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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 29, Issue 12C - Dec 2004
Volume 29, Issue 12B - Dec 2004
Volume 29, Issue 12A - Dec 2004
Volume 29, Issue 11C - Nov 2004
Volume 29, Issue 11B - Nov 2004
Volume 29, Issue 11A - Nov 2004
Volume 29, Issue 10C - Oct 2004
Volume 29, Issue 10B - Oct 2004
Volume 29, Issue 10A - Oct 2004
Volume 29, Issue 9C - Sep 2004
Volume 29, Issue 9B - Sep 2004
Volume 29, Issue 9A - Sep 2004
Volume 29, Issue 8C - Aug 2004
Volume 29, Issue 8B - Aug 2004
Volume 29, Issue 8A - Aug 2004
Volume 29, Issue 7C - Jul 2004
Volume 29, Issue 7B - Jul 2004
Volume 29, Issue 7A - Jul 2004
Volume 29, Issue 6C - Jun 2004
Volume 29, Issue 6B - Jun 2004
Volume 29, Issue 6A - Jun 2004
Volume 29, Issue 5C - May 2004
Volume 29, Issue 5B - May 2004
Volume 29, Issue 5A - May 2004
Volume 29, Issue 4C - Apr 2004
Volume 29, Issue 4B - Apr 2004
Volume 29, Issue 4A - Apr 2004
Volume 29, Issue 3C - Mar 2004
Volume 29, Issue 3B - Mar 2004
Volume 29, Issue 3A - Mar 2004
Volume 29, Issue 2C - Feb 2004
Volume 29, Issue 2B - Feb 2004
Volume 29, Issue 2A - Feb 2004
Volume 29, Issue 1C - Jan 2004
Volume 29, Issue 1B - Jan 2004
Volume 29, Issue 1A - Jan 2004
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Calculation of Pump Light Power in Wideband Optical Phase Conjugator with Highly-Nonlinear Dispersion Shifted fiber
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 473~483
In this paper, we numerically investigated the optimum pump light power best compensating for pulse distortion due to both chromatic dispersion and self phase modulation (SPM) as a function of channel input power in 8 channel
40 Gbps wavelength division multiplexing (WDM systems. Also we investigated the allowable maximum channel input power dependence on modulation format and fiber dispersion coefficient in the various pump light power of OPC. The considered WDM transmission system is based on path-averaged intensity approximation (PAIA) mid-span spectral inversion (MSSI) compensation method, which has highly-nonlinear dispersion shifted fiber (HNL-SDF) as nonlinear medium of optical phase conjugator (OPC) in the mid-way of total transmission line. We confirmed that optimal pump light power of HNL-DSF OPC depend on modulation format, initial channel input power, total transmission length and fiber dispersion. But optimal pump light power of HNL-DSF OPC must be selected to make power conversion ratio to almost unity. And we confirmed that, if we allow a 1 dB eye opening penalty (EOP), the tolerable maximum channel input power is increased by using RZ than NRZ as modulation format when pump light power of HNL-DSF OPC is not optimal value but another values.
Pump Effect by Injected C-band laser in L-band EDFA
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 484~491
C-band pumping effect appears in L-band EDFA because the absorption in C-band occurs dominant under the condition of such a low average population inversion. In this paper, we show how the C-band pumping effect depends on 980nm pump power, the C-band wavelength, and its input power. The C-band pumping is caused by absorbing C-band injection or backward spontaneous emission power through EDF. If the same small signal condition is given by a C-band pump, the C-band pump of a long wavelength is good for the saturation and noise characteristics of L-band signal. Finally, it is considered that in the aspect of saturation characteristics, C-band compensation is not so much efficient as L-band in Gain-Clamped L-band EDFA having a lossy resonator.
Channel Estimation and Adaptive Channel Coding Technique for Video Transmission
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 492~501
The performance of mobile communication systems depends on the state of the time-varying multi-path fading channel. To effectively prevent the corruption of video stream and its propagation in spatial and temporal domain, proactive error controls are widely being deployed. Among possible candidates, the rate compatible punctured convolutional (RCPC) code has been widely used for multimedia data, since its rate can be determined flexibly. In this paper, the adaptive channel estimation and the adaptive error correction techniques over the time-varying mobile channel have been proposed. Extensive computer simulations show that the proposed techniques yield the superior performance than the fixed rate system.
Symbol Synchronization of OFDM Systems using Signs of Preamble Signals
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 502~513
This paper proposes a symbol synchronization method in the IEEE 802.11a wireless OPDM system, which uses only signs of the in-phase and the quadrature signals in the short preamble. The short preamble is sampled with 2 tines of Nyquist sampling rate and both of the autocorrelation and the cross-relation are used in the proposed method. This method has some advantages that the ACG (Automatic Gain Control) can be processed concurrently during the short preamble and its implementation is not much complicated. The proposed symbol synchronization method is verified through simulations on frequency offset, multi-path and white Gaussian noise.
All-Optical WDM Buffer System realized by NOLM and Feedback Loop
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 514~520
In WDM networt a WDM buffer is one of essential elements for realizing all-optical packet switching system. In this paper, we propose and demonstrate a single loop type all-optical WDM buffer system. The proposed one consists of NOLM and feedback loop, and provides more than 40 turns buffering (more than 20
) for single input pulse (1550nm, width: 20㎱) before selected by control signal pulse (1553nm, width: 30㎱).
Peformance Analysis of a Pre-Scrambling Scheme for Reducing the PAPR in OFDM Systems
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 521~526
OFDM is a very attractive technique for achieving high-bit-rate data transmission and high spectrum efficiency. However, one of disadvantages of OFDM signal is the high PAPR characteristic when multi-carriers are added up coherently. In this Paper, we propose-scrambling scheme using correlator for PAPR reduction and reducing the amount of PAPR calculations. The simulation results show that this scheme has less computational complexity and reasonable PAPR reduction capability compared to PTS technique.
Hybrid TDMA and Binary CDMA System
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 527~536
A novel hybrid multiple access system, TD-BCDMA, where Binary CDMA that maintains a constant amplitude by clipping the summation of input signals multiplied by the orthogonal codes is transmitted over a TDMA frame structure, was Nosed. In every time slot of TDMA, binary CDMA modulated multiple channel signals are transmitted with the same waveform of TDMA. TD-BCDMA has all the advantages of TDMA. Flexible adjustment of the data transmission rate In demand is possible by adjusting the number of codes and time slots assigned to each user. This property was used to show an example of Ad Hoc network applications. To obtain a proper synchronization scheme for TD-BCDMA, the Receiver Operating Characteristics performance and the false alarm probability and false dismissal probability under various channel environment of two different schemes, a preamble scheme as in TDMA and a synchronization channel scheme as in CDMA were compared. It was proved that the preamble scheme is more practical and suitable than the synchronization channel scheme for the hybrid multiple access system.
A Study on the Performance of DS-CDM-SQAM in Nonlinear Land Mobile Satellite Broadcasting Environments
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 537~544
In this paper, we p개pose DS-CDM-SQAM(Superposed Quadrature Amplitude Modulation) which is characterized by its smooth phase transition and small envelope fluctuation, and improves the power efficiency as compared to DS-CDM-QPSK of satellited-based DMB system(ITR-R BO.1130-4 System E) in a nonlinearly amplified channel. Computer simulation results show that the proposed DS-CDM-SQAM improves Eb/No by 1.7㏈ to maintain BER=1
in nonlinearly amplified multipath mobile radio environments. Therefore, the proposed DS-CDM-SQAM system significantly improves the power efficiency in nonlinear land mobile satellite DMB environments.
A Study on the Memory Saturation Prevention of the Entropy Encoder for He HDTV
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 545~553
Expansion of network environment and multimedia demand universality of application service as HDTV, etc. During these processes, it is essential to process multimedia in real time in the wireless communication system based on mobile phone network and in the wire communication system due to fiber cable and xDSL. So, in this Paper the optimal memory allocation algorithm combines the merit of huffman encoding which is superior in simultaneous decoding ability and lempel-ziv that is distinguished in execution of compress is proposed to improve the channel transmission rate and processing speed in the compressing procedure and is verified in the entropy encoder of HDTV. Because the entropy encoder system using proposed optimal memory allocation algorithm has memory saturation prevention we confirms that the compressing ratio for moving pictures is superior than Huffman encoding and LZW.
Study of Optimization for High Performance Adders
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 554~565
In this paper, we implement single cycle and multi cycle adders. We can compare area and time by using the implemented adders. The size of adders is 64, 128, 256-bits. The architecture of hybrid adders is that the carry-out of small adder groups can be interconnected by utilizing n carry propagate unit. The size of small adder groups is selected in three formats - 4, 8, 16-bits. These adders were implemented with Verilog HDL with top-down methodology, and they were verified by behavioral model. The verified models were synthesized with a Samsung 0,35(um), 3.3(V) CMOS standard cell library while a using Synopsys Design Compiler. All adders were synthesized with group or ungroup. The optimized adder for a Crypto-processor included Smart Card IC is that a 64-bit RCA based on 16-bit CLA. All small adder groups in this optimized adder were synthesized with group. This adder can operate at a clock speed of 198 MHz and has about 961 gates. All adders can execute operations in this won case conditions of 2.7 V, 85
Variable Optical Fiber Attenuator Using Bending-Sensitive Fiber
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 566~573
A variable optical attenuator with a bending-sensitive fiber (BSF) that can be used in optical networks is developed. The proposed BSF consists of inner core, outer core, center dip and cladding. The proposed BSF is also very sensitive to mechanical perturbation, such as bending and pressure, making the light propagating in the BSF easily controlled and attenuated. The fabricated fiber-type variable optical attenuator using the proposed BSF (VOAFB) consisted of the BSF in a rectangular rubber ring with a fixed bend radius (BR) in a steady state. The variable optical attenuator using the proposed BSF (VOAFB) was able to attenuate the optical power by more than about -38㏈ with the gradient -88.4［㏈
/］ at (1540∼1560nm) based m adjusting the mechanical pressure applied to the upper surface of the rectangular rubber ring with the bent BSF. According to the experimental results when using the proposed VOAFB, the optical power was easily controlled by adjusting mechanical pressure and produced an insertion loss of 0.68㏈, polarization loss of 0.5㏈, and return loss of less than -60㏈.
Performance Analysis of Transmission rate Scheduling Schemes for non-real Service in Burst-Switching (DS/CDMA) System
The Journal of Korean Institute of Communications and Information Sciences, volume 29, issue 5A, 2004, Pages 574~582
This paper shows the performance comparisons of several different rate scheduling schemes for non-real time data service over the uplink of burst switching-based direct sequencecode division multiple access (DS/CDMA) system to support the integrated voice/data service. The closed-form solution of optimal scheduling formulation, which minimizes average transmission delay when all of the active data users are transmitting simultaneously, is presented and mathematical analyses with other rate scheduling schemes, which provide efficiency criterion of transmission delay for rate scheduling schemes, are performed. Numerical results show the analyses explicitly.