LAUSR

Abstract As the most promising candidate for upgrading today’s fixed-grid networks, the concept of flexible grid has been introduced into elastic optical networks (EONs), which enables on-demand spectrum assignment and adaptive modulation formats. Considering the cost of network upgrade, it is practical and economical for network operators to adopt the gradual migration from fixed grid to flexible grid optical network. Thus, a mixed grid optical network is a typical network scenario in the near future where fixed grid technology coexists with flexible grid technology. Spectrum fragmentation is regarded as a significant issue in flexible grid optical network. Compared with flexible grid, with heterogeneous spectral widths, more spectrum fragmentation is induced in mixed grid optical networks. Therefore, spectrum fragmentation in mixed grid optical network is actually much more challenging than flexible grid optical network. This paper first analyzes the resource allocation and proposes a novel spectrum defragmentation algorithm based on service differentiation in mixed grid optical networks. The performance of the proposed algorithm is evaluated in simulation with different traffic profiles. Simulation results verify that the proposed algorithm can effectively reduce the blocking probability by consolidating spectrum fragmentation in mixed grid optical networks.