Engset loss models for an OBS/OPS node with shared wavelength conversion

Asynchronous bufferless OBS/OPS core nodes behave as loss systems and therefore, widely analyzed under traditional Erlang and Engset loss models. Additionally, it has been shown that the Engset traffic assumptions are more realistic with a correction in the offered load. This correction is proposed due to the fact that in case of loss, the source cannot offer a new packet while the input wavelength is busy in transmitting a lost packet. This effect is more evident in OBS switches which deals with large burst lengths compared with packets. In this study, Engset traffic model with and without correction in the offered load is used to analyze a switch using the shared wavelength conversion. We show that the degree of wavelength conversion also effect the blocking of the switch significantly and in the switches with small and medium port counts the effect of blocked inputs due to packets/bursts should not be ignored. Continuous time Markov chains have been used for analysis and expressions have been derived to evaluate the time, traffic and call blocking.