Analytical models for QoT-aware RWA performance

The very vast majority of QoT-Aware Routing and Wavelength Assignment (RWA) algorithms are evaluated through extensive simulations. Full-scale simulations, however, tend to be too lengthy for network planners who only seek to know, in the early stages of the design of a network, a rough estimate of the traffic demand blocking probability. An alternate solution to this dimensioning problem is to utilize fast analytical models to estimate the blocking rate in an QoT-aware network. The accuracy of analytical blocking probability estimators may be somewhat degraded but it should be sufficient for a designer to make a decision on the dimensioning of a network. Network designs that are shown to be clearly unacceptable (e.g. too high a blocking rate) when evaluated by an analytical technique can be ruled out and more promising designs kept for more thorough investigations. This chapter briefly reviews and compares analytical techniques for QoT-unaware RWA algorithms, and presents two analytical techniques to model IA-RWAs: one targets RWA with random-pick wavelength assignment, and the other is suited to RWA with first-fit wavelength assignment.