Browsing by Author "Chi, KH"

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A causal multicast protocol for mobile distributed systems
(2000-12-01)
Chi, KH
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Yen, LH
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Tseng, CC
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Huang, TL
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資訊工程學系
Causal message ordering in the context of group communication ensures that ail the message receivers observe consistent ordering of events affecting a group as a whole. This paper presents a scalable causal multicast protocol for mobile distributed computing systems. In our protocol, only a Dart of the mobility agents in the system is involved in group computations and the resulting size of control information in messages can be kept small. Our protocol can outperform qualitatively the counterparts in terms of communication overhead and hand-off complexity An analytical model is also developed to evaluate our proposal. The performance results show that the proposed protocol is promising.
A framework for mobile multicast using dynamic route reconstructions
(1999)
Chi, KH
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Tseng, CC
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Huang, TL
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交大名義發表
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資訊工程學系
A mobile computing environment allows hosts to roam while retaining access to the Internet, Multicasting is one of the most important facilities for constructing reliable distributed systems and cooperative applications. Host mobility, however, challenges multicasting in this environment: the established multicast delivery paths may frequently restructure along with host migrations, incurring expensive overheads, This paper presents a framework for network-layer multicasting while keeping a low overhead in adapting multicast routes to mobile host locations. This is achieved by partitioning the mobile environment into non-overlapping regions, so that changes in the multicast routes due to host intra-region movements are hidden from other regions, An analytical model was developed for performance evaluation. It shows that, compared with the best known proposal, our scheme reduces the average multicast latency by more than 66%, while causing less than 7% overhead.
A new locality-based IP multicasting scheme for mobile hosts
(2001-03-15)
Tseng, CC
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Chi, KH
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Huang, TL
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資訊工程學系
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Department of Computer Science
Internet protocol multicasting is a mechanism widely used in the Internet to disseminate information. Multicast delivery paths may need to be frequently restructured along with host migrations, at the expense of nontrivial overhead or multicast latency. This paper presents a scheme with short multicast latency, while retaining acceptable overhead in adapting the delivery paths to mobile host locations. We exploit the locality in host movements and keep active the networks that mobile hosts have most recently visited. As long as hosts migrate within these active networks, multicast delivery paths can remain unchanged upon host movements. Performance results show that, compared with the best known proposal, our scheme is promising. (C) 2001 Elsevier Science B.V. All rights reserved.
An approach to smooth foreign agent handoff
(2002-05-01)
Tseng, CC
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Chi, KH
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Tsai, CH
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資訊工程學系
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Department of Computer Science
For ubiquitous computing and communication, a mobile node needs to change upon movements its network- and link-layer points of attachment to the Internet. Conventionally. the network-layer protocol is unaware of the link-layer changes, so IP datagrams to and from a moving node could be lost. Considerable system performance degradation might therefore result. This paper presents a scheme to integrate the handoff procedures of the two layers in the context of Mobile IP with route optimization. Experiment results show that our scheme is promising and can reduce packet loss due to host migrations substantially.
Performance and cost analysis of mobile Internet multicast protocols
(1997)
Chi, KH
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Tseng, CC
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Chou, WK
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資訊工程學系
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Department of Computer Science
This paper presents performance analysis of two general approaches to IP multicasting in mobile environments. In the first approach, copies of each multicast datagram were forwarded to Mobility Agents in. all wireless LANs on a campus. The other approach designated the Mobility Agent as a proxy (fixed host) for its local mobile hosts to participate in communication group, thus allowing current multicast protocols on the wired backbone to be easily applied. We develop an analytical model for quantifying their performance metrics. Performance is measured in terms of the latency required for group members, fixed and mobile hosts, to receive a datagram addressed to them, network bandwidth required to accomplish a single multicast. Numerical results show that each approach can outperform the other in certain circumstances.