Granularity in all-optical WDM networks for large geographical areas

Granularity is a key issue in the design of an optical layer of a transport network. In fact, the choices of the number of wavelength division multiplexing (WDM) channels and of the bit rate of each channel have a significant impact on the design of the network nodes, and influence both the network management and the transmission performance. In a recent paper we analyzed this issue, assuming no-regeneration along the transmission path through the network, providing simulation results in some relevant cases. In this paper, we report results of the analysis extended to large geographical areas, where the transmission spans can be long enough to give rise to further transmission impairments due to nonlinear effects during fiber propagation. In particular, the transmission performance for all-optical meshed network, with several OXC crossed, is studied considering different link capacities.