Analysis of Blocking Probability for First-Fit Wavelength Assignment in Transmission-Impaired Optical Networks

The quality of an optical signal degrades due to physical layer impairments as it propagates from a transmitter to a receiver. As a result, the signal quality at the receiver of a lightpath may not be sufficiently high, leading to increased call blocking. Consequently, an all-optical network´s routing and wavelength assignment algorithm must verify the quality of the lightpath before accepting it. In this paper, analytical expressions for the total blocking probability are derived for first-fit wavelength assignment for networks suffering from transmission impairments. The new technique effectively predicts the performance of wavelength selection techniques that consider either a single candidate channel or all channels for quality of transmission compliance. The analysis is also applicable to first-fit algorithms with different static channel orderings.