Browsing by Author "Wu, ML"

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A programmable pipelined digital differential matched filter for DSSS receiver
(2001-11-01)
Chiou, CH
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Huang, CW
;
Wen, KA
;
Wu, ML
;
電子工程學系及電子研究所
A programmable pipelined digital differential matched filter (PDMF) implemented for a direct sequence spread spectrum receiver is proposed in this paper. To reduce the power consumption, the architecture PDMF is based on the synchronization combined PN code phase acquisition algorithm (Huang et al., 1999). Compared with the conventional PN code phase acquisition algorithm, the theoretical analysis result indicates that the PDMF acquires both power efficient and preferable detection. Depending on different applications, programmability allows the PDMF to implement 3-tap, 5-tap, or 11-tap Barker codes with the same hardware but different precisions for each tap coefficient. For short tap Baker codes, the architecture could adopt more precision on each tap coefficient to resist the channel noise. Simulation results also show that there are fewer errors of high sample precision with the same tape.
Design of low-loss tapered waveguides using the telescope structure compensation
(2003-10-01)
Chang, CW
;
Wu, ML
;
Hsieh, WF
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光電工程學系
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Department of Photonics
A low-loss tapered waveguide is achieved by the telescope structure compensation. The configuration of this design is similar to the Galilean telescope based on the bulk geometrical optics. We numerically calculate the transmission efficiency in the use of the beam propagation method (BPM) and the finite-difference time-domain method. The BPM simulation results reveal that the normalized transmission efficiency is more than 95%, even if the tapered angle is as large as 10degrees.
Efficient pseudonoise code design for spread spectrum wireless communication systems
(2001-06-01)
Wu, ML
;
Wen, KA
;
Huang, CW
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Power and bandwidth efficient communication schemes are of major concerns in wireless communication systems. One kind of efficient pseudonoise code is proposed in this paper that provides combined power-bandwidth efficiency. A novel algorithm for verifying the power and bandwidth efficient properties of a pseudonoise code is proposed with systematic analysis on code parameters. Applications of the derived codes had been implemented on 802.11 DS/SS system, which performs 36% bandwidth reduction and 14% power consumption reduction. Several new pseudonoise codes with different code lengths are also proposed.
Low-power adaptive pseudo noise code acquisition for spread-spectrum systems
(2002-10-01)
Wu, ML
;
Wen, KA
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A novel pseudo noise code acquisition combined with the newly proposed adaptive sampling rate and threshold control (ASTC) algorithm is derived for low-power spread-spectrum systems with complementary metal-oxide-semiconductor implementations. Low-power performance can be achieved by reducing the sampling rate of the proposed system while maintaining the system performance. The sampling rate is dynamically updated due to the change of the channel noise level. Under the assumptions that the channel is additive white Gaussian noise slow-fading channel, up to 74.3% reduction in power consumption compared to the conventional fixed-sampling rate and fixed-threshold architecture is demonstrated with insignificant increase of system complexity. The proposed architecture can be applied to the design of low-power and controllable-performance spread-spectrum communication systems.
Synchronization combined PN code phase acquisition algorithm (SCA) for DSSS receiver
(1999)
Huang, CW
;
Wen, KA
;
Wu, ML
;
電機學院
;
College of Electrical and Computer Engineering
A new algorithm for PN code phase acquisition, synchronization combined PN code phase acquisition algorithm (SCA) is proposed in tills paper. Compared with the conventional PN code phase acquisition algorithm, SCA has a higher detection probability and a lower false alarm rate. The simulation of power efficiency was done with a 3-bit PN code phase synchronizer and the result also shows that power efficiency of SCA is prefer to that of the conventional PN code phase acquisition algorithm.
The Optimized Threshold Decision of pseudo noise code acquisition in spread spectrum communication
(2000-11-01)
Wu, ML
;
Wen, KA
;
Chen, CS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, the authors derived the distributions of the probability of detection and of false alarm in function of the decision threshold. An Optimized Threshold Decision (OTD) algorithm was proposed to decide the optimal threshold for reaching the best system performance in a given known channel noise. By applying this OTD algorithm, the multiple access capacity can thus be maximized.