Routing and Wavelength Assignment Problem in PCE-Based Wavelength-Switched Optical Networks

As a key problem in wavelength-switched optical networks (WSONs), in which wavelengths are the most important resources, the routing and wavelength assignment (RWA) problem has been researched extensively. Due to the advantages of path computation in multilayer and multidomain networks, especially in multiconstraint scenarios, the path computation element (PCE) has been introduced into WSONs, which provides a better approach to the solution of the RWA problem in WSONs. This paper focuses on the RWA problem in PCE-based WSONs. A PCE-based routing framework and two PCE-based routing models are first designed, and then two distributed resource reservation schemes based on forward reservation protocol (FRP) and backward reservation protocol (BRP) are proposed and simulated in a PCE-based WSON. Finally, eight PCE-based RWA schemes are proposed in WSONs, the performances of which have been investigated and validated using the discrete event simulation tool OMNeT++. Numeric results show that the RWA (first-fit) scheme has the best performance in terms of blocking probability and average delay time.