• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1037-1043
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• 2006

This work presents an effective overlay multicast tree construction algorithm for synchronized real-time media multicast service over the Internet. The proposed algorithm is designed to minimize delay variance among group members to provide the synchronized service as well as average delay of group members in order to support the service in real-time. Basically, of orthogonal genetic algorithm is employed to obtain the near optimal tree with a low computational complexity since the given problem is NP-complete. Finally, experimental results are provided to show the superior performance of the proposed algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3B
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• pp.208-213
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• 2011

Since the wireless technologies based on the IP have been developed recently, a variety of mobile services has been proposed. For broadcasting services to utilize network resources efficiently, there is a need to support handover of multicast traffic in mobile networks. In this paper, we add a network function block to solve the tunnel convergence problem, and propose a new fast handover scheme to reduce handover latency for PMIPv6 networks with multicast function. With the simulation result, we show that our fast handover scheme has better performance than the draft in the IETF in the viewpoint of handover latency and multicast service disruption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.305-313
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• 2011

This paper presents a P2P (Peer-to-Peer) overlay multicast tree construction algorithm to support stable multimedia service over the Internet. While constructing a multicast tree, it takes into account not only the link delay, but also peer stability. Since peers actually show dynamic and unstable behavior over P2P-based network, it is essential to consider peer stability. Furthermore, the weighting factor between link delay and peer stability is adaptively controlled according to the characteristics of the multicast tree. Basically, Genetic algorithm is employed to obtain a near optimal solution with low computational complexity. Finally, simulation results are provided to show the performance of the proposed algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.441-450
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• 2015

Nowadays, many WLAN access points (APs) are deployed in hotspot areas such as shopping malls and stations. As the number of WLAN APs deployed increases, how to manage densely deployed APs in an efficient manner becomes one of the most important issues in WLANs. In this environment, uncoordinated multicast services can lead to frequent collisions due to simultaneous transmissions among APs. In this paper, we propose a multicast scheduling algorithm that can exploit simultaneous transmissions in multiple sectors and avoid redundant transmissions in dense networks. Simulation results demonstrate that the proposed scheme can reduce the multicast transmission latency compared to comparison scheduling schemes.

• Journal of Communications and Networks
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• v.4 no.3
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• pp.221-229
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• 2002

Adaptability is the most promising feature to be applied in future robust multimedia applications. In this paper, we propose the Direct Algorithm to improve the degree of satisfaction at heterogeneous receivers in multi-layered multicast video environments. The algorithm relies on a mechanism that dynamically controls the rates of the video layers and is based on feedback control packets sent by the receivers. The algorithm also addresses scalability issues by implementing a merging procedure at intermediate nodes in order to avoid packet implosion at the source in the case of large multicast groups. The proposed scheme is optimized to achieve high global video quality and reduced bandwidth requirements. We also propose the Direct Algorithm with a virtual number of layers. The virtual layering scheme induces intermediate nodes to keep extra states of the multicast session, which reduces the video degradation for all the receivers. The results show that the proposed scheme leads to improved global video quality at heterogeneous receivers with no cost of extra bandwidth.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.407-407
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• 2004

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.399-399
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• 2004

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.114-114
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• 2004

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.450-450
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• 2004

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.11
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• pp.2409-2424
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• 1997

Multicasting to mobile hosts(MHs) based on broadeasting results in overloaded unnecessary messages in case of th number of recipient MHs is relatively small compared with that of nodes in a network. In this paper we propose an improved multicast protocol in which messages are selectively flooded only to the (radio) cells within some distance from the cells where destination MHs reside most recently, so that the number of unnecessary messages carried in broadcasting is reduced. Detailed procedures for the protocol are provided and protocol properties are proven.