Design with low cost of equipment for metro filterless optical networks

Emerging 5G services are pressuring optical metro networks with unprecedented capacity requirements. To moderate the growth of operators’ expenses, several technical directions to design low-cost optical networks are being investigated. In this study, we elaborate on what we believe to be a novel approach to designing low-cost metro networks by jointly (i) removing costly wavelength selective switches (WSSs) and enforcing filterless optical network (FON) architecture, (ii) reducing the number of optical amplifiers (OAs), and (iii) reducing the number of installed transponders by intelligently placing amplifiers to maximize signal quality (SNR), so as to employ higher-order modulation formats. To quantify the achievable cost-reduction, we develop a quality-of-transmission (QoT)-aware planning tool, based on a genetic algorithm, for the joint optimization of fiber tree establishment (inherent to FON), OA placement, and transponder upgrades, considering multiyear traffic evolution. Results obtained over realistic metro topologies show that the proposed design achieves overall (8%–17%) equipment cost savings compared to baseline optical network deployment with WSSs in nodes and conventional placement of OAs.