Performance Evaluation of Two-Link Multirate Loss Models with Restricted Accessibility

We consider a two-link communication system with restricted accessibility that services Poisson arriving calls of many service-classes and propose a multirate teletraffic loss model for its analysis. In a restricted accessibility system, call blocking occurs even if available resources do exist at the time of a call’s arrival. In the two-link system under consideration, each link has two thresholds (offloading and support) which express the in-service calls in a link. The offloading threshold represents the point from which a link offloads calls. The support threshold (which is lower than the offloading threshold) defines the point up to which a link supports offloaded calls. The two-link system with restricted accessibility is modeled as a loss system whose steady state probabilities do not have a product form solution. However, approximate formulas for the determination of call blocking probabilities are proposed. In addition, we also provide a corresponding analysis related to the case of quasi-random traffic (i.e. traffic generated by a finite number of users). The accuracy of all formulas is verified through simulation and is found to be quite satisfactory.