• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.5
• /
• pp.1-9
• /
• 2004

In this paper, we propose a multicast routing protocol for the seamless delivery of multicast data to mobile hosts through the optimal route in IPv6-Based mobile networks. The proposed multicast routing protocol reduces the tree reconstruction overhead by limiting the tunneling length according to the mobility of mobile hosts. In this way, our protocol satisfies the bound of the end-to-end delay and supports the seamless handoff. Analytical and simulation results show that the proposed protocol has better performance in terms of the tree reconstruction, tunneling service and multicast packet loss than the previous protocols does.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.19 no.1
• /
• pp.81-92
• /
• 2009

Recently, there is a drastic increase in users interested in real-time multimedia services in the WLAN environment, as the demand of IEEE 802.11 WLAN-based services increases. However, the handoff delay based on 802.11i security policy is not acceptable for the seamless real-time multimedia services provided to MS frequently moving in the WLAN environment, and there is a possibility of DoS attacks against session key derivation process and handoff mechanism. In this paper, a secure and efficient handoff mechanism in the centralized WLAN environment is introduced to solve the security problems. The 4-way Handshake for both mutual authentication and session key derivation is replaced by the 2-way Reassociation process.

• The KIPS Transactions:PartB
• /
• v.12B no.6 s.102
• /
• pp.679-684
• /
• 2005

There are a few representative wireless network access technologies used widely. WWAN is celluar based telecommunication networks supporting high mobility, WLAN ensures high data rate within hotspot coverage, and WDMB support both data and broadcasting services correspondingly. However, these technologies include some limitations especially on the mobility, data rate, transmission direction, and so on. In order to overvome these limitations, there are various studies have been proposed in terms of 'Vortical Handoff' that offers seamless connectivity by switching active connection to the appropriate interface which installed in the mobile devices. In this paper, we propose the interface selection algorithm and network architecture to maximize the life time of entire system by minimizing the unnecessary energy consumption of another interfaces such as WLAN, WDMB that are taken in the user equipment. In addition, by using the results of analyzing multiple types of traffic and managing user buffer as a metric for vertical handoff, we show that the energy efficiency of our scheme is $75\%$ and $34\%$ than typical WLAN for WDMB and WLAN preferred schemes, correspondingly.

• The KIPS Transactions:PartC
• /
• v.14C no.6
• /
• pp.493-502
• /
• 2007

In this paper, we propose a handoff-aware DiffServ scheduler which intends to guarantee various QoS requirements of multimedia services for mobile nodes in TDD/CDMA based wireless networks. TDD is widely used duplexing mechanism in wireless communications. Unlike FDD, TDD allows a node to symmetrically communicate with a base station by using a single frequency band, resulting in high utilization of wireless resources. DiffServ is regarded as a relatively simple QoS support mechanism and thus it is easy to be extended. This is because DiffServ is not a per-flow based mechanisms and it does not require any signaling protocol. However, previously proposed DiffServ schedulers for wired networks can not be deployed directly into wireless networks since they do not consider properties of wireless networks. As a solution to the problem, DSS(DiffServ Supporting Scheduler) was proposed. DSS uses uplink channel, which is originally used for a node to require a base station to transmit packets, to support QoS efficiently. However, QoS does not consider handoff so that it can not support QoS for moving nodes from one cell to the other cell. Therefor. the proposed handoff support QoS mechanism is necessary for TCC/CDMA networks. The proposed scheme allows a mobile node to achieve seamless service without QoS degradation even for the handoff duration.

• Proceedings of the IEEK Conference
• /
• 2004.08c
• /
• pp.588-591
• /
• 2004

This paper describes a new approach to Internet host mobility. We argue that local mobility, the performance of existing mobile host protocol can be significantly improved. It proposes Fast Moving Detection scheme that based on neighbor AP channel information and moving detection table. And, it composes Local Area Clustering Path (LACP) domain that collected in AP's channel information and MN interface information. It stored the roaming table to include channel information and moving detection. Those which use the proposal scheme will need to put LACP information into the beacon or probe frame. Each AP uses scheme to inform available channel information to MN. From the simulation result, we show that the proposed scheme is advantageous over the legacy schemes in terms of the burst blocking probability and the link utilization.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.12 no.3
• /
• pp.171-177
• /
• 2012

Network mobility support has been taken into consideration for users who have multiple terminals to enjoy the seamless connectivity. This paper proposes a network mobility support scheme in the LISP architecture. During the mobile router attachment, the EID-to-RLOC mapping database is refreshed in the map server. Furthermore, map update is developed to support smooth handoff for the mobile network. An analysis of performance is given by comparing the proposed scheme with NEMO.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2001.04b
• /
• pp.639-642
• /
• 2001

차세대 이동통신망은 "ALL-IP Network" 이라고 불리는 차세대 이동 통신망을 위한 새로운 전송기술과 새로운 망으로 기존 망이 진화하게 될 것이다. 네트웍 계층에서 볼 때 기본적으로 이동단말기에서 IP 패킷을 생성하고 무선/유선 통신망을 통과할 때 이 IP 패킷이 그대로 유지되어 End-to-end 로 전달되는 것을 그 목표로 하고 있다. 본 논문에서는 두 상이한 이동 패킷 통신 시스템간의 Seamless한 통신을 위한 핸드오프를 Mobile IPv6 [4]관점에서 접근할 것이다. (Voice에 대한 고려는 생략하였다.)

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.5B
• /
• pp.253-263
• /
• 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 Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.6A
• /
• pp.791-802
• /
• 1999

This paper introduces a wireless multimedia CDMA system using a simulcasting method and configuring multiple radio links between a user and radio ports. The CDMA system with multiple links can support seamless and soft handoffs as well as port-diversity effect. We propose two transmission power control algorithms for the multiple links which support the required service quality. We perform simulations for the capacity of the proposed system. In the simulations, a system with nine ports is configured and simulated. For the uplink, as the number of the multiple links increases, the capacity also increases and immediately approaches to the theoretical upper limit. It is shown that four radio links are enough to achieve the theoretical maximum capacity. On the other hand, for the downlink, though it has the merit of soft and seamless handoff in the wireless ATM system, the capacity rather decreases as the increase of the number of the links due to the severe multiple interferences.

• Journal of Korea Multimedia Society
• /
• v.1 no.1
• /
• pp.120-129
• /
• 1998

The mobile computing is a new network environment that support s wireless network connection seamless while the portable computer is moving. This environment involves the problem of re-establishing of new network connection. The mobile computing should provide multicasting service, because multicasting is widely-used application service which delivers messages to the members of the groups. In this paper, we proposed 3-tiered mobile multicasting protocol that transfers multicast packets efficiently and reliablely. Also, we analyzed the performance of 3-tiered mobile multicasting protocol comparing with other mechanism. Our protocol is superior to other mechanism in the aspects of the handoff costs and packet delivery costs.