• The Journal of Information Technology
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• v.6 no.2
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• pp.1-8
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• 2003

This paper is about power line communication(PLC) over the low power voltage grid. The main advantage with power line communication is the use of an existing infrastructure. The PLC channel can be modeled as having multi-path propagation with frequency-selective fading, typical power lines exhibit signal attenuation increasing with length and frequency. OFDM(Orthogonal Frequency Division Multiplexing) is a modulation technique where multiple low data rate carriers are combined by a transmitter to form a composite high data rate transmission. To implement the multiple carrier scheme using a bank of parallel modulators would not be very efficient in analog hardware. Each carrier in an OFDM is a sinusoid with a frequency that is an integer multiple of a base or fundamental sinusoid frequency. Therefore, each carrier is a like a Fourier series component of the composite signal. In fact, it will be shown later that an OFDM signal is created in the frequency domain, and then transformed into the time domain via the Discrete Fourier Transform(DFT).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.11
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• pp.1054-1062
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• 1991

In this paper a communication system using direct sequence spread spectrum (DS/SS) technique is constructed to transmit burst format data over power line channel with impulsive noise and narrowband interferences. Fast code synchronization is acquired by digital matched filter and data decision is accomplished by sampling pulses. In order to examine the performance of the power line communication system, but error rate and packet loss rate are measured over the simulation channel with various noise sources. When the packet composed of 1-bit preamble and 63-bit data is transmitted under very high burst impulsive noise, the bit error rate is about 10$^3$-10$^4$ and the packet loss rate is below 0.07.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1994-1995
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• 2007

본 논문에서는 가로등 제어를 위한 전력선 통신 프로토콜을 OSI 7계층을 바탕으로 설계하고, 실제 적용해 봄으로써 그 실용성을 입증한다. 그러나 전력선 채널의 상태가 좋지 않으면 멀리 있는 모뎀까지의 전송 확률이 떨어짐을 확인하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.2
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• pp.47-55
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• 2010

The power line communication channel has characteristic variation problems which are caused by load. The spread spectrum technique has been used to overcome these problems. One of that is the direct sequence spread spectrum(DS/SS) system which is not necessary to additional hardwares. The BER of DS/SS system is decreased by longer length of PN code, but data transfer rate is decreases, so data transfer rate is hard to satisfies their own specifications especially in narrowband PLC systems. Spread Spectrum system with Dual-processing Gain tries to reflect cyclic characteristics of power line noise. But that system assumes that shapes of power line channel are symmetrical with respect to the 1/4 point of main frequency(60Hz in Korea), therefore cannot achieves various shapes of real power line noise. Thus in this paper, noise adaptive DS/SS system which PN code is changed by noise levels for various channel noises is proposed and simulated. The different kinds of noises are modeled and measured for simulation, the proposed system is verified that has lower data transfer rate and lower error rate than conventional system by simulation results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.11
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• pp.79-86
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• 2005

This paper describe a method for measuring line impedance as a function of frequency for an energized powerline in normal operation. A small sinusoidal signal of a powerline communication utility frequency $30khz\~1Mhz$ band is continuously injected into the line, and a implemented impedance analyzer calculates the indoor powerline channel impedance from the measured magnitude and phase of resulting voltage and current. The impedance measurement is executed over a range of frequencies to produce a wideband impedance versus frequency characteristic. Implemented impedance analyzer can analysis powerline communication environments measuring line impedance due to load caused in indoor. And measured analysis information through the database can use to evaluate performance of modem and to decide test environment standard.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2043-2044
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• 2006

배전 계통을 대상으로 하는 통신 시스템에 전력통신(PLC : Power Line Communication)기술을 적용하고자 할 때, 고압 배전선의 통신 채널로서의 특성 분석이 근간이 되어야 한다. 일반적으로 지하 공동구의 배전 지중 케이블에는 케이블-케이블 간의 전기적, 물리적 접촉점인 접속 개소가 일정한 간격으로 존재하게 된다. 그러므로 통신 신호의 매개체가 되는 전력 케이블의 채널 특성 분석에는 케이블 접속 개소의 영향도 고려 대상이 되어야 한다. 본 논문에서는 서울시 광진구 일부의 부하를 담당하고 있는 22.9 kV 고압 배전 지중 선로를 시험 선로로 비접촉식 커플러를 통해 통신 신호를 전송하여 삽입 손실 측정 결과를 보았고 케이블 접속 개소의 영향을 주파수 영역에서 채널 특성을 통해 분석 하였다. 시험 결과 케이블 접속 개소를 통과할 때 채널 특성은 십여 dB의 신호 감쇄를 보였다.

• The Journal of Information Technology
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• v.5 no.4
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• pp.1-8
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• 2002

This thesis is about power line communication(PLC) over the low voltage grid. The main advantage with power line communication is the use of an existing infrastructure. The PLC channel can be modeled as having multi-path propagation with frequency-selective fading, typical power lines exhibit signal attenuation increasing with length and frequency. OFDM(Orthogonal Frequency Division Multiplexing) is a modulation technique where multiple low data rate carriers are combined by a transmitter to form a composite high data rate transmission. To implement the multiple carrier scheme using a bank of parallel modulators would not be very efficient in analog hardware. Each carrier in an OFDM is a sinusoid with a frequency that is an integer multiple of a base or fundamental sinusoid frequency. Therefore, each carrier is a like a Fourier series component of the composite signal. In fact, it will be shown later that an OFDM signal is created in the frequency domain, and then transformed into the time domain via the Discrete Fourier Transform(DFT).

• 전자공학회논문지 IE
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• v.44 no.4
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• pp.30-34
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• 2007

The Channel environment is poor in the power line communication because power line proposed power supply use a communication medium. In this paper, we designed gate drive circuit used coupler reducing the signal diminution for the good communication. We analyzed receiving and transmitting operation of the coupler and designed the drive circuit with the suitable impedance. As a result, we improved the environment of impedance variation due to the inter reaction of many electron products. So, to improve BER(45%) enabled us to communicate smoothly in power line communication.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.221-224
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• 2005

본 논문에서는 워터마크가 삽입된 데이터의 저작권 보호를 위하여 데이터의 복제 시 신속한 위치추적을 통한 불법 복제 방지 시스템을 제안하고 시뮬레이션 하였다. 제안된 방법은 복사기, 프린터, 스캐너 등에 부착된 워터마크 검출 장치로부터 워터마크 검출 시 원 워터마크 이미지와 추출된 워터마크이미지가 일정 비 이상의 상관관계가 있을 경우 불법 복제 상황으로 간주하고, 디지털 데이터로 변환된 워터마크 이미지와 주소 정보가 전력선을 통하여 전송된다. 수신단에서는 수신된 데이터의 발신자 정보를 통해 위치정보를 알아내어 불법 복제 작업현장의 위치를 추적한다. 전력선을 통신선로로 이용 시 전송신호는 전력선 채널 환경에서 임펄스 잡음에 많은 영향을 받기 때문에 본 논문에서는 제안한 시스템의 검증을 위해 AWGN과 임펄스 잡음을 고려하고 잡음 특성이 우수하고 신뢰성이 비교적 강한 DS-CDMA/BPSK 시스템을 통해 제안된 시스템을 시뮬레이션 하였다. 또한, 열악한 채널 환경으로부터 수신성능을 개선하기 위해 컨벌루션 부호화기법을 적용하여 성능 개선 전 후의 복원 이미지의 성능을 비교 분석 하였다.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.146-151
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• 2017

This paper proposes a transmission algorithm that optimizes transmission power and sub-channel allocation to maximize energy efficiency considering characteristics of the channel impedance of power lines in power line communication systems. Since the received power at the receiver is influenced by the characteristics of the power line channel, it is necessary to consider channel characteristics when developing a transmission strategy in a power line communication systems. In addition, the energy efficiency should be optimized while meeting the practical constraints, such as the maximum transmission power limit of the transmitter and minimum quality of service for each user. In the computer simulation, we confirm that the energy efficiency of the proposed algorithm is improved compared to baseline schemes.