@misc{BetkerKosiankowskiLangeetal., author = {Betker, Andreas and Kosiankowski, Dirk and Lange, Christoph and Pfeuffer, Frank and Raack, Christian and Werner, Axel}, title = {Energy efficiency in extensive multilayer core and regional networks with protection}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-17154}, abstract = {Energy-efficient operation of large telecommunication networks is an important issue today and in the near future. Given that the energy consumption rises with the ever increasing demand for capacity and network speed, there is a growing interest in strategies for a sustainable network management. It is a well-known fact that traffic demands vary significantly over time, most notably in day/night- and in weekly cycles. This provides the main potential for energy-saving strategies. We study the question of how much power is necessary to operate a network with state-of-the-art hardware during peak or low-traffic times. The study respects realistic side constraints, such as protection requirements and routing schemes, and takes the special structure of an extensive nation-wide optical network, including backbone and regional sections, into account. We formulate mixed integer programming models for the corresponding optimization problems using predictions for traffic matrices, as well as state-of-the-art hardware and power models. We address questions as the following: How much energy is spent in the core and in metro regions of the network and how big are the savings in low-demand scenarios if we always assume the system power-minimum in these situations? What is the influence of different hardware on the overall energy consumption? How much do different routing schemes or protection scenarios restrict potential energy savings?}, language = {en} } @article{BetkerKosiankowskiLangeetal.2014, author = {Betker, Andreas and Kosiankowski, Dirk and Lange, Christoph and Pfeuffer, Frank and Raack, Christian and Werner, Axel}, title = {Energy efficiency in extensive IP-over-WDM networks with protection}, series = {Operations Research Proceedings 2012}, journal = {Operations Research Proceedings 2012}, editor = {Helber, Stefan and Breitner, Michael and R{\"o}sch, Daniel and Sch{\"o}n, Cornelia and Graf von der Schulenburg, Johann-Matthias and Sibbertsen, Philipp and Steinbach, Marc and Weber, Stefan and Wolter, Anja}, publisher = {Springer}, doi = {10.1007/978-3-319-00795-3_14}, pages = {93 -- 99}, year = {2014}, language = {en} } @article{BetkerGamrathKosiankowskietal., author = {Betker, Andreas and Gamrath, Inken and Kosiankowski, Dirk and Lange, Christoph and Lehmann, Heiko and Pfeuffer, Frank and Simon, Felix and Werner, Axel}, title = {Comprehensive Topology and Traffic Model of a Nationwide Telecommunication Network}, series = {Journal of Optical Communications and Networking}, volume = {6}, journal = {Journal of Optical Communications and Networking}, number = {11}, doi = {10.1364/JOCN.6.001038}, pages = {1038 -- 1047}, abstract = {As a basis for meaningful simulation and optimization efforts with regard to traffic engineering or energy consumption in telecommunication networks, suitable models are indispensable. This concerns not only realistic network topologies but also models for the geographical distribution and the temporal dynamics of traffic, as well as the assumptions on network components and technology. This paper derives such a model from the practice of a large national carrier. Applying the network and traffic model, we demonstrate its use by presenting various optimization cases related to energy-efficient telecommunication. Here, we focus on load adaptivity by employing sleep modes to the network hardware, where several constraints on the reconfigurability of the network over time are considered.}, language = {en} } @misc{BetkerGamrathKosiankowskietal., author = {Betker, Andreas and Gamrath, Inken and Kosiankowski, Dirk and Lange, Christoph and Lehmann, Heiko and Pfeuffer, Frank and Simon, Felix and Werner, Axel}, title = {Comprehensive Topology and Traffic Model of a Nation-wide Telecommunication Network}, issn = {1438-0064}, doi = {10.1364/JOCN.6.001038}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-52670}, abstract = {As a basis for meaningful simulation and optimization efforts with regard to traffic engineering or energy consumption in telecommunication networks, suitable models are indispensable. This concerns not only realistic network topologies, but also models for the geographical distribution and the temporal dynamics of traffic, as well as the assumptions on network components and technology. This paper derives such a model from the practice of a large national carrier. Applying the network and traffic model, we demonstrate its use by presenting various optimization cases related to energy-efficient telecommunication. Here, we focus on load-adaptivity by employing sleep modes to the network hardware, where several constraints on the reconfigurability of the network over time are considered.}, language = {en} } @misc{PfeufferWerner, author = {Pfeuffer, Frank and Werner, Axel}, title = {Adaptive telecommunication network operation with a limited number of reconfigurations}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-55547}, abstract = {Rising traffic in telecommunication networks lead to rising energy costs for the network operators. Meanwhile, increased flexibility of the networking hardware may help to realize load-adaptive operation of the networks to cut operation costs. To meet network operators' concerns over stability, we propose to switch network configurations only a limited number of times per day. We present a method for the integrated computation of optimal switching times and network configurations that alternatingly solves mixed-integer programs and constrained shortest cycle problems in a certain graph. Similarly to the Branch \& Bound Algorithm, it uses lower and upper bounds on the optimum value and allows for pivoting strategies to guide the computation and avoid the solution of irrelevant subproblems. The algorithm can act as a framework to be adapted and applied to suitable problems of different origin.}, language = {en} }