Interactive Video Coding and Transmission over Heterogeneous Wired-to-Wireless IP Networks Using an Edge Proxy
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Interactive Video Coding and Transmission over Heterogeneous Wired-to-Wireless IP Networks Using an Edge Proxy Yong Pei Computer Science and Engineering Department, Wright State University, Dayton, OH 45435, USA Email: [email protected]
James W. Modestino Electrical and Computer Engineering Department, University of Miami, Coral Gables, FL 33124, USA Email: [email protected] Received 26 November 2002; Revised 19 June 2003 Digital video delivered over wired-to-wireless networks is expected to suffer quality degradation from both packet loss and bit errors in the payload. In this paper, the quality degradation due to packet loss and bit errors in the payload are quantitatively evaluated and their effects are assessed. We propose the use of a concatenated forward error correction (FEC) coding scheme employing Reed-Solomon (RS) codes and rate-compatible punctured convolutional (RCPC) codes to protect the video data from packet loss and bit errors, respectively. Furthermore, the performance of a joint source-channel coding (JSCC) approach employing this concatenated FEC coding scheme for video transmission is studied. Finally, we describe an improved end-to-end architecture using an edge proxy in a mobile support station to implement differential error protection for the corresponding channel impairments expected on the two networks. Results indicate that with an appropriate JSCC approach and the use of an edge proxy, FEC-based error-control techniques together with passive error-recovery techniques can significantly improve the effective video throughput and lead to acceptable video delivery quality over time-varying heterogeneous wired-to-wireless IP networks. Keywords and phrases: video transmission, RTP/UDP/IP, RS codes, RCPC codes, JSCC, edge proxy.
1.
INTRODUCTION
With the emergence of broadband wireless networks and the increasing demand for multimedia transport over the Internet, wireless multimedia services are expected to be widely deployed in the near future. Many multimedia applications will require video transmission over links with a wireless first and/or last hop as illustrated in Figure 1. However, many existing wired and/or wireless networks cannot provide guaranteed quality of service (QoS), either because of congestion, or because temporally high bit-error rates cannot be avoided during fading periods. Channel-induced losses, including packet losses due to congestion over wired networks as well as packet losses and/or bit errors due to transmission errors on a wireless network, require customized error resilience and channel coding strategies that add redundancy to the coded video stream at the expense of reduced source coding efficiency or effective source coding rates, resulting in compromised video quality. In this paper we quantitatively investigate the effects of packet losses on reconstructed video quality caused by bit
errors anywhere in the packet in a wireless network if only error-free packets are accepted, as well as the effects of residual bit errors in the payload if errored packets are acce
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