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Performance Evaluation of the Threshold Call Admission Policy in Multi-rate Loss Systems

Moscholios Ioannis D., Chousainov Iskanter-Alexandros, Panagoulias Panagiotis I., Sarigiannidis Panagiotis G., Logothetis Michael D.

Journal of Telecommunications and Information Technology

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2020

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nr 2

51--60

EN

In this paper we consider a link, characterized by speciﬁc capacity, that services multi-rate random or quasirandom traﬃc. Random traﬃc is generated by an inﬁnite number of traﬃc sources, while quasi-random traﬃc is generated by a ﬁnite population of traﬃc sources. The link is modeled as a multi-rate loss system. Handover and new calls are distinguished. New calls compete for the available bandwidth under a threshold call admission policy. In that policy, a new call of a particular service-class is not allowed to enter the system if the in-service handover and new calls of the same service-class plus the new call, exceed a predeﬁned threshold (which can be diﬀerent for each service-class). On the other hand, handover calls compete for the available bandwidth based on the complete sharing policy. We show that the steady state probabilities in the proposed models have a product form solution (PFS). The PFS leads to a convolution algorithm for accurate calculation of congestion probabilities and link utilization.

2

Call-level Analysis of a Two-Link Multirate Loss Model based on a Convolution Algorithm

Sagkriotis S. G., Pantelis S. K., Moscholios I. D., Vassilakis V. G.

Journal of Telecommunications and Information Technology

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2018

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nr 1

3--10

EN

We consider a two-link system that accommodates Poisson arriving calls from different service-classes and propose a multirate teletraffic loss model for its analysis. Each link has two thresholds, which refer to the number of in-service calls in the link. The lowest threshold, named support threshold, defines up to which point the link can support calls offloaded from the other link. The highest threshold, named offloading threshold, defines the point where the link starts offloading calls to the other link. The adopted bandwidth sharing policy is the complete sharing policy, in which a call can be accepted in a link if there exist enough available bandwidth units. The model does not have a product form solution for the steady state probabilities. However, we propose approximate formulas, based on a convolution algorithm, for the calculation of call blocking probabilities. The accuracy of the formulas is verified through simulation and found to be quite satisfactory.

3

Algorithm for queueing networks with multi-rate traffic

Iversen V. B., King-Tim K.

Advances in Electronics and Telecommunications

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2011

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Vol. 2, no. 3

3--7

EN

In this paper we present a new algorithm for evaluating queueing networks with multi-rate traffic. The detailed state space of a node is evaluated by explicit formulæ. We consider reversible nodes with multi-rate traffic and find the state probabilities by taking advantage of local balance. Theory of queueing networks in general, presumes that we have product form between the nodes. Otherwise, we have the state space explosion. Even so, the detailed state space of each node may become very large because there is no product form between chains inside a node. A prerequisite for product form is reversibility which implies that the arrival process and departure process are identical processes, for example state-dependent Poisson processes. This property is equivalent to reversibility. Due to product form, an open network with multi-rate traffic is easy to evaluate by convolution algorithms because the nodes behave as independent nodes. For closed queueing networks with multiple servers in every node and multi-rate services we may apply multidimensional convolution algorithm to aggregate the nodes so that we end up with two nodes, the aggregated node and a single node, for which we can calculate the detailed performance measures.