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1
Content available 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.
2
Content available Call Blocking Probabilities of Multirate Elastic and Adaptive Traffic under the Threshold and Bandwidth Reservation Policies
Moscholios I. D., Logothetis M. D., Boucouvalas A. C., Vassilakis V. G.
Journal of Telecommunications and Information Technology
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2016
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nr 1
44--52
EN
This paper proposes multirate teletraffic loss models of a link that accommodates different service-classes of elastic and adaptive calls. Calls follow a Poisson process, can tolerate bandwidth compression and have an exponentially distributed service time. When bandwidth compression occurs, the service time of new and in-service elastic calls increases. Adaptive calls do not alter their service time. All calls compete for the available link bandwidth under the combination of the Threshold (TH) and the Bandwidth Reservation (BR) policies. The TH policy can provide different QoS among service-classes by limiting the number of calls of a service-class up to a predefined threshold, which can be different for each service-class. The BR policy reserves part of the available link bandwidth to benefit calls of high bandwidth requirements. The analysis of the proposed models is based on approximate but recursive formulas, whereby authors determine call blocking probabilities and link utilization. The accuracy of the proposed formulas is verified through simulation and found to be very satisfactory.
3
Content available remote Congestion probabilities in erlang-engset multirate loss models under the multiple fractional channel reservation policy
Moscholios I. D.
Image Processing & Communications
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2016
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Vol. 21, no. 1
33--44
EN
A communication link that accommodates different service-classes whose calls have different bandwidth requirements and compete for the available bandwidth under the Multiple Fractional Channel Reservation (MFCR) policy is considered. The MFCR policy allows the reservation of real number of channel In order to fawor high Speer calls. Two call arrival processes are studied: i) the Poisson (random) process and ii) the quasi-random process. In the first case, calls come from an infinite number of sources while in the second case calls are generated by a finite number of sources. To determine call blocking probabilities for Poisson arriving calls, recursive formulas are proposed based on reverse transition rates. To determine time and call congestion probabilities for quasi-random arriving calls,recursive formulas are proven based on the fact that the steady state probabilities cannot be described by a product form solution. The accuracy of the new formulas is verified through simulation.
4
Content available remote Calculating distributed denial of service attack probability in bloom-filter based information-centric networks
Vassilakis V. G., Wang L., Moscholios I. D., Logothetis M. D.
Image Processing & Communications
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2016
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Vol. 21, no. 1
7--22
EN
Information-Centric Networking (ICN) is an emerging networking technology that has been designed to directly operate on named content/information objects, rather than relying on the knowledge of the content location. According to the ICN principles, a user requests the information object by its name or some other form of object identifier. After that, the ICN system is responsible for finding the particular object and send In git back to theuser. Despite a large number of works on ICN in recent years, ICN systems still face security challenges. This is especially true when considering different types of alternative networks, such as the wireless community networks (WCNs). In this work, we explore the applicability of ICN principles in the challenging and unpredictable environments of WCNs. We consider stateless contentdisseminationusingBloomfilters(BFs) and analyze two BF based approaches: the traditional single-stage BF and its generalization, the multi-stageBF. We fokus on the security aspects of BF based approaches and in particular on distributed denial of service (DDoS) attacks. Finally, we investigate the attaca probabilisty for various system and net work parameters, such as the number of hash functions, the BFmaximum fill factor, and the number of hops toward the victim node.
5
Content available QoS Equalization in a W-CDMA Cell Supporting Calls of Innite or Finite Sources with Interference Cancelation
Moscholios I. D., Kallos G. A., Katsiva M. A., Vassilakis V. G., Logothetis M. D.
Journal of Telecommunications and Information Technology
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2014
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nr 3
63--70
EN
In this paper, a multirate loss model for the calculation of time and call congestion probabilities in a Wideband Code Division Multiple Access (W-CDMA) cell is considered. It utilizes the Bandwidth Reservation (BR) policy and supports calls generated by an infinite or finite number of users. The BR policy achieves QoS equalization by equalizing congestion probabilities among calls of dierent service-classes. In the proposed models a multiple access interference is considered, and the notion of local blocking, user's activity and interference cancelation. Although the analysis of the proposed models reveals that the steady state probabilities do not have a product form solution, the authors show that the calculation of time and call congestion probabilities can be based on approximate but recursive formulas, whose accuracy is verified through simulation and found to be quite satisfactory.
6
Content available remote Derivatives of Blocking Probabilities in Multirate Access Tree Networks
Moscholios I. D., Vardakas J. S., Logothetis M. D., Boucouvalas A. C.
Advances in Electronics and Telecommunications
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2013
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Vol. 3, no. 5
38--48
EN
We consider a multirate access tree network accommodating service-classes of Poisson traffic, and focus on the determination of derivatives of Call Blocking Probabilities (CBP) with respect to offered traffic-load of any service-class. Based on the derivatives, we further show how we can successfully approximate CBP for small variations of offered traffic-load.
7
Content available remote Retry Loss Models Supporting Elastic Traffic
Moscholios I. D., Vasilakis V. G., Vardakas J. S., Logothetis M. D.
Advances in Electronics and Telecommunications
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2011
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Vol. 2, no. 3
8--13
EN
We consider a single-link loss system of fixed capacity, which accommodates K service-classes of Poisson traffic with elastic bandwidth-per-call requirements. When a new call cannot be accepted in the system with its peak-bandwidth requirement, it can retry one or more times (single and multi-retry loss model, respectively) to be connected in the system with reduced bandwidth requirement and increased service time, exponentially distributed. Furthermore, if its last bandwidth requirement is still higher than the available link bandwidth, it can be accepted in the system by compressing not only the bandwidth of all inservice calls (of all service-classes) but also its last bandwidth requirement. The proposed model does not have a product form solution and therefore we propose an approximate recursive formula for the calculation of the link occupancy distribution and consequently call blocking probabilities. The accuracy of the proposed formula is verified by simulation and is found to be quite satisfactory.
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