Source-Adaptation-Based Wireless Video Transport: A Cross-Layer Approach
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Source-Adaptation-Based Wireless Video Transport: A Cross-Layer Approach Qi Qu,1 Yong Pei,2 James W. Modestino,3 and Xusheng Tian3 1 Department
of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093-0407, USA of Computer Science and Engineering, Wright State University, Dayton, OH 45435, USA 3 Department of Electrical and Computer Engineering, University of Miami, Coral Gables, FL 33124, USA 2 Department
Received 25 February 2005; Revised 23 August 2005; Accepted 26 August 2005 Real-time packet video transmission over wireless networks is expected to experience bursty packet losses that can cause substantial degradation to the transmitted video quality. In wireless networks, channel state information is hard to obtain in a reliable and timely manner due to the rapid change of wireless environments. However, the source motion information is always available and can be obtained easily and accurately from video sequences. Therefore, in this paper, we propose a novel cross-layer framework that exploits only the motion information inherent in video sequences and efficiently combines a packetization scheme, a crosslayer forward error correction (FEC)-based unequal error protection (UEP) scheme, an intracoding rate selection scheme as well as a novel intraframe interleaving scheme. Our objective and subjective results demonstrate that the proposed approach is very effective in dealing with the bursty packet losses occurring on wireless networks without incurring any additional implementation complexity or delay. Thus, the simplicity of our proposed system has important implications for the implementation of a practical real-time video transmission system. Copyright © 2006 Hindawi Publishing Corporation. All rights reserved.
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INTRODUCTION
The characteristics of wireless channels provide a major challenge for reliable transport of real-time multimedia applications since the data transmitted over wireless channels are highly sensitive to the noise, interference, and the multipath environment that can cause both packet loss and bit errors. Furthermore, these errors tend to occur in bursts, which can further decrease the delivered quality of service (QoS) [1–3]. Current and future 3G systems will have to cope with this lack of QoS guarantees. As a result, the need exists for video coding and transmission schemes that not only provide efficient compression performance, but also provide relatively robust transport performance in the presence of link errors resulting in bursty packet losses. The issue of supporting error-resilient video transmission over error-prone wireless networks has received considerable attention. A number of techniques have been proposed to combat the effects of packet losses over wireless networks and thereby increase the robustness of the transmitted video [4]. In [5, 6], a “smart” inter/intramode switching scheme is proposed based on an RD analysis, but the effectiveness of this approach with bursty packet losses is not clear and it may be too complicated for im
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