2,064 research outputs found
The pseudo-self-similar traffic model: application and validation
Since the early 1990¿s, a variety of studies has shown that network traffic, both for local- and wide-area networks, has self-similar properties. This led to new approaches in network traffic modelling because most traditional traffic approaches result in the underestimation of performance measures of interest. Instead of developing completely new traffic models, a number of researchers have proposed to adapt traditional traffic modelling approaches to incorporate aspects of self-similarity. The motivation for doing so is the hope to be able to reuse techniques and tools that have been developed in the past and with which experience has been gained. One such approach for a traffic model that incorporates aspects of self-similarity is the so-called pseudo self-similar traffic model. This model is appealing, as it is easy to understand and easily embedded in Markovian performance evaluation studies. In applying this model in a number of cases, we have perceived various problems which we initially thought were particular to these specific cases. However, we recently have been able to show that these problems are fundamental to the pseudo self-similar traffic model. In this paper we review the pseudo self-similar traffic model and discuss its fundamental shortcomings. As far as we know, this is the first paper that discusses these shortcomings formally. We also report on ongoing work to overcome some of these problems
Likelihood inference for exponential-trawl processes
Integer-valued trawl processes are a class of serially correlated, stationary
and infinitely divisible processes that Ole E. Barndorff-Nielsen has been
working on in recent years. In this Chapter, we provide the first analysis of
likelihood inference for trawl processes by focusing on the so-called
exponential-trawl process, which is also a continuous time hidden Markov
process with countable state space. The core ideas include prediction
decomposition, filtering and smoothing, complete-data analysis and EM
algorithm. These can be easily scaled up to adapt to more general trawl
processes but with increasing computation efforts.Comment: 29 pages, 6 figures, forthcoming in: "A Fascinating Journey through
Probability, Statistics and Applications: In Honour of Ole E.
Barndorff-Nielsen's 80th Birthday", Springer, New Yor
A Mathematical Approach to Order Book Modeling
Motivated by the desire to bridge the gap between the microscopic description
of price formation (agent-based modeling) and the stochastic differential
equations approach used classically to describe price evolution at macroscopic
time scales, we present a mathematical study of the order book as a
multidimensional continuous-time Markov chain and derive several mathematical
results in the case of independent Poissonian arrival times. In particular, we
show that the cancellation structure is an important factor ensuring the
existence of a stationary distribution and the exponential convergence towards
it. We also prove, by means of the functional central limit theorem (FCLT),
that the rescaled-centered price process converges to a Brownian motion. We
illustrate the analysis with numerical simulation and comparison against market
data
Markovian arrivals in stochastic modelling: a survey and some new results
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
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