Home // International Journal On Advances in Networks and Services, volume 7, numbers 1 and 2, 2014 // View article
Authors:
Ioannis Moscholios
Vassilios Vassilakis
Michael Logothetis
John Vardakas
Keywords: Poisson process, quasi-random, time-call congestion probability, elastic/adaptive traffic, reservation, Markov chains, retrials, recurrent formula
Abstract:
In this paper, we consider a single-link multirate loss system, which accommodates different service-classes with different traffic and peak-bandwidth requirements. Calls of each service-class arrive in the system according to a random (Poisson) or a quasi-random process, and have an exponentially distributed service time. Poisson or quasi-random arriving calls belong to service-classes of infinite or finite number of traffic sources, respectively. The service-classes are also distinguished, according to the behaviour of calls under service, in elastic and adaptive service-classes. Elastic calls can compress their bandwidth by simultaneously increasing their service time, while, adaptive calls do not affect their service time. A new call (either elastic or adaptive) is accepted in the system with its peak-bandwidth requirement, if there is available link bandwidth. If not, the call retries one or more times (single and multi-retry loss model, respectively) with a reduced bandwidth. If the available link bandwidth is lower than the call’s last bandwidth requirement, the call can still compress its last bandwidth requirement (down to a certain bandwidth), together with the bandwidth of all inservice calls. Call blocking occurs, if, after compression, the call’s bandwidth still exceeds the available link bandwidth. The system incorporates the Bandwidth Reservation (BR) policy, whereby we can achieve certain Quality of Service (QoS) for each service class, through a proper bandwidth allocation defined by the BR parameters. To calculate in an approximate but efficient way, time and call congestion probabilities, as well as link utilization, we propose recurrent formulas for the determination of the link occupancy distribution. The accuracy of the proposed formulas is verified by simulation, and is found to be very satisfactory. We show the consistency and the necessity of the proposed models.
Pages: 12 to 24
Copyright: Copyright (c) to authors, 2014. Used with permission.
Publication date: June 30, 2014
Published in: journal
ISSN: 1942-2644