Comparison of switching policies in terms of switching cost and network performance in static SDM-EONs

In this paper, we concentrate on the comparison of different switching policies, as well as their corresponding spatially-spectrally flexible super-channel transmission technologies, in static SDM-EONs. These switching policies are different due to their different spatial switching granularities and/or whether the space lane change (SLC) is supported. According to our simulation results, the switching policy with a finer switching granularity can achieve better network performance in terms of required frequency slices in the networks but meanwhile results in higher device cost. Moreover, we find that the application of SLC can only provide negligible improvements (0.1% ~ 3.1%) on network performance. SLC is encouraged only when the spectrum resource is highly valued by network operators compared to the additional device cost it brings. Moreover, in some previous works, the application of SLC can achieve a 7% ~ 14% improvement on the network throughput in dynamic network scenarios, especially when a finer spatial switching granularity is applied. Consequently, the results in this paper suggest that such an improvement is likely to be achieved by the means of network planning, such as the design of an efficient algorithm considering spectrum defragmentation, because if the re-routing/re-assignment of spectrum is allowed, the dynamic scenario can be treated as a sequence of static scenarios that change with time.