How much can sub-band virtual concatenation (VCAT) help static routing and spectrum assignment in elastic optical networks? (Invited)

Orthogonal Frequency Division Multiplexing (OFDM) has recently been proposed as a modulation technique for optical networks due to its higher spectral efficiency and superior impairment tolerance. There have been extensive studies on routing and spectrum assignment (RSA) of the OFDM-based elastic optical network, of which most focus on a single route for each lightpath service. In this paper, we study the RSA problem for the elastic optical network considering the multi-path subband virtual concatenation (VCAT) technique that allows the sub-bands of a VCAT lightpath connection to be transmitted over different routes. We develop integer linear programming (ILP) models to optimally solve the problem. We evaluate the benefit of the multi-path sub-band VCAT technique for the RSA problem through comparing with the non-VCAT case. In addition, because of the limitation of synchronization in the sub-band VCAT technique, we set a maximal distance difference among the sub-band paths of a VCAT connection to evaluate how the limitation can impact the RSA performance. We find that the multi-path sub-band VCAT technique shows a stronger benefit in a network with a higher nodal degree.