Planning flexible optical networks under physical layer constraints

We consider the planning problem of a flexible optical network. Given the traffic matrix and the transponders' feasible configurations that account for the physical layer, we formulate the planning problem considering both the use or not of regenerators. Demands are served for their requested rates by choosing the route, selecting the transmission configuration, breaking the transmissions in more than one connection and placing regenerators, if needed, and allocating the spectrum to them. The objective is to serve the traffic and find a solution that is Pareto optimal with respect to the maximum spectrum used and the cost (number and type) of transponders used. The problem definition and the proposed algorithms are general and applicable to flex-grid as well as fixed-grid networks. We start by presenting algorithms based on integer linear programming formulations for transparent and translucent networks (without or with regenerators) and we continue by presenting heuristic algorithms. Using input driven by transmission studies on optical orthogonal frequency-division multiplexing (OFDM)-based networks we evaluate the performance gains that can be obtained by an OFDM over a mixed line rate fixed-grid WDM optical network.