Code acquisition for the DS-CDMA RAKE receiver in a multipath fading channel

This paper presents acquisition algorithm and an improved detection technique for the DS/CDMA (direct sequence code division multiple access) RAKE receiver in a multipath fading channel. DS/CDMA systems use the RAKE receiver to overcome signal fading due to multipath propagation. To maximize the performance improvement of the RAKE receiver, an accurate code acquisition is required for the RAKE branches. The algorithm is able to find the pseudonoise (PN) code delay estimates for the RAKE branches in a multipath fading channel. In this paper a numerical method and computer simulation have been developed to simulate the acquisition. The mean acquisition time is investigated as a performance measure of the system using the Monte Carlo method. And also in order to analyze the effect of the acquisition on the RAKE receiver this paper brings out the effect of integration time, Doppler frequency, processing gain and the number of users on the acquired code phase