• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.699-701
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• 2010

스마트폰, PDA와 같은 다양한 무선통신 단말들이 출현하면서 차량 내에서도 인터넷 서비스를 사용하려는 사용자들이 증가하고 있다. 이에 따라 이동중인 차량 내에서 인터넷 엑세스를 위해, 그리고 차량이 다른 서브넷 사이를 이동하더라도 시그널링 오버헤드가 크지 않게 하기 위해, network mobility basic support (NEMO BS) protocol이 제안되었다. 그러나 차량 내의 노드들에게 QoS를 지원하기 위해서 session admission 기법 등이 필요하다. 이 때, 차량 내에서 발생하는 세션은 new session과 handoff session으로 구분할 수 있는데, new session의 봉쇄보다 handoff session의 봉쇄가 서비스 만족도 측면에서 더 큰 임팩트를 가진다. 따라서 본 논문에서는 차량 외부에서 차량으로 이동한 노드들의 handoff session 봉쇄확률을 줄이기 위한 늦은 바인딩 업데이트 기법을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.664-667
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• 2010

VANET에서 빠른 핸드오버를 위한 Fast MIPv6를 사용하는데 있어 Mobile Node이 다음 Access Router로 이동함에 따라 새로운 주소를 생성하고 이전주소를 새로운 주소로 교환하는 과정인 Fast Binding Update가 안전하게 수행하기 위해 핸드오버 인증 프로토콜이 사용된다. 본 논문에서는 핸드오버 인증 프로토콜 중 Kempf가 제안한 SEND기반의 핸드오버 인증 프로토콜이 Sybil 공격 및 DoS 공격에 보안상 취약하므로 생기는 CPU 성능 저하 문제를 인증과정을 수행하기 전에 Access Router의 주소 리스트를 사용하여 완화시키는 방법을 제안한다. 그로 인해 CPU 성능의 효율성을 보장하도록 한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.808-811
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• 2008

HMIPv6는 핸드오버시 시그널링 오버헤드와 패킷 손실을 감소시키는데 목적이 있다. 그러나 HMIPv6는 성능 평가면에서 기존의 MIPv6보다 우수하지 못하다. HMIPv6 환경하에서 새로운 도메인에 진입한 MN이 MAP 선택시 최상위 MAP을 선택하여 CN과 통신할 경우 최상위 MAP에 부하가 집중되고 MN이 빈번하게 이동하거나 대용량서비스를 이용하게 되면 성능이 저하되고, 반대로 MN이 최하위 MAP을 선택하여 CN과 통신할 경우에는 HA나 CN에 대한 Binding Update 시그널 증가로 성능이 저하된다. 이에 본 논문에서는 MN이 MAP 선택시 Distance, 노드사용율 및 대역폭 사용율을 바탕으로 MAP을 선택하는 적응적 MAP을 선택하는 방안에 대해서 논하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.9
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• pp.39-45
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• 2009

When Mobile IPv6 is deployed in commercial network, a mobile node needs AAA services for an authentication, authorization and accounting. AAA and Mobile IPv6 are protocols which are operated independently. Then schemes which merge these protocols have been emerged. These schemes can enable a mobile node to establish a security association between the mobile node and a home agent and to perform a binding update for the home agent using AAA authentication request. But these schemes introduce many signal messages and long handover latency during the handover, since Route Optimization mode for Mobile Ipv6 is performed using Return Routability procedure. To solve this problem, we propose a scheme for Route Optimization mode that the home agent performs the binding update for a correspondent node via the AAA infrastructure between the home agent and the correspondent node instead of Return Routability procedure. For performance evaluation, we analyze signal message transmission costs and handover latencies during handover. We show performance improvement of the proposed scheme which reduces handover latency as 61% compared with the existing scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10A
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• pp.1131-1138
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• 2004

In Hierarchical Mobile Ipv6 (HMIPv6) networks, the mobility anchor point (MAP) handles binding update (BU) procedures locally to reduce signaling overhead for mobility. However, as the number of mobile nodes (MNs) handled by the MAP increases, the MAP suffers from the overhead not only to handle signaling traffic but also to Process data tunneling traffic. Therefore, it is important to control the number of MNs serviced by the MAP, in order to mitigate the burden of the MAP. We propose an adaptive load control scheme, which consists of two sub-algorithms: threshold-based admission control algorithm and session-to-mobility ratio (SMR) based replacement algorithm. When the number of MNs at a MAP reaches to the full capacity, the MAP replaces an existing MN at the MAP, whose SMR is high, with an MN that just requests binding update. The replaced MN is redirected to its home agent. We analyze the proposed load control scheme using the .Markov chain model in terms of the new MN and the ongoing MN blocking probabilities. Numerical results indicate that the above probabilities are lowered significantly compared to the threshold-based admission control alone.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11B
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• pp.960-968
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• 2006

HMIPv6 improved the handover management of basic MIPv6 by introducing the new protocol agent MAP. In this new protocol, MAP instead of the Mobile Node intercepts all packets and redirects the packets to CoA of the Mobile Node. However, this process may degrade the network performance due to the centralization phenomenon of registration occurring in the hierarchical MAP structure. ffe propose two schemes to improve real time traffic performance. First proposal is a MAP selection mettled in which MAP is selected based on traffic characteristics. And we also propose differentiated traffic processing scheme with multi-level queues when Home Agent or Correspondent Nodes process Binding Update messages. Performances of the proposed scheme are analyzed. Analysis result shows that our model has good performance in the respect of location update cost and total cost of Mobile Nodes.

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.235-242
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• 2007

Network Mobility Basic Support protocol reduces location-update signaling by making network movements transparent to the mobile nodes (MNs) behind the mobile router (MR), but causes some problems such as sub-optimal routing and multiple encapsulations. This paper proposes an Route Optimization Employing HMIP Extension for Mobile Networks (ROHMIP) scheme for nested nubile networks support which introduces HMIP concept with relation information between MNNs behind a MR and the MR in order to localize handoff, to optimize routing and especially reduce handoff signal overhead. With ROHMIP, a mobile network node (MNN) behind a MR performs route optimization with a correspondent node (CN) as the MR sends a binding update message (BU) to mobility anchor point (MAP) via root-MR on behalf of all active MNNs when the mobile network moves. This paper describes the new mechanisms and provides simulation results which indicate that our proposal reduces transmission delay, handoff latency and signaling overhead.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.6
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• pp.698-701
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• 2010

Recently, Vehicular Networks is being developed to provide variety of services such as email, ftp, and video streaming services. As IP mobility technology, Proxy Mobile IP is developed to provide these services for a VANET user. By adopting Proxy Mobile IPv6 (PMIPv6), Vehicular Networks can support IP mobility, but it may cause a proxy binding update (PBU) message when a vehicle moves from one MAG to another. In addition, if the density of vehicles on the road is high, significant PBU messages are generated. In this paper, we propose bulk PBU message to reduce signaling overhead by those PBU messages when a bunch of vehicles move from one MAG to another. When the vehicles move from one MAG to another, it generates only one bulk PBU message to update those vehicle's location. Through numerical and simulation results, we show that our proposed bulk registration reduces signaling overhead when the density of vehicles and the speed of them are high.

• Journal of KIISE:Information Networking
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• v.32 no.5
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• pp.603-614
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• 2005

The wireless LAN environment using Mobile IP is constructed and managed to be connected with Ethernet based wired networks. However, there have been many problems with wireless networks using Mobile IP. Some important facts on network performance have not been considered when introducing wireless LAN by Mobile IP to wired networks. In this paper, we suggest schemes which can solve problems on Handover latency caused by the asymmetrical connectivity of the Access Router at applying the HMIPv6 and on binding updates due to the MN frequent movement. Our proposed schemes can reduce network latency by using the HMIPv6 architecture with a virtual router layer, and reduce communication overhead by interchanging information of the MN movement between routers. Our schemes are expected to assist in constructing a more real and effective wireless LAN environment based on the HMIPv6 and FMIP.

• Journal of Information Processing Systems
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• v.5 no.3
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• pp.117-130
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• 2009

By providing ubiquitous Internet connectivity, wireless networks offer more convenient ways for users to surf the Internet. However, wireless networks encounter more technological challenges than wired networks, such as bandwidth, security problems, and handoff latency. Thus, this paper proposes new technologies to solve these problems. First, a Security Access Gateway (SAG) is proposed to solve the security issue. Originally, mobile terminals were unable to process high security calculations because of their low calculating power. SAG not only offers high calculating power to encrypt the encryption demand of SAG's domain, but also helps mobile terminals to establish a multiple safety tunnel to maintain a secure domain. Second, Robust Header Compression (RoHC) technology is adopted to increase the utilization of bandwidth. Instead of Access Point (AP), Access Gateway (AG) is used to deal with the packet header compression and de-compression from the wireless end. AG's high calculating power is able to reduce the load on AP. In the original architecture, AP has to deal with a large number of demands by header compression/de-compression from mobile terminals. Eventually, wireless networks must offer users "Mobility" and "Roaming". For wireless networks to achieve "Mobility" and "Roaming," we can use Mobile IPv6 (MIPv6) technology. Nevertheless, such technology might cause latency. Furthermore, how the security tunnel and header compression established before the handoff can be used by mobile terminals handoff will be another great challenge. Thus, this paper proposes to solve the problem by using Early Binding Updates (EBU) and Security Access Gateway (SAG) to offer a complete mechanism with low latency, low handoff mechanism calculation, and high security.