Dynamic routing and wavelength assignment in transparent WDM networks with amplifiers' power constraints

In a wavelength-routed optical network, the signal remains in the optical domain over the entire route (lightpath) from source to destination node. Thus, while propagating through the network, the signal quality may degrade as it encounters physical impairments. In this paper, we study the establishment of new connections in such a network in the presence of amplifier optical power constraints. In particular, a Multicost Impairment Aware Online RWA (IA-RWA) algorithm is extended to include amplifier power constraints. The extended algorithm accounts not only for the channel utilization in the network but also for the amplifiers' possible saturation, which change as new connections are established or released, in order to calculate the noise variances that correspond to physical impairments on the links. We find that when these effects are taken into account the two algorithms achieve similar performance when the amplifiers operate in the linear region. In the case, however, where the amplifiers are saturated, the extended algorithm exhibits better performance compared with the previously proposed algorithm, in terms of blocking probability and frequency of reroutings required.