| Summary: | 碩士 === 國立臺灣科技大學 === 工程技術研究所 === 81 === We consider an approximation scheme for estimating point-to-
point and multicast connection blocking probability in loss
networks (e.g.circuit switch network) with contiguous bandwidth
allocation scheme. First, we consider single-link network.
Although we can use Markov process to describe the system and
compute steady state probability distribution, the number of
states of the Markov process increases rapidly with the
capacity of link. Therefore, it is very time consuming to
compute steady-state probability distribution for even networks
of practical size. We suggest that the aforementioned Markov
process be approximated by multirate, state-dependent birth
death process. Thus we can reduce the number of states
significantly, that is, the computing complexity is reduced. In
order to verify its accuracy, we consider three kinds of
traffic loads: light, moderate, and heavy. Next we consider
multilink network.To reduce the complexity for computing steady
state probability, we further suggest using reduced load
approximation. This approximation assumes that blocking occurs
independently from link to link and that the offered load to a
link is reduced by blocking on other links. We futher assume
each link can be approximated as a multirate, state dependent
birth death process. This leads to a set of nonlinear fixed
point equation with the unknowns being link blocking
probabilities. We suggest using repeated substitutions to solve
the nonlinear fixed point equations.Two special network
topologies, 4-link and 6 link networks, are used to verify the
accuracy and computing complexity of the approximation scheme.
Numerical results from both the approximation scheme and
computer simulation are compared.
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