to be used in achieving a desired level of performance. Due to the real world environment and implementation constraints, different problems require different evaluation criteria such as: accuracy, training time, sensitivity, and the number of neurons used. Tradeoffs exist between these measures, and compromises are needed in order to achieve an acceptable network design. This paper presents a method using fuzzy logic techniques to adapt the current network configuration to one which is close to (if not at) the optimal configuration. The fuzzy logic provides a method of systematically changing the network configuration while simultaneously considering all of the evaluation criteria. The optimal configuration is determined by a cost function based on the evaluation criteria. The proposed methodology is applied to an elementary classifier network as an illustration. The procedure is then used to automatically configure a network used to detect incipient faults in an induction motor as a real world application. >
12 Jun 1994
TL;DR: The authors formulate the problem of network design of personal communication services (PCS) exactly as an integer programming problem and propose three heuristic solutions and show that two of them perform extremely well.
Abstract: Considers a problem of network design of personal communication services (PCS). The problem is to assign cells to the switches of a PCS network in an optimum manner. The authors consider two types of costs. One is the cost of handoffs between cells. The other is the cost of cabling (or trunking) between a cell site and its associated switch. The problem is constrained by the call volume that each switch can handle. They formulate the problem exactly as an integer programming problem. They also propose three heuristic solutions for this problem and show that two of them perform extremely well. >
TL;DR: In this paper, a simple conceptual framework for planning store networks is presented, which can be used as a starting point for a variety of retail businesses and highlights the integral link between the location of a particular format of retail outlet and the benefit which they offer to the customer segments which they serve.
Abstract: Highlights the integral link between the location of a particular format of retail outlet and the benefit which they offer to the customer segments which they serve. Outlines a simple conceptual framework for planning store networks which can be used as a starting point for a variety of retail businesses. This depends on the degree of portability of the product and the emphasis placed by the customer on the relative importance of convenience and comparison in the buying process. Four principle types of retail location positions are identified by the framework and the main locational factors or “drivers” of the success of each are explained. Underlines the importance of retailers recognizing the ongoing nature of the network planning process, involving store rationalization, relocation and refurbishment, as well as the roll out of new store concepts. It is anticipated that the framework should prove useful both to retailers setting out on a formal process of network planning as well as to planning authorit...
Journal Article•
TL;DR: The uncapacitated facility location model is applied and a topological optimization of its subnetwork based on a simple heuristic is analyzed for each concentrator to solve the upper level subnetwork connecting the concentrators to a root node.
TL;DR: The approach is aimed at accurately reproducing dynamic network behavior at a level similar to the models described by Hutchinson and Patten (1986), and Unger and Bidulock (1982) .
Abstract: Simulating trunk and signaling networks allows planners to examine network survivability, capacity, and the impact of new service introductions. The challenge is to accurately predict network performance and behavior for a rapidly changing environment, and for the very large networks that are encountered in the public telephone system. This paper describes the discrete event modeling of SS7 signaling networks that enable dynamic network analysis for very large, highly realistic, network models. The primary distinction between the authors approach and related work is the development of a very detailed model, one that incorporates most SS7 message-handling and network-management procedures. Their approach is aimed at accurately reproducing dynamic network behavior at a level similar to the models described by Hutchinson and Patten (1986), and Unger and Bidulock (1982) . They define network simulation objectives and the SS7 model components and functions, and then give a brief overview of how a specific network model is created, including a description of the model's implementation and how it was validated. They also discuss a model and simulation experiments for a large part of the Ameritech network. >