Browsing by Author "Karatzaglu, Minas A."

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    Decomposition of a Multiple Access Network into a Number of Interconnected Subnetworks.
    (1989) Karatzaglu, Minas A.; Ephremides, Anthony; ISR
    A random access system with a finite number of buffered terminals is considered. The problem of how to decompose this system into a number of interconnected subsystems in order to maximize its throughput is studied. Two different interconnection topologies are considered, a directional ring topology and a fully connected network of subsystems. For each of these two topologies the problem of maximizing the throughput is reduced to a simple maximization problem. We apply the attained results to a slotted ALOHA and a CSMA/CD system. For the former a significant improvement in the throughput performance is reported, while simulation analysis shows an expected deterioration in the delay performance, for low intensity traffic.
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    Ergodicity of M-dimensional Random Walks and Random Access Systems.
    (1989) Karatzaglu, Minas A.; Ephremides, Anthony; ISR
    We apply a set of recent results by Malysev and Mensikov, concerning necessary or sufficient conditions for ergodicity of constrained M-dimensional random walks to the problem of stability of M coupled queueing systems that describe a system of M buffered terminals accessing a common channel by means of the slotted ALOHA protocol. We obtain a necessary and sufficient condition for the stability of such a system. Although the condition does not yield a descriptive characterization of the stability region, it allows a reduction of the stability problem of a M-user system to the determination of the steady state distribution of a (M-1)user system. The plausibility of a recent conjecture concerning the stability of this system is also discussed.