Analysis of Queuing based Call Admission Control Scheme in CDMA Cellular Network for Variation in Mobility and Soft Handoff Threshold

In CDMA cellular system, the coverage area of the cell is greatly influenced by soft handoff process. The variation in soft handoff coverage area can be taken as the parameter influencing the performance parameters of the CDMA cellular system. In this paper, an analytical model is developed and analyzed for the concerned target cell in CDMA cellular network. The model proposed in this paper is based on priority reservation for handoff calls along with call queuing scheme for new as well as handoff calls. Separate queues are considered for both new as well as handoff calls. Two dimensional Markov birth-death process is used for modeling the problem. The handoff queue capacity is considered as function of soft handoff coverage area which depends on the two soft handoff threshold parameters T_ADD and T_DROP. Considering fixed cell radius, variation in soft handoff coverage area also varies the normal area for new calls. It is seen that change in normal cell area is inversely proportional to soft handoff coverage area. The effect of this variation which leads to change in handoff call queue capacity along with mobility of mobile user is analyzed for variation in network performance parameters new call blocking probability, handoff request blocking probability, new and handoff call time out probabilities and forced termination probability for handoff request Increase in handoff call queue capacity effectively decreases handoff request blocking probability but leads to increment of new call blocking probability.