Browsing by Author "Lee, Y"

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A robust adaptive generalized sidelobe canceller with decision feedback
(2005-11-01)
Lee, Y
;
Wu, WR
;
電信工程研究所
;
Institute of Communications Engineering
Conventional generalized sidelobe canceller (GSC) is sensitive to a mismatch between the estimated and actual direction of arrival (DOA) of the desired signal. Such a mismatch induces signal cancellation in the GSC, and it severely degrades the beamforming performance. In this paper, we propose a new decision feedback (DF) technique to increase the robustness against the DOA mismatch. Our new scheme introduces a blind equalizer and a feedback filter in the GSC structure. We first derive Wiener solutions for the DF-GSC with perfectly matched and mismatched DOA and show that the problem of signal cancellation can be avoided. Then, we consider the adaptive GSC implementation in which the least-mean-square (LMS) algorithm is used for weight adaptation. In addition to the improved robustness, the proposed scheme also remedies the slow convergence problem inherent in the conventional adaptive GSC structure. The convergence behavior of the LMS-based DF-GSC is fully analyzed and the analytic signal-to-interference-plus-noise ratio (SINR) is also derived. Finally, simulation results demonstrate that while the proposed structure can considerably enhance the overall performance, it has greatly improved robustness as compared to other existing robust adaptive beamformers.
Robustness analysis of a decision feedback generalized sidelobe canceller
(2005)
Lee, Y
;
Wu, WR
;
電信工程研究所
;
Institute of Communications Engineering
Conventional generalized sidelobe canceller (GSC) is sensitive to a mismatch between the estimated and actual direction of arrival (DOA) of the desired signal. Such a mismatch induces signal cancellation in the GSC. Recently, a new decision feedback (DF) technique has been proposed to improve the adaptive GSC performance. In this paper, we analyze the robustness of this algorithm. The Wiener solution for the DF-GSC in mismatch is derived and the result shows that the problem of signal cancellation can be avoided. Simulation demonstrates that the DF-GSC has greatly improved robustness as compared to the conventional GSC.
Tablet PC as a mobile PACS terminal using wireless LAN
(2003)
Tsao, BH
;
Ching, YT
;
Lee, WC
;
Chen, S
;
Chang, C
A PACS mobile terminal has applications in ward round, emergency room and remote teleradiology consultation. Personal Digital Assistants (PDAs) have the highest mobility and are used for many medical applications. However, their roles are limited in the field of radiology due to small screen size. In this study, we built a wireless PACS terminal using a hand-held tablet-PC. A tablet PC (X-pilot, LEO systems, Taiwan) running the WinCE operating system was used as our mobile PACS terminal. This device is equipped with 800x600 resolution 10.4 inch TFT monitor. The network connection between the tablet PC and the server was linked via wireless LAN (IEEE 802.11b).