Call admission control scheme using borrowable guard channels and prioritizing fresh calls retrials in small cell networks

Recent trends in mobile cellular networks turn towards deployment of Small Cell Networks (SCNs), where, the cell size gets smaller, and thus the number of subscribers served in a cell will be relatively smaller, such that traffic models with a finite source of subscribers should be considered. Smaller cells cause the mobile subscribers to cross several cells during an ongoing conversation resulting in frequent handovers. Most of works dealing with Call Admission Control (CAC) problems based on guard channels scheme in cellular mobile networks consider models without retrials (reapeted calls phenomenon). However, almost all existing works which take into account retrial consider an infinite population cell resulting in multi-servers retrial queueing model, for which the analytical solution is not available. In this paper, we propose to use the Generalized Stochastic Petri Nets (GSPNs) formalism as a novel alternative to investigate a new CAC strategy with retrial policy of fresh and handover calls generated by a finite population of subscribers, based on prioritization of retrial calls and adopting a guard channels borrowing concept, operating in SCNs. Performance evaluation shows that our approach is more efficient compared to basic guard channel scheme with better blocking probability, especially for low to medium handover calls rates.