MobiStream: Error-resilient video streaming in wireless WANs using virtual channels

We present MobiStream-a video streaming system that exploits the perceptual value in the video content and the characteristics of link layer and physical layer channels to enable error-resilient video streaming over wireless wide-area networks (WWANs). The key building block in MobiStream is the use of link layer based, but application-controlled, virtual channels (ViCs) abstraction. Each virtual channel in MobiStream offers a different level of reliability and statistical loss gaurantee using 'awareness' of the link layer and physical layer channels. Video applications can dynamically instantiate new virtual channels, control their loss behavior, and/or flexibly switch video transmission across channels. MobiStream achieves fine-grained error-resilience by partitioning video frames into number of small, independently decodable, blocks of data (called 'slices') and assigns priority to each such individual slice based on its perceptual (visual) usefulness. MobiStream augments a number of other enhancements for error-resilience: multiple description video coding, perceptual slice-structured coding, low-delay inter-frame and intra-frame slice interleaving, dynamic unequal error protection, and priority-based video-data scheduling to enable efficient and error-resilient video streaming over wireless wide-area links. MobiStream has been implemented and evaluated using loss distributions from tests conducted over a commercial wide-area wireless (CDMA2000 3G) network. Results show that, MobiStream, in the face of burst packet losses can improve video picture quality by at least 4 dB. We conclude that significant benefits to end-user experience can be obtained by deploying such a video streaming system.