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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 22, Issue 12 - Dec 1997
Volume 22, Issue 11 - Nov 1997
Volume 22, Issue 10 - Oct 1997
Volume 22, Issue 9 - Sep 1997
Volume 22, Issue 8 - Aug 1997
Volume 22, Issue 7 - Jul 1997
Volume 22, Issue 6 - Jun 1997
Volume 22, Issue 5 - May 1997
Volume 22, Issue 4 - Apr 1997
Volume 22, Issue 3 - Mar 1997
Volume 22, Issue 2 - Feb 1997
Volume 22, Issue 1 - Jan 1997
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Performance comparison of wireless MAC protocols for wireless LANs in the radio channel with rayleigh fading, shadowing and near-far effects
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1843~1853
The channel throughput and packet delay of wireless media control (MAC) protocols with Rayleigh fading, log-normal shoadowing and near-far effects are analyzed. We consider CSMA/CA protocols as the wireless MAC protocols, since CSMA/CA protocols are based on the standard for wireless Local Area Networks (LANs) IEEE 802. 11. We have found that the performance of CSMA/CA in radion channel model is reduced above 50% than those of error free channel model in low traffic load. We also found that 4-Way Handshake CSMA/CA protocol is supterior to the other CSMA/CA protocols in high traffic load.
Test suite generation technique for protocols with nondeterminism
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1854~1866
This paper proposes a new test case generation technique for a nondeterministic finite state machine by improving the existing UIO sequence generation method. First, a new conformance relationis defined, which is one of prerequisites for automatic test case generation. Because fof the nondeterministic property of torpocols, the output of the systems under test is not known deterministically to the tester. Therefore, tree-like test case generation method is introduced for adaptive testing, in which the next input is selected after observing the previous output. Since the test cases are generated with regarding the inputs and outputs as separate events and are represented in tree notation, the test cases are easily converted into TTCN, the international standard test suite specification language.
The T-tree index recovery for distributed main-memory database systems in ATM switching systems
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1867~1879
DREAM-S is a distributed main-memory database system for the real-time processing of shared operational datra in ATM switching systems. DREAM-S has a client-server architecture in which only the server has the diskstorage, and provides the T-Tree index structure for efficient accesses to the data. We propose a recovery technique for the T-Tree index structre in DREAM-S. Although main-memory database system offer efficient access performance, the database int he main-memory may be broken when system failure such as database transaction failure or power failure occurs. Therfore, a recovery technique that recovers the database (including index structures) is essential for fault tolerant ATM switching systems. Proposed recovery technique relieves the bottleneck of the server processors disk operations by maintaining the T-Tree index structure only in the main-memory. In addition, fast recovery is guaranteed even in large number of client systems since the T-Tree index structure(s) in each system can be recovered cncurrently.
Version management of CMS-MX software
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1880~1889
CMS-MX(CDMA Mobile System-Mobile eXchange) software has a large-scale and needs frequency chanbes to adopt new functions. Therefore, an efficient version management is necessary for the software. General-purpose version management system are not suitable for the CMS-MX software, which consists of various types of files and has its own development method. In this paper, we present a version management system for the CMS-MX software. The version management system provides file registration control. version control, and information management on the basis of software configuration and soft ware developer information in accordance with CMS-MX software developement procement process. It has characteristics such as full file storing, file verification, and association with software integration process.
Performance improvement of ER switch congestion control algorithm for ABR service in ATM network
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1890~1906
A new ER feedback switch control algorithm, called EMRCA(Explicit Max-min Rate Control Algorithm), to control the ABR services traffic in the ATM networks, is proposed in this thesis. This scheme was interpreted the ACR variation residing on between a transient state and a stable state using the two thresholds that is the
in the queue to detect switch nodes congestion, and decreased the difference of minimum and maximum ACR all active connection to enhance the line bandwidth utilization. The proiposed scheme used a minimum and maximum rate of all active connections to select the connection whose the congestion rate inveoked, and uses a congestion detection mechanixm to prevent some potential cogestion by regulating selected contection.s The EMRCA scheme showed ACR variation more stable that the EPRCA scheme, also reduced buffer size of the switch, and achieved higher link utilization than the EPRCA scheme.
GDMO development environment for MIB generation
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1907~1915
The management of network in TMN defines and manages the objects which are the operating system and communication equipments in network. GDMO is used to describe thoseobjects. GDMO is not directly used for managing network, but translated into a language with object-oriented paradigm. This paper presents design and implementation of the translator which automatically translates the specification of GDMO to the object-oriented language for generating MIB(Managment Information Base). And the system includes various graphic use interface to enhance the development environment of GDMO.
An adaptive resynchronization technique for stream cipher system in HDLC protocol
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1916~1932
The synchronous stream cipher which require absoulte clock synchronization has the problem of synchronization loss by cycle slip. Synchronization loss makes the state which sender and receiver can't communicate with each other and it may break the receiving system. To lessen the risk, we usually use a continuous resynchronization method which achieve resynchronization at fixed timesteps by inserting synchronization pattern and session key. While we can get resynchronization effectively by continuous resynchroniation, there are some problems. In this paper, we proposed an adaptive resynchronization algorithm for cipher system using HDLC protocol. It is able to solve the problem of the continuous resynchronization. The proposed adaptive algorithm make resynchronization only in the case that the resynchronization is occurred by analyzing the address field of HDLC. It measures the receiving rate of theaddress field in the decision duration. Because it make resynchronization only when the receiving rate is greateer than the threshold value, it is able to solve the problems of continuous resynchronization method. When the proposed adaptive algorithm is applied to the synchronous stream cipher system in packet netork, it has addvance the result in R_e and D_e.
Development of biological signal optical transmission system
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1933~1940
The development of CMOS IC chip and external system with optical transmission sytem is proposed in this paper, which deal with 4 subject 4 channel biological signals, receive and transmit biological signals to the external system using LED and infrared light of photodiode. This system decreases the dependency of power supply voltage to the COMS IC chip. A newenforce synchronization technique using infrared bi-directional communication has ben proposed. The telemetner IC with the size of
has the followingfunctions:receiving of command signal, initialization of internal state of all functional blocks, decoding of subject selection signal, time division multiplexing of 4-channel modulated biological signals, transmission of modulated signals to external system, and auto power down control. To confirm the total telemetry system, electrocardogram is transmitted and received to the external system using optical link.
A 3.3V 30mW 200MHz CMOS upconversion mixer using replica transconductance
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1941~1948
In this paper, the power efficient linear upconversion mixer which is a functional circuit in transmit path of intermediate frequency(IF) part of Code Division Multiple (CDMA) cellular phone was explained. In generally, the low CMOS devices limits the implementation of upconversion mixer especially for lower loads. Using replica transconductor, the linear range is extended up to the limit. Thiscircuit was imprlemented using
N-well CMOS technology with 2-poly/2-metal. The active area of chip is
. The power consumption is 30mW with 3.3V suply voltage. The 1dB conpression characteristics is -27.3dB with
. load and being applied by 2-tone input signal. The mixer operates properly above 200MHz.
Designof asymmetrical coupled microstrip directional coupler on composite dielectric substrates
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1949~1956
The mode parameters of asymmetrical coupled microstrip lines on composite substrates are derived by using closed form expression. A 10 dB directional couplers, where the center frquency is 1.8 GHZ, are fabricated on a single-layer substrate and on compsite substrates respectively. It is shown that coupler on a single-layer substrate.
Blind adaptive equalizations using the multi-stage radius-directed algorithm in QAM data communications
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1957~1967
Adaptive channel equlization accomplished without resorting to a training sequence is known as blind equalization. In this paper, in order to reduce the speed of the convergence and the steady-state mean squared error simultaneously, we propose the multi-stage RD(radius-directed) algorithm derived from the combination of the constant modulus algorithm and the radius-directed algorithm. In the starting stage, multi-stage RD algorithm are identical to the constant modulus algorithm which guarantees the convergence of the equalizer. As the blind identical to the constant modulus algorithm which guarantees the convergence of the equalizer. As the blind equalizer converges, the number of the level of the quantizers is increased gradually, so that the proposed algorithm operate identical to the radius-directed algorithm which leads to the low error power after the covnergence. Therefore, the multi-stage RD algorithm obtains fast convergence rage and low steady stage mean square error.
Analysis of characteristics on symmetric/asymmetric broadside-coupled coplanar waveguide using the spectral domain approach
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1968~1974
In this paper, the spectral domain approach is employed to investigate the characteristics of symmetrical and asymmetrical broadside-coupleed coplanar waveguides(BSC-CPW). These structures have large even(c)-odd(.pi.) mode-velocity ratio, suitable for wide-band and tight-coupling microwave circuit design. Efficient design parameters can be obtained from the effective dielectric constants and characteristic impedances calculated by varying the strip widths and slot widths in the BSC-CPW structure.
An analysis of crosstalk in hihg-speed packaging interconnects using the finite difference time domain method
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1975~1984
In this paper, we analyzed the frequency characteristics and the crosstalk of the adjacent parallel lines and the crossed lines in high-speed packaging interconnections by using the three-dimensional finite difference time domain (3D FDTD) method. To analyze the actual crosstalk phenomena in the transmission of the high-speed digital sgnal, the step pulse with fast rise time was used for the source excitation signal instead of using the Gaussian pulse that is generally used in FDTD. To veify the theoretical resutls, the experimental interconnection lines that were fabricated on the Duroid substrate(
=2.33, h=0.787 [mm]) were tested by TDR(time domain reflectometry). The results show good agreement between the analyzed results and the tested outcomes.
Regularized iterative image resotoration by using method of conjugate gradient with constrain
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1985~1997
This paper proposed a regularized iterative image restoration by using method of conjugate gradient. Compared with conventional iterative methods, method of conjugate gradient has a merit to converte toward a solution as a super-linear convergence speed. But because of those properties, there are several artifacts like ringing effects and the partial magnification of the noise in the course of restoring the images that are degraded by a defocusing blur and additive noise. So, we proposed the regularized method of conjugate gradient applying constraints. By applying the projectiong constraint and regularization parameter into that method, it is possible to suppress the magnification of the additive noise. As a experimental results, we showed the superior convergence ratio of the proposed mehtod compared with conventional iterative regularized methods.
Performance evaluations of chip-spreading orthogonal code divisio moudlation system
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 1998~2004
In this paper, we have analyzed the bit error performance ofthe chip-spreading OCDM system proposed in the previous papaer and compared the results, through computer simulations, with those of conventional DS/CDMA system which employs the maximal ration combining method. WE have shown, analytically, that the BER upper bound of the OCDM system coincides with that of the conventional DS/CDMA system and the lower bound exhibits much improved results. From the simulation results, we have confirmed that the BER curves of proposed OCDM system actually lie between the two theoretical bounds and its performance is superior to that of the DS/CDMA system.
Adaptive blind equalization algorithm with dual-mode
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 2005~2013
The MCMA adaptive blind equalization algorithm has a excellent phase correction capabilities in addition to channel amplitude equalization, but has an inevitable error by mismatching between the original constellation points in arriving at the perfect equalization since unique new type constellation points are used as desired response instead of original constellation points and follows the slow convergence speed of CMA. In this paper, We propose an adaptive blind equalization algorithm with dual-mode, which has decision regions. Inside the decision regions, it operates as considering the moudlus of original data symbol point and outside the decision region, it operates as considerin gthe modulus of new constellation points. The proposed algorithm has a lower error in the steady state and rapid convergence speed toward steady state using the original data symbol points instead of new constellation points in the decision regions. From computer simulation, we confirm that the propposed algorithm has the performance superiority in residual ISI, convergence speed compared with the cnventional adaptive blind equalization algorithms, CMA, MCMA, Stop-and-Go algorithm.
Performances of wireless ATM cell transmission with partial concatenated coding
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 2014~2026
In this paper, the performances of wireless asynchronous transfer mode (ATM) cell transmission in mobile work are analyzed. We adopt 16Star QAM as amodulation technique in wireless channel and considered Reed-Solomon, convolutional, and concatenated coding to improve the error rate performances, and also proposed the Partial Concatenated Coding (PCC) technique as UEP(unequal error protection) code for efficient transmission of ATM cell in the air interface. We consider Doppler's effect, Rician fading, and diversity technique of maximal-ratio combining (MRC) for mobile channel model. For performance measure, we analyze bit error rate, ATM cell loss probability, ATM cell error probability, and network performances of ATM cell transmission delay and throughput. The numerical results show that the adoption of PCC is a prospective way for the evolution of future wireless ATM network on mobile environment.
Analysis of the congestion control scheme with the discard eligibility bit for frame relay networks
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 2027~2034
Frame relay is a fast packet switching technology that performs relaying and multiplexing frames with variable lengths over a wide area link at the T1 or E1 speed, by elminating error and flow control in the network. In frame relay networks, congestion control is typically performed through the rate enforcement with a discard eligibility (DE) bit, and the explicit negative feedback meachanisms using explicit congetion notification bits. In this paper, we consider the congestiong control scheme using the rate enforcement mechanism with DE bit for frame relay network. Assuming that each frame with exponentially distributed length arrives according to the Poission fashion, we can treat the frame relay switch as an M/M/1/K priority queueing system with pushout basis. We analyze and present the blocking probabilities and waiting time distributions of frames.
On optimal design of soft-decision multistage detectors for asynchronous DS/CDMA systems
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 2035~2042
We consider the design of soft decision functions for each stage of multistage detection for coherent demodulation in an asynchronous code-division multiple-access(CDMA) system. In particular, the sigmoid function, which is shown to be optimal under the mean square error(MSE) criterion, andmultilevel quantizers that best approximate the sigmoid function are derived. At each stage of multistage detection, the parameters of these decision functions are adjusted depending on estimated input statistics. Computer simulation results demonstrate that multistage detectors employing these soft decision functions perform considerably better than those with hard decision.
Improved changed region detection and motion estimation for object-oriented coding
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 2043~2052
The object-oriented coding technique which is one of the coding methods in very low bit rate environment is suitable for videophone image sequence. The selection of source model affect image analysis. In this paper, an image analysis method for the object-oriented coding is presented. The process is composed of changed region detection andmotion estimateion. First, we use the standard deviation of frame difference as thrreshold to extract themoving area. If thesum of gray values in mask is greater than the threshold, the center pixel of the mask is regarded as moving region. After moving is detected in changed region by edge operator, observation point is determined from moving region. The motion is estimated by 6-parameter mapping method with determined observation point. The experimantal resutls show that the proposed method can significantly improve the image quality.
Modified three step search using adjacent block's motion vectors
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 2053~2061
The motion comensated video coding technology is very improtant to compress video signal since it reduces the temporal redundancies in successive frames. But the computational complexity of the motion estimation(ME) is too enormous to use in the area of real-time and/or resolution video processing applications. To reduce the complexity of ME, fast search algoritjms and hardware design methods are developed. Especially, the three step search(TSS) is well known method which shows stable performance in various video sequences. And other variations of TSS are developed to get better performance andto reduce the complexity. In this paepr, we present the modified TSS using neighboring block's motion vectors to determine first step motion vector in TSS. The presented method uses the correlation of the adjacent blocks with same motion field. The simualtion resutls show that it has a good MAE performance and low complexity comparing with original TSS.
A study on the analysis of the characteristics of synchronization clock in the SDH based linear network
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 2062~2073
The important articles we must consider in SDH network and system design are the number of maximum nodes and clock characteristics of each node. In order to get these, the study of characteristics about some clock states, such as normal state and phase transient state, on the standard specifications is required. In this paper, we presented MTIE and TDEV characteristics with ITU-T & ANSI standard specifications in some clock states of the SDH linear networks, and proposed the number of maximum nodes satisfying above two standards. Also our resulsts are compared with AT&T's.
(0, k) Run-Length Limited(RLL) Data Compression Codes for Digital Storage Systems
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 2074~2079
Much recent work has been done in the two related areas of source coding for data compression, and channel coding for data storage, respectively. We propose two (0, k) run-lengh limited(RLL) data compression codes for the storage that combine source and channel coding. It was shown that the propsoed codes approach the maximum code rate of (0, k) code as k increase. Thus, the overall code rate of storage system can be increased by using the combined source/channel coding as compared to the conventional 8/9 code which is popular in hard drive systems Functhermore, one can also reduce the complexity of modulation coding procedure by using already RLL constrained data.
An efficient storing method of multiple streams based on fixed blocks in disk parititions
The Journal of Korean Institute of Communications and Information Sciences, volume 22, issue 9, 1997, Pages 2080~2089
Recent evolution in compute technology makesthe multimedia processing widely availiable. Conventional storage systems do not meet the requirements of multimedia data. Several approaches were suggested to improve disk storing methods for them. Bocheck proposed a disk partitioning technique for multiple steams assuming that all steams have same retrieval intervals with the same amount data for each access. While Bocheck's one provides a good method for same period, it does not consider the case of different periods of continous media streams. This paper proposes a new partitioning technique in which a fixed number of blocks are assigned for stresms with different retrieval periodicity. The analysis shows this problem is the same as the one scheduling the steams into a given sequence. The simulation was done to compare the proposed m-sequence merge method with the conventional Scan-EDF and Partitioning methods.