Using Spatial Division Multiplexing to Avoid Fragmentation in Flex-Grid Optical Networks

Spectrum fragmentation is one of the main drawbacks of Flex-Grid Optical Networks, and it becomes especially harmful under dynamic traffic conditions. When evolving from single fibre networks to spatial division multiplexed (SDM) ones, where many parallel cores/fibres are deployed, spectrum fragmentation still limits their eventual performance. In this work, the total available spectrum is partitioned according to the SDM dimension, and each one of the resulting partitions is assigned to each type of connections. This strategy is proposed as a simple method to eliminate spectrum fragmentation. By allocating all same sized connections onto the same spectral/spatial partition, the randomness in the size of the spectral voids left by torn down connections is eliminated. The proposal is numerically evaluated using different network topologies. The obtained results show that spatial partitioning is an interesting solution for spectrum fragmentation avoidance in these scenarios.