Performance analyses of wavelength assignment algorithms in wideband fixed-grid/flex-rate optical networks

Expanding spectral usage beyond the C band in wavelength-division multiplexing (WDM) networks offers the advantage of increased capacity without the need for new fiber infrastructure deployment. However, to optimize network performance within this expanded spectrum, it is crucial to adapt the resource allocation procedure that is responsible for establishing new lightpaths. This adaptation must account for new characteristics, such as variations in the quality of transmission (QoT) among different spectral bands. Additionally, advancements in multi-rate transceivers allow for dynamic adjustments to channel bit rates based on their individual QoTs, thereby introducing another dimension to this problem. In this study, we apply several wavelength assignment algorithms to wideband fixed-grid/flex-rate optical networks and compare their performances. Our results indicate that the algorithm with titled lower margin (LM), which prioritizes channels with QoTs closest to the required threshold of a specific modulation format, can perform best in terms of delivered traffic and average channel bit rate.