APPROXIMATE TECHNIQUES FOR GENERAL CLOSED QUEUING-NETWORKS WITH SUBNETWORKS HAVING POPULATION CONSTRAINTS

We consider closed queueing networks with general service times and su bnetworks having population constraints. Each such subnetwork consists of a subset of stations of the original network. The population const raint of a subnetwork prescribes that the total number of customers th at can be simultaneously present inside the subnetwork is limited to a fixed value called the capacity of the subnetwork. A customer who wan ts to enter the subnetwork while it is full has to wait in an external queue. As soon as a customer leaves the subnetwork, the first-in-line customer is allowed to enter the subnetwork. We apply and compare two approximate techniques for analyzing such networks, namely the aggreg ation technique and Marie's method. We emphasize the similarities and differences between these two techniques. Finally, we compare their ac curacy.