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

A novel mobile communications system is proposed, which provides not only effective but also efficient video access for mobile users when communicating over low-bandwidth error-prone wireless links. The middleware implemented by a mobile proxy server at the mobile support station is designed for the seamless integration of mobile users with video servers, so the specific details of the underlying protocols and source/channel coding techniques are hidden to both the video server and mobile client. Based on the concept of application-level framing, the application (video codec in our case) plays a significant role in network communications that most of functionalities of the system are implemented as part of the application. As such, at the application layer, adaptive source- and channel-coding techniques are developed to jointly provide the user with the highest possible video quality. For efficient source coding, our high-performance low-complexity video-coding algorithm called a 3-D significance-linked connected component 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 mechanism is developed. Since there is no additional requirement imposed on either the mobile client or the video server, mobile users interact with the server in exactly the same way as stationary users. Extensive computer experiments demonstrate the effectiveness of the proposed system.