Incremental Network Upgrade Problem with No-Disruption Constraint

This paper addresses the challenge of incrementally upgrading Single-Band Elastic Optical Networks (SB-EONs) to Multi-Band Elastic Optical Networks (MB-EONs) to accommodate growing traffic demands. The study formulates the problem as a multi-period network optimization problem, aiming to minimize the total discounted cost of upgrades while ensuring uninterrupted traffic flow. To solve this problem, we propose a Load-Based Upgrade Algorithm (LBUA) that iteratively identifies overloaded fibers, reroutes traffic, and schedules upgrades. Additionally, a heuristic algorithm is introduced. The study demonstrates that the proposed heuristic algorithm outperforms the LBUA.