Benefits of sub-band virtual concatenation (VCAT) in CO-OFDM optical networks

Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM) technology is now prevailing for its advantage of high spectrum efficiency. For the CO-OFDM-based networks, most of the existing studies are based on the assumption that all the sub-bands of a CO-OFDM optical channel are carried on the same route. For better network capacity utilization, the technique of Virtual Concatenation (VCAT) in the traditional Optical Transport Networks (OTN) can be applied to a CO-OFDM optical channel that is made up of multiple sub-bands. In this paper, we study the benefits of sub-band virtual concatenation for the CO-OFDM optical networks. We develop analytical models for a single node pair and a mesh network. Analytical results indicate that virtual concatenation can significantly improve the blocking performance compared to the case of without virtual concatenation, and moreover, such an improvement becomes more significant when the bandwidths of multiple VCAT sub-bands are allocated more evenly.