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.