Wavelength Assignment Algorithms in SONET/WDM Optical Ring Networks

The terminal equipment costs associated with electronic multiplexing can comprise of a dominating percentage of the total network costs in today's backbone wavelength-division-multiplexed (WDM) synchronous optical network (SONET) ring networks. The deployment of wavelength add-drop multiplexers (WADM) allows certain wavelengths to optically bypass the nodes without being electronically terminated, thus can effectively reduce the total equipment costs if connections and channels are appropriately assigned in traffic grooming. This paper presents a series of wavelength assignment algorithms with the objective to optimize the number of required wavelengths and SONET add-drop multiplexers in both unidirectional and bi-directional rings under an arbitrary grooming factor. In our analysis, we have considered both uniform and non-uniform all-to-all network traffic. As a simple model for realistic traffic pattern, a special case of non-uniform traffic, distance-dependent traffic is analyzed in detail. Significant ADM savings are reported for different traffic scenarios using our proposed algorithms.