Rapid acquisition for multiband UWB systems: CAZAC vs. Barker sequences

Ultra wideband (UWB) is a promising radio technology for networks delivering extremely high data rates at short ranges. Rapid acquisition is an important issue due to the high data rate employed in UWB systems. In multiband UWB, the available spectrum is divided into multiple bands and only certain bands are used for transmission at a time. With this arrangement however, acquisition has to be done on every band due to the different channel response on each band. An acquisition scheme suitable for multiband UWB is proposed, using a double-dwell structure with variable thresholds. A unique feature of the proposal is phase elimination, which exploits the inherent coded structure of the multiband UWB preamble. This paper presents a general comparison of barker and CAZAC sequences as candidates of the preamble, and the proposed system is simulated using these two sequences. The proposed system is able to achieve low acquisition errors with reduced number of correlation operations required.