Probability Distribution of Delays for Store-and-Forward Traffic Mixed with Direct Traffic

This paper discusses the delay probability distributions of store-and-forward (S/F) traffic sent over the same trunks as direct traffic. The operating principles for mixing are the same as described in a previous paper, i.e., the S/F traffic is held back until the trunk group is not congested with the direct traffic: a specified number of trunks are held in reserve for the possible arrivals of direct traffic. In this study, only that portion of the total S/F message delay caused by the presence of the direct traffic on the trunks is investigated. The effect that the S/F traffic has on the distribution of delays is assumed negligible. Because of this assumption, the results apply when the load of the S/F traffic is small compared to direct traffic or, when the load of S/F traffic is appreciable, the results apply to a small portion of the S/F traffic which, because it enjoys the privilege of priority, is placed at the head of the queue. A method of computation and some specific results are presented. The numerical results are for trunk groups of from 2 to 48 trunks. Exponentially distributed holding times of the direct traffic are assumed.