A node configuration algorithm with bandwidth bottleneck resolution for WDM ring networks

The wavelength-division multiplexing (WDM) technology has been extensively studied and actually deployed as a key technology to solve global information explosions by multiplexing plural signal paths using different wavelengths into one optical fiber. Among WDM-based network architectures, this article focuses on a double-ring one for a next-generation metropolitan area network (MAN), where each node is normally equipped with two pairs of fast-tunable transmitters and wavelength-fixed receivers (TT-FR) as interface to two fibers. To enhance the network performance, additional transmitters/receivers at nodes and receiver wavelengths should be assigned optimally, so that the bandwidth bottleneck can be resolved both on nodes and fiber links. This article formulates this node configuration problem with bandwidth bottleneck resolution as a combinatorial optimization problem, and proves the NP-completeness of its decision version. Then, it presents the two-phase heuristic algorithm composed of a greedy method and a variable depth search (VDS) method. Our algorithm is evaluated through extensive network simulations, where the results support the effectiveness of this joint assignment approach.