348 research outputs found
Call blocking probabilities for Poisson traffic under the Multiple Fractional Channel Reservation policy
In this paper, we study the performance of the Multiple Fractional Channel Reservation (MFCR) policy, which is a bandwidth reservation policy that allows the reservation of real (not integer) number of channels in order to favor calls of high channel (bandwidth) requirements. We consider a link of fixed capacity that accommodates Poisson arriving calls of different service-classes with different bandwidth-per-call requirements. Calls compete for the available bandwidth under the MFCR policy. To determine call blocking probabilities, we propose approximate but recursive formulas based on the notion of reserve transition rates. The accuracy of the proposed method is verified through simulation
Modelling Pascal traffic in overflow systems
In this paper, impact of changes in parameters of offeredtraffic on the accuracy of determining the parameters of overflowtraffic in hierarchy systemswithmulti-service traffic was presented. Pascal typetrafficstreamswereoffered to the consideredsystems. The study investigated the impact of changes in the number of sources, intensity of trafficoffered by individualclasses, as well as changes in the trafficoffered by single free source. The presentedresultsarebased on determined relative errors of the values of overflowtrafficobtained in simulations and on the basis of calculations
Simplified methods for next generation IP access networks planning
The scope of this paper is to derive a set of simple formulas providing a traffic aggregation in important points of an Internet access networks. The paper shows that the resources associated to the access network depend on user type-, technology and service parameter. Existing calculation methodologies applies on individual approximations whereas this proposal exposes the combined application of these individual and wellknown approximations providing a scheme of generic dimensioning formulas. The dimensioning formulas for a generic applications are derived for the three main levels: connection, session and burst level, and the traffic aggregation is considered through three different and combined variables describing users, accesses and services forming a cube with three axes. The adaptation of corresponding parameters following the different axes allows the calculation of complete access network traffic scenarios, grouped by the so called CASUAL concept: Cube of Accesses / Services / Users. A set of CASUAL based tools allows an estimation of the aggregated traffic in different access points as multiplexers, IP point of presence or edge routers
Journal of Telecommunications and Information Technology, 2018, nr 1
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
A Price Based Spectrum Sharing Scheme in Wireless Cellular Networks
Radio frequency spectrum scarcity has become a high priority research area over the past few years. The huge increase of network subscribers with multimedia applications coupled with underutilization of radio frequency spectrum motivates the search for other measures to address the scarcity of radio frequency spectrum. This work investigates on a price based spectrum sharing scheme for connection-oriented traffic in wireless cellular networks as a solution to address the scarcity of radio frequency spectrum. Dynamic pricing approach is applied with traffic overflows into neighbor networks. Performance evaluations of the scheme at steady state using MATLAB simulations reveal significant gains to the quality of service. Application of the scheme to highly loaded network traffic improves both network revenue and traffic channel utilizations. Keywords?Pricing, spectrum sharing, traffic overflows, Quality of service, channel utilizations, Wireless cellular networks
Monotonicity and error bounds for networks of Erlang loss queues
Networks of Erlang loss queues naturally arise when modelling finite communication systems without delays, among which, most notably\ud
(i) classical circuit switch telephone networks (loss networks) and\ud
(ii) present-day wireless mobile networks.\ud
\ud
Performance measures of interest such as loss probabilities or throughputs can be obtained from the steady state distribution. However, while this steady state distribution has a closed product form expression in the first case (loss networks), it has not in the second case due to blocked (and lost) handovers. Product form approximations are therefore suggested. These approximations are obtained by a combined modification of both the state space (by a hyper cubic expansion) and the transition rates (by extra redial rates). It will be shown that these product form approximations lead to\ud
\ud
- secure upper bounds for loss probabilities and\ud
- analytic error bounds for the accuracy of the approximation for various performance measures.\ud
\ud
The proofs of these results rely upon both monotonicity results and an analytic error bound method as based on Markov reward theory. This combination and its technicalities are of interest by themselves. The technical conditions are worked out and verified for two specific applications:\ud
\ud
- pure loss networks as under (i)\ud
- GSM-networks with fixed channel allocation as under (ii).\ud
\ud
The results are of practical interest for computational simplifications and, particularly, to guarantee blocking probabilities not to exceed a given threshold such as for network dimensioning.\u
Monotonicity and error bounds for networks of Erlang loss queues
Networks of Erlang loss queues naturally arise when modelling finite communication systems without delays, among which, most notably are (i) classical circuit switch telephone networks (loss networks) and (ii) present-day wireless mobile networks. Performance measures of interest such as loss probabilities or throughputs can be obtained from the steady state distribution. However, while this steady state distribution has a closed product form expression in the first case (loss networks), it does not have one in the second case due to blocked (and lost) handovers. Product form approximations are therefore suggested. These approximations are obtained by a combined modification of both the state space (by a hypercubic expansion) and the transition rates (by extra redial rates). It will be shown that these product form approximations lead to (1) upper bounds for loss probabilities and \ud
(2) analytic error bounds for the accuracy of the approximation for various performance measures.\ud
The proofs of these results rely upon both monotonicity results and an analytic error bound method as based on Markov reward theory. This combination and its technicalities are of interest by themselves. The technical conditions are worked out and verified for two specific applications:\ud
(1)âą pure loss networks as under (2)âą GSM networks with fixed channel allocation as under.\ud
The results are of practical interest for computational simplifications and, particularly, to guarantee that blocking probabilities do not exceed a given threshold such as for network dimensioning
Hierarchical Multiobjective Routing in MPLS Networks with Two Service Classes â A Meta-Heuristic Solution, Journal of Telecommunications and Information Technology, 2009, nr 3
The paper begins by reviewing a two-level hierarchical multicriteria routing model for MPLS networks with two service classes (QoS and BE services) and alternative routing, as well as the foundations of a heuristic resolution approach, previously proposed by the authors. Afterwards a new approach, of meta-heuristic nature, based on the introduction of simulated annealing and tabu search techniques, in the structure of the dedicated heuristic, is described. The application of the developed procedures to a benchmarking case study will show that, in certain initial conditions, this approach provides improvements in the final results especially in more âdifficultâ situations detected through sensitivity analysis
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