• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.257-266
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• 2002

In 3GPP2 wireless data communications, Mobile IP is used to support macro mobility and PDSN performs the function of foreign agent. The mobility supported when a mobile station moves from one PDSN to another is called a macro mobility. In this Paper, we first examine the possibilities of packet loss and change of packet sequences that can be occurred in macro mobility. Then, to resolve such Problems, we suggest a seamless handoff algorithm in PDSNs based on packet sequence control for each of down-stream and up-stream cases respectively.

• 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.

• The KIPS Transactions:PartC
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• v.9C no.1
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• pp.97-106
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• 2002

In 3GPP2 standard, MIP is used and a PDSN performs the function of FA to support macro mobility. When a MS is roaming from a PDSN area to another, the mobility supported is called macro mobility, while it is called micro mobility when a MS is roaming from a RN area to another in a PDSN area. Since a PDSN performs the function of FA in 3GPP2 standard, it is possible to support mobility but its mechanism is actually for supporting macro mobility, not for micro mobility, thus it is weak in processing fast and seamless handoff to support micro mobility. In this paper, we suggest the seamless handoff algorithm barred on multicast group mechanism to support micro mobility. Depending on the moving direction and velocity of a MS, the suggested algorithm constructs a multicast group of RNs on the forecasted MS's moving path, and maximally delays RNs'joining to a multicast group to increase the network efficiency. Moreover, to resolve the buffer overhead problem of the existent multicast scheme, the algorithm suggests that each RN buffers data only after the forecasted handoff time. To prove deadlock freeness and liveness of the algorithm. we use state transition diagrams, a Petri-net modeling and its reachability tree. Then, we evaluate the performance by simulation.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.1125-1128
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• 2003

Increased use of PDA and Laptop has accelerated the development of wireless networking. With the tendency the need to support efficient and seamless data transmission technique has also been increased. However current mobility management protocol, such as the Mobile If, which is defined in RFC 2002, does not cover well these requirements. To satisfy these requirements, we should reduce Handoff processing time occurred by the movement of MN (Mobile Node) about the other networks. This paper proposes efficient Handoff mechanism on the new Mobile IP architecture using the Extended Macro that is a group organized with subnetworks, and sewed by a new added agent.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.2
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• pp.394-408
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• 1996

In this paper, we classify the transfer method of overflowed traffic from microcell to macrocell in micor/macro overlaid PCS system using CDMA technology, and analyze the traffic characteristics of traffic transfer methods. Soft-handoff is charaterized by communications with a new bastation on the same CDMA frequency assignment before terminating communications with the old basestation. Therefore, soft-handoff is superior to hard-handoff with respect to Grade Of Service, but it decreases the carried traffic of system. Therefore, we analyze the effect of soft-handoff with respect to handoff area variation. In order to analyze soft-handoff effect, we resolve the probability of dewelling time in soft-handoff area, and calculates the carried traffic of microcell using this result.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3A
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• pp.195-202
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• 2005

The third generation cellular system requires the seamless macro/micro mobility support. Mobile IP provides a simple and scalable macro mobility solution but lacks the support for fast handoff control in micro-domain. However, A lot of micro-mobility protocols have been proposed to complement the Mobile IP capability by providing the fast, seamless, and local handoff control. Cellular If also provides the seamless mobility support in limited geographical area. But semi-soft handoff mechanism of Cellular IP produces the packet loss and the duplication problem due to the difference of propagation delay between the new path and the old path. In this paper, we present an efficient handoff mechanism in micro-domain. The proposed handoff mechanism uses the SCD (Suitable Cross Delay) in order to minimize the packet loss and the duplication problem during the handoff. Also, the proposed mechanism is verified by the performance evaluation through the NS-2 Simulation.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.323-326
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• 2007

Mobility Anchor Points are used for the mobility management in HMIPv6 networks. Currently a mobile node selects the MAP farthest away from itself as a new MAP among available candidates when it undertakes a macro handoff. With this technique, however, the traffic tends to be concentrated at a MAP with the largest domain size and the communication cost increases due to the distance between the mobile node and the MAP. In this work, we proposed a cost effective MAP selection scheme. When leaving the current MAP domain. the mobile node calculates the optimum MAP domain size to minimize the local mobility cost at the new MAP domain considering mobile node's velocity and packet transmission rate. The mobile node then selects a MAP domain of size close to the optimum domain size calculated among the candidate MAP domains. In this way, it is possible for the mobile node to select an optimal MAP adaptively taking the network and node states into account, thus reducing the communication cost.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04b
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• pp.1141-1144
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• 2001

3GPP2 방식의 무선 데이터 통신에서는 Macro Mobility 지원을 위하여 Mobile IP가 이용되며 PDSN은 Foreign Agent의 기능을 수행한다. 이때 하나의 PDSM에서 다른 PDSN으로 Mobile Station이 이동할 경우 지원되는 이동성을 Macro Mobility라 한다. 본 논문은 Macro Mobility에서 발생할 수 있는 패킷의 손실 및 오류에 대한 가능성을 살펴보고, 이러한 문제점을 보완하기 위한 방법으로 패킷의 Down Stream과 Up Stream의 각 경우에 대하여 Packet Sequence Control을 적용한 PDSN간의 Seamless 핸드오프 알고리즘을 제시한다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.182-185
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• 1998

In the two-tier CDMA cellular system with microcells and overlaying macrocells, slow-moving mobile user are assigned to microcells and those who move fast are assigned to overlaying macrocells in order to minimize the total number of handoffs. With this consideration the problem is how to find the thresholds by which the system distinguishes fast-moving user from those who move slowly based on the estimated speed of users. In this paper, two methods for the mobile speed estimation are proposed and two operations schemes for micro-macro cellular CDMA system are suggested. Based on these, Optimization models to find the optimal thresholds for micro-macrocell selection, which are subject to the constrains of QoS, are developed in view of minimizing the weighted total number of handoffs. And then algorithms to find optimal solutions of the models are devised.

• Journal of Industrial Technology
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• v.26 no.B
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• pp.207-213
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• 2006

Mobility Anchor points are used for the mobility management in HMIPv6 networks. Currently a mobile node selects the MAP farthest away from itself as a new MAP among available candidates when it undertakes a macro hand off. With this technique, however, the traffic tends to be concentrated at a MAP with the largest domain size and the communication cost increases due to the distance between the mobile node and the MAP. In this work, we propose a novel scheme to select a MAP to minimize the communication cost, taking the mobile node's moving speed and data rate into account. To come up with the scheme we analyses the communication analyses the communication cost into the binding update cost and the data packet delivery cost, and derive an equation representing the optimal MAP domain size to minimize the total cost.