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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    A Resource Reservation Scheme for Synchronized Distributed Multimedia Sessions
    (1997) Zhao, W.; Tripathi, S.K.; ISR
    Guarantees of services in a networked environment are provided, by the proper allocation and utilization of network and system resources.

    In this paper, we propose a resource reservation scheme for a class of, multimedia applications. We characterize this class of multimedia applications as synchronized distributed multimedia sessions, which we, believe represent a large number of multimedia applications.

    In addition to this particular class of applications, the reservation, scheme can also be applied to other applications with synchronized resource requirements. Mechanisms are devised so that, the scheme can find a feasible reservation whenever one exists, in, contrast to existing protocols where request can fail unpredictably, even when there is available resource. Based upon a layer of resource abstraction, the scheme suits well with today's heterogeneous network environment.

      A copy of this report has been published in the proceedings of
      The 1st Annual Advanced Telecommunications/Information Distribution Research Program Conference, January 21-22, 1997.
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    Admission Control Schemes for Spot-Beam Satellite Networks
    (1993) Ramseier, S.; Ephremides, Anthony; ISR; CSHCN
    In this report, we consider communication networks with a satellite with multiple spot beams. We describe the structure and features of these networks, and we consider admission control schemes which optimize the network revenue if several services types with different revenues are present. We show that in some cases the blocking of some calls even if capacity is available can considerably increase the network revenue. We will point out, however, that complete sharing, i.e., accepting calls on a first- come, first-served basis, is optimum for systems with similar traffic types.
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    Optimal Admission Control of Two Traffic Types at a Circuit- Switched Network Node
    (1991) Lambadaris, Ioannis E.; Narayan, P.; Viniotis, I.; ISR
    Two communication traffic streams with Poisson statistics arrive at a network node on separate routes. These streams are to be forwarded to their destinations via a common trunk. The two links leading to the common trunk have capacities C1 and C2 bandwidth units, respectively, while the capacity of the common trunk is C bandwidth units, where C < C1 + C2. Calls of either traffic type that are not admitted at the node are assumed to be discarded. An admitted call of either type will occupy, for an exponentially distributed random time, one bandwidth unit on its forwarding link as well as on the common trunk. Our objective is to determine a scheme for the optimal dynamic allocation of available bandwidth among the two traffic streams so as to minimize a weighted blocking cost. The problem is formulated as a Markov decision process. By using dynamic programming principles, the optimal admission policy is shown to be of the "bang-bang" type, characterized by appropriate "switching curves". The case of a general circuit-switched network, as well as numerical examples, are also presented.