Browsing by Subject "Queuing analysis"

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Open Access
Numerical methods for the transient analysis of multi-regime Markov fluid queues
(2019-01) Gürsoy, Ömer
Markov fluid queue models have served as one of the main tools for the performance analysis of computer and communication systems and networks. These models have also been used in other disciplines such as insurance risk, finance, inventory control, etc. This thesis focuses on the time dependent (transient) analysis of Markov uid queue models. In particular, a numerical method is proposed to obtain both the transient and first passage time distributions of a Multi-Regime Markov Fluid Queue (MRMFQ). The proposed method is based on obtaining the steady-state solution of an auxiliary MRMFQ that is to be constructed from the original MRMFQ which then leads to the related transient measures of interest. First, in order to model the deterministic time horizon, the Erlangization method is used. Then, as an alternative to Erlangization, ME-fication technique which efficiently replaces the Erlang distribution with a Concentrated Matrix Exponential (CME), is used. As an application of the proposed method, an M/M/S+G queue with generally distributed impatience times is modeled by using MRMFQs and our transient analysis method is subsequently applied to obtain the time dependent distributions. Numerical examples are given to show the effectiveness of the proposed transient analysis method while employing ME-fication.
Open Access
On the Queuing Model of the energy-delay tradeoff in wireless links with power control and link adaptation
(IEEE, 2019-05) Gamgam, Ege Orkun; Tunç, Çağlar; Akar, Nail
A transmission profile refers to a transmission power and a modulation and coding scheme to be used for packet transmissions over a wireless link. The goal of this paper is to develop transmission profile selection policies so as to minimize the average power consumption on a wireless link while satisfying a certain delay constraint given in terms of a delay violation probability. Toward the assessment of profile selection policies, a multi-regime Markov fluid queue model is proposed to obtain the average power consumption and the queue waiting time distribution which allows one to analyze the energy-delay tradeoff in queuing systems for which the packet transmission duration is allowed to depend on the delay experienced by the packet until the beginning of service. Numerical examples are presented with transmission profiles obtained from realistic LTE simulations. Several transmission profile selection policies are proposed and subsequently compared using the analytical model.