• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12B
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• pp.790-799
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• 2007

In this paper, we propose WLAN CR coexistence beacon protocol for thenext WLAN network. This method can provide WLAN with high-speed data rate in new WLAN architecture and network platform based on cognitive radio technology. WLAN CR devices that enter the CR network can know UHF channels by listening CR beacon including the coexistence parameter set and start using CR channel fast. During handover of WLAN device in UHF spectrums, WLAN device that lost their channel can change available channel by obtaining the current CR channel information from the CR beacon. In advance relaying coexistence parameter set to entire CR system, WLAN CR system can prepare own candidate channel set that is different with other CR system. In CR beacon and relay delay, we show the results that WLAN CR coexistence beacon protocol supports spectrum handover efficiently and decreases the probability of collision in candidate channel set.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10B
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• pp.1182-1191
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• 2011

In this paper, we propose a network-based IP mobility management scheme, called Access Independent Mobile Service with IPv4/IPv6 Dual Stack (AIMS-DS), which can provide high-quality multimedia services to IPv4/IPv6 dual-stack mobile nodes (MNs) without any interruption over various wireless/wired access networks. The proposed scheme provides an MN with a fast and reliable mobility service among heterogeneous wireless access networks through the network-based control, the complete separation method of control and data plane, the cross-layer (layer2 and layer3) interworking method for handover control acceleration, etc, In addition, the proposed AIMS-DS can provide seamless mobility service to an MN under the environments of IPv4/IPv6 coexisting networks through the home address mobility support and transport network support. Through performance evaluation with computer simulations, we have shown the superiority of the proposed AIMS-DS in terms of handover latency, packet 1085 and packet delivery latency.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.191-200
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• 2007

As the IEEE 802.11 WLAN has widely installed as a high-speed wireless network information infrastructure, there has been growing interest in both security and mobility of mobile terminals. However, for the case of mobile terminal employing IEEE 802.11i security standard, it is known that the user authentication procedure of IEEE 802.1x for stronger security enforcement may, due to its large delay, not be suitable for real-time multimedia communication. In this paper, we have proposed fast authentication method to resolve the above authentication delay problem, and verifies its performance via simulation analysis. Mobile terminals can get AP information reliably, and selectively execute authentication in advance during handover, which results in fast user authentication. In addition, by effectively managing the authentication information in mobile terminal, which are distributed in advance for pre-authentication, the problem of long-time revelation of authentication information has been solved.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.5
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• pp.209-220
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• 2013

Handover is the technology to minimize data lose of mobile devices and make continuous communication possible even if the device could be moved from one digital cell site to another one. That is, it is a function that enables the mobile user to avoid the disconnection of phone conversations when moving from a specific mobile communication area to another. Today, there are a lot of ongoing researches for fast and efficient hand-over, in order to address phone call's delay and disconnection which are believed to be the mobile network's biggest problems, and these should essentially be resolved in all mobile networks. Thanks to recent technology development in mobile network, the LTE network has been commercialized today and it has finally opened a new era that makes it possible for mobile phones to process data at high speed. In LTE network environment, however, a new authentication key must be generated for the hand-over. In this case, there can be a problem that the authentication process conducted by the hand-over incurs its authentication cost and delay time. This essay suggests an efficient key caching hand-over method which simplifies the authentication process: when UE makes hand-over from oMME to nMME, the oMME keeps the authentication key for a period of time, and if it returns to the previous MME within the key's lifetime, the saved key can be re-used.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8B
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• pp.1105-1114
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• 2010

The Proxy Mobile IPv6 (PMIPv6) has been standardized by the IETF NETLMM WG for network-based mobility management. The PMIPv6 can provide IP mobility for Mobile Nodes (MNs) with low handover latency and less wireless resource usage. But, since the PMIPv6 is basically designed for local mobility management, it cannot support directly global mobility management between different PMIPv6 domains. In the PMIPv6, since all traffic is routed through a Local Mobility Anchor (LMA), it causes a long end-to-end delay and triangular routing problem. Therefore, in this paper, we propose a fast network-based global mobility management scheme and route optimization scheme with a new network entity, called Global Mobility Agent (GMA). Numerical analysis and simulation results show that the proposed scheme is able to support global mobility between different public domains with low handover latency and low end-to-end delay, compared with the PMIPv6.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.804-810
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• 2002

The code division multiple access(CDMA) system capacity is limited by the amount of interference of the system. To reduce the unnecessary interference, this paper proposes optimized cell identification codes for site selection diversity transmission(SSDT) power control in wideband code division multiple access system of third generation partnership project(3GPP). The main objective of SSDT power control is to transmit on the downlink from the primary cell, and thus reducing the interference caused by the multiple transmission. In order to select a primary cell, each cell is assigned a temporary identification(ID) and user equipment(UE) periodically informs a primary cell ID to the connecting cells during soft handover. The non-primary cells selected by UE do not transmit the dedicated physical data channel(DPDCH) to reduce the interference. A major issue with the SSDT technology is the impact of uplink symbol errors on its performance. These errors can corrupt the primary ID code and this may lead to wrong decoding in the base station receivers. The proposed SSDT cell ID codes are designed to minimize the problem and to be easily decoded using simple fast Hadamard transformation(FHT) decoder.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.1
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• pp.38-55
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• 2013

Wireless network systems provide fast data transmission rates and various services to users of mobile devices such as smartphones and smart pads. Because many people use high-performance mobile devices, the use of real-time multimedia services is increasing rapidly. However, the preoccupation of resources by real-time traffic users is causing harm to other services-for example, frequent call interference, lowered service quality, and poor network performance. This paper suggests a resource allocation algorithm for effective traffic service support in a hybrid network. The main objective is to obtain an optimum value of data rates by comparing user requirements with the amount of resources that can be allocated. A new mechanism based on Adaptive-Quality of Service (QoS) and a monitoring system based on Queue-Aware are proposed. Adaptive-QoS supports effective resource control according to the type of traffic service, and the monitoring system based on Queue-Aware measures the amount of resources in order to calculate the maximum that can be allocated. We apply our algorithm to a test system and use Qualnet 4.5.1 to evaluate its performance.

• Journal of Internet Computing and Services
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• v.13 no.1
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• pp.15-25
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• 2012

Mobile IPv6 (MIPv6) is a host-based protocol supporting global mobility while Proxy Mobile IPv6 (PMIPv6) is a network-based protocol supporting localized mobility. This paper makes its focus on how to reduce the longer delay and extra cost arising from the combination of authentication, authorization and accounting (AAA) and PMIPv6 further. Firstly, a novel authentication scheme (Proxy-AAA) is proposed, which supports fast handover mode and forwarding mode between different local mobility anchors (LMAs). Secondly, a cost analysis model is established based on Proxy-AAA. From the theoretical analysis, it could be noted that the cost is affected by average arrival rate and residence time.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.279-282
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• 2006

최근 무선통신 서비스에서 이동성을 추가하여 이동 네트워크 서비스를 제공하기 위해 사용하는 MIPv6, FMIPv6는 긴 핸드오프 지연시간으로 인한 통신 품질의 저하 및 제어/관리 메시지로 인하여 다량의 데이터 패킷 손실, 고비용등과 같은 단점을 가지고 있다. 특히, 각 단말에서 시행하는 주소의 생성 및 유일성 검사를 위한 DAD(Duplication Address Detection)는 핸드오프 지연시간의 가장 큰 영향을 미치는 요소로서 이에 대한 연구가 요구된다. 본 논문에서는 L2(Layer 2)의 재결합 절차 상 MR(Mobile Router)/AR(Access Router)에서 직접 유일성 검사를 마친 후 생성된 주소를 재결합 응답 프레임에 추가시켜 할당하는 Cross-Layer방식을 제안한다. 또한 할당된 주소관리와 생성된 주소의 유일성 검사를 위한 캐쉬도입을 고려하여 성능평가를 하였다. 제안된 방식은 기존 알고리즘들보다 전체 핸드오프 지연시간이 $30{\sim}80%$정도의 감소효과를 보이고 있으며, 비용관점에서도 약 56%의 절감효과를 확인할 수 있었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.872-875
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• 2005

Portable Internet extended from wireless LAN has a large cell size, similar to a wireless mobile communication, and can provides the seamless service which offers middle-low speed mobility. IEEE 802.16e, the international standard of Portable Internet, uses PKMv2(Privacy Key Management) protocol for authorization and key exchange between a MSS(Mobile Subscriber Station) and a BS(Base Station). This paper first reviews and studies overall security architecture of TTA HPi standard and IEEE 802.16e which supports mobility based on WMAN(Wireless Metropolitan Area Network) standard(IEEE 802.16)