Improving link spectrum utilization in flexgrid optical networks

Flexible grid optical networks are emerging as an appealing solution for future high-speed optical transport because they can provide superior flexibility and scalability and cope with the rapid growth of Internet traffic. This work introduces some simple strategies that help improve spectrum usage in flexgrid optical networks based on limiting the bandwidth flexibility of the requested connections. Link performance improvement is demonstrated by adapting fully elastic optical networks to multibitrate optical networks where only some connection bandwidth values are allowed. With the aim of avoiding useless spectrum voids, the set of bandwidth values that connections can take is appropriately adjusted. By limiting the possible connection sizes, it is analytically demonstrated that some gain is obtained at the cost of losing some flexibility. Simulation results obtained at the link as well as at the whole network level assess the advantages anticipated by the theoretical study.