Network Planning With Actual Margins

Abstract

To ensure uninterrupted communication in optical transport networks, the common practice is to overprovision lightpaths in terms of capacity and physical layer performance. Overprovisioning at the physical layer is achieved using worst case assumptions and high margins in the estimation of the Quality of Transmission (QoT) when provisioning lightpaths. End-of-Life system margins are used to anticipate performance deteriorations due to additional future interference, ageing, and maintenance operations, while the design margin is used to account for inaccuracies in the QoT estimation. Such assumptions decrease network efficiency and increase the network cost. The advent of elastic optical networks and software defined networking will enable a dynamically and adaptably operated optical network. We envision an optical network that continuously senses the physical layer and optimizes connections accordingly. This enables static (e.g., worst case) physical information to be replaced by the real-time (and accurate) information. We propose an algorithm that takes into account the actual physical layer performance to provision the lightpaths with actual (just enough) margins, optimizing the decisions regarding the placement and transmission parameters of transponders and regenerators including their launch powers. Using this algorithm in a multiperiod planning scenario, we quantify the cost benefits of provisioning with actual margins as opposed to planning with worst case margins.