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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 30, Issue 12C - Dec 2005
Volume 30, Issue 12B - Dec 2005
Volume 30, Issue 12A - Dec 2005
Volume 30, Issue 11C - Nov 2005
Volume 30, Issue 11B - Nov 2005
Volume 30, Issue 11A - Nov 2005
Volume 30, Issue 10C - Oct 2005
Volume 30, Issue 10B - Oct 2005
Volume 30, Issue 10A - Oct 2005
Volume 30, Issue 9C - Sep 2005
Volume 30, Issue 9B - Sep 2005
Volume 30, Issue 9A - Sep 2005
Volume 30, Issue 8C - Aug 2005
Volume 30, Issue 8B - Aug 2005
Volume 30, Issue 8A - Aug 2005
Volume 30, Issue 7C - Jul 2005
Volume 30, Issue 7B - Jul 2005
Volume 30, Issue 7A - Jul 2005
Volume 30, Issue 6C - Jun 2005
Volume 30, Issue 6B - Jun 2005
Volume 30, Issue 6A - Jun 2005
Volume 30, Issue 5C - May 2005
Volume 30, Issue 5B - May 2005
Volume 30, Issue 5A - May 2005
Volume 30, Issue 4C - Apr 2005
Volume 30, Issue 4B - Apr 2005
Volume 30, Issue 4A - Apr 2005
Volume 30, Issue 3C - Mar 2005
Volume 30, Issue 3B - Mar 2005
Volume 30, Issue 3A - Mar 2005
Volume 30, Issue 2C - Feb 2005
Volume 30, Issue 2B - Feb 2005
Volume 30, Issue 2A - Feb 2005
Volume 30, Issue 1C - Jan 2005
Volume 30, Issue 1B - Jan 2005
Volume 30, Issue 1A - Jan 2005
Selecting the target year
A fast transient control of EDPA gain on channel add/drop WDM networks
Park Jungmoon ; Lee Sangheon ; Shin Seoyong ; Song Seongho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 233~240
In this paper, we have shown the gain recovery time of erbium-doped fiber amplifier(EDFA) in WDM add/drop networks can be reduced to less than
sec by employing disturbance observer technique with PID controller which is based on 3-level EBFA model. The
sec transient time is the fastest one ever reported and it is about
sec previously obtained from disturbance observer technique with PI controller which was based on 2-level EDFA model and it is also less than
sec of commercially available EDFAs for WDM networks. We were able to obtain this result by analyzing various system characteristics as we change the parameters of disturbance observer and PID controller. If this result is applied to a commercial product, the product will do an important role in the future dynamic WDM networks.
LSP Congestion Control methods in ATM based MPLS on BcN
Kim Chul soo ; Park Na jung ; Ahn Gwi im ; Lee Jung tae ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 241~249
ATM based MPLS(Multiprotocol Label Switching) is discussed for its provisioning QOS commitment capabilities, Traffic engineering and smooth migration for BcN in Korea. At this time, due to the comprehensive nature of ATM protocol, ATM has been adapted as the backbone system for carrying Internet traffic[1,2,3,4]. This paper presents preventive congestion control mechanisms for detecting HTR(Hard-To-Reach) LSP(Label Switched Path) in ATM based MPLS systems. In particular, we have introduced a HTR LSP detection method using network signaling information in an ATM layer. MPLS related studies can cover LSP failures in a physical layer fault, it can not impact network congestion status. Here we will present the research results for introducing HTR LSP detection methods and control mechanisms and this mechanism can be implementing as SOC for high speed processing a packet header. We concluded that it showed faster congestion avoidance abilities with a more reduced system load and maximized the efficiency of network resources by restricting ineffective machine attempts.
Robust Frequency Offset Estimation with a Single Symbol for FH-OFDMA
Yoon Dae jung ; Han Dong seog ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 250~258
An initial carrier frequency offset estimation algorithm is proposed for a multi-user frequency bowing orthogonal frequency division modulation-frequency division multiple access (FH-OFDMA) system with a single preamble symbol. To mitigate the effect of the frequency offset, every mobile station needs to accurately and rapidly acquire synchronization. The proposed algorithm uses only one preamble symbol in which two kinds of subcarriers are designed for coarse and fine frequency offset estimation. The non-data aided estimation using the energy spectrum is exploited for fine offset estimation, and maximum likelihood estimation using correlation for coarse offset estimation. By combining the two estimation results, an accurate frequency offset can be estimated with a single symbol. Through simulations, the performance of the proposed algorithm is evaluated by comparing estimation error variance with a conventional method.
A Mathematical Model for Asymmetrical/Heterogeneous Traffic Management in TD-CDMA System
Shin Jung chae ; Lee Yutae ; Kim Jeong ho ; Cho Ho shin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 259~270
This paper proposes a mathematical model to analyze call-and packet-level performance of the TD-CDMA/TDD system which could serve a flexible radio resource management against multi-type heterogeneous and asymmetrical traffic conditions. On call-level analysis, the mathematical model based on queueing theory performs multi-dimensional operations using random vectors or matrices to consider multiple types of traffic and also deal with asymmetrical up- and down-direction transmissions separately. Employing the mathematical model, we obtain rail blocking probability for each type of traffic and also the optimum switching-point with the smallest call flocking probability. And on packet-level analysis, employing a non-prioritized queueing scheme between circuit and packet calls, we solve 2-dimensional random vector problem composed of the queue length for packets and the number of circuit calls being served. Finally, packet-level performance is analyzed in terms of the packet loss probability and the buffer size required under mixed-traffic conditions of multiple types of circuit and packet calls.
Downlink Parallel Transmit Power Control Algorithm during Soft handover for WCDMA System
Han Young ok ; Seo kyung Jin ; Park Sung kwon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 271~281
This paper for establishing the reliability of the TPC command is introduced, where the soft symbol of the TPC command itself is directed used as a reliability indicator. In addition to the new reliability estimation, the concept of parallel use of TPC algorithms is presented. The results show that the soft symbol reliability estimation decrease the
levels with 0.3 dB, thus providing a useful capacity gain. The parallel use of 2 to 4 algorithms is also shown to decrease the sensitivity of the algorithms to the algorithm thresholds used, and thus increase the feasibility of the algorithms in a real world networks.
Decoding Performance of Quasi-Orthogonal Space Time Block Code Using Optimal Transmit Power Allocation
Choe Kwang don ; Kim Bong joon ; Cho Young ha ; Park Sang kyu ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 282~287
The space time block code(STBC) can not provide simultaneously both full diversity and full transmission rate in a transmit diversity system having more than two transmit antennas.. There are a quasi orthogonal STBC for four transmit antennas that provides full transmission rate and minimized interference. Recently, a simple correlation canceling algorithm is introduced to achieve full diversity from STBC considering four transmit antennas. In this paper, we propose a new decoding procedure using the power allocation at the transmitter and subtraction interference process at the receiver to achieve a better performance without noise enhancement.
An SLM-Based Real-time PAPR Reduction method using Dummy Sequence Insertion in the OFDM Communication System
Ryu Heung-Gyoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 288~295
OFDM communications system is very attractive for the high data rate wireless transmission. However, it may be distorted in the nonlinear HPA since OFDM signal has high PAPR. So, a new SLM method using dummy sequence is studied for reducing the PAPR, and we call it DSI-SLM method. Unlike the conventional SLM method using the phase rotation, dummy sequences for PAPR reduction are assigned at the predefined sub-carriers. After IFFT, the OFDM data signal of the lowest PAPR is selected to transmit. So, it can cut down the computational complexity because it does not require the transmission and demodulation process of side information about the phase rotation. This proposed method can solve the time delay problem so that PAPR reduction can be made in real time processing.
Performance Evaluation of a Cellular OFDM System with Heterogeneous MIMO Users
Oh Joon ; Hwang Hyeon chyeol ; Lim Jong kyoung ; Kim Duk kyung ; Kwak Kyung sup ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 296~303
In this paper, we evaluate system performance and propose signal separation and detection when a user with one antenna shares the co-channel together with a user with two space-time coded antennas. The proposed technique can identify co-channel users by an interference cancellation method and detect the signals by maximum likelihood method. Simulation results show that the shortcoming of the Minimum Mean-Squared Error technique which can be applied two users with the same number of antenna but can not applied for heterogeneous MIMO users with the different number of antennas. Also, we apply the proposed scheme to OFDM system and evaluate the system performance. By simulations, we identify that the performance of the proposed system is the same as that of the existing single antenna users and improves the performance of the two-antenna MIMO users.
Distributed OCSP Certificate Verification Model for Reducing Response Time
Choi Seung kwon ; Jang Yoon sik ; Ji Hong il ; Shin Seung soo ; Cho Yong hwan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 304~311
OCSP has specific characters which can suspend, close, and correct in real time. But, as more clients use the OCSP server verification, more updated information is needed, which can lead to jamming in the OCSP server. To apply this technique of Distributed OCSP server so as to reduce the certificate verification OCSP from jamming. Also, the Distributed OCSP server will solve the problems of the intensive central structure. Simulation results show that the average reply time of certificate verification request and server load are reduced in the case using distributed OCSP. In addition to this advantage, resource distribution and fault tolerance are acquired because of multiple OCSP.
Design and Fabrication of Bow-tie-shaped Meander Microstrip Patch Antenna on 5GHz Application
Kwak Sang hun ; Yoon Joong han ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 312~319
In this paper, a meander-type microstrip patch antenna for application in 5GHz-band is designed and fabricated. To obtain enough bandwidth in VSWR<2, the foam is inserted between substrate and ground plane, the coaxial probe source is used. Antenna is simulated varing the length and width of meander line, the position of probe feeding and the thick of airgap. Later anterlna is fabricated with optimizated antenna parameter. The measured result of Fabricated antenna obtained
bandwidth in VSWR<2$, the gain of
dBi, Unidirectional pattern.
CPW Directional Couplers with T-Shaped Slots
Park Jeong boon ; Lee Chang on ; Choi Kyung min ; Shin Chull chai ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 320~327
In this paper, compensation structures are proposed in the CPW directional couplers with finite-extent backed conductor for tight coupling. The proposed structures are realized T-shaped expanded slots and modified finite-extent backed conductor in CPW coupled structure. The T-shaped expanded slots was used to avoide reduced coupling and modified finite extent backed conductor of dumbbell shape was used to enhance directivity and matching. The designed CPW directional couplers at 1 GHz has good directivity without reducing coupling in simulation by EM solver based on full-wave analysis and measurements.
SRAM Reuse Design and Verification by Redundancy Memory
Shim Eun sung ; Chang Hoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 328~335
bIn this paper, built-in self-repair(BISR) is proposed for semiconductor memories. BISR is consisted of BIST(Buit-in self-test) and BIRU(Built-In Remapping Uint). BIST circuits are required not oがy to detect the presence of faults but also to specify their locations for repair. The memory rows are virtually divided into row blocks and reconfiguration is performed at the row block level instead of the traditional row level. According to the experimental result, we can verify algorithm for replacement of faulty cell.
Bit-serial Discrete Wavelet Transform Filter Design
Park Tae geun ; Kim Ju young ; Noh Jun rye ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 336~344
Discrete Wavelet Transform(DWT) is the oncoming generation of compression technique that has been selected for MPEG4 and JEPG2000, because it has no blocking effects and efficiently determines frequency property of temporary time. In this paper, we propose an efficient bit-serial architecture for the low-power and low-complexity DWT filter, employing two-channel QMF(Qudracture Mirror Filter) PR(Perfect Reconstruction) lattice filter. The filter consists of four lattices(filter length=8) and we determine the quantization bit for the coefficients by the fixed-length PSNR(peak-signal-to-noise ratio) analysis and propose the architecture of the bit-serial multiplier with the fixed coefficient. The CSD encoding for the coefficients is adopted to minimize the number of non-zero bits, thus reduces the hardware complexity. The proposed folded 1D DWT architecture processes the other resolution levels during idle periods by decimations and its efficient scheduling is proposed. The proposed architecture requires only flip-flops and full-adders. The proposed architecture has been designed and verified by VerilogHDL and synthesized by Synopsys Design Compiler with a Hynix 0.35
m STD cell library. The maximum operating frequency is 200MHz and the throughput is 175Mbps with 16 clock latencies.
A Design on the Extended ATA Interface for Multimedia Systems
Ku Dae sung ; Kim Jong bin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 345~349
In this paper, the enhanced ATA(AT Attachment Interface with Extension) interface that combines the price of ATA and intelligent operation of SCSI(Small Computer System Interface) is realized both performance and structure of general interface used to connect peripheral devices that are used in PC(Personal Computer). SCSI bus is for peripheral devices that have intelligent operation. It is excellent bus that has well-arranged command system and stable hardware structure. But is aspect of price this peripheral device has the difficulty in purchase because there is price difference more than two times compared with ATA peripheral device. Whereas, although ATA peripheral device had low performance in the early period, after the improvement its speed has almost etched to SCSI and its price is also excellent. In this paper, the enhanced interface structure to fulfill price and performance was suggested and materialized as the hardware using such two advantages.
A 5.8 GHz SiGe Up-Conversion Mixer with On-Chip Active Baluns for DSRC Transmitter
Lee Sang heung ; Lee Ja yol ; Kim Sang hoon ; Bae Hyun cheol ; Kang Jin yeong ; Kim Bo woo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 30, issue 4A, 2005, Pages 350~357
DSRC provides high speed radio link between Road Side Equipment and On-Board Equipment within the narrow communication area. In this paper, a 5.8 GHz up-conversion mixer for DSRC communication system was designed and fabricated using 0.8 m SiGe HBT process technology and IF/LO/RF matching circuits, IF/LO input balun circuits, and RP output balun circuit were all integrated on chip. The chip size of fabricated mixer was
and the measured performance was 3.5 dB conversion gain, -12.5 dBm output IP3, 42 dB LO to If isolation, 38 dB LO to RF isolation, current consumption of 29 mA for 3.0 V supply voltage.