scispace - formally typeset
Search or ask a question

Showing papers on "Network planning and design published in 1995"


Journal ArticleDOI
TL;DR: It is shown that the long-range dependence property allows us to clearly distinguish between measured data and traffic generated by VBR source models currently used in the literature, and gives rise to novel and challenging problems in traffic engineering for high-speed networks.
Abstract: We analyze 20 large sets of actual variable-bit-rate (VBR) video data, generated by a variety of different codecs and representing a wide range of different scenes. Performing extensive statistical and graphical tests, our main conclusion is that long-range dependence is an inherent feature of VBR video traffic, i.e., a feature that is independent of scene (e.g., video phone, video conference, motion picture video) and codec. In particular, we show that the long-range dependence property allows us to clearly distinguish between our measured data and traffic generated by VBR source models currently used in the literature. These findings give rise to novel and challenging problems in traffic engineering for high-speed networks and open up new areas of research in queueing and performance analysis involving long-range dependent traffic models. A small number of analytic queueing results already exist, and we discuss their implications for network design and network control strategies in the presence of long-range dependent traffic. >

1,216 citations


Journal ArticleDOI
TL;DR: The results show that strong cutting planes can be an effective modeling and algorithmic tool for solving problems of the size that arise in the telecommunications industry.
Abstract: This paper studies a topical and economically significant capacitated network design problem that arises in the telecommunications industry. In this problem, given point-to-point communication demand in a network must be met by installing loading capacitated facilities on the arcs: Loading a facility incurs an arc specific and facility dependent cost. This paper develops modeling and solution approaches for loading facilities to satisfy the given demand at minimum cost. We consider two approaches for solving the underlying mixed integer program: a Lagrangian relaxation strategy, and a cutting plane approach that uses three classes of valid inequalities that we identify for the problem. We show that a linear programming formulation that includes these inequalities always approximates the value of the mixed integer program at least as well as the Lagrangian relaxation bound. Our computational results on a set of prototypical telecommunication data show that including these inequalities considerably improves the gap between the integer programming formulation and its linear programming relaxation: from an average of 25% to an average of 8%. These results show that strong cutting planes can be an effective modeling and algorithmic tool for solving problems of the size that arise in the telecommunications industry.

242 citations


Journal ArticleDOI
TL;DR: The overall dynamic bandwidth-allocation scheme presented is shown to be promising and practically feasible in obtaining efficient transmission of real-time video traffic.
Abstract: This paper presents a novel approach to dynamic transmission bandwidth allocation for transport of real-time variable-bit-rate video in ATM networks. Video traffic statistics are measured in the frequency domain. The low-frequency signal captures the slow time-variation of consecutive scene changes while the high-frequency signal exhibits the feature of strong frame autocorrelation. Our queueing study indicates that the video transmission bandwidth in a finite-buffer system is essentially characterized by the low-frequency signal. We further observe in typical JPEG/MPEG video sequences that the time scale of video scene changes is in the range of a second or longer, which localizes the low-frequency video signal in a well-defined low-frequency band. Hence, in a network design it is feasible to implement dynamic allocation of video transmission bandwidth using on-line observation and prediction of scene changes. Two prediction schemes are examined: recursive least square method and time delay neural network method. A time delay neural network with low-complexity high-order architecture, called "pi-sigma network," is successfully used to predict scene changes. The overall dynamic bandwidth-allocation scheme presented is shown to be promising and practically feasible in obtaining efficient transmission of real-time video traffic. >

178 citations


Journal ArticleDOI
TL;DR: In this paper, the authors examined whether there is a substantial additional payoff to be derived from using mathematical optimization techniques to globally define a set of mini-clusters and presented a new approximate method to mini clustering that involves solving a multi-vehicle pick-up and delivery problem with time windows by column generation.
Abstract: This paper examines whether there is a substantial additional payoff to be derived from using mathematical optimization techniques to globally define a set of mini-clusters. Specifically, we present a new approximate method to mini-clustering that involves solving a multi-vehicle pick-up and delivery problem with time windows by column generation. To solve this problem we have enhanced an existing optimal algorithm in several ways. First, we present an original network design based on lists of neighboring transportation requests. Second, we have developed a specialized initialization procedure which reduces the processing time by nearly 40%. Third, the algorithm was easily generalized to multi-dimensional capacity. Finally, we have also developed a heuristic to reduce the size of the network, while incurring only small losses in solution quality. This allows the application of our approach to much larger problems. To be able to compare the results of optimization-based and local heuristic mini-clustering,...

173 citations


Journal ArticleDOI
TL;DR: The authors formulate the problem exactly as an integer programming problem and propose a heuristic solution for this problem and show that it performs 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. The authors formulate the problem exactly as an integer programming problem. They also propose a heuristic solution for this problem and show that it performs extremely well. >

162 citations


Journal ArticleDOI
TL;DR: The first polynomial-time approximation algorithm for finding a minimum-cost subgraph having at least a specified number of edges in each cut is presented, which shows the importance of this technique in designing approximation algorithms.
Abstract: We present the first polynomial-time approximation algorithm for finding a minimum-cost subgraph having at least a specified number of edges in each cut. This class of problems includes, among others, the generalized Steiner network problem, also called the survivable network design problem. Ifk is the maximum cut requirement of the problem, our solution comes within a factor of 2k of optimal. Our algorithm is primal-dual and shows the importance of this technique in designing approximation algorithms.

151 citations


01 Jan 1995
TL;DR: A cutting plane algorithm is presented for solving the following telecommunications network design problem: given point-to-point traffic demands in a network, specified survivability requirements and a discrete cost/capacity function for each link, find minimum cost capacity expansions satisfying the given demands.
Abstract: We present a cutting plane algorithm for solving the following telecommunications network design problem: given point-to-point traffic demands in a network, specified survivability requirements and a discrete cost/capacity function for each link, find minimum cost capacity expansions satisfying the given demands. This algorithm is based on the polyhedral study described in [19]. In this article we describe the underlying problem, the model and the main ingredients in our algorithm. This includes: initial formulation, feasibility test, separation for strong cutting planes, and primal heuristics. Computational results for a set of real-world problems are reported.

142 citations


Journal ArticleDOI
TL;DR: In this paper, a sampling network design model is presented that evaluates the trade-off between the varying costs of different types of data and the contribution of those data to improving model reliability.
Abstract: A sampling network design model is presented that evaluates the trade-off between the varying costs of different types of data and the contribution of those data to improving model reliability The methodology couples parameter-estimate and model-prediction uncertainty analyses with optimization to identify the mix of hydrogeologic information (eg, head, concentration, and/or hydraulic conductivity measurement locations) that will minimize model prediction uncertainty for a given data collection budget Two alternative optimization algorithms are presented and compared: a branch-and-bound algorithm and a genetic algorithm A series of synthetic examples are presented to demonstrate the adaptability of the methodology to different sampling scenarios The examples reveal two important properties of this network design problem First, model-parameter and model-prediction uncertainty analyses are important components of the network design methodology because they provide a natural framework for evaluating the cost/information trade-off for different types of data and different sampling network designs Second, the genetic algorithm can identify near-optimal solutions for a small fraction of the computational effort needed to determine the globally optimal solutions of the branch-and-bound algorithm

99 citations


Book ChapterDOI
01 Jan 1995
TL;DR: In this article, the authors describe a range of issues related to the design and analysis of networks which are subject to the random failure of their components, including data communications networks, voice communication networks, transportation networks, computer architectures, electrical power networks and command and control systems.
Abstract: Publisher Summary Network reliability encompasses a range of issues related to the design and analysis of networks which are subject to the random failure of their components. Relatively simple, and yet quite general, network models can represent a variety of applied problem environments. Network classes for which the models are discussed are particularly appropriate include data communications networks, voice communications networks, transportation networks, computer architectures, electrical power networks and command and control systems. The ultimate objective of research in the area of network reliability is to give design engineers procedures to enhance their ability to design networks for which reliability is an important consideration. Ideally, one would like to generate network design models and algorithms which take as input the characteristics of network components as well as network design criteria, and produce as output an "optimal" network design.

94 citations


Book ChapterDOI
01 Jan 1995
TL;DR: A very general model (for undirected networks) is presented which includes practical, as well as theoretical, problems, including the well-studied minimum spanning tree, Steiner tree, and minimum cost k-connected network design problems.
Abstract: Publisher Summary This chapter focuses on the important practical and theoretical problem of designing survivable communication networks, i.e., communication networks that are still functional after the failure of certain network components. A very general model (for undirected networks) is presented which includes practical, as well as theoretical, problems, including the well-studied minimum spanning tree, Steiner tree, and minimum cost k-connected network design problems. The development of this area starts with outlining structural properties which are useful for the design and analysis of algorithms for designing survivable networks. These lead to worst-case upper and lower bounds. Heuristics that work well in practice are also described. Polynomially-solvable special cases of the general survivable network design problem are summarized. The chapter discusses polyhedral results from the study of these problems as integer programming models. The chapter provides complete and nonredundant descriptions of a number of polytopes related to network survivability problems of small dimensions. The computational results using cutting plane approaches basedon the polyhedral results are given. The results show that these methods are efficient and effective in producing optimal or near-optimal solutions to real-world problems. A brief review of the work on survivability models of directed networks is given.

88 citations


Proceedings ArticleDOI
01 Sep 1995
TL;DR: An O(log m) approximation bound algorithm is provided for RBSP, where m < n is the minimum number of sides.

Patent
29 Dec 1995
TL;DR: In this article, a system and method for using service impact analysis (SIA) to provide a telecommunications network carrier with improved real-time information on network failures is presented, which assesses the fault data to determine the actual service impact at a particular instant in time and the likely cause of the fault.
Abstract: A system and method for using service impact analysis (SIA) to provide a telecommunications network carrier with improved real-time information on network failures. The system monitors a network for faults by collecting fault data. The system assess the fault data to determine the actual service impact at a particular instant in time and the likely cause of the fault. The system also predicts future service impact based on collected historical data of the telecommunications network. The system thus associates equipment failures with actual and potential call traffic impact to provide both customer and network support operations with additional perspective on the service impact of a network equipment failure. This customer oriented view, rather that the traditional network oriented view, is significant in providing imported telecommunications service availability with limited human resources.

Journal ArticleDOI
TL;DR: A generalized solution approach based on Genetic Algorithm for Network Topology Design that is applicable to a wide range of other network design problems such as network expansion and file allocation is proposed.

Journal ArticleDOI
TL;DR: Some polyhedral results for network design problems with higher connectivity requirements are described and some preliminary computational results for a cutting plane algorithm are reported for various real-world and random problems with high connectivity requirements, which shows promise for providing good solutions to these difficult problems.
Abstract: We consider the important practical and theoretical problem of designing a low-cost communications network which can survive failures of certain network components. Our initial interest in this area was motivated by the need to design certain “two-connected” survivable topologies for fiber optic communication networks of interest to the regional telephone companies. In this paper, we describe some polyhedral results for network design problems with higher connectivity requirements. We also report on some preliminary computational results for a cutting plane algorithm for various real-world and random problems with high connectivity requirements, which shows promise for providing good solutions to these difficult problems.

Journal ArticleDOI
TL;DR: A multi-hour, multi-traffic class network (capacity) design model for providing specified quality-of-service in such dynamically reconfigurable ATM networks based on the observation that statistical multiplexing of virtual circuits for a traffic class in a virtual path leads to decoupling of the network dimensioning problem into the bandwidth estimation problem and the combined virtual path routing and capacity design problem.
Abstract: The virtual path (VP) concept has been gaining attention in terms of effective deployment of asynchronous transfer mode (ATM) networks in recent years. In a recent paper, we outlined a framework and models for network design and management of dynamically reconfigurable ATM networks based on the virtual path concept from a network planning and management perspective. Our approach has been based on statistical multiplexing of traffic within a traffic class by using a virtual path for the class and deterministic multiplexing of different virtual paths, and on providing dynamic bandwidth and reconfigurability through virtual path concept depending on traffic load during the course of the day. In this paper, we discuss in detail, a multi-hour, multi-traffic class network (capacity) design model for providing specified quality-of-service in such dynamically reconfigurable networks. This is done based on the observation that statistical multiplexing of virtual circuits for a traffic class in a virtual path, and the deterministic multiplexing of different virtual paths leads to decoupling of the network dimensioning problem into the bandwidth estimation problem and the combined virtual path routing and capacity design problem. We discuss how bandwidth estimation can be done, then how the design problem can be solved by a decomposition algorithm by looking at the dual problem and using subgradient optimization. We provide computational results for realistic network traffic data to show the effectiveness of our approach. We show for the test problems considered, our approach does between 6% to 20% better than a local shortest-path heuristic. We also show that considering network dynamism through variation of traffic during the course of a day by doing dynamic bandwidth and virtual path reconfiguration can save between 10% and 14% in network design costs compared to a static network based on maximum busy hour traffic.

Journal ArticleDOI
TL;DR: The WaveARX network, a new neural network architecture, is introduced that integrates the multiresolution analysis concepts of the wavelet transform and the traditional AutoRegressive eXternal input model (ARX) into a three-layer feedforward network.
Abstract: The WaveARX network, a new neural network architecture, is introduced. Its development was motivated by the opportunity to capitalize on recent research results that allow some shortcomings of the traditional artificial neural net (ANN) to be addressed. ANN has been shown to be a valuable tool for system identification but suffers from slow convergence and long training time due to the globalized activation function. The structure of ANN is derived from trial and error procedures, and the trained network parameters often are strongly dependent on the random selection of the initial values. There are not even guidelines on the number of neurons needed. Also, few identification techniques are available for distinguishing linear from nonlinear contributions to a system's behavior. The WaveARX integrates the multiresolution analysis concepts of the wavelet transform and the traditional AutoRegressive eXternal input model (ARX) into a three-layer feedforward network. Additional network design problems are solved as the WaveARX formalisms provide a systematic design synthesis for the network architecture, training procedure, and excellent initial values of the network parameters. The new structure also isolates and quantifies the linear and nonlinear components of the training data sets. The wavelet function is extended to multidimensional input space using the concept of a norm. The capabilities of the network are demonstrated through several examples in comparison with some widely used linear and nonlinear identification techniques. Separately, the wavelet network of the WaveARX model is shown for the example investigated to have a better performance than two other existing wavelet-based neural networks.

Patent
10 Apr 1995
TL;DR: In this article, the authors proposed a tunable reception means tuned as a function of the density of the network traffic, thus being capable of being reconfigured as the function of requirements.
Abstract: In a telecommunications network organized in wavelength-division-multiplexed optical loops, each loop has tunable reception means tuned as a function of the density of the network traffic, thus being capable of being reconfigured as a function of requirements. The disclosed system can be applied to public, private and data communication networks.

Proceedings ArticleDOI
A.M. Shooman1
TL;DR: Various exact techniques whose complexity results in run-times short enough for practical network design are discussed.
Abstract: Communications networks used for transmitting and receiving voice or digital data involve copper wire, fiber optics, radio, satellite, and microwave links. In general, these networks are large, diffuse, and complex. Even using modern high-speed computers, exact computations of the network reliability for use as a figure of merit in an interactive network design procedure can take an inordinate amount of time. This paper discusses various exact techniques whose complexity results in run-times short enough for practical network design. We model the network by an undirected probabilistic graph whose vertices represent the nodes and whose edges represent the links. A special feature of our model is that it allows nodes to be imperfect and associates a reliability measure with each node, assumed to succeed or fail independently. Therefore, the network reliability measure is based upon the reliability measures of the individual links and nodes. >

Book ChapterDOI
01 Jan 1995
TL;DR: Taken as a whole, the models considered establish network optimization as an unusually powerful and rich modeling environment, adding evidence to justify the claim that applied mathematics, computer science, and operations research do indeed have much to offer to the world of practice.
Abstract: Publisher Summary This chapter discusses several applications of the following network optimization problems: shortest paths, maximum flows, minimum cost flows, assignment and matching's, minimum spanning trees, convex cost flows, generalized flows, multicommodity flows, the traveling salesman problem, and network design. The chapter describes the following forty two applications, drawn from the fields of operations research, computer science, the physical sciences, medicine, engineering, and applied mathematics. Some basic notation and definitions from graph theory as well as a mathematical programming formulation of the minimum cost flow problem, which is the core network flow problem that lies at the heart of network optimization is introduced. Some models are formulated naturally as network optimization problems; others don't appear naturally as network models, but are transformable into the form of network optimization problems (for example, by taking linear programming duals of "natural" formulations). Taken as a whole, the models considered establish network optimization as an unusually powerful and rich modeling environment, adding evidence to justify the claim that applied mathematics, computer science, and operations research do indeed have much to offer to the world of practice.

Book
01 Jan 1995
TL;DR: This paper presents the OSI Reference Model for Open Systems Interconnection, a reference model for open systems interconnection used in the development of telecommunications, and some of the standards used in that development.
Abstract: * Introduction * The Development of Telecommunications * Network Structures * Network Services. * Terminology * Regulation * Standards * The OSI Reference Model for Open Systems Interconnection * Conclusion * References

Journal ArticleDOI
Seok J. Koh1, Chae Y. Lee1
TL;DR: In this article, a tabu search procedure is developed to solve fiber optic communication network design problems with survivability constraints, and two systematic improving heuristics: delete-add and delete-link procedures are presented.

Patent
22 Jun 1995
TL;DR: In this article, an optimal amount of spare capacity for a network so that efficient distributed restoration of the network can take place in the event of a network failure is provided to a network modeling tool.
Abstract: To estimate an optimal amount of spare capacity for a network so that efficient distributed restoration of the network can take place in the event of a network failure, parameter assumptions and network design guidelines are provided to a network modeling tool to generate a desirable amount of spare links for the network. The spare links are allocated to the different nodes of the network. After a failure in the network, the result of the restoration of the network due to the failure is reported to the controller of the system. If necessary, the parameter assumptions and network design guidelines are updated and fed back to the network modeling tool for further refining the spare capacity of the network. An optimal amount of spare capacity is thus achieved by a continuous redeployment of the spare capacity output provided by the network modeling tool. Simulated failures and subsequent restorations of the network are provided to an exerciser periodically. Results from the exerciser further enhance the operations of the network modeling tool to provide an optimal amount of spare capacity for the telecommunications network.

Journal ArticleDOI
TL;DR: This paper examines the effects of dynamic user-equilibrium traffic assignment with scheduled trip arrival times on network design outcomes in comparison to outcomes with steady-state travel demands.
Abstract: This paper examines the effects of dynamic user-equilibrium (DUE) traffic assignment with scheduled trip arrival times on network design outcomes in comparison to outcomes with steady-state travel demands. The objective is to minimize systemwide travel cost by considering alternative link improvements to an existing network (e.g., select among budget-constrained subsets of link-improvement candidates). DUE is a temporal generalization of static user-equilibrium (SUE) assignment with additional constraints to insure temporally continuous trip paths and first-in first-out (FIFO) trip ordering between all origin-destination pairs. Previous research has not investigated the effects of dynamic travel demands and schedule delay (i.e., shifts by trips to earlier or later arrival times) on network design with multiple trip origins and destinations. DUE is formulated as a bilevel program of two subproblems solved successively by an iterative algorithm that consistently converges to solutions that closely satisfy t...

Journal ArticleDOI
G.R. Ash1
TL;DR: Dynamic traffic routing implements an integrated class-of-service routing feature for extending dynamic routing to emerging services, and provides a self-healing network capability to ensure a network-wide path selection and immediate adaptation to failure.
Abstract: Dynamic network evolution achieves network performance improvement and cost reduction by taking advantage of new advanced technologies being introduced into the network to achieve greater network flexibility and efficiency. The author describes the evolution of dynamic networks, with examples drawn from the AT&T DNHR network deployed in the '80s and RTNR network deployed in the '90s. Dynamic traffic routing implements an integrated class-of-service routing feature for extending dynamic routing to emerging services, and provides a self-healing network capability to ensure a network-wide path selection and immediate adaptation to failure. Dynamic traffic routing brings benefits to customers in terms of new service flexibility and improved service quality and reliability, at reduced cost. >

Journal ArticleDOI
TL;DR: There is much in common between the models of traffic management being devised by the IETF and ATM Forum working groups, and it is demonstrated that because of this convergence, there are a number of ways that each can take advantage of the other.
Abstract: There is much in common between the models of traffic management being devised by the IETF and ATM Forum working groups. The authors' goal is to demonstrate that because of this convergence, there are a number of ways that each can take advantage of the other. The authors discuss service models, link sharing, network provision models, traffic service class hierarchies, borrowing and replacement strategies, delays and throughput, ordering and routing with particular application to the Internet. >

Patent
28 Apr 1995
TL;DR: In this article, a method and apparatus are described which automatically allocate available physical resources of a telecommunications network to efficiently resolve network problems and improve the serviceability, availability and reliability of such networks.
Abstract: A method and apparatus are described which automatically allocate available physical resources of a telecommunications network to efficiently resolve network problems and improve the serviceability, availability and reliability of such networks. Large volumes of sensor data representing faults in the operational condition of elements of the telecommunications network are collected in a buffer. A network performance index is calculated for the entire network or for any portion of the network, thereby assembling the data into easily understood, accurate measurement of transmission performance. The network performance index is then compared with predetermined target values to determine what resources to allocate.

Journal ArticleDOI
TL;DR: In this article, the authors considered the design of material handling flow paths in a discrete parts manufacturing facility, and two efficient heuristics were proposed to determine near-optimal solutions to the resulting NP-hard problem.

Dissertation
01 Jan 1995
TL;DR: The results in this theses demonstrate the value of good problem formulations and the effectiveness of dual-ascent solution procedures that exploit a problem's special structure.
Abstract: Recent rapid technological advances (including high-capacity fiber-optic cables) in the tele-communications industry have introduced numerous opportunities for services other than traditional voice transmission. Disruptions in service for these high capacity systems can be (and have been) disastrous. For these reasons, network reliability is critical. This thesis studies the problem of topological design of survivable networks, that is, networks capable of maintaining communication capabilities in response to equipment failure. We study structural properties and develop strong formulations for a general Network Design Problem with Connectivity Requirements (NDC) and for special cases. Using these strong formulations, we devise dual-ascent methods that provide good lower bounds and heuristic solutions with performance guarantees on their degree of suboptimality. In particular: (1) We develop a dual-ascent algorithm for a very general NDC problem. This algorithm optimally solves special cases including the k-edge-disjoint path problem and the k-node-disjoint path problem. The algorithm is the most general heuristic procedure of this kind. (2) We investigate the polyhedral structure of a flow formulation for the unitary NDC problem. By projecting out the flow variables, we show that the flow-based formulation implies three new classes of valid inequalities--partition, odd-hole, and combinatorial design--for a well-known cutset formulation of the problem. (3) Using this strong formulation, we devise and empirically test a dual-ascent solution approach for the network design problem with low connectivity requirements. This algorithm requires (on average) 950 seconds of CPU time on a Sun SPARCstation 10 workstation to solve problems with up to 300 nodes and 3000 edges. The algorithm generates solutions known to be within 4 percent of optimality for typical telecommunication applications, and within 1 percent of optimality for classical Steiner tree problems. (4) We develop a new (directed) formulation for the NDC Problem. The results in this theses demonstrate the value of good problem formulations and the effectiveness of dual-ascent solution procedures that exploit a problem's special structure. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)


Proceedings ArticleDOI
14 Nov 1995
TL;DR: A new integrated network design tool (INDT) being developed in AT&T Bell Labs is described, which includes a variety of network design algorithms that encompass virtually every modern network design scenario.
Abstract: We describe a new integrated network design tool (INDT) being developed in AT&T Bell Labs. This tool includes a variety of network design algorithms that encompass virtually every modern network design scenario. INDT is intended for designing private line networks, switched voice networks, integrated private line and switched voice networks and integrated ATM based multimedia networks. All these versions come in two flavors: (i) a desert start version that designs unconstrained networks assuming no embedded base and (ii) a constrained version that takes the embedded network base as input and produces a constrained optimal network design that allows maximum reuse of the embedded network.