Blocking Analysis of Limited-Reconfigurable Optical Networks

The blocking performance of limited-reconflgurable all-optical networks is investigated in this paper. Reconfigurability is achieved by reconflgurable optical add-drop multiplexers (ROADMs) and tunable transponders. An analytical model is developed adopting a share-per-node model for the sharing of transponders within a reconfigurable node. The set of wavelengths that can be added/dropped at a reconfigurable node depends on the constraints of ROADMs as well as the (possibly limited or narrowly) tunable transponders. The size of the wavelength set to which a transponder is tunable (tuning range), and the number of transponders are the key parameters that affect the blocking. A lightpath request can be established depending on the transponders' ability to tune to the available wavelengths along the route. We call this constraint as wavelength termination constraint. Both analytical and simulation results show that narrowly tunable transponders achieve a similar performance as widely tunable transponders. The effect of the number of transponders or the number of ports of a ROADM on blocking is also investigated.