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 five years regarding 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 appear in the field in the next twelve months. The general sense is that it will reduce the cost per transmitted gigabit per second (Gb/s), once the related faster optoelectronic interfaces become mature enough. This paper refines this consideration by quantifying the related transponders saving per Gb/s on three distinct backbone WDM networks equipped with elastic optoelectronic regenerators. It also reports how much extra network capacity stems from routing individual 64 GBaud subcarriers 75 GHz apart to serve connections, the capacities of which range 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 by avoiding internal electrical traffic regrooming.