On the approximation of the slot occupancy pattern in a DQDB network

The authors present a novel approach to distributed queue dual bus (DQDB) modeling. The innovative aspect lies in the representation of the slot-occupancy-pattern process on the forward bus. In the literature, this process has been modeled as a Bernoulli process, implying that the status (empty/busy) of consecutive slots is independent. Results presented, however, show that even at light loads the interdependence between slots is significant. The model captures some of this interdependence by using a discrete-time first-order Markov process for the slot-occupancy-pattern process on the forward bus. A simplified DQDB network is identified for which a closed formula is derived for the joint probability density function for the slot occupancy pattern of two consecutive slots. The accuracy of the results was investigated with simulation