A Hybrid Error Recovery scheme for Scalable Video Transmission over 3G Cellular Broadcast Networks

The cdma2000 1xEV-DO mobile communication system provides broadcast and multicast services (BCMCS) to meet an increasing demand for multimedia data services. But the servicing of video streams over a BCMCS network faces a challenge from the unreliable and error-prone nature of the radio channel. BCMCS uses Reed-Solomon coding integrated with the MAC protocol for error recovery. We show that this is not effective for mobiles moving at the edge of service area, where the channel condition is bad, resulting in significantly lower video quality. To improve the playback quality of an MPEG-4 FGS (fine granularity scalability) video stream, we propose a hybrid error recovery scheme incorporating a packet scheduler, which uses slots saved by reducing the Reed-Solomon coding overhead. Packets to be retransmitted are prioritized by a utility function which reduces the packet error-rate in the application layer within a fixed retransmission budget by considering of the map of the error control block at each mobile node. Our error recovery scheme also uses the characteristics of MPEG-4 FGS to improve the video quality even for a slow-moving mobile which is experiencing a high error-rate in the physical channel because of error bursts. Kyungtae Kang received B.S. (1999) and M.S. (2001) degrees in computer engineering from Seoul National University, Korea. He received Ph.D. degree in Dept. of Electrical Engineering and Computer Science from Seoul National University, Korea in 2007. He is a member of IEEE and IEICE. His research interests include packet scheduling, error control, QoS provision, and energy minimization issues in nextgeneration wireless/mobile networks. In particular, he is researching the performance and energy requirements of 3G cellular broadcast services such as BCMCS and MBMS. Yongwoo Cho received the Premedical Degree from the College of Medicine, University of Ulsan, in 1997, a B.S. degree in Computer Science from Korea National Open University in 2004, while he was an military service, and an M.S. degree in Electrical Engineering and Computer Science from Seoul National University in 2006. He has worked as a researcher in Dooin Corp. and as a general manager in Bluecord Technology, Inc. His primary interests include multimedia systems, digital broadcasting, next-generation wireless/mobile networks, error control, real-time computing, and low-power design. He is currently a Ph.D. student in the School of Electrical Engineering and Computer Science at Seoul National University. Heonshik Shin received the B.S. degree in applied physics from Seoul National University, Korea, in 1973. Since he received Ph.D. degree in computer engineering from the University of Texas at Austin in 1985, he has actively involved himself in researches of various topics, ranging from real-time computing and distributed computing to mobile systems and software. He is currently a professor of School of Computer Science and Engineering at Seoul National University.