A New Serial Acquisition with Automatic Threshold Control for DS/SS Communications

Since the received signal levels in mobile communications are unknown and location-varying, acquisition scheme of pseudonoise (PN) sequence with fixed threshold cannot achieve the desired performance. This fixed threshold scheme may cause too many false alarms or result in low detection probability according to the threshold value selected. In this paper, we present adaptive acquisition schemes of PN sequences, which estimate the background power level, multiply it with threshold coefficient to keep the false alarms constant, and use it as a threshold. Performance analysis for single path situation shows that the mean level adaptive processor (MLAP) has better detection performance than the order statistics adaptive processor (OSAP). Simulation results for multipath situation show that OSAP has robustness while MLAP masks some multipath components.