Detection techniques for code acquisition in direct-sequence spread-spectrum systems employing PN matched filters

This paper presents threshold detection techniques for direct sequence code acquisition employing psuedo-noise (PN) matched filters. The probabilities of detection and false alarm are derived as a measure of the system performance in both nonfading and nonselective Rician fading channels. For received PN codes with different SNR, the proposed acquisition schemes (serial and parallel) are able to detect a desired threshold in the search mode so that this value is utilized as a threshold for the verification mode. It is shown that the serial scheme achieves lower probability of false alarm than the acquisition scheme based on the Neyman-Nearson criterion, giving comparable performance in terms of the probability of detection. On the other hand, it its shown that the parallel scheme is able to provide a sub-optimal threshold value for a wide range of SNR such that the mean acquisition time is minimized.