Cell search performance analysis for W-CDMA

Due to the main advantages of spread spectrum techniques such as good performance in frequency selective channels, high data rate and capacity flexibility, W–CDMA has been selected as transmission technology for 3G cellular systems. With respect to the overall system performance, the initial synchronization of the locally generated PN sequence with the received signal is a critical task. In order to simplify the process of downlink signal acquisition, which is also referred to as cell search, a three step approach is employed for the FDD mode. In this paper an analytic approach for performance analysis of W–CDMA cell search in flat Rayleigh fading channels is presented. By deriving the probability density functions (pdf) of the test hypotheses, the stage transition probabilities and the important performance measure mean acquisition time are determined. Based on these results the impact of system and algorithm parameters on the cell search performance is investigated. The reliability of the presented approach is confirmed by Monte Carlo simulations.