• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12A
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• pp.2000-2011
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• 2001

In this Paper, we convert conventional low speed(1x, 6x) DVD systems designed by analog PLL(Phase Locked Loop) into digital PLL to operate at high speed systems flexibly, and present optimal DPLL model in high speed(20x) DVD systems. Especially, we focused on the design of DPLL that can overcome channel effects such as bulk delay, sampling clock frequency offset and asymmetry phenomenon in high speed DVD systems. First, the modified Early-Late timing error detector as digital timing recovery scheme is proposed. And the four-sampled compensation algorithm using zero crossing point as asymmetry compensator is designed to achieve high speed operation and strong reliability. We show that the proposed timing recovery algorithm provides enhanced performances in jitter valiance and SNR margin by 4 times and 3dB respectively. Also, the new four-sampled zero crossing asymmetry compensation algorithm provides 34% improvement of jitter performance, 50% reduction of compensation time and 2.0dB gain of SNR compared with other algorithms. Finally, the proposed systems combined with asymmetry compensator and DPLL are shown to provide improved performance of about 0.4dB, 2dB over the existing schemes by BER evaluation.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.9
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• pp.67-74
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• 2016

This paper presents a novel multiple orthogonal subcarrier modulation based UHF band RFID communication system. In tag-to-reader communication, the demonstration system can deliver 1.6 Mbps through four subcarriers. To improve data rate while suppressing increase in circuit complexity, tag employs square-waves as the subcarriers and uses individual load modulators for each subcarrier. By using multiple orthogonal subcarrier based modulation, proposed communication system can be operated under existing UHF band RFID regulation. In reader, an OFDM demodulator is used. Since the tag backscatters the reader's CW carrier, carrier frequency offset compensation is not necessary in reader demodulator. Experimental results show that the demonstration system achieves a bit error rate of 10-5 at an Eb/N0 of 10.8 dB.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1817-1823
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• 2011

OFDM Modulation is used for multimedia transmission At Urban Train. Recently the application field about data transmission is expanding the image as well. The case which the number of OFDM carrier is big is advantageous because multipass fading is big 18GHz wireless frequency. Existing WLAN which an ethernet transmission is possible is not suitable to a great distance transmission because number of carrier is 64. In this paper, we developed OFDM modem suitable to transmit broadband data at high speed train. A doppler compensation block added to offset the doppler effect. Therefore, the effectiveness is expected to be very big in field of urban train.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.7 s.110
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• pp.638-647
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• 2006

Recently, the DFT-Spread OFDM has been studied for the PAPR reduction. However, the DFT-Spread OFDM produces more ICI and SCI problems than OFDM because phase offset mismatch of the DFT spreading code results from the random phase noise in the oscillator. In this paper, at first, phase noise influence on the DFT-Spread OFDM system is theoretically analyzed in terms of the BER performance. Then, the conventional ICI self-cancellation methods are discussed and two kinds of ICI self-cancellation methods are newly proposed. Lastly, a new DFT-Spread OFDM system which selectively adopts the ICI self-cancellation technique is proposed to resolve the interference problem and PAPR reduction simultaneously. Proposednew DFT-Spread OFDM system can minimize performance degradation caused by phase noise, and still maintain the low PAPR property. Among the studied methods, DFT-Spread OFDM with data-conjugate method or newly proposed symmetric data-conjugate method show the significant performance improvements, compared with the DFT-Spread OFDM without ICI self-cancellation schemes. The data-conjugate method is slightly better than symmetric data-conjugate method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.11 s.114
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• pp.1040-1049
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• 2006

A design method for minimizing transmission loss of a broadband right-angle transition from a coaxial cable to a microstrip line is presented. The right-angle transition has been widely used where printed circuit applications need to be fed from behind the ground plane using coaxial line. To obtain the minimized transmission loss over the whole operating frequency range of the transition, design parameters such as ground aperture and probe diameters, ground aperture offset, and stub length are optimized using a commercial electromagnetic simulation software. Results are presented for the optimum right-angle transition from an SMA connector to a microstrip line on common reinforced 0.787 mm thick PTFE substrates. Measurements of a fabricated transition show that reflection coefficient is less than -22 dB and insertion loss is less than 0.45 dB over $0.05{\sim}20GHz$.