Effect of non-uniform traffic distributions on performance of a cellular CDMA system

This paper presents a study of the effect of nonuniform user traffic distributions on the performance of a CDMA cellular system. While, there have been many studies showing the capacity gains of CDMA over narrowband TDMA systems, most of these studies assume a uniform distribution of the user population across the coverage area. When compared to the more general case of non-uniform user distributions, the uniform user distribution leads to lower multi-user interference and consequently higher system capacity. Hence, use of these models can lead to overestimation of system capacity. Three non-uniform user density models are developed and used to analyze the system's performance in typical CDMA implementation scenarios. The results indicate that intra-cell multi-user interference dominates the total interference levels in most cases. As expected cell splitting is shown to improve the system performance. The most significant improvements in performance with cell-splitting are seen for a Gaussian user density model (when compared to linear or exponential user density models). The results provide additional insight into the performance of CDMA systems, and are useful for the purposes of network planning and resource allocation.