How 64 GBaud optical carriers maximize the capacity in core elastic WDM networks with fewer transponders per Gb/s

Following the extensive investigations of the research community throughout the last 5 years regarding the transmission performance when roughly doubling the channel symbol rate in WDM systems from generic 32 GBaud to more than 60 GBaud, this evolution is about to become a reality in the field by the next 12 months. The common understanding is that it will reduce the cost per transmitted Gb/s, above all once the related faster optoelectronic interfaces will be mature enough. This paper refines this consideration by quantifying the related transponders saving per Gb/s on 3 distinct backbone WDM networks. In parallel, it reports how much extra network capacity stems from routing individual 64 GBaud subcarriers 75 GHz apart to serve connections capacity of which ranges from 100 Gb/s to 1 Tb/s. It eventually discusses the impact on the network performance when constraining the regenerators placement along the light paths of the accommodated services or when simplifying the elastic regenerators.