Performance Evaluation of CAC Schemes for Multi-service Traffic Environment in 3G Networks

The ever-growing mobile market and the number of services offered by the network providers, which are increasing with every passing day, has reinforced the need for optimized CAC schemes. The introduction of Code Division Multiple Access (CDMA) has resulted in extensive reuse of frequency and therefore the birth of microcells has increased the number of handovers especially in metropolitan cities. Consequently further stress is exerted on existing CAC schemes to maintain the Quality of Service (QoS). In this paper we present new CAC algorithms based on dynamic allocation of channels to multiple input traffic streams. In this context two CAC schemes are proposed; IPG (Independent DT Queue priority, Pre-emptable DS priority, Guard Channel priority) and ITPG (Independent DT Queue priority, Timeout handover DS queuing Priority, Pre-emptable DS priority, Guard Channel priority). This scheme provides differentiated admission to various delay sensitive (DS) and delay tolerant (DT) traffic streams for both handover request (HOR) and new call request (NCR) according to current load intensity. The scheme provides an effective pre-emption priority in order to decreases forced handover failure probability. Service nature and customer behavior was considered to lay down the different levels of priorities that were assigned at different stages of the CAC scheme in order to achieve optimal QoS for urban area (metropolitan) cell. The simulation results demonstrate the improved QoS under various traffic scenarios.