• Journal of Internet Computing and Services
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• v.9 no.5
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• pp.175-183
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• 2008

Wi-Fi defines the procedure to search an AP, authenticate both station and AP, and associate the new BSS or ESS which enables the link layer handoff. One of the problems for hotspot service of Wi-Fi is "passing-object", Wi-Fi describes the messages exchanges between two neighboring APs in BSS or ESS. If the station passes through the neighboring APs before completing link-layer handoff, the path where the tunneled packets should be sent is lost. In this paper, we propose to integrate the positioning entity in a service domain to keep track the high-speed movement.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.352-355
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• 2008

네트워크 기반의 IP 이동성 지원에 대한 요구가 증대됨에 따라 IETF NetLMM(Internet Engineering Task Force Network-based Localized Mobility Management WG)에서는 Proxy MIPv6에 대한 표준화작업이 진행 중에 있다. 또한 지연시간에 민감한 실시간 서비스 (VoIP 등)를 지원하기 위해 보다 빠른 핸드오프를 위 한 다양한 기법이 제안되고 있다. 본 논문에서는 Context Transfer Protocol 개념을 적용하여 주요 지연시간이 발생되는 AAA 인증시간을 줄이고 다양한 모바일노드의 이동 시나리오를 고려하여 모바일노드의 이동성을 보장 및 지연시간을 최소화하는 기법을 제안한다.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.175-184
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• 2002

In this paper, we proposed separate queue scheme in each hierarchical cell for effective use of wireless channel. This method reduces the blocking rata of high speed mobile station's handoff in hierarchical cellular systems. Basically for the high speed mobile stations channels are allocated in macrocell and for the low speed mobile stations channels are allocated in microcell. In order to reduce the rate of forced handoff termination, some reservation channels are employed for the fast handoff calls in the macrocells. And the queue is located in each cell to be able to store handoff requests and takeback requests. The overflowed mobile station are able to perform takeback as soon as a corresponding channel is available.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.27-30
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• 2004

본 논문에서는 무선 랜 환경에서 단말을 사용하는 사용자의 이동으로 인한 서비스영역의 변화에도 끊김 없는 서비스를 제공하기 위한 방식을 제안한다 제안방식은 이동하는 단말이 사용 가능한 채널탐색과정 중 MAC주소를 참조하여 단말의 이동을 알려주는 방식을 사용한다. 기존방식과 제안방식에 대해서 시뮬레이션을 통한 성능분석을 수행하였다. 단말의 이동을 채널탐색과정에서 인식함으로 단말에게 전송되어야 하는 데이터를 버퍼링 한 후 재결합과정이 발생하면 즉시, 전송하는 방식으로 구성되므로 핸드오프 기간 동안에 Throughput 감소가 적게 이루어짐을 확인하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5B
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• pp.253-263
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• 2005

This paper proposed a mobile multicast technique to satisfy end-to-end QoS for various user requirements in mobile network environment. In order to provide seamless mobility, fast handoff technique was applied. By using L2 mobile trigger, it was possible to minimize remarkable amount of packet loss by delay occurred during handoff. To provide efficient multicast, concept of hierarchy was introduced to Xcast++, which results in a creation of HXcast++. HXcast++ optimized transfer path of multicast and reduced expensive multicast maintenance costs caused by frequent handoff. Suggestion of GMA (Group Management Agent) mechanism allows joining to group immediately without waiting IGMP Membership query during handoff. GMA mechanism will minimize the delay for group registration process and the resource usage due to delay of withdrawal process. And also use of buffering & forwarding technique minimized packet loss during generation of multicast tree. IntServ/RSVP was used to provide End-to-End QoS in local domain and DiffServ was used in global domain. To minimize reestablishment of RSVP session delay, extended HXcast++ control messages ware designed to require PATH message. HXcast++ proposed in this thesis is defined as multicast technique to provide end-to-end QoS and also to satisfy various user requirements in mobile network environment.

• 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.191-200
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• 2007

As the IEEE 802.11 WLAN has widely installed as a high-speed wireless network information infrastructure, there has been growing interest in both security and mobility of mobile terminals. However, for the case of mobile terminal employing IEEE 802.11i security standard, it is known that the user authentication procedure of IEEE 802.1x for stronger security enforcement may, due to its large delay, not be suitable for real-time multimedia communication. In this paper, we have proposed fast authentication method to resolve the above authentication delay problem, and verifies its performance via simulation analysis. Mobile terminals can get AP information reliably, and selectively execute authentication in advance during handover, which results in fast user authentication. In addition, by effectively managing the authentication information in mobile terminal, which are distributed in advance for pre-authentication, the problem of long-time revelation of authentication information has been solved.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.219-236
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• 2014

In this paper, we propose a novel Proxy Mobile IPv6 network bandwidth-efficient handoff scheme. MN are classified into slow and fast one. At first MN should be registered in the microcell for bandwidth efficient handoff scheme. microcell is overlapped to handle the overflow session request which is nested. Overflow session request in macrocell requests to go back from the boundary of the microcell to new microcell. If idle session traffic is in a cell, it is requested by the target microcell. Analysis model was developed, an existing session of the session blocking probability and forcing termination probability of the session request have improved considerably. If the total traffic load of the system is not very large, the proposed scheme has the best bandwidth efficiency and provides better quality of service (QoS) to MN without costs of a lot of processing on the system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4B
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• pp.183-190
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• 2007

The cdma2000 mobile network covers a wide area but its characteristics are high cost and low bandwidth. On the other hand, WLAN covers a small area like a hot spot area but its characteristics are large bandwidth and low cost. Thus we can provide efficient services when we employ an integration network between WLAN and cdma2000 mobile networks. In this paper, we propose an integration scheme between WLAN and cdma2000 mobile networks. In addition, we design and implement the dual mode terminal which receives seamless data services in the integrated network. The proposed dual mode terminal manages connections by monitoring the signal strength of WLAN and selecting a proper network. We validate the functions through the implementation of VOD and show the effectiveness through the performance measurement.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.103-113
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• 2008

Reducing handoff latency is essential in providing seamless multimedia service in Wireless LAN based on the IEEE 802.11 standard. Reducing authentication delay is critical in reducing handoff latency. To this end, several authentication protocols for fBst handoff have been proposed. Mishra et al. used proactive key distribution to improve the authentication delay incurred in the current standard and Park et al. proposed a new authentication protocol based on Blom's key pre-distribution scheme. In this paper, we propose an enhanced authentication protocol based on Bresson et al.'s group key protocol. If a mobile node has previously access the network, our proposed protocol only requires simple hash operations in providing mutual authentication between a mobile node and access points. Our protocol is more efficient than Park et al.'s and Mishra et al.'s technique can be used in our protocol to further enhance our protocol.