Showing papers on "Network planning and design published in 2002"

Network design consideration for distributed control systems

Abstract: This paper discusses the impact of network architecture on control performance in a class of distributed control systems called networked control systems (NCSs) and provides design considerations related to control quality of performance as well as network quality of service. The integrated network-control system changes the characteristics of time delays between application devices. This study first identifies several key components of the time delay through an analysis of network protocols and control dynamics. The analysis of network and control parameters is used to determine an acceptable working range of sampling periods in an NCS. A network-control simulator and an experimental networked a machine tool have been developed to help validate and demonstrate the performance analysis results and identify the special performance characteristics in an NCS. These performance characteristics are useful guidelines for choosing the network and control parameters when designing an NCS.

Harmony Search Optimization: Application to Pipe Network Design

Abstract: The Pipe network design problem is considered by choosing least-cost diameter pipes to satisfy flow demands and minimum head restrictions. Harmony and innovation are brought together as in music to devise a search pattern that can identify a large number of local optima in pipe network design. Improvization is brought in by varying the pitch rate parameter, and harmony is maintained by accumulating improving solutions. Because in pipe networks optimization by its very nature removes any redundancy, a minimum power loss criterion is introduced to enhance feasibility. The efficacy of the algorithm is demonstrated by solving a test nonlinear program and a pipe network problem from the literature to global optimum. Several near-optimal solutions are reported.

Method, apparatus and software for network traffic management

Abstract: A network traffic evaluation device is provided that may be used to warn of or prevent trafficabnormalities such as denial of service attacks. The device includes a data interface to receive one or both of network traffic and data indicative of characteristics of network traffic. The network traffic and/or data received by the data interface is processed for predeterminedcharacteristics that indicate that the network traffic contains a subset of attack traffic. Upon detection of the predetermined characteristics information defining a superset is provided. The superset is a portion of the network traffic that contains the subset and defines network traffic that may be redirected and/or blocked by a network device.

An ad hoc network with mobile backbones

Abstract: A mobile ad hoc network (MANET) is usually assumed to be homogeneous, where each mobile node shares the same radio capacity. However, a homogeneous ad hoc network suffers from poor scalability. Recent research has demonstrated its performance bottleneck both theoretically and through simulation experiments and testbed measurement Building a physically hierarchical ad hoc network is a very promising way to achieve good scalability. In this paper, we present a design methodology to build a hierarchical large-scale ad hoc network using different types of radio capabilities at different layers. In such a structure, nodes are first dynamically grouped into multihop clusters. Each group elects a cluster-head to be a backbone node (BN). Then higher-level links are established to connect the BN into a backbone network. Following this method recursively, a multilevel hierarchical network can be established. Three critical issues are addressed in this paper. We first analyze the optimal number of BN for a layer in theory. Then, we propose a new stable clustering scheme to deploy the BN. Finally LANMAR routing is extended to operate the physical hierarchy efficiently. Simulation results using GloMoSim show that our proposed schemes achieve good performance.

Network traffic generation and monitoring systems and methods for their use in testing frameworks for determining suitability of a network for target applications

Abstract: A system for monitoring traffic on a network first discovers the network so as to map the various devices and links in the network. Statistics are then gathered from various points in the network relating to quality of service, and especially loads on the network devices. Synthetic calls are generated at selected points of the network while monitoring the network. This data is then stored and displayed in a manner that is easy for the operator to analyze, with more detailed displays being available through the use of a mouse or keystrokes.

Composite Variable Formulations for Express Shipment Service Network Design

Abstract: In this paper we describe a new approach to solving the express shipment service network design problem. Conventional polyhedral methods for network design and network loading problems do not consistently solve instances of the planning problem we consider. Under a restricted version of the problem, we transform conventional formulations to a new formulation using what we termcomposite variables. By removing flow decisions as explicit decisions, this extended formulation is cast purely in terms of the design elements. We establish that its linear programming relaxation gives stronger lower bounds than conventional approaches. We apply this composite variable formulation approach to the UPS Next Day Air delivery network and demonstrate potential annual cost savings in the hundreds of millions of dollars.

Optimal Route Network Design for Transit Systems Using Genetic Algorithms

Abstract: The paper proposes a technique for the development of "optimal" transit route networks (for example, a bus route network) given the information on link travel times and transit demand. The proposed method, unlike previous techniques, primarily uses optimization tools for the development of the transit route network--the reliance on heuristics is minimal. In the proposed method, genetic algorithms, an evolutionary optimization technique, is used to develop the "optimal" set of routes. Results show that the proposed procedure performs better than the existing techniques.

Benefit distribution and equity in road network design

Abstract: In the classical continuous network design problem, the optimal capacity enhancements are determined by minimizing the total system cost under a budget constraint, while taking into account the route choice behavior of network users. Generally the equilibrium origin–destination travel costs for some origin–destination (O–D) pairs may be increased after implementing these optimal capacity enhancements, leading to positive or negative results for network users. Therefore, the equity issue about the benefit gained from the network design problem is raised. In this paper, we examine the benefit distribution among the network users and the resulting equity associated with the continuous network design problem in terms of the change of equilibrium O–D travel costs. Bilevel programming models that incorporate the equity constraint are proposed for the continuous network design problem. A penalty function approach by embodying a simulated annealing method is used to test the models for a network example.

On capacitated network design cut-set polyhedra

Abstract: This paper provides an analysis of capacitated network design cut–set polyhedra. We give a complete linear description of the cut–set polyhedron of the single commodity – single facility capacitated network design problem. Then we extend the analysis to single commodity – multifacility and multicommodity – multifacility capacitated network design problems. Valid inequalities described here are applicable to directed network design problems with any number of facility types and any level of capacities. We report results from a computational study done for testing the effectiveness of the new inequalities.

A reserve capacity model of optimal signal control with user-equilibrium route choice

Abstract: In this paper, we combine the concept of reserve capacity with the continuous equilibrium network design problem. An integrated method is used to maximize the reserve capacity of a road network. On the one hand we try to find the maximum possible increase in traffic demand by setting traffic signals at individual intersections. On the other hand, we increase the road capacity in order to increase the whole capacity of a road network. A bilevel programming model and heuristic solution algorithm based on sensitivity analysis are proposed to model the reserve capacity problem of optimal signal control with user-equilibrium route choice. The applications of the model and its algorithm are illustrated with two numerical examples.

Application of evolutionary algorithms for the planning of urban distribution networks of medium voltage

Abstract: Currently, an important issue in power distribution is the need to optimize medium voltage (MV) networks serving urban areas. This paper shows how an evolutionary algorithm can be used as the basis for the type of efficient algorithm such optimization demands. The search for optimal network solution will be restricted to a graph defined from the urban map, so each graph branch represents a trench. The solution space (networks) is assumed with "loop feeder circuits": networks with two electrical paths from the high voltage/medium voltage (HV/MV) substations to the customers. In the optimization process, the investment and loss load costs are considered taking into account the constraints of conductor capacities and voltage drop. The investment costs will take into account that some cables can be lying in the same trench. The process was applied for a Spanish city of 200,000 inhabitants.

Advances in optical network design with p-cycles: joint optimization and pre-selection of candidate p-cycles

Abstract: We address two open and inter-related issues about the design of p-cycle based networks. One of these is to reduce the complexity of solving optimal p-cycle design problems, making it practical to continually re-optimize a p-cycle based network in service, adapting to changing demand patterns. The second advance is a first research use of the above solution technique to study how the efficiency of a p-cycle network increases under joint optimization of the working path routes with p-cycle placement.

Traffic analysis for on-chip networks design of multimedia applications

Abstract: The objective of this paper is to introduce self-similarity as a fundamental property exhibited by the bursty traffic between on-chip modules in typical MPEG-2 video applications. Statistical tests performed on relevant traces extracted from common video clips establish unequivocally the existence of self-similarity in video traffic. Using a generic communication architecture, we also discuss the implications of our findings on on-chip buffer space allocation and present quantitative evaluations for typical video streams. We believe that our findings open up new directions of research with deep implications on some fundamental issues in on-chip network design for multimedia applications.

An improved branch-exchange algorithm for large-scale distribution network planning

Abstract: Design of optimal layout for medium-voltage power networks is a common issue in electrical distribution planning Technical constraints (radial structure, voltage drops, and equipment capacity), and reliability limits must be fulfilled The function for minimizing includes investments, power losses, and quality of supply costs The authors present in this paper an improved algorithm based on a branch-exchange technique to solve large-scale problems A heuristic algorithm for solving a Euclidean Steiner problem is used to improve the network by including transshipment nodes

DWDM Network Designs and Engineering Solutions

Abstract: A comprehensive book on DWDM network design and implementation solutionsDesign Software Included Study various optical communication principles as well as communication methodologies in an optical fiber Design and evaluate optical components in a DWDM network Learn about the effects of noise in signal propagation, especially from OSNR and BER perspectives Design optical amplifier-based links Learn how to design optical links based on power budget Design optical links based on OSNR Design a real DWDM network with impairment due to OSNR, dispersion, and gain tilt Classify and design DWDM networks based on size and performance Understand and design nodal architectures for different classification of DWDM networks Comprehend different protocols for transport of data over the DWDM layer Learn how to test and measure different parameters in DWDM networks and optical systemsThe demand for Internet bandwidth grows as new applications, new technologies, and increased reliance on the Internet continue to rise. Dense wavelength division multiplexing (DWDM) is one technology that allows networks to gain significant amounts of bandwidth to handle this growing need. DWDM Network Designs and Engineering Solutions shows you how to take advantage of the new technology to satisfy your network's bandwidth needs. It begins by providing an understanding of DWDM technology and then goes on to teach the design, implementation, and maintenance of DWDM in a network. You will gain an understanding of how to analyze designs prior to installation to measure the impact that the technology will have on your bandwidth and network efficiency. This book bridges the gap between physical layer and network layer technologies and helps create solutions that build higher capacity and more resilient networks.Companion CD-ROM The companion CD-ROM contains a complimentary 30-day demo from VPIphotonics™ for VPItransmissionMaker™, the leading design and simulation tool for photonic components, subsystems, and DWDM transmission systems. VPItransmissionMaker contains 200 standard demos, including demos from Chapter 10, that show how to simulate and characterize devices, amplifiers, and systems.

A Mathematical Model and Descent Algorithm for Bilevel Traffic Management

Abstract: We provide a new mathematical model for strategic traffic management, formulated and analyzed as a mathematical program with equilibrium constraints (MPEC). The model includes two types of control (upper-level) variables, which may be used to describe such traffic management actions as traffic signal setting, network design, and congestion pricing. The lower-level problem of the MPEC describes a traffic equilibrium model in the sense of Wardrop, in which the control variables enter as parameters in the travel costs. We consider a (small) variety of model settings, including fixed or elastic demands, the possible presence of side constraints in the traffic equilibrium system, and representations of traffic flows and management actions in both link-route and link-node space.For this model, we also propose and analyze a descent algorithm. The algorithm utilizes a new reformulation of the MPEC into a constrained, locally Lipschitz minimization problem in the product space of controls and traffic flows. The reformulation is based on the Minty (1967) parameterization of the graph of the normal cone operator for the traffic flow polyhedron. Two immediate advantages of making use of this reformulation are that the resulting descent algorithm can be operated and established to be convergent without requiring that the travel cost mapping is monotone, and without having to ever solve the lower-level equilibrium problem. We provide example realizations of the algorithm, establish their convergence, and interpret their workings in terms of the traffic network.

Network Design for Express Shipment Delivery

Abstract: Service network design problems arise at airlines (passenger and cargo), trucking companies, railroads, etc., wherever there is a need to determine cost minimizing routes and schedules, given constraints on resource availability and level of service. We focus on a particular service network design application, namely, the express shipment delivery problem, and we develop models and a solution technique designed specifically for large-scale express delivery problems with time windows. Using data from an express delivery company, we demonstrate that our approach can produce savings in total operating costs and provide a valuable tool for making decisions at strategic and tactical levels.

A flow-based model for internet backbone traffic

Abstract: Our goal is to design a traffic model for uncongested IP backbone links that is simple enough to be used in network operation, and that is protocol and application agnostic in order to be as general as possible. The proposed solution is to model the traffic at the flow level by a Poisson shot-noise process. In our model, a flow is a generic notion that must be able to capture the characteristics of any kind of data stream. We analyze the accuracy of the model with real traffic traces collected on the Sprint IP backbone network. Despite its simplicity, our model provides a good approximation of the real traffic observed in the backbone and of its variation. Finally, we discuss three applications of our model to network design and management.

Low-energy wireless communication network design

Abstract: Energy-efficient wireless communication network design is an important and challenging problem. Its difficulty lies in the fact that the overall performance depends, in a coupled way, on the following subsystems: antenna, power amplifier, modulation, error control coding, and network protocols. In addition, given an energy constraint, improved operation of one of the aforementioned subsystems may not yield better overall performance. Thus, to optimize performance one must account for the coupling among the above subsystems and simultaneously optimize their operation under an energy constraint. In this article we present a generic integrated design methodology that is suitable for many kinds of mobile systems and achieves global optimization under an energy constraint. By pointing out some important connections among different layers in the design procedure, we explain why our integrated design methodology is better than traditional design methodologies. We present numerical results of the application of our design methodology to a situational awareness scenario in a mobile wireless network with different mobility models. These results illustrate the improvement in performance that our integrated design methodology achieves over traditional design methodologies, and the tradeoff between energy consumption and performance.

Managing capacity for telecommunications networks under uncertainty

Abstract: The existing telecommunications infrastructure in most of the world is adequate to deliver voice and text applications, but demand for broadband services such as streaming video and large file transfer (e.g., movies) is accelerating. The explosion in Internet use has created a huge demand for telecommunications capacity. However, this demand is extremely volatile, making network planning difficult. In this paper, modern financial option pricing methods are applied to the problem of network investment decision timing. In particular, we study the optimal decision problem of building new network capacity in the presence of stochastic demand for services. Adding new capacity requires a capital investment, which must be balanced by uncertain future revenues. We study the underlying risk factor in the bandwidth market and then apply real options theory to the upgrade decision problem. We notice that sometimes it is optimal to wait until the maximum capacity of a line is nearly reached before upgrading directly to the line with the highest known transmission rate (skipping the intermediate lines). It appears that past upgrade practice underestimates the conflicting effects of growth and volatility. This explains the current overcapacity in available bandwidth. To the best of our knowledge, this real options approach has not been used previously in the area of network capacity planning. Consequently, we believe that this methodology can offer insights for network management.

Facilitating realtime information interexchange between a telecommunications network and a service provider

Abstract: Methods, systems, and arrangements facilitate information interexchange between a telecommunications network and an information service provider. For example, a business-to- business (B2B) engine includes one or more logic modules for and interfacing with the telecommunications network and with the information service provider. The B2B engine facilitates the reporting of, e.g., realtime information from the telecommunications network to the information service provider. This realtime information may include subscriber unit location and may be acquired and/or reported based on a mapping data structure in, e.g., the B2B engine. The data structure maps a service class to one or more parameters that dictate or provide guidance with respect to which parameters are relevant, as well as their respective values, and a mechanism for achieving the stipulated parameters. The mechanism may include specific network nodes/entities as well as frequency of acquisition to thereby enable location-tailored content data and/or services to be provided to a subscriber.

Network pricing optimization in multi-user and multimodal context with elastic demand

Abstract: Network Pricing Optimization (NPO) is formulated first as a Network Design Problem (NDP) where the design variables are tolls, the objective function is the Social Surplus and the equilibrium constraint is any current multi-user multimodal stochastic traffic assignment model with elastic demand up to trip generation and asymmetric arc cost function Jacobian. NPO is then formulated also as an Efficient Allocation Problem (EAP), where an optimal flow pattern, the System Optimum (SO), is sought and tolls are consistently determined. Necessary and sufficient conditions for the solutions to both problems are stated, showing the validity of the marginal pricing principle in the context considered.

A Constant-Factor Approximation Algorithm for the Multicommodity

Abstract: We present the first constant-factor approximation algorithm for network design with multiple commodities and economies of scale. We consider the rent-or-buy problem, a type of multicommodity buy-at-bulk network design in which there are two ways to install capacity on any given edge. Capacity can be rented, with cost incurred on a per-unit of capacity basis, or bought, which allows unlimited use after payment of a large fixed cost. Given a graph and a set of source-sink pairs, we seek a minimum-cost way of installing sufficient capacity on edges so that a prescribed amount of flow can be sent simultaneously from each source to the corresponding sink.Recent work on buy-at-bulk network design has concentrated on the special case where all sinks are identical; existing constant-factor approximation algorithms for this special case make crucial use of the assumption that all commodities ship flow to the same sink vertex and do not obviously extend to the multicommodity rent-or-buy problem. Prior to our work, the best heuristics for the multicommodity rent-or-buy problem achieved only logarithmic performance guarantees and relied on the machinery of relaxed metrical task systems or of metric embeddings. By contrast, we solve the network design problem directly via a novel primal-dual algorithm.

Quantitative approaches to distribution logistics and supply chain management

Abstract: 1: Supply Chain Management.- Examining Supply Chains from Practice.- Valuing Time in Make-to-stock Manufacturing: Calculating the Limits of Time-based Competition.- Internal Pricing in Supply Chains.- 2: Reverse Logistics.- Closed-loop Supply Chains.- Extended Design Principles for Closed Loop Supply Chains: Optimising Economic, Logistic and Environment al Performance.- A Behavioral Approach for Logistics System Analy sis and Design: A Reverse Logisti cs Case.- Performance of MRP in Product Recovery Systems with Demand, Return and Leadtime Uncertainties.- One and Two Way Packaging in the Dairy Sector.- 3: Distribution Logistics and E-Commerce.- The Logistics Behind the Enter Click.- Distribution Planning with Specific Delivery Time Restrictions for the Handling of Electronic Customer Orders in Food/Non-Food Retail Trade.- An Analysis of a Combinatorial Auction.- 4: Warehouse Location and Network Planning.- The Practice of Distribution Network Planning: Coping with Shortcomings in Important Data Quality.- A Greedy Heuristic for a Three-level Multi-period Single-sourcing Problem.- Combinatorial Optimisation Problems of the Assignment Type and a Partitioning Apprach.- 5: Vehicle Routing and Transportation.- The Vehicle Routing Problem with Time Windows and Simultaneous Pick-up and Delivery.- The Application of a Vehicle Routing Model to a Waste Collection Problem: Two Case Studies.- Strategic Vehicle Routing Problems in Practice - A pure Software Problem or a Problem Requiring Scientific Advice? Routing Problems of Daily Deliveries to the Same Customers.- 6: Warehousing.- Design of a 2-Stations Automated Guided Vehicle System.- On-line versus Off-line Control with Multi-load Vehicles.- 7: Inventory Control.- Average Costs versus Net Present Value: A Comparison for Multi-source Inventory Models.- Safety Stocks in Capacity-constrained Production Systems.- Approximations for the Waiting Time in (8, nQ)-Inventory Models for Different Types of Consolidation Policies.- List of Contributors.

Power-efficient Interconnection Networks: Dynamic Voltage Scaling with Links

Abstract: Power consumption is a key issue in highperformanceinterconnection network design. Communicationlinks, already a aignificant consumer of power now,will take up an ever larger portion of the power budgetas demand for network bandwidth increases. In this paper,we motivate the use of dynamic voltage scaling (DVS)for links, where the frequency and voltage of links are dynamicallyadjusted to minimize power consumption. Wepropose a history-based DYS algorithm that jjlidiciously adjustsDVS poIicies based on past link utilization. Despitevery conservative assumptions about DVS link characteristics,our approach realizes up to 4.5X power savings (3.2Xaverage), with just an average 27.4% Iatency increase and2.5% throughput reduction. To the best of our knowledge,this is the first study that targets dynamic power optimizationof interconnection networks.

Next generation wireless LAN system design

Abstract: An important issue in the widespread deployment of infrastructure based wireless local area networks (WLANs) is the network design. In this paper, we propose a new WLAN design approach that focuses on assuring sufficient data rate capacity to meet expected user demand in the coverage area, while still satisfying signal coverage and interference level requirements. Noting the low cost of WLAN access points, we formulate a novel mathematical network design model within the framework of constraint satisfaction problems. Our model is termed the capacity based WLAN constraint satisfaction problem (Cap-WLAN CSP). The solution of the Cap-WLAN CSP model yields a network design based on data rate demand by providing the access point locations, the frequency channel allocation, and power levels required for the WLAN to meet expected user demands. Our numerical results illustrate that the capacity based approach is more appropriate for the design of WLAN systems than those of traditional coverage based designs.

Parking Capacity and Pricing in Park'n Ride Trips: A Continuous Equilibrium Network Design Problem

Abstract: In this paper we consider the problem of designing parking facilities for park'n ride trips. We present a new continuous equilibrium network design problem to decide the capacity and fare of these parking lots at a tactical level. We assume that the parking facilities have already been located and other topological decisions have already been taken. The modeling approach proposed is mathematical programming with equilibrium constraints. In the outer optimization problem, a central Authority evaluates the performance of the transport network for each network design decision. In the inner problem a multimodal traffic assignment with combined modes, formulated as a variational inequality problem, generates the share demand for modes of transportation, and for parking facilities as a function of the design variables of the parking lots. The objective is to make optimal parking investment and pricing decisions in order to minimize the total travel cost in a subnetwork of the multimodal transportation system. We present a new development in model formulation based on the use of generalized parking link cost as a design variable. The bilevel model is solved by a simulated annealing algorithm applied to the continuous and non-negative design decision variables. Numerical tests are reported in order to illustrate the use of the model, and the ability of the approach to solve applications of moderate size.