On slotted WDM switching in bufferless all-optical networks

The current λ-switching technology requires each lightpath to occupy the full bandwidth of a wavelength throughout the bufferless all-optical domain. With such a constraint, the granularity of bandwidth is so coarse that the utilization of optical fibers is considerably low. To resolve the granularity problem, a simple way is to incorporate time division multiplexing (TDM) into wavelength division multiplexing (WDM) so as to divide the entire λ-bandwidth into smaller base bandwidths. This approach is referred to as the slotted WDM (sWDM). In this paper, we define the slot labeling, mapping and assignment problems, and derive the necessary and sufficient condition that validates sWDM. We also provide simulation results of call blocking rate of sWDM in comparison with λ-switching.