• 한국통신학회논문지
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• 제35권9A호
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• pp.896-905
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• 2010

In this paper, we present a new sensing method based on phase entropy. Entropy is a measurement which quantifies the information content contained in a signal. For the PSK modulation, the information is encoded in the phase of the transmitted signal. By focusing on phase, more information is collected during sensing, which suggests a superior performance. The sensing based on Phase entropy is not limited to PSK signal. We generalize it to PAM signal as well. It is more advantageous to detect the phase. The simulation results have confirmed the excellent performance of this novel sensing algorithm.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2000년도 추계학술대회 학술발표 논문집
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• pp.231-234
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• 2000

In this paper, we formed a transmitter and receiver by using three identical Chuas circuits and then formed wire and wireless transmission line from the channel which was between those three circuits. We proposed a secure communication method in which the desired information signal was synthesized with the chaos signal created in a Chuas circuit and sent to the transmitter through channel. Then the signal was demodulated receiver of Chuas circuit. The method we used to accomplish the secure communication was synthesizing the desired information with the chaos circuit by parallel connection in a wireless transmission line. After transmitting the synthesized signal to the wire and wireless transmission line, we confirmed the actuality of the secure communication by separating the information signal and the chaos signal in the receiver.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 심포지엄 논문집 정보 및 제어부문
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• pp.65-67
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• 2004

Change of state of Channel between two wireless terminals which is caused by noise and multiple environmental conditions for happens frequently from the Wireles Network. So, When it is like that planning a wireless network protocol or performance analysis, it follows to change of state of time-varying channel and packet the analysis against a transmission efficiency is necessary. In this paper, analyzes transmission time of a packet and a packet in a time-varying and packet based Wireless Network. To reflecte the feature of the time-varying channel, we use a Signal Flow Graph model. From the model the mean of transmission time and the mean of queue length of the packet are analyzed in terms of the packet distribution function, the packet transmission service time, and the PER of the time-varying channel.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 추계종합학술대회
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• pp.263-266
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• 2000

In this paper, we formed a transmitter and receiver by using two identical Chua's circuits and then formed wireless transmission line from the channel which was between those two circuits. We proposed a secure communication method in which the desired information signal was synthesized with the chaos signal created in a Chua's circuit and sent to the transmitter through channel. Then the signal was demodulated receiver of Chua's circuit. The method we used to accomplish the sun communication was synthesizing the desired information with the chaos circuit by parallel connection in a wireless transmission line. After transmitting the synthesized signal to the wireless transmission line, we confirmed the actuality of the secure communication by separating the information signal and the chaos signal in the receiver. In order to confirm the security, we compared the wiretapped signal and the recovery signal under the assumption that the wiretapping had taken place. In order to separate the two signals, we transformed the information signal to a current source in the transmitter and detected the current in the receiver.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 춘계종합학술대회
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• pp.238-241
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• 2000

In this paper, we formed a transmitter and receiver by using two identical Chua's circuits and then formed wireless transmission line from the channel which was between those two circuits. We proposed a secure communication method in which the desired information signal was synthesized with the chaos signal created in a Chua's circuit and sent to the transmitter through channel. Then the signal was demodulated receiver of Chua's circuit. The Method we used to accomplish the secure communication was synthesizing the desired information with the chaos circuit by parallel connection in a wireless transmission line. After transmitting the synthesized signal to the wireless transmission line, we confirmed the actuality of the secure communication by separating the information signal and the chads signal in the receiver. In order to confirm the security, we compared the wiretapped signal and the recovery signal under the assumption that the wiretapping had taken place. In order to separate the two signals, we transformed the information signal to a current source in the transmitter and detected the current in the receiver.

• 대한전자공학회논문지TC
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• 제42권2호
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• pp.23-38
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• 2005

무선 네트워크에서는 여러 가지의 환경적 요인으로 인해 발생하는 페이딩 현상 및 노이즈로 인하여 무선 단말기 간의 채널의 상태가 자주 변화한다. 따라서 시변 채널 특성을 지니는 무선 네트워크에서 신뢰성 있는 데이터 전송을 위해서는 시변 채널 특성을 파악하는 것이 중요하다. 본 논문에서는 무선 네트워크 시변(Time-varying) 채널 상에서 패킷 전송 시간 및 대기큐에 대해 분석한다. 무선 네트워크 시변 채널 상태를 반영하기 위해 채널의 상태를 2-상태, 3-상태 각각의 경우로 구분하고 SFG(Signal Flow Graph) 모델을 이용하여 채널 상태를 해석한다. 각각의 상태에 대한 SFG 모델로부터 하나의 패킷에 대해 평균 전송시간과 분산을 구하고 이에 대한 확률 분포를 가우시안(Gaussian) 분포로 생각한다. 패킷의 도착분포가 프아송(Poisson) 프로세스를 따르는 전송 시스템을 M/G/1으로 모델링하고 에러 정정 기법으로 SW ARQ 기법을 적용하여 패킷의 PER의 변화 및 패킷 도착 비율의 변화에 따른 평균 패킷 전송시간과 평균 대기큐의 길이에 대해 해석하고 시뮬레이션을 통하여 검증한다.

• 한국인터넷방송통신학회논문지
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• 제10권5호
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• pp.89-96
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• 2010

본 논문은 방송현장에서 TV중계차와 EFP카메라 또는 ENG카메라간의 카메라 케이블 연결이 방송프로그램 제작시 여러가지 장애물과 거리에 한계가 있어 자유로운 카메라 촬영활동에 불편을 주고 있는바, DVB-T방송에서 사용하는 무선영상 전송장치와 수신장비를 제작하여 본 연구에 응용하는 사례로, 야외는 물론 실내에서도 카메라 촬영활동이 자유스러운 "Wireless 카메라 영상전송 시스템"의 개발을 목표로 하였다. 본 연구는 연구접근이 용이한 아날로그 콤포지트 영상신호 출력을 갖는 카메라와 이 영상신호를 압축하는 MPEG-2시스템, COFDM 전송방식을 이용하는 영상전송시스템으로 제작실험하게 되었으며, 그 결과 영상 및 전송장치에 대하여 양호한 QoS값을 얻게 되었으며, 본 실험을 통해 TV방송제작 현장의 활용은 물론, 무선 CCTV 장치산업의 적용 할 수 있는 가능성을 갖게 되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.424-442
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• 2014

Most recent research on iterative solutions for interference alignment (IA) presents solutions assuming channel reciprocity based on the suppression of interference from undesired sources by using an appropriate decoding matrix also known as a receiver combining matrix for multiple input multiple output (MIMO) interference channel networks and reciprocal networks. In this paper, we present an alternative solution for IA by designing precoding and decoding matrices based on the concept of signal leakage (the measure of signal power that leaks to unintended users) on each transmit side. We propose an iterative algorithm for an IA solution based on maximization of the signal-to-leakage-and-noise ratio (SLNR) of the transmitted signal from each transmitter. In order to make an algorithm removing the requirement of channel reciprocity, we deploy maximization of the signal-to-interference-and-noise ratio (SINR) in the design of the decoding matrices. We show through simulation that minimizing the leakage in each transmission can help achieve enhanced performance in terms of aggregate sum capacity in the system.

• 디지털콘텐츠학회 논문지
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• 제14권3호
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• pp.349-356
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• 2013

최근 스마트폰과 같은 무선통신기기의 급증으로 인하여 IEEE 802.11 Wi-Fi 네트워크에서 인접 네트워크간의 신호간섭현상이 많이 발생하며, 이와 같은 신호간섭현상은 데이터 전송 품질에도 영향을 미친다. 현재 출시되고 있는 다수의 Wi-Fi 관련 제품들은 높은 데이터 전송률 및 넓은 전송범위를 보여주고 있지만, 반면 이 같은 특성은 인접한 무선기기와의 무선신호간섭 확률도 높게 한다. 무선신호간섭은 무선통신 특성상 피하기 어려운 현상이지만 통신기기의 신호전송범위를 작게 함으로서 최소화할 수 있다. 그러나 작은 신호전송범위는 낮은 송신강도를 의미하므로, 이는 낮은 데이터 전송률로 나타나게 된다. 이에 본 논문에서는 신호강도, 전송률, 신호간섭간의 상호 관계를 분석하고, 송신 강도와 전송률의 tradeoff로서 무선기기의 위치 및 RSSI(Received Signal Strength Indication)에 따라 송신강도를 가변적으로 조절하는 가변 커버리지 기반의 Wi-Fi 네트워크 방식을 제안하고, 이의 성능을 시뮬레이션을 통하여 구한다.

• Journal of information and communication convergence engineering
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• 제9권6호
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• pp.676-682
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• 2011

Sybil attack can disrupt proper operations of wireless sensor network by forging its sensor node to multiple identities. To protect the sensor network from such an attack, a number of countermeasure methods based on RSSI (Received Signal Strength Indicator) and LQI (Link Quality Indicator) have been proposed. However, previous works on the Sybil attack detection do not consider the fact that Sybil nodes can change their RSSI and LQI strength for their malicious purposes. In this paper, we present a Sybil attack detection method based on a transmission power range. Our proposed method initially measures range of RSSI and LQI from sensor nodes, and then set the minimum, maximum and average RSSI and LQI strength value. After initialization, monitoring nodes request that each sensor node transmits data with different transmission power strengths. If the value measured by monitoring node is out of the range in transmission power strengths, the node is considered as a malicious node.