Abstract
The 3rd generation wideband CDMA (W-CDMA) systems support the relative higher and variable bit rate transmissions for applications with various quality-of-service (QoS) requirements. Code assignment and reassignment schemes in W-CDMA are essential, which aim to boost utilization of codes. In this thesis, a dynamic code assignment (DCA) scheme is proposed for traffics with various quality-of-service classes, i.e., conversational, streaming, interactive and background classes, introduced by Universal Mobile Telecommunication System (UMTS). For the proposed DCA scheme, the grouping mechanism statically partitions the entire code tree into two groups and each group serves traffics with various QoS requirements. Through the grouping mechanism, code assignments and reassignments are dynamically performed on new and released calls over each separated code group, respectively. The DCA for code assignments and reassignments are then investigated via the even-driven simulation. From the simulation results, the proposed DCA can reduce the new call blocking probability and thus improve the system utilization for W-CDMA.