Centralized vs. Distributed Approaches for Encompassing Physical Impairments in Transparent Optical Networks. - Piero Castoldi; Filippo Cugini; Luca Valcarenghi; Nicola Sambo; Esther Le Rouzic; M. J. Poirrier; Nicola Andriolli; Francesco Paolucci; Alessio Giorgetti (ONDM, 2007)