Impairment-aware design of translucent DWDM networks based on the k-path connectivity graph

In this paper we propose a design procedure based on comprehensive integer linear programing (ILP) for translucent optical transport networks (OTNs), exploiting an extended version of the so-called “connectivity graph.” For the first time to the best of our knowledge, we propose a mathematical approach that covers the manifold challenges of a realistic optical layer OTN design, jointly solving the regenerator placement problem (RPP) and the routing, fiber and wavelength assignment with regenerator problem (RFWA-RP). As a first contribution, we extend the concept of the connectivity graph to a k-path (k-p) connectivity graph. Second, the formulation addresses the problem of planning the number of dense wavelength division multiplexing systems, jointly solving the RPP and placing transponders. Third, we consider regeneration devices as wavelength converters also, showing the benefits arising from that aspect disregarded in the existing impairment-aware (IA) ILP formulations based on the connectivity graph. Finally we compare over different networks the results of our design procedure with those achieved by a hybrid method that combines a simplified IA-ILP formulation with a greedy heuristic. Moreover, an analytical framework to evaluate the network cost in terms of capital expenditure and operational expenditure is also presented. We show that the k-p connectivity graph represents a cost-effective tool for network design, as it allows one to greatly reduce the number of resources needed in both the protected and the unprotected scenarios.