Low-complexity schemes for UWB localization over indoor wireless channels.
Date of Issue2008
School of Electrical and Electronic Engineering
This research focuses on low complexity schemes for ultra wideband (UWB) localization applications over indoor wireless channels. The existing low complexity ranging algorithms detect the direct path (DP) by obtaining the leading edge of the correlation of the received signal and the local template or the energy within a short observation window, which crosses a certain specified threshold. These schemes, however, have common weaknesses that their performance is sensitive to the threshold setting. In this thesis, we propose an improved direct path detection scheme in indoor wireless channels. According to the power-delay profile of the impulse response of indoor wireless channels, several paths of the received signal may be closely spaced together as a cluster. It indicates that even if the DP signal is relatively weak, we can expect considerable energy will be received in the next several nanoseconds. Hence a double-threshold DP detection scheme of the amplitude and the energy of a relatively long observation window nearby will increase the robustness of the DP detection performance. The settings of the threshold values will be studied by simulations. To improve the accuracy of locating a mobile subscriber (MS) in the common office environment, a new algorithm is also proposed to distinguish between the the direct path-anchor points (DP-APs) and the not-direct path-anchor points (NDP-APs). In wireless communication systems over mobile outdoor wireless channels, the DP-APs and the NDP-APs are distinguished by measuring the standard deviation of the estimated channel parameters. That technique may not work properly for the indoor wireless channel, where the channel may remain static and no deviation can be observed for a relatively long time when nothing is moving in the local area.
DRNTU::Engineering::Electrical and electronic engineering::Wireless communication systems