• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.146-147
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• 2010

본 논문은 차세대 양방향 이동통신의 상향링크 전송용량 증대를 위한 다중 단말 기회 중계(opportunistic relaying) 기법을 제안한다. 제안된 기법은 단일 안테나(single antenna) 기지국과 다수의 단일 안테나 단말이 있는 협력 네트워크(cooperative network)에서 시간블록 단위로 라운드 로빈(Round-Robin)과 동일한 공정성(fairness)을 보장하면서 높은 불능확률 성능 이득을 제공한다. 컴퓨터 모의 실험결과를 통해 제안된 기법의 성능 이득 크기를 보이며, 기존의 중계 기법보다 높은 다이버시티 차수를 가짐을 확인한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.121-122
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• 2011

본 논문에서는 무선 협력 네트워크(wireless cooperative network)의 전송 신뢰성과 공정성 향상을 위한 비례공정 중계(proportional-fair relaying) 기법을 제안한다. 다중 단말과 단일 기지국이 있는 다원 접속(multiple access) 환경에서 저속 페이딩(slow fading)에 의한 성능 열화를 저감하면서 단말간 자원 사용 공정성 보장하기 위해 비례공정 전송 기법과 중계 기법 결합한다. 이를 통해 기존 기회적(opportunistic) 전송 기법의 비대칭 채널(asymmetric channel)에서의 자원 사용 불공정성을 해결하면서 깊은 페이딩(deep fading)에 의한 데이터 무선 전송 손실을 최소화 한다. 컴퓨터 모의실험 결과를 통해 제안된 기법이 공정성 제한(fairness constraint)이 있는 다원 접속 환경에서 불능 확률(outage probability) 성능을 제고함을 보인다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.894-896
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• 2010

In mobile wireless sensor network, Whole nodes can move. In mobile wireless sensor network based on clustering, there can be frequent re-configuration of cluster according to frequent changes of location. Frequent reconfiguration of the cluster cause a lot of power consumption and data loss. To solve this problem, we suggest relay method for sending reliable data and decreases a number of re-configuration of cluster using relay node.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2813-2819
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• 2015

In this paper, we investigate the physical layer network coding (PNC) technique in a two-way relay channel (TWRC) where two source nodes send and receive data with each other via a relay node. In particular, we consider the communication scenario where packet length from the two sources is different from each other. We analyze the bit error rate (BER) of the received packet at the relay node according to degree of overlapping between two packets. The BER of the short packet remains unchanged regardless of the degree of overlapping since the entire packet is overlapped with the longer packet, while the BER of the longer packet becomes improved as the degree of overlapping decreases. Thus, we need a novel transmission scheme to enhance BER performance of the PNC technique in TWRC environments since the overall BER performance of the PNC technique at the relay node depends on the worse BER between two ovelapping packets' BERs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10B
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• pp.994-1003
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• 2009

For Automatic Meter Reading System, good topology of check machines, concentrators, and repeaters in client field is important. Steiner Minimum Tree is a minimum cost tree connecting all given nodes with introducing Steiner points. In this paper, an efficient mechanism allocating and connecting check machines, concentrators and repeaters which are essential elements in automatic meter reading system is proposed, which conducts repeated applications of building approximate Minimum Steiner Trees. In the mechanism, input nodes and Steiner points might correspond to check machine, concentrators or repeaters and edges might do to the connections between them. Therefore, through suitable conversions and processes of them, an efficient network for automatic meter reading system with both wired and wireless communication techniques could be constructed. In our experiment, for 1000 input nodes and 200 max connections per node, the proposed mechanism shortened the length of produced network by 19.1% comparing with the length of Minimum Spanning Tree built by Prim's algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7A
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• pp.660-668
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• 2010

In energy resource constrained networks, the network lifetime can be enhanced by optimally allocating energy resource among users based on the available channel state information and the residual energy information at each node. In this paper, we propose the relay selection scheme and power allocation scheme to maximize the network lifetime in wireless relay networks with capacity constraint. The computer simulation results show that the proposed scheme increase the network lifetime in comparison to the conventional schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3C
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• pp.170-174
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• 2011

We introduce the network coding which cooperative communication for two-way relay channel. We propose a new network coding scheme using orthogonality for cooperative communication system. The proposed network coding scheme via orthogonal mapping shows better BER performance because proposed scheme weakens error propagation which is disadvantage of DF scheme. And proposed scheme maintains same throughput compared to conventional scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.795-802
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• 2007

In the future combat fields, US department of defense (DoD) pursuits the enhancement of the synergy effects of the force through the networking. In specially, the US army force has been emphasized the information superiority for the knowledge superiority and decision superiority of the collaboration force in the Joint Vision 2020, when the operations is performed in the battle fields. In this case study, we are reviewed about the concept of network centric operation and operation case in the centering around the US and analyzed the quantitative distance and effect, performance of communication relay about the distance of mission operation.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.805-807
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• 2001

본 논문은 P2P 네트워크 구조에 기반한 보안 모텔 구청에 관한 것을 논하고 있다. 현재 많이 사용되고 있는 P2P 프로토콜중에는 중계서버가 있어 각각의 peer가 데이터를 공유하고, 검색할 수 있게 하는 방법과 중계서버가 존재하지 않고 peer간의 통신만으로 구성되어지는 방식이 있다. 본 논문에서는 두 가지 방식의 장점을 이용해서 서버를 통하여 다른 peer의 정보를 얻어 올 수도 있으나 그렇지 못한 경우에도 캐쉬된 기존 정보에서의 자체 검색과 다른 peer와의 통신을 통해서 P2P 동작이 가능하도록 네트워크을 구성하였다. 이러한 P2P 네트워크 구조에서 취약할 수 있는 보안환경을 SSL(Secure Socket Layer)을 이용하며 웹 (web)을 통해 서버와 통신하는 단계와 peer 간에 정보 교환을 위한 통신에 적용하였으며, 그룹키(group key)를 이용하여 보안 멀티캐스트 환경을 구현하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.93-97
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• 2015

In this Paper, we proposed optimization of system performance, optimal splitting factor applied to power splitting protocol with relay in the cooperative communication undergo co-channel interference. We can possible to optimize and maximize the channel capacity of the receiver through optimal factor of splitting protocol. So, we can solve inability in system, and to increase the efficiency of the network. Finally, performance of the proposed protocol is analyzed in terms of outage probability, capacity of system.