This paper investigates the impact of chip duty factor (DF) in DS-UWB system with Rake receiver over AWGN and UWB indoor multipath environment corresponding to system parameters such as spreading bandwidth and chip length. Manipulating DF in DS-UWB system offers several advantages over multipath channel and thus, capable of improving system performance for better quality of communication. Although employing lower DF generally improves performance, in some exceptional cases on the other hand, degradation can be observed despite decreasing DF. Therefore, the objective of this paper is to clarify the relationship between DF and DS-UWB system performance. We discovered that with constant processing gain and spreading bandwidth, performance improvement can be observed at DF lower than 0.17. Additionally, with spreading bandwidth as tradeoff parameter, significant performance improvement can only be observed below DF of 0.85.

We propose a rapid and reliable signal acquisition scheme for UWB (Ultra Wide Band) systems in indoor wireless environments. The proposed scheme is a two-step search with different thresholds and search windows, where each step utilizes the single-dwell search with the bit reversal. Simulation results show that the proposed scheme for the UWB signals can achieve significant reduction of the required mean acquisition time as compared to other schemes including general double-dwell search scheme for various threshold levels. Furthermore, it is also observed that the proposed scheme can achieve much faster and reliable signal acquisition as the first threshold is larger in noisy environments.