Evaluating the performance of ultra-fine spectrum granularity flexible optical networks

Flexible optical networking has been proposed as a promising transport solution for future core networks, since it offers superior flexibility in terms of optical spectrum utilization and can thus efficiently accommodate the rapid growth of Internet traffic. This novel type of optical networking paradigm and the associated physical-layer technologies (i.e. optical switches and transponders) have evolved lately to support ultra-fine-granularities, much lower than those of the conventional ITU-T 50-GHz fixed grid and even the new flexgrid of 12.5 GHz. Given the improved capabilities of the optical network physical layer, we seek to identify the targeted specifications of the associated sub-systems in order to derive the maximum benefits and efficiency for the optical network. Following an extensive set of network level performance simulation studies we have determined the possible targeted specifications. We found that spectrum granularities in the range of 2.5 GHz to 3.125 GHz give excellent performance results and only a very small gain can be obtained in an entirely gridless scenario. In this paper we will outline the performance of this new type of flexible optical networks for optically filtered single-channel and super-channel Nyquist WDM transmission and will present comparison results with other competing and legacy solutions.