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Interference-and-security-aware distance spectrum assignment in Elastic Optical Networks

In Elastic Optical Networks (EONs), two communications requests sharing common fiber links have to be separated in the spectrum domain by a guard band to prevent the interference or satisfy the security requirement, since there are types of physical impairments or attacks in the optical layer. For different interference or security levels, the size of guard band should be adapted, while it is supposed to be identical in most of the literature. To be more agile and realistic, we rise a new spectrum assignment model called Distance Spectrum Assignment (DSA): the size of guard band between two communications sharing a common fiber link varies according to the specific circumstance, and the goal is to minimize the maximum index of frequency slots assigned to satisfy all the guard band constraints. Since DSA is a strongly NP-hard problem, we propose an Integer Linear Program (ILP) model for computing the optimal solution. For solving the DSA problem in large-scale EONs, we develop a heuristic algorithm with time complexity O(n3Δ), where n is the number of requests and Δ is the maximum degree of the conflict graph. We prove that the proposed algorithm achieves an approximate ratio of O(log(n)) in complete conflict graphs. Numerical results demonstrate the proposed heuristic algorithm can find near-optimal spectrum assignments for solving the DSA problem in general topologies.