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GMSim: A generalized semiMarkov simulation environment
, 1998
"... A discreteevent simulation environment, called GMSim, based on the generalized semiMarkov process (GSMP) framework is described. The tool is completely generic and extendible by Tcl script programming. Application specific components are developed in an objectedoriented setting by C++ programming ..."
Abstract

Cited by 5 (5 self)
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A discreteevent simulation environment, called GMSim, based on the generalized semiMarkov process (GSMP) framework is described. The tool is completely generic and extendible by Tcl script programming. Application specific components are developed in an objectedoriented setting by C++ programming in combination with M4 macro processing. Components are conveniently integrated by runtime linking. The strong links to the underlying mathematical GSMP description is favorable in two respects. First, qualitative results from a body of theory is readily available. Next, the structured view leads to an efficient implementation.
On Latency Estimation in WormholeSwitched Networks
"... This paper compares unbuffered wormholeswitched networks and buffered packetswitched networks with respect to estimation of expected packet latency. Simulation experiments show that the variance of the natural samplemean estimator is significantly larger in the wormholeswitched case. An inc ..."
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Cited by 3 (3 self)
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This paper compares unbuffered wormholeswitched networks and buffered packetswitched networks with respect to estimation of expected packet latency. Simulation experiments show that the variance of the natural samplemean estimator is significantly larger in the wormholeswitched case. An increased estimator variance is an evidence of a harder estimation problem. In particular, it leads to larger confidence intervals. The increased variance is attributed to the inline blocking property of wormholeswitched networks. This property results from lack of smoothing buffers at the switching points. The overall effect is to increase both the variance of individual latency recordings and also the amount of serial correlation in the sequence of latency samples. The performance of two frequently used variance estimators is assessed in this paper. Estimating variance by assuming independent samples fails for unbuffered networks. A batchedmeans method do work provided the ba...
Variance Reduction for Mean Latency in WormholeSwitched Networks
, 1998
"... This paper discusses variance reduction for estimation of mean packet latency in wormholeswitched networks. Our interest is motivated by the fact that the variance of the natural samplemean estimator is much larger for unbuffered systems than for traditional buffered packetswitched networks. ..."
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Cited by 1 (1 self)
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This paper discusses variance reduction for estimation of mean packet latency in wormholeswitched networks. Our interest is motivated by the fact that the variance of the natural samplemean estimator is much larger for unbuffered systems than for traditional buffered packetswitched networks. One way to achieve variance reduction is to modify the natural estimator in terms of a control variate. The effect of two such strategies are studied in this paper. Simulation experiments are used to quantify the effect. The first approach uses an internal control variate built from latency intersample times. The other strategy is to employ a M /M /s queuing model which is simulated in parallel. This model represents an approximation of the true network, hence subsequent queuing times can be used to construct an external control variate. Our conclusion is that a variance reduction of about 20% can be obtained. On the balance we recommend the method using an internal control var...
UNIVERSITY OF OSLO Department of Informatics
, 1998
"... generalized semiMarkov simulation environment ..."
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Methods for Performance Evaluation of WormholeSwitched Networks
, 1998
"... this document. Hence, the same stylistic conventions are used throughout. ..."
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this document. Hence, the same stylistic conventions are used throughout.