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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 26, Issue 12C - Dec 2001
Volume 26, Issue 12B - Dec 2001
Volume 26, Issue 12A - Dec 2001
Volume 26, Issue 11C - Nov 2001
Volume 26, Issue 11B - Nov 2001
Volume 26, Issue 11A - Nov 2001
Volume 26, Issue 10B - Oct 2001
Volume 26, Issue 10A - Oct 2001
Volume 26, Issue 9B - Sep 2001
Volume 26, Issue 9A - Sep 2001
Volume 26, Issue 8B - Aug 2001
Volume 26, Issue 8A - Aug 2001
Volume 26, Issue 7B - Jul 2001
Volume 26, Issue 7A - Jul 2001
Volume 26, Issue 6B - Jun 2001
Volume 26, Issue 6A - Jun 2001
Volume 26, Issue 5B - May 2001
Volume 26, Issue 5A - May 2001
Volume 26, Issue 4B - Apr 2001
Volume 26, Issue 3B - Mar 2001
Selecting the target year
A Study on the Access Network Using CDMA-PON
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1629~1636
A CDMA-PON system is proposed to be used for the optical access network which is becoming indispensable to keep up with the subscriber\`s uprising data traffic. CDMA technique is efficiently used not just to deliver multiple channels to each remote unit, but also to suppress the optical beat noise. In this study, multiple beat noises environments was analysed, modulation schemes for both forward and reverse links were suggested and a simulation and basic experiment for multiple channels was performed successfully.
Performance Evaluation of Multi-Phased MC-CD74A System for transmitting the High Rate Data
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1637~1647
Multi-Code CDMA (MC-CDMA) can not only be integrated easily with a conventional system, but also achieve good spectral efficiency and high processing gain. However, it suffers from high value of peak-to-average power ratio (PAPR). In this paper, we propose the Multi-Phase CDMA (MP-CDMA) system that can provide variable rate service and is not susceptible to the non-linear characteristics of amplifier. The clipping is introduced between at the output of multi-code modulator and at the input of MPSK modulator in order to improve the performance of MPSK chip demodulator and reduce the system complexity, The system performances are compared for the different Number of codes and different clipping levels, respectively. The optimum clipping level is also evaluated for the different number of codes in both, AWGN and frequency flat fading channel.
Performance Analysis of TD-CDMA Systems with Cell Synchronization Error
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1648~1655
TD-CDMA is based on a combination of CDMA, TDMA, and TDD technologies, and it is proposed to support TDD mode for IMT-2000 service. To analyze the performance of TD-CDMA, we have to establish a modeling technique that takes into account the interference that can occur in each scheme. There is special interference in TDD mode, e.g. interference from base station to base station and from mobile to mobile. In this paper, we present an interference model for analyzing the performance of TD-CDMA systems and the slot allocation strategies. This model includes the cell synchronization error. As a result, this paper shows that almost equal slot allocation and low cell synchronization error guarantee desirable performance in TD-CDMA
An Enhanced Wireless TCP protocol based on Explicit Error Notification
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1656~1664
When a packet loss occurs in a communication network operating a TCP protocol, the TCP protocol regards it that the loss has resulted from network congestion. Then the TCP protocol performs congestion control. When it is applied to the wireless network having quite a high BER characteristics, the performance of TCP protocol is degraded very much. In this paper, we propose an Explicit Error Notification(EEN) algorithm to improve the performance of the wireless TCP When a packet loss occurs in the wireless network, the TCP receiver decodes the TCP segment sequence number and the address of the TCP sender and receiver, and then informs the TCP sender of the error in wireless network by sending a NACK. It is to distinguish packets in error from losses of network congestion. In this paper, the performance of the proposed EEN algorithm is analyzed and simulated. In fact, as more errors are corrected, the proposed algorithm shows a larger
The Effect of Spreading Gain Control on a CDMA Slotted ALOHA System
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1665~1676
The effect of spreading gain control on the throughput of a CDMA slotted ALOHA system is considered. Mobile users transmit packets over a shared channel, and the packets transmitted in the same time slot over the shared channel act as simultaneous access interference (SAI). When using spread-spectrum signal, a CDMA slotted ALOHA channel achieves high probability of capture due to the property of high title resolution, and the bit rate of user information is determined by spreading gain. When the SAI level gets larger, the high value of spreading gain enhances the packet throughput by increasing the probability of a successful packet transmission, while it degrades the of the effective throughput by reducing the user information bits carried within a packer. To solve the problem, we investigated the effect of the capture probability and the SAI level on these system throughputs, and evaluated the throughput performance of the system for each spreading gain control scheme. The results showed that the maximum effective throughput could be achieved with an unified method despite the variation of the SAI level by deriving an optimal value of the spreading gain according to 171e system states.
A Study on the Estimation of the Call Drop Rate for Call Admission Control in DS-CDMA Reverse Link
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1677~1685
In this paper, we propose a call admission control scheme that can be performed within guaranteeing of required QoS(Quality of Services) in DS-CDMA(Direct Sequence-Code Division Multiple Access) reverse link. It has been performed rely on a physical channel numberonly and based on quality of received signal from MODEM(modulator/demodulator) part in established study. In other methods, the standard for services would have been set from statistical analysis of users\` location and using received power level in BTS(Base Transceiver Station). These ways bring about not only system loads but time delay or great differences from real environment. To solve these problems, we propose a call drop rate estimation algorithm for the purpose of call admission control based on measured value at LNA(Low Noise Amplifier) ports of BTS(Base Transceiver Station) in real time. This method proposed in this paper estimates a quality of offered service in real time, reduce system loads and shorten time delay which is needed to determine the standard for call admission control. But it requires a additional 17W complexity which can measure received signal power in BTS and estimate call drop rate.
Capacity of Spectrum Sharing Scheme for Reverse/Forward Link in Hierachical CDMA Cellular Systems with Hot-Spot Microcell
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1686~1694
In this paper, we analyze capacities of spectrum sharing scheme for both reverse link and forward link in hierachical CDMA cellular systems with Hot-spot microcell. Capacity analysis is performed through Monte-Carlo simulation by considering microcell radius, location of microcell. and transmission power ratio of microoell to macrocell. From simulation results, we analyzed these effects and derived a general design approach. In addition, the performance of spectrum sharing scheme for each link is analyzed in the capacity plane.
A Design of High Speed Infrared Optical Data Link IC
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1695~1702
This paper describes a design of CMOS infrared (IR) wireless data link IC which can be used in IrDA(Infrared Data Association) application from 4 Mb/s to 100 Mb/s The implemented chip consists of variable gain transimpedance amplifier which has a gain range from 60 dB to 100 dB, AGC (automatic gain control) circuits, AOC(automatic offset control) loop, 4 PPM (pulse position modulation) modulator/demodulator and DLL(delay locked loops). This infrared optical link If was implemented using commercial 0.25 um 1-poly 5-metal CMOS process. The chip consumes 25 mW at 100 Mb/s with 2.5 V supply voltage excluding buffer amplifier. The die area of prototype IC is 1.5 mm
A Study on Characterization of Stimulated Brillouin Scattering in Single-Mode Optical Fiber
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1703~1711
Study on 5.8 GHz DR Duplexer using Cavity Filter
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1712~1723
This paper presents a design procedure and manufacturing techniques realizing of a 5.8 GHz duplexer based on cylindrical coaxial dielectric resonator. Upto Q
o/=30,000 cylindric coaxial dielectric resonator was developed control by addition of dielectric materials. This resonator shows attenuation characteristics -40 dB for transmitter and -50 dB for receiver by consisting of two sets of 4-stage cavity resonator within f
10 MHz bandwidth which was requirement of DSRC. Employing the measurement results, design procedure to characterize the transmission and reflection properties are presented.
A Study on Wideband Microstrip Array Antennas Using the Parallel Coupled Lines
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1724~1732
In this paper, a technique for increasing the bandwidth of microstrip array antennas using the parallel coupled lines on a single layer is presented. Four types of wideband microstrip array antenna are designed and the characteristics of each type are analyzed. In addition, an iterative method using a distributed network is proposed to design the parallel coupled lines as a wideband impedance matching network. Measurements show that the proposed antennas provide wider bandwidths ∼1.7 times those of conventional microstirp array antennas, while the sizes of proposed antennal are the same as that of a conventional array. And low cross-polarization level can be obtained through symmetrical locations of the parallel coupled lines section
A Monolithic 5 GHz Image Reject Mixer for Wireless LAN applications
Ho-Young Kim ; Jae-Hyun Cho ; Jung-Ho Park ;
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1733~1740
A monolithic 5 GHz image reject mixer using a 0.5-m GaAs MESFET technology is designed and simulated. The Mixer exhibits a 13.56 dB down-conversion gain, a SSB (Single SideBand) noise figure of 11.91 dB, an input IP3 (third order intercept point) of -3.73 dBm and a PldB (1-dB compression point) of -11.0 dBm. The critical issue in the image reject mixer is the phase accuracy and magnitude balance of the 90 phase shifting network. The proposed image reject mixer realizes a 90 phase shifter on chip. This phase shifting network does not need any phase adjusting to achieve the phase error specification of 3 over a frequency range from 800 MHz to 1GHz. The simulated overall image rejection ratio is better than 50 dB.
OFDM SYSTEM USING CROSS-HANDED CIRCULAR POLARIZAT10N
Kim, Byung-Ok ; Ha, Deock-Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1741~1746
This paper proposes the OFDM system that uses circularly polarized waves for improving the system performance. The circular polarization has the characteristic that it cannot receive the waves which are reflected by odd times. Using this characteristic, a modified OFDM system that uses the cross-handed circular polarization(XCP-OFDM) is newly proposed. By using the characteristic of circular polarization, it is clearly seen that the system performance of XCP-OFDM can be improved to a great extent. This is due to a reduction of the interferences caused by reflected waves and inter-channel interference. Both theoretical analysis and system simulation results are described.
Design and Fabrication of SMD Type Wilkinson Power Divider for PCS Basestation
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1747~1753
This paper describe the design and fabrication of a SMD type Wilkinson power divider for PCS basestation. It has been designed for commercial power amplifier system by HP-ADS and fabricated with the size 0.56
0.35 inches. As a result, the power divider was well-operated in the frequency ranges of 1.75 ∼ 1.98GHz for the application of PCS system. The power divider reveals insertion loss 0.2dB, isolation -19.8dB, amplitude balance 0.02dB, phase balance 0.5o, input and output impedance matching -20.6dB respectively.
Design and Fabrication of Amplifier Using Photonic Bandgap and Coplanar Waveguide
The Journal of Korean Institute of Communications and Information Sciences, volume 26, issue 12B, 2001, Pages 1754~1757
In this paper, a R-band hybrid amplifier with the coplanar waveguide(CPW) and the photonic bandgap(PBG) structure is designed and fabricated. The PBG and the CPW techniques are simultaneously employed in amplifier to improve the power added efficiency(PAE) and the IMD(Intermodulation Distortion) in R-band. In this paper, the PBG structures are optimized to obtain matching network. The output impedance of amplifier and the input impedance of PBG are matched to minimize the return loss. The PAE and the IMD were improved 15% and 4.5dB compared with the conventional amplifier, respectively.