Showing papers on "Network planning and design published in 1998"

Cycle-oriented distributed preconfiguration: ring-like speed with mesh-like capacity for self-planning network restoration

Abstract: Cycle-oriented preconfiguration of spare capacity is a new idea for the design and operation of mesh-restorable networks. It offers a sought-after goal: to retain the capacity-efficiency of a mesh-restorable network, while approaching the speed of line-switched self-healing rings. We show that through a strategy of pre-failure cross-connection between the spare links of a mesh network, it is possible to achieve 100% restoration with little, if any, additional spare capacity than in a mesh network. In addition, we find that this strategy requires the operation of only two cross-connections per restoration path. Although spares are connected into cycles, the method is different than self-healing rings because each preconfigured cycle contributes to the restoration of more failure scenarios than can a ring. Additionally, two restoration paths may be obtained from each pre-formed cycle, whereas a ring only yields one restoration path for each failure it addresses. We give an optimal design formulation and results for preconfiguration of spare capacity and describe a distributed self-organizing protocol through which a network can continually approximate the optimal preconfiguration state.

Urban Bus Transit Route Network Design Using Genetic Algorithm

Abstract: Urban bus route network design involves determining a route configuration with a set of transit routes and associated frequencies that achieves the desired objective. This can be formulated as an optimization problem of minimizing the overall cost (both the user's and the operator's) incurred. In this paper, the use of genetic algorithms (GAs), a search and optimization method based on natural genetics and selection, in solving the route network design problem is reported. The design is done in two phases. First, a set of candidate routes competing for the optimum solution is generated. Second, the optimum set is selected using a GA. The GA is solved by adopting the usual fixed string length coding scheme along with a new variable string length coding proposed in this study. The former assumes a solution route set size, and tries to find that many best routes from the candidate route set, using a GA. The route set size is varied iteratively to find the optimum solution. In the newly proposed variable stri...

The effect of internal parameters and geometry on the performance of back-propagation neural networks: an empirical study

Abstract: Artificial neural networks of the back-propagation type are being used increasingly for modelling environmental systems. One of the most difficult, and least understood, tasks in the design of back-propagation networks is the choice of adequate internal network parameters and appropriate network geometries. Although some guidance is available for the choice of these values, they are generally determined using a trial and error approach. This paper describes the effect of geometry and internal parameters on network performance for a particular case study. Although the information obtained from the tests carried out in this research is specific to the problem considered, it provides users of back-propagation networks with a valuable guide on the behaviour of networks under a wide range of operating conditions. The results obtained indicate that learning rate, momentum, the gain of the transfer function, epoch size and network geometry have a significant impact on training speed, but not on generalisation ability. The type of transfer and error function used was found to have a significant impact on learning speed as well as generalisation ability.

Apparatus and method for network capacity evaluation and planning

Abstract: Network capacity evaluation and planning is performed based upon the traffic across the links of the network Once a link's traffic volume has been measured, it is compared with the link's traffic capability, and the resulting parameters compared with the traffic and capability of other links of the network to create measures of network capacity and balance Then, simulated changes to the network configuration may be made by substituting simulated traffic volume amounts and capabilities for selected link traffic measurements and capabilities, and the resulting measures of network capacity and balance may then be compared to determine whether the simulated changes represent a preferred network configuration

Measuring Network Structure

Abstract: Networks have been a research issue in public administration for many years. Because of the difficulty of measuring networks, they have often been treated as a metaphor, a conceptual scheme, or a management technique (networking). The work on networks in public administration is almost all of the case study and rarely of the comparative case variety. This article presents the results of two studies of networks using social network analysis as a technique for studying structural relationships between organizations. This technique is utilized to show both the research and practical potential of network analysis as an evaluation methodology for organizations that jointly produce a service. In the first study, the network provides mental health services to seriously mentally ill adults. In the second study, the network attempts to prevent young people from abusing drugs and alcohol. The two studies were undertaken for different reasons. The first was an elaborate comparative study of four mental health networks and the relationship between network design and performance. The second was a much simpler consulting effort to help a local prevention partnership create linkages to other community organizations. However, in both of the studies the goal was to measure the structural ties in the network based on various types of relationships that exist in a given field of practice. These linkages are ties that bind the network together and become data that can be used to compare networks on their degree and type of integration. The article makes the argument that links in a network are one way that scholars can compare networks in similar or different policy domains. At the same time, the article argues that analysing linkages in an organization’s network is an effective and practical means of determining how well integrated any given organization is in a network.

Method and system for global communications network management and display of market-price information

Abstract: A system and method for flexibly routing communications transmissions in an efficient manner is disclosed. In a preferred embodiment, service providers submit information to a centralized server node which comprises cost and service parameter data for routing a communication from a first location to a second location. The server node receives all of the submitted rate information, evaluates it, and generates from the information a rate-table database comprising efficient routing paths for connecting transmissions between any two locations in a communications switching network. The server may be programmed to substantially optimize its rate-table database with respect to one or more parameters, such as price, network utilization, return traffic volumes, and others. Service requesters submit service requests to the centralized service node. The server node identifies efficient routes which meet the requesters' requirements and brokers sales of communication (or connect) time from the service providers to the service requesters. In a preferred embodiment the system is capable of displaying market-price information related to the supported communication routes to prospective sellers and buyers of connection time.

A Cutting Plane Algorithm for Multicommodity Survivable Network Design Problems

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.

Spatial traffic estimation and characterization for mobile communication network design

Abstract: This paper presents a new method for the estimation and characterization of the expected teletraffic in mobile communication networks. The method considers the teletraffic from the network viewpoint. The traffic estimation is based on the geographic traffic model, which obeys the geographical and demographical factors for the demand for mobile communication services. For the spatial teletraffic characterization, a novel representation technique is introduced which uses the notion of discrete demand nodes. We show how the information in geographical information systems can be used to estimate the teletraffic demand in an early phase of the network design process. Additionally, we outline how the discrete demand node representation facilitates the application of demand-based automatic mobile network design algorithms.

On some challenges and design choices in ad-hoc communications

Abstract: Ad-hoc networks are network architectures that can be rapidly (ideally immediately) deployed and that do not need to rely on pre-existing infrastructure. The salient feature of this breed of networks is that they can operate in different and differing propagation and network operational conditions, which cannot be predicted during the network design stage. We discuss some of the challenges and choices that need to be made while designing an ad-hoc network. In particular, we address the following three issues: hierarchical vs. flat network architectures, proactive vs. reactive (on demand) routing protocols vs. a hybrid approach, and sensing-based vs. dialog-based medium access control.

Telecommunications Network Planning

Abstract: From the Publisher: Telecommunications Network Planning will benefit both telecommunications practitioners looking for efficient methods to solve their problems and operations researchers interested in telecommunications. The book examines network design and dimensioning problems; it explores Operation Research issues related to a new standard Asynchronous Transfer Mode (ATM); it overviews problems that arise when designing survivable SDH/SONET Networks; it considers some broadband network problems; and it concludes with three chapters on wireless and mobile networks. Leading area researchers have contributed their recent research on the telecommunications and network topics treated in the volume.

Research activities on UMTS radio interface, network architectures, and planning

Abstract: Currently worldwide activities are going on to define third-generation mobile radio systems (IMT-2000 on ITU/UMTS in Europe). These systems aim to support a wide range of services from voice and low-rate data up to high-rate data services, including multimedia services, and circuit- and packet-oriented services. These systems will operate in all radio environments to provide service to anyone, anytime, anywhere. In Europe the European Commission is partly funding research activities in the ACTS framework related to third-generation systems. A spectrum-efficient multiple access scheme proposal is being developed by the ACTS FRAMES project to fulfill the requirements for terrestrial third-generation mobile radio systems. The results and proposals of FRAMES are used as input mainly to the ETSI standardization process. This radio access scheme addresses the different worldwide standardization activities where TDMA and CDMA-based solutions are currently expected. Different proposals for the UMTS system architecture and network issues are currently being discussed in the relevant standardization bodies. On one hand, the GRAN approach envisages a single UMTS access part able to connect with multiple core networks; on the other hand, the generic core network approach proposes to develop UMTS core network functionality able to handle multiple access networks, which can adopt different types of radio access techniques. The ACTS RAINBOW project presents a proposal where both approaches are unified in a system structure. From the network planning viewpoint, the major features of a third-generation mobile system are the wide variety of services provided, the high number of customers expected (especially in urban and densely populated areas), the network architecture flexibility to allow different configurations to be deployed, and the advanced mobility management strategies. From this perspective the ACTS STORMS project is elaborating new planning methodologies tailored to the specific needs of a UMTS operator, and designing and developing a set of software modules covering the whole set of disciplines involved in mobile network planning.

Airline Network Design

Abstract: The goal of this paper is to understand choices of networks and schedules by a profit maximizing airline. By "network" we mean the routing pattern for planes and by "schedule" we mean the frequency of service between cities and the amount of time put into the schedule to assure on-time arrival. This paper analyzes network and schedule choice using an "idealized" model that permits derivation of analytic, closed form expressions for airline and passenger costs. Many important conclusions are obtained. It is optimal for a profit maximizing airline to design its network and schedule to minimize the sum of airline and passenger costs. Profit maximizing choice of schedule frequency depends on the network. Direct service has lower schedule frequency than other networks. Parametric studies are performed on the effect of distance between cities, demand rate, and the number of cities served on the choice of the network. Some conclusions are: (1) If the distance between cities is very small, then direct service is optimal; otherwise, other networks, such as hub and spoke are optimal. (2) Similarly, for very high demand rates, direct service is optimal; and for intermediate values, hub and spoke is optimal. (3) If the number of cities is small, direct service dominates; and if it is large, hub and spoke is optimal. We note that any airline's schedule includes safety time as a buffer against delays, and we demonstrate that schedule reliability is highest for direct routing. Surprisingly, the amount of time that is added to the schedule to buffer delays is relatively less in direct networks than in other networks. This can explain the superior on-time performance and high equipment utilization of direct carriers such as Southwest Airlines.

A capacity paradox in network design and how to avoid it

Abstract: The network design problem is often alluded to in the transportation literature together with the spectacular example of Braess paradox, which tells us that creating a new link in a congested network or adding capacity to an existing link may actually increase network-wide congestion or user travel costs. In this note we introduce a new paradox pertaining to network design problems. Using a simple network example, we demonstrate that the addition of a new road segment to a road network may actually reduce the potential capacity of the network. We then show how this capacity paradox can be avoided by introducing the concept of network reserve capacity into network design problems.

Wide area network design: concepts and tools for optimization

Abstract: 1 Introduction 2 "Hello World" of Network Design 3 Graphs, Trees, and Tours 4 Traffic and Cost Generators 5 Access Network Design 6 Multiple Speed Access Designs 7 Multi-Center Local Access Design 8 Mesh Network Design 9 Mesh Network Design-II 10 Network Design with Constraints 11 Network Redesign 12 Closing Words Glossary

Distributed network protocols for wireless communication

Abstract: This paper describes a network design strategy that focuses on energy conservation. This position-based network protocol is optimized for minimum energy consumption in wireless networks that support peer-to-peer communication. Given any number of randomly deployed communication nodes over an area, we show that a simple local optimization scheme executed at each node guarantees strong connectivity of the entire network and attains the global minimum energy solution for both stationary and mobile networks.

Methods and apparatus for planning and managing a communications network

Abstract: A method for automatically planning and managing the performance of a communications network comprising a propagation forecasting step where propagation forrecast algorithms form a propagation forecast from weather inputs and a traffic forecasting step where traffic forecast algorithms form a traffic forecast from traffic data inputs and a network planning step where planning algorithms display an automated network model. During a forecast updating step, meteorological measurements and radio traffic measurements are continuously provided, resulting in adjusted propagation and traffic forecasts, which are then followed by a network realignment step to adjust the network. During a model comparison step, an artificial intelligence program continuously compares the model, the model adjustments, the realigned network and the network performance parameters with each other. A coefficient adjustment step adjusts the propagation, traffic and planning algorithms. In a reconfiguration instructions step, taking into account the meteorological and radio traffic measurements, the adjusted propagation forecast, the adjusted traffic forecast and network performance parameters, reconfiguration instructions are developed and transmitted to network operators. Also provided is an automated communications network planning apparatus for converting meteorological data and traffic data into a network model, capable of adjustment and updating, shown on a network terminal display.

Improved loss calculations at an ATM multiplexer

Abstract: In this paper we develop a simple and accurate analytical technique to determine the loss probability at an access node to an asynchronous transfer mode (ATM) network. This is an important problem from the point of view of admission control and network design. The arrival processes we analyze are the Markov-modulated Poisson process (MMPP) and the Markov-modulated fluid (MMF) process. These arrival processes have been shown to model various traffic types, such as voice, video, and still images, that are expected to be transmitted by ATM networks. Our hybrid analytical technique combines results from large buffer theories and quasi-stationary approaches to analyze the loss probability of a finite-buffer queue being fed by Markov-modulated sources such as the MMPP and MMF. Our technique is shown to be valid for both heterogeneous and homogeneous sources. We also show that capacity allocation based on the popular effective-bandwidth scheme can lead to considerable under-utilization of the network and that allocating bandwidth based on our model can improve the utilization significantly. We provide numerical results for different types of traffic and validate our model via simulations.

Economic design of reliable networks

Abstract: This paper describes a general approach to the optimal design of communications networks when considering both economics and reliability. The approach uses a genetic algorithm to identify the best topology of network arcs to collectively meet cost and network reliability considerations. This approach is distinct because it is highly flexible and can readily solve many versions of the network design problem, including formulations not previously seen in the literature that more closely reflect actual design scenarios. The method is shown to be effective, computationally efficient and flexible on a suite of diverse test problems.

System and method for managing a telecommunications network by determining service impact

Abstract: A system and method for managing a telecommunications network through near real time analysis of Call Detail Records (CDRs) is provided. The system and method of the invention reports how a particular call service is performing and how its performance deteriorates as a result of any type of network event, including both hardware and software related events. A feature of the invention is that it provides several levels of service impact reporting, thus providing users with more versatile and detailed network management capabilities.

Protection interoperability for WDM optical networks.

Abstract: The failure of a single optical link or node in a wavelength division multiplexing (WDM) network may cause the simultaneous failure of several optical channels. In some cases, this simultaneity may make it impossible for the higher level (SONET or IP) to restore service. This occurs when the higher level is not aware of the internal details of network design at the WDM level. We call this phenomenon "failure propagation." We analyze three types of failure propagation, called "bottleneck," "connectivity," and "multiple groups." Then we present a solution based on the definition of appropriate requirements at network design and a WDM channel placement algorithm, protection interoperability for WDM (PIW). Our method does not require the higher level to be aware of WDM internals, but still avoids the three types of failure propagation mentioned above. We finally show the result on various network examples.

Side constrained traffic equilibrium models: traffic management through link tolls.

Abstract: The criteria by which travellers choose their routes in a traffic network are, to some degree, in conflict with society’s goal of utilizing the network efficiently: a traveller can be expected to most often choose a route which minimizes a combination of travel time and expenses while society’s goal often is to have low average travel times and little damage to the environment The traffic system may be viewed as a non-cooperative Stackelberg game, in which a traffic manager, represented as the leader, changes the infrastructure so as to achieve some overall management goal with respect to the distribution of the traffic in the network The travellers are then modelled as the followers; they react to the infrastructure changes by modifying their behaviour, for example by adjusting their route choices or travel modes If the manager’s infrastructure changes are adequate, then the travellers’ response is the desired one Common means for achieving such a change in the traffic flows are to invest in traffic network capacity, to introduce traffic controls such as traffic lights and one-way traffic, to introduce tolls on some links, or some other network design measure, and to supply the travellers with information about alternative routes

Frequency assignment in cellular phone networks

Abstract: We present a graph-theoretic model for the frequency assignment problem in cellular phone networks. Obeying several technical and legal restrictions, frequencies have to be assigned to transceivers so that interference is as small as possible. This optimization problem is NP-hard. Good approximation cannot be guaranteed unless P = NP. We describe several assignment heuristics. These heuristics are simple and not too hard to implement. We give an assessment of the heuristics' efficiency and practical usefulness. For this purpose, typical instances of frequency assignment problems with up to 4240 transceivers and 75 frequencies of a German cellular phone network operator are used. The results are satisfying from a practitioner's point of view. The best performing heuristics were integrated into a network planning system used in practice.

Route optimization and traffic management in an ATM network using neural computing

Abstract: Neural computing techniques are used to optimize route selection in a communication network, such as an ATM network. Output measurements of the network are used to provide optimal routing selection and traffic management. Specifically, link data traffic is monitored in the network to obtain traffic history data. An autoregressive backpropagation neural network is trained using the traffic history data to obtain respective predicted traffic profiles for the links. Particular links are then selected for carrying data based on the predicted traffic profiles. A cost function, limits on network parameters such as link cost and cell rate, and other quality of service factors are also considered in selecting the optimal route.

OSPF Network Design Solutions

Abstract: From the Publisher: OSPF Network Design Solutions presents a detailed, applied look into the workings of the popular Open Shortest Path First protocol, demonstrating how to dramatically increase network performance, security, and the ease with which large-scale networks are maintained. OSPF is thoroughly explained through exhaustive coverage of network design, deployment, management, and troubleshooting.