Strategies and benefits of deploying ultralow-loss fiber links in an elastic optical network

Superchannels using efficient formats for modulation [e.g., 16-quadrature amplitude modulation (QAM), 64-QAM] and transmitting high data rates (e.g., 400 Gb/s, 1 Tb/s, or even 10 Tb/s) are expected to dominate in future optical networks. Ultralow-loss (ULL) fibers promise greater efficiencies for carrying such superchannels, and the current trend is to deploy ULL fibers for new network links. However, this would generally be done in a staged manner because of budgetary constraints, strategically selecting the links for new ULL fiber deployments so as to maximize network performance improvement at each stage. We address this problem in the context of an elastic optical network and propose approaches for doing this for both static and dynamic traffic demands. For static traffic demands, we formulate the problem using mixed-integer linear-programing models and also propose efficient heuristic algorithms. For dynamic traffic demands, we propose a deployment strategy based on lightpath blocking because of inadequate optical signal-to-noise ratios. Simulation studies show the efficiency of the proposed strategies and an interesting performance saturation behavior in test scenarios.