Flexible Optical Networks: An Energy Efficiency Perspective

High energy efficiency is expected to become a mandatory design criterion in optical networks of the future. This paper investigates schemes for enhancing the energy efficiency of core optical networks based on multicarrier transmission. Such networks of the future will incorporate flexible techniques, namely: 1) adaptive modulation and coding, 2) flexible spectrum allocation, 3) wavelength conversion, and 4) traffic grooming. We investigate the problem of energy efficient routing and spectrum allocation in core optical networks incorporating these flexible techniques. We propose a heuristic solution that provides an energy minimized design of long-haul optical networks by avoiding under-utilization of network resources such as optical fibers, transponders, and amplifiers. A fixed architecture that does not employ the aforementioned flexible techniques is used as a benchmark for comparison. The numerical results in the west European (24-node US) core optical network show that the energy efficiency of the flexible architecture can outperform the fixed architecture by a factor of 4.2 (6.4) for low and 1.8 (1.9) for high traffic demands, respectively.