• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1894-1899
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• 1994

In this paper, a new identification method is proposed for unknown digitally modulated input signals. The proposed identification method is implemented using a self-organized neural network which is based on the characteristic features of the symbol magnitude; the number of symbol magnitude levels, amplitude probability density and adjacent symbol magnitude ratio. The proposed method was performed for 5 QAM signals. The simulation results show that the self-organized neural network can accurately recognize all kinds of patterns even at SNR 8dB. The proposed method can be applied to the intelligent communication system on ISDN and multi-point polling networks.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.401-406
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• 2013

In this paper, the optimum transmission method is proposed to save the energy and to increase the throughput of the adaptive modulation mobile radio system with frame length control. Traditionally, adaptive modulation has been used to improve the throughput using the power margin of the system design. Considering the frame length vs energy saving and adaptive modulation, the optimum transmission method is proposed for hub and mobile station each.

• Journal of Digital Convergence
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• v.10 no.9
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• pp.369-374
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• 2012

In this paper, the effective transmission method is proposed to save the energy and to increase the throughput of the communication system using adaptive modulation. Traditionally, adaptive modulation has been used to improve the throughput using the power margin of the system design. Considering the instantaneous energy during the modulation method changing duration, the effective transmission method is proposed. By the simulation, the performance and effectiveness is validated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.11
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• pp.1933-1938
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• 2008

There are the frequency shift keying(FSK), phase shift keying(PSK) and amplitude shift keying(ASK) in the conventional digital communications method. In this parer, We proposed the algorithm for wavelet shift keying system using a binary matching filter in the digital communication. Wavelet shift keying system are used to a scaling function(low frequency) and wavelet(high frequency) coefficients. The binary data is encoded by modulator which assigned the scaling function to 1(one), and wavelet to zero(0). Wavelet shift keying of the conventional method needs to a post-processing for the decoding. In this paper, wavelet shift keying signal is reconstructed by the decoder using a binary matching filter. So, it was able to the decoding without the post-processing. It was demonstrated by the experiment that the proposed algorithm is a validity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.3
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• pp.427-432
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• 2021

In this paper, we conduct performance analysis in automatic modulation classification of unknown communication signal to identify its modulation types based on deep neural network. The modulation classification performance was verified using time domain digital sample data of the modulated signal, frequency domain data to which FFT was applied, and time and frequency domain mixed data as neural network input data. For 11 types of analog and digitally modulated signals, the modulation classification performance was verified in various SNR environments ranging from -20 to 18 dB and reason for false classification was analyzed. In addition, by checking the learning speed according to the type of input data for neural network, proposed method is effective for constructing an practical automatic modulation recognition system that require a lot of time to learn.

• The Journal of the Acoustical Society of Korea
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• v.10 no.4
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• pp.19-26
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• 1991

$GQ^2PSK$ which is a novel digital mobile communication modulation scheme has been introduced and described. $GQ^2PSK$ is a modulation scheme that bandlimits NRZ digital data with Gaussian filter and modulates it by $Q^2PSK$ scheme which uses two shaping pulses and two carriers which are pairwise quadrature. Thus transmission bit rate can be enhanced and available signal space dimensions are more efficiently utilized, with comparison to the already-existing GMSK, QPSK and OQPSK modulation methods. Via the computer simulation, bit error rate of $GQ^2PSK$ scheme which is bandlimited by gaussian filter to be suitable for digital mobil communication, is lower than that of $Q^2PSK$ by 1.4[dB] in case that the signal-to-noise ration is 0[dB], but we have confirmed that $GQ^2PSK$ modulation scheme is approximately equivalent to the GMSK in the respect of power efficiency, and transmission efficiency of $GQ^2PSK$ is improved to 1.5 times than that of GMSK.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.220-227
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• 2011

With the rapid development of mobile communication technology, the technologies based on the diverse digital modulation schemes have been used for the frequency range of over 800 MHz. The only radiation immunity has been tested using only AM signal based on IEC 61000-4-3 without any consideration of the influence of electromagnetic radiation in Korea. However, it has not been tested by wideband digital modulation signals such as cdmaone(IS-95), WCDMA and PM signal. The purpose of this study was to review the standards. In addition, the input signals were analyzed and tested considering the environments in Korea. The results showed that the devices were influenced by digital modulation signal or PM signal more than by AM signal.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.203-206
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• 2008

기존의 대표적인 디지털 통신방식으로 주파수 편이 변조(FSK: frequency shift keying), 위상 편이 변조(PSK: phase shift keying), 진폭 편이 변조(ASK: amplitude shift keying) 방식들이 있다. 본 논문에서는 2진 정합필터를 이용하여 웨이브릿 편이변조 신호를 복원하는 알고리즘을 제안한다. 웨이브릿 편이 변조 시스템은 스케일링 함수(scaling function)와 웨이브릿(wavelet)을 이용한다. 스케일링 함수를 1로, 웨이브릿 함수를 0으로 할당하여 2진 데이터를 변조한다. 기존의 웨이브릿 편이 변조 시스템에서는 복원을 위해 후처리가 필요하였다. 된 논문에서는 2진정합필터를 이용하여 복원하므로, 별도의 후처리 과정 없이 복원을 가능하게 하였다. 모의실험 결과 제안한 알고리즘이 타당함을 확인하였다.

• TTA Journal
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• s.51
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• pp.94-96
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• 1997

일본의 주요 연구소들은 디지털 지상방송 시스템의 개발을 위하여 변조방식을 중점으로 기본적인 현장시험을 공동으로 시작할 예정이다. 이 현장시험은 디지털 지상 TV방송의 조기도입을 촉진하도록 1998년까지 잠정적인 방송시스템의 설정을 목표로 진행되고 있다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.165-168
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• 2006

최근 디지털 변복조 방식에서 추가적인 전송률 증가를 통하여 기존 시스템의 성능개선 및 서비스의 유연성 확보를 위해 계층변조에 대한 연구가 활발하다. 기존의 QAM(quadrature amplitude modulation)계열의 계층변조 방식은 이미 많은 연구를 통해 분석되고 응용되고 있지만 차분변조 방식을 취하고 있는 DQPSK(differential quadrature phase shift keying) 방식에 대한 계층변조 기법은 아직까지 선행연구가 활발히 진행되지 않았다. 본 논문에서는 DQPSK방식에 가능한 계층변조기법을 성상에 따라 분석하고 DQPSK방식에 가장 적합한 계층변조기법을 도출한다.