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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Korean Institute of Communications and Information Sciences
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The Korean Institute of Communications and Information Sciences
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Volume & Issues
Volume 32, Issue 12C - Dec 2007
Volume 32, Issue 12B - Dec 2007
Volume 32, Issue 12A - Dec 2007
Volume 32, Issue 11C - Nov 2007
Volume 32, Issue 11B - Nov 2007
Volume 32, Issue 11A - Nov 2007
Volume 32, Issue 10C - Oct 2007
Volume 32, Issue 10B - Oct 2007
Volume 32, Issue 10A - Oct 2007
Volume 32, Issue 9C - Sep 2007
Volume 32, Issue 9B - Sep 2007
Volume 32, Issue 9A - Sep 2007
Volume 32, Issue 8C - Aug 2007
Volume 32, Issue 8B - Aug 2007
Volume 32, Issue 8A - Aug 2007
Volume 32, Issue 7C - Jul 2007
Volume 32, Issue 7B - Jul 2007
Volume 32, Issue 7A - Jul 2007
Volume 32, Issue 6C - Jun 2007
Volume 32, Issue 6B - Jun 2007
Volume 32, Issue 6A - Jun 2007
Volume 32, Issue 5C - May 2007
Volume 32, Issue 5B - May 2007
Volume 32, Issue 5A - May 2007
Volume 32, Issue 4C - Apr 2007
Volume 32, Issue 4B - Apr 2007
Volume 32, Issue 4A - Apr 2007
Volume 32, Issue 3C - Mar 2007
Volume 32, Issue 3B - Mar 2007
Volume 32, Issue 3A - Mar 2007
Volume 32, Issue 2C - Feb 2007
Volume 32, Issue 2B - Feb 2007
Volume 32, Issue 2A - Feb 2007
Volume 32, Issue 1C - Jan 2007
Volume 32, Issue 1B - Jan 2007
Volume 32, Issue 1A - Jan 2007
Selecting the target year
A New Hop-Timing Estimator with a Normalized Envelop Detector and an Early-Late Filter
Lee, Ju-Hyung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 355~361
In this paper, the hop-timing estimator, which NED and ELF are adopted to, has been proposed. The estimation performance of the proposed scheme and the conventional scheme is compared through computer simulations. The simulation results show that the new system has less hop-timing error than the conventional system in partial band noise jamming channel. The lover Eb/Nj and ratio of jamming bandwidth(rho) we, the bigger performance enhancement of the proposed system is.
Performance and Operating Characteristics Analysis of the 16-APSK Modulation over Nonlinear Channels
Kang, Seok-Heon ; Kim, Sang-Tae ; Sung, Won-Jin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 362~369
APSK (Amplitude Phase Shift Keying) digital modulation is characterized by the circular positioning of the transmission symbols in the constellation diagram. Due to such structural characteristics, the peak-to-average power ratio of the APSK modulation is lower than that of the QAM (Quadrature Amplitude Modulation), and the amount of performance degradation over nonlinear channels can be mitigated. The APSK modulation scheme has recently been adopted as satellite communication system standards including the DVB-S2 (Digital Video Broadcasting - Satellite, Version 2). In this paper, a BER (Bit Error Rate) upper bound approximation formula is derived using the channel model with the output power saturation characteristics, and its accuracy is demonstrated. Using the derived formula, the input power level that minimizes the BER is determined. The optimized performance based on the radii ratio of the 16APSK constellation and the channel saturation level is also presented.
Low Density Parity Check Codes for Hybrid ARQ System
Kim, Woo-Tae ; Kim, Jeong-Goo ; Joo, Eon-Kyeong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 370~378
The most appropriate low density parity check (LDPC) code for hybrid automatic repeat request (HARQ) system suitable for future multimedia communication systems is presented in this paper. HARQ system with punctured LDPC code is investigated at first. And two transmission schemes with parallel concatenated LDPC code are also presented and their performances are analyzed according to the various values of mean column weight (MCW). As a result, the parallel concatenated LDPC code with the diversity effect of information bit is considered to be more appropriate for HARQ system considering the throughput as well as error performance.
An FPGA Implementation of High-Speed Adaptive Turbo Decoder
Kim, Min-Huyk ; Jung, Ji-Won ; Bae, Jong-Tae ; Choi, Seok-Soon ; Lee, In-Ki ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 379~388
In this paper, we propose an adaptive turbo decoding algorithm for high order modulation scheme combined with originally design for a standard rate-1/2 turbo decoder for B/QPSK modulation. A transformation applied to the incoming I-channel and Q-channel symbols allows the use of an off-the-shelf B/QPSK turbo decoder without any modifications. Adaptive turbo decoder process the received symbols recursively to improve the performance. As the number of iterations increase, the execution time and power consumption also increase as well. The source of the latency and power consumption reduction is from the combination of the radix-4, dual-path processing, parallel decoding, and early-stop algorithms. We implemented the proposed scheme on a field-programmable gate array (FPGA) and compared its decoding speed with that of a conventional decoder. From the result of implementation, we confirm that the decoding speed of proposed adaptive decoding is faster than conventional scheme by 6.4 times.
An Effective Medical Image System using TFT-DXD Method's Digital X-ray Detector
Hwang, Jae-Suk ; Lee, Jae-Kyun ; Lee, Chae-Wook ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 389~395
The Film X-ray and the CCD method of current medical image system have the disadvantages such as required large place and diagnosis time. In this paper, we implement an effective medical image system using TXT-DXD method's digital X-ray detector(DR1000C). The implemented medical image system has advantages of placing efficiency and short diagnosis time. In order to make the image out of the system more effective, we develop an LCD(Liquid Crystal Display) control driver, having the resolution of 1900*1200. And we propose an enhancement unsharp masking method to update image enhancement of DR1000C medical image system, and compare it with the current methods.
Fast PDE Algorithm Using Block Matching Error Prediction
Sin, Se-Ill ; Oh, Jeong-Su ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 396~400
This paper proposes the fast partial difference elimination (PDE) algorithm. When the conventional PDE cannot skip the rest of matching procedure in a candidate block using a partial matching error, the proposed algorithm estimates to skip it again using the block matching error predicted from the computed partial matching error. The proposed algorithm can eliminate impossible candidate blocks earlier than the conventional PDE since the predicted block matching error is always bigger than the partial matching error. The simulation results show that the proposed algorithm can significantly reduce the computations while keeping image quality as good as the conventional PDE.
Real-time Water Quality Monitoring System Using Vision Camera and Multiple Objects Tracking Method
Yang, Won-Keun ; Lee, Jung-Ho ; Cho, Ik-Hwan ; Jin, Ju-Kyong ; Jeong, Dong-Seok ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 401~410
In this paper, we propose water quality monitoring system using vision camera and multiple objects tracking method. The proposed system analyzes object individually using vision camera unlike monitoring system using sensor method. The system using vision camera consists of individual object segmentation part and objects tracking part based on interrelation between successive frames. For real-time processing, we make background image using non-parametric estimation and extract objects using background image. If we use non-parametric estimation, objects extraction method can reduce large amount of computation complexity, as well as extract objects more effectively. Multiple objects tracking method predicts next motion using moving direction, velocity and acceleration of individual object then carries out tracking based on the predicted motion. And we apply exception handling algorithms to improve tracking performance. From experiment results under various conditions, it shows that the proposed system can be available for real-time water quality monitoring system since it has very short processing time and correct multiple objects tracking.
Adaptive Model-Based Quantization Parameter Decision for Video Rate Control
Kim, Seon-Ki ; Ho, Yo-Sung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 411~417
The rate control is an essential component in video coding to provide better quality under given coding constraints, such as channel capacity, frame rates, etc. In general, source data cannot be described as a single distribution in a video coding, hence it can cause an exhaustive approximation problem. It drops a coding efficiency under weak channel environments, such as mobile communications. In this paper, we design a new quantization parameter decision model that is based on a rate-distortion function of generalized Gaussian distribution. In order to adaptively express various source data distribution, we decide a shape parameter by observing a ratio of samples, which have a small value. For experiment, the proposed algorithm is implemented into H.264/AVC video codec, and its performance is compared with that of MPEG-2 TM5, H.263 TMN8 rate control algorithm. As shown in simulation results, the proposed algorithm provides an improved quality rather than previous algorithms and generates the number of bits closed to the target bits.
A Simplified Time Domain Channel Tracking Scheme in OFDM Systems with Null Sub-Carriers
Jeon, Hyoung-Goo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 418~424
This paper proposes a scheme to track channel response in OFDM systems with null sub-carriers. The proposed channel tracking scheme estimates the channel response first in the frequency domain by using the decision directed data. The time domain channel estimation is then performed to remove additive white Gaussian noise (AWGN) components further. Due to the channel estimation in the frequency domain, no inverse matrix calculation is required in the time domain channel estimation. Computational reduction in the proposed method is about 93%, compared with the conventional time domain channel estimation method. Mean square error (MSE) and bit error rate (BER) performances are evaluated by using computer simulation. The proposed method shows the same performance as that of the conventional time domain channel estimation even though the significant computational reduction.
Fast Modulation Classifier for Software Radio
Park, Cheol-Sun ; Jang, Won ; Kim, Dae-Young ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 425~432
In this paper, we deals with automatic modulation classification capable of classifying incident signals without a priori information. The 7 key features which have good properties of sensitive with modulation types and insensitive with SNR variation are selected. The numerical simulations for classifying 9 modulation types using the these features are performed. The numerical simulations of the 4 types of modulation classifiers are performed the investigation of classification accuracy and execution time to implement the fast modulation classifier in software radio. The simulation result indicated that the execution time of DTC was best and SVC and MDC showed good classification performance. The prototype was implemented with DTC type. With the result of field trials, we confirmed the performance in the prototype was agreed with the numerical simulation result of DTC.
Approximation of the Performance Loss of an Adaptive Array due to a Neighboring Interferer
Hong, Young-Jin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 433~439
This paper derives an approximate expression for the output SINR(Signal to Interference plus Noise Ratio) of Applebaum type adaptive array under the scenario of the interferer's proximity to the desired signal. The approximation is made in terms of array geometry, the arrival direction of desired signal and that of an interfering signal. An interferer in the close proximity of target signal is shown to drastically impair the away performance. An approximate expression for interferer arrival direction which results in a predetermined performance loss is also obtained in terms of array configurations. Proposed approximation agrees with the computer calculated performance impairment when the two signals are apart by less than eight degrees. The allowable proximity of the interfering signal increases with the number of array elements.
A New Sparse Matrix Analysis of DFT Similar to Element Inverse Jacket Transform
Lee, Kwang-Jae ; Park, Dae-Chul ; Lee, Moon-Ho ; Choi, Seung-Je ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 440~446
This paper addresses a new representation of DFT matrix via the Jacket transform based on the element inverse processing. We simply represent the inverse of the DFT matrix following on the factorization way of the Jacket transform, and the results show that the inverse of DFT matrix is only simply related to its sparse matrix and the permutations. The decomposed DFT matrix via Jacket matrix has a strong geometric structure that exhibits a block modulating property. This means that the DFT matrix decomposed via the Jacket matrix can be interpreted as a block modulating process.
Analysis of Performance for SC-FDE Systems Using Proportional Adaptive Equalizer in
Frequency Radio Channel Models
Yang, Yong-Seok ; Lee, Kyu-Tae ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 447~453
In the multipath fading channel, OFDM(Orthogonal Frequency Division Multiplexing)system possess the characteristics of ISI/ICIwith prefix, but a weak point of circuit complexity and PAPR problem. SC-FDE(Single Carrier with Frequency Domain Equalization) performance is similar to OFDM system, but equalizer is complex in frequency domain. In this paper, simple proportional equalizer offer for SC-FDE system, it useful method in the
channel model such as indoor, outdoor, SUI. It prove using MATLAB simulation, speed faster then OFDM system, reduce terminal complexity in same test condition.
Design and Implementation of the Security Components in Ultra-Lightweight Mobile Computing Environment
Park, Rae-Young ; You, Yong-Duck ; Lee, Young-Seok ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 454~461
The next-generation computer is the ultra-lightweight mobile computer that communicates with peripheral handhold devices and provides dynamically the services appropriate to user. To provide the dynamic services on the ultra-lightweight mobile computer, security problem for user or computer system information should be solved and security mechanism is necessary for the ultra-lightweight mobile computing environment that has battery limit and low performance. In this paper, the security mechanism on the component based middleware for the ultra-lightweight mobile computer was implemented using RC-5 cipher algorithm and SHA-1 authentication algorithm. The security components are dynamically loaded and executed into the component based middleware on the ultra-lightweight mobile computer.
Low Complexity MIMO System Using Minimum Distance Searching Algorithm (MDSA) with Linear Receiver
Kwon, Oh-Ju ;
The Journal of Korean Institute of Communications and Information Sciences, volume 32, issue 4C, 2007, Pages 462~467
This paper proposes Minimum Distance Searching Algorithm (MDSA) which reduces the computational complexity (CC) of the ML, the kind of Spatial Multiplexing (SM) MIMO system. The MDSA searchs candidate symbols with a starting symbol, which is called reference bits. We used the linear receiver of MIMO techniques to find a starting symbol. The MDSA searchs the shortest path to a transmitted symbol using reference bits and Minimum Distance(MD) concept. The CC of MDSA is reduced to the 0.21% to the ML as the transmit antennas is 4 in 16QAM. The simulation result shows the BER of MDSA is nearly same to the BER of ML as the transmit antennas is 2 and the receive antennas is 3 in 16QAM and slightly degraded to the BER of ML as the transmit antennas is 4 and the receive antennas is 6 in QPSK.