The Experts below are selected from a list of 27150 Experts worldwide ranked by ideXlab platform
Krzysztof Pawlikowski - One of the best experts on this subject based on the ideXlab platform.
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Distributed steady-state simulation of Telecommunication Networks with self-similar teletraffic
Simulation Modelling Practice and Theory, 2005Co-Authors: Hae-duck J. Jeong, Donald C. Mcnickle, Jongsuk Ruth Lee, Krzysztof PawlikowskiAbstract:Abstract Recent measurement studies of teletraffic data in modern Telecommunication Networks have shown that self-similar processes may provide better models of teletraffic than Poisson processes. If this is not taken into account, it can lead to inaccurate conclusions about performance of Telecommunication Networks. We show how arrival processes with self-similar input influences the run-length of a distributed steady-state simulation of queueing systems in Telecommunication Networks. For this purpose, the simulation run-length of SSM/M/1/∞ queueing systems in the method based on the batch means, conducted for estimating steady-state mean waiting times is compared with the results obtained from simulations of M/M/1/∞ queueing systems when a single processor and multiple processors are used. We also investigate speedup conducted stochastic simulation of SSM/M/1/∞ queueing systems on multiple processors under a scenario of distributed stochastic simulation known as MRIP (Multiple Replications In Parallel) in a local area network (LAN) environment on Solaris operating system. We show that, assuming self-similar inter-event processes (i.e., SSM/M/1/∞ queueing systems), many more observations are required to obtain the final simulation results with a required precision, as the value of the Hurst parameter H increases, than when assuming Poisson models, exhibiting short-range dependence (i.e., M/M/1/∞ queueing systems) on a single processor and multiple processors. Our results show that the time for collecting many numbers of observations under the MRIP scenario is clearly reduced as traffic intensity and the value of the Hurst parameter increase, and as the engaged processor increases one to four. In particular, the value of H influences much more the speedup than traffic intensity and the engaged processor.
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do not trust all simulation studies of Telecommunication Networks
Lecture Notes in Computer Science, 2003Co-Authors: Krzysztof PawlikowskiAbstract:Since the birth of ARPANET and the first commercial applications of computer Networks, through explosion of popularity of the Internet and wireless communications, we have witnessed increasing dependence of our civilization on information services of Telecommunication Networks. Their efficiency and reliability have become critically important for the well-being and prosperity of societies as well as for their security. In this situation, the significance of performance evaluation studies of current and future Networks cannot be underestimated. Increasing complexity of Networks has resulted in their performance evaluation studies being predominantly conducted by means of stochastic discrete-event simulation. This paper is focused on the issue of credibility of the final results obtained from simulation studies of Telecommunication Networks. Having discussed the basic conditions of credibility, we will show that, unfortunately, one cannot trust the majority of simulation results published in technical literature. We conclude with general guidelines for resolving this credibility crisis.
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on credibility of simulation studies of Telecommunication Networks
IEEE Communications Magazine, 2002Co-Authors: Krzysztof Pawlikowski, Hae-duck J. Jeong, J S R LeeAbstract:In Telecommunication Networks, as in many other areas of science and engineering, the proliferation of computers as research tools has resulted in the adoption of computer simulation as the most commonly used paradigm of scientific investigations. This, together with a plethora of existing simulation languages and packages, has created a popular opinion that simulation is mainly an exercise in computer programming. In new computing environments, programming can be minimized, or even fully replaced, by the manipulation of icons (representing prebuilt programming objects containing basic functional blocks of simulated systems) on a computer monitor. One can say that we have witnessed another success of modern science and technology: the emergence of wonderful and powerful tools for exploring and predicting the behavior of such complex stochastic dynamic systems as Telecommunication Networks. But this enthusiasm is not shared by all researchers in this area. An opinion is spreading that one cannot rely on the majority of the published results on performance evaluation studies of Telecommunication Networks based on stochastic simulation, since they lack credibility. Indeed, the spread of this phenomenon is so wide that one can speak about a deep crisis of credibility. In this article this claim is supported by the results of a survey of over 2200 publications on Telecommunication Networks in proceedings of IEEE INFOCOM and such journals as IEEE Transactions on Communications, IEEE/ACM Transactions on Networking, and Performance Evaluation Journal. The discussion focuses on two important necessary conditions of a credible simulation study: use of appropriate pseudo-random generators of independent uniformly distributed numbers, and appropriate analysis of simulation output data. Having considered their perils and pitfalls, we formulate guidelines that, if observed, could help to ensure a basic level of credibility of simulation studies of Telecommunication Networks.
Ziyang Zhu - One of the best experts on this subject based on the ideXlab platform.
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resource allocation for network slicing in 5g Telecommunication Networks a survey of principles and models
IEEE Network, 2019Co-Authors: Dengyin Zhang, Ramachandran Venkatesan, Zijun Gong, Fei Ding, Fan Jiang, Ziyang ZhuAbstract:With the rapid and sustained growth of network demands, 5G Telecommunication Networks are expected to provide flexible, scalable, and resilient communication and network services, not only for traditional network operators, but also for vertical industries, OTT, and third parties to satisfy their different requirements. Network slicing is a promising technology to establish customized end-to-end logic Networks comprising dedicated and shared resources. By leveraging SDN and NFV, network slices associated with resources can be tailored to satisfy diverse QoS and SLA. Resource allocation of network slicing plays a pivotal role in load balancing, resource utilization, and networking performance. In this article, we focus on the principles and models of resource allocation algorithms in 5G network slicing. We first introduce the basic ideas of the SDN and NFV with their roles in network slicing. The MO architecture of network slicing is also studied, which provides a fundamental framework of resource allocation algorithms. Then, resource types with corresponding isolation levels in RAN slicing and CN slicing are analyzed, respectively. Furthermore, we categorize the mathematical models of resource allocation algorithms based on their objectives and elaborate them with typical examples. Finally, open research issues are identified with potential solutions.
Volker Schmidt - One of the best experts on this subject based on the ideXlab platform.
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Joint distributions for total lengths of shortest-path trees in Telecommunication Networks
annals of telecommunications - annales des télécommunications, 2015Co-Authors: David Neuhäuser, Christian Hirsch, Catherine Gloaguen, Volker SchmidtAbstract:Shortest-path trees play an important role in the field of optimising fixed-access Telecommunication Networks with respect to costs and capacities. Distributional properties of the corresponding two half-trees originating from the root of such a tree are of special interest for engineers. In the present paper, we derive parametric approximation formulas for the marginal density functions of the total lengths of both half-trees. Besides, a parametric copula is used in order to combine the marginal distributions of these functionals to a bivariate joint distribution as, naturally, the total lengths of the half-trees are not independent random variables. Asymptotic results for infinitely sparse and infinitely dense Networks are discussed as well.
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a parametric copula approach for modelling shortest path trees in Telecommunication Networks
Analytical and Stochastic Modeling Techniques and Applications, 2013Co-Authors: David Neuhäuser, Christian Hirsch, Catherine Gloaguen, Volker SchmidtAbstract:We extend the Stochastic Subscriber Line Model by the introduction of shortest-path trees which are obtained by splitting up the segment system of the typical serving zone at its crossings and endings. Due to reasons in the complex field of cost and capacity estimation in Telecommunication Networks, it is desirable to gain knowledge about distributional properties of the branches of these trees. The present paper shows how to obtain parametric approximation formulas for the univariate density functions of the lengths of the two main branches in shortest-path trees. Besides, we derive a joint bivariate distribution for the lengths of these branches by means of copula functions, i.e., we give a parametric composition formula of the marginals. These approximative parametric representation formulas can be used in order to prevent time consuming computer experiments.
A.p. Redfern - One of the best experts on this subject based on the ideXlab platform.
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MASCOTS - Fast Parallel Simulation of SS7 Telecommunication Networks
1993Co-Authors: Nasser Kalantery, Stephen Winter, Derek R. Wilson, A.p. RedfernAbstract:Simulation of large Telecommunication Networks consumes a huge amount of time on sequential machines. Execution of a parallel version of the simulator on multiprocessor computers presents an opportunity to achieve faster execution. However, correct temporal sequencing of events in a parallel environment, presents new problems which do not exist in a sequential single processor implementation. Two principle approaches, the conservative and the optimistic approaches, have been developed to alleviate these problems. The authors use a variation of the conservative deadlock avoidance algorithm to build a parallel simulation of the SS7 Telecommunication network. The main advantage of this algorithm is the relative simplicity of its implementation as compared to the implementation of optimistic methods. The paper presents empirical data on the performance of the simulator and demonstrates how by exploiting link reliability features of the Telecommunication network, a significantly better and more stable speedup of execution is achieved.
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PDP - Exploiting lookahead in parallel simulation of SS7 Telecommunication Networks
1993 Euromicro Workshop on Parallel and Distributed Processing, 1Co-Authors: Nasser Kalantery, Stephen Winter, Derek R. Wilson, A.p. RedfernAbstract:This paper describes techniques used to optimise the performance of parallel simulation of SS7 Telecommunication Networks. A basic parallel simulation model of an SS7 network and the conservative implementation of the model are discussed and experimental results on the performance of the simulator are examined. A technique for achieving further optimisation is proposed. >
Daniel A Keim - One of the best experts on this subject based on the ideXlab platform.
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visualizing large scale Telecommunication Networks and services
IEEE Visualization, 1999Co-Authors: Eleftherios Koutsofios, Stephen C North, R Truscott, Daniel A KeimAbstract:Visual exploration of massive datasets arising from Telecommunication Networks and services is a challenge. This paper describes SWIFT-3D, an integrated data visualization and exploration system created at AT&T Labs for large scale network analysis. SWIFT-3D integrates a collection of interactive tools that includes pixel-oriented 2D maps, interactive 3D maps, statistical displays, network topology diagrams and an interactive drill-down query interface. Example applications are described, demonstrating a successful application to analyze unexpected network events (high volumes of unanswered calls), and comparison of usage of an Internet service with voice network traffic and local access coverage.
