Browsing by Author "Liao, Wei-Kuo"

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An Ethernet Access Architecture for Highly Available IPTV
(2008)
Liao, Wei-Kuo
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Hsu, Ping-Hai
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Tseng, Shu-Kang
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Ling, Kang-Chiao
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電信工程研究所
We propose a practical Ethernet access architecture to support high availability and service continuity for IPTV. To reduce the per-line cost, our approach is interconnecting switches, most of which are low-cost, in a hierarchical fashion to provide broadband and cost-effective IPTV multicasting. The remaining key issue is to endow the IPTV services with high availability. To this end, we base on the redundant pair method and propose an architecture which achieves short failover process to seamlessly continue the IPTV services. In realization, our effort is restricted in extending the IGMP proxy running on the switch controller, and we describe our realization by presenting the basic design principle. To demonstrate its viability, we test our proposed architecture on ACTA which is a commercially available platform. Experiment results show that in general the failover process can be carried out within 50 ms.
Type-Aware Error Control for Robust Interactive Video Services over Time-Varying Wireless Channels
(2011-01-01)
Liao, Wei-Kuo
;
Lai, Yi-Hsuan
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電機工程學系
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Department of Electrical and Computer Engineering
We propose a scheme called Type-Aware Error Control (TAEC) to provide robust interactive video services over time-varying wireless channels. Basically, TAEC explores the temporal dependence of video frames by pushing out the lower impact frames. In doing so, queuing delay is controlled and the important frame is retransmitted multiple times. We consider the application of the nonstationary stochastic control to further improve the wireless system throughput by exploring the multiuser diversity gain. The techniques involved in our proposed solution consist of constructing a Markov model, reducing the number of parameters estimated, and avoiding the state explosion problem. The provisioning of immediate bandwidth guarantee is another feature of TAEC, i.e., when exploring the multiuser diversity gain, the users share their reserved bandwidth only if the perceived video qualities are acceptable. As shown in the simulation, TAEC improves the perceived video quality in terms of luminance PSNR when compared to other schemes.