Institute for Systems Research Technical Reports

Permanent URI for this collectionhttp://hdl.handle.net/1903/4376

This archive contains a collection of reports generated by the faculty and students of the Institute for Systems Research (ISR), a permanent, interdisciplinary research unit in the A. James Clark School of Engineering at the University of Maryland. ISR-based projects are conducted through partnerships with industry and government, bringing together faculty and students from multiple academic departments and colleges across the university.

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Author: search.filters.author.Ball, Michael O.Subject: search.filters.subject.network management

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    Next Generation Satellite Systems for Aeronautical Communications
    (2000) Ercetin, Ozgur; Ball, Michael O.; Tassiulas, Leandros; Tassiulas, Leandros; ISR; NEXTOR
    The US airspace is reaching its capacity with the current Air Traffic Control system and a number of flights that is constantly rising, and estimated to be over 54 million per year by 2002. The FAA has undertaken several projects to modernize the National Airspace System (NAS) to ensure the safety of the increasing number of flights. Of special importance is the modernization of the Air-Ground (A/G) Communications infrastructure, which is the heart of the air traffic control (ATC).

    The current plan in the modernization of the A/G communications is to migrate from analog voice only system to integrated digital voice and data system. The next generation satellite systems can be an alternative to the terrestrial A/G systems by their low propagation and transmission delays, global coverage, high capacity, and free flight suitable characteristics. In this paper, we give an overview of the current and the future ATC architectures, describe the systems and the communications issues in these systems, and develop a framework in which LEO/MEO next generation satellite systems can be integrated to the future ATC systems.

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    Two-Path Subsets: Efficient Counting and Applications to Performability Analysis
    (1996) Ball, Michael O.; Hagstrom, Jane N.; Provan, J. Scott; ISR
    The problem of computing preformability probabilities in stochastic PERT and flow networks is studied when the networks is ﲭinimally designed to withstand any two component failures. Polynomial-time algorithms to compute preformability when the network is planar -- the nonplanar versions being NP-hard -- solve related ﲴwo-path subset problems. Given an acyclic graph with weights on the arcs, the algorithms compute the total weight of all subsets of arcs that are contained in (1) two source-sink paths or (2) two arc-disjoint source-sink paths. A polynomial algorithm is given for (1), and for (2) in the case where the graph is a source-sink planar k-flow graph, that is edge-minimal with respect to supporting k units of flow.
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    Call Rerouting in an ATM Environment
    (1995) Ball, Michael O.; Vakhutinsky, A.; ISR; CSHCN
    ATM networks must handle multiclass traffic with diverse quality of service requirements. We consider a multiclass routing model in which routes are calculated in a distributed fashion by the call origination nodes. Within this general context, we address the problem of rerouting a set of previously routed calls to avoid a failed link. Under the approach we propose, a single node executes an aggregate global rerouting of all affected calls and then converts the set of aggregate routes into an allocation of bandwidth on each link to call origination nodes for the purpose of rerouting. The bandwidth allocation is distributed to each origination node, which in turn then calculates routes for the individual calls. The problem faced by each call origination node is a variant of the so-called bandwidth packing problem. We develop and analyze an approximate algorithm for solving the problem in the specific context that arises in our setting.
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    MANDATE: MAnaging Networks using DAtabase TEchnology
    (1992) Haritsa, Jayant R.; Ball, Michael O.; Roussopoulos, N.; Datta, Anindya; ISR
    In a recent opinion poll of telecommunications executives, enterprise network management was identified to be the top technological issue of the future. At present, however, there do not exist any viable solutions to this critical problem. Therefore, considerable research efforts are being focused on the development of effective network management tools. A management information database is the heart of a network management system - it provides the interface between all functions of the network management system, and therefore has to provide sophisticated functionality allied with high performance. In this paper, we describe MANDATE (MAnaging Networks using DAtabase TEchnology), a database system that is designed to effectively support the management of large networks of the future. MANDATE uses special characteristics of network management data and transactions, together with recent advances in database technology, to efficiently derive its functionality.