Direct sequence spread spectrum parallel acquisition in a fading mobile channel

Abstract

The acquisition performance of a direct-sequence spread-spectrum system is investigated in a fading mobile environment. A parallel acquisition scheme is applied to make up for the effect of the fading environment on key parameters such as the probability of detection, the probability of false alarm, and the mean acquisition time. An expression for the mean acquisition time is derived in terms of detection, false alarm, and missing probabilities. These probability expressions are derived in both a nonfading and fast-fading AWGN (additive white Gaussian noise) channels, and the mean acquisition time is shown for nonfading, slow-fading, and fast-fading channels. It is shown that in a nonfading channel, the designer should choose the MF (matched filter) length as large as practically possible and then cover the rest of the uncertainty region with parallel MFs. The same applies for the slow-fading channel. In fast-fading channels the contrary is the right choice; for better performance the designer needs to increase parallelism at the cost of MF length. >