Browsing by Author "Shih, Yung-Chien"

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A cross-layer signaling and middleware platform for multi-interface mobile devices
(2007)
Shih, Yung-Chien
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Hsu, Kai-Cheng
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Tseng, Chien-Chao
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資訊工程學系
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Department of Computer Science
This paper presents a middleware platform approach to provide Cross-layer Signaling and Network Event Notification mechanisms for network-aware applications. Because a mobile device may be equipped with multiple network interfaces to attach different network as it moves, a network-aware application running on the mobile device must react promptly to the changes of network environment. In order for the applications to detect network changes, the proposed middleware platform provides APIs for setting up network configuration and acquiring low-layer statuses. Therefore, an application can detect network changes promptly via Network Event Notification mechanism. We also use two network-aware applications, namely a Mobility Manager and a Modified Kphone, as examples to demonstrate the effectiveness of our middleware platform.
An end-to-end channel allocation scheme for a wireless mesh network
(2014-12-01)
Tsao, Shiao-Li
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Su, Jiun-Jang
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Huang, Kuei-Li
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Shih, Yung-Chien
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Tseng, Chien-Chao
Co-channel interference seriously influences the throughput of a wireless mesh network. This study proposes an end-to-end channel allocation scheme (EECAS) that extends the radio-frequency-slot method to minimize co-channel interference. The EECAS first separates the transmission and reception of packets into two channels. This scheme can then classify the state of each radio-frequency-slot as transmitting, receiving, interfered, free, or parity. A node that initiates a communication session with a quality of service requirement can propagate a channel allocation request along the communication path to the destination. By checking the channel state, the EECAS can determine feasible radio-frequency-slot allocations for the end-to-end path. The simulation results in this study demonstrate that the proposed approach performs well in intra-mesh and inter-mesh communications, and it outperforms previous channel allocation schemes in end-to-end throughput. Copyright (c) 2013 John Wiley & Sons, Ltd.
Fast Handoff in Secure IEEE 802.11s Mesh Networks
(2011-01-01)
Chi, Kuang-Hui
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Shih, Yung-Chien
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Liu, Ho-Han
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Wang, Jui-Tang
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Tsao, Shiao-Li (Charles)
While mesh networking is gaining momentum with widespread application, we are concerned with fast handoff in a secure mesh environment. To this end, this paper presents a means in the context of IEEE 802.11s of letting a mesh portal act as an IEEE 802.1X authenticator to reduce costly IEEE 802.1X authentication processes during handoff. Our approach is developed for alignment with IEEE 802.11s and 802.11i, keeping protocols at the station side operable with no changes. As another strength, our design applies to generic multihop wireless networks. Both analytical and simulation modeling are conducted to evaluate our scheme as well. Performance results show that our approach reduces handoff delay by up to 268% or achieves comparable performance resulting from the counterpart IEEE 802.11i scheme with high likelihood of 70%-85% successful preauthentication. Moreover, our performance analysis suggests an optimal number of access points managed by one mesh portal in a network. Qualitative and quantitative discussions indicate that our approach is applicable in pragmatic settings.