Probabilistic framework and performance evaluation for prioritized call admission control in next generation networks

Next generation networks (NGN) are designed to support a wide range of applications with various service classes (SCs) guaranteeing the respective quality of service (QoS) levels. Since such networks are resource constrained, call admission control (CAC) is imperative to achieve the required QoS levels. In this paper, a new probabilistic framework for CAC schemes is proposed based on controlling each SC independently by admitting low priority SC calls with a variable imposed probability. The incorporation of such a probabilistic framework is considered under a bandwidth-centric approach named probabilistic bandwidth reservation scheme (PBRS). Though equal service times are usually assumed in the literature, the present analysis considers SCs of different service times. By employing Markov chain analysis to treat the independent SCs that correspond to different call specifications, analytical expressions for the call blocking probabilities (CBPs) are derived. The performance of the proposed CAC scheme is studied not only with regard to CBP but, also, taking into account the priorities assigned to different SCs as well as fairness among various SCs and total network throughput. The proposed probabilistic framework allows the dynamic control of network resources considering also priority assignment, fairness and throughput. Analytical results concerning delay tolerant (DT) and delay-non-tolerant (DNT) traffic have been obtained applying the proposed scheme. Moreover, the relevant simulations have verified the accuracy of the proposed analysis.