The robustness of blocking probability in a loss system with repeated customers

In this paper, we analyze and synthesize a multi-server loss system with repeated customers, arising out of NTT DoCoMo-developed telecommunication networks. We first provide the numerical solution for a Markovian model with exponential retrial intervals. Applying Little’s formula, we derive the main system performance measures (blocking probability and mean waiting time) for general non-Markovian models. We compare the numerical and simulated results for the Markovian model, in order to check the accuracy of the simulations. Via performing extensive simulations for non-Markovian (non-exponential retrial intervals) models, we find robustness in the blocking probability and the mean waiting time, that is, the performance measures are shown to be insensitive to the retrial intervals distribution except for the mean.