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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 23, Issue 9A - Sep 1998
Volume 23, Issue 8 - Aug 1998
Volume 23, Issue 7 - Jul 1998
Volume 23, Issue 6 - Jun 1998
Volume 23, Issue 5 - May 1998
Volume 23, Issue 4 - Apr 1998
Volume 23, Issue 9 - 00 1998
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A Design of Routing Path and Wavelength Assignment with Minimum Number of Wavelengths in WDM Optical Transport Network
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1883~1892
This paper considers the efficient design of routing path and wavelength assignment asignment in the sigle-hop WDM optical transport networks. The connecton demands between node-pairs are given and a connection must be made by only one lightpath. It is assumed that no wavelength conversion is allowed and the physical topology of the network is given. This paper proposes a method to find the routes of lightpaths and assign wavelengths to the routes, which minimizes the number of total wavelength to satisfy all connection demands. We establish a new optimization model that finds the minimum number of wavelengths. A heuristic algorithm with polynomial iterations is developed for the problem. The algorithm is implemented and applied to the netowrks with real problem size. The results of the application are compared with the commericial optimization solver, GAMS/OSL and Wauters & Demeester .
10 Gbps transmission performance for self-phase modulation and chirping
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1893~1898
We have redefined the
-parameter of the extended transmitters in the presence of self-phase modulation (SPM) induced chirp. The
-parameter is effectively lowered to about 1, when the SPM effect with the launching power of 12.5dBm (maximum launching power to avoid stimulated Brillouin scattering(SBS)) is included, compared to the
-parameter of the transmitter algone. The lowered
-parameter has improved the transmission performance significantly regardless the transmitter is operated with positive or negative chirp. The SPM-induced effective
-parameter can be used as a design parameter for the high speed (10 Gbps) transmission systems.
Bandwidth allocation on VBR source traffic in high capacity ATM link
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1899~1906
In ATM switching system link bandwidth is one of the improtant resources. Thus ATM switching system must allocate the bandwidth to the users efficiently and guarantee the QoS. Especially to guarantee the QoS of the VBR traffic source such as video, users must declare the traffic characteristics and QoS expectations using UPC parameters. The CAC can use two multiplexig models in variation to link capacity and connection number. One is loseless multiplexing model; the second is a statistical multiplexing model. The loseless multiplexing model performs best when the number of mutiplexed sources is small, but as the number of multiplexed sources is increase the CAC must use the statistical multiplexing model. In this paper, the statistical multiplexing models are studied, which are suitable for high capacity ATM link on VBR traffic sources. The satistical multiplexing model and the loseless multiplexing model are combined. In statistical model we map the UPC parameters provided by new VBR connection to appropriate source traffic model. In the high capacity ATM link, as the connection number increases, the statical multiplexing gain increases.
An Adaptive Connection Admission Control Method Based on the Measurement in ATM Networks
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1907~1914
This paper proposes the adaptive connection admission cotrol using the variale MRR(measurement reflection ratio) and the distribution of the number of cells arriving during the fixed interval. This distribution is estimated from the measured number of cells arriving at the output buffer during the fixed interval and traffic parameters specified by user. MRR is varied by the difference of estimated distribution and measurement distribution. As MRR is adaptively varied by estimated distribution error of accepted connections, it quickly reduces estimation error. Also, the scheduling scheme is proposed for multiplexed traffic with various traffic characteristics. For each traffic class, this scheme estimates adaptively equivalent bandwidth and schedules according to equivalent bandwidth ratio of each traffic class, so it improves cell loss rate and link utilization.
A study on hypothetical switching software through of the analysis of failure data
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1915~1925
The switching system software is large scale, real-time multi-task system which requires high reliability. The reliability assessment of large-scale software is very important for the success of software development project. For this raeson, the software quality measurement is much more important. In this paper, we have learned about the software reliability, metho of the analysis of failure data and estimation of software quality. To estimate the software reliability, using the failure data found during of the system test. We apply the two software reliability growth models, named Goel-Okumoto(G-O) and S-shaped model, to estimate the software reliability. Also, we compared with the results and we reviewed fully not only development cycle but validation and verification of the test data, for each software versions. This paper presents a software reliability model that suitale the software development project and the activeity of quality control for the switching system.
Performance evaluation of fully-interconnected ATM switch (part II: for bursty traffic andnonuniform distribution)
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1926~1940
This paper is the part II of research results on the performance evaluation of fully interconnected ATM switch, and includes the performance evaluation results for bursty traffic and nonuniform distribution. The switch model is a fyully interconnected switch type proposed by ETRI and is the proper architecutre for a small-sized switch element. The proposed switch consists of two steps of buffering scheme in the switch fabric in order to effectively absorb the effect of bursty nature of ATM traffic. The switch uses bit addressing method for addressing shcmeme and thus it is easy to implement multicasting function without adding additional functional block. In order to incorporate the bursty nature of traffic in ATM networks, we use IBP(Interrupted Bernoulli Process) model as an input traffic model as well as random traffic model which has been used as a traditional traffic model. In order to design the various scenarios for simulation, we considered both uniform and nonuniform output distribution, and also implemented multicast function. In this paper, we presented the simulation results in diverse environments and evaluated the performance of the switch.
Circuit Design of Frquency Hopping Wireless LAN PLCP Sublayer
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1941~1951
In this paper, hardware circuit that performs functions of IEEE 802.11 wireless LAN frequency hopping PLCP protocol is designed using 0.8 um CMOS cmn8a technology of the COMPASS. Transmission rate of the designed hardware is 1Mbps. The designed circuit have about 6300 gates and
area. In order to verify the circuit, two PLCP circuits are interconnected and frames are transmitted from one PLCP circuit to the other PLCP circuit. As a results of the simulation, we conclude that the designed PLCP circuit works well as the IEEE 802.11 standard specification.
An Analysis of Radio Interference in 800MHz-Band between Korea and Japan
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1952~1962
Radio interference ahs been occurred in TRS service on the south seashore in Korea from 1994. After monitoring the radio signal interference, it is found that the main reasons of radio interference are due to the source stations located at Fukuoka and Yamaguchi in Japan. However, Japan didn't agree about this fact, based on the their technique evaluationof the radio signal; since the distance (about 240-300km) of the radio station between Fukuoka and Pusan is enough to separate from the interference, the radio signal from Digital Mobile Phone is Japan cannot be reached to Pusan area in Korea. In this paper, we verified that the main sources of radio interference are a ducting propagation generated from Japan area by using the computer simulation technique and the measuring data.
A study of a planar active phased array antenna using two-dimensionally coupled slot-lines
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1963~1970
In this paper, a two-dimensional slotline coupling structure is proposed for the planar active phased array antenna system with scanning the beam by coupled oscillators without phase shifters. The operating characteristics are analyzed and experimentally demonstrated. The proposed two-dimensional slotline coupling structure consists of
-type slotline in the ground plane for the coupling of E-plane and H-plane. From the simulation results of coupling strength with the variation of width, length and the number of slotlines, the optimal coupling structure is proposed and applied to
elements of planear phased array antenna. The experimental results show that the beamwidth of E-plane and H-pland are
, respectivly, and the scanning range is from
from the broadside. Therefore, it is shown the two-dimensional slotline coupling structure for oscillator-type active phased array antenna can be applied to the planar phased array antenna system.
A study on the fromat converter of GA-HDTV
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1971~1976
This paper is a study on the improved version of the conventional format converter. This paper paper descries three interface systems used to record and play back the compressed digital data from the Grand Alliance(GA) HDTV system. The first interface is for recording the compressed data from the GA-HDTV to the HDVCR system, the second is for the GA-HDTV to the D3 VTR and the third is for the HDVCR to D3 VTR. This interface is also designed to accept both 8 VSB and 16 VSB modes. It is expected that this paper to be valuable in bringing the compressed HDTV recoding technology into television studios, cable head ends and consumer homes.
Algorithm-based fault tolerant vector convolution on array processor
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1977~1983
An algorithm-based fault tolerant scheme for the vector convolution is proposed employing the positive and negative checksum vectors that are defined in this paper based on the encoder vector. The proposed scheme is implemented on the aray processor, and then the amount of redundancy is examined thrugh the complexity analysis.
Performance of the adaptive LMAT algorithm for various noise densities in a system identification mode
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1984~1989
Convergence properties of the stochastic gradient adaptive algorithm based on the least mean absolute third (LMAT) error criterion is presented.In particular, the performnce of the algorithmis examined and compared with least mena square (LMS) algorithm for several different probability densities of the measurement noisein a system identification mode. It is observedthat the LMAT algorithm outperforms the LMS algorithm for most of the noise probability densities, except for the case of the exponentially distributed noise.
A study on the performance analysis of a weather radar using an adaptive array antenna
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1990~1997
It is very essential to remove a strong ground clutter and moving clutter for an extraction of accurate information from a Doppler weather radar. Therefore, this paper proposed the use of an adaptive array antenna to overcome the shortages of a conventional weather radar. In the first, a simulation method was suggested for the generation of clutter and weather signals. Using these data, the performance of a weather radar was analyzed under various conditions. It is shown that the quality of pulse-pair estimates was greatly improved from the simulation results.
Moving object segmentation and tracking using feature based motion flow
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 1998~2009
An effective algorithm for tracking rigid or non-rigid moving object(s) which segments local moving parts from image sequence in the presence of backgraound motion by camera movenment, predicts the direction of it, and tracks the object is proposed. It requires no camera calibration and no knowledge of the installed position of camera. In order to segment the moving object, feature points configuring the shape of moving object are firstly selected, feature flow field composed of motion vectors of the feature points is computed, and moving object(s) is (are) segmented by clustering the feature flow field in the multi-dimensional feature space. Also, we propose IRMAS, an efficient algorithm that finds the convex hull in order to cinstruct the shape of moving object(s) from clustered feature points. And, for the purpose of robjst tracking the objects whose movement characteristics bring about the abrupt change of moving trajectory, an improved order adaptive lattice structured linear predictor is used.
Forward rate control of MPEG-2 video based on distortion-rate estimation
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2010~2024
In video coding, it is important to improve the average picture quality as well as to maintain cosistent picture quality between consecutive pictures. In this paper, we propose a distortion-rate estimation method for MPEG-2 video and a forward rate control method, using the proposed estimation result, to be able to obtain the improved and consistent picture quality of CBR (Constant Bit Rate) encoded MPEG-2 video. The proposed distortion-rate estimation enable us to predict the distortion and the bits generated from an encoded picture at a given quantization step size and vice versa. The most attactive features of proposed distortion-rate estimation are its accuracy and low computational complexity enough to be applied to the practical video coding. In addition, the proposed rate control first determined a quantization parameter per frame by following procedure: distortion-rate estimation, target bit allocation, distortion constraint and VBV(Video Buffer Verification) constraint. And then this quantization parameter is applied to the encoding so that improved and consisten picture quality can be obtained. Furthermore the proposed rate control method can solve the error propagation problem caused by scene change or anchor picture degradation by using the B-picture skipping and the guarantee of the minimum bit allocation for the anchor picture. Experimental results, comparing the proposed forward rate control method with TM5 method, show that the proposed method makes more improed and consistent picture quality than TM5.
A bit-rate control of MPEG-2 video coding using quantization ratio coefficient and the mean MQUANT
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2025~2031
In moving picture coding standard MPEG2, a bit rate control system plays a key role for the compressing ratio and picture quality. We proposed a bit rate control scheme which assigns more bits to I, P frames and uses the average MQUANT of previous mackoblocks. The proposed scheme showed about 0.9dB improvement of image quality when compared to bit rate control method of MPEG2 Test-Model5.
A Novel Bit Allocation Method Using Two-phase Optimization Technique
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2032~2041
In this work, we propose a novel bit allocation method that is to minimize overall distortions subject ot the bit rate constraint. We partition the original bitallocation problem into 'macroblock level bit allocation' problems that can be solved by conventional Lagrangian mutiplier methods and a 'frame level bit allocation' problem. To tackle the frame level problem, 'two-phase optimization' algorithm is used with iter-frame dependency model. While the existing approaches are almost impossible to find the macroblock-unit result for the moving picture coding system due to high computational complexity, the proposed algorithm can drastically reduce the computational loads by the problem partitioning and can obtain the result close to the optimal solution. Because the optimally allocated results can be used as a benchmark for bit allocation methods, the upper performance limit, or a basis for approximation method development, we expect that the proposed algorithm can be very useful for the bit allocation related works.
Aggregated Bandwidth Smoothing Method of Multiple-stored Videos for VoD Services over a Shared-medium Channel
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2042~2051
VBR compressed, pre-recorded video is known to exhibit significant, multiple time-scale bit rate variability. To reduce the variability and burstiness of the aggregated transmission rate as low as possible, in this paper, we present an adaptive bandwidth smoothing algorithm, that can be effectively applicalble for VoD services over a shared-medium channel. For these environments where many clients are connected to a single server, by introducing the conventional MVBA(minimum variability bandwidth allocation) algorithm and controlling adaptively the conventional MVBA(minimum variability bandwidth asllocation) algorithm and controlling adaptively the aggregated transmission rate whenever a new clients request is arrived at the server side, the proposed algorithm effectively reduces the burstiness and variability of the aggregated transmission rate. Through computer experiments, it is shown that the proposed method perporms better than the convertional non-aggregated bandwidth smoothing schemes in terms of the peak rate, standard deviation, number of rate changes for the aggregated traffic.
Radio location algorithm in microcellular wide-band CDMA environment
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2052~2063
Various full-scale radio location systems have been developed since ground-based radio navigation systems appeared during World War II, and more recently global positioning systems (GPS) have been widely used as a representative location system. In addition, radio location systems based on cellular systems are intensively being studied as cellular services become more and more popular. However, these studies have been focused mainly on macrocellular systems of which based stations are mutually synchronized. There has been no study about systems of which based stations are asynchronous. In this paper, we proposed two radio location algorithms in microcellular CDMA systems of which base stations are asychronous. The one is to estimate the position of a personal station at the center of rectangular shaped area which approximates the realistic common area. The other, as a method based on road map, is to first find candidate positions, the centers of roads pseudo-range-distant from the base station which the personal station belongs to and then is to estimate the position by monitoring the pilot signal strengths of neighboring base stations. We compare these two algorithms with three wide-spread algorithms through computer simulations and investigate interference effect on measuring pseudo ranges. The proposed algorithms require no recursive calculations and yield smaller position error than the existing algorithms because of less affection of non-line-of-signt propagation in microcellular environments.
Design of digital clock level translator with 50% duty ratio from small sinusoidal input
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2064~2071
A new digital clock level translator has been designed in order to produce a clock source of the internal logic circuits. The translator output has 50% duty ratio from small sinusoidal input such as TCXO which oscillates itself in poratable components. The circuit consists of positive and negative comparators, RS latch, charge pump, and reference vol- tage generator. It detects pulse width of the output waveform and feedbacks the control signal to the input com-parator. It detects pulse width of the output waveform and feedbacks the control signal to the input com-parator reference, producing output waveform with valid 50% duty ratio of the digital signal level. The designed level translator can be used as a sampling clock source of ADC, PLL and the colck source of the clock synthesizer. The circuit wasdesigned in a 0.8.mu.m analog CMOS technology with double metal, double poly, and BSIM3 circuit simulation model. From our experimental results, a stable operating characteristics of 50 +3% duty ratio was obtained from the sinusoidal input wave of 370 mV.
Pseudo-inverse-filtering type decorrelating detector for asynchronous CDMA channels
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2072~2079
In this paper, we propose a new decorrelating detector called pseudo-inverse-filtering type decorrelating detector for asynchronous CDMA channels. We first show that the matched filtering and decorrelating operations of the existing decorrelating detectors can be replaced with the pseudo-inverse filtering operations in synchronous channels, and using this fact we show that the decorrelating detector has the largest SNR among the linear detectors that can eliminate MAI. Then we introduce asynchronous pseudo-inverse filtering type decorrelating detector by extending this result for asynchronous channels, and discuss implementation methods of the proposed decorrelating detectors. Since the proposed scheme employs a decentralized structure for updating coefficients, it has the flexibility to add/remove users. Finally we analyze the performance of the proposed decorrelating detector in terms of the bit error rate, and examine its performance improvements over the conventional detectors through computer simulations.
Mobile Location Estimation for PCS
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2080~2089
The microcellular architectures based on the smaller size increase the possibilities of frequent handover, thereby necessitating additional control procedures for providing communication services. This paper proposes a technique for estimating the mobile location in the microcellular architecutre. It can be utilized for many purposes such as increasing the effectiveness of channel allocation strategies. Simulations are performed to analyze the estimation accuracy of the proposed technique.
Analysis of the Percentage Articulation and Voice Packet Loss over the Internet
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2090~2095
In this paper, we measured voice packet loss over the Korean Internet and analyzed percentage articulation by variation of the packet loss. To do this, we reviewed real-time transmission service based on RTP/UDP/IP and test method of the transmission quality. and implemented the real-time speech transmission system using GSM and UDP/IP. Monosyllable list has been chosen for the percentage articulation test, each voice packet has been coded and compressed by GSM and it has sequence number to measured packet loss and to recover out-of-order packets. In transmission results using seven router over the Korean Internet, we have show that loss rates reached 1.6% (unload), 22.5%(load) and loss rates after packet recovery by resequencing and FEC are from 9% to 35%. Finally, we have shown that percentage articulations by variation of the network traffic are Table 4.
CPN Management Model and Network Access Flow/Congestion Control in ATM Network
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2096~2105
As there can be coincident bursts which may result in congetsion in a node of ATM network, reactive flow control schemes are required to guarantee user's Quality of Service. But, the high speed characteristics of ATM networks make it difficult to control source transmission rate in reacting to congestions in intermediate nodes. Therefore, flow control in Customer Premise Network may be more efficient than end-to-end flow control. In this paper, we propose a management model for flow ontrol in CPN and new Network Access Flow/Congestsion control scheme to utilize efficiently Virtual Path Connection.
A Study on Sharing of Transmission Antenna for AMPS/CDMA Systems
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2106~2112
In this paper, we propose an antenna sharing scheme between 800 MHz AMPS and CDMA systems using CDMA transmission antenna. We restructured the path of signals such that signals from two systems use AMPS amplifier or CDMA amplifier. The performance of proposed scheme is compared with currently operating system's performance in terms of call connection rate, call completion rate and dropped-call rate after implementing proposed method to the AMPS/CDMA basestation. The results show that the voice quality and call connection of the proposed system is comparable to that of the commercial systems. The number of antenna at the base station can be reduced without performance degradation if the proposed transmission antenna sharing scheme and previously reported receiving antenna sharing technique are used together.
Search space pruning technique for optimization of decision diagrams
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2113~2119
The optimization problem of BDDs plays an improtant role in the area of logic synthesis and formal verification. Since the variable ordering has great impacts on the size and form of BDD, finding a good variable order is very important problem. In this paper, a new variable ordering scheme called incremental optimization algorithm is presented. The proposed algorithm reduces search space more than a half of that of the conventional sifting algorithm, and computing time has been greatly reduced withoug depreciating the performance. Moreover, the incremental optimization algorithm is very simple than other variable reordering algorithms including the sifting algorithm. The proposed algorithm has been implemented and the efficiency has been show using may benchmark circuits.
Design of Core of MPEG Decoder for Object-Oriented Video on Network
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 8, 1998, Pages 2120~2130
This paper concerns a design of programmable MPEG decoder for video processing by object unit on network. The decoder can process video data effectively by a embedded controller with stack buffers for supporting OOP (Object-Oriented Programming). The controller offers extended instructions that process several data types including 32bit integer type. In addition to that, we have a vector processor, in this decoder that can execute advanced compensation and prediction by half pixel and SA(Shape Adaptive)-IDCT of MPEG-4. Absolutors and halfers in the vector processor make this architecture extensive to a encoder. We verified the decoder with
5-Volt CMOS COMPASS library.