Adaptive UEP and Packet Size Assignment for Scalable Video Transmission over Burst-Error Channels
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Adaptive UEP and Packet Size Assignment for Scalable Video Transmission over Burst-Error Channels Chen-Wei Lee,1 Chu-Sing Yang,1 and Yih-Ching Su2 1 Department 2 Department
of Computer Science and Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan of Information Engineering, I-Shou University, Kaohsiung 840, Taiwan
Received 28 February 2005; Revised 14 August 2005; Accepted 12 September 2005 This work proposes an adaptive unequal error protection (UEP) and packet size assignment scheme for scalable video transmission over a burst-error channel. An analytic model is developed to evaluate the impact of channel bit error rate on the quality of streaming scalable video. A video transmission scheme, which combines the adaptive assignment of packet size with unequal error protection to increase the end-to-end video quality, is proposed. Several distinct scalable video transmission schemes over bursterror channel have been compared, and the simulation results reveal that the proposed transmission schemes can react to varying channel conditions with less and smoother quality degradation. Copyright © 2006 Hindawi Publishing Corporation. All rights reserved.
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INTRODUCTION
Bit errors and packet losses are common throughout the wired/wireless Internet. They severely influence the quality of delay-sensitive multimedia applications. In the current Internet architecture, the application must react to the perceived congestion in the network. The availability of simple and efficient loss models enhances the ability of applications to react. A number of studies have shown that loss patterns exhibit a finite dependence in time [1, 2]. The most generalized model of quasistationary phenomena is a finite-state Markov chain. A two-state Markov model or Gilbert model [3, 4] is often used to simulate burst loss patterns over a wired/wireless channel [5–7] because it is simple and effective. Many authors have proposed scalable video coders for Internet applications [8–11]. Of these, the fine granular scalability (FGS) [11, 12] of MPEG-4 is a highly flexible coding technique that can deliver layered video data with precise rate control. The characteristics of FGS are considered to be advantages in error-prone heterogeneous transmission environments, such as mobile video-on-demand systems. The idea of combining scalable coding with unequal error protection (UEP) has already been proven to result in transmission schemes that exhibit graceful degradation [13–18]. Several adaptive UEP assignment schemes over distinct transmission conditions have been described [13–18]; however, the inherent tradeoff between the selection of packet size and the consequent packet error rate (PER) on a multiaccess channel has not been mentioned. For wireless links, the dominant error mechanism is bit error. A larger packet corresponds to
higher probabilities of unrecoverable bit errors and packet loss. However, a smaller packet has a higher header overhead. In the context of streaming video, a lossy channel exacerbates the problem if the packet s
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