The capacity expansion approach in optical transport networks with fixed and flexible grids

This paper addresses the issue of the backbone infrastructure capacity planning of WDM optical network related to upgrading of the existed fixed grid with the flexible grid technology. In order to determine the appropriate time for making the technology migration we propose a novel approach that is based on the penalty function as well as on the Blocking Bandwidth Ratio (BBR) metric. The penalty function depends on the forecasted traffic demands and relates to the congestion level of the considered link. According to these indicators the upgrade plan is determined. Through the case study the proposed approach is demonstrated.