Showing papers on "Network planning and design published in 1988"

Survivable network architectures for broad-band fiber optic networks: model and performance comparison

Abstract: A class of survivable network architectures and a fiber network design model to study quantitative tradeoffs between cost and survivability for each candidate network architecture are discussed. The network architectures studied fall into two categories: conventional architectures are those using present and future technologies, respectively. The model network used in this study is a metropolitan intralocal access transport area (LATA) network. For the near term, the study show that a 'single homing' architecture with 1:N diverse protection provides affordable survivability for fiber cable cuts. The percentage of model circuits protected from link failures is raised from 50%-72% for only 6.3% increase in cost. For future architectures, the self-healing rings could both improve survivability and reduce costs. >

Transit system network design

Abstract: This article formulates a transit network design model for determining frequencies of each transit line in a network. This transit network design model requires a mode-split assignment model with distinct transit lines, each with its own specified frequency, to capture the mode split effects of increases or decreases in individual transit line frequencies. It is shown how to refine conventional mode-split assignment models to include this feature. The resulting model includes more precise measures of transit access and transfer delays, so that it more accurately predicts mode choices and link flows. This variation of the mode-split assignment model uses Dial's transit loader to solve Frank-Wolfe subproblems, using frequencies of individual transit lines to find fastest transit paths, considering access time, ride time, and any transfer delays. Computational shortcuts using the standard Hooke-Jeeves algorithm are demonstrated.

A fast packet switch for the integrated services backbone network

Abstract: With the projected growth in demand for bandwidth and telecommunication services will come the requirement for a multiservice backbone network of far greater efficiency, capacity, and flexibility than ISDN (integrated-services digital network) is able to satisfy. This class of network has been termed the broadband ISDN, and the design of the switching nodes of such a network is the subject of much research. The author investigates one possible solution. The design and performance, for multiservice traffic, is presented for a fast packet switch based on a nonbuffered, multistage interconnection network. It is shown that for an implementation in current CMOS technology, operating at 50 MHz, switches with a total traffic capacity of up to 150 Gb/s can be constructed. Furthermore, if the reserved service traffic load is limited on each input port to a maximum of 80% of switch port saturation, then a maximum delay across the switch of on the order of 100 mu s can be guaranteed, for 99% of the reserved service traffic, regardless of the unreserved service traffic load. >

On the Evaluation of Telecommunications Network Reliability Using Routing Models

Abstract: A reliability measure that takes into account routing and rerouting policies after failures as well as the capacity of the network to satisfy its demand is proposed. The measure, based on the evaluation of the lost call traffic, needs resolution of a routing model for the states of perfect functioning as well as the most probable failure states. A type of routing model useful for network planning is also proposed. The model is closer to reality and easier to implement than the other classical multicommodity formulations. A convex-simplex implementation with a reoptimization feature explicitly adapted to the proposed model is used. >

The Minimum‐Covering/Shortest‐Path Problem*

Abstract: Due to the inherent multiobjective nature of many network design and routing problems, there has been a tremendous increase in multiobjective network modeling in recent years. In this article we introduce one such model, the minimum-covering/shortest-path (MinCSP) problem, and formulate several variations of the problem. The MinCSP problem is a two-objective path problem: minimization of the total population negatively impacted by the path and minimization of the total path length. A population is considered to be negatively impacted by the path if the path comes within some predetermined distance of the population. Consequently, the MinCSP problem extends the concept of coverage from facility location modeling to network design. Additionally, several existing solution methods for the problem are briefly discussed and potential applications presented.

Distributed data communication networks for real-time process control

Abstract: The paper deals with the performance analysis of network access protocols for distributed data communication and control systems (DDCCS) in chemical and processing plants. The selection of an appropriate data highway protocol is an important step in the DDCCS network design for large-scale processes because the real-time feedback control loops are subject to time-varying delays resulting from data latencies and possible mis-synchronism between system components. SAE token ring, SAE linear token bus, and MIL-STD-1553B protocols have been analyzed in view of the DDCCS network design requirements. The results of closed loop control system simulations are presented to demonstrate how data latency generated by the network access protocols could degrade the dynamic performance of the controlled process.

Intelligent network/2: The architecture-The technical challenges-The opportunities

Abstract: The Intelligent Network/2 (IN/2) architecture concept diverges from the traditional new service introduction approach by distributing call-processing capabilities across multiple network modules, by constructing network services with service-independent capabilities, and by using standard signaling protocols among the network elements. The IN/2 approach provides opportunities to implement new services while reducing the service introduction interval. The IN/1 architecture provides new-service introduction from a centralized point, allowing users throughout a wide geographic area to have access to the service simultaneously. The IN/2 concept extends the IN/1 approach and sharply reduces the new-service introduction interval. IN/2 applies the premise that multiple network services or service features can be constructed from a set of reusable network capabilities, which apply to many services and are therefore independent of a particular service application. An overview of the IN/2 architecture is presented, highlighting the key technical issues. >

Computer-Aided Line Network Design (DIANA) and Minimization of Transfer Times in Networks (FABIAN)

Abstract: Line network, service frequencies, the conditions for transfer passengers as well as the tariff-structure are fundamentals in the description of service levels in public transport. These features — separately and together — have a strong influence on the attractiveness as well as the economic viability of a public transport system. Within the various tasks to plan and control public transport, fig.1 shows these tasks which are summarized in the step “traffic engineering”.

Impact of the intelligent network on the capacity of network elements

Abstract: The effect that integration of the intelligent network (IN) concept into the existing network architecture has on the capacity of the various network elements is addressed. The effect of excessive load on that and other existing services is also examined. The discussion covers: methods of characterizing capacity and performance; major causes of increased load with the IN; perception of increased delay by the user; effect of delay on service introduction; and methods of improving IN performance. The example of the call-forwarding service is used to show the effect that IN can have on the performance of services, as perceived from the delays experienced by the user. >

A neuromorphic approach to adaptive digital circuitry

Abstract: A design for an adaptive digital circuit based on neuromorphic (brain-inspired) architecture is proposed The neuromorphic model used is a two-layered perceptron that utilizes a form of least-mean-square error correction in order to learn appropriate internal representations necessary to accomplish the mapping of binary input vectors into desired binary output vectors The proposed network design differs from the theoretical model in that limited density between layers and quantized parameter values are used to facilitate VLSI fabrication Simulation results indicate that the simplified version of the network behaves in ways similar to the fully connected, floating-point network with approximately the same number of elements in the middle layer Circuits which are designed with neural-inspired, cellular topology would have the advantage of high fault tolerance, since information is stored in neural networks in a distributed, rather than a local, fashion >

Effects of road pricing on system performance

Abstract: This paper investigates the effects of road pricing on system performance and describes two facts about flow pattern in a transportation system. The first, illustrated by an example of Braess paradox, is that adding a new link to the network does not necessarily minimise the total travel time. The second is that the introduction of appropriate toll pricing may reduce not only the total network time, but also the travel time for each individual traveller. It follows with the investigations of different system objectives and different pricing policies (only toll pricing and distance-based pricing are considered), and shows how they affect the system performance and flow pattern. Lastly, three different assignment methods are compared and an equilibrium assignment method is proposed for network design.

Operations planning for the information age (telecommunication networks)

Abstract: The need for integration of network and operations planning is discussed. A functional planning approach is suggested, and a current functional plan for near-term operations is presented. A functional approach to longer range operations is then discussed, starting with a list of desired attributes for the next-generation network. These attributes are analyzed with respect to the demands they make on architecture and operations functions. >

Optimum routing for fiber network design: model and applications

Abstract: The authors propose a model to globally optimize topology and routing for survivable fiber networks. Numerical experiments show that the integer program approach for the routing model is computationally attractive for the intra-LATA fiber-hubbed network design using the DS3 as the basic routing unit and terminal multiplexers. The experiments also provide quantitative support for arguments that the hubbing network architecture and hub routing are an appropriate alternative architecture and approximation routing model, respectively, under the projected telephone demand and fiber technology environments. It is also found that the appropriate network architecture for future broadband ISDNs is likely to be determined by DS3 demand requirement along with optimization of tradeoffs between fiber cost and route mileage cost. >

Circuit network design under reliability constraints

Abstract: The network design problem with reliability constraints is a problem where given a finite set of nodes; the objective is a cost efficient selection of node links and link capacities sufficient to satisfy the node to node traffic demands in normal and failed conditions. In this paper, the authors present a general mathematical model for this problem and a revised formulation which seems particularly appropriate for fiberoptics networks. They also describe upper and lower bounding procedures based on continuous relaxations of this modified formulation. Preliminary computational results are reported; they seem to indicate that the proposed bounds might prove suitable for a branch-and-bound approach of the problem. (A)

Transmission-System Design

Abstract: This paper describes some of the complexities of designing high-pressure gas-transmission systems. The contribution of OR to efficient gas-transmission-system design is discussed. A new network design program is described to illustrate the benefits of models to system design and plant selection.

EUnet and OSI transition plans

Abstract: EUnet, a pan-European cooperative R&D network, is described in terms of applications, protocols and topology. A strategy for the introduction of OSI applications and protocols into this network is then presented.

Traffic engineering operations for the ACCUNET packet service network

Abstract: 1PSS packet switches have been deployed across the continental United States to provide the ACCUNET packet service (APS). The authors describe the operations environment that provides traffic-engineering support functions for the 1PSS network. Methods and procedures used for traffic data collection, service evaluation, forecasting and planning are described. It is concluded that centralization of traffic-engineering operations makes global functions such as network servicing and planning possible. The traffic-engineering functions supply the user with many levels of detail, from reports that only identify overloaded components to reports that describe detailed engineering changes. These functions help the network engineer to minimize network costs and provide the desired levels of service. >

On Use of 802.4 Token Bus in Distributed Control Systems

Abstract: IEEE 802.4 broadband channel access scheme has been widely accepted as the standard for factory Local-Area Networks. The priority option of the 802.4 standard supports multiple classes of traffic by using a set of timers to control information exchange. A timer assignment technique is presented for factory LANs using the 802.4 priority option. The timers are set to satisfy the worst case access delay requirements of real-time control applications. Other applications that are not time constrained can be supported simultaneously. In fact, under certain conditions, such applications can also be guaranteed a minimum bandwidth allocation. The results given here can be used during network design stage to ensure that the network can support the requirements of the devices connected to the network. Simulation results are used to evaluate the timer assignment scheme.

Methods for traffic matrix forecasting

Abstract: The key word for the thesis is long-term demand forecasting which have been applied on telecommunications and especially on broadband accesses and traffic.The objective with the thesis has been to structure and present work on long-term broadband forecasting, to evaluate the forecasting results and to extract the learning. Each main chapter ends with a section called experiences and conclusions.The thesis is organized in seven main parts.The first part addresses application of the Delphi technique for long term forecasting broadband accesses. Three Delphi surveys, which have been conducted during a long period, have been evaluated. All three Delphi surveys have used similar procedures in carrying out the survey, except that two of the Delphi surveys were postal surveys, while one was carried out on site. The applied procedure is evaluated based on an important reference article on Delphi surveys and also based on the long-term forecasting results. The Delphi surveys are not very often used. Hence, the description of the way to conduct the surveys and the experiences and also the evaluations of the results are given specific attention in the thesis.The second part of the thesis has the title “Long-term broadband technology forecasting”. Results from three papers are presented and evaluated. The papers show the evolution of the forecasting modelling. The first forecasts for the broadband evolution in Western Europe were made before broadband was introduced in the residential market in Western Europe. The long-term forecasts were developed based on Logistic models. The modelling also includes substitution effects between broadband technologies. Experiences have shown that technological knowledge and techno-economic evaluations are crucial for making long-term broadband forecasts. Some attention is also put on available broadband accesses statistics and an approach to separate aggregated broadband statistics to access statistics for the business market and for the residential market.“Long-term forecasting models for cost components and technologies” is the third part in the thesis. To be able to evaluate broadband technologies, techno-economic calculations of the “economic” value of the relevant broadband technologies are very important. The extended learning curve model invented by Borgar T Olsen and Kjell Stordahl is presented. The model is much more powerful than the simple exponential learning curve. The extended learning curve makes long-term forecasts of component costs and has the ability to be used directly on technoeconomic calculations, as opposed to the traditional learning curve model, which does not predict the cost as a function of time. In addition the extended learning curve model has interpretable parameters. It is shown that the model may utilize a priori information in cases where too few observations are available.The fourth part addresses long-term traffic forecasting. Three papers are enclosed. The chapter starts with a short overview of relevant forecasting models. Then attention is paid to forecasting and network planning. A comprehensive overview of the field is given together with numerous references in the enclosed paper “Forecasting – an important factor for network planning”. Longterm forecasts for the core network is analyzed and discussed. Also some figures for the total broadband traffic evolution in the Norwegian core network is presented. The last paper described in the chapter shows how long-term traffic forecasts on aggregated level can be used for traffic matrix forecasting by using the extended weighted least square method. The chapter ends by listing several important drivers for new and enhanced broadband traffic that are important in traffic forecasting models.

Demand assignment for mobile radio networks over satellite

Abstract: Mobile satellite communication systems are expected to be introduced widely during the 1990s, offering public telephone, private radio and data messaging services to a potentially large number of mobile users. Due to the narrow bandwidth in the L-band allocated specifically for land-mobile satellite services, demand-assigned multiple access (DAMA) is an important element in network design. A DAMA design approach is presented that addresses specifically the characteristics of a dispatch mobile radio network, in which the dispatcher is often the resource bottleneck. Preliminary analysis shows that the proposed design offers advantages in satellite channel utilization and DAMA signaling overhead compared to previously proposed designs. >

GTE common channel signaling network design and deployment planning

Abstract: Common channel signaling (CCS) message network configuration analysis results are presented related for Signalnet, GTE's shared CCS network. A design tool based on a linear programming model performing mixed integer optimization is described and used to solve the topological design problem. This tool is used to determine the number of signal transfer points (STPs) required in the network, where they should be located, and service switching point (SSP) homing on STP's. Hypothetical snapshots of the network in 1989, 1992, and 1996 are presented, including an optimal two-level hierarchy of regional and local STPs. >

LAN management system for the McDonnell Aircraft Company's manufacturing operations

Abstract: The authors present the design and implementation of a network management system (NMS) capable of monitoring an Ethernet/IEEE 802.3-based, multivendor, multiprotocol network. This NMS currently provides notification of cable plant, network component, and node failures. However, as the system was designed it became apparent that network and computer statistics, network design, and parts inventory could also be incorporated into the system. Features described include the database, the graphics workstation, information logging, and artificial intelligence. Future plans for this system are described. >