• Journal of Internet Computing and Services
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• v.16 no.2
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• pp.7-17
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• 2015

To provide scalability, wireless sensor network has cluster-based architecture. Wireless sensor network can be implemented based on the IEEE 802.15.4 which is exploited in 2.4GHz ISM frequency band. Since this frequency band is used for various data communication, network status of wireless sensor networks frequently changes according to wireless environment. Thus, wireless channel selection to avoid reduction of transmission efficiency is required. This paper estimates network status using the information that a cluster-head collects in a cluster. Through objective function with throughput, RSSI level and reliability as input parameters, this paper proposes proper wireless channel selection. Simulation results show that the proposed method maintains transmission efficiency even though network status changes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.441-450
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• 2006

WiBro(Portable Internet Service) is service being capable to provide a high data rate wireless internet access with Personal Subscriber Station under the stationary or mobile environment, anytime and any where. It will fill the gap between very high data rate wireless local area networks and very high mobility cellular systems. The security is an important point of WiBro providing high data and mobile wireless services. This paper proposes user authentication mechanism of WiBro wireless networks applied EAP-AKA authentication protocol. As a result of Wireless authentication based on EAP-AKA, this mechanism is capable to be used in WiBro-WLAN-3GPP interworking scenario as well as the WiBro authentication mechanism.

• The KIPS Transactions:PartC
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• v.19C no.1
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• pp.71-82
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• 2012

In Next Generation Wireless Networks (NGWN), lots of information, such as voice and video data, will be used in All-IP networks. It is important note that seamless service for users and handoff between heterogeneous networks must be taken into account in such environments. Therefore, in this paper, we propose a SePH(Seamless Proxy based Handoff) using PMIPv6-based proxy model which is enable to improve the performance of handoff in NGWN. The SePH can efficiently support seamless and IP-based mobility by reducing the search process. The performance results show that our proposed scheme outperforms in terms of QoS (Quality of Service) such as throughput, handoff latency, packet loss, and signaling overhead comparing to the existing schemes.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.428-432
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• 2011

차량 통신 네트워크(VANET, Vehicle Ad hoc NETwork)는 ITS(Intelligent Transport System)의 발전과 함께 운전자의 안전 및 교통 정보, 긴급 메시지 등과 같은 서비스를 실시간으로 가능하게 할 수 있는 차세대 네트워크 기술이다. 이러한 차량 통신 네트워크는 현재 IEEE P1609에서 정의하고 있으며, WAVE(Wireless Access Vehicular Environment)로 알려져 있다. WAVE는 차량에 설치된 OBU(Onboard Unit)와 주변시설에 설치된 RSU(Road Side Unit)을 통하여 통신하며, 차량 간 통신을 지원하는 V2V(Vehicle to Vehicle)와 차량과 주변시설과의 통신을 지원하는 V2I(Vehicle to Infrastructure)로 나뉘어져 있다. 하지만 WAVE에서 정의하고 있는 네트워크 서비스(IEEE P1609.4)는 OBU와 RSU 간의 네트워크 서비스에 초점을 맞추고 있기 때문에 전체 네트워크의 QoS를 보장하기에는 미흡한 상태이다. 따라서 본 논문에서는 차량 통신 네트워크에서 End-to-End 간의 QoS 보장을 위한 무선 메쉬 네트워크 기반의 라우팅 알고리즘을 제안한다. 제안하는 알고리즘은 무선 메쉬 네트워크 노드의 호스트 라우터 기능을 통하여 차량 노드와 이기종 간의 네트워크 서비스를 가능하게 하며, 무선 메쉬 네트워크의 다중 채널을 이용하여 데이터의 중요도에 따른 차등 서비스를 지원한다. ns-2를 이용한 시뮬레이션 결과 제안하는 알고리즘이 QoS를 보장함으로써 차량 통신 네트워크의 성능을 향상시킬 수 있음을 입증하였다.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.31-37
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• 2006

To achieve the efficient performance within a mobile grid considering the intermittent network connectivity and non-dedicated heterogeneous mobile devices, this paper suggests the scheduling algorithm of job allocation as a viable solution. The suggested scheduling algorithm has two core functions, the prediction of response time for task processing and the identification of the optimal number of mobile devices to process the mobile grid applications. This scheduling algorithm suggests the numerical formulas to calculate the network latency considering the effects of heterogeneous non-dedicated mobile system in wireless network environments. Also we evaluate the performance of mobile grid system using the processing the distributed applications in implemented mobile grid environments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.47-58
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• 2018

The heterogeneous cellular network (HCN) is most significant as a key technology for future fifth generation (5G) wireless networks. The heterogeneous network considered consists of randomly macrocell base stations (MBSs) overlaid with femtocell base stations (BSs). The stochastic geometry has been shown to be a very powerful tool to model, analyze, and design networks with random topologies such as wireless ad hoc, sensor networks, and multi- tier cellular networks. The HCNs can be energy-efficiently designed by deploying various BSs belonging to different networks, which has drawn significant attention to one of the technologies for future 5G wireless networks. In this paper, we propose switching off/on systems enabling the BSs in the cellular networks to efficiently consume the power by introducing active/sleep modes, which is able to reduce the interference and power consumption in the MBSs and FBSs on an individual basis as well as improve the energy efficiency of the cellular networks. We formulate the minimization of the power onsumption for the MBSs and FBSs as well as an optimization problem to maximize the energy efficiency subject to throughput outage constraints, which can be solved the Karush Kuhn Tucker (KKT) conditions according to the femto tier BS density. We also formulate and compare the coverage probability and the energy efficiency in HCNs scenarios with and without coordinated multi-point (CoMP) to avoid coverage holes.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.3
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• pp.156-161
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• 2012

Random access protocol takes advantage of constructing a decentralized wireless network due to its intrinsic spectrum sensing capability. Such technical feature goes well with cognitive radio networks consisting of heterogeneous wireless systems, in which a centralized control between heterogeneous wireless systems is hard to be implemented. Motivated by the decentralized feature of the random access, we adopt the random access protocol in cognitive radio networks, and evaluate the performance of a CSMA-based cognitive radio network.

• Journal of Korea Multimedia Society
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• v.11 no.8
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• pp.1121-1128
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• 2008

Ad-Hoc network is consisted with the device of wireless communication. Therefore, the organization of network is dynamic and the changing communication channel is essential. According this, the study of secure routing route and certification technique has to be needed. In we research, we suggest not only the secure routing scheme in Ad-Hoc circumstance but also the method that user can be serviced the type of network which is connected Ad-Hoc network and wireless lam. In case of the routing form of Ad-Hoc Network, although in preexist study, when the device of organization withdraws, routing is needed, in we research, we suggest the detour route that is used hop frequency. We can offer the service of ubiquitous that the certification of secure user and the creation of routing route in Ad-Hoc network.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.1
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• pp.1-10
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• 2012

Mobility and quality of service (QoS) are becoming the more important issues in wireless communications. The traditional Internet service is expanding into new access media and applications. Since wireless communication services are accompanied by frequent handovers at remote sites, scalable and fast handover has become a prerequisite for ubiquitous communication. In this paper, the differentiated service (Diffserv) model is deployed in heterogeneous proxy mobile IPv6 (PMIPv6) networks to satisfy the QoS guaranteed service and fast handover requirements. The operational procedures for QoS guaranteed global roaming are presented. In addition, QoS management and handover cost evaluation schemes based on a mobile host's movement scope are proposed. This paper analyzes the reduction in handover delay in a network-based localized mobility management framework. We propose and analyze a PMIPv6 optimized with a global mobile access gateway (G-MAG), which is a network-based entity, to further improve the handover performance in terms of handover delay while maintaining minimal signaling overhead in the air interface among converged heterogeneous wireless networks. The handover signaling procedures with host-based MIPv6 are compared with network-based proxy MIPv6 (PMIPv6) and fast PMIPv6 assisted by G-MAG to show how much handover delay reduction can be achieved. Analytical results show that the handover delay is significantly reduced.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.2
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• pp.313-324
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• 2015

In this paper, in order to support the construction of a smart home environment of low power consumption, we propose a heterogeneous interface determination engine and architecture. Technology of "smart home" is in the spotlight according to the development of IT technology nowadays. Smart homes are configured with multiple sub-networks, and each sub-network is formed by the smart devices using various communication interfaces. Thus, in the smart home environment, interlocking technology between heterogeneous interfaces is essentially required for supporting communication between different networks. Further, each communication interface is a difference in power consumption, and home smart devices are often operated in 24 hours, especially smart phones and other wireless devices are sensitive to power consumption. Therefore, in order to build a energy efficient home network, It is important to select the appropriate interface to handle traffic depending on the situation. In this paper, we propose "The Heterogeneous Interface Decision Engine and Architecture for constructing of Low Power Home Network," and analyze the performance of the proposed method and verify the validity through experiments on the test bed.