41 research outputs found

    Some aspects of the peakedness concept in teletraffic theory

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    Proofs for some conjectures of Rajaratnam and Takawira on the peakedness of handoff traffic

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    The purpose of this paper is to supplement a recent paper by M. Rajaratnam and F. Takawira (see ibid., vol.49, p.817-34, 2000), which deals with a model for the performance analysis of cellular mobile networks. The key performance measure is a second-order characteristic (peakedness) of the traffic stream that serves as a model for handoff traffic. We show that this quantity may be obtained by evaluating an explicit formula rather than by solving a set of equations. This result enables us to verify some conjectures formulated by Rajaratnam and Takawira on the basis of numerical experiments. We also show the uniqueness of the solution to a system of nonlinear equations, required in the performance analysis, as conjectured by Rajaratnam and Takawira

    Proofs for some conjectures of Rajaratnam and Takawira

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    The purpose of this note is to supplement a recent paper by Rajaratnam and Takawira ({\it IEEE Trans. Vehicular Technol.} {\bf 49} (2000) 817-834), which deals with a model for the performance analysis of cellular mobile networks. We show that the key performance quantity may be obtained by evaluating an explicit formula rather than by solving a set of equations. This result enables us to verify some conjectures formulated by Rajaratnam and Takawira on the basis of numerical experiments. We also show uniqueness of the solution to a system of nonlinear equations, required in the performance analysis, as conjectured by Rajaratnam and Takawira. \u

    On the overflow process from a finite Markovian queue

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    TOWARDS PRECISION TOOLS FOR ATM NETWORK DESIGN, DIMENSIONING AND MANAGEMENT

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    It is a critical issue in network dimensioning that the characterization of traffic at the call level should be accurate enough to provide the designer with reliable tools for dimensioning the transmission and switching capacities. Since in B-ISDN the nature of traffic is expected to be very different from traditional telephone traffic with much more complex features, therefore, new methods are needed to provide a satisfactory description. In this paper we present an approach that characterizes the traffic demand at the call level in a refined way, namely, by using a two-parameter description instead of the traditional one-parameter characterization. This approach contributes to the more accurate description of traffic demands at the call level, in order to provide the network designer and manager with precision tools to handle traffic demands and their consequences in dimensioning and related issues, while retaining simplicity, algorithmic feasibility and practical applicability

    Teletraffic engineering and network planning

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    Markovian arrivals in stochastic modelling: a survey and some new results

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    This paper aims to provide a comprehensive review on Markovian arrival processes (MAPs), which constitute a rich class of point processes used extensively in stochastic modelling. Our starting point is the versatile process introduced by Neuts (1979) which, under some simplified notation, was coined as the batch Markovian arrival process (BMAP). On the one hand, a general point process can be approximated by appropriate MAPs and, on the other hand, the MAPs provide a versatile, yet tractable option for modelling a bursty flow by preserving the Markovian formalism. While a number of well-known arrival processes are subsumed under a BMAP as special cases, the literature also shows generalizations to model arrival streams with marks, nonhomogeneous settings or even spatial arrivals. We survey on the main aspects of the BMAP, discuss on some of its variants and generalizations, and give a few new results in the context of a recent state-dependent extension.Peer Reviewe

    Introduction to Queueing Theory and Stochastic Teletraffic Models

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    The aim of this textbook is to provide students with basic knowledge of stochastic models that may apply to telecommunications research areas, such as traffic modelling, resource provisioning and traffic management. These study areas are often collectively called teletraffic. This book assumes prior knowledge of a programming language, mathematics, probability and stochastic processes normally taught in an electrical engineering course. For students who have some but not sufficiently strong background in probability and stochastic processes, we provide, in the first few chapters, background on the relevant concepts in these areas.Comment: 298 page

    Performance analysis of cellular networks.

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    Thesis (Ph.D.)-University of Natal, Durban, 2000.Performance analysis in cellular networks is the determination of customer orientated grade-of-service parameters, such as call blocking and dropping probabilities, using the methods of stochastic theory. This stochastic theory analysis is built on certain assumptions regarding the arrival and service processes of user-offered calls in a network. In the past, cellular networks were analysed using the classical assumptions, Poisson call arrivals and negative exponential channel holding times, borrowed from earlier fixed network analysis. However, cellular networks are markedly different from fixed networks, in that, they afford the user a unique opportunity: the ability to communicate while on the move. User mobility and various other cellular network characteristics, such as customer-billing, cell· layout and hand·off mechanisms, generally invalidate the use of Poisson arrivals and negative exponential holding times. Recent measurements on live networks substantiate this view. Consequently, over the past few years, there has been a noticeable shift towards using more generalised arrival and service distributions in the performance analysis of cellular networks. However, two shortcomings with the resulting models are that they suffer from state space explosion and / or they represent hand off traffic as a state dependent mean arrival rate (thus ignoring the higher moments of the hand-off arrival process). This thesis's contribution to cellular network analysis is a moment-based approach that avoids full state space description but ensures that the hand-off arrival process is modelled beyond the first moment. The thesis considers a performance analysis model that is based on Poisson new call arrivals, generalised hand-off call arrivals and a variety of channel holding times. The thesis shows that the performance analysis of a cellular network may be loosely decomposed into three parts, a generic cell traffic characterising model, a generic cell traffic blocking model and a quality of service evaluation model. The cell traffic characterising model is employed to determine the mean and variance of hand-off traffic offered by a cell to its neighbour. The cell traffic-blocking model is used to detennine the blocking experienced by the various traffic streams offered to each cell. The quality of service evaluation part is essentially afued-point iteration of the cell traffic characterising and cell traffic blocking parts to determine customer orientated grade-of-service parameters such as blocking and dropping probabilities. The thesis also presents detailed mathematical models for user mobility modelling. Finally, the thesis provides extensive results to validate the proposed analysis and to illustrate the accuracy of the proposed analysis when compared to existing methods
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