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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of electromagnetic engineering and science
Journal Basic Information
Journal DOI :
The Korean Institute of Electromagnetic Engineering and Science
Editor in Chief :
Volume & Issues
Volume 6, Issue 4 - Dec 2006
Volume 6, Issue 3 - Sep 2006
Volume 6, Issue 2 - Jun 2006
Volume 6, Issue 1 - Mar 2006
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A 18-Mbp/s, 8-State, High-Speed Turbo Decoder
Jung Ji-Won ; Kim Min-Hyuk ; Jeong Jin-Hee ;
Journal of electromagnetic engineering and science, volume 6, issue 3, 2006, Pages 147~154
In this paper, we propose and present implementation results of a high-speed turbo decoding algorithm. The latency caused by (de) interleaving and iterative decoding in a conventional maximum a posteriori(MAP) turbo decoder can be dramatically reduced with the proposed design. The source of the latency reduction is come from the combination of the radix-4, dual-path processing, parallel decoding, and rearly-stop algorithms. This reduced latency enables the use of the turbo decoder as a forward error correction scheme in real-time wireless communication services. The proposed scheme results in a slight degradation in bit-error rate(BER) performance for large block sizes because the effective interleaver size in a radix-4 implementation is reduced to half, relative to the conventional method. Fixed on the parameters of N=212, iteration=3, 8-states, 3 iterations, and QPSK modulation scheme, we designed the adaptive high-speed turbo decoder using the Xilinx chip (VIRTEX2P (XC2VP30-5FG676)) with the speed of 17.78 Mb/s. From the results, we confirmed that the decoding speed of the proposed decoder is faster than conventional algorithms by 8 times.
An Efficient Filter Design via Optimized Rational-Function Fitting, without Similarity Transformation
Kahng Sung-Tek ;
Journal of electromagnetic engineering and science, volume 6, issue 3, 2006, Pages 155~159
An efficient method is presented to design filters without the similarity transform of their coupling coefficient matrix as circuit parameters, which is very tedious due to pivoting and deciding rotation angles needed during the iterations. The transfer function of a filter is directly used for the design and its desired form is derived by the optimized rational-function fitting technique. A 3rd order coaxial lowpass filter is taken as an example to validate the proposed method.
An Oscillator Incorporating a Planar Helical Resonator for Phase Noise Reduction and Harmonic Suppression
Hwang Cheol-Gyu ; Myung Noh-Hoon ;
Journal of electromagnetic engineering and science, volume 6, issue 3, 2006, Pages 160~164
This paper describes a compact printed helical resonator and its application to a microwave oscillator circuit implemented in coplanar waveguide(CPW) technology. The high Q-factor and spurious-free characteristic of the resonator contribute to the phase noise reduction and the harmonic suppression of the resulting oscillator circuit, respectively. The designed resonator resonating at the frequency of 5.5 GHz showed a loaded Q of 180 in a chip area of only 40 % of the corresponding miniaturized hairpin resonator without any spurious resonances. The fully planar oscillator incorporated with this resonator showed additional phase noise reduction of 10.5 dB at 1 MHz offset and a second harmonic suppression enhancement of 6 dB when compared to those of a conventional CPW oscillator without the planar helical resonator(PHR) structure.
Application of Magneto-Dielectric Materials in Antenna Design
Min Kyeong-Sik ; Tran Viet-Hong ;
Journal of electromagnetic engineering and science, volume 6, issue 3, 2006, Pages 165~170
In this paper, magneto-dielectric material is proposed to use for minimizing antenna size. One examle of very small antenna is presented to prove this with antenna's area of
, and just moderate values of permittivity and permeability while the return loss can reach - 38 dB at the resonant frequency. The parameters of dielectric material for that best performance are
. Besides, this material also has ability to control the trade-off between the gain and bandwidth while keeping the antenna size unchanged.
Semi-Lumped Compact Low-Pass Filter for Harmonics Suppression
Li Rui ; Kim Dong-Il ; Choi Chang-Mook ;
Journal of electromagnetic engineering and science, volume 6, issue 3, 2006, Pages 171~175
In this paper, a new semi-lumped low-pass filter with three finite attenuation poles at stopband is presented. The new structure is composed of a pair of symmetrical parallel coupled-line and a shunted capacitor. With this configuration, three finite attenuation poles can be available for 2nd, 3rd, and 4th harmonics suppression. The research method is based on transmission-line model for tuning the attenuation poles. In order to examine the feasibility of the proposed structure, a low-pass filter based on microstrip structure with harmonics suppression is designed, fabricated, and measured. The experimental results of the fabricated circuit agree well with the simulation and analytical ones.
Performance Analysis of CDMA-OFDM System via Cooperative Communication in Wireless Fading Environment
Jeong Hwi-Jae ; Kong Hyung-Yun ;
Journal of electromagnetic engineering and science, volume 6, issue 3, 2006, Pages 176~181
Signal distortion due to the path loss, shadow, and multi-path fading is very serious in radio channel. In this paper, we propose CDMA-OFDM cooperative communication system based on DFP(Decode and Forward Protocol) to overcome these phenomena using spread spectrum technique, orthogonal sub-carrier, and the space diversity. We simulated proposed system under Rayleigh flat fading channel environment. A variety of simulation results reveal the cooperation can provide performance gain of up to 12 dB over direct communications in ideal inter-user case at BER of
. And we can also confirm variation of diversity effect as channel environment changes.
Derivation and Analysis of the BER Closed Form in the OFDM Communication System with IQ Imbalance
Hieu Nguyen Thanh ; Kang Byung-Su ; Lee Kwang-Chun ; Ryu Heung-Gyoon ;
Journal of electromagnetic engineering and science, volume 6, issue 3, 2006, Pages 182~188
Orthogonal frequency division multiplexing(OFDM) is very useful for the wireless communication system. However, OFDM is very sensitive to the radio frequency impairments. One of the most important major impairments is the IQ imbalance between in-phase(l) and quadrature(Q) branches in the up and down-conversion. IQ imbalance can be divided into phase and amplitude imbalances. These imbalances make constellation of signal to expand and rotate. The performance of system is severely degraded. In this paper, a closed-form for the bit error probability of the OFDM signal in IQ imbalance environment is derived in terms of the function of phase and amplitude imbalance parameters. So, it will be convenient and useful to evaluate the performance of OFDM communication system with IQ imbalance. It is confirmed that computer simulation results closely match with the results of the analytical derivation. When phase imbalance
, amplitude imbalance
; 0.3; 0.4; 0.5, BER at
is severely degraded by 1.8 dB, 3.12 dB, 4.72, and 8.44 dB, respectively.
The Analysis of Protection Ratio and Its Effect of Interference-to-Noise Ratio for Digital Microwave System with Diversity
Suh Kyoung-Whoan ; Jang Won-Gyu ;
Journal of electromagnetic engineering and science, volume 6, issue 3, 2006, Pages 189~195
In this paper, the derivation of the protection ratio for the digital microwave system with diversity is newly suggested for a basic guidance of initial planning for frequency coordination, and computational results are presented for an actual radio frequency band. The net filter discrimination has been also examined to see the effect of the adjacent channel protection ratio caused by adjacent channel interference. In addition, the protection ratios for the space or frequency diversity system are analyzed in terms of diversity improvement factors to find out an equivalent allowable noise-to-interference ratio (N/I) from degraded fade margin. According to results for 6.2 GHz system, with the space diversity of 25 m distance between antennas or the frequency diversity of
, under 64-QAM and 60 km at BER
, the protection ratio can be greatly reduced in comparison to the non-diversity system. So, assuming that only the same protection ratio as the non-diversity system is kept, it is shown that the system with diversity may get more interference level of N/I allowing from 9.0 to - 5.9 dB or from 6.0 to - 4.3 dB for the space or frequency diversity. In consequence, it is concluded that the diversity system is more robust or tolerable for interferences or fades, which may play an important role in overcoming N/I to some extent.