Browsing by Author "Chiou, CH"

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3DPAC Video Codec Transmission over Internet with QoS Provision
(2000)
Wen, KA
;
Chiou, CH
;
Chen, AY
;
Lin, CH
;
Lin, JL
In this work, a VOD-like network application especially for wireless LAN and low bit rate Internet transmission. With the derivation of the software platform, Three-dimensional Polynomial Approximation Coding (3DPAC) video compression algorithm is employed and some TCP/IP network operation is driven. A simple experimental video transmission platform over TCP/IP is constructed to investigate the features for guarantee of quality of service development of this video compression and transmission system, and two excellent features, fidelity and agility of 3DPAC for QoS development are discovered.
A programmable pipelined digital differential matched filter for DSSS receiver
(2001-11-01)
Chiou, CH
;
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.
Effect of annealing on low-threshold-current large-wavelength InGaAs quantum well vertical-cavity laser
(2006-02-01)
Chen, IL
;
Hsu, WC
;
Kuo, HC
;
Sung, CP
;
Chiou, CH
An emission wavelength record emission wavelength of 1245 nm in double InGaAs/GaAs quantum wells without a strain-compensated barrier is obtained by metalorganic chemical vapor deposition (MOCVD). The effect of annealing on highly strained InGaAs quantum wells is analyzed using phtoluminanescence spectra. By comparing devices p-type distributed Bragg reflector (p-DBR) growth temperatures, the preliminary results indicate that a device with a low p-DBR growth temperature of 670 degrees C exhibits a low threshold current and a high light output power. A threshold current of 6.7 mA in an InGaAs vertical-cavity surface emitting laser (VCSEL) in CW operation is realized with an emission spectrum up to 1.26 mu m.
Growth of highly strained RnGaAs quantum wells by metalorganic chemical vapor deposition with application to vertical-cavity surface-emitting laser
(2006-01-01)
Chen, IL
;
Hsu, WC
;
Lee, TD
;
Kuo, HC
;
Su, KH
A series of highly strained InGaAs quantum wells (QWs) with GaAs barriers emitting at wavelength longer than 1.2 mu m are grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). The optimized windows of the V/III ratio of the InGaAs layer and the growth rate of the barrier are first investigated on thease highly strained QWs. By an appropriate choice of the growth conditions, we extend the room-temperature photoluminescence (PL) wavelength of InGaAs QWs to 1245 nm, which corresponds to an indium content of 42%. A GaAs-based InGaAs vertical-cavity surface-emitting laser (VCSEL) at an emission wavelength of 1.28 mu m with a large detuning of 90 nm has been realized by the use of highly strained InGaAs QWs.
Low-threshold-current-density, long-wavelength, highly strained InGaAs laser grown by metalorganic chemical vapor deposition
(2005-10-01)
Chen, IL
;
Hsu, WC
;
Kuo, HC
;
Yu, HC
;
Sung, CP
A long-emission-wavelength laser with multiple InGaAs/GaAs quantum wells without a strain-compensated barrier was grown by metalorganic chemical vapor deposition (MOCVD). InGaAs quantum well (QW) broad-area laser diodes with an emission wavelength of up to 1214 nm were realized. A measured room-temperature threshold current density of only 173 A/cm(2) for a 2-mm-cavity device and a transparency current density of 66 A/cm(2) were obtained. The internal quantum efficiency and laser cavity loss were 67% and 6 cm(-1), respectively.