Hybrid acquisition in DS/CDMA forward link

The evaluation of a hybrid acquisition performance has been considered for the pilot signal in the direct sequence code division multiple access (DS/CDMA) forward link. The hybrid acquisition is introduced by the combination of two schemes, parallel and serial acquisitions. The mean acquisition time of the proposed scheme is derived by considering both case 1 (the correct code-phase offsets are included in one subset) and case 2 (the correct code-phase offsets exist at the boundary of two subsets), which are caused by the distribution of correct code-phase offsets in the subset. Detection, false alarm, and miss probabilities are derived for the cases of multiple correct code-phase offsets and multipath Rayleigh fading channel. Results are provided for the acquisition performance with respect to design parameters such as postdetection integration length in search and verification modes, subset size, and number of I/Q noncoherent correlators. Also, comparison between the hybrid acquisition and the fully parallel acquisition is provided in terms of the minimum mean acquisition time.