Imt-2000wcdma Downlink Multipath, Pn Sequence Capture Technology Research

The direct-sequence (DS/SS) multiple access , also know as code-division access (DS-CDMA),has significant advantages in the areas of capacity, frequency planning, privacy, and resistance to multipath fading to cellular and personal communication system. It has been the important manner of multiple access in the 3rd generation mobile communication system.This paper investigates the key technology of the DS-CDMA system-psendonoise(PN) code acquisition technology. Various PN code acquisition scheme has been introduced here . Because the hybrid acquisition scheme (combines parallel search with serial search)based on the correlator provides the flexibility in the trade-off between the mean acquisition time and system complexity and is easy to implement, It抯 focus on the scheme here.On the other hand ,this paper analyzes the effect of multiple access inference (MAI) on the code acquisition performance for the multipath fading channels. The closed-form expressions of the detection and false-alarm probabilities and mean acquisition time are derived for the hybrid acquisition scheme with two fixed threshold.At last, this paper proposes a new method of multipath search to the 3rd generation mobile communication system: a hybrid acquisition scheme based on the correlator with two dwell adaptive decision threshold. The multipath searching and the two dwell adaptive decision threshold are the new idea of this paper.Computer simulation results have shown the good performance of the presented method in this paper. The real communication system is more complicated and has more uncertain factor than the simulated system .But this paper does some helpful researching on the multipath searching. In the future ,many work need to do for the real mobile communication system.