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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Electronics and Telecommunications Research Institute
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Volume & Issues
Volume 28, Issue 6 - Dec 2006
Volume 28, Issue 5 - Oct 2006
Volume 28, Issue 4 - Aug 2006
Volume 28, Issue 3 - Jun 2006
Volume 28, Issue 2 - Apr 2006
Volume 28, Issue 1 - Feb 2006
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An All-Optical Gain-Controlled Amplifier for Bidirectional Transmission
Choi, Bo-Hun ; Hong, Kyung-Jin ; Kim, Chang-Bong ; Won, Yong-Hyub ;
ETRI Journal, volume 28, issue 1, 2006, Pages 1~8
A novel all-optical gain-controlled (AOGC) bidirectional amplifier is proposed and demonstrated in a compact structure. The AOGC function using fiber Bragg grating (FBG) pairs controls both directional signals independently, and combinations of optical interleavers and isolators suppress Rayleigh backscattering (RB) noise. The amplifier achieves high and constant gain with a wide dynamic input signal range and low noise figure. The performance does not depend on the input signal conditions, whether static-state or transient signals, or whether there is symmetric or asymmetric data traffic on bidirectional transmission. Transmission comparison experiments between invariable symmetrical and random variable asymmetric bidirectional data traffic verify that the all-optical gain control and bidirectional amplification functions are successfully combined into this proposed amplifier.
A Low-Crosstalk Design of 1.25 Gbps Optical Triplexer Module for FTTH Systems
Kim, Sung-Il ; Park, Sun-Tak ; Moon, Jong-Tae ; Lee, Hai-Young ;
ETRI Journal, volume 28, issue 1, 2006, Pages 9~16
In this paper, we analyzed and measured the electrical crosstalk characteristics of a 1.25 Gbps triplexer module for Ethernet passive optical networks to realize fiber-tothe-home services. Electrical crosstalk characteristic of the 1.25 Gbps optical triplexer module on a resistive silicon substrate should be more serious than on a dielectric substrate. Consequently, using the finite element method, we analyze the electrical crosstalk phenomena and propose a silicon substrate structure with a dummy ground line that is the simplest low-crosstalk layout configuration in the 1.25 Gbps optical triplexer module. The triplexer module consists of a laser diode as a transmitter, a digital photodetector as a digital data receiver, and an analog photodetector as a cable television signal receiver. According to IEEE 802.3ah and ITU-T G.983.3, the digital receiver and analog receiver sensitivities have to meet -24 dBm at
and -7.7 dBm at 44 dB SNR. The electrical crosstalk levels have to maintain less than -86 dB from DC to 3 GHz. From analysis and measurement results, the proposed silicon substrate structure that contains the dummy line with
space from the signal lines and 4 mm separations among the devices satisfies the electrical crosstalk level compared to a simple structure. This proposed structure can be easily implemented with design convenience and greatly reduce the silicon substrate size by about 50 %.
BER Performance of Cooperative Transmission for the Uplink of TDD-CDMA Systems
Van, Khuong Ho ; Kong, Hyung-Yun ;
ETRI Journal, volume 28, issue 1, 2006, Pages 17~30
In time division duplex (TDD) code division multiple access (CDMA) systems, chip-synchronous transmission in the uplink is obtainable, thus leading to free multiple access interference in flat Rayleigh fading channels plus additive white Gaussian noise. This motivates us to develop a novel cooperative transmission strategy that allows single-antenna devices to benefit from spatial diversity using orthogonal signature sequences. The proposed cooperation is applicable to many digital modulation methods and achieves the fullest diversity level, low implementation complexity, and a full data rate. Closed-form bit-error-rate expressions were also derived and compared to simulation results in order to evaluate its validity. A variety of numerical results demonstrated the cooperation's superiority over single transmission under the same transmit power constraint.
Analysis of Distributed DDQ for QoS Router
Kim, Ki-Cheon ;
ETRI Journal, volume 28, issue 1, 2006, Pages 31~44
In a packet switching network, congestion is unavoidable and affects the quality of real-time traffic with such problems as delay and packet loss. Packet fair queuing (PFQ) algorithms are well-known solutions for quality-of-service (QoS) guarantee by packet scheduling. Our approach is different from previous algorithms in that it uses hardware time achieved by sampling a counter triggered by a periodic clock signal. This clock signal can be provided to all the modules of a routing system to get synchronization. In this architecture, a variant of the PFQ algorithm, called digitized delay queuing (DDQ), can be distributed on many line interface modules. We derive the delay bounds in a single processor system and in a distributed architecture. The definition of traffic contribution improves the simplicity of the mathematical models. The effect of different time between modules in a distributed architecture is the key idea for understanding the delay behavior of a routing system. The number of bins required for the DDQ algorithm is also derived to make the system configuration clear. The analytical models developed in this paper form the basis of improvement and application to a combined input and output queuing (CIOQ) router architecture for a higher speed QoS network.
Stability of an Amorphous Silicon Oscillator
Bae, Byung-Seong ; Choi, Jae-Won ; Kim, Se-Hwan ; Oh, Jae-Hwan ; Jang, Jin ;
ETRI Journal, volume 28, issue 1, 2006, Pages 45~50
An RC oscillator using amorphous silicon thin film transistors was developed. The oscillation frequency and its dependence on resistance and bias voltage were studied. The frequency was controlled by adjusting the feedback resistance of the oscillator. The highest measured frequency of the oscillator was around 140 kHz, which is acceptable for low-end radio frequency identification (RFID). Since a low-end RFID circuit needs low cost and a simple process, an amorphous silicon oscillator is suitable.
Image Restoration by Lifting-Based Wavelet Domain E-Median Filter
Koc, Sema ; Ercelebi, Ergun ;
ETRI Journal, volume 28, issue 1, 2006, Pages 51~58
In this paper, we propose a method of applying a lifting-based wavelet domain e-median filter (LBWDEMF) for image restoration. LBWDEMF helps in reducing the number of computations. An e-median filter is a type of modified median filter that processes each pixel of the output of a standard median filter in a binary manner, keeping the output of the median filter unchanged or replacing it with the original pixel value. Binary decision-making is controlled by comparing the absolute difference of the median filter output and the original image to a preset threshold. In addition, the advantage of LBWDEMF is that probabilities of encountering root images are spread over sub-band images, and therefore the e-median filter is unlikely to encounter root images at an early stage of iterations and generates a better result as iteration increases. The proposed method transforms an image into the wavelet domain using lifting-based wavelet filters, then applies an e-median filter in the wavelet domain, transforms the result into the spatial domain, and finally goes through one spatial domain e-median filter to produce the final restored image. Moreover, in order to validate the effectiveness of the proposed method we compare the result obtained using the proposed method to those using a spatial domain median filter (SDMF), spatial domain e-median filter (SDEMF), and wavelet thresholding method. Experimental results show that the proposed method is superior to SDMF, SDEMF, and wavelet thresholding in terms of image restoration.
Learning Behaviors of Stochastic Gradient Radial Basis Function Network Algorithms for Odor Sensing Systems
Kim, Nam-Yong ; Byun, Hyung-Gi ; Kwon, Ki-Hyeon ;
ETRI Journal, volume 28, issue 1, 2006, Pages 59~66
Learning behaviors of a radial basis function network (RBFN) using a singular value decomposition (SVD) and stochastic gradient (SG) algorithm, together named RBF-SVD-SG, for odor sensing systems are analyzed, and a fast training method is proposed. RBF input data is from a conducting polymer sensor array. It is revealed in this paper that the SG algorithm for the fine-tuning of centers and widths still shows ill-behaving learning results when a sufficiently small convergence coefficient is not used. Since the tuning of centers in RBFN plays a dominant role in the performance of RBFN odor sensing systems, our analysis is focused on the center-gradient variance of the RBFN-SVD-SG algorithm. We found analytically that the steadystate weight fluctuation and large values of a convergence coefficient can lead to an increase in variance of the center-gradient estimate. Based on this analysis, we propose to use the least mean square algorithm instead of SVD in adjusting the weight for stable steady-state weight behavior. Experimental results of the proposed algorithm have shown faster learning speed and better classification performance.
Characteristics of Individuals Influencing Adoption Intentions for Portable Internet Service
Kim, Moon-Koo ; Jee, Kyoung-Yong ;
ETRI Journal, volume 28, issue 1, 2006, Pages 67~76
This study aims to identify the factors that influence adoption intentions towards portable Internet service, based on the individual characteristics that assist in creating markets and developing strategies. Two types of factors are defined: individual characteristics including demographics, existing services usages, prior knowledge, adoption attitudes, and service evaluations; and adoption intentions including the willingness to subscribe, subscription term, willingness to pay, usage type, and preferred terminal. The results indicate that the importance of demographic variables depends on adoption intentions, and that users of mobile Internet service and wireless LAN are probably targets for portable Internet service. Furthermore, the results demonstrate the need for an enhanced perception of the usefulness and ease of use of service, as well as an intensive marketing activity for potential users and a bearable innovation to stimulate the market for portable Internet service.
A QoS-Guaranteed Cell Selection Strategy for Heterogeneous Cellular Systems
Guo, Qiang ; Xu, Xianghua ; Zhu, Jie ; Zhang, Haibin ;
ETRI Journal, volume 28, issue 1, 2006, Pages 77~83
In order to improve the accuracy of cell selection in heterogeneous cellular systems, this paper proposes a fuzzy multiple-objective decision-based cell selection (FMDCS) strategy. Since heterogeneous cellular systems have different access technologies and multiple traffic classes, the strategy adopts cell type, data rate, coverage, transmission delay, and call arrival rate as evaluation indices, and uses different weight vectors according to the traffic classes of the mobile host. Then, a fuzzy multiple-objective decision algorithm is applied to select the optimal cell from all candidates. This paper also gives an instance analysis and simulation. The instance analysis shows FMDCS makes different selections for different traffic classes. Simulation results of the after-handoff quality-of-service (QoS) show the selected cell can provide MH optimal service.
Small-Sized High-Power PIN Diode Switch with Defected Ground Structure for Wireless Broadband Internet
Kim, Dong-Wook ;
ETRI Journal, volume 28, issue 1, 2006, Pages 84~86
This letter presents a small-sized, high-power single-pole double-throw (SPDT) switch with defected ground structure (DGS) for wireless broadband Internet application. To reduce the circuit size by using a slow-wave characteristic, the DGS is used for the quarter-wave (
/4) transmission line of the switch. To secure a high degree of isolation, the switch with DGS is composed of shunt-connected PIN diodes. It shows an insertion loss of 0.8 dB, an isolation of 50 dB or more, and power capability of at least 50 W at 2.3 GHz. The switch shows very similar performance to the conventional shunt-type switch, but the circuit size is reduced by about 50% simply with the use of DGS patterns.
A Full Rate Quasi-orthogonal STF-OFDM with DAC-ZF Decoder over Wireless Fading Channels
Jin, Ji-Yu ; Ryu, Kwan-Woong ; Park, Yong-Wan ;
ETRI Journal, volume 28, issue 1, 2006, Pages 87~90
In this letter, we propose a quasi-orthogonal space-time-frequency (QOSTF) block coded orthogonal frequency division multiplexing (OFDM) that can achieve full symbol rate with four transmit antennas. Since the proposed QOSTF-OFDM cannot achieve full diversity, we use a diversity advantage collection with zero forcing (DAC-ZF) decoder to compensate the diversity loss at the receiving side. Due to modulation advantage and collected diversity advantage, the proposed scheme exhibits a better bit-error rate performance than other orthogonal schemes.
Coexistence of OSCR-Based IR-UWB System with IEEE 802.11a WLAN
Wu, Weiwei ; Huang, Han ; Yin, Huarin ; Wang, Weidong ; Wang, Dong-Jin ;
ETRI Journal, volume 28, issue 1, 2006, Pages 91~94
Impulse radio (IR) is a competitive candidate for ultra-wideband (UWB) systems. In this letter, we evaluated the coexistence of an IR-UWB system based on an orthogonal sinusoidal correlation receiver (OSCR) with an IEEE 802.11a WLAN through a detailed simulation. The coexistence performance of the two systems is characterized in terms of the receiver's bit-error rates. Then, some approaches to interference mitigation are discussed.
A Novel M-ary Code-Selected Direct Sequence BPAM UWB Communication System
Bai, Zhiquan ; Kwak, Kyung-Sup ;
ETRI Journal, volume 28, issue 1, 2006, Pages 95~98
In this letter, a novel M-ary code-selected direct sequence (DS) ultra-wideband (UWB) communication system is presented. Our purpose is to achieve a high data rate by an M-ary code-selected direct sequence bipolar pulse amplitude modulation (MCSDS-BPAM) scheme. In this system, a particular DS code sequence is selected by the
/2 bits from the DS gold code set. This scheme can accomplish both a high data rate without increasing the system bandwidth or changing the pulse shape and improve the BER with an increase of modulation level M even at a lower signal-to-noise ratio (SNR). The receiver signal processing algorithm is given for an MCSDS-BPAM UWB system over an ideal AWGN channel and correlation receivers.
Enhanced Dynamic Segment Protection in WDM Optical Networks under Reliability Constraints
Guo, Lei ; Cao, Jin ; Yu, Hongfang ; Li, Lemin ;
ETRI Journal, volume 28, issue 1, 2006, Pages 99~102
In this letter, we study the protection problem in wavelength division multiplexing (WDM) optical networks, and propose a novel dynamic heuristic algorithm called differentiated reliable segment protection (DRSP). Differing from previous work, DRSP can effectively avoid the trap problem and is able to find a feasible solution for each connection request. Therefore, DRSP outperforms the previous work. Simulation results have shown to be promising.
A PLC-Based Optical Sub-assembly of Triplexer Using TFF-Attached WDM and PD Carriers
Han, Young-Tak ; Park, Yoon-Jung ; Park, Sang-Ho ; Shin, Jang-Uk ; Kim, Duk-Jun ; Park, Chul-Hee ; Park, Sung-Woong ; Kwon, Yoon-Koo ; Lee, Deug-Ju ; Hwang, Wol-Yon ; Sung, Hee-Kyung ;
ETRI Journal, volume 28, issue 1, 2006, Pages 103~106
We have fabricated a planar lightwave circuit (PLC) hybrid-integrated optical sub-assembly of a triplexer using a thin film filter (TFF)-attached wavelength division multiplexer (WDM) and photodiode (PD) carriers. Two types of TFFs were attached to a diced side of a silica-terraced PLC platform, and the PD carriers with a
mirror on which pin-PDs were bonded were assembled with the platform. A clear transmitter eye-pattern and minimum receiver sensitivity of -24.5 dBm were obtained under 1.25 Gb/s operation for digital applications, and a second-order inter-modulation distortion (IMD2) of -70 dBc was achieved for an analog receiver.
Development of Korean Male Body Model for Computational Dosimetry
Lee, Ae-Kyoung ; Choi, Woo-Young ; Chung, Min-Suk ; Choi, Hyung-Do ; Choi, Jae-Ick ;
ETRI Journal, volume 28, issue 1, 2006, Pages 107~110
The dimensions of the human body vary by age, sex, and race. The internal structure and outer dimensions of a body exposed to an electromagnetic field is important for accurate dosimetry. The average physical size of Korean adult males between the ages 18 to 24 was investigated, and a male volunteer was selected whose physical condition is within the physical standards,
. Magnetic resonance images and partially computerized tomography images of the volunteer were acquired. The intervals between the transverse images were 1 mm for the head and 3 mm for the rest of the body. About 30 different tissues were manually classified by an anatomist on the raw images, and the segmented images were implemented in the form of a text file appropriate for numerical formulation.
A Biosignal-Based Human Interface Controlling a Power-Wheelchair for People with Motor Disabilities
Kim, Ki-Hong ; Kim, Hong-Kee ; Kim, Jong-Sung ; Son, Wook-Ho ; Lee, Soo-Young ;
ETRI Journal, volume 28, issue 1, 2006, Pages 111~114
An alternative human interface enabling people with severe motor disabilities to control an assistive system is presented. Since this interface relies on the biosignals originating from the contraction of muscles on the face during particular movements, even individuals with a paralyzed limb can use it with ease. For real-world application, a dedicated hardware module employing a general-purpose digital signal processor was implemented and its validity tested on an electrically powered wheelchair. Furthermore, an additional attempt to reduce error rates to a minimum for stable operation was also made based on the entropy information inherent in the signals during the classification phase. In the experiments, most of the five participating subjects could control the target system at their own will, and thus it is found that the proposed interface can be considered a potential alternative for the interaction of the severely disabled with electronic systems.
A Simple Model Parameter Extraction Methodology for an On-Chip Spiral Inductor
Oh, Nam-Jin ; Lee, Sang-Gug ;
ETRI Journal, volume 28, issue 1, 2006, Pages 115~118
In this letter, a simple model parameter extraction methodology for an on-chip spiral inductor is proposed based on a wide-band inductor model that incorporates parallel inductance and resistance to model skin and proximity effects, and capacitance to model the decrease in series resistance above the frequency near the peak quality factor. The wide-band inductor model does not require any frequency dependent elements, and model parameters can be extracted directly from the measured data with some curve fitting. The validity of the proposed model and parameter extraction methodology are verified with various size inductors fabricated using
Multi-granularity Switching Structure Based on Lambda-Group Model
Wang, Yiyun ; Zeng, Qingji ; Jiang, Chun ; Xiao, Shilin ; Lu, Lihua ;
ETRI Journal, volume 28, issue 1, 2006, Pages 119~122
We present an intelligent optical switching structure based on our lambda-group model along with a working scheme that can provide a distinctive approach for dividing complicated traffic into specific tunnels for better optical performance and grooming efficiency. Both the results and figures from our experiments show that the particular channel partition not only helps in reducing ports significantly, but also improves the average signal-to-noise ratio of the wavelength channel and the blocking performance for dynamic connection requests.