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Mathematical Problems in Engineering
Volume 2013 (2013), Article ID 241241, 9 pages
Research Article

Control of Traffic Intensity in Hyperexponential and Mixed Erlang Queueing Systems with a Method Based on SPRT

1Department of Statistics, Amasya University, 05000 Amasya, Turkey
2Department of Statistics, Ondokuz Mayıs University, 55139 Samsun, Turkey

Received 6 December 2012; Revised 30 May 2013; Accepted 10 June 2013

Academic Editor: Wuquan Li

Copyright © 2013 Müjgan Zobu and Vedat Sağlam. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The control of traffic intensity is one of the important problems in the study of queueing systems. Rao et al. (1984) developed a method to detect changes in the traffic intensity in queueing systems of the and types based on the Sequential Probability Ratio Test (SPRT). In this paper, SPRT is theoretically investigated for two different phase-type queueing systems which consist of hyperexponential and mixed Erlang. Also, for testing against , Operating Characteristic (OC) and Average Sample Number (ASN) functions are obtained with numerical methods using multipoint derivative equations according to different situations of and type errors. Afterward, numerical illustrations for each model are provided with Matlab programming.