Browsing by Author "Huang, YL"

Now showing 1 - 14 of 14

A fully digital noncoherent and coherent GMSK receiver architecture with joint symbol timing error and frequency offset estimation
(2000-05-01)
Huang, YL
;
Fan, KD
;
Huang, CC
;
電信工程研究所
;
Institute of Communications Engineering
We propose a fully digital noncoherent and coherent Gaussian minimum shift keying (GMSK) receiver architecture with joint frequency offset compensation and symbol timing recovery in this paper. Carrier phase offset ran be estimated if the coherent demodulation mode is adopted. The converted base-band complex signal is first frequency discriminated and then passed through a digital filter which performs a fast Fourier transform (FFT), The frequency offset can be estimated from the de component of the FPT, and the symbol timing error can be estimated from the phase angle of the FFT at a specified frequency which is equal to an integral multiple of half the bit rate. These two estimated parameters are then used for frequency offset compensation and symbol timing recovery during a preamble period. Coarse carrier phase can be estimated by averaging sampled in-phase and quadrature-phase signals and finding its phase angle within the preamble period after carrier frequency offset is estimated and compensated. The bit error rate (BER) performance of this GMSK receiver architecture is assessed for an additive white Gaussian noise (AWGN) channel by computer simulation.
A generic electronic payment model supporting multiple merchant transactions
(2000)
Huang, YL
;
Shieh, SP
;
Ho, FS
;
資訊工程學系
;
Department of Computer Science
This paper presents a generic electronic payment model which is intended for a multi-merchant transaction, in which more than one merchant (the retailer, multiple resellers and content providers) are involved in the distribution of electronic contents. With our payment model, every involved merchant will be notified to verify the license information of a content on the settlement day before the customer actually pays for his purchase. Thus, piracy can be discouraged, intellectual property rights of electronic contents can be protected. Each of the involved merchants can obtain his own deserved share of the customer's payment in accordance with their union agreement on this content. As examples to demonstrate the applications of our generic payment model, two well-known payment systems are enhanced herein, based on our payment model.
A low TF GMSK modem architecture with joint symbol timing recovery and frequency offset compensation
(1996)
Huang, YL
;
Huang, CC
;
交大名義發表
;
電信工程研究所
;
National Chiao Tung University
This paper records our work in developing a GMSK modem with joint symbol timing recovery and frequency offset compensation capability. The received RF signal is first down converted to a low IE and then converted to complex baseband by a digital complex sampler. This baseband signal is then frequency discriminated and passed through a digital filter which in fact performs a Fast Fourier Transform (FFT). In other words, we apply an FFT algorithm on the frequency discriminated baseband signal in order to estimate symbol timing error and frequency offset simultaneously. The frequency offset can be estimated from the DC component of the FFT and the symbol timing error can be estimated from the phase angle of the FFT at a specified frequency which is equal to an integral multiple of half the bit rate. These two estimated parameters are then used for symbol timing recovery and frequency offset compensation. The Bit Error Rate (BER) performance of our GMSK receiver architecture is assessed for an AWGN channel by computer simulation.
An efficient authentication protocol for mobile networks
(1999-07-01)
Shieh, SP
;
Ho, FS
;
Huang, YL
;
資訊工程學系
;
Department of Computer Science
Many existing authentication protocols supporting inter-domain authentication on the Internet require their clients to communicate with every involved key distribution center (KDC) directly. This is inefficient and costly when the client side is a wireless mobile unit, for wireless transmission has relatively lower bandwidth, and a mobile unit is battery powered. In this paper, we present a mobile authentication protocol which only needs seven messages for inter-domain initial authentication regardless of the number of hops transited between the visited and home domains; four messages for subsequent authentication when the mobile user requests a different service provided by the visited domain; and two messages when the same service is requested again. With the enhanced version of BAN logic we propose, it is proved that our protocol can achieve more goals of authentication than those required by the original BAN logic.
Analysis of acidic herbicides in water using a toroidal coil CCC
(2003)
Huang, YL
;
Yu, T
;
應用化學系
;
Department of Applied Chemistry
A newly developed compact toroidal coil centrifuge chromatograph (TCCC) has been proven to be able to achieve high-resolution counter-current chromatography (CCC) separations. The potential of this devise is studied for analytical applications. The TCCC was used for the analysis of acidic herbicides in order to reduce the interference due to humic substances. Aqueous samples were pretreated with solid-phase extraction (SPE) and eluted with the lower phase of an n-hexane-ethyl acetate-water (15: 7: 20, v/v/v) solvent system. Because the humic substances were more hydrophilic than the herbicides, they were eluted first and separated from the herbicides. Although four herbicides were well resolved,. quantification of compound 2,4-dichloro-phenoxyacetic acid was, to some extent affected by the tailing signal of humic substances. Samples of analytes of 20 mug/L spiked in deionized water containing 6 and 12 mg/L humic acid, and in lake water, were analyzed. Mean recoveries ranged between 66 and 96%, with RSDs between 2 and 11%. While CCC has been known as a preparative chromatographic technique, the potential of using a TCCC device for quantitative analysis under complex matrices is demonstrated.
Dispatching in semiconductor fabs with machine-dedication features
(2006-04-01)
Wu, MC
;
Huang, YL
;
Chang, YC
;
Yang, KF
;
工業工程與管理學系
This research develops dispatching algorithms for a fab with machine-dedication characteristics. Machine-dedication, a new feature in a modern fab, has not been addressed in previous studies of dispatching. Three performance indices, including hit rate, mean cycle time, and throughput are of concern in dispatching. This research develops an algorithm, called LB-SA, based on a proposed simplification model of the process route. The line balance (LB) component aims to smooth the flow rate of the process route; and the starvation avoidance (SA) component aims to ensure that the bottleneck machine is not "starving" and has enough work-in-progress (WIP) to process all the time. Thirty dispatching algorithms, including the LB-SA algorithm, are compared by simulation. The LB-SA algorithm outperforms the other 29 algorithms both in terms of hit rate and mean cycle time, and is only slightly less than the best benchmark in throughput. Of the 29 other algorithms, one algorithm, called CR-SA, also performs very well. These two algorithms are both recommended for fabs with machine-dedication feature.
Efficient key distribution schemes for secure media delivery in pay-TV systems
(2004-10-01)
Huang, YL
;
Shieh, S
;
Ho, FS
;
Wang, JC
;
資訊工程學系
To provide secure media delivery in pay-TV systems, a large number of messages are exchanged for key updates in the conventional key distribution schemes. This is inefficient and costly when the client side (set-top box) uses a smart card with limited computing power. In this paper, we present three key distribution schemes for channel protection and secure media delivery in pay-TV systems. With the proposed schemes, encryption keys of the subscribed programs can be efficiently and securely distributed to the authorized subscribers. Only one message is needed to renew key in the key distribution schemes for subscription channel protection. In addition, we use simpler computation functions, including one-way hash function and exclusive-OR operation, for key updates to reduce the computation cost. With our key distribution schemes, only authorized subscribers can watch the subscribed programs correctly. Unauthorized subscribers have no information to retrieve the correct programs over the networks. Thus, service providers can charge their subscribers according to their subscriptions, and the illegal access of the media and video programs from networks can be prevented, based on the proposed schemes.
Joint symbol, frame, and carrier synchronization for Eureka 147 DAB system
(1997)
Sheu, CR
;
Huang, YL
;
Huang, CC
;
交大名義發表
;
電信工程研究所
We present a joint symbol, frame, and carrier synchronization method for an OFDM signal in this paper. Symbol timing is determined first by detecting an abrupt phase change in the autocorrelation of the last quarter (e.g. Eureka 147 DAB) useful symbol and its cyclic extension in the guard interval. Frequency offset of fractional carrier spacing can be estimated from the phase angle of this autocorrelation. Coarse frame synchronization or null symbol detection can also be achieved through this information. Frequency offset of integral carrier spacing and finer frame synchronizations are determined by convolution of a received phase reference symbol and several locally generated but frequency shifted phase reference symbols. Our simulation results show that this symbol timing estimation method is less sensitive to multipath fading and the frequency offset estimation is more accurate in mobile radio channels. We also show that the algorithm is robust in both AWGN and two-path fading channels for SNR down to about 8 dB.
Joint synchronization in eureka 147 DAB system based on abrupt phase change detection
(1999-10-01)
Huang, YL
;
Sheu, CR
;
Huang, CC
;
交大名義發表
;
電信工程研究所
We present a joint symbol, frame, and carrier synchronization method for the Eureka 147 DAB signal in this paper. Symbol timing is determined first by detecting an abrupt change in the phase angle of the complex product between the last quarter of a useful symbol and its cyclic extension in the guard interval. The detection of this abrupt change is based on the maximal likelihood (ML) principle. Frequency offset of fractional carrier spacing is estimated from the phase angle of the autocorrelation after symbol timing is estimated. Coarse frame synchronization and null symbol detection can also be achieved through this correlation information Frequency offset of integral carrier spacing is determined from the convolution outputs between a received phase reference symbol and several locally generated but frequency-shifted phase reference symbols. We found the length of a yard interval is the most important parameter for the synchronization algorithm to work. Simulation results show that the performance of this synchronization method approaches to the ideal synchronization case in both an additive white Gaussian noise (AWGN) channel and a two-path Rayleigh fading channel.
Network address translators: Effects on security protocols and applications in the TCP/IP stack
(2000-11-01)
Shieh, SP
;
Ho, FS
;
Huang, YL
;
Luo, JN
;
資訊工程學系
Optimal information-dispersal for fault-tolerant communication over a burst-error channel
(2003-09-01)
Shieh, SP
;
Tsai, YC
;
Huang, YL
;
資訊工程學系
;
Department of Computer Science
The (m, n) wireless information dispersal scheme (WIDS) is useful for fault-tolerant parallel wireless communications, where it can be used to tolerate up to n - m path (subchannel) failures. This paper constructs a performance model of (m, n) WIDS used in wireless communications, and proposes an algorithm to find the optimal set of (m, n) with the highest reliability. This algorithm reduces the complexity of finding the candidate set of (m, n) from O(N-2) to O(N); N is the maximum number of available sub-channels.
Practical key distribution schemes for channel protection
(2000)
Huang, YL
;
Shieh, SPW
;
Wang, JC
;
資訊工程學系
;
Department of Computer Science
This paper presents three key distribution schemes for channel protection. With the proposed schemes, encryption keys of the ordered programs can be distributed to the authorized subscribers efficiently and securely. In these schemes, for key updates, at most two messages are transmitted and simpler computation functions, including one-way hash function and XOR operation, are used to reduce the computation cost compared to existing solutions. With our key distribution schemes, only the authorized subscribers can decrypt the ordered programs. Thus, the service provider in a Pay-TV system can charge his subscribers according to their subscriptions and the intelligent property rights of TV programs can be protected by the proposed schemes.
Study of titanium tungsten nitride and tungsten nitride Schottky contacts on n-GaN
(2003-07-01)
Lee, CS
;
Chang, EY
;
Chang, L
;
Fang, CY
;
Huang, YL
The Schottky diode behaviors of the TiWNx and the WNx Schottky contacts to n-GaN were investigated at different annealing temperatures. Both TiWNx and WNx films were deposited by the reactive DC sputtering method. The WNx/n-GaN contact exhibited excellent electrical characteristics even after rapid-thermal annealing up to 850degreesC for 10s. The ideality factor and barrier height remained 1.09 and 0.8OeV, respectively, after 850degreesC annealing. However, the TiWNx/n-GaN contact was thermally stable only up to 650degreesC annealing; the values of the ideality factor and the barrier height were 1.14 and 0.76 eV, respectively, after 650degreesC annealing and started to degrade when annealed at higher temperatures. The deterioration of the TiWNx/n-GaN contact at higher temperatures was due to the inter-diffusion of the TiWN film and the GaN material.
Synchronization system of digital audio broadcasting (DAB) receiver
(1997)
Huang, YL
;
Lu, CC
;
Huang, CC
;
交大名義發表
;
電信工程研究所
We present a complete synchronization procedure for Eureka 147 DAB. Frequency offset of fractional carrier spacing is estimated first. After compensating for this frequency offset we obtain simultaneously both symbol timing and frequency offset of integral carrier spacing.