Performance evaluation of orthogonal variable-spreading-factor code assignment schemes based on UMTS/IMT-2000 in W-CDMA

This paper compares the performance of the orthogonal-variable-spreading-factor (OVSF) code assignment schemes based on UMTS/IMT-2000 proposed so far, i.e., the conventional code assignment scheme (CONV), the dynamic code assignment scheme (DCA), and region division assignment scheme (RDA). It was shown that RDA gives better performance than DCA and CONV in terms of the packet dropping probability under heavy traffic conditions. In this paper, we make extensive performance comparisons among the three proposed OVSF code assignment schemes. We focus on two performance measures, i.e., the number of simultaneous voice conversations and the calculation time. The simulation results show that the calculation time of RDA is significantly lower than that of DCA. RDA can simultaneously handle much more voice sources than DCA.