FEC-enabled multicast routing and spectrum assignment in elastic optical networks: MILP formulation and heuristic solution

Abstract

Elastic optical networks (EONs) enable flexible resource allocation to address the rapid growth of bandwidth demand. However, dynamic resource allocation remains challenging due to time-varying traffic, spectrum continuity and contiguity constraints, and spectrum fragmentation. In this paper, we propose a mixed integer linear programming (MILP) model for multicast routing and spectrum assignment (MRSA) in EONs, integrating forward error correction (FEC) as a decision variable for multicast optimization. The proposed MILP jointly optimizes multicast tree construction, spectrum allocation, and transmission mode selection (modulation format and FEC), while considering practical network constraints such as noise, channel coding, and guard bands. Incorporating FEC enables the use of higher-order modulation formats, thereby improving spectrum efficiency through a trade-off between coding overhead and transmission reach. To address scalability limitations, we also develop a heuristic algorithm that achieves near-optimal performance with significantly lower computational complexity. Simulation results demonstrate that the proposed approach effectively reduces blocking probability compared to existing methods.