Routing and Wavelength Assignment in WDM Networks with Bounded-Degree Tree and Tree of Rings Topologies

In all-optical networks that use wavelength division multiplexing (WDM) technique, a challenging problem called the routing and wavelength assignment problem (RWA) is modelled as that connection requests must be assigned paths and wavelengths such that intersecting paths receive different wavelengths, and the goal is to minimize the number of wavelengths used. Besides the tree, another popular network topology is the tree of rings which is obtained by interconnecting rings in a tree structure such that any two rings share at most one node. A polynomial-time optimal algorithm and an approximation algorithm are given for the RWA problem in bounded-degree tree and tree of rings networks, respectively.