Differentiated Protection of Video Layers to Improve Perceived Quality

Scalable video transmission over a network is easily adaptable to different types of mobile experiencing different network conditions. However the transmission of differentiated video packets in an error-prone wireless environment remains problematic. We propose and analyze a cross-layer error control scheme that exploits priority-aware block interleaving (PBI) in the MAC layer for video broadcasting in CDMA2000 systems. The PBI scheme allocates a higher priority to protecting the data which are more critical to the decoding of a video stream, and therefore has more effect on picture quality in the application layer. The use of Reed-Solomon coding in conjunction with PBI in the MAC layer can handle error bursts more effectively if its implementation takes account of underlying error distributions in the physical layer, and differentiates between different types of video packets in the application layer. We also calculate the maximum jitter from the variability of the Reed-Solomon decoding delay and determine the size of jitter buffer needed to prevent interruptions due to buffer underrun. Simulations demonstrate the extent to which we can improve the perceived quality of scalable video.