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Ultrawide bandwidth serial-search multi-dwell acquisition-Part I: Asymptotic theory

The use of ultrawide bandwidth (UWB) signals requires highly accurate timing, and, hence, presents significant challenges from the standpoint of acquisition receiver design. Improving the acquisition performance is important, especially for time-critical applications that cannot tolerate long processing delay. This paper deals with the design and analysis of UWB rapid acquisition receivers. In particular, we consider serial-search strategies that employ a multi-dwell detector with optimal thresholds. Specific contributions include derivation of lower and upper bounds on the asymptotic mean acquisition times for both the conventional and the optimal serial search strategies. The bounds serve as ultimate performance limits of acquisition receivers that operate in high and low signal-to-noise ratio regimes. We propose a search strategy that is near-optimal in these asymptotic regimes. The results in this paper are valid for environments with arbitrary power dispersion profiles, provided that some mild assumptions about the channel and the receiver design are satisfied.