On acquisition of wideband direct-sequence spread spectrum signals

Very high rate packet data systems such as those based on wideband spread-spectrum (SS) signaling face an important challenge - achieving fast and reliable acquisition to minimize preamble overhead and optimize packet throughput. Such wideband modulation schemes undergo frequency selective fading, implying a very large number of resolved multipath components. Thus, the conventional analyses of serial search acquisition schemes based on simplifying assumptions that are valid in narrow(er) band systems (and are invalid for sufficiently wideband systems) need to be revamped. Also, there is a need to devise new schemes that exploit the presence of multipath components for faster acquisition over simple serial search. Our work provides novel contributions in both these aspects: we analyze serial and random search acquisition schemes and compare their performances in several multipath environments. It is shown that over many typical indoor channels, random search offers significantly lower mean acquisition times