Decomposed Request Scheduling in SnF OCS Networks

Scheduling a data transfer in Store-and-Forward (SnF) networks has to deal with the spatial and temporal arrangement of the request, and is thus much more complicated than the routing-alone problem. In this research, we first argue that even though a multilayer graph based approach, as has been proposed in our prior research, is intuitively viable for joint spatial-temporal scheduling, the computational and spatial complexity of the approach is far from optimal, limiting its use in large scale networks. We then propose a decomposed solution and specific algorithms for both subproblems. The solution can reduce spatial and computational complexity from O(N²*L²) to O(N*L), in which N and L are the number of data-centres and state changes in the network, respectively. Simulation results show that in a moderate sized network with frequent state changes, the computing time of request scheduling can be reduced by 600 times. We conclude that the decomposed SnF scheduling has the potential of analysing complex networks with frequent state changes.