Optimal search strategies for ultrawide bandwidth signal acquisition

The important task of acquiring a spread-spectrum signal in a reasonable amount of time prior to commencing communication can be quite challenging for a receiver, especially when the transmission bandwidth is large. This paper investigates search techniques that minimize and maximize the mean acquisition time (MAT), a widely used performance measure of an acquisition receiver. We prove that a fixed-step serial search, a form of non-consecutive serial search, achieves a near-optimal MAT. In addition, we prove that the conventional serial search, in which consecutive cells are tested serially, results in the maximum MAT. Since these results are valid for any signal-to-noise ratio value, any fading distribution, and any detail of the detection layer, the paper provides search strategies that acquisition receivers should employ and search strategies that acquisition receivers should avoid.