• Journal of the Korean Data and Information Science Society
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• v.19 no.1
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• pp.11-24
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• 2008

In this paper, the patterns of movement used in the mobile communication systems are adopted in the mobile computing environment to reduce handover delay and to support seamless handover for MIPv6 based on IEEE 802.11 networks. That is, RtSolPr message and PrRtAdv message can be treated before handover. As the result, it is possible to assign NCoA to MN and Next Access Router(NAR) before handover starts. This can minimize handover delay and reduce the total handover delay.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.1
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• pp.88-97
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• 2000

We have proposed and analysed a novel Lookup Algorithm which had a short switching speed and tiny memory size for IP router. This algorithm could simply be implemeted by a hardware with SRAM because of simple structure. This Lookup scheme needs 1${\sim}$3 memory access times. When we simulated with 40,000 routing record obtained from IPMA Website, the maximum memory size of this algorithm was 316KB(the offset threshold for compression algorithm was 8). When we simulated by HDL using ALTERA EPM7256 series and 100MHz clock and SRAM of 10ns access time, the total lookup time was 45ns for two memory access, 175ns for three memory access.

• Proceedings of the KIEE Conference
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• 2006.10b
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• pp.199-203
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• 2006

무선통신 환경에서 단말의 이동에 의해 발생되는 끊김 현상을 제거하고, 지속적인 서비스를 제공하기 위해서는 빠른 핸드오프(Handoff) 방식이 필요하다. 본 논문에서는 모든 채널을 탐색한 후, 가장 상태가 좋은 채널을 선택하는 기존 방식을 개선한다. 각 AP(Access Point)가 현재 사용하고 있는 채널정보와 ACR(Access Control Router)가 제공하는 인접 AP들 정 보의 주기적인 NEB-ADV에 포함하여 이동단말에 제공 한다. 본 논문에서는 정보를 습득한 단말이 인접한 AP들의 사용 채널만 탐색하는 새로운 Fast Channel Detection(FCD)방식을 제안한다. 제안하는 방식은 기존 방식과 비교하여 채널탐색 시간이 감소되므로 총 지연시간을 감소시킨다. 제안된 방식에 대한 시뮬레이션 모델을 통해서 링크 효율성과 블록킹 확률의 비교 분석을 통하여 제안방식의 우수성을 입증한다.

• Journal of Korea Multimedia Society
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• v.11 no.10
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• pp.1385-1391
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• 2008

The network-based IP mobility solution - Proxy MIPv6 provides a mobile node with local mobility support without requiring MIPv6 functionality of the mobile node by using two principle functional entities, LMA (Local Mobility Anchor) and MAG (Mobile Access Gateway) located in a Proxy MIPv6 domain. Yet, in case that a mobile node moves into a mobile network located in the domain, the mobile node can't receive the local mobility support any more because it can't communicate with the MAG. This paper proposes a scheme to support nested network mobility in a Proxy MIPv6 domain by adding MAG functionality to a mobile router in the mobile network and evaluates the performance of the proposed scheme. Performance analysis shows that the proposed scheme can increase the performance of handover delay, signaling costs, and packet loss ratio.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.11
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• pp.984-992
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• 2012

In this paper, we discuss a new architecture of future Internet for mobile-oriented environments, named Mobile-Oriented Future Internet (MOFI). The MOFI architecture is designed with Host Identifier and Local Locator (HILL) for identifier and locator separation. Based on the HILL separation architecture, we propose a Dynamic and Distributed Mapping System (DDMS) for identifier-locator mapping control. In DDMS, the mapping control function is distributed onto each access router in the domain, which is different from the centralized approach using a central anchor. For validation of the proposed MOFI-DDMS architecture, we implemented the data delivery and mapping control functions using Linux platform. From the testbed experimental results, we see that the DDMS architecture can give better performance than the existing Proxy Mobile IP (PMIP) protocol in terms of data transmission throughput.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.4 s.316
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• pp.79-88
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• 2007

Demand for the technology for access to device control network in industry and for access to building automation system via internet is on the increase. In such technology integration of a device control network with a data network such as internet and organizing wide-ranging DCS(distributed control system) is needed, and it can be realized in the framework of VDN(virtual device network)[1,2]. Specifications for device control network and data network are quite different because of the differences in application. So a router that translates the communication protocol between device control network and data network and efficiently transmits information to destination is needed for implementation of the VDN, This paper proposes the concept of NCS(networked control system) based on VDN(virtual device network) and suggests the routing algorithm that uses embedded system.[3]

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.12
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• pp.120-127
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• 2008

HMIPv6 draws lots of attentions in recent years for providing an efficient handover and reducing the signaling overhead. HMIPv6 employs MAP(Mobility Anchor Point) in order to minimize a signaling overhead and a local mobility management. MAP completes an efficient mobility management in HMIPv6 network environment with frequent handover. However, HMIPv6 causes load concentration at a paricular MAP and may have unnecessary latency between HN(Mobile Node) and CN(Correspondent Node) within the same network. A MAP may also disturb the route optimization in HMIPv6 network because all packets must be transmitted through a MAP. In this paper, we propose a scheme to optimize the route in HMIPv6 networks according to MAP load. We configure a threshold in order to support the better service into MAP domain. The packets do not pass through MAP and are directly transmitted to AR(Access Router) if the number of current MNs attached to the MAP exceed the desired threshold. We simulate the performance of the proposed scheme and compare with HMIPv6. Resultly, the proposed scheme reduces signaling costs and mitigates concentration of a paticular MAP as well.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5A
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• pp.509-516
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• 2008

The Fast Handover in Hierarchical Mobile IPv6(F-HMIPv6) scheme provides a seamless handover in mobile IP networks effectively. However, there is a problem that the mobile node can lose its connectivity to the previous access router because of a sudden degradation of the link quality during fast handover procedure. Additionally, in many cases, the mobile node does not have enough time to exchange messages during the fast handover procedure, especially in case of movement with high speed during handover. In this paper, we propose a modification to F-HMIPv6 that significantly reduces the time to exchange messages during fast handover procedure and thereby increases the probability which the F-HMIPv6 can perform the fast handover in predictive mode.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.727-733
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• 2008

An authentication between a user's terminal and a Access Control Router (ACR) is preceded so that a user receives secure WiBro services. Otherwise they can be exposed from many attack risks. So the Telecommunications Technology Association (TTA) constituted a mechanism of the mutual authentication for WiBro service. In mechanism a user executes the mutual authentication between a Portable Equipment (PE) and the ACR by using Portable Internet Subscriber Identity Module (PISIM). But this standard needs many message to authenticate the ACR and the users cann't use wireless Internet service. Therefore in this paper we propose the key agreement protocol between the PSS and the ACR to authenticate the PSS to ACR. At this time Power Support Device (PSD) fer supporting the calculated quantity of the PSS is participated in the key agreement protocol. The ACR sends a generated key to Key Authentication Server (KAS) via secure IPsec tunnel and then it preserves the identity of the PSS and the value of key after it enciphered them. In conclusion we analyze the security and efficiency of the proposed protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5A
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• pp.359-369
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• 2005

For large capacity optical CDMA networks, we propose a shared-type encoder/decoders based on an tunable wavelength converter(TWC) and an arrayed waveguide grating (AWG) router. The proposed encoder/decoder treats codewords of wavelength/time 2-D code simultaneously using the dynamic code allocation property of the TWC and the cyclic property of the AWG router, and multiple subscribers can share the encoder/decoder in networks. Feasibility of the structure of the proposed encoder/decoder for dynamic code allocation is tested through simulations using two wavelength/time 2-D codes, which are the generalized multi-wavelength prime code(GMWPC) and the generalized multi-wavelength Reed-Solomon code(GMWRSC). Test results show that the proposed encoder/decoder can increase the channel efficiency not only by increasing the number of simultaneous users without any multiple-access interference but by using a relatively short length CDMA codes.