A Dynamic Reservation and Call Admission Control Policy with HMM for Multimedia Cellular Networks

Abstract

The multimedia services are getting to become the major trend in next-generation cellular networks. Call admission control (CAC) plays the key role for guaranteeing the quality of service (QoS) in cellular networks. The goal which keeps both the call dropping probability (CDP) and call blocking probability (CBP) as low as possible is more difficult owing to the user indeterminate mobility. In this paper, the Hidden Markov Models (HMM) concept which is suitable for solving a dynamic situation is introduced and applied to the call admission control policy. The prediction of user mobility can be modeled and resolved as a decoding problem for the HMM. According to the prediction result, the proposed CAC method can reserve appropriate bandwidths for a handoff call beforehand, thus the call dropping probability is almost the same as the traditional guard channel policies that can keep lower CDP than unpredicted ones, moreover, the call blocking probability is also lower than the traditional guard channel policies since the proposed method can reserve the suitable bandwidths in the appropriate cells but not reserve a stationary ones which are always adopted by traditional CAC methods. Therefore, the proposed method can not only satisfy both CDP and CBP issues, but also improve the system utilization.