Energy-efficient design for multi-granular optical transport networks with optical reach consideration

Energy consumption of the optical backbone is expected to contribute to a significant portion of the energy consumed by the telecommunication networks. As an enhanced bandwidth utilization and management extent of the optical Wavelength Division Multiplexing (WDM) technology, multi-granular switching concept has been shown to guarantee energy savings when compared to the traditional traffic grooming. However, Multi-Granular Optical Transport Network (MG-OTN) design and planning still calls for legitimate and self-contained design specifications. In this paper, we revisit the Routing and Multi-Granular Path Assignment (RMGPA) problem by having the objective of minimized power consumption and integrating the optical reach limitation of optical signals in the design and planning problem. The new problem is formulated as a Mixed Integer Linear Programming (MILP) model. For large scale design scenarios, we propose an efficient heuristic approach that is capable of solving the power minimization problem in feasible runtime. The heuristics is verified within 2% average approximation to the MILP solutions under small scale scenarios, and the numerical results of the design and planning problem heuristic show that significant power savings up to 55% in MG-OTNs can be achieved with the proper selection of the wavelength capacity, waveband size, number of wavebands per fiber, and the value of the optical reach. Furthermore, the proposed heuristic has been shown to guarantee high fairness among the nodes with respect to the power fairness index, which is at the order of 92-99% under various traffic scenarios.