Translucent Network Design From a CapEx/OpEx Perspective
Résumé
Translucent wdm network design has been widely investigated during the last 10 years. Translucent networks stand halfway between opaque and transparent networks improving the signal budget while reducing the network cost. On one hand, opaque networks provide satisfying quality from source to destination by the use of electrical reg regeneration (Re-amplifying, Re-shaping, and Re-timing) at each network node. In addition to their high cost inherent to numerous 3R regenerations, opaque networks are also constrained by the bit-rate dependence of electrical components. Transparent networks, on the other hand, do not include any electrical regeneration; therefore, the signal quality is degraded due to the accumulation of linear and non-linear effects along the signal’s route. Translucent networks include electrical regeneration at some network nodes. Among the different possible strategies for translucent network design, sparse regeneration inserts regenerators whenever needed to help establish connection requests. In this context the objective of translucent network design is to judiciously choose the regeneration sites in order to guarantee a certain quality of transmission while minimizing the network cost. In this paper, we propose to solve the translucent network design problem by introducing a heuristic for routing, wavelength assignment, and regenerator placement. This heuristic, called COR2P (Cross-Optimization for RWA and Regenerator Placement) aims not only to minimize the number of required regenerators, but also to minimize the number of regeneration sites. In this perspective, we introduce an original cost function that contributes to the optimization of CapEx/OpEx expenditures in translucent network design. In fact, the CapEx-to-OpEx ratio strongly depends on the pricing and management strategy of the carrier. In this respect, COR2P is designed in a way that its parameters can be adjusted according to carriers’ strategies. In order to discuss its different features, we compare COR2P performance with two other algorithms proposed in the literature for translucent network design.