OPEX Savings Based on Energy Efficient Strategies in NREN Core Optical Networks

The common practice for optical network operators today is to deploy optical resources based on overprovisioning towards the maximum expected amount of traffic in the network. This is a safe strategy and it takes into account the currently static nature of the optical network design, where new wavelengths and new circuits are established based on a predefined dimensioning plan. However, because of the continuous increase in the overall traffic demand (estimated to be between 30 % and 60 % per year [1] ) as well as due to the more and more heterogeneous behavior of the incoming requests – the overprovisioning deployment strategy becomes less and less efficient. This is a challenging aspect especially in NREN environments where new and state of the art s ervices are being proposed or requested (e.g. Photonic Services) and their requirements are often hard to be predicted. Moreover, in terms of energy consumption, significant savings can be obtained and accounted into OPEX (Operational Expenditure) by takin g into account a more efficient usage of the opto - electronic resources (such as transponders or regenerators). There are more strategies proposed in the literature to enhance the energy consumption in core optical networks. One proposal is to define differ ent operational states for the optoelectronic components – OFF, IDLE and ON – which correspond to different levels of energy consumption. Another solution is to use advanced transponder architectures (i.e. elastic or flexible transponders , introduced in [ 2] ) which are able to tune the symbol - rate of an optical circuit and thus determine a variable consumption for the transponder. Simulations show that when deploying the proposed energy reduction strategies and while taking into account weekly fluctuations and traffic growth, the overall energy consumption can be reduced with 48% for NORDUnet network scenario and with 50% for a GEANT network scenario.