This is a post-peer-review, pre-copyedit version of an article published in Photonic Network Communications. The final authenticated version is available online at: https://doi.org/10.1007/s11107-017-0717-9.In an increasingly competitive market environment with smaller product offer differentiation, a continuous maximization of efficiency, while guarantying the quality of the provided services, remains a main objective for any telecom operator. In this work, we address the reduction of the operational costs of the optical transport network as one of the possible fields of action to achieve this aim. We propose to apply cognitive science for reducing these costs, specifically by reducing operation margins. We base our work on the case-based reasoning technique by proposing several new schemes to reduce the operation margins established during the design and commissioning phases of the optical links power budgets. From the obtained results, we find that our cognitive proposal provides a feasible solution allowing significant savings on transmitted power that can reach a 49%. We show that there is a certain dependency on network conditions, achieving higher efficiency in low loaded networks where improvements can raise up to 53%.Peer ReviewedPostprint (author's final draft

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