Adaptive Double-Dwell Code Acquisition Scheme of PN Sequences Using Smart-Antenna and Automatic Censoring Techniques

An adaptive non-coherent smart-antennas double-dwell code acquisition scheme for code division multiple access (CDMA) communication systems is studied and analyzed in this work. A combination of adaptive thresholding based on constant false alarm rate algorithms and smart-antennas technique is considered. One of the most important problems of PN code acquisition for DS/SS-CDMA communication systems is the presence of multipath signals, which have a random structure. Accordingly, an adaptively varying threshold scheme using automatic censoring algorithm based on ordered data variability, namely the automatic censoring adaptive processor (ACAP) is considered to improve the system performance. The drawback of this algorithm is that a large processing time is required if the serial search code acquisition scheme is used. Hence, the double-dwell search-scheme is proposed to solve this problem. The performance of the proposed system is analyzed in frequency-selective Rayleigh fading channels. It is shown through simulation results that, the smart-antennas double-dwell acquisition scheme with the ACAP algorithm significantly outperforms the existing adaptive smart-antenna serial search single-dwell systems.