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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 27, Issue 12C - Dec 2002
Volume 27, Issue 11C - Nov 2002
Volume 27, Issue 10C - Oct 2002
Volume 27, Issue 10A - Oct 2002
Volume 27, Issue 9C - Sep 2002
Volume 27, Issue 8C - Aug 2002
Volume 27, Issue 8B - Aug 2002
Volume 27, Issue 8A - Aug 2002
Volume 27, Issue 7C - Jul 2002
Volume 27, Issue 7B - Jul 2002
Volume 27, Issue 7A - Jul 2002
Volume 27, Issue 6C - Jun 2002
Volume 27, Issue 6B - Jun 2002
Volume 27, Issue 6A - Jun 2002
Volume 27, Issue 5C - May 2002
Volume 27, Issue 4C - Apr 2002
Volume 27, Issue 4B - Apr 2002
Volume 27, Issue 4A - Apr 2002
Volume 27, Issue 3C - Mar 2002
Volume 27, Issue 3B - Mar 2002
Volume 27, Issue 3A - Mar 2002
Volume 27, Issue 2B - Feb 2002
Volume 27, Issue 2A - Feb 2002
Volume 27, Issue 2C - Jan 2002
Volume 27, Issue 1C - Jan 2002
Volume 27, Issue 1B - Jan 2002
Volume 27, Issue 1A - Jan 2002
Volume 27, Issue 9 - 00 2002
Volume 27, Issue 8 - 00 2002
Volume 27, Issue 3 - 00 2002
Volume 27, Issue 12 - 00 2002
Volume 27, Issue 11 - 00 2002
Volume 27, Issue 10 - 00 2002
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A Study on the Outage Probability of Mobile Communication System using HAPS
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 275~280
Wireless communications have been developed time and time to satisfy more demands of users for internet service, mobile communication service and so on. One of infrastructures leading the next generation wireless communication is HAPS(High Altitude Platform Station). This paper analyzed outage probability when a mobile communication system was constructed by using HAPS. First, an approach to evaluate the carrier to interference power ratio' was introduced and results from the analysis were calculated and simulated. from the results, carrier to interference power ratio (C/I) and fading depth (K) had an effect on outage probability; outage probability decreases when K increases far constant C/I or C/l increases for constant K. In addition, when outage probability for a platform with elevation 30 degrees is expanded into it for 24-platforms, outage probability(C/I=9.8dB) was worse because of many interferers relatively.
An Efficient Packet Forwarding Method for Internet an IP-based Wireless Access Network
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 281~290
In this paper, we propose an efficient packet forwarding method for an IP-based wireless Internet access network. Packets are forwarded along with a flow, that is a kind of connection-oriented connection and established before delivering packets. For this purpose, we also propose a flow resolution method and a modified IPv6 header for delivering packet in the wireless Internet access network. In addition, the method to support the mobility of mobile stations is explained, and the implementation issues are discussed. In order to estimate the performance of the proposed method, we analyzed the delay time to deliver packets in the wireless Internet access network. The numerical results show that the proposed method is very efficient, in the view point of delay.
Performance Analysis of MC/DS-CDMA System with Smart Antenna
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 291~297
Due to the increasing demand for high data multimedia service, there has been progressing study of adaptive smart antenna to increase both the performance and capacity using limited wireless resource. IS-95 scheme in the origin of cdma2000 of IMT-2000 standard uses signals of spreading and Walsh-Orthogonal Modulation in reverse link. But, in the case of reverse lint there exists difficulty in synchronous of signals transmitted from users. Therefore, orthogonality between users is not satisfied. So, asynchronous MC-CDMA scheme may yield low performance. In this paper, MC/DS-CDMA scheme to reverse link transmission in adaptive array antenna environment is proposed for spreading the S/P-converted data streams using a given spreading code. Due to frequency diversity effect, simulation results show that the proposed system provides improved BER performance and narrow band interference supple psi on.
A Constrained Adaptive Space-Time Interference Canceller for Multiuser WCDMA Systems
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 298~307
This paper concentrates on developing and analyzing an advanced space-time multiuser receiver for WCDMA forward link. Through exploring the interference caused by co-channel users and delayed multipaths in CDMA, a constrained linear adaptive filter is adopted to cancel the interference. Furthermore, by utilizing the space-time diversity, an optimum diversity receiver, called a constrained adaptive space-time interference canceller (C-ASTIC), is proposed. For comparison, the statistical analysis of multiuser performance for WCDMA system with space-time diversity is described. The result of the simulation showed that C-ASTIC performs better than both the space-time diversity combining maximal ratio combiner (MRC) and the single-antenna adaptive interference canceller in a multipath fading channel. Also, the efficiency of the C-ASTIC in the multimedia communication environment is investigated under the multiuser, multi-transmit antenna, and multirate WCDMA system in a multipath fading channel. From the results, the C-ASTIC was validated to be useful for multi-rate WCDMA system through improving the performance gain by more than 3 dB at BER of 10
-3/ in a half or more loaded system.
Probability Models of W-CDMA Signals in Realistic Wideband Multipath Channels
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 308~315
This paper proposes new probability models for wideband code division multiple access (W-CDMA) signals. The performance of a W-CDMA system is evaluated by calculating the average bit error rate(BER) which is derived from the probability distribution of the W-CDMA receiver output. If a probability model of the receiver output is available, the performance evaluation becomes much simpler and it enables diverse analyses of the system for channel coding and other purposes. In this paper, probability distributions of W-CDMA signals, more specifically those of the receiver output, are represented as Rayleigh and noncentral chi distribution, considering various bandwidths and channel environments. The adequacy of a probability model is verified by chi-square test of 1% significance level. The BER of the system obtained from the simulation results is compared to that obtained from the probability model to demonstrate the usefulness of the proposed models.
Performance analysis of a call control scheme with buffering and dynamic bandwidth assignment for non-uniform traffic distribution
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 316~323
In this paper, we analyze the call control scheme that is using buffer at new call and handoff call for non-uniform traffic load distribution, the multiple cell environments and the multiple types of services such as voice and data service. Considering the facts, the call admission control method using the effective bandwidth concept is employed in this paper, The bandwidth for a new call and a handoff call is allocated by the number of mobile station and dynamically assigned by taking account of the blocking rate of new calls and the dropping rate of handoff calls. The call control procedure is experimented through a simulation study by dynamically the bandwidth to new and handoff calls based on the blocking rate and the dropping rate. The results show our call control scheme can get a good quality of service for mobile users.
Multiuser Detection Combined with Soft Limiter in FH/MFSK System
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 324~330
In this paper, we proposed a simple modification on Fiebig's REC algorithm for multiuser detection of FH/MFSK systems replacing hard limiter with soft limiter. The performance improvement of our modified REC algorithm has been confirmed with computer simulations. for the parameter of interest, the capacity could be increased about 5% or more without degrading the reliability.
Dynamic Orbit Determination for Geostationary Satellite Broadcasting of Highly Accurate Standard Frequency/Time Signal
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 331~337
In this paper we propose extended Kalman filter (EKF)-trilateration method which associates EKF to conventional radiolocation technique, trilateration in order to improve the accuracy of dynamic orbit determination of geostationary satellite for broadcasting of highly accurate Standard Time/Frequency Signal (STFS). We then compare to analyze the time accuracies of three techniques which are differential mode, trilateration locating one of four calibrated earth stations on a neighboring country, and domestic-only baseline EKF-trilateration. Computer simulations have shown that in spite of domestic-only baseline EKF-trilateration of poor GDOP, it is possible to track and locate satellite with an accuracy of a few hundred meter which is the performance 10 times more accurate than trilateration can provide. Finally we can provide standard time service with the time accuracy better than a few ns (frequency stability : 10
-14/ over 7 days) all around Korea peninsula.
Chernoff Bound and the Refined Large Deviation Approximation for Connection Admission Control in CDMA Systems
Yeong Min Jang ;
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 338~344
This paper proposes a transient (predictive) connection admission control (CAC) scheme using the transient quality of service (QoS) measure for CDMA cellular systems with bursts On-Off sources. We need an approximate and bounded approach for real-time CAC applications. We derive the transient outage probability as the QoS measure using the Chernoff bound and the refuted large deviation approximation. Numerical results show that the predictive CAC is a promising approach for the multicell CDMA systems.
Efficient Performance Evaluation Method for IS-95 System
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 345~352
In this paper, in order to evaluate the performance of IS-95 system reverse link in white gaussian noise and rayleigh fading environment, we suggest epochal proposal to improve computer run-time and its efficiency is verified in terms of the number of samples. MC(Monte Carlo) simulation is the most popular simulation technique lately, but MC simulation requires a number of samples at low bit error rate. Therefore, MC cannot avoid the limit of computer run-time. To alleviate these problems, we apply the suggested method called central moment technique to the reverse link of the IS-95 system and can obtain discrete probability mass functions from Nth order central moments of the less number of received signal samples than those required in MC. Continuous cumulative probability distribution function can be accurately estimated by using interpolation and the improvement effect for the number of samples is proven.
Opto-Digital Implementation of Convergence-Controlled Stereo Target Tracking System
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 353~364
In this paper, a new onto-digital stereo object-tracking system using hierarchical digital algorithms and optical BPEJTC is proposed. This proposed system can adaptively track a moving target by controlling the convergence of stereo camera. firstly, the target is detected through the background matching of the sequential input images by using optical BPEJTC and then the target area is segmented by using the target projection mask which is composed by hierarchical digital processing of image subtraction, logical operation and morphological filtering. Secondly, the location's coordinate of the moving target object for each of the sequential input frames can be extracted through carrying out optical BPEJTC between the reference image of the target region mask and the stereo input image. Finally, the convergence and pan/tilt of stereo camera can be sequentially controlled by using these target coordinate values and the target can be kept in tracking. Also, a possibility of real-time implementation of the adaptive stereo object tracking system is suggested through optically implementing the proposed target extraction and convergence control algorithms.
AlGaAs/InGaAs/GaAs PHEMT power PHEMT with a 0.2
gate length for MIMIC power amplifier.
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 365~371
In this paper, the fabricated power PHEMT devices for millimeter-wave that is below a gate-length of 0.2
using electronic beam lithography technologies, and the DC and frequency characteristics and an output power characteristics were Measured at the various bias conditions. The unit process that is used in PHEMT's manufacture used that low-resistance ohmic contact, air-bridge and back-side lapping process technologies, and so on. The fabricated power PHEMT have an S521 gain of 4 dB and a maximum transconductance(gm) of 317 mS/mm, an unilateral current gain(fT) of 62 GHz, a maximum oscillation frequency(fmax) of 120 GHz at 35 GHz, and a maximum power output(Pmax) of 16 dBm, a power gain(GP) of 4 dB and a drain efficiency(DE) of 35.5 %.
A Study on Narrow-Band Dual-Mode Channel Filter and Equalizer for Ku band Satellite Transponder
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 372~378
In this paper, a narrow-band waveguide channel fitter has been designed and realized for Ku band satellite transponder. Group-delay and amplitude variations of the channel filter have been minimized using a 2-pole reflection type equalizer. The channel filter has been designed to have the 8-pole elliptic response for high frequency selectivity. Dual-mode technique has been adopted for reducing mass and volume of the channel filter and equalizer. The channel filter and equalizer have shown good performance for satellite transponder.
Analysis of Transient Scattering from 3-Dimensional Arbitrarily Shaped Conducting Structures Using Magnetic Field Integral Equation
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 379~387
In this paper, we present a procedure to obtain the transient scattering response from three-dimensional arbitrarily shaped and closed conducting bodies using time-domain magnetic field integral equation (TD-MFIE) with triangular patch functions. This approach results in accurate and comparably stable transient responses from conducting scatterers. Detailed mathematical steps are included, and several numerical results are presented and compared with results from a time-domain electric field integral equation (TD-EFIE) and the inverse courier transform solution of the frequency domain results.
Design and Fabrication of Aperture-Coupled Microstrip Patch Antenna for WLL Repeater Using Space Diversity
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 388~396
In this paper, An aperture-coupled microstrip patch antenna operating at WLL frequency range(Rx : 2.3∼2.33Ghz, Tx : 2.37 ∼2.4Ghz) for WLL repeater is designed and fabricated. FR-4 epoxy substrate with 4.7 relative permittivity is inserted between feed-line and patch plane. Aperture-coupled structure is employed for consideration of bandwidth improvement and gain\`s characteristics. Air gap is arranged at each layer for bandwidth extension and radome is used as a protector in the upper patch. In this paper, both 1 port and 2 port are designed as 1
2 array antenna which uses T-junction and λ
g//4 transformer. Here, 1 port is used as transmitting/receiving antenna and 2 port is used as receiving antenna. Functionally independent two antennas using space diversity arrange slots between two antennas in order to be placed at the same place. As a result, we obtained a excellent isolation below -40dB and return loss is reduced by means of slots arrangement between patch and antenna.
IFSAR, Azimuth Aliasing Resolution, and Interferogram Generation Algorithms
The Journal of Korean Institute of Communications and Information Sciences, volume 27, issue 4B, 2002, Pages 397~402
The IFSAR technique using SAR data has various applications and is the only latest technology to produce high precision height information from the radar phase data. This paper describes the whole implementation algorithm of IFSAR technique. Also it suggests the algorithms for azimuth aliasing resolution and interferogram generation of SAR data. Those are proved through the experiment: azimuth aliasing is resolved and interferogram is generated properly. Therefore, it proposes the method for interferogram generation, an essential process in extracting high precision height data, and the development approach to principal modules of IFSAR algorithm.