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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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Volume & Issues
Volume 24, Issue 12B - Dec 1999
Volume 24, Issue 12A - Dec 1999
Volume 24, Issue 11A - Nov 1999
Volume 24, Issue 10B - Oct 1999
Volume 24, Issue 10A - Oct 1999
Volume 24, Issue 9B - Sep 1999
Volume 24, Issue 9A - Sep 1999
Volume 24, Issue 8B - Aug 1999
Volume 24, Issue 8A - Aug 1999
Volume 24, Issue 7B - Jul 1999
Volume 24, Issue 7A - Jul 1999
Volume 24, Issue 6B - Jun 1999
Volume 24, Issue 6A - Jun 1999
Volume 24, Issue 5B - 00 1999
Volume 24, Issue 5A - 00 1999
Volume 24, Issue 4B - 00 1999
Volume 24, Issue 4A - 00 1999
Volume 24, Issue 3B - 00 1999
Volume 24, Issue 3A - 00 1999
Volume 24, Issue 2B - 00 1999
Volume 24, Issue 2A - 00 1999
Volume 24, Issue 1B - 00 1999
Volume 24, Issue 1A - 00 1999
Volume 24, Issue 12 - 00 1999
Volume 24, Issue 11B - 00 1999
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A design of the minimum bandwidth binary line MB34d for optical transmission
Lee, Dong Il ; Kim, Dae Yeong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 155~155
Frequency offset estimation of an OFDM system using window function and correlator in the multipath fading channel
Jo, Dong Gyun ; Kim, Nam Su ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 162~162
in this paper, we propose an estimation technique for a frequency offset that this is the major disadvantage of OFDM method in the frequency selective slow fading chanenel and drive error variance for its perpormance analysis in the limited range. We use the estimation technique having the correlation relationship between two continuous sample signals with window function and compose the expanded DFTAFC loop in order to track frequency offset. From the analysis results, it is represented that the proposed algorithm is better than the established method in -term of tracking range, interference suppression and error perpormance as the frequency offset or transmission power and founded that the estimation value of approximately driven error variance in the limited range is well corresponding the really computed value.
Design of an Efficient TDL Filter for Wireless Communications and its Performance Evaluation
Seo, Seung Wan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 173~173
Since the direct-form filter sums several bits at on cycle, it should operate at low speed when the number of taps is increased. To increase the operating grequency, the transpose-form filter using a pipeline scheme has been proposed. However, the transpose-form filter requires a large number of gates. this paper proposes a tapped delay line (TDL) filter considering time delay and and hardware size and evoluates performance. Although the proposed filter using efficient pipeline schemes requires larger number of gates compared with the direct-form filter, it increase the clock speed compared with direct-form filter and requires less number of gate compared with transpose-form filter. Appying the proposed TDL filter of 128 taps for the CDMA standard, IS-95, can reduce the gate count by the more then 30% compared with the transpose-form filter without sacrificing the clock speed. In the addition, although the proposed TDL filter increases the gate count about direct-form filter, that can increase the clock speed about 200% compared with the direct-form filter
Improved Fast Cell Search Algorithm for DS-CDMA Mobile Radio System employing Asynchronous Inter-cell
Park, Yong Seo ; Song, Mun Gyu ; Jeong, Yeong Ji ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 179~179
In the DS-CDMA based cellular radio system, asynchronous inter-cell operation which assigns the unique code to each cell can be realized cells. But generally it takes much more time for cell search than syncnronous inter-cell option. In this paper the improved fast cell search algorithm to be able to succeed search cell faster than conventional one was proposed and simulated by computer. The pipeline principle was applied to the proposed algorithm through cell search process. In the case of failure of cell search, the cell search processes restart instead of returning to the first step of cell search processes by updating the signals for cell seaech at the point of its failure. Simulation results show that the proposed algorithm could apparently reduce the cell search time.
Adaptive synchronization method for frequency hopping communication system
Han, Seong U ; Jeon, Yong Eok ; Jeon, Byeong Min ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 187~187
The frequency hopping(FH) communication system could transmit the information through the air under the heavy jamming or monitoring conditions. In this paper, we designed the FH communication system, and proposed the adaptive initial synchronization algorithm on the FH communication system, which can avoid the jamming monitoring for the transmitting information under the lowest communication condition. this algorithm, different from conventional methods, can change the sending duration and number of the frequency for initial synchronization according to the communication conditions. Therefore, we could reduce the duration of synchronization and get the high synchronization probability and the low detection possibility of the information Consequntly we could minimize the delay time on the initial synchronization. Through the simulation, this adaptive synchronization algorithm has proved that get the FH synchronization and doesn't have the false alarm under the heavy jamming condition.
Performance of the Symbol Timing Recovery for 16QAM System in Frequency Nonselective Channel
Mun, Jae Gyeong ; O, Gil Nam ; Park, Jae Hong ; Ha, Yeong Ho ; Kim, Su Jung ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 196~196
In this paper, we analyzed performance of the symbol timing recovery scheme for 16QAM Ratio system. As a symbol timing recovery scheme, both maximum amplitude method(MAM) and wave difference method (WDM) are analyzed employing a pulse shaping filter, such as raised cosine filter(RCF) and nonlinear filter(NLF). Simulation result shows that the jitter performance of MAM or WDM using NLF is better than that using square root RCF. In order to estimate and compensate for the Rayleigh fading PSAM(Pilot symbol assisted Modulation) and apace diversity are also employed. Consequently, BRP performance 10-⁴is obtained for Eъ/Nо=20dB
Performance Analysis of the Packetized Voice Traffic in the Mobil trunking systems with ALL type 2 protocol
Jeon, Hae Won ; Lee, Yeong Gyo ; Park, Gi Sik ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 204~204
In this paper, we introduced the current trend of standardization for AAL 2 which provides for the bandwidth-efficient transmission for low-rate such as compressed voice, short and variable length packets in delay sensitive application. And we set up model to which we apply between BSC and MSC in the celluar mobil telecommunication system. Also, we performed analysis of trunk capacity, delay, and transmission efficiency used in packetized voice traffic. According to the simulation results, overlapping scheme is better efficient than non-overlapping scheme. Also, we knew that optimum transmission buffer size is 4 ATM cells. Finally, we expect that the proposed method of the performance analysis and the results may be used to the basic reference for the constructing IMT-2000 telecommunication networks
Performance Anaysis of Demmapper using Channel State Information in DVB-T System
Lee, Won Cheol ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 211~211
This paper is the concerning about the performance analysis of demapper which use the scattered pilot signals inserted in transmission part in COFDM(Coded Orthogonal Frequency Division Multiplexing) system that is the standard transmission system of digital terrestrial broadcasting. The digital data to be transmitted are mapped according to the mapping method which is depend on the constellation in transmission part and are demapped according to the distance difference between transmitted point in constellation diagram. In receiver part, at first, the scattered pilots are extracted in pilot extractor block and extracted scattered pilots are interpolated in time direction and in frequency direction respectively. By the interpolation the scattered pilot signals channel state information(csi) is deriver and this information is used in demapper block. This paper was simulated above method in Rayleigh and Ricean fading 20 multi-path channel that is the defined in ETS 300 744. From the simulation results, we obtained the 2.5~3dB better performance in Rayleigh fading and 0.5dB in Ricean fading without the changing of the Viterbi decoder structure in comparison with the conventional soft decision demapping method so concluded that this papers method is very efficient and be used in OFDM IC.
Design and Implementation of CC-OQPSK Modulator for IMT-2000
Cheon, Ho Cheol ; Baek, Ju Gi ; Bang, Seong Il ; Jin, Yeon Gang ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 219~219
In this paper, the CC-OQPSK modulator for IMT-2000 is designed and implemeneted. The CC-OQPSK system is realized by using FPGA circuit which is easy to be implemented as the ASIC. this modulation method has better spectral and power efficiency than conventional QPSK system because it has constant envelope characteristics.
Algorithm for VP Based Resourse Management in Interworking betweem Public B-ISDN and ATM LAN
Jeong, Il Yeol ; Lee, Sang Mok ; Lee, Sang Hong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 227~227
The most important issue in internetworking between public B-ISDN and ATM network may be how to support incoming traffic from private ATM networks at a public B-ISDN. This paper proposes a new algorithm to computer VP bandwidth based on VP resource management dynamically. The algorithm computer required VP bandwidth for homogeneous traffic sources with minimal computation cost, and for further application of heterogeneous traffic sources DVA(dynamic VP bandwidth Allocation) algorithm is proposed to computer virtual VP bandwidth for each homogeneous traffic sources. The algorithm proposed will minimize the uncertainty of incoming traffic from private ATM networks to a public B-ISDN, and the efficient VP based resource management scheme of the algorithm will be useful for guaranteed QoS of network service in the interworking between public B-ISDN and private ATM network.
A Synchronization Algorithm for Distributed Multimedia Services in ATM Network
Lee, Dong Eun ; No, Seon Sik ; Lee, Bong Ju ; Kim, Yeong Seon ; Kim, Yeong Cheon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 237~237
In this paper, we propose a synchronization algorithm based on the estimation scheme and QOS characteristics of media in order to provide efficient synchronization by considering delay and QOS characteristics of distributed multimedia services in ATM networks. The proposed algorithm computers end-to-end control time of the network by using the delay characteristics and QOS characteristics such as packet loss rate of each virtual channel in the distributed environment that utilize different clock between various media sever located in the distributed network and receiver sites. Also we propose resynchronization algorithm that adapt to new network environment by transmitting the new end-to-end control time to sender sites are asynchronization situation arise from network.
A Study on the Improvement og Cell Discarding and Average Delay in proportion to Cell Transmission rate in ATM
Lee, Sang Tae ; Kim, Nam Hui ; No, Gi Yong ; Jeon, Byeong Sil ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 248~248
In this paper, we propose a new priority control mechanism which is to balance the cell loss rate by measuring, in real time, the number of discarded cells in the queuing system with a different loss priority for each class of service such that each class of service meets its cell loss rate requirement. And, to reduce the delay rate we modified existing cell scheduling scheme. The proposed cell scheduling scheme is operated based on the delay factors(cell delay time, cell numbers in the buffer, and delay priority number). To determine the cell to be sent in output buffer, a controller for each address buffer adds up the delay factors. The cell which has the largest value is served. And, throughout the computer simulation, the existing methods and scheme is compare with respect to cell loss rate and average delay time. In the result of simulation, the proposed scheme have more improved performance than the other schemes with respect to cell loss rate and average delay time.
Performance Analysis of A Wavelength Division Multiple Access Protocol using A Equilibrium Point Method
Jo, Won Hong ; O, Yeong Yeol ; Heo, Nam Jo ; Lee, Jae Yong ; Lee, Sang Bae ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 257~257
A protocol for high speed optical fiber LAN using a wavelength division multiple access (WDMA) passive star topology is proposed. The protocol is analyzed using a equilibrium point analysis(EPA) method on the system with finite users. The wavelength division multiple access on multi-channels is basically accomplished by the slotted Aloha protocol as used in many previous works. While many works have used the S-G(throughput-load)method for the infinite used, the derived Markov chain is soled by the EPA for a protocol analysis with finite users, which can present the performance and the instability problem in the slotted Aloha system with a finite population. In addition to this mathematical analysis, we showed the relation between the analyzed infinite population system and the analyzed finite population system and proved the correctness of its analysis.
Study on the Date Exploration with Modified Self-organizing maps
Jin, Yeong Geun ; Kim, Tae Gyun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 266~266
Date exploration is new field which explores unknown hugh data set and find data structures or characteristics hidden on the data and make it possible to estimate data behavior. In this paper we suggest on-line data exploration method based on modified Kohoren Self-Organizing Map. Som which uses unsupervised learning shows good characteristic in data clustring. We modified SOM to apply to on-line data clustering keeping its good characteristic. Simulation result showed the effectiveness of suggested methods compare with on-line K-means methods.
An optical ladder filter Ⅱ using optical fiber and directional coupler
Lee, Chae Uk ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 274~274
The digital ladder filter has different cintinued fractional expansions due to the types of ladder filter and it can or can not be realized by given transfer function. In this paper, considering the Ⅱ typa of ladder digital filter, we design formulae and cindition of realibility for optical fibers and directional couplers.
Nonlinear Response Effect of Noise in A bistable Stochastic Neural System
Han, Sang Baek ; Jeong, Dong Gyu ; Kim, Su Yong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 283~283
It is well known that the of addition of noise to a weak signal in some nonlinear dynamic systems can increase the performance of the signal, phenomenon belonging to a class of noise-induced cooperative behavior known as stochastic resonance(SR). In this paper we investigate the nonlinear-response effect of the noise added to external input on action potential in the continuous model of Hopfield neural system, which shows the stochastic resonance. For the analysis we propose a method to measure the nonlinear system performance. The proposed method is to use the Shannon’s mutual information between input and output. Here the external input and action potential can be treated respectively as input and output in mutual information. The mutual information needs the probability density functions (PDFs) of the input and output as well as their joint PDF. To derive the PDF of the action potential as the output, we introduce Fokker-Planck equation. The simulation results show the mutual information versus the noise intensity of the external input, which, with existence of noise, shows the exhibit extrema of mutual information for certain value of the noise intensity.
An efficient FDTD analysis of the microwave circuits using the network parameter conversion
Park, Myeon Ju ; Kim, Byeong Seong ; Nam, Sang Uk ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 290~290
This paper proposed a simple and efficient method for the accurate calculation of the scattering parameters of various microwave circuits using the FDTD method. In the proposed method, a circuit parameter which concerns the net current/voltages of each ports is first calculated, and is converted into S parameter using the network theory, which is different from the conventional method in which the S parameter of the circuit is directly calculated from the incident and reflected waves obtained through two independent FDTD simulations. The proposed method can eliminate the error in the calculated circuit parameters due to the imperfect absorbing boundary condition of the FDTD in an effective way. Furthermore, there is no need for an extra FDTD simulation to get the incident wave if the characteristic impedance of the transmission line is known (e.g in the waveguide problems) the method of this paper can be applied to wide areas including waveguide and various planar transmission line circuits and can improve the accuracy and of the FDTD analysis in a very simple way.
Motion Compensation by Affine Transform using Edge Infomation of Image
Park, Hyo Chan ; Hwang, Chan Sik ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 297~297
A BMA(Block Matching Algorithm) causes block artifacts in very low bit rate video coding, accordingly, a motion compensation method using an transform has been proposed as a solution to this problem. When image are divided using an affine transform, there is an increase in the prediction errors of the compensated image and distortion will occur as image object do not necessarily conform to triangular patterns. In this paper, we propose a method that first divides an image into triangular patches according to its edge information and than divides the image into more detailed triangular patches where a higher standard deviation of difference image occurs. The experimental results indicate that the proposed scheme improve both the objective and the subjective quality of an image when compared with H.263
Subband Coding of Video with Adaptive Vector Quantization Using Motion Infomation
Lee, Beop Gi ; Choe, Jeong Hyeon ; Kim, Deok Gyu ; Jeong, Won Sik ; Lee, Geon Il ; Lee, Gyeong Hwan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 306~306
In this paper, we propose a subband coding of video with adaptive vector quantization using motion information. In video coding, the overall coding efficiency depends on the combined performance of the interframe predictor and the intraframe encoder. Therefore, to improve the coding efficiency, we should use motion information when we encode the motion compensated difference image (MCDI). The characteristics of subband images of MCDI show that the energy of subband images increase as the magnitude of motion vectors increase. In proposed method, we classify the subband images according to their motion vectors and adaptively vector quantize the subband images using the codebook designed for each class. By doing so, we can minimize the side information required to transmit the class index and we can get the reconstructed image with good image quality.
Image Segmentation using Histogram Clustering and Nonuniform Quantization technique
Choe, Yun Seok ; Lee, Gyeong Hun ; Go, Seong Je ;
The Journal of Korean Institute of Communications and Information Sciences, volume 24, issue 2B, 1999, Pages 313~313
In this paper, we propose an image segmentation algorithm based on histogram clustering and nonuniform quantization, which is applicable to images with very complicated histograms. Conventional histogram-based image segmentation techniques are commonly used for segmenting simple images with the bi-modal histogram into segmentation techniquies are commonly used for segmenting simple images with the bi-modal histogram into distinguishable objects and background. However, it is difficult to apply those techniques to images with complicated multi-modal histogram. Accordingly, in this paper, we propose an image segmentation algorithm based on histogram clustering and nonuniform quantization. In the proposed algorithm, an input image is simplified using morphological filters, and the histogram is generated form flat regions in the simplified image.The segmented image is obtained by quantizing the simplified image with nonuniform quantization step which are determined by clustering the multi-modal histograms. Finally, region merging is carried out to eliminate tiny segmented regions from segmented image. Experimental results show that the proposed histogram based segmentation algorithm can be an alternative to the conventional segmentation algorithm.