Multi-layer high-speed network design in mobile backhaul using robust optimization

The multi-layer network design problem and the mobile backhaul problem are both interesting from the perspective of choosing the correct technology and protocol as well as choosing the appropriate node architecture to meet a wide variety of overlay traffic demands. Network operators encounter two variants of the multi-layer/backhaul problem: 1) For a given set of uncertain traffic demands, which set of technologies would minimize the network cost? 2) Would these technology choices be invariant to the changing traffic demands? This problem of technology choice can essentially be abstracted to a switching and grooming problem with the added complexity of unknown traffic demands, which at best may be approximated to some known statistical parameters. To solve this complex switching and grooming problem, our goal is to make use of the theory of robust optimization with the assumption of known boundary conditions on traffic. We present a comprehensive optimization model that considers technology choices in terms of protocols, physical layer parameters, link boundary conditions, and transmission layer constraints. Validated by simulations, our model shows the stand-off conditions between various technologies and how a network operator must take proactive steps to be able to meet requirements of the next-generation networks and services. Our main result showcases network design using two technology alternatives [1) Multi-Protocol Label Switching (MPLS) + Optical Transport Network (OTN) + Reconfigurable Optical Add-Drop Multiplexer (ROADM) and 2) Carrier Ethernet (CE) + OTN + ROADM] and the effect of robustness on these choices. A heuristic is used for comparative purposes as well as to exhaustively model the dynamic case of brown-field networks.