Browsing by Author "Yang, HL"

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A novel adaptive code acquisition using antenna array for DS/CDMA systems
(2005)
Yang, HL
;
Wu, WR
;
電信工程研究所
;
Institute of Communications Engineering
This paper proposes a novel code acquisition scheme employing an adaptive beamformer and an adaptive temporal filter. Conventional code acquisition with beamforming requires a code-phase testing procedure which can be time-consuming. The proposed scheme simultaneously performs beamforming and code acquisition and the acquisition time can be much shorter than conventional approaches. Using the least mean square (LMS) adaptive algorithm, we are able to obtain a simple yet robust acquisition scheme. We also perform theoretical analysis which includes derivations of the minimum mean-squared error (MSE), the excess MSE, and the beamformer output signal-to-interference-plus-noise ratio (SINR). Simulation results verify that the proposed scheme has satisfactory performance and the derived theoretical results are accurate.
Multirate adaptive filtering for DS/CDMA code acquisition
(2003)
Yang, HL
;
Wu, WR
;
電信工程研究所
;
Institute of Communications Engineering
Code acquisition in DS/CDMA systems is usually conducted using a correlator. However, in a multiuser access interference (MAI) environment, its performance is seriously degraded. The adaptive filtering scheme has been proposed to overcome this problem. Although this approach is effective, it requires high computational complexity. This paper proposes a multirate adaptive filtering scheme to alleviate this problem. The proposed scheme uses two adaptive filters operated in different rates. Due to downsampling operations, the computational complexity of the adaptive filters can be effectively reduced. We also theoretically analyze the mean acquisition time and the acquisition error probability. Simulations show that while the proposed scheme can have better performance, its computational complexity is only half of the conventional adaptive filtering method.
The study of the sublimable six-coordinated aluminum quinolate with sulfonamide substitutents
(2004-10-21)
Cheng, JA
;
Chen, CH
;
Yang, HL
;
應用化學系
;
友訊交大聯合研發中心
A sublimationable blue-green host materials based on tris(8-hydroxyquinolato)aluminum, meridional tris(5-N-ethylanilinesulfonamide-8-quinolato) aluminum, mer-Al(Saq)(3), was investigated and characterized by thermogravimetric analysis (TGA) and H-1 nuclear magnetic resonance (NMR). Via molecular engineering, the sublimation enthalpy of mer-Al(Saq)(3) can be adjusted by introducing the N-ethylanilinesulfonamide substitutent. Its electroluminescence (EL) was also characterized by the device architecture of glass/ITO (200 nm)/CuPc (15 nm)/NPB (60 nm)/mer-Al(Saq)(3) (55 nm)/LiF (1 nm)/Al (200 nm). It shows a blue-green spectrum with blue-green of 1931 CIEx,y(0.25, 0.39). Our experiments revealed that the Al-N bond order might not be the major issue in sublimation process. (C) 2004 Elsevier B.V. All rights reserved.