• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11C
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• pp.1076-1084
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• 2009

We propose an ATI (Adaptive Tone Injection) scheme based on clipping noise for PAPR (Peak-to-Average Power Ratio) reduction of OFDM (Orthogonal Frequency Division Multiplexing) signals. The proposed scheme is composed of three steps: clipping, tone selection, and TI procedures. In the first step, the peak samples in the IFFT (Inverse Fast Fourier Transform) outputs are scaled down by clipping. In the second step, the sub-carrier position where the power of the clipping noise is the maximum, is selected. Finally, the generic TI procedure is performed. Simulation results show that the proposed scheme does not require all the possible combinations of the original TI procedures, while maintaining the PAPR reduction performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.10 s.113
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• pp.976-984
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• 2006

OFDM system is very useful for the high speed communication system. However, OFDM system has a serious problem of high PAPR that results from the so many subcarriers in the same phase. This OFDM signal is distorted through the nonlinear HPA(High Power Amplifier). Tone reservation method is to insert tone signal in several types to reduce the PAPR after iterating this process by changing the tone signal. Also discrete cosine transform(DCT) can reduces the PAPR as multiplying the cosine value to change the angle and mix up with the data. In the paper, the combination of the TR method and DCT method is newly proposed for more effective reduction of the PAPR. Simulation results show that the proposed method outperforms the conventional simple TR method and DCT method with respect to the PAPR reduction and BER performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5A
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• pp.363-371
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• 2009

OFDM(orthogonal frequency division multiplexing) is very effective forhigh data rate transmission system. However, communication performance becomes worse because of nonlinear distortion resulting from the PAPR. In this paper, we like to propose a tone-controlled CI/OFDM system including the TMD (inter-modulation distortion) reduction method in order to improve the BER performance. In this tone-controlled CI/OFDM system, control tone is additionally inserted in each data symbol of CI/OFDM system to make the CI/OFDM lower the PAPR and robust to nonlinear distortion. So, tone-controlled CI/OFDM using the IMD reduction method shows better BER (bit error rate) performance than methods based on PAPR reduction.

• Journal of IKEEE
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• v.24 no.1
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• pp.72-80
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• 2020

This paper describes the design and fabrication of a BUC(Block Up-converter) which is a component of a FST (Flyaway Satellite Terminal), one of the ET(Earth Terminal) of the military satellite. BUC is physically composed of an up-converter module, a high power amplifier module, a receive band suppression filter, a housing, and a cable assembly. It was designed using simulator AWR to satisfy the electrical characteristics of BUC's such as maximum output power, gain, unwanted signal, and intermodulation. The maximum output power and gain characteristics were measured at 43.4dBm and 51.8dB, respectively. The unwanted wave and intermodulation characteristics were -73.5dBc and -31.9dBc, respectively. Of the electrical requirements of Table 1, not only the above four but also all of the items were confirmed to be satisfied.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.1
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• pp.21-28
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• 2009

DFT-spread OFDM(Discrete Fourier Transform-Spread Orthogonal Frequency Division Multiplexing) is very effective for solving the PAPR(Peak-to-Average Power Ratio) problem. Therefore, the SC-FDMA(Single Carrier-Frequency Division Multiple Access) which is basically same to the DFT spread OFDM was adopted as the uplink standard of the 3GPP LTE ($3^{rd}$ Generation Partnership Project Long Term Evolution). Unlike the ordinary OFDM system, the SC-FDMA using DFT spreading method is vulnerable to the ICI(Inter-Carrier Interference) problem caused by the phase noise and IQ(In-phase/Quadrature) imbalance and effected FDE(Frequency Domain Equalizer). In this paper, the ICI effects from the phase noise and IQ imbalance which can be problems in uplink transmission are analyzed according the back-off level of HPA. Next, we propose the equalizer algorithm to remove the ICI effects. This proposed equalizer based on the FDE can be considered as up-graded and improved version of PNS(Phase Noise Suppression) algorithm. This proposed equalizer effectively compensates the ICI resulting from the phase noise and IQ imbalance. Finally, through the computer simulation, it can be shown that about SNR=14 dB is required for the $BER=10^{-4}$ after ICI compensation when the back-off is 4.5 dB, $\varepsilon=0.005$, $\phi=5^{\circ}$, and $pn=0.06\;rad^2$.