Optical transparency and network energy efficiency

Summary from only given. Communication networks have been identified as an important enabling technology for realizing dramatic reductions in energy consumption across many sectors of our society, including electric power delivery (smart grids), transportation (tele-presence and traffic management), and building controls. Recent reports indicate that by 2020 information and communication technologies could offset their own carbon footprint by five-fold through savings realized in other areas. This benefit presupposes the sustainable growth of communication networks, even as the Internet continues to expand exponentially. Historically optical networks have benefited from exponential increases in transmission capacity and interface speeds. However, recent studies have demonstrated that spectral efficiencies of optical transmission systems are approaching channel capacity limits, indicating that efficiency improvements through bandwidth increase may be limited. This brings focus to network energy efficiency, measured as the power of the network equipment per unit bandwidth delivered to the user, as an important dimension for continued efficiency improvements. Optical transparency enables efficient use of network resources through optimized wavelength routing and switching. Some of this translates directly into reduced electronic processing and consequently reduced energy consumption. Nevertheless, there are further opportunities for power reductions including re-use of stranded resources through reconfiguration, dynamically varying capacity to follow traffic fluctuations over time, and changing network configuration to take maximum advantage of available renewable energy resources. In this work we build transaction-based network models to examine the relative benefit and potential opportunities for improving overall network energy efficiency. These models include projected traffic growth through 2020 for different network services. The relative impact of optical techno- - logy efficiency measures is included to understand benefits to the overall network efficiency.