Nyquist-WDM-Based Flexible Optical Networks: Exploring Physical Layer Design Parameters

We focus on Nyquist-WDM-based flexible optical networks and examine the impact of introducing flexibility in physical layer design parameters on the network level performance. The considered physical layer parameters include the modulation format, the symbol-rate, the inter-subcarrier spacing, the inter-superchannel spacing, and the launch power. In order to examine the impact of allowing the symbol rate to be tuned on a super channel basis, three alternative launch power schemes are considered: (i) optimum launch power, (ii) constant launch power, and (iii) constant power spectral density. Case study results from a realistic reference core network highlight the identified trade-offs with respect to the utilized spectrum and the required transponders. It is shown that significant savings can be achieved by allowing the symbol rate to be dynamically tuned under different launch power options.