Quality of service estimation for soft handoff region ratio and call admission control in CDMA cellular systems

In the operational stage of code division multiple access (CDMA) systems, the soft handoff region ratio (SHRR) is among the important parameters that guarantee the quality of service (QoS) and resource allocation. This paper analytically investigates the effects of the SHRR on QoS. In doing so, we simultaneously take into account the capacity increasing factor and traffic load variation. For this purpose, we propose a new traffic load estimation model using a semi-Markov chain in order to consider the call arrivals influenced by the SHRR under general resident time condition. We also present the calculation algorithm of the QoS measures such as the new call blocking probability (NBP) and forced termination probability (FTP) by applying the proposed model to the prioritized call admission control (CAC). The numerical result illustrates the effects of various soft handoff system parameters. Likewise, it shows that the value of SHRR has a significant impact of the QoS under the normal propagation conditions. Sensitivity analysis is also performed to show the effect of exponential cell resident time assumption. The proposed modeling is expected to provide a practical guide to improve the QoS of CDMA soft handoff systems.