• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.8C
• /
• pp.742-753
• /
• 2005

In this paper, we propose a rapid and reliable signal acquisition scheme for UWB (Ultra Wide Band) systems in typical indoor wireless channels. The proposed scheme is a two-step search with different thresholds and search window applied to a single correlator, where each step utilizes the single-dwell search with the bit reversal. Simulation results in IEEE 802. I5 Task Group .3a UWB indoor wireless channel show that the proposed scheme for the LHWB signals can achieve significant reduction of the required mean acquisition time as compared to the conventional single-dwell bit reversal search and double-dwell bit reversal search with more complex structure employing two correlators for various threshold levels. In addition, it is also observed that the proposed scheme can achieve much faster and reliable signal acquisition in noisy environments.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.12C
• /
• pp.1623-1632
• /
• 2004

In this paper, we analyze the performance of linear search and bit reversal search algorithms based on the single-dwell serial search for rapid UWB (Ultra Wide Band) signal acquisition in typical indoor wireless channel environments. Simulation results according to bin spacing and frame interval in IEEE 802.15 Task Group 3a UWB indoor wireless channels show that bit reversal search algorithm achieves much smaller normalized mean acquisition time than linear search algorithm. In particular, it is found that the normalized mean acquisition time of the bit reversal search according to the range of searching termination interval closely matches the ideal case. In addition, we observe that the acquisition performance of bit reversal search algorithm becomes much better as bin spacing gets finer.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.12C
• /
• pp.1133-1143
• /
• 2005

In this paper, we propose an enhanced two-step search scheme for rapid and reliable signal acquisition in UWB systems under multipath channels. The proposed TSS-LS (Two-Step Search scheme with the Linear search based Second step) achieves rapid acquisition performance comparable to the conventional TSS-BS (Two-Step Search scheme with the Bit reversal search based Second step) already proposed by the authors, based on the single-dwell search with two-step thresholds and search windows. However, unlike the TSS-BS which employs the bit reversal search in the second step, the proposed TSS-LS utilizes the linear search in the second step to improve the reliability of signal acquisition. Simulation results with multipath channel models by IEEE 802.15.3a show that the two-step search schemes for the UWB signal acquisition can achieve sig nificant reduction of the required mean acquisition time as compared to general search schemes. In addition, we observe that the proposed TSS-LS achieves quite good bit error rate performance for large signal-to-noise ratios, which is favorably comparable to the case of ideal perfect timing.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.1
• /
• pp.42-48
• /
• 2002

In this paper, a decision method using multiple threshold values for PN code acquisition in Direct Sequence Code Division Multiple Access (DS-CDMA) systems is described. We apply this technique to the conventional double dwell serial search algorithm and analyze it in terms of mean code acquisition time. For the analysis, we present mathematical model of proposed algorithm and also perform the simulation under IMT-2000 channel models. Numerical results show that our proposed scheme outperforms the conventional one by 0.2 - 0.5 sec with respect to the mean code acquisition time because multiple threshold values mitigate the possible decline in search performance caused by the use of a single threshold.