## Abstract

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.

© 2012 OSA

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