Publications (20)0 Total impact
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Article: Adaptive Call Admission Control for QoS/Revenue Optimization in CDMA Cellular Networks.
Wireless Networks. 01/2004; 10:457-472. -
Article: Mobile Networks and Applications 8, 209--221, 2003
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ABSTRACT: In this paper, we introduce a unified approach for the adaptive control of 3G mobile networks in order to improve both quality of service (QoS) for mobile subscribers and to increase revenue for service providers. The introduced approach constantly monitors QoS measures as packet loss probability and the current number of active mobile users during operation of the network. Based on the values of the QoS measures just observed, the system parameters of the admission controller and packet scheduler are controlled by the adaptive performance management entity. Considering UMTS, we present performance curves showing that handover failure probability is improved by more than one order of magnitude. Moreover, the packet loss probability can be effectively regulated to a predefined level and provider revenue is significantly increased for all pricing policies.05/2003; -
Article: Modeling IP Traffic Using the Batch Markovian Arrival Process
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ABSTRACT: In this paper, we show how to utilize the expectation-maximization (EM) algorithm for efficient and numerical stable parameter estimation of the batch Markovian an'ival process (BMAP). In fact, effective computational formulas for the E-step of the EM algorithm are presented, which utilize the well-known randomization technique and a stable calculation of Poisson jump probabilities.05/2003; -
Article: Modeling IP traffic using the batch Markovian arrival process.
Perform. Eval. 01/2003; 54:149-173. -
Article: A Unified Approach for Improving QoS and Provider Revenue in 3G Mobile Networks.
MONET. 01/2003; 8:209-221. -
Article: In Proc. 3
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ABSTRACT: In this paper, we propose extensions to UML state diagrams and activity diagrams in order to allow the association of events with exponentially distributed and deterministic delays. We present an efficient algorithm for the state space generation out of these UML diagrams that allows a quantitative analysis by means of an underlying stochastic process. We identify a particular stochastic process, the generalized semi-Markov process (GSMP), as the appropriate vehicle on which quantitative analysis is performed. As innovative feature the algorithm removes vanishing states, i.e. states with no timed events active, and considers branching probabilities within activity diagrams. Furthermore, we introduce a performance evaluation framework that allows a system designer to predict performance measures at several steps in the design process. The applicability of our approach for practical performance and dependability projects is demonstrated by an UML specification of the General Packet Radio Service, a packet switched extension in GSM wireless networks.09/2002; -
Article: Performance Analysis of Time-enhanced UML Diagrams Based on Stochastic Processes
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ABSTRACT: In this paper, we propose extensions to UML state diagrams and activity diagrams in order to allow the association of events with exponentially distributed and deterministic delays. We present an efficient algorithm for the state space generation out of these UML diagrams that allows a quantitative analysis by means of an underlying stochastic process. We identify a particular stochastic process, the generalized semi-Markov process (GSMP), as the appropriate vehicle on which quantitative analysis is performed. As innovative feature the algorithm removes vanishing states, i.e. states with no timed events active, and considers branching probabilities within activity diagrams. Furthermore, we introduce a performance evaluation framework that allows a system designer to predict performance measures at several steps in the design process. The applicability of our approach for practical performance and dependability projects is demonstrated by an UML specification of the General Packet Radio Service, a packet switched extension in GSM wireless networks.05/2002; -
Article: Adaptive Performance Management for Universal Mobile Telecommunications System Networks
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ABSTRACT: In this paper, we introduce a f#BQ#q6( ff the adaptive controlof universal mobile telecommunications system (UMTS) networks in order to improve bandwidth utilizationof the radio channels. The key contributionof the paper constitutes the introductionof aperfQ6(-jQ management infgement6 basefs dynamically adjusting the packet scheduler and admission controller. Thus, the adaptive controlfntrol6# closes the loop between network operation and network control. Furthermore, the adaptive controlfntrol6# can e#ectively deal with the di#erent time scalesof packet scheduling and admission control. Moreover, we present a tra#c modelfd non-real-time UMTS tra#c based on measured trace data. The analysis and scaling processof the measured trace data with respect to di#erent UMTS bandwidth classes constitutes the basic conceptof this tra#c characterization. Using this tra#c model and simulation on the IP level, the gainof employing the adaptive controlfntrol6# is illustrated byperfjj6(#P curvesfr various qualityof service measures. # 2002 Elsevier Science B.V. All rights reserved.03/2002; -
Conference Proceeding: Performance analysis of time-enhanced UML diagrams based on stochastic processes.
01/2002 -
Chapter: Traffic Modeling of IP Networks Using the Batch Markovian Arrival Process
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ABSTRACT: In this paper, we identify the batch Markovian arrival process (BMAP) as an analytically tractable model of choice for aggregated traffic modeling of IP networks. The key idea of this aggregated traffic model lies in customizing the batch Markovian arrival process such that the different lengths of IP packets are represented by rewards (i.e., batch sizes of arrivals) of the BMAP. The utilization of the BMAP is encouraged by the observation that IP packet lengths follow to a large extent a discrete distribution. A comparative study with the MMPP and the Poisson process illustrates the effectiveness of the customized BMAP for IP traffic modeling by visual inspection of sample paths over four different time-scales, by presenting important statistical properties, and by analysis of traffic burstiness using R/S statistics. Additionally, we show that the BMAP model outperforms MMPP and Poisson traffic models by comparison of queuing performance.12/2001: pages 129-182; -
Article: Traffic Modeling of IP Networks Using the Batch Markovian Arrival Process
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ABSTRACT: In this paper, we identify the batch Markovian arrival process (BMAP) as analytically tractable model of choice for aggregated traffic modeling of IP networks. The key idea of this aggregated traffic model lies in customizing the batch Markovian arrival process such that the different lengths of IP packets are represented by rewards (i.e., batch sizes of arrivals) of the BMAP. The utilization of the BMAP is encouraged by the observation that IP packet lengths follow to a large extend a discrete distribution. A comparative study with the MMPP and the Poisson process illustrates the effectiveness of the customized BMAP for IP traffic modeling by visual inspection of sample paths over four different timescales, by presenting important statistical properties, and by analysis of traffic burstiness using R/S statistics. Additionally, we show that the BMAP model outperforms MMPP and Poisson traffic models by comparison of queuing performance.12/2001; -
Article: In Proc. 2
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ABSTRACT: This paper describes the software package DSPNexpress 2000, a tool for the quantitative evaluation of systems specified in stochastic Petri nets, the Unified Modeling Language (UML), or other specification languages for discrete-event systems. Linking the DSPNexpress software to commercial UML design packages allows the effective computation of performance measures like throughput and delay for UML system specifications. The unique feature of DSPNexpress constitute numerical solvers for transient and steady-state analysis of generalized-semi Markov processes with exponential and deterministic events, which may be concurrently active. The applicability of the DSPNexpress software for practical performance and dependability projects is demonstrated by an UML specification of an alternating bit protocol. The computational effort required by DSPNexpress for transient and steady-state analysis is plotted for varying model size. Furthermore, a performance curve for a measure of interest is presented.10/2001; -
Article: Adaptive Performance Management for UMTS Networks
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ABSTRACT: In this paper, we introduce a framework for the adaptive control of UMTS networks in order to improve bandwidth utilization of the radio channels. The key contribution of the paper constitutes the introduction of a performance management information base for dynamically adjusting the packet scheduler and admission controller. Thus, the adaptive control framework closes the loop between network operation and network control. Furthermore, the adaptive control framework can effectively deal with the different time scales of packet scheduling and admission control. Moreover, we present a traffic model for non real-time UMTS traffic based on measured trace data. The analysis and scaling process of the measured trace data with respect to different UMTS bandwidth classes constitutes the basic concept of this traffic characterization. Using this traffic model and simulation on the IP-level, the gain of employing the adaptive control framework is illustrated by performance curves for various QoS measures. Keywords: 3G Wireless Systems, Performance Management, QoS Provisioning, Discrete-event Simulation. -2110/2001; -
Article: Traffic Modeling and Characterization for UMTS Networks
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ABSTRACT: In this paper, we present a synthetic traffic model for the Universal Mobile Telecommunication Systems (UMTS) based on measured trace data. The analysis and scaling process of the measured trace data with respect to different bandwidth classes constitutes the basic concept of the UMTS traffic characterization. Furthermore, we introduce an aggregated traffic model for UMTS networks that is analytically tractable. The key idea of this aggregated traffic model lies in customizing the batch Markovian arrival process (BMAP) such that different packet sizes of IP packets are represented by rewards (i.e., batch sizes of arrivals) of the BMAP. The effectiveness of the customized BMAP for modeling UMTS traffic is illustrated using the synthetic traffic model previously presented.09/2001; -
Article: Numerical Robust Parameter Estimation for the Batch Markovian Arrival Process Using Randomization
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ABSTRACT: In this paper, we show how to utilize the expectationmaximization (EM) algorithm for efficient and numerical stable parameter estimation of the batch Markovian arrival process (BMAP). In fact, effective computational formulas for the E-step of the EM algorithm are presented, which utilize the well-known randomization technique and a stable calculation of Poisson jump probabilities. Using measured traffic data, we show that the analytically tractable BMAP closely captures the statistics of the measured traffic. The accuracy of the parameter estimation for BMAPs is illustrated by visual inspection of sample paths over four different time scales, by presenting important statistical properties, by formal analysis of traffic burstiness using R/S statistics, as well as by investigations of queuing behavior. Index terms-- Network modeling, network measurements, workload characterization, analytical/numerical models of aggregated IP traffic. I.09/2001; -
Article: Quantitative System Evaluation with DSPNexpress 2000
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ABSTRACT: This paper describes the software package DSPNexpress 2000, a tool for the quantitative evaluation of systems specified in stochastic Petri nets, the Unified Modeling Language (UML), or other specification languages for discrete-event systems. Linking the DSPNexpress software to commercial UML design packages allows the effective computation of performance measures like throughput and delay for UML system specifications. The unique feature of DSPNexpress constitute numerical solvers for transient and steady-state analysis of generalized-semi Markov processes with exponential and deterministic events, which may be concurrently active. The applicability of the DSPNexpress software for practical performance and dependability projects is demonstrated by an UML specification of an alternating bit protocol. The computational effort required by DSPNexpress for transient and steady-state analysis is plotted for varying model size. Furthermore, a performance curve for a measure of interest is p...07/2000; -
Article: Quantitative System Evaluation with DSPNexpress 2000
[show abstract] [hide abstract]
ABSTRACT: This paper describes the software package DSPNexpress 2000, a tool for the quantitative evaluation of systems specified in stochastic Petri nets, the Unified Modeling Language (UML), or other specification languages for discrete-event systems. Linking the DSPNexpress software to commercial UML design packages allows the effective computation of performance measures like throughput and delay for UML system specifications. The unique feature of DSPNexpress constitute numerical solvers for transient and steady-state analysis of generalized-semi Markov processes with exponential and deterministic events, which may be concurrently active. The applicability of the DSPNexpress software for practical performance and dependability projects is demonstrated by an UML specification of an alternating bit protocol. The computational effort required by DSPNexpress for transient and steady-state analysis is plotted for varying model size. Furthermore, a performance curve for a measure of interest is p...07/2000; -
Article: The DSPNexpress 2000 Performance and Dependability Modeling Environment
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ABSTRACT: This paper describes the latest version of the software package DSPNexpress, a tool for modeling with deterministic and stochastic Petri nets (DSPNs). Novel innovative features of DSPNexpress 2000 constitute efficient numerical methods for transient and steady-state analysis of DSPNs with concurrent deterministic transitions. In particular, DSPNexpress 2000 can perform transient analysis of DSPNs without concurrent deterministic transitions in three orders of magnitude less computational effort than the previously known method. To outreach from stochastic Petri net modeling to system specification languages used in industrial projects, DSPNexpress 2000 contains filters to the commercial design packages StateMate^TM and Together^TM. Due to an open interface, the solvers of DSPNexpress can be utilized for analysis of discrete-event stochastic systems with exponential and deterministic events specified in arbitrary modeling formalisms. Key words: Software tools for system performance and...02/2000; -
Conference Proceeding: Quantitative system evaluation with DSPNexpress 2000.
01/2000 -
Article: Adaptive performance management for universal mobile telecommunications system networks
[show abstract] [hide abstract]
ABSTRACT: In this paper, we introduce a framework for the adaptive control of universal mobile telecommunications system (UMTS) networks in order to improve bandwidth utilization of the radio channels. The key contribution of the paper constitutes the introduction of a performance management information base for dynamically adjusting the packet scheduler and admission controller. Thus, the adaptive control framework closes the loop between network operation and network control. Furthermore, the adaptive control framework can effectively deal with the different time scales of packet scheduling and admission control. Moreover, we present a traffic model for non-real-time UMTS traffic based on measured trace data. The analysis and scaling process of the measured trace data with respect to different UMTS bandwidth classes constitutes the basic concept of this traffic characterization. Using this traffic model and simulation on the IP level, the gain of employing the adaptive control framework is illustrated by performance curves for various quality of service measures.Computer Networks.
Top co-authors
Institutions
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2002–2004
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Universität Dortmund
Dortmund, North Rhine-Westphalia, Germany
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