Fragmentation-aware routing, wavelength and spectrum assignment (RWSA) scheme in flex-grid optical networks

Abstract

Flex-grid optical network is a promising solution to meet the ever increasing varied traffic demands by virtue of its capability to efficiently utilize the limited spectral resources in fiber optic communication. However, in a dynamic network scenario, setting up and tearing down connections with heterogeneous data rates can fragment the spectral resources into non-contiguous small spectrum voids, thereby rendering them unusable for future connections, especially those with large bandwidth requirements. This results in poor spectrum utilization as well as potentially high blocking probability in flex-grid optical networks. We propose a novel fragmentation-aware routing, wavelength and spectrum assignment (RWSA) scheme for flex-grid optical networks. The objective of this scheme is to prevent or curtail spectrum fragmentation, by compacting the occupation of spectrum resources in the network while allocating them to the incoming connections, using a metric defined in our study. Thereby, the scheme is aimed at reducing blocking probability leading to overall increased spectrum utilization of the network. In our work, we present a comparative study of the performance of the proposed RWSA scheme with that of the commonly employed first-fit based RWSA scheme for flex-grid optical networks, and demonstrate the improvement achieved under different traffic scenarios.