A Distributed Call Admission Control and Network Selection Scheme for Hybrid CDMA-OFDMA Networks

Efficient network selection and call admission control (CAC) strategies are the key components of the next generation heterogeneous wireless networks (HWN). In this paper, we propose a distributed uplink call admission control and network selection scheme for hybrid CDMA-OFDMA networks, which aims to efficiently utilize the overall radio resource of the HWN, on condition that the incoming call blocking probability and the ongoing call dropping probability are both within the acceptable ranges. When a new call arrives, based on the information obtained from the resource management modules of the two radio access networks (RANs), the process of network load estimation can be implemented in the corresponding mobile terminal (MT) through power estimation: 1) estimation of the required transmit power from the MT if it is admitted to either RAN; 2) estimation of the total uplink power consumptions in the two RANs after admitting the incoming call. Accordingly, CAC decisions can be made distributedly in the MT by comparing the total uplink power consumptions with the predetermined uplink power thresholds of the corresponding RANs. If the incoming call can be admitted by both RANs, the estimated terminal transmit powers in the two RANs are compared, and the RAN requiring less transmit power from the MT is selected as the target network. Simulation results indicate that our scheme is practical and effective in achieving high resource utilization with low probability of overload.