Steady-State Performability Analysis of Call Admission Control in Cellular Mobile Networks

In this paper we propose a performability model of multiclass Call Admission Control (CAC) in cellular mobile networks. A performability model is a combination between availability model and performance model. A pure performance model, by ignoring failure and recovery, overestimates the performance measures of the considered system. On the other hand, a pure availability model is too conservative since performance considerations are not taken into account. We extend a previous work by proposing a composite model which considers performance changes associated with failure and recovery of radio channels in a CAC schema. We use the probabilistic model checking to perform the analysis of the performability model that we propose in this work. We first construct a composite multidimensional Continuous Time Markov Chain (CTMC) of the considered CAC schema containing both performance and failure-recovery events. Then we specify Quality of Service (QoS) requirements through the CTMC using the Continuous Stochastic Logic (CSL). Finally, we quantify the steady-state performability measures by checking CSL formulas using the PRISM model checker.