• Journal of Internet Computing and Services
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• v.6 no.3
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• pp.55-70
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• 2005

In order to provide mobile hosts with multicast service in mobile communication environment, we proposed a multicast mechanism named HXcast++ which is an extended version of the existing Xcast++ with hierarchical architecture, We assured that mobile hosts could get multicast service through an optimal path regardless of their location by making DR(Designated Router) join a group on behalf of the mobile hosts, In this present research we introduced hierarchical architecture in order to reduce the maintenance cost resulting from frequent handoff. We also proposed a GMA (Group Management Agent) based group management mechanism which enables the mobile hosts to join the group without waiting for a new IGMP Membership Query. A fast handoff method with L2 Mobile Trigger was, in this work, employed in order to reduce the amount of the packet loss which occurs as a result of the handoff, We also managed to curtail the packet loss caused by the latency of the group join by using a buffering and forward mechanism.

• Journal of Korea Multimedia Society
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• v.5 no.1
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• pp.68-76
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• 2002

Multicast in mobile host has the problem of hast mobility, multicast decision, triangle routing, tunnel convergence, implosion of retransmission, and bandwidth waste. In particular, the bandwidth waste in radio is a definite factor that decreases transmission rate. To solve the problems, this paper proposes a new multicast transmission protocol called FIM(Forward Error Correction Integrated Multicast), which supports reliable packet recovery mechanism by integrating If Mobility Support for the host mobility, IGMP(Interned Group Management Protocol) for the group management, and DVMRP(Distance Vector Multicast Routing Protocol) for the multicast routing, and it also uses FEC and the local recovery method based on receiver. The performance measurement is performed by dividing the losses into the homogeneous independent loss, the heterogeneous independent loss, and the shared source link loss model.. The result shows that the performances improves in proportion to the size of local areal group when the size of transmission group exceeds designated size. This indicates FIM is effective in the environment where there are much of data and many receivers in the mobile host.

• Journal of Communications and Networks
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• v.7 no.3
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• pp.294-306
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• 2005

Group oriented multicast applications are becoming increasingly popular in mobile ad hoc networks (MANETs). Due to dynamic topology of MANETs, stateless multicast protocols are finding increased acceptance since they do not require maintenance of state information at intermediate nodes. Recently, several multicast schemes have been proposed which scale better' with the number of multicast sessions than traditional multicast strategies. These schemes are also known as explicit multicast (Xcast; explicit list of destinations in the packet header) or small group multicast (SGM). In this paper, we propose a new scheme for small group' multicast in MANETs named extended explicit multicast (E2M), which is implemented on top of Xcast and introduces mechanisms to make it scalable with number of group members for a given multicast session. Unlike other schemes, E2M does not make any assumptions related to network topology or node location. It is based on the novel concept of dynamic selection of Xcast forwarders (XFs) between a source and its potential destinations. The XF selection is based on group membership and the processing overhead involved in supporting the Xcast protocol at a given node. If the number of members in a given session is small, E2M behaves just like the basic Xcast scheme with no intermediate XFs. As group membership increases, nodes may dynamically decide to become an XF. This scheme, which can work with few E2M aware nodes in the network, provides transparency of stateless multicast, reduces header processing overhead, minimizes Xcast control traffic, and makes Xcast scalable with the number of group members.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4411-4431
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• 2014

Mobile ad hoc networks (MANETs) have recently gained increased interest due to the widespread use of smart mobile devices. Group communication applications, serving for better cooperation between subsets of business members, become more significant in the context of MANETs. Multicast routing mechanisms are very useful communication techniques for such group-oriented applications. This paper deals with multicast routing problems in terms of stability and scalability, using the concept of stable core. We propose LMRSC (Lightweight Multicast Routing Based on Stable Core), a lightweight multicast routing technique for MANETs, in order to avoid periodic flooding of the source messages throughout the network, and to increase the duration of multicast routes. LMRSC establishes and maintains mesh architecture for each multicast group member by dividing the network into several zones, where each zone elects the most stable node as its core. Node residual energy and node velocity are used to calculate the node stability factor. The proposed algorithm is simulated by using NS-2 simulation, and is compared with other multicast routing mechanisms: ODMRP and PUMA. Packet delivery ratio, multicast route lifetime, and control packet overhead are used as performance metrics. These metrics are measured by gradual increase of the node mobility, the number of sources, the group size and the number of groups. The simulation performance results indicate that the proposed algorithm outperforms other mechanisms in terms of routes stability and network density.

• The KIPS Transactions:PartC
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• v.14C no.4
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• pp.359-364
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• 2007

Current researches on the overlay multicast mechanism in the mobile ad hoc network (MANET) maintain the network topology information of the dynamically changing MANET, which may cause severe overhead. In this paper, we propose a new overlay multicast mechanism, the region-based overlay multicast in MANET(ROME), using the geometric locations of group members. In ROME, the physical topology is divided into small regions and the scope of location updates of group members is limited to a single region. ROME provides scalability by using the coordinate of the center point of a destination region as the destination of a data packet instead of the list of member addresses of that region. Our simulation results show that ROME gives better performance in terms of the packet overhead than other schemes.

• Journal of Korea Multimedia Society
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• v.3 no.3
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• pp.280-289
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• 2000

This paper presents an efficient method to provide seamless communication in mobile wireless networks. The goal of seamless communication is to provide disruption free service to a mobile user. A disruption in service could occur due to active handoffs. There are many user applications that do not require a total guarantee for disruption free service but would also not tolerate very frequent disruptions. This paper proposes an extended staggered multicast that provides a probabilistic guarantee for disruption free service. The proposed multicast forecasts the direction and velocity for a mobile host. It is possible that data packets for a mobile host are multicasted to not all neighbor cells but a par\ulcorner of neighbor cells those the mobile host will be handoff potentially on the basis of these information. Therefore, the extended staggered multicast significantly reduces the static network bandwidth usage also provides a probabilistic guarantee for disruption free service.

• Journal of Communications and Networks
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• v.9 no.3
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• pp.296-311
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• 2007

Mobile multi-robot teams are useful in many critical applications such as search and rescue. Explicit communication among robots in such mobile multi-robot teams is useful for the coordination of such teams as well as exchanging data. Since many applications for mobile robots involve scenarios in which communication infrastructure may be damaged or unavailable, mobile robot teams frequently need to communicate with each other via ad hoc networking. In such scenarios, low-overhead and energy-efficient routing protocols for delivering messages among robots are a key requirement. Two important primitives for communication are essential for enabling a wide variety of mobile robot applications. First, unicast communication (between two robots) needs to be provided to enable coordination and data exchange. Second, in many applications, group communication is required for flexible control, organization, and management of the mobile robots. Multicast provides a bandwidth-efficient communication method between a source and a group of robots. In this paper, we first propose and evaluate two unicast routing protocols tailored for use in ad hoc networks formed by mobile multi-robot teams: Mobile robot distance vector (MRDV) and mobile robot source routing (MRSR). Both protocols exploit the unique mobility characteristics of mobile robot networks to perform efficient routing. Our simulation study show that both MRDV and MRSR incur lower overhead while operating in mobile robot networks when compared to traditional mobile ad hoc network routing protocols such as DSR and AODV. We then propose and evaluate an efficient multicast protocol mobile robot mesh multicast (MRMM) for deployment in mobile robot networks. MRMM exploits the fact that mobile robots know what velocity they are instructed to move at and for what distance in building a long lifetime sparse mesh for group communication that is more efficient. Our results show that MRMM provides an efficient group communication mechanism that can potentially be used in many mobile robot application scenarios.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.544-546
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• 2002

최근 무선 통신 기술이 빠르게 발전하면서, 모바일 사용자들의 다양한 서비스에 대한 요청이 증가하고 있다. 그리고 멀티미디어 서비스는 네트웍 효율성의 측면에서 멀티캐스트 전송 기법이 적합하다. 이에, IETF Working Group에서는 이동 컴퓨팅 환경에서 IP 멀티캐스트를 지원하기 위해 Home Subscription 과 Remote Subscription을 제안하였다[1]. 이 방법들은 각각 장.단점을 가지고 있으나, 호스트에게 연속적인 서비스를 제공하지는 못한다. 본 논문에서는 Remote Subscription에서 제공하는 최적의 경로를 사용하면서, 사용자들에게 멀티캐스트 상에서 연속적인 서비스를 제공할 수 있는 방안에 대해 제시한다. Multicast Agent는 자신이 관리하는 네트웍에 현존하는 사용자들의 멀티캐스트 그룹의 관리와 사용자들을 대신하여 그룹에 가입 및 탈퇴를 행한다. 본 논문에서 제시한 방법은 이동 가능한 지역의 Multicast Agent가 미리 멀티캐스트 그룹에 참가함으로써 기존의 제시된 연구 방법들에 비해 사용자들에게 연속적인 서비스를 제공할 수 있다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.235-236
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• 2006

IEEE 802.16 networks support mobile stations (MSs) to access broadband wireless networks while moving at a vehicular speed. However, IEEE 802.16 networks do not provide link layer native multicast capability because of point-to-multipoint connection characteristic. Due to this feature, it is not easy to adopt protocols or applications which need native link layer multicast capability. In order to solve the multicast support problem, we use the built-in LAN emulation feature of IEEE 802.16 which is based on Convergence Sublayer (CS). Our proposed operational procedures support not only the delivery of link local scope multicast packets, but also the delivery of non-link local scope multicast packets such as site local or global scope multicast packets. We also present the method of forming multicast Connection Identifier (CID) which is used to transport IP packets over IEEE 802.16 networks.

• Journal of KIISE:Information Networking
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• v.35 no.3
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• pp.227-234
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• 2008

The development of wireless network technology allows high data rate seamless communication irrespective of the place and time in various emerging mobile service environment. Unlike wired networks, however, wireless networks utilize expensive limited bandwidth. MBS(Multicast Broadcast Service), which is supported by mobile WiMAX system based on IEEE802.16e, overcomes this problem using a shared downlink channel for efficiently supporting a number of users. However. the coverage and throughput of the system are significantly affected by the channel condition. In this paper we propose on MBS system employing Mobile Multi-Hop Relay(MMR) and adaptive modulation and coding(AMC) scheme. The result of NS-2 computer simulation shows that the throughput and transmission time are substantially improved by the proposed approach compared to the existing MBS system.