Computing Call Blocking Probabilities in Wavelength Routing Networks
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1999-03-31
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Abstract
We study a class of circuit switched wavelength routing networks with fixed or alternate routing, with or without converts, and with various wavelength allocation policies.We first construct an exact Markov process and an approximate Markovprocess which has a closed-form solution for a single path. We alsodevelop an iterative decomposition algorithm to analyze long paths with orwithout wavelength converters effectively. Based on this algorithm, we thenpresent an iterative path decomposition algorithm to evaluate the blocking performance of mesh topology networks with fixed and alternate routing accurately and efficiently.The decomposition approach can naturally capture the correlation of both link loads and link blocking events, giving accurate results for a wide range of loads and network topologies.Our model also allows non-uniform traffic, i.e., call request arrival rates that can vary with the source-destination pair, and it can be used when the location of converters is fixed but arbitrary.Our algorithm represents a simple and computationally efficient solution to the difficult problem of computing call blocking probabilities in wavelength routing networks. Finally we show through numericaland simulation results that the blocking probabilities for the randomwavelength allocation and the circuit-switched case provide upper and lowerbounds on the blocking probabilities for two wavelength allocation policiesthat are most likely to be use in practice, namely most-used and first-fitallocation. Furthermore, we demonstrate that using these two policieshas an effect on call blocking probabilities that is equivalent toemploying converters at a number of nodes in the network.
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PhD
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Computer Science
