Computation of the Probability of Losses in Commutation Systems with Mutual Aid Selectors.

A mathematical model of a two-stage link system with mutual aid selectors is presented. Through simulation tests on such systems it has been determined that the change of intensity of the carried traffic served by the system regulated by mutual aid selectors can be approximated by a simple differential equation. A method of calculating all parameters of that equation has been given. On that basis probability of the occurrence of losses can be calculated as a function of the states introduced into the system by the mutual aid links. Two variants of the model have been considered. One is intended for systems with fully accessible group of trunks, the other is for systems in which groups of trunks create homogeneous gradings. The results of the theoretical calculations made for those models have been compared with a Monte Carlo simulation of the two-stage link systems with mutual aid selectors.