Browsing by Author "Chen, YS"

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A channel effect prediction-based power control scheme using PRNN/ERLS for uplinks in DS-CDMA cellular mobile systems
(2006-01-01)
Chen, YS
;
Chang, CJ
;
Hsieh, YL
;
交大名義發表
;
National Chiao Tung University
This paper proposes a channel effect prediction-based power control scheme using pipeline recurrent neural network (PRNN)/extended recursive least squares (ERLS) for uplinks in direct sequence code division multiple access (DS-CDMA) cellular mobile systems. Conventional signal-to-interference (SIR) prediction-based power control schemes may incur prediction mistakes caused by the adjustment of transmission power. The proposed power control scheme purely tracks the variation of channel effect and, thus, can be immune to any power adjustment. Furthermore, it adopts the PRNN with ERLS for predicting the channel effect. Simulation results show that the channel effect prediction-based power control scheme using PRNN/ERLS achieves a 40% higher system capacity and a lower outage probability than the conventional SIR prediction-based power control scheme using grey prediction method (IEEE Trans. Veh. Technol., Vol. 49, No. 6, p. 2081, 2000).
A floating well method for exact capacitance-voltage measurement of nano technology
(2003-06-01)
Su, HD
;
Chiou, BS
;
Wu, SY
;
Chang, MH
;
Lee, KH
Small gate area with short gate length reduces the C-V distortion of ultrathin oxide devices, but results in high parasitic capacitance/total capacitance ratio. The floating well method can exclude the parasitic capacitance to obtain accurate inversion oxide thickness without using any dummy pattern. It is suitable for nano technology.
A neural-net based fuzzy connection admission controller for wireless ATM
(1997)
Chen, YS
;
Chang, CJ
;
Tzou, WY
;
Ren, FC
;
交大名義發表
A neural-net based fuzzy connection admission controller for a wireless ATM network is designed in this paper. it is a QoS-guaranteed controller, where QoSs of both air interface and ATM network are taken into consideration. Hence, for the neural fuzzy admission decision controller, we further design fuzzy capacity requirement estimator, fuzzy air interface performance estimator, and fuzzy system status estimator for reflecting the equivalent capacity required by the new call request, air interface performance, and the ATM network status, respectively. The simulation result shows that the neural fuzzy connection admission controller can gain high bandwidth utilization for wireless ATM networks.
A physical model for hole direct tunneling current in P+ poly-gate PMOSFETs with ultrathin gate oxides
(2000-11-01)
Yang, KN
;
Huang, HT
;
Chang, MC
;
Chu, CM
;
Chen, YS
A model of the hole direct tunneling gate current accounting for heavy and light hole's subbands in the quantized inversion layer is built explicitly. This model comprises four key physical parameters: inversion layer charge density, hole impact frequency on SiO2/Si interface, WKB transmission probability, and reflection correction factor. With the effective hole mass m(oxh) = 0.5m(o) for parabolic dispersion relationship in the oxide, experimental reproduction without any parameter adjustment is consistently achieved in p(+) poly-gate pMOSFETs with 1.23, 1.85, and 2.16 nm gate oxide thicknesses. The proposed model can thereby serve as a promising characterization means of direct tunnel oxides. In particular, it is calculated that the secondary subbands and beyond, although occupying few holes, indeed contribute substantially to the direct tunneling conduction due to effective lo,vcr barrier heights, and are prevailing over the first subbands for reducing oxide field down below 1 MV/cm.
A power control scheme with link gain prediction using PRNN/ERLS for DS-CDMA cellular mobile systems
(2003)
Hsieh, YL
;
Chang, CJ
;
Chen, YS
;
電信工程研究所
;
Institute of Communications Engineering
In this paper, a link gain prediction-based power control scheme is designed for DS-CDMA cellular mobile systems. The link gain prediction can help to remove the interference of the power control adjustment itself. The pipeline recurrent neural network (PRNN) with extended recursive least square (ERLS) is adopted for the prediction. This PRNN/ERLS predictor possesses infinite memory of past signals so that it can capture precisely the signal correlation and improve the delay compensation of power control. Simulation results show that the link gain prediction-based power control scheme using PRNN/ERLS has lower outage probability than the received SIR prediction-based power control scheme using grey prediction method [5] and improves the system capacity by an amount of 41.6%.
A Q-learning-based multi-rate transmission control scheme for RRC in WCDMA systems
(2002-01-01)
Ren, FC
;
Chang, CJ
;
Chen, YS
;
交大工研院聯合研發中心
;
NCTU/ITRI Joint Research Center
In this paper, a Q-learning-based multi-rate transmission control scheme (Q-MRTC) for radio resource control (RRC) in WCDMA systems is proposed. The RRC problem is modelled as a semi-Markov decision process (SMDP). And we successfully apply a real-time reinforcement learning algorithm, named Q-learning, to accurately estimate the transmission cost for the multi-rate transmission control. For the cost function approximation, we apply the feature extraction method to map the original state space into a more compact set which represents the resultant interference profile. Simulation results show that the Q MRTC can achieve higher system throughput and better users' satisfaction index, by an amount of 87% and 50%, respectively, than the interference-based multi-rate transmission control scheme, while keeping the QoS requirement.
A systematic design of protocol processors
(1996)
Chen, AY
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Chen, YS
;
Chang, RC
;
Wen, KA
;
交大名義發表
An innovative design methodology is proposed for protocol processors design. The protocol description is mapped to statecharts and statecharts are then mapped to a real-time operating system as well as microprocessors. The IS-54 protocol for cellular wireless communication mobile station is taken as the design example. And an efficient and easy-for-evaluation design environment is then constructed.
An editing system for working processes
(2001)
Chen, YS
;
Wang, FJ
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資訊工程學系
;
Department of Computer Science
Business processes are often complex and varying. Workflow technologies help people minimize errors and delays in the progress of a process within an enterprise. Within a workflow management system (WFMS), a process or even a project can be specified and interpreted to work directly. In this paper, we present an editing system and its two major components, PDE and FormDesigner, for the specification of a process. PDE is a graphical editor for constructing / modifying process definition. FormDesigner assumes the responsibility of integrating software components for building / modifying active application forms. With PDE and FormDesigner, a workflow application system can be constructed / modified rapidly and easily so that WFMS is allowed to run smoothly.
An on-demand, link-state, multi-path QoS routing in a wireless mobile ad-hoc network
(2004-01-01)
Chen, YS
;
Tseng, YC
;
Sheu, JP
;
Kuo, PH
;
資訊工程學系
The peer-to-peer multimedia applications have recently generated much interest in wireless network infrastructure with supporting the quality-of-service (QoS) communications. In this paper, we propose a new on-demand QoS routing, namely link-state multi-path QoS routing, protocol in a wireless mobile ad-hoc network (MANET). Our proposed scheme offers a bandwidth routing protocol for QoS support in a multihop mobile network. Our QoS routing protocol determines the end-to-end bandwidth calculation and bandwidth allocation at the destination. Our protocol collects link bandwidth information from source to destination in order to construct a network topology with the information of link bandwidth at the destination. To satisfy a given bandwidth requirement, the bandwidth calculation of the QoS route are determined at the destination to accurately determine the QoS uni-path or multi-path route depending on the status of network bandwidth. Our routing scheme may offer a multi-path route if a MANET with the insufficient network bandwidth, and provide a uni-path route if the network bandwidth is sufficient. The destination eventually determines the QoS multi-path routes and replies to the source host to perform the bandwidth reservation. Our routing scheme obviously improves the success rate of identifying a QoS route, and the simulation result demonstrates this improvement. (C) 2003 Elsevier B.V. All rights reserved.
Anti-control of chaos of single time scale brushless dc motors and chaos synchronization of different order systems
(2006-03-01)
Ge, ZM
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Chang, CM
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Chen, YS
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機械工程學系
;
Department of Mechanical Engineering
Anti-control of chaos of single time scale brushless dc motors (BLDCM) and chaos synchronization of different order systems are studied in this paper. By addition of an external nonlinear term, we can obtain anti-control of chaos. Then, by addition of the coupling terms, by the use of Lyapunov stability theorem and by the linearization of the error dynamics, chaos synchronization between a third-order BLDCM and a second-order Duffing system are presented. (c) 2005 Elsevier Ltd. All rights reserved.
Bi-mode breakdown test methodology of ultrathin oxide
(2003-12-01)
Su, HD
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Chiou, BS
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Ko, CY
;
Wu, SY
;
Chang, MH
The breakdown detections of ultrathin oxide (1.4-2 nm) using a fast voltage ramp have been studied. It was found that the breakdown voltage test of deep sub-micron technology requires the reduction of the gate area of test patterns and therefore the increase of the number of structures due to a large inversion gate current at a low electrical field (> 0. 1 A/cm(2) at 1 V) caused by the scaling down of oxide thickness. The gate current in accumulation mode is smaller than that in inversion mode by more than two orders of magnitude at a low applied voltage (1 V). The bi-mode model proposed in this paper applies a voltage stress in the inversion mode and detects failure in the accumulation mode to enhance the robustness of the breakdown test and reduce the possibility of pseudo breakdown failure. With the proposed method, a shorter test time with an increased test pattern area to improve the efficiency of the breakdown test of ultrathin oxide is achieved.
Blind identification of MIMO channels with periodic modulation
(2005)
Lin, CA
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Chen, YS
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電控工程研究所
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Institute of Electrical and Control Engineering
We propose a method for blind identification of MIMO FIR channels with periodic modulation. The method exploits linear relation between the covariance matrix of the received data and the "product matrices" of the channel. The proposed algorithm requires solving linear equations and computing eigenvalues and eigenvectors of a Hermitian matrix. We show that the identiflability condition depends on the modulating sequences alone and the method is robust with respect to channel order overestimation. A method for optimal selection of modulating sequences is proposed, which takes into account the effect of noise and the numerical error in estimating the covariance matrix of the received data. Simulations are used to demonstrate the performance of the proposed algorithm.
Chaos anticontrol and synchronization of three time scales brushless DC motor system
(2004-12-01)
Ge, ZM
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Cheng, JW
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Chen, YS
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機械工程學系
;
Department of Mechanical Engineering
Chaos anticontrol of three time scale brushless dc motors and chaos synchronization of different order systems are studied. Nondimensional dynamic equations of three time scale brushless DC motor system are presented. Using numerical results, such as phase diagram, bifurcation diagram, and Lyapunov exponent, periodic and chaotic motions can be observed. By adding constant term, periodic square wave, the periodic triangle wave, the periodic sawtooth wave, and kxx term, to achieve anticontrol of chaotic or periodic systems, it is found that more chaotic phenomena of the system can be observed. Then, by coupled terms and linearization of error dynamics, we obtain the partial synchronization of two different order systems, i.e. brushless DC motor system and rate gyroscope system. (C) 2004 Elsevier Ltd. All rights reserved.
Chaos synchronization and chaos anticontrol of a rotationally supported simple pendulum
(2004-03-01)
Ge, ZM
;
Yu, CY
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Chen, YS
;
機械工程學系
;
Department of Mechanical Engineering
Chaos synchronization and anticontrol of a rotationally supported simple pendulum was studied in this paper. Different kinds of coupling terms are used to synchronize the two identical chaotic systems with different initial conditions. An observed-based scheme is also used to achieve synchronization. The results are demonstrated by phase portrait, Lyapunov exponent, Poincare maps and synchronization time. Next, in order to analyze the transient behavior of the synchronized systems, Euclidean distance is used to plot a figure with coupling strength versus the distance. The chaotic signals are used to mask the message function in the secure communication system. Finally, anticontrol of chaos is achieved by adding constant term, periodic term, impulse term, time-delay term and adaptive control.
Chaos synchronization of a horizontal platform system
(2003-12-04)
Ge, ZM
;
Yu, TC
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Chen, YS
;
機械工程學系
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Department of Mechanical Engineering
Chaos and chaos synchronization of the horizontal platform system are studied in this paper. Because of the non-linear terms of the systems, the systems exhibit both regular and chaotic motions. By applying various numerical results, such as phase portraits, Poincare maps, time history and power spectrum analysis, the behaviors of the periodic and chaos synchronization are presented. The effects of the change of parameters in the system can be found in the bifurcation diagrams. Chaos synchronization of feedback methods in two coupled systems has been studied by Lyapunov exponent and coupling strength. Besides, phase effect of external excitations and the transient time in unidirectional synchronization also have been researched. (C) 2003 Elsevier Science Ltd. All rights reserved.
Chaos, chaos control and synchronization of the vibrometer system
(2004-09-01)
Ge, ZM
;
Lin, CC
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Chen, YS
;
機械工程學系
;
Department of Mechanical Engineering
The dynamic system of the vibrometer is shown to produce regular and chaotic behaviour as the parameters are varied. When the system is non-autonomous, the periodic and chaotic motions are obtained by numerical methods. Many effective methods have been used in chaos synchronization. It has been shown that chaos can be synchronized using special feedback control and that external excitations affect the synchronization.
Characteristics of oxide breakdown and related impact on device of ultrathin (2.2 nm) silicon dioxide
(2003-09-01)
Su, HD
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Chiou, BS
;
Wu, SY
;
Chang, MH
;
Lee, KH
The oxide breakdown characteristics of ultrathin oxide (2.2 nm) have been studied in this paper. Light emission microscopy (EMMI) analysis shows that each breakdown has a specific failure location with a random distribution. Gate leakage current increases for all soft breakdown events are similar. After soft breakdown, the I-V curve still shows the representative direct tunneling characteristics and can be fitted using a dual direct tunneling (DDT) model. Soft breakdown has no effect on the drain current of long-channel devices. Breakdown at the polyedge appears to be of the hard-breakdown mode and results in an abrupt increase in gate current. For short-channel devices, the polyedge is always within the damaged region of an oxide because the channel is shorter than the damaged region of the oxide. Hence, only hard breakdown resulting in permanent damage is observed in short-channel devices.
Compact efficient diode-pumped Nd : YVO4 Q-switched blue laser with intracavity frequency tripling
(2005-08-01)
Chen, YF
;
Chen, YS
;
Ou, TH
;
Su, KW
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電子物理學系
We demonstrate a compact efficient diode-pumped acousto-optically Q-switched intracavity-frequency-tripled Nd:YVO4 blue laser. The optimum polarization state is experimentally investigated to optimize the output performance. Greater than 280 mW of 447-nm average power at a repetition rate of 25 kHz was generated with a 15-W diode pump power. At 25 kHz, the pulse width is shorter than 15 ns and the peak power is higher than 800 W.
Critical point energy as a function of electric field determined by electroreflectance of surface-intrinsic-n(+) type doped GaAs
(2004-11-01)
Chen, YS
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Wu, KS
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Wang, DP
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Huang, KF
;
Huang, TC
Electroreflectance of surface-intrinsic-n(+) type doped GaAs has been measured over a various biased voltage. The spectra have exhibited many Franz-Keldysh oscillations (FKOs) above band gap energy E-g. The electric field F and critical point energy E-c can be determined from the slope and intercept of FKOs fitting. Hence, we can obtain E-c as a function of F. In most of previous works, E-c is taken as E-g. However, it was found that E-c increases with F in this work. In order to explain this, the gain of energy of electron and hole in F was discussed. (C) 2004 American Institute of Physics.
Diode-pumped Q-switched laser with intracavity sum frequency mixing in periodically poled KTP
(2004-07-01)
Chen, YF
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Chen, YS
;
Tsai, SW
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電子物理學系
;
光電工程學系
We report on a diode pumped Q-switched yellow-orange laser, with intracavity sum-frequency generation, in a periodically poled KTiOPO4 crystal in a diode-pumped Q-switched dual-wavelength laser at 1064 and 1342 nm. The conversion efficiency is measured as a function of crystal temperature, incident pump power, and pulse repetition rate. Under optimal phase-matching conditions, the highest yellow-orange average power was 610 mW at a pump power of 17 W.