Call Admission Control for Non-Standalone 5G Ultra-Dense Networks

In this letter, we propose new handoff schemes to reduce the interruption time that occurs during re-connection of an arriving mobile user moving from macrocell to small cell or from small cell to macrocell domains. A new call admission control function is developed to adjust thresholds during handoff request signaling. To perform the handoff operation, Markov chain technique is used to analyze the call blocking probability characteristic and subsequently to decide handoff approval for various subscriber requests. Numerical results show that the proposed admission control mechanism is able to minimize call blocking probability, without sacrificing resource utilization, and to reduce the number of service interruptions occurring during user re-connections.