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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1994 - 19964

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Author: search.filters.author.Kim, Young B.Subject: search.filters.subject.Communications Systems

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    Stochastic Comparison Results for Non-Blocking Switches with Output Queueing
    (1996) Kim, Young B.; Makowski, Armand M.; ISR; CSHCN
    We propose a systematic approach to quantify the impact of nonuniform traffic on the performance of non-blocking switches with output queueing. We do so in the context of a simple queueing model where cells arrive to input ports according to independent Bernoulli processes, and are switched to an output port under a random routing mechanism. We give conditions on pairs of input rate vectors and switching matrices which ensure various stochastic comparisons for performance measures of interest. These conditions are formulated in terms of the majorization ordering while the comparison results are expressed in the strong and convex increasing orderings.
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    Simple Optimization Problems via Majorization Ordering
    (1996) Kim, Young B.; Makowski, Armand M.; ISR
    We introduce and explicitly solve a novel class of optimization problems which are motivated by load assignment issues in crossbar switches with output queueing. The optimization criterion is given in the majorization ordering sense. The solution to these problems indirectly provide solutions to a large class of convex optimization problems under a linear constraint.
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    Large Size Asymptotics for Crossbar Switches with Input Queueing
    (1995) Kim, Young B.; Makowski, Armand M.; ISR; CSHCN
    With the advent of high-speed networks, various switch architectures have been proposed to meet the increasingly stringent performance requirements being placed on the underlying switching systems. In general, the performance analysis of such a switch architecture is a difficult task mainly due to the fact that a switch consists of a large number of queues which interact with each other in a fairly complicated manner. In this paper, we analyze a crossbar switch with input queueing in terms of maximum throughput, and formalize the phenomenon that virtual queues formed by the head-of-line cells become decoupled as the switch size grows unboundedly large. We also establish various properties of the limiting queue size processes so obtained.
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    Cell Loss Probabilities in Input Queueing Crossbar Switches Via Light Traffic
    (1994) Kim, Young B.; Makowski, Armand M.; ISR; CSHCN
    Under most system assumptions, closed form solutions of performance measures for input queueing crossbar switches are not available. In this paper, we present expressions and bounds for the derivatives of cell loss probabilities with respect to the arrival rate evaluated at a zero arrival rate. These bounds are used to give an approximation by Taylor expansion, thereby providing an economical way to estimate cell loss probabilities in light traffic.