Scalable, error-resilient, and high-performance video communications in mobile wireless environments

A novel mobile communications system is proposed in the paper, which provid es not only effective but also efficient video access for mobile users when communicating over low-bandwidth error-prone wireless links, The middlewar e implemented by a mobile proxy server at the mobile support station is des igned for the seamless integration of mobile users with video servers, so t he specific details of the underlying protocols and source/channel coding t echniques are hidden to both the video server and mobile client. Based on t he concept of application-level framing, the application (video codec in ou r case) plays a significant role in network communications that most of fun ctionalities of the system are implemented as part of the application, As s uch, at the application layer, adaptive source- and channel-coding techniqu es are developed to jointly provide the user with the highest possible vide o quality, For efficient source coding, our high-performance low-complexity video-coding algorithm called a 3-D significance-linked connected componen t analysis (3D-SLCCA) is chosen, Due to its high robustness against channel -error propagation, 3D-SLCCA is well suited for wireless environments. For error-resilient channel coding, a multilayer transmission error-control mec hanism is developed, Since there is no additional requirement imposed on ei ther the mobile client or the video server, mobile users interact with the server in exactly the same way as stationary users, Extensive computer expe riments demonstrate the effectiveness of the proposed system.