• Journal of information and communication convergence engineering
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• 제7권4호
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• pp.475-479
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• 2009

In ad hoc network, the scarce energy management of the mobile devices has become a critical issue in order to extend the network lifetime. Current research activity for the Minimum Energy Multicast (MEM) problem has been focused on devising efficient centralized greedy algorithms for static ad hoc networks. In this paper, we consider mobile ad hoc networks(MANETs) that could provide the reliable monitoring and control of a variety of environments for remote place. Mobility of MANET would require the topology change frequently compared with a static network. To improve the routing protocol in MANET, energy efficient routing protocol would be required as well as considering the mobility would be needed. In this paper, we propose a new method, the CACH(Context-aware Clustering Hierarchy) algorithm, a hybrid and clustering-based protocol that could analyze the link cost from a source node to a destination node. The proposed analysis could help in defining the optimum depth of hierarchy architecture CACH utilize. The proposed CACH could use localized condition to enable adaptation and robustness for dynamic network topology protocol and this provide that our hierarchy to be resilient. As a result, our simulation results would show that CACH could find energy efficient depth of hierarchy of a cluster.

• 한국통신학회논문지
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• 제22권10호
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• pp.2205-2218
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• 1997

본 논문에서는 이동 중에 휴대용 컴퓨터와 무선 모뎀을 이용하여 원격지 컴퓨터와 정보를 교환하는 기능을 갖는 미국의 Dataradio 사에서 제안한 클라이언트/서버 구조의 무선 통신 프로토콜인 CARMA-M(Collision Avoidance Radio Multiple Access-Mobile)과 DMP(Dataradio Multiplex Protocol)를 구현하였다. 제안된 각 프로토콜의 설명, 분석과 함께 DMP, CARMA-M 그리고 이들의 접속을 위한 LLC의 구현 방법을 자세히 설명하였다. 에러 감지와 정보의 복원 기능을 갖는 FEC 기법을 첨가하였으며, 구현한 프로토콜을 검증하기 위해 사용한, 무선 환경을 유선망 형태로 모의 실험한 방법을 보였다.

• Journal of Communications and Networks
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• 제3권4호
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• pp.365-373
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• 2001

We propose a new channel reservation protocol which can reduce message delay by using a counter for detection of d source conflict in a WDM single-hop network with non-equivalent propagation delay. A source convict occurs when a source node has the right to transmit more than or equal to two messages simultaneously, which are transmitted using different wavelengths. In such a case, the source node has to newly obtain the right to transmit the message. In the proposed protocol, by using a source conflict counter a source node can detect a source conflict before a wave-length assignment is performed. Therefore, the source node can start a procedure to newly obtain the right to transmit the message which cannot be transmitted due to a source conflict. We analyse the throughput performance by taking the effect of a source conflict into account, and show that the approximate analysis and the computer simulated results are close. Also, from computer simulated results, we show that our proposed protocol can reduce mean message delay dramatically without degrading throughput performance as the offered load becomes large.

• 한국통신학회논문지
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• 제32권5B호
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• pp.247-256
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• 2007

본 논문에서는 무선 센서 네트워크를 위한 위치 정보의 시간차를 이용한 라우팅 프로토콜(Geo-Back)을 제안한다. Geo-Back은 기존의 위치 기반 라우팅 알고리즘과 달리 주기적인 이웃 노드들의 위치 정보 혹은 하나의 홉 내에 있는 이웃 노드들 수의 정보를 이용하지 않고, 오직 소스와 목적지 노드의 위치 정보만을 이용하며, 최적의 back-off 시간 메커니즘을 사용하여 패킷 전송을 결정한다. 빈번한 토폴로지 변화 환경 하에서, 제안하는 Geo-Back 프로토콜은 업데이트를 위한 브로드캐스트 알고리즘을 사용하지 알고 빠르게 목적지까지 전송하기 위한 최적의 다음 홉을 찾을 수 있으며, 분석 결과 밀집 환경의 무선 센서 네트워크에서 확장성과 향상된 성능을 확인 하였다.

• 한국정보통신학회논문지
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• 제9권5호
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• pp.934-942
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• 2005

MANET 라우팅 프로토콜들은 각각의 특정한 상황에서 장, 단점을 가지고 있다. 모든 상황에서 가장 적합한 프로토콜은 명확하지 않고, 노드들의 트래픽과 이동 특성에 따라 적합한 라우팅 프로토콜을 선택해야 한다. 본 논문에서의 주된 내용은 대한석탄공사 작업현장에 MANET을 구축할 때 적합한 라우팅 프로토콜을 선정하는 것이다. 이를 위해 노드들의 이동 특성을 반영한 채탄, 보갱과 같은 작업 시나리오를 작성하였고, 채탄과 보갱의 토폴로지를 구성하였으며, 이에 따른 MANET 라우팅 프로토콜들의 성능을 분석하였다. 본 논문의 성능 분석 결과는 대한석탄공사의 다른 광업소는 물론 지하 터널 환경에서 MANET 라우팅 프로토콜을 선택할 때 기준으로 적용될 수 있을 것이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권12호
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• pp.3018-3036
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• 2013

In this paper, we investigate power allocation scheme and outage performance for a physical-layer network coding (PNC) relay based secondary user (SU) communication in cognitive multi-antenna relay networks (CMRNs), in which two secondary transceivers exchange their information via a multi-antenna relay using PNC protocol. We propose an optimal energy-efficient power allocation (OE-PA) scheme to minimize total energy consumption per bit under the sum rate constraint and interference power threshold (IPT) constraints. A closed-form solution for optimal allocation of transmit power among the SU nodes, as well as the outage probability of the cognitive relay system, are then derived analytically and confirmed by numerical results. Numerical simulations demonstrate the PNC protocol has superiority in energy efficiency performance over conventional direct transmission protocol and Four-Time-Slot (4TS) Decode-and-Forward (DF) relay protocol, and the proposed system has the optimal outage performance when the relay is located at the center of two secondary transceivers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2405-2423
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• 2012

In a traditional Single Sign-On (SSO) scheme, the user and the Service Providers (SPs) have given their trust to the Identity Provider (IdP) or Authentication Service Provider (ASP) for the authentication and correct assertion. However, we still need a better solution for the local/native true SSO to gain user confidence, whereby the trusted entity must play the role of the ASP between distinct SPs. This technical gap has been filled by Trusted Computing (TC), where the remote attestation approach introduced by the Trusted Computing Group (TCG) is to attest whether the remote platform integrity is indeed trusted or not. In this paper, we demonstrate a Trustworthy Mutual Attestation (TMutualA) protocol as a proof of concept implementation for a local true SSO using the Integrity Measurement Architecture (IMA) with the Trusted Platform Module (TPM). In our proposed protocol, firstly, the user and SP platform integrity are checked (i.e., hardware and software integrity state verification) before allowing access to a protected resource sited at the SP and releasing a user authentication token to the SP. We evaluated the performance of the proposed TMutualA protocol, in particular, the client and server attestation time and the round trip of the mutual attestation time.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권6호
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• pp.1586-1605
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• 2012

With the prevalence of multimedia applications and the potential commercial usage of Mobile Ad hoc Networks (MANETs) in group communications, Quality of Service (QoS) support became a key requirement. Recently, some researchers studied QoS multicast issues in MANETs. Most of the existing QoS multicast routing protocols are designed with flat topology and small networks in mind. In this paper, we investigate the scalability problem of these routing protocols. In particular, a Position-Based QoS Multicast Routing Protocol (PBQMRP) has been developed. PBQMRP builds a source multicast tree guided by the geographic information of the mobile nodes, which helps in achieving more efficient multicast delivery. This protocol depends on the location information of the multicast members which is obtained using a location service algorithm. A virtual backbone structure has been proposed to perform this location service with minimum overhead and this structure is utilized to provide efficient packet transmissions in a dynamic mobile Ad hoc network environment. The performance of PBQMRP is evaluated by performing both quantitative analysis and extensive simulations. The results show that the used virtual clustering is very useful in improving scalability and outperforms other clustering schemes. Compared to On-Demand Multicast Routing Protocol (ODMRP), PBQMRP achieves competing packet delivery ratio and significantly lower control overhead.

• 인터넷정보학회논문지
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• 제9권2호
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• pp.1-13
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• 2008

최근 이동사무환경에 대한 관심이 증대되고 있다. 이를 위한 '유비쿼터스 이동사무환경 시스템'의 메신저 시스템은 기존 메신저 프로토콜에서 지원하지 않았던 파일 요청, 사무환경 전송/ 요청 / 브로드캐스팅 등 이동 사무환경 메신저 시스템을 위한 여러 가지 새로운 개념들이 필요하다. 본 논문은 이러한 이동사무환경 메신저에 맞는 새로운 프로토콜을 설계하였으며, 기존의 프로토콜과의 차이점을 분석하였다. 또한 MOE-MP에 최적화된 서버를 구현하고 이에 대한 효율성 분석을 수행하였다. 새롭게 설계한 MOE-MP는 XMPP의 기본적인 프로토콜을 사용하였고, 이동사무환경에 맞도록 확장하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권6호
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• pp.1869-1880
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• 2014

Wireless communication is one of most active areas in modern communication researches, QoS (Quality of Service) assurance is very important for wireless communication systems design, especially for applications such as streaming video etc., which requires strict QoS assurance. The modern wireless networks multi-layer protocol stack structure results in QoS metrics layered and acting in cascade and QoS metrics vertical mapping between protocol layers. Based on virtual buffer between protocol layers and queuing technology, a unified layered QoS mapping framework is proposed in this paper, in which we first propose virtual queue concept, give a novelty united neighboring protocol layers QoS metric mapping framework, and analysis method based on dicerete-time Markov chain, and numerical results show that our proposed framework represents a significant improvement over previous model.