• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.679-681
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• 2004

무선 통신 기술의 발달로 무선 인터넷에 대한 관심과 그에 따른 이동성 지원에 대한 관심이 증가하고 있다. 또한 이동성 지원을 위한 Mobile IPv6의 Handover 시에 상대노드(CN)와의 바인딩 갱신(Binding Update) 지연시간이 문제가 되고 있다. 문제 해결을 위해서 2계층과 3계층을 연동하는 Fast Handover를 이용하여, MN에서 CN으로의 바인딩 갱신 지연시간을 단축시키고자 2계층 Handover 메시지인 IEEE 802.11의 Reassociation Request 프레임을 이용한다. MN이 Binding 갱신 메시지를 보내기 전에 CN과의 보안을 위해서 Return Routability 절차을 수행하는데 이 절차 중의 메시지인 HoTI, CoTI 메시지를 2계층 Handover 중에 미리 보냄으로써 CN과의 바인딩 갱신 지연시간을 단축시키는 방안을 제안한다.

• Journal of KIISE:Information Networking
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• v.32 no.3
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• pp.370-381
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• 2005

Mobile IP provides an efficient and scalable mechanism for host mobility within the Internet. Using Mobile If, mobile nodes may change their point of attachment to the Internet without changing their If address. However, it would result in a high signaling cost. To reduce the signaling cost, we factor in the fact that mobile users will not be actively communicating much of the time. In fact, there Is no necessity to send a binding update message to the home agent when an mobile node does not communicates with others while moving. From this point of view, we propose a lazy update strategy for minimizing signaling cost using the forwarding pointer in hierarchical Mobile IPv6. In our proposal, binding updates are sent only when a mobile node is in a busy mode. If an mobile node is in a dormant mode, binding update messages are delayed until busy mode using the forwarding pointer. As a result, our proposal can reduce the total signaling cost by eliminating unnecessary binding update messages when a mobile node Is in a dormant mode. In addition to, our proposal reduces unnecessary location update cost resulting from ping-pong effect under mobile node's dormant mode. Analysis results using the discrete analytic model presented in this paper shows that our proposal can has superior performance than hierarchical Mobile nv6 when the call-to-mobility ratio is low and the length of the forwarding pointer chain K is low.

• Journal of KIISE:Information Networking
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• v.32 no.5
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• pp.615-624
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• 2005

In Mobile IP, several types of messages - binding update, binding request and binding acknowledgement - are used to support user mobility. It is necessary to exchange those messages frequently for seamless mobility but it incurs both the increase of network overhead and poor usage of mobile node battery power Thus, we need a mechanism that the server detects users location and also copes with the problems effectively, which is our main concern in this paper Each user records all moving logs locally and periodically makes out profile based on them in HMIPv6. By using profile, estimated resident time can be computed whenever he enters an area and the time is set up as the binding update message lifetime. Of course, the more correct lifetime nay be obtained IP arrival time as well as average resident time Is considered in profile. Through extensive experiments, we measure the bandwidth usage for binding update messages by comparing the proposed schemes with that in HMIPv6. From the results, Gain gets over $80\%$ when mobile node stays more than 13 minutes in a subnet. Namely, we come to know that our schemes improve network usage and energy usage in mobile node by decreasing the number of messages while they also manage users locations like that in HMIPv6.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.261-264
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• 2004

We propose a location management with adaptive binding idle lifetime scheme for IP-based wireless network. In our proposed scheme, the binding idle lifetime value is adaptively varied according to user characteristics. The main idea is that the mobile node (MN) does location update (LU) even in idle state. Furthermore a sequential paging scheme is used to reduce the paging cost. The proposed scheme can be used in both cellular network and IP-based network.

• Journal of KIISE:Information Networking
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• v.35 no.4
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• pp.345-354
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• 2008

Recently, small-scale mobile network which is composed of many mobile devices in a man becomes popular. Also, Examples of large-scale mobile network can be thought access networks deployed on public transportation such as ships, trains and buses. To provide seamless mobility for mobile nodes in this mobile network, binding update messages must be exchanged frequently. However, it incurs network overhead increasingly and decreases energy efficiency of mobile router. If we try to reduce the number of the messages to cope with the problem, it may happen the security -related problems conversely Thus, mobile router needs a effective algorithm to update location information with low cost and to cover security problems. In this paper, mobility management scheme based on mobile router's mobility pattern is proposed. Whenever each mobile router leaves a visiting network, it records related information as moving log. And then it periodically computes mean resident time for all visited network, and saves them in the profile. If each mobile router moves into the visited network hereafter, the number of binding update messages can be reduced since current resident time may be expected based on the profile. At this time, of course, security problems can happen. The problems, however, are solved using key credit, which just sends some keys once. Through extensive experiments, bandwidth usages are measured to compare binding update messages in proposed scheme with that in existing scheme. From the results, we can reduce about 65% of mobility-management-related messages especially when mobile router stays more than 50 minutes in a network. Namely, the proposed scheme improves network usage and energy usage of mobile router by decreasing the number of messages and authorization procedure.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.4-6
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• 2005

기존 MIPv6 을 위한 바인딩 갱신(binding update) 프로토콜은 이동 노드가 새로운 외부 링크로 이동할 때마다 동일한 프로토콜을 수행하여 바인딩을 갱신한다 그러나 이동을 하지 않아도 바인딩 갱신의 수명 때문에 같은 네트워크 링크에 있더라도 바인딩 갱신을 계속 수행하여야 하므로 매번 동일한 과정을 반복하여 바인딩을 갱신하는 것은 비효율적이다 이 논문에서는 CGA(Cryptographically Generated Address) 방식의 MIPv6 을 위한 새로운 티켓 기반 바인딩 갱신 프로토콜을 제안한다. 제안한 프로토콜에서 처음으로 바인딩을 갱신할 때 대응노드는 이동 노드에게 티켓을 발급하여 준다. 이후 갱신에서는 홈 에이전트의 도움 없이 이동 노드는 대응 노드와 직접 바인딩 갱신 프로토콜을 수행할 있다. 따라서 기존 프로토콜과 달리 두 번째 갱신부터는 매우 효율적으로 바인딩을 갱신할 수 있다. 이 논문은 몇 가지 공격 시나리오를 통해 제안한 프로토콜의 안전성을 분석하며, 기존 프로토콜과 비교하여 효율성을 입증한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2009.01a
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• pp.275-278
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• 2009

MIPv6의 핸드오버 지연시간을 줄이는 많은 연구가 등장 하였고, 그 중 IEFT에서 표준화한 두 가지 프로토콜이 있다. 첫 번째 FMIPv6(Fast MIPv6) 프로토콜은 2계층 핸드오버 전에 3계층 핸드오버의 일부 과정은 사전에 수행함으로써 핸드오버 지연 시간을 줄이는 프로토콜이다. 두 번째 HMIPv6(Hierarchical MIPv6)는 일정한 범위를 커버할 수 있는 에이전트를 두어 이동성을 지역적으로 관리하여 핸드오버 지연시간을 줄이는 프로토콜이다. 본 논문에서는 FMIPv6에서 주로 사용하는 바인딩 갱신 프로토콜인 RR 프로토콜의 바인딩 갱신 절차를 줄임으로써 바인딩 갱신으로 생기는 시간을 단축시키는 방법을 제안한다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.7-8
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• 2006

F-HMIPv6 is protocol that supports fast handovers for Hierarchical Mobile IPv6. Unlike HMIPv6 (Hierarchical Mobile IPv6), it sends FBU(Fast Binding Update) by predicted Router's Information for a potential handover. But, The current version of this protocol doesn't ensure impeccably between mobile node and router. To make up for the weak points of the security, we propose the architecture for F-HMIPv6 protocol to structurally reinforce the security and improve weak security of among mobile node, MAP(Mobility Anchor Point), and routers for binding update when mobile node conducts handovers.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.448-450
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• 2003

인터넷 프로토콜의 이동성 지원(Mobile IP)은 단말의 이동성(host mobility)뿐만 아니라 네트워크의 이동성(network mobility)까지도 지원하도록 확장되고 있다. 그러나 이동 네트워크(mobile network)의 내부에 이동 단말(mobile host) 또는 이동 네트워크가 존재하는 경우와 칼이 중첩된 이동 네트워크(nested mobile network)의 경우 데이터가 전송되는 경로가 삼각형 또는 그 이상으로 복잡해지는 Triangular Routing 또는 Pinball Routing 문제가 발생하게 된다. 본 논문에서는 대응 단말(Correspondent node) 또는 Home Agent에서 위치 정보가 갱신(Binding Update)되는 과정을 재귀적으로 수행하게 함으로써 중첩된 이동 네트워크에서 최적의 경로로 데이터를 전달할 수 있도록 하는 방법을 제시한다.

• Journal of Internet Computing and Services
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• v.6 no.5
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• pp.11-25
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• 2005

In MIPv6 environment, an important design consideration for public key based binding update protocols is to minimize asymmetric cryptographic operations in mobile nodes with constraint computational power, such as PDAs and cellular phones, For that, public key based protocols such as CAM-DH. SUCV and Deng-Zhou-Bao's approach provides an optimization to offload asymmetric cryptographic operations of a mobile node to its home agent. However, such protocols have some problems in providing the optimization. Especially, CAM-DH with this optimization does not unload all asymmetric cryptographic operations from the mobile node, while resulting in the home agent's vulnerability to denial of service attacks. In this paper, we improve the drawbacks of CAM-DH. Furthermore, we adopt Aura's two hash-based CGA scheme to increase the cost of brute-force attacks searching for hash collisions in the CGA method. The comparison of our protocol with other public key based protocols shows that our protocol can minimize the MN's computation overhead, in addition to providing better manageability and stronger security than other protocols.