• Proceedings of the Korea Society for Simulation Conference
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• 2003.06a
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• pp.61-66
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• 2003

Mobile IP has been designed only to maintain communication as they move form place to place, so it doesn't guarantee Quality of Service(QoS). QoS in mobile IP is important to provide multimedia and real-time applications services in mobile, and it is closely related to handoff delay. Therefore, handoff delay problem is actively studied to guarantee QoS as a main issue in mobile IP research area Next generation Mobile IPv6 resolve this problem somewhat, triangle problem for first packet and handoff delay still remain. In this paper, we suggest SNMP Information-based routing that adds keyword management method to Information-based routing in active network in order to resolve such a problem, and then suggest QoS controlled handoff based on SNMP Information-Based routing. After modeling of suggested method and existing handoff method simulations we carried out with NS-2 for performance evaluation. The results of simulations show the some improvement on handoff delay, and therefore on QoS improvement.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.9
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• pp.626-636
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• 2009

In Mobile IP-enabled wireless LAN (WLAN), packet flows are corrupted due to the handoff of a mobile node (MN) at the link and network layers, which results in burst packet losses and can cause temporary buffer underflow in a streaming client at the MN. This transient behavior hurts time-sensitive streaming media applications severely. Among many suggestions to address this handoff problem, few studies are concerned with empirical issues regarding the practical validation of handoff options on the time-sensitive streaming media applications. In this paper, targeting seamless streaming over Mobile IP-enabled WLAN, we introduce a seamless media streaming framework that estimates accurate pre-buffering level to compensate the handoff latency. In addition, we propose a link-layer (L2) assisted seamless media streaming system as a preliminary version of this framework. The proposed system is designed to reduce the handoff latency and to overcome the playback disruption from an implementation viewpoint. A packet buffering and forwarding mechanism with L2 trigger is implemented to reduce the handoff latency and to eliminate burst packet losses generated during the handoff. A pre-buffering adjustment is also performed to compensate the handoff latency. The experimental results show that the proposed approach eliminates packet losses during the handoff and thus verify the feasibility of seamless media streaming over Mobile IP-enabled WLAN.

• Journal of KIISE:Information Networking
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• v.29 no.5
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• pp.501-509
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• 2002

When using TCP over a mobile network, TCP responds to a handoff by invoking a congestion control algorithm, thereby resulting in a degraded end-to-end performance in a mobile network. In this paper, two schemes are proposed, TCP-MD and TCP-R. TCP-MD can detect the movement of s mobile host early on, whereas TCP-R can force the source to freeze data transmission during registration. The proposed schemes maintain end-to-end TCP semantics, making it possible to fully interoperate with the existing infrastructure. Only a small change is required in the mobile host, plus the implementation is simple because some Mobile IP messages are used to notify the handoff, eliminating the need for any additional messages. Simulations confirmed that the proposed schemes give an excellent performance under various environments.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.209-211
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• 2004

We can categorize mobility two main fields in IP environment. If Mobile IP manages macro mobility, Cellular IP deal with micro mobility. For seamless connection, it is major problem to reduce packet loss in the network layer during handoff. This paper will introduce a scheme which reduces packet loss during micro mobility which use indirect handoff mechanism in Cellular IP, and will verify the efficiency of that scheme by computer simulation.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.97-99
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• 2003

최근 무선망 수요가 급증함에 따라 무선단말기의 전원효율을 높이고 망의 오버헤드를 줄이는 한편, 단말의 위치추적을 위하여 페이징(paging) 기법이 등장하게 되었다. IP 패킷 단말의 이동성과 함께 효율적인 페이징 기법이 차세대 무선망 기술의 핵심 이슈로 떠오르고 있다. 이에 본 논문은 국내의 차세대 IP 패킷 무선망으로써 연구되고 있는 HPi(High­speed Portable internet)망을 위한 페이징 프로토콜 및 페이징 영역 구조를 제안한다.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.10
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• pp.789-797
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• 2003

An implementation scheme and some improvements are proposed to adopt public-licensed operating system, Linux and de-facto world-wide network standard, TCP/IP into the field of behavior-based autonomous mobile robots. To demonstrate the needs of scheme and the improvement, an analysis is performed on a server/client communication problem with real time Linux previously proposed, and another analysis is also performed on interactions among TCP/IP communications and the performance of Linux system using them. Implementation of behavior-based control architecture on real time Linux is proposed firstly. Revised task-scheduling schemes are proposed that can enhance the performance of server/client communication among local tasks on a Linux platform. A new method of TCP/IP packet flow handling is proposed that prioritizes TCP/IP software interrupts with aperiodic server mechanism as well. To evaluate the implementation scheme and the proposed improvements, performance enhancements are shown through some simulations.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.105-108
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• 2003

Because of increasing the notebook computer and PDA, users' requirement with respect to mobility is growing more and more. However, current IP protocol is not changed IP address and can not deliver IP packets on new location of host in case moving another network. To solve this problem, the IETF has proposed mobile IP. The network management for maintaining stable and efficient environment is more difficult according to being various by complicated network environment and requirements of provided service and user. The recent rises concern about policy-based network technology. Therefore, this paper proposed a framework of policy-based network and developed policy scenarios using the presented policy language of mobile IP.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.166-168
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• 2002

본 논문에서는 Mobile IP에서 핸드오프 중에 발생하는 패킷손실을 제거하기 위한 신뢰성 있는 핸드오프 기법을 제안하였다. 기존에 제시된 핸드오프 기법은 핸드오프 중에 발생하는 패킷손실을 줄여주지만 여러가지 문제점을 가지고 있었다. 본 논문에서는 캐쉬 에이전트(Cache Agent)가 대응 노드(Correspondent Node)를 대신하여 바인딩 캐쉬를 관리하며 대응 노드가 이동 노드(Mobile Node)에게 전송한 패킷을 버퍼링함으로써 핸드오프 중에 발생하는 패킷손실을 제거한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.489-491
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• 2009

Recently, a range of diverse networks are undergoing speedy evolution and inspiring variety applications. Among many networks, mobile Ad-Hoc networks (MANETs) are active working with a part of routing protocols. But, the majority of routing protocols have required a unique identifier, such as an IP address. At this while, IP address assignment scheme in MANET remains unsolved. When a centralized agent server is not exist, IP address is an critical issue such as a single MANET. This paper look over previous work about basic principles, also we suggest simple solution to overcome the power of two ($2^m$).

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.1433-1436
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• 2003

Mobiel IP 기반의 이동 호스트의 핸드오프시 새로운 COA를 HA에 등록하는 과정에서 많은 지연이 발생한다. 본 논문에서는 802.11 무선 LAN 환경에서 Mobile IP 기반의 이동 호스트가 핸드오프를 수행할 때 발생하는 전송 지연을 줄이기 위한 방안을 제안한다. 제안된 방식은 핸드오프 시 발생하는 전송 지연을 줄이기 위해서 802.11 MAC에서 일반적인 트래픽과 이동 호스트가 새 COA를 HA에 등록하기 위해서 발생하는 등록 요청 메세지를 분리해서 백오프를 처리한다. NS-2를 이용하여 시뮬레이션 한 결과, 일반적인 트래픽과 둥록 요청 메세지를 분리해서 백오프를 처리한 경우 Mobile IP 핸드오프 과정에서 발생하는 지연이 줄어들었음을 보였다.