An analysis of an integrated circuit-and packet-switched telecommunications system

Trends of future requirements for switched digital communications systems show an increasing diversity of traffic characteristics, such as for voice and interactive data. The paper analyzes a multiplex structure for mixing these two classes of traffic, utilizing a master frame format of a time division statistical multiplex facility where synchronous and asynchronous traffics are multiplexed onto the same trunk line. Relevant queueing equations are developed and expressions for the loss probability of voice and the expected waiting time for data are presented. The discussion concerns the fixed boundary case in which voice channels are used for voice traffic only and data channels for data only, and the movable boundary case in which while the voice traffic may only use voice channels, the unoccupied voice channels are made available to the data traffic. Numerical results are given for illustrative examples. The movable boundary solution is shown to be clearly superior to that achieved by separate transmission facilities. Future work will extend the results to consider a system with varying service capacity at each gating period.