• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.69-77
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• 2006

Geocasting is a form of communication that transmits messages to all nodes within a given geographical region(i.e., the geocasting region). Most of conventional onery aware protocols were based on shortest-hop routing that is, they minimized the cost in terms of the distance and total transmission energy not considering both the residual energy at each node and the link error ratio when selecting the routes for communication. In this paper we propose a MLRG(Maximum Lifetime Reliable Geocast) protocol for energy-efficient and reliable geocasting in Ad-hoc networks. The proposed MLRG, a position-based and routing-based geocasting algorithm, maximizes the network lifetime using newly defined cost function and selecting the energy balanced routes on the basis of each node's residual energy, and provides a reliable communication considering the link error ratio.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1996.10a
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• pp.560-563
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• 1996

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.199-201
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• 2003

멀티미디어 서비스는 미디어 오브젝트의 대용량 특성으로 인해 클라이언트에게 서비스를 수행할 때 QoS를 보장하기 어렵다. 이러한 문제를 해결하기 위한 많은 연구가 진행되었는데 이중 사용자의 요구에 대한 적절한 응답시간과 서버의 부하를 줄이기 위한 목적으로 주기적인 멀티캐스트가 제안되었다. 하지만 오브젝트를 세그먼트로 나누는 이 멀티캐스트 정책은 세그먼트 개수의 증가에 따라 서버의 작업부하가 커지게 되는 단점을 가진다. 따라서 본 논문에서는 주기적인 멀티캐스트를 수행하는 서버의 작업부하를 줄이기 위해 스카이스크래퍼 멀티캐스트와 하모닉 멀티캐스트를 통해 서버의 휴지시간을 유도하고, 이에 따라 서버가 멀티캐스팅하는데 이용되는 시간을 감소시키는 멀티캐스트 정책을 제안한다.

• Journal of Korea Multimedia Society
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• v.16 no.9
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• pp.1077-1088
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• 2013

As broadcasting is the process that a node sends a packet to all nodes in the network. it is basic process used for discovering of a routes to a node and disseminating of control information message in Mobile Ad hoc NETwork (MANET). In this paper, we propose dynamically adjusted probabilistic mechanism based on distance ratio and node density for broadcasting in MANETs. The distance ratio can be calculated as the ratio of the radio strength length to the distance from sender of a node, and node density can be get from 1-hop nodes of neighbours. A mobile node receiving broadcast packets determines the probability of rebroadcasting considering distance ratio and node density of itself. Rebroadcast probability will be set as low value to a node which is located in nearby area of sender and has high 1-hop node density, So it reduces packets transmission caused by the early die-out of rebroadcast packets. Compared with the simple flooding and fixed probabilistic flooding by simulation, our approach shows better performances results. Proposed algorithm can reduce the rebroadcast packet delivery more than 30% without scanting reachability, where as it shows up to 96% reachability compared with flooding.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.3
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• pp.117-124
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• 2002

This paper proposes a fault-tolerant multicasting algorithm employing the region encoding scheme in multistage interconnection networks (MIN's) containing multiple faulty switching elements. After classifying all switching elements into two subsets with equal sizes in MIN, the proposed algorithm can tolerate the faulty pattern where every fault is contained in the same subset. In order to send a multicast message to its destinations detouring faults, the proposed algorithm uses the recursive scheme that recirculates it through MIN, We prove that this algorithm can route any multicast message in only two passes through the faulty MIN.

• The KIPS Transactions:PartC
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• v.8C no.1
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• pp.41-50
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• 2001

With growth of Internet, real time multimedia application services require guarantee of QoS (Quality of Service). However, the existing Internet based on best-effort service is not enough to support those services, so MARS model to support IP multicast over ATM networks and RSVP to provide heterogeneous QoS by resource reservation scheme are proposed. As a simulation result, it is proved that processing delay of MARS is increased and success of resource reservation is decreased as a number of QoS change request of a receiver is increased. Therefore, it is important to provide heterogeneous QoS that distribute a load of MARS caused by convergence of messages and efficiently manage the resource of network as to find out scale of receivers and frequency of QoS change request.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.159-167
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• 2005

Through the increment of group oriented application services, the multicast communication in wire/wireless network has become a widely discussed researching topic. However solution for security, efnciency and scaleability of a multicast communications are not enough to be satisfactory. Tn this paper, we Propose a new secure, efficient and scalable multicasting protocols to provide a integrated multicast service. Our protocol is an authenticated key establishment protocol which has been designed specifically for use with low powered computationally weak equipment such as Cellular phone and PDA(Personal Digital Assistant).

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.323-326
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• 2000

시간에 의존적인 대용량의 멀티미디어 데이터를 다양한 네트웍 환경에 맞도록 전송하는 방법이 다양하게 연구되고 있다. 또한 멀티미디어 데이터를 실시간으로 전송하기 위한 프로토콜로 RTP(Real-time Transport Protocol)을 적용하여 하고 있으며, 다양한 상태의 네트웍을 통한 전송에 대한 피드백(feedback) 정보인 RTCP(Real-time Transport Control Protocol) 정보를 이용하여 QoS(Quality of Service)를 관리하는 메커니즘이 연구되고 있다. 본 논문에서는 RTP/RTCP 기반의 실시간 멀티미디어 데이터 전송을 위하여 멀티캐스팅(multicasting) 환경 하에서 각기 다른 대역 폭에 대한 동적인 QoS 관리 플랫폼을 제안한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.890-899
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• 2009

One of major services for the next generation mobile satellite system will be multimedia broadcasting and multi-casting service(MBMS). An integrated satellite and terrestrial network can be considered to provide those services seamlessly and cooperatively. This paper presents efficient cooperative transmission architectures for integrated satellite and terrestrial network. First, an integrated satellite and terrestrial system architectures is introduced, and several cooperative transmission architectures for the integrated system are derived. Extensive performance simulation results reveal that the proposed architectures can improve the system performance and make an efficient transmission.

• The KIPS Transactions:PartC
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• v.10C no.5
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• pp.625-634
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• 2003

More than a decade after its initial proposal, deployment of IP Multicast has been limited due to the problem of traffic control in multicast routing, multicast address allocation in global internet, reliable multicast transport techniques etc. Lately, according to increase of multicast application service such as internet broadcast, real time security information service etc., overlay multicast is developed as a new internet multicast technology. In this paper, we describe an overlay multicast protocol and propose fast join mechanism that considers switching of the tree. To find a potential parent, an existing search algorithm descends the tree from the root by one level at a time, and it causes long joining latency. Also, it is try to select the nearest node as a potential parent. However, it can't select the nearest node by the degree limit of the node. As a result, the generated tree has low efficiency. To reduce long joining latency and improve the efficiency of the tree, we propose searching two levels of the tree at a time. This method forwards joining request message to own children node. So, at ordinary times, there is no overhead to keep the tree. But the joining request came, the increasing number of searching messages will reduce a long joining latency. Also searching more nodes will be helpful to construct more efficient trees. In order to evaluate the performance of our fast join mechanism, we measure the metrics such as the search latency and the number of searched node and the number of switching by the number of members and degree limit. The simulation results show that the performance of our mechanism is superior to that of the existing mechanism.