Performance of prioritized call admission strategies in cellular CDMA systems with limited receiver processors

Abstract

Blocking handoff calls which results in the forced termination of ongoing call is significantly undesirable than blocking new call attempts. Thus, call admission policies that give a priority to handoff calls have been intensively studied. For reducing the probability of forced termination, priority has been given to handoff calls over newly originating calls by reserving a number of channels exclusively for handoffs, which is known as the guard channels. We define a new method of giving a priority to handoff calls by using different thresholds when admitting new calls and handoff calls respectively. This method is especially useful in code division multiple access (CDMA) systems, where the capacity is limited by the total level of interference from the connected mobiles, call attempts are blocked when the interference level reaches a predetermined threshold above the background noise level. We define the interference-based prioritized call admission control (IPCAC) and consider various prioritised call admission strategies for practical CDMA systems where receiver processors also limit the call-blocking performance: call admission only with GCP, IPCAC with and without GCP, respectively. The performances are numerically evaluated and compared for various system parameters. Conclusions are drawn regarding the usefulness of prioritizing strategies under various traffic conditions that are characterized by the traffic load and the mobile speed.